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Unveiling Non-isothermal Crystallization of CaO–Al2O3–B2O3–Na2O–Li2O–SiO2 Glass via In Situ X-ray Scattering and Raman Spectroscopy

  • Shubo Wang
    Shubo Wang
    Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland
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  • , 
  • Ekta Rani
    Ekta Rani
    Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland
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  • , 
  • Francis Gyakwaa
    Francis Gyakwaa
    Process Metallurgy Research Unit, University of Oulu, Oulu FI-90014, Finland
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  • , 
  • Harishchandra Singh*
    Harishchandra Singh
    Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland
    *Email: [email protected]
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    Orcidhttps://orcid.org/0000-0001-7754-5648
  • , 
  • Graham King
    Graham King
    Canadian Light Source, 44 Innovation Blvd., Saskatoon, Saskatchewan S7N 2V3, Canada
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    Orcidhttps://orcid.org/0000-0003-1886-7254
  • , 
  • Qifeng Shu*
    Qifeng Shu
    Process Metallurgy Research Unit, University of Oulu, Oulu FI-90014, Finland
    *Email: [email protected]
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  • , 
  • Wei Cao
    Wei Cao
    Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland
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    Orcidhttps://orcid.org/0000-0003-3139-1780
  • , 
  • Marko Huttula
    Marko Huttula
    Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland
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  • , and 
  • Timo Fabritius
    Timo Fabritius
    Process Metallurgy Research Unit, University of Oulu, Oulu FI-90014, Finland
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Cite this: Inorg. Chem. 2022, 61, 18, 7017–7025
Publication Date (Web):April 25, 2022
https://doi.org/10.1021/acs.inorgchem.2c00387

Copyright © 2022 The Authors. Published by American Chemical Society. This publication is licensed under

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Abstract

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The crystallization in glasses is a paradoxical phenomenon and scarcely investigated. This work explores the non-isothermal crystallization of a multicomponent alumino-borosilicate glass via in situ high-energy synchrotron X-ray diffraction, atomic pair distribution function, and Raman spectroscopy. Results depict the crystallization sequence as Ca3Al2O6 and CaSiO4 followed by LiAlO2 with the final compound formation of Ca3B2O6. These precipitations occur in a narrow temperature range and overlap, resulting in a single exothermic peak in the differential scanning calorimetry thermogram. The concurrent nucleation of Ca3Al2O6 and CaSiO4 is intermediated by their corresponding hydrates, which have dominantly short-range order. Moreover, the crystallization of LiAlO2 and Ca3B2O6 is strongly linked with the changes of structural units during the incubation stage in non-isothermal heating. These findings clarify the crystallization of multicomponent glass, which have been inferred from ex situ reports but never evidenced via in situ studies.

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Synopsis

This work explores the non-isothermal crystallization behaviors of multicomponent alumino-borosilicate glasses via in situ high-energy synchrotron X-ray diffraction, atomic pair distribution function, and Raman spectroscopy.

Introduction

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The subject of controlled crystallization within a glass matrix has received intense attention in the glass-crystalline and crystalline materials’ production field due to the feasibility of regulating the glasses’ properties. (1,2) In the steel industry, glassy materials are employed as mold fluxes to improve the efficiency and smoothness of continuous steel casting and the surface quality of the steel products. (3−5) Crystallization of such mold fluxes contributes to different heat transfer behaviors between crystalline and glassy mold fluxes. (3) This reduces the heat transfer between the mold and crystalline layer of mold fluxes, leading to mild cooling of the solidified shell and suppressing uneven solidification in the mold. (6)
The mold flux glasses for casting carbon steels are mainly based on a CaO–SiO2–CaF2 system (7−10) wherein CaF2 controls the viscosity, crystallization, and melting temperature of the fluxes during continuous casting. (11) However, volatile and soluble fluorine (F) results in the corrosion of casting facilities and environmental pollution. (4) The F-free mold flux can be achieved by alterative components involved, such as B2O3, Li2O, and Na2O. (12,13) Additionally, during casting of the new third-generation advanced high-strength steels, (14) their relatively high Al content leads to a gradual increase in Al2O3 but a decrease in SiO2 in the CaO–SiO2-based flux owing to the strong reaction (4[Al] + 3SiO2 = 2Al2O3 + 3[Si]) at the steel melts/fluxes interfaces. (15,16) These dynamic compositional changes in fluxes would cause reduced lubrication, non-uniform heat transfer, and consequently poor casting efficiency. New mold fluxes based on alumino-borosilicate (CaO–Al2O3–B2O3) glasses have been proposed to suppress the oxidation–reduction reaction between SiO2 in mold flux and [Al] in steel melts at casting temperatures. (17)
In contrast to the well-documented crystallization characteristics of conventional silicate glasses, (18−20) crystallization kinetics of alumino-borosilicate glasses is not well understood. Meanwhile, most of the research on the crystallization of glasses mainly focuses on stoichiometry glasses with only a few components, (21) whereas mold flux glasses contain more than five components to tune the properties and behaviors (viscosity, melting, and crystallization). (8,22,23) For example, alkali, mainly Li and Na oxides added into the glasses, provides free oxygen in the glass network and decreases the viscosity. The tendency of crystallization of such glassy fluxes is high, and the crystalline products usually have variations in compositions compared with the glass matrix. These emerging factors require profound knowledge about crystallization mechanisms and kinetics for controlling crystallization and achieving a comprehensive application of the mold fluxes in the steel industry.
In this work, the crystallization of a complex alumino-borosilicate glassy mold flux has been probed via combinative high-energy synchrotron X-ray diffraction (HE-SXRD), atomic pair distribution function (PDF), and Raman spectroscopy in the in situ modes. Temperature-dependent material variations in the glassy matrix are estimated by differential scanning calorimeter (DSC) thermograms, a commonly used method to reveal the boundary between supercooled liquid and solid (Tg, glass transition temperature) and crystallization and melting characteristic temperatures. The crystallization of phases and the corresponding structural arrangement in short- and medium-range orders are determined by HE-SXRD and PDF, respectively. Information and correlations about the chemical structure are also provided and established by Raman spectrometry. This in situ study explores the crystallization mechanism during the non-isothermal annealing process.

Experimental Section

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Material Synthesis

The investigated glass composition, shown in Table 1, was chosen from a previous work. (24) The raw materials used to fabricate this glass were analytic-grade CaCO3 (>99%), α-Al2O3 (>99%), H3BO3 (>99.95%), Na2CO3 (>99.9%), Li2CO3 (>99.9%), and SiO2 (>99%) supplied by Sinopharm Group Co. Ltd. After removing moisture and thorough mixing, mixtures of raw materials were transferred to a Pt crucible and melted at 1723 K for 2 h. The melts were quenched into the water to obtain the glassy sample. The sample was stored in an ambient environment to follow the application conditions.
Table 1. Composition of the Investigated Glass
 CaOAl2O3B2O3Na2OLi2OSiO2
wt %37.034.08.08.08.05.0
atom %26.433.311.57.716.15.0

DSC Measurements

To determine crystallization behaviors, the transformation temperatures were first determined by DSC measurements using a thermal analyzer (STA 449 F3, Netzsch-Gerätebau Gmbh) with Ar gas as the purge gas. Temperature and sensitivity calibration was performed before DSC measurements using high-purity metals with known melting points as reference materials. DSC signals were obtained by heating the glass powder samples to 1400 °C at a heating rate of 20 °C/min. Pt crucibles with a Pt lid were employed to minimize the loss of volatile materials, and high-purity alumina powder was used as the inert reference material.

In Situ HE-SXRD and PDF

The in situ HE-SXRD and in situ PDF of the powder glass were carried out at the Brockhouse High Energy Wiggler Beamline, (25) Canadian Light Source, Canada. The refined wavelength of the monochromatic focused beam from standard Ni calibrants was 0.1771 Å. A 2D Perkin Elmer area detector (200 × 200 μm2 pixel size, 40 × 40 cm2 in area) placed behind the sample allowed XRD and PDF data acquisition in transmission mode. The detector to sample distance was found to be 1230 mm for HE-SXRD and 160 mm for PDF, which allowed a Qmax of 17 Å–1. An exposure time of 2.0 s was used, and the X-ray beam size was approximately 100 μm vertical and 200 μm horizontal. The powder glass sample, at ambient atmosphere, was heated using a flow-cell furnace. (26) In this case, the powder glass sample was quickly heated from room temperature (RT) to 800 °C with a ramp rate of 20 °C/s in a stepwise manner, as shown in Figure 1. During the heating process, the fast ramp rate was employed to minimize the additional nucleation or crystal growth. At each temperature, the sample was stabilized for 3 min for data acquisition. The data were processed using GSAS-II software. (27)

Figure 1

Figure 1. Schematic temperature regime for in situ measurements. The circles highlight the temperatures where the HE-SXRD patterns were collected, while the cubes represent the temperatures where both the HE-SXRD and PDF spectra were collected.

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The percent crystallinity is determined by the ratio of the integrated intensity of the diffraction pattern from the crystalline peaks to the total scattered intensity after subtracting the background scattering (28)
(1)
where xc is the percent crystallinity (wt %), Icrystal is the integrated intensity of all crystalline peaks, and Iglass is the integrated intensity of the amorphous glass scattering. The weigh fraction of the crystalline phase is calculated using (29)
(2)
where wk is the weight percentage of the kth component, Ijk is the integrated intensity of the jth diffraction line of the kth component, Nk is the number of observed diffraction lines in the defined 2θ range, ni is the number of electrons belonging to the ith atom in the chemical formula unit, Mk is the chemical formula weight, and Gjk is given by Gjk = 2 sin θjk sin 2θjk/(1 + cos2 2θjk).

In Situ Raman Spectroscopy

The structural analysis by PDF can be qualitative, and a more definitive analysis method can supplement the obtained results. Using the in situ Raman measurement, the change in the degree of polymerization based on the alumino-borosilicate glassy mold flux network was further assessed. A confocal micro-Raman spectrometer, with an excitation wavelength of 532 nm, from B&W Tek with a rotatable stage was used for this study. The in situ Raman spectra were collected at RT and elevated temperatures (same as the one used for PDF) in the spectral range of 100–2000 cm–1. Spectral deconvolution was done using Peakfit software, employing a minimum number of bands to achieve optimum peak fitting. A Gaussian line shape was used to fit the peaks associated with the different structural units; the intensities and widths were unconstrained and independent.

Results

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DSC

The DSC traces with the thermogravimetric (TG) curve from the as-prepared powder glass, shown in Figure 2, can be divided into three different sections: the glass zone (room temperature to 505 °C), crystallization zone (∼505–820 °C), and melting zone (>820 °C). The powder remains in a glassy state until ∼505 °C. At the low-temperature glass zone, fluctuations of the DSC traces are mainly associated with the relaxation below the glass-transition temperature and dehydration of the as-quenched glass. (30,31) Afterward, the endothermic glass-transition reaction in the DSC curve is due to a change in the heat capacity attributed to the transformation of glass structures, (2) and the corresponding glass-transition temperature is located at around Tg = 505 °C. Followed by, a robust exothermic peak at Tp1 = 558 °C (peak crystallization temperature) is seen, corresponding to the formation of crystalline phases. The onset of the crystallization temperature is estimated as Tc = 542 °C. It should be noted that there is also a shoulder exothermic peak at Tp2 = 604 °C, indicating minor crystallization events. A weak but long tail follows this crystallization peaks until melting. The small exothermic peak, prior to the melting peaks is most probably connected with a small fraction of less perfect crystals formed after crystallization. These events, seen in multicomponent glasses, (32) indicate incomplete crystallization before melting. This powder flux exhibits multiple melting peaks with the deepest at ∼1062 °C, showing a multi-stage melting behavior that is frequently observed in glass materials with multiple components. (33,34) As the investigations in this work were focused on the crystallization process, the temperature range for in situ studies was set from RT to 800 °C.

Figure 2

Figure 2. DSC and TG curves of the investigated mold flux glass powder (heating rate: 20 °C/min).

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In Situ HE-SXRD

Figures 3 and 4 show the 1D integrated HE-SXRD profiles acquired on the sample and determined phase fractions at different temperatures during the in situ heating experiment. At RT, the diffraction pattern consists of a broad hump from 2.8 to 4.2° from the glassy matrix. It should be noted that some sharper but still hump-like diffraction peaks also show up, which can be indexed to cubic calcium aluminate hydrate Ca3Al2O6·6H2O (ICDD PDF 00-024-0217) and monoclinic calcium silicate hydrate 5CaO–2SiO2–H2O or 2Ca2SiO4·CaO·H2O (PDF 04-012-5147), which are commonly seen and developed rapidly in cement. (35−37) In this case, the water sources might be (i) free water standing at the powder flux surfaces and pores due to the long-time storage in the ambient atmosphere, (ii) water absorption in pores, and (iii) Si–OH and Al–OH chemically bounded groups. (38) It must be pointed out that these hydrate phases are much closer to glass than that to the crystal, as shown in the PDF curve at RT in which short-range (<5 Å) order, less medium-range order, and long-range (>10 Å) disorder are seen (Figure 5). The formation of such disordered species may be due to the clustering of Al/Si and Ca in the glass matrix. (39)

Figure 3

Figure 3. (a) Integrated 1D HE-SXRD profiles acquired during the in situ heating experiment at different temperatures; (b) magnified view of the 1D HE-SXRD profiles, in which the dash lines highlight the positions of the most substantial diffraction peak of crystalline phases. The patterns were indexed by referring to the ICDD PDF4+ database. (40)

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Figure 4

Figure 4. Weight fraction of phases as a function of temperature, estimated by quantitative analysis of HE-SXRD patterns.

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Figure 5

Figure 5. In situ PDF data for a sample showing possible distributions of all atom–atom distances at selected temperatures. (a) r range from 1 to 20 Å and (b) r range from 1 to 5 Å.

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Dehydration of free-standing and absorbed water occurs at relatively low temperatures, while a higher temperature is required to break the bonding of Si–OH and Al–OH. (38) No significant change has been observed when heating to 200 °C. The hydrates start to dehydrate in the temperature range from 200 to 400 °C as the peaks from crystalline cubic Ca3Al2O6 (PDF 00-008-0006) and monoclinic Ca2SiO4 (PDF 01-080-8935) are visible at 400 °C. There is also the emergence of a weak peak corresponding to a tetragonal LiAlO2 (PDF 01-085-3652). When the temperature reaches 500 °C, signals from hydrate phases disappear entirely, and a clear crystalline LiAlO2 shows up. Here, the crystallization onset temperature is different from the one determined by DSC, which could be attributed to the different applied heating rates and the holding time at specific temperatures for data acquisition. At 550 °C, peaks corresponding to trigonal Ca3B2O6 (PDF 00-026-0347) turn up. Afterward, the relative intensity of crystalline peaks increases gradually with the increasing temperature, while the broad hump due to the amorphous glassy matrix tends to disappear simultaneously, implying that the degree of crystallinity increases in Figure 4. Quantification of the fractions of crystalline phases shows that both Ca2SiO4 and Ca3Al2O6 increase sharply at 400–500 °C, after which the Ca3Al2O6 fraction levels off until 700 °C followed by an increase at 800 °C. While the fraction of Ca2SiO4 increases gradually until 650 °C and then levels off. A gradual increment of LiAlO2 and Ca3B2O6 is observed after 400 and 500 °C, respectively. After cooling down to RT, only right shifts of peaks are detected due to the thermal contraction of the crystalline lattices.

In Situ PDF

The PDF of the powder flux at representative temperatures is plotted in Figure 5. The PDF, G(r), depicts the distributions of all atom–atom distances in the sample and can provide information on the in situ changes in the local structures of an amorphous/crystalline material. (23) As seen in Figure 5a, short-range order up to <5 Å and long-range disorder >10 Å are clear for the flux up to 400 °C. Weak structural correlations are seen in the medium range (5–10 Å). The PDF data do not allow conclusions associated with the disposition of water or Al(Si)–OH hydroxyl groups as the water content present may be too small to detect using the PDF method. (41) Nevertheless, the atomic order at the medium-length scale of crystalline hydrate phases in the HE-SXRD pattern is amorphous.
With increasing temperatures, an apparent increment of medium- and long-range order is visible along with increasing temperatures, as shown by the well-defined peaks in G(r) beyond r = 5 Å. The most intense feature in all PDFs in Figure 5b is a sharp peak at 1.74 Å, which is attributed to the Al–O and Si–O bonds that have similar bond distances. Bond valence considerations indicate that the average bond length for Al with coordination numbers of 4, 5, and 6 should be 1.76, 1.84, and 1.91 Å, respectively, suggesting that Al is tetrahedral primarily in the sample at all temperatures. The Si–O bond length for Si in [SiO4]4– tetrahedral coordination should be around 1.61 Å. (42) It is difficult to distinguish the Al–O and Si–O bonds in this study because this requires data collection at cryogenic temperatures, high resolution, and careful peak deconvolution; (42) however, the PDF data here is collected at room and elevated temperatures. Hence, this significant Al(Si)–O peak at all temperatures is attributed to the higher density of tetrahedrally coordinated Al(Si)–O bonds due to the formation and stabilization of crystalline Ca3Al2O6, LiAlO2, and Ca2SiO4.
The next intense peak at ∼2.37 Å can be attributed primarily to Ca–O bond lengths, although the nearest neighbor B–Al and B–B distances may also contribute to a much smaller extent. The intensity of this peak decreases gradually with the increase in temperature from RT to 800 °C. At RTc, after cooling down, the intensity of this peak decreases sharply, and another peak at ∼2.63 Å appears. In Ca3Al2O6, whose formation is evident from the in situ HE-SXRD, the tetrahedral [AlO4] rings are connected by Ca2+ ions. As per the literature, (43) six different Ca sites exist. Three of them, Ca(1–3), form subcell (A), and Ca(4–6) form subcell (B). All calcium atoms in the framework (A) are coordinated to six oxygen atoms with the average Ca–O bond lengths of 2.33, 2.39, and 2.35 Å for Ca(1), Ca(2), and Ca(3), respectively. Calcium atoms forming the framework (B) occupy somewhat irregular environments, and the average Ca–O distances in framework (B) are longer than for framework (A). Ca(4) atoms coordinated by nine oxygen atoms have an average Ca–O distance equal to 2.69 Å, while Ca(5) atoms coordinated by eight have an average Ca–O distance of 2.62 Å, and Ca(6) atoms are coordinated by seven oxygen atoms with an average Ca–O distance of 2.52 Å. A close resemblance of the observed bond distance of 2.63 Å with the literature indicates that the Ca atom is dominantly coordinated by eight O atoms in the studied flux sample after crystallization. The increase in width of these intense peaks indicates a broader distribution of Al–O and Ca–O bond lengths, suggesting that the polyhedra become less regular with the increase in the temperature. This trend can be linked to the increase in polymerization. An AlO4/Ca–Ox with several terminal O atoms can quickly form a nearly ideal polyhedron; however, as it becomes connected to more other polyhedra, the tetrahedron will need to distort to connect to them all.
A weak peak observed at about r = 1.2 Å can probably be assignable to the B–O and possible O–H correlations. In boron glasses with high CaO content, B atoms tend to present in [BO3]3– trigonal coordination forming boron-oxygen triangles. (44) The value of r is 1.369 Å for B–O bonds in the literature. (45) Thus, interpreting this peak is very tricky and challenging due to the low contribution of B–O bonds to the PDF, potential overlap with low-r termination noise, and with possible O–H bonds.

Raman Spectroscopy

The Raman spectra of the mold flux glass are shown in Figure 6. The Raman spectra consist of dominant vibration bands in three different frequency regions, i.e., a low-frequency region between 450 and 550 cm–1, the medium region between 750 and 850 cm–1, and the high-frequency region of 850–1000 cm–1. At RT, the complex broad bands between 450 and 900 cm–1 are developed by ring breathing vibrations characteristic of the initial glassy network. As the crystallization progress proceeds revealed by the DSC thermogram, these complex broad bands turn into more well-defined peaks at elevated temperatures.

Figure 6

Figure 6. In situ high-temperature Raman spectra for the powder flux at different temperatures.

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After subtracting the background, the spectrum was deconvolved using Gaussian line shapes for contributions from various structural units, as shown in Figure 7. Deconvolution of the Raman spectrum at RT without any crystallization is quite tricky due to the broad hump. Nevertheless, by referencing the 400 °C data (Figure 7a) at which the sample still possesses mainly a short-range ordered glassy structure according to the above HE-SXRD and PDF results, it still can be concluded qualitatively that the initial glassy network structure consists mainly of diffused Si–O–Si linkages associated with silicate-based glass at low frequencies (>600 cm–1) (46,47) and Al–O–B linkages at about 667 cm–1 (48,49) and between 650 and 750 cm–1, three [AlO4] structural units, Q2(Al) at 700–735 cm–1, Q3(Al) at 756–766 cm–1, and Q4(Al) at 792–802 cm–1, (50−52) and one symmetric stretching Q0(Si) of [SiO4] tetrahedra at ∼855 cm–1 between the region 670–900 cm-1, (53) and the orthoborate [BO3]3– group at ∼925 cm–1. (54) As the temperature increases, the Raman bands change in relative intensity. In addition, Raman bands located within the range of 440, 540, and 600 cm–1 were observed for the fitted Raman spectra acquired at 600, 700, 800 °C, and RTc. These bands could be linked with the Si–O–Si bending vibration of silica in the glass matrix. (46,47)

Figure 7

Figure 7. Deconvolution of in situ high-temperature Raman spectra for the powder flux at (a) 400 °C, (b) 600 °C, (c) 700 °C, (d) 800 °C, and (e) RTc after cooling down.

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It can be noticed from Figure 7 that an Al–O–Al band in the frequency region 492–508 cm–1 turns up at ∼600 °C and gets sharper at higher temperatures. The increased intensity of the peaks associated with Q2(Al), Q3(Al), and Q4(Al) from Al–O framework vibrations along with the temperature can also be observed. Correspondingly, the intensity of the Raman band corresponding to the Al–O–B bending vibration decreases, and the peak center shifts to a lower frequency (650 cm–1) during in situ measurements. The change from the glassy flux sample could be associated with the crystallization of aluminates, the Ca3Al2O6 and LiAlO2 phase, (52,55,56) as revealed by in situ HE-SXRD and PDF.
The intensity variation of the deconvoluted stretching vibration of isolated [SiO4] (Q0(Si)) Raman bands (in the range of 800–900 cm–1) can be attributed to the presence of the crystalline Ca2SiO4 phase (57) as the crystallization process continues with increasing temperatures. Similarly, a slight increase in the relative intensity of the band associated with the symmetric stretching vibration of the BO33– orthoborate unit can be linked to the presence of crystalline Ca3B2O6 (Figure 7). The addition of B2O3 reduces the viscosity of F-free CaO–Al2O3–SiO2-based mold fluxes (17) by forming boroxol rings with a [BO3]3– triangular structural unit. Table 2 summarizes the peak frequency and normalized integrated peak area of relevant bands of crystalline phases from deconvoluted Raman spectra assigned to network (bonds) structures at different temperatures.
Table 2. Relevant Structural Unit of Crystalline Phases and Corresponding Peak Frequency v (cm–1) Range, Normalized Integrated Peak Area (int. area), and Its Percentage (%) Obtained from the Deconvolution of Raman Spectra Acquired from the In Situ High-Temperature Measurements
  400 °C600 °C700 °C800 °CRTc
network structurev range (cm–1)int. area% areaint. area% areaint. area% areaint. area% areaint. area% area
Al–O–Al492–508  7921519602916713194734
Q2(Al)700–73540456311423621041335
Q3(Al)756–766110121007198451237871536
Q4(Al)792–80219722898179761449792308
Q0(Si)850–857259288541614092111422150218
[BO3]3–921–9303043310822111781715072880429

Discussion

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The heat treatment during in situ HE-SXRD measurement leaves about 50% Ca, 42% Al, 13% B, 51% Li, and 17% Si (in atom %) behind the glass matrix. This result indicates that the crystallization is not yet completed in the interior of the powder glass. For the crystallization incubation stages, the network structural units change, which do not alter the medium- and long-range disorder of the glass matrix. The crystallization is clearly a heterogeneous metastable process that increases the medium- and long-range order. It is apparent from Raman spectra (Figure 7) that the bands of Al–O–Al for LiAlO2, [BO3]3– associated with Ca3B2O6, and Q0(Si) attributable to Ca2SiO4 get stronger as the sample moves towards a more crystalline structure with increasing temperatures, also evidenced by the in situ HE-SXRD (Figure 3).
Based on the observations obtained in this work, the evolution sequence of crystalline phases in this glass over the temperature can be classified into several stages: (1) the incubation stage from RT to 400 °C, formation of (2) Ca3Al2O6 and Ca2SiO4 due to dehydration, (3) LiAlO2, and finally, (4) Ca3B2O6. In the first stage, changes in Raman spectra indicate a certain degree of local configurational rearrangement of the network structural units (Figure 7) without influencing the long-range disordered glassy matrix (Figure 5). Meanwhile, the crystalline Ca3Al2O6 and Ca2SiO4 are nucleated from their less ordered hydrate counterpart via
(3)
(4)
The presence of diffraction peaks of the glassy matrix in this temperature range manifests a fairly layered structure of the hydrates, agreeing with the literature. (35−37) Rapid increase in Ca3Al2O6 and Ca2SiO4 above 400 °C and the evolution of network structural units shown by Raman spectroscopy (Figure 7) imply that they can also nucleate as
(5)
(6)
(7)
The formation of LiAlO2 is probably via
(8)
The evolution of Ca3B2O6 in this glass is due to the reaction
(9)
An equilibrium among Q2, Q3, and Q4 structural units was found by Mysen et al. (58) during Raman investigation of binary alkali silicate liquid:
(10)
This reaction shifts to the right with a temperature increment. It is postulated that in aluminate glass and melts, a similar equilibrium among Q2(Al), Q3(Al), and Q4(Al) persists:
(11)
The equilibrium shift toward the right side of the reaction and the abundance of Q4(Al) could be evidenced by the increased Al–O–Al peak height at high temperatures and the increased area ratio of Q4(Al) to Q3(Al) from 600 to 800 °C in high-temperature Raman spectra.
In general, the crystallization process is thermally activated and controlled mainly by diffusion from bulk glass–ceramic to the glass–crystal interface. The introduction of alkali oxides, Li2O and Na2O, is meant to decrease the viscosity and provide more simple structural units, such as 2D [BO3]3–, Q0[SiO4], by reducing the degree of polymerization. (48,59) Such a modification facilitates the diffusion of ions; therefore, this investigated mold flux has a high potential to crystallize. The observed only one strong exothermic peak in DSC is attributed to the overlap of peaks from crystallization of different phases in a quite narrow temperature range, as illustrated by the in situ HE-SXRD and PDF analysis.

Conclusions

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The results of this study shed some light on the understanding of the crystallization phenomena in multi-component alumino-borosilicate glass, which make up of steel industrial wastes. The non-isothermal crystallization of the glass is investigated by in situ synchrotron X-ray diffraction, PDF, and Raman spectroscopy. The following conclusions can be drawn:

  • Crystallization of this glassy flux begins with the formation of Ca3Al2O6 and CaSiO4 followed by the precipitation of LiAlO2 and Ca3B2O6.

  • The nucleation mechanism of Ca3Al2O6 and CaSiO4 in the complex glass is triggered by the dehydration of corresponding hydrate phases, which has short-range order but long-range disorder, a fairly layered structure, and limited content in the glass matrix. This finding is further supplemented by the Raman results. Crystallization of subsequent LiAlO2 and Ca3B2O6 is strongly related to the changes of structural units during non-isothermal heating.

  • The nucleation of this complex multicomponent alumino-borosilicate glass is a heterogeneous metastable process and occurs in a quite narrow temperature range through the precipitation of multiple crystalline phases.

Author Information

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  • Corresponding Authors
  • Authors
    • Shubo Wang - Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland
    • Ekta Rani - Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland
    • Francis Gyakwaa - Process Metallurgy Research Unit, University of Oulu, Oulu FI-90014, Finland
    • Graham King - Canadian Light Source, 44 Innovation Blvd., Saskatoon, Saskatchewan S7N 2V3, Canada;  Orcidhttps://orcid.org/0000-0003-1886-7254
    • Wei Cao - Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland;  Orcidhttps://orcid.org/0000-0003-3139-1780
    • Marko Huttula - Nano and Molecular Systems Research Unit, University of Oulu, Oulu FI-90014, Finland
    • Timo Fabritius - Process Metallurgy Research Unit, University of Oulu, Oulu FI-90014, Finland
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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The authors gratefully acknowledge the financial support of Academy of Finland grant #311934. High-energy synchrotron X-ray scattering experiments described in this paper were performed at the Canadian Light Source, a national research facility of the University of Saskatchewan, which is supported by the Canada Foundation for Innovation (CFI), the Natural Sciences and Engineering Research Council (NSERC), the National Research Council (NRC), the Canadian Institutes of Health Research (CIHR), the Government of Saskatchewan, and the University of Saskatchewan.

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This article references 59 other publications.

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    Thermal stability and crystallization kinetics of MgO-Al2O3-B2O3-SiO2 glasses
    Reben, Manuela; Li, Hong
    International Journal of Applied Glass Science (2011), 2 (2), 96-107CODEN: IJAGD4; ISSN:2041-1294. (Wiley-Blackwell)
    To support commercialization of the MgO-Al2O3-B2O-SiO2-based low-dielec. glass fibers, crystn. characteristics of the relevant glasses was investigated under various heat-treatment conditions. The study focused on the effects of iron on the related thermal properties and crystn. kinetics. Both air-cooled and nucleation-treated samples were characterized by using the DTA/differential scanning calorimeter method between room temp. and 1200°C. A collected set of properties covers glass transition temp. (Tg), max. crystn. temp. (Tp), sp. heat (ΔCp), enthalpy of crystn. (ΔHcryst), and thermal stability (ΔT = Tp-Tg). Using the Kinssiger method, the activation energy of crystn. was detd. Cryst. phases in the samples having various thermal histories were detd. using powder X-ray diffraction (XRD) and/or in situ high-temp. XRD method. Selective scanning electron microscope/energy-dispersive spectroscopy anal. provided evidence that crystal d. in the glass is affected by the iron concn. Glass network structures, for air-cooled and heat-treated samples, were examd. using a midinfrared spectroscopic method. Combining all of the results from our study, iron in glass is believed to function as a nucleation agent enhancing crystal population d. in the melt without altering a primary phase field. By comparing the XRD data of the glasses in two forms (bulk vs. powder), the following conclusions can be reached. The low-dielec. glass melt in com. operation should be resistant to crystn. above 1100°C. Microscopic amorphous phase sepn., possibly a borate-enriched phase sepg. from the silicate-enriched continuous phase can occur only if the melt is held at temps. below 1100°C, i.e., below the glass immiscibility temp. The study concludes that neither crystn. nor amorphous phase sepn. will be expected for drawing fibers between 1200°C and 1300°C in a com. operation.
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    Hyun, S. H.; Cho, J. W. Heat Transfer Control by Dispersed Metallic Particles in Glassy Mold Flux Film for Continuous Steel Casting. J. Am. Ceram. Soc. 2020, 103, 5678– 5687,  DOI: 10.1111/jace.17294
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    Heat transfer control by dispersed metallic particles in glassy mold flux film for continuous steel casting
    Hyun, Sung-Hee; Cho, Jung-Wook
    Journal of the American Ceramic Society (2020), 103 (10), 5678-5687CODEN: JACTAW; ISSN:0002-7820. (Wiley-Blackwell)
    To assess the effect of metallic particles (MPs) on heat transfer in glassy mold flux, a structurally stable glassy mold flux system composed of CaO-Al2O3-CaF2 was examd. with 0, 2, or 5 wt% of FeO or Fe MPs. The change of extinction coeff. by Mie Scattering of the Fe particles and absorption by FeO was quantified using Fourier transformation IR ray spectroscopy and an UV/Visible spectrometry. Thermal cond. of mold flux film with dispersed MPs was quantified using laser flash technique. One-dimensional Debye temp. was calcd., and particle morphol. and size distribution were obsd. using image anal. to explain variations in thermal cond. among the glass samples. Finally, to simulate the heat transfer ratio by both the conduction and radiation, the actual heat flux through mold flux film was measured using an IR Emitter Technique. The overall heat transfer rate across liq. flux film could be reduced significantly by a dispersion of MPs.
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    Choi, S. Y.; Lee, D. H.; Shin, D. W.; Choi, S. Y.; Cho, J. W.; Park, J. M. Properties of F-Free Glass System as a Mold Flux: Viscosity, Thermal Conductivity and Crystallization Behavior. In Journal of Non-Crystalline Solids; North-Holland: 2004; Vol. 345-346, pp. 157– 160.
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    Mizuno, H.; Esaka, H.; Shinozuka, K.; Tamura, M. Analysis of the Crystallization of Mold Flux for Continuous Casting of Steel. ISIJ Int. 2008, 48, 277– 285,  DOI: 10.2355/isijinternational.48.277
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    Analysis of the crystallization of mold flux for continuous casting of steel
    Mizuno, Hidenori; Esaka, Hisao; Shinozuka, Kei; Tamura, Manabu
    ISIJ International (2008), 48 (3), 277-285CODEN: IINTEY; ISSN:0915-1559. (Iron and Steel Institute of Japan)
    In continuous casting of steel, mold fluxes are used to prevent surface defects, such as longitudinal cracks. The crystn. of mold flux promotes mild cooling of the steel shell, but crystn. behavior has been still uncertain. Therefore, this study has been carried out to analyze the crystn. processes of mold flux. Mold flux used in this study has high tendency for crystn. Quenched specimens were heat-treated in various conditions and characterized. Glassy specimen heat-treated in the elec. furnace over 550°C for 180 min crystd. These cryst. were confirmed to be cuspidine by XRD anal. The no. of grains decreased and the av. grain size increased with rise of temp. of heat treatment. The growth velocity also increased with rise of temp. In-situ observation by the laser microscope revealed that the glassy specimen crystd. in a moment over 600°C and the surface of the specimen turned to be rough. This may lead to mild cooling in the mold.
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    Kawamoto, M.; Tsukaguchi, Y.; Nishida, N.; Kanazawa, T.; Hiraki, S. Improvement of the Initial Stage of Solidification by Using Mild Cooling Mold Powder*. ISIJ Int. 1997, 37, 134– 139,  DOI: 10.2355/ISIJINTERNATIONAL.37.134
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    Improvement of the initial stage of solidification by using mild cooling mold powder
    Kawamoto, Masayuki; Tsukaguchi, Yuichi; Nishida, Norihiro; Kanazawa, Takashi; Hiraki, Sei
    ISIJ International (1997), 37 (2), 134-139CODEN: IINTEY; ISSN:0915-1559. (Iron and Steel Institute of Japan)
    The initial stage of solidification for continuous casting is important in optimizing the surface quality of steel. It is well known that hypo-peritectic steel has problems with longitudinal cracking due to shrinkage resulting from the δ→γ transformation. High speed continuous casting, with a speed range of 4-5 m/min, a disadvantage with regard to longitudinal cracking. In this study, mild cooling mold powders were developed to improve the surface quality of high speed casting slabs and round-billets. The results can be summarized as follows; (1) High CaO/SiO2 ratio mold powder with a high solidification temp. is most suitable for a slab caster. (2) Low CaO/SiO2 ratio mold powder with a high solidification temp. is most suitable for a round billet caster. (3) The effect of radiation in liq. powder film is bigger than solid powder film.
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    Rüssel, C. Nanocrystallization of CaF2 from Na2O/K2O/CaO/CaF2/Al2O3/SiO2 Glasses. Chem. Mater. 2005, 17, 5843– 5847,  DOI: 10.1021/CM051430X
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    Nanocrystallization of CaF2 from Na2O/K2O/CaO/CaF2/Al2O3/SiO2 Glasses
    Ruessel, Christian
    Chemistry of Materials (2005), 17 (23), 5843-5847CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)
    In glasses with compn. (100-x)(9.9Na2O·8.8K2O·12.1CaO·6.6Al2O3·62SiO2)·xCaF2 the glass-transition temp. decreases with increasing CaF2 concn. Samples with x = 12.5 were thermally treated at 520-560 °C for 1-80 h, leading to crystn. of CaF2. The quantity of cryst. CaF2 increases with increasing crystn. temp., while the mean crystallite size remains const. The glass-transformation temp. of partially crystd. samples increases with increasing crystn. temp. and crystn. time and approaches a value equal to the temp. at which the samples were treated. This was explained by formation of a highly viscous layer enriched in SiO2 formed during crystn., which acts as a diffusion barrier and hinders further crystal growth.
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    Banijamali, S.; Rezaei, H. R.; Eftekhari Yekta, B.; Marghussian, V. K. Sinterability, Crystallization and Properties of Glass-Ceramic Tiles Belonging to CaF2-CaO-MgO-Al2O3-SiO2 System. Ceram. Int. 2007, 33, 1557– 1561,  DOI: 10.1016/j.ceramint.2006.06.004
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    Sinterability, crystallization and properties of glass-ceramic tiles belonging to CaF2-CaO-MgO-Al2O3-SiO2 system
    Banijamali, S.; Rezaei, H. R.; Eftekhari Yekta, B.; Marghussian, V. K.
    Ceramics International (2007), 33 (8), 1557-1561CODEN: CINNDH; ISSN:0272-8842. (Elsevier Ltd.)
    The effect of CaO substitution by different amts. of MgO on crystn. and various properties of CaF2-CaO-Al2O3-SiO2 glass system were investigated. It was shown that the properties of obtained glass-ceramics are greatly influenced by MgO contents. The Avrami exponent and activation energy for crystn. of the most promising and the MgO-free specimens were detd. Results suggested that surface crystn. was the main pptn. mechanism of both samples and while the activation energy for crystn. of MgO contg. sample was less than MgO-free one, its ability to crystallize was diminished. SEM results confirm occurrence of surface crystn. of samples and depicts the phenomenon of microstructure coarsening by increasing MgO content and also reduced densification of specimen with magnesium oxide more than 9 wt.%.
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    Li, J. L.; Shu, Q. F.; Chou, K. Effect of Al2O3/SiO2 Mass Ratio on Viscosity of CaO–Al2O3–SiO2–CaF2 Slag. Ironmaking Steelmaking 2015, 42, 154– 160,  DOI: 10.1179/1743281214Y.0000000225
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    Effect of Al2O3/SiO2 mass ratio on viscosity of CaO-Al2O3-SiO2-CaF2 slag
    Li, J. L.; Shu, Q. F.; Chou, K.
    Ironmaking & Steelmaking (2015), 42 (2), 154-160CODEN: IMKSB7; ISSN:0301-9233. (Maney Publishing)
    Recently, high Al steel has received increasing attention due to the perfect combination of strength to wt. ratio and excellent ductility. The high amt. of Al in the steel may cause great change on the chem. compns. of mold fluxes due to chem. reactions between SiO2 in the mold fluxes and Al in the steel, thereby influencing the phys. properties of the mold fluxes. Although many researches have reported on the effect of Al2O3/SiO2 mass ratio [w(Al2O3)/w(SiO2)] on the viscosity of mold fluxes, there is still a lot of controversies. In this work, the effect of w(Al2O3)/w(SiO2), which is in a large range of 0·22-1·75, on the viscosity of CaO-Al2O3-SiO2-CaF2 system as a base system for mold fluxes was investigated by the rotating cylinder method. The results showed that the viscosity of CaO-Al2O3-SiO2-CaF2 system first decreases and then increases as w(Al2O3)/w(SiO2) increases from 0·22 to 1·75. The viscosity values of CaO-Al2O3-SiO2-CaF2 system were also calcd. by employing various viscosity models. Comparisons between calcd. viscosity values and exptl. data have shown that values calcd. by Factsage and modified Riboud model were more close to the exptl. values than other models and values calcd. by the Riboud model and Shu model were much smaller than the exptl. values. X-ray diffraction (XRD) analyses on the samples after the viscosity measurement indicate that there were two kinds of cryst. phase, CaF2 and gehlenite (Ca2Al2SiO7) in all fluxes and gehlenite increases with increase of w(Al2O3)/w(SiO2).
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  10. 10
    Mukherjee, D. P.; Das, S. K. SiO2–Al2O3–CaO Glass-Ceramics: Effects of CaF2 on Crystallization, Microstructure and Properties. Ceram. Int. 2013, 39, 571– 578,  DOI: 10.1016/J.CERAMINT.2012.06.066
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    SiO2-Al2O3-CaO glass-ceramics: Effects of CaF2 on crystallization, microstructure and properties
    Mukherjee, Debasis Pradip; Das, Sudip Kumar
    Ceramics International (2013), 39 (1), 571-578CODEN: CINNDH; ISSN:0272-8842. (Elsevier Ltd.)
    The effects of fluorine content on the nucleation and crystn. behavior of SiO2-Al2O3-CaO glass ceramics system have been investigated. The cryst. phases were detd. by X-ray diffraction (XRD). The crystn. kinetics was detd. by DTA (DTA). The microstructures were examd. by using scanning electron microscope (SEM). Fourier transformed IR spectra (FTIR) anal. was used to study the glass structure. The results showed that by increasing the fluorine content, both the crystn. peak temp. (Tp) and activation energy (E) decreased. Wollastonite, anorthite and gehlenite are the main cryst. phases that exist in the glass ceramics system. The study shows that fluorine promoted initial crystn. of glass and can be used as an effective nucleating agent in the SiO2-Al2O3-CaO system.
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  11. 11
    Shahbazian, F.; Sichen, D.; Mills, K. C.; Seetharaman, S. Experimental Studies of Viscosities of Some CaO-CaF2-SiO2 Slags. Ironmaking Steelmaking 1999, 26, 193– 199,  DOI: 10.1179/030192399677068
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    Experimental studies of viscosities of some CaO-CaF2-SiO2 slags
    Shahbazian, F.; Sichen, Du; Mills, K. C.; Seetharaman, S.
    Ironmaking and Steelmaking (1999), 26 (3), 193-199CODEN: IMKSB7; ISSN:0301-9233. (IOM Communications Ltd.)
    In the present work, the viscosities of some CaO-CaF2-SiO2 slags were measured using the rotating cylinder method. The effects of various volatile fluorine compds. on the change in slag compn. are discussed on the basis of thermodn. calcns. The kinetic factors concerning the escape of the volatile fluorides under the exptl. conditions were also examd. It was found that the formation of gaseous species SiF4 was the main source for compositional changes during the viscosity measurements. In the case of CaO-CaF2-SiO2 slags, the formation of SiF4 would be somewhat limited owing to the existence of CaO. The compn. change during the measurements was only about ± 1 wt-% for all components in most cases. Viscosity measurements are reported for slags, based on the post-measurement compns. It was found that the addn. of CaF2 causes a significant decrease in viscosity.
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  12. 12
    Wei, J.; Wang, W.; Zhou, L.; Huang, D.; Zhao, H.; Ma, F. Effect of Na2O and B2O3 on the Crystallization Behavior of Low Fluorine Mold Fluxes for Casting Medium Carbon Steels. Metall. Mater. Trans. B 2014, 45, 643– 652,  DOI: 10.1007/s11663-013-9957-y
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    12
    Effect of Na2O and B2O3 on the crystallization behavior of low fluorine mold fluxes for casting medium carbon steels
    Wei, Juan; Wang, Wanlin; Zhou, Lejun; Huang, Daoyuan; Zhao, Huan; Ma, Fanjun
    Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science (2014), 45 (2), 643-652CODEN: MTBSEO; ISSN:1073-5615. (Springer)
    An investigation was conducted to study the effect of Na2O and B2O3 on the crystn. behavior of low F mold powders for casting medium C (MC) steels. B2O3 tends to lower the crystn. temp. and increase crystn. incubation time of the low F powders; however, Na2O plays an opposite role compared with that of B2O3. The cryst. phase of Ca11Si4B2O22 was formed in Sample D2 [F = 3 pct, Na2O = 10 pct, B2O3 = 8 pct (in wt pct)], which exhibited the most similar crystn. behavior to that of cuspidine, such that Sample D2 showed closest crystn. kinetics to that of a conventional high-F mold slag for casting MC steels. The pptd. cryst. phases for all the samples were analyzed and discussed.
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    Kieffer, J.; Wright, J. P. PyFAI: A Python Library for High Performance Azimuthal Integration on GPU. In Powder Diffraction; Cambridge University Press, 2013; Vol. 28, pp. S339– S350,  DOI: 10.1017/S0885715613000924 .
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    Grajcar, A.; Kuziak, R.; Zalecki, W. Third Generation of AHSS with Increased Fraction of Retained Austenite for the Automotive Industry. Arch. Civ. Mech. Eng. 2012, 12, 334– 341,  DOI: 10.1016/J.ACME.2012.06.011
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    Kim, M. S.; Lee, S. W.; Cho, J. W.; Park, M. S.; Lee, H. G.; Kang, Y. B. A Reaction between High Mn-High Al Steel and CaO-SiO2-Type Molten Mold Flux: Part I. Composition Evolution in Molten Mold Flux. Metall. Mater. Trans. B 2013, 44, 299– 308,  DOI: 10.1007/s11663-012-9770-z
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    A Reaction Between High Mn-High Al Steel and CaO-SiO2-Type Molten Mold Flux: Part I. Composition Evolution in Molten Mold Flux
    Kim, Min-Su; Lee, Su-Wan; Cho, Jung-Wook; Park, Min-Seok; Lee, Hae-Geon; Kang, Youn-Bae
    Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science (2013), 44 (2), 299-308CODEN: MTBSEO; ISSN:1073-5615. (Springer)
    In order to elucidate the reaction mechanism between high Mn-high Al steel such as twin-induced plasticity steel and molten mold flux composed mainly of CaO-SiO2 during continuous casting process, a series of lab.-scale expts. were carried out in the present study. Molten steel and molten flux were brought to react in a refractory crucible in a temp. range between 1713 K to 1823 K (1440 °C to 1550 °C) and compn. evolution in the steel and the flux was analyzed using inductively coupled plasma at. emission spectroscopy, X-ray fluorescence, and electron probe microanal. The amt. of SiO2 in the flux was significantly reduced by Al in the steel; thus, Al2O3 was accumulated in the flux as a result of a chem. reaction, 4[Al] + 3(SiO2) = 3[Si] + 2(Al2O3). In order to find a major factor which governs the reaction, a no. of factors ((pct CaO/pct SiO2), (pct Al2O3), [pct Al], [pct Si], and temp.) were varied in the expts. It was found that the above chem. reaction was mostly governed by [pct Al] in the molten steel. Temp. had a mild effect on the reaction. On the other hand, (pct CaO/pct SiO2), (pct Al2O3), and [pct Si] did not show any noticeable effect on the reaction. Apart from the above reaction, the following reactions are also thought to happen simultaneously: 2[Mn] + (SiO2) = [Si] + 2(MnO) and 2[Fe] + (SiO2) = [Si] + 2(FeO). These oxide components were subsequently reduced by Al in the molten steel. Na2O in the molten flux was gradually decreased and the decrease was accelerated by increasing [pct Al] and temp. Possible reactions affecting the Al2O3 accumulation are summarized.
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    Cho, J.-W.; Blazek, K.; Frazee, M.; Yin, H.; Park, J. H.; Moon, S.-W. Assessment of CaO–Al2O3 Based Mold Flux System for High Aluminum TRIP Casting. ISIJ Int. 2013, 53, 62– 70,  DOI: 10.2355/ISIJINTERNATIONAL.53.62
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    16
    Assessment of CaO-Al2O3 based mold flux system for high aluminum TRIP casting
    Cho, Jung-Wook; Blazek, Kenneth; Frazee, Michael; Yin, Hongbin; Park, Jeong Hyouk; Moon, Sang-Woon
    ISIJ International (2013), 53 (1), 62-70CODEN: IINTEY; ISSN:0915-1559. (Iron and Steel Institute of Japan)
    Today, the demands for Advanced High Strength Steels (AHSS) have gradually increased due to their ability to reduce vehicle wt. as a means to save energy, reduce the environmental impact while simultaneously improving passenger safety. However, AHSS often require the addn. of large amts. of alloying elements such as aluminum and this can make it difficult to cast sound slabs without surface defects. When casting high aluminum AHSS, due to the reaction between aluminum in steel and silica in mold flux, the viscosity and crystn. characteristics of the mold slag changes drastically, and deteriorates mold lubrication. Therefore, it is crit. to limit the reaction between Al in steel and mold slag and at the same time to provide consistent and adequate mold slag in-use properties. This paper describes the development of non-traditional lime-alumina based mold fluxes which have the potential to reduce slag-steel interaction during casting of high aluminum TRIP steel. Several trial casts of 1.45% Al TRIP steel have been conducted on a pilot caster to examine the performance of mold fluxes developed. When the lime-alumina based mold fluxes were applied successfully, alumina pickup was reduced to less than 5% as compared to 15% alumina pickup for corollary trial casts using conventional lime-silica mold fluxes. The developed lime-alumina mold fluxes showed improved in-mold performance as indicated by enhanced lubrication and stable mold heat transfer, again compared to lime-silica fluxes. Cast slabs from the trials using these lime-alumina fluxes have periodic and sound oscillation marks and minimized defects.
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    Li, J.; Kong, B.; Galdino, B.; Xu, J.; Chou, K.; Liu, Q.; Shu, Q. Investigation on Properties of Fluorine-Free Mold Fluxes Based on CaO–Al2O3–B2O3 System. Steel Res. Int. 2017, 88, 1600485,  DOI: 10.1002/srin.201600485
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    Heulens, J.; Blanpain, B.; Moelans, N. Analysis of the Isothermal Crystallization of CaSiO3 in a CaO-Al2O3-SiO2 Melt through in Situ Observations. J. Eur. Ceram. Soc. 2011, 31, 1873– 1879,  DOI: 10.1016/j.jeurceramsoc.2011.03.038
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    Analysis of the isothermal crystallization of CaSiO3 in a CaO-Al2O3-SiO2 melt through in situ observations
    Heulens, J.; Blanpain, B.; Moelans, N.
    Journal of the European Ceramic Society (2011), 31 (10), 1873-1879CODEN: JECSER; ISSN:0955-2219. (Elsevier Ltd.)
    Crystal growth of Wollastonite (CaO.SiO2) in a 42CaO-10Al2O3-48SiO2 melt is obsd. in situ at 1320°C and 1370°C using a high-temp. confocal scanning laser microscope (CSLM). The crystn. is initiated by seeding the melt with Wollastonite particles, which is the primary phase at these temps. and compn. At 1370°C, a faceted growth form is obsd., while at 1320°C, dendritic, nonfaceted growth occurs. The dendrite tip velocity is measured and compared with Ivantsov's theory. The presented exptl. technique proofs to be successful for characterizing isothermal crystn. of minerals in silicate melts.
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    Wang, Z.; Shu, Q.; Chou, K. Crystallization Kinetics of CaO-SiO2(CaO/SiO2=1)-TiO2-10 Mass%B2O3 Glassy Slag by Differential Thermal Analysis. ISIJ Int. 2015, 55, 709– 716,  DOI: 10.2355/isijinternational.55.709
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    Crystallization kinetics of CaO-SiO2(CaO/SiO2 = 1)-TiO2-10 mass%B2O3 glassy slag by differential thermal analysis
    Wang, Zhen; Shu, Qifeng; Chou, Kuochih
    ISIJ International (2015), 55 (4), 709-716CODEN: IINTEY; ISSN:0915-1559. (Iron and Steel Institute of Japan)
    Crystn. characteristics of the CaO-SiO2-TiO2-10%B2O3 glassy slag at w(CaO)/w(SiO2) = 1 have been studied by DTA (DTA) and Matusita-Sakka method. Crystn. products have been distinguished by employing X-ray diffraction (XRD) and SEM equipped with Energy Dispersive Spectroscopy (SEM-EDS). As the TiO2 content is within 10-18%, the crystal phase pptd. is mainly CaSiO3, and the effective activation energies for crystal growth increase with the increase of TiO2 content. Crystn. mechanism for CaSiO3 shifted from surface crystn. to onedimensional growth with increase of TiO2. As the TiO2 content in slag further increases to 22% and 26%, CaTiSiO5 becomes the predominant crystal phase pptd., and the effective activation energies for crystal growth decrease with the increase of TiO2 content. Crystn. mechanism for CaTiSiO5 is mainly surface crystn. Therefore, with the increase of TiO2 content, the crystn. ability of the CaO-SiO2-TiO2-10%B2O3 glass system decreases initially and then increases.
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  20. 20
    Pena, R. B.; Sampaio, D. V.; Lancelotti, R. F.; Cunha, T. R.; Zanotto, E. D.; Pizani, P. S. In-Situ Raman Spectroscopy Unveils Metastable Crystallization in Lead Metasilicate Glass. J. Non-Cryst. Solids 2020, 546, 120254,  DOI: 10.1016/J.JNONCRYSOL.2020.120254
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    20
    In-situ Raman spectroscopy unveils metastable crystallization in lead metasilicate glass
    Pena, R. B.; Sampaio, D. V.; Lancelotti, R. F.; Cunha, T. R.; Zanotto, E. D.; Pizani, P. S.
    Journal of Non-Crystalline Solids (2020), 546 (), 120254CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
    The formation of metastable phases is a relevant, challenging and yet underexplored subject in glass crystn. In this work, we examd. the isothermal crystn. of PbO. SiO2 lead metasilicate glass by using in-situ Raman spectroscopy. We provide evidence for the evolution process from the glass to alamosite, the stable cryst. phase, which is intermediated by two distinct metastable phases at different temps. At 550°C the crystn. pathway proceeded from the low PbSiO3 to alamosite, whereas at 600°C the cryst. phase evolved from the hexagonal PbSiO3 to alamosite. We found no interconversion between these two metastable phases, indicating that both can ppt. prior to alamosite stabilization. These findings demystify the alleged complexity of the crystn. process of lead metasilicate glass, raised in the literature, whose data are critically analyzed and discussed herein.
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  21. 21
    Wang, W.; Xu, H.; Zhai, B.; Zhang, L. A Review of the Melt Structure and Crystallization Behavior of Non-Reactive Mold Flux for the Casting of Advanced High-Strength Steels. Steel Research International; John Wiley & Sons, Ltd 2021, p 2100073.
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    Liu, J.; Yang, K.; Zhai, J.; Shen, B. Effects of Crystallization Temperature on Phase Evolution and Energy Storage Properties of BaO-Na2O-Nb2O5-SiO2-Al2O3 Glass-Ceramics. J. Eur. Ceram. Soc. 2018, 38, 2312– 2317,  DOI: 10.1016/J.JEURCERAMSOC.2018.01.003
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    Effects of crystallization temperature on phase evolution and energy storage properties of BaO-Na2O-Nb2O5-SiO2-Al2O3 glass-ceramics
    Liu, Jingran; Yang, Ke; Zhai, Jiwei; Shen, Bo
    Journal of the European Ceramic Society (2018), 38 (5), 2312-2317CODEN: JECSER; ISSN:0955-2219. (Elsevier Ltd.)
    Barium sodium niobate (BNN) glass ceramics were successfully fabricated with controllable crystn. by technol. for heating processing and the effects of crystn. temps. on phase evolution, microstructure, dielec. properties and breakdown strength were investigated systematically. In addn., the empirical power-law dependence of breakdown strength on thickness (Ebαd-n) was confirmed in BNN glass-ceramic system with an exponent n of 0.21. Based on the results, the BNN glass ceramic crystd. at 800°C presents a remarkable breakdown strength (BDS) of 2322kV/cm with the tested thickness of 30μm, and the highest energy d. of 16.6J/cm3 was achieved.
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  23. 23
    Singh, H.; Shu, Q.; King, G.; Liang, Z.; Wang, Z.; Cao, W.; Huttula, M.; Fabritius, T. Structure and Viscosity of CaO–Al2O3–B2O3–BaO Slags with Varying Mass Ratio of BaO to CaO. J. Am. Ceram. Soc. 2021, 104, 4505– 4517,  DOI: 10.1111/JACE.17877
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    23
    Structure and viscosity of CaO-Al2O3-B2O3-BaO slags with varying mass ratio of BaO to CaO
    Singh, Harishchandra; Shu, Qifeng; King, Graham; Liang, Ziqing; Wang, Zhifeng; Cao, Wei; Huttula, Marko; Fabritius, Timo
    Journal of the American Ceramic Society (2021), 104 (9), 4505-4517CODEN: JACTAW; ISSN:0002-7820. (Wiley-Blackwell)
    The structure of CaO-Al2O3-B2O3-BaO glassy slags with varying mass ratio of BaO to CaO has been investigated by Raman spectroscopy, 11B and 27Al magic angle spinning NMR (MAS-NMR) spectroscopy and at. pair distribution function (PDF). 11B MAS-NMR spectra reveal the dominant coordination of boron as trigonal. Both simulations on 11B MAS-NMR spectra and Raman spectroscopy indicate the presence of orthoborate as the primary borate group with a few borate groups with one bridging oxygen and minor four-coordinated boron sites. 27Al MAS-NMR and PDF show the Al coordination as tetrahedral. Raman spectral study shows that the transverse vibration of AlIV-O-AlIV and AlIV-O-BIII, stretching vibration of aluminate structural units and vibration of orthoborate and pyroborate structural groups. A broader distribution of Al-O bond lengths in PDF also supports the enhanced network connectivity. Viscosity measurements show the increase in viscosity of molten slags with increasing mass ratio of BaO to CaO, which further attributes to the enhanced d.p. of the aluminate network.
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    Shu, Q.; Klug, J. L.; Li, Q. Non-Isothermal Melt Crystallization Kinetics for CaO–Al2O3–B2O3 F-Free Mould Fluxes. ISIJ Int. 2019, 59, 1057– 1063,  DOI: 10.2355/ISIJINTERNATIONAL.ISIJINT-2018-677
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    24
    Non-isothermal melt crystallization kinetics for CaO-Al2O3-B2O3 F-free mould fluxes
    Shu, Qifeng; Klug, Jeferson Leandro; Li, Qiangqi
    ISIJ International (2019), 59 (6), 1057-1063CODEN: IINTEY; ISSN:0915-1559. (Iron and Steel Institute of Japan)
    Efforts have been made to develop fluorine-free mold fluxes for the continuous casting of steel process. In this work the crystn. behavior of fluorine-free mold slags based on the CaO-Al2O3-B2O3 system was investigated by differential scanning calorimeter (DSC) and SEM equipped with energy dispersive spectroscopy(SEM-EDS). The crystn. kinetics for Ca3Al2O6 primary crystals was analyzed by combining modified Avrami anal. with Friedman isoconversional method. Avrami parameter n is close to 4 for samples with the ratios w(CaO)/w(Al2O3) = 1 and w(CaO)/w(Al2O3) = 1.2, indicating a crystn. mechanism of continuous bulk nucleation and 3D crystal growth. The Avrami parameter n for samples with w(CaO)/w(Al2O3) = 0.9 is close to 3, indicating instantaneous bulk nucleation and 3D crystal growth. The crystn. rate const. is the highest and half crystn. time is the lowest for the samples with w(CaO)/w(Al2O3) = 0.9, indicating the fastest crystn. In the initial stage, effective activation energies were mainly detd. by the undercooling values. In the final stage, kinetic barrier for crystn. could have some influence on crystn.; for the investigated mold fluxes crystn. in the final stage is retarded by increasing w(CaO)/w(Al2O3) ratio. Thus crystn. mechanisms were elucidated and effective activation energy of crystn. for the first crystal which ppts. from melt was detd.
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    Gomez, A.; Dina, G.; Kycia, S. The High-Energy x-Ray Diffraction and Scattering Beamline at the Canadian Light Source. Rev. Sci. Instrum. 2018, 89, 063301  DOI: 10.1063/1.5017613
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    The high-energy x-ray diffraction and scattering beamline at the Canadian Light Source
    Gomez, A.; Dina, G.; Kycia, S.
    Review of Scientific Instruments (2018), 89 (6), 063301/1-063301/8CODEN: RSINAK; ISSN:0034-6748. (American Institute of Physics)
    The optical design for the high-energy x-ray diffraction and scattering beamline of the Brockhouse sector at the Canadian Light Source is described. The design is based on a single side-bounce silicon focusing monochromator that steers the central part of a high-field permanent magnet wiggler beam into the exptl. station. Two different configurations are proposed: a higher energy resoln. with vertical focusing and a lower energy resoln. with horizontal and vertical focusing. The monochromator will have the possibility of mounting three crystals: one crystal optimized for 35 keV that focuses in the horizontal and vertical directions using reflection (1,1,1) and two other crystals both covering the energies above 40 keV: one with only vertical focusing and another one with horizontal and vertical focusing. The geometry of the last two monochromator crystals was optimized to use reflections (4,2,2) and (5,3,3) to cover the broad energy range from 40 to 95 keV. (c) 2018 American Institute of Physics.
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    Chupas, P. J.; Chapman, K. W.; Kurtz, C.; Hanson, J. C.; Lee, P. L.; Grey, C. P. A Versatile Sample-Environment Cell for Non-Ambient X-Ray Scattering Experiments. J. Appl. Crystallogr. 2008, 41, 822– 824,  DOI: 10.1107/S0021889808020165
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    A versatile sample-environment cell for non-ambient X-ray scattering experiments
    Chupas, Peter J.; Chapman, Karena W.; Kurtz, Charles; Hanson, Jonathan C.; Lee, Peter L.; Grey, Clare P.
    Journal of Applied Crystallography (2008), 41 (4), 822-824CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)
    A compact reaction cell is described for in-situ expts. requiring control of both the temp. of the sample and the atm. over the sample. The cell incorporates an optional furnace capable of temps. of up to ∼1273 K. The compact design and ability of the cell to mount directly on a std. goniometer head allows portability to a large no. of diffraction instruments at synchrotron sources.
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    Toby, B. H.; Von Dreele, R. B. GSAS-II: The Genesis of a Modern Open-Source All Purpose Crystallography Software Package. J. Appl. Crystallogr. 2013, 46, 544– 549,  DOI: 10.1107/S0021889813003531
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    GSAS-II: the genesis of a modern open-source all purpose crystallography software package
    Toby, Brian H.; Von Dreele, Robert B.
    Journal of Applied Crystallography (2013), 46 (2), 544-549CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)
    The newly developed GSAS-II software is a general purpose package for data redn., structure soln. and structure refinement that can be used with both single-crystal and powder diffraction data from both neutron and x-ray sources, including lab. and synchrotron sources, collected on both two- and 1-dimensional detectors. It is intended that GSAS-II will eventually replace both the GSAS and the EXPGUI packages, as well as many other utilities. GSAS-II is open source and is written largely in object-oriented Python but offers speeds comparable to compiled code because of its reliance on the Python NumPy and SciPy packages for computation. It runs on all common computer platforms and offers highly integrated graphics, both for a user interface and for interpretation of parameters. The package can be applied to all stages of crystallog. anal. for const.-wavelength x-ray and neutron data. Plans for considerable addnl. development are discussed.
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    He, B. B. Two-Dimensional X-Ray Diffraction; John Wiley & Sons, Inc., 2018.
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    Toraya, H. A New Method for Quantitative Phase Analysis Using X-Ray Powder Diffraction: Direct Derivation of Weight Fractions from Observed Integrated Intensities and Chemical Compositions of Individual Phases. J. Appl. Crystallogr. 2016, 49, 1508– 1516,  DOI: 10.1107/S1600576716010451
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    A new method for quantitative phase analysis using X-ray powder diffraction: direct derivation of weight fractions from observed integrated intensities and chemical compositions of individual phases
    Toraya, Hideo
    Journal of Applied Crystallography (2016), 49 (5), 1508-1516CODEN: JACGAR; ISSN:1600-5767. (International Union of Crystallography)
    A new method for the quant. phase anal. of multi-component polycryst. materials using the X-ray powder diffraction technique is proposed. A formula for calcg. wt. fractions of individual cryst. phases has been derived from the intensity formula for powder diffraction in Bragg-Brentano geometry. The integrated intensity of a diffraction line is proportional to the vol. fraction of a relevant cryst. phase in an irradiated sample, and the vol. fraction, when it is multiplied with the chem. formula wt., can be related to the wt. fraction. The structure-factor-related quantity in the intensity formula, when it is summed in an adequate 2θ range, can be replaced with the sum of squared nos. of electrons belonging to composing atoms in the chem. formula. Unit-cell vols. and the no. of chem. formula units are all cancelled out in the formula. Therefore, the formula requires only single-measurement integrated intensity datasets for the individual phases and their chem. compns. No std. ref. material, ref. intensity ratio or crystal structure parameter is required. A new procedure for partitioning the intensities of unresolved overlapped diffraction lines has also been proposed. It is an iterative procedure which starts from derived wt. fractions, converts the wt. fractions to vol. fractions by utilizing addnl. information on material densities, and then partitions the intensities in proportion to the vol. fractions. Use of the Pawley pattern decompn. method provides more accurate intensity datasets than the individual profile fitting technique, and it expands the applicability of the present method to more complex powder diffraction patterns. Test results using weighed mixt. samples showed that the accuracy, evaluated by the root-mean-square error, is comparable to that obtained by Rietveld quant. phase anal.
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    Tian, K. V.; Yang, B.; Yue, Y.; Bowron, D. T.; Mayers, J.; Donnan, R. S.; Dobó-Nagy, C.; Nicholson, J. W.; Fang, D. C.; Greer, A. L.; Chass, G. A.; Greaves, G. N. Atomic and Vibrational Origins of Mechanical Toughness in Bioactive Cement during Setting. Nat. Commun. 2015, 6, 1– 10,  DOI: 10.1038/ncomms9631
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    Zheng, Q.; Zhang, Y.; Montazerian, M.; Gulbiten, O.; Mauro, J. C.; Zanotto, E. D.; Yue, Y. Understanding Glass through Differential Scanning Calorimetry. Chem. Rev. 2019, 119, 7848– 7939,  DOI: 10.1021/ACS.CHEMREV.8B00510
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    Understanding Glass through Differential Scanning Calorimetry
    Zheng, Qiuju; Zhang, Yanfei; Montazerian, Maziar; Gulbiten, Ozgur; Mauro, John C.; Zanotto, Edgar D.; Yue, Yuanzheng
    Chemical Reviews (Washington, DC, United States) (2019), 119 (13), 7848-7939CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
    A review. Differential scanning calorimetry (DSC) is a powerful tool to address some of the most challenging issues in glass science and technol., such as the nonequil. nature of the glassy state and the detailed thermodn. and kinetics of glass-forming systems during glass transition, relaxation, rejuvenation, polyamorphic transition, and crystn. The utility of the DSC technique spans across all glass-forming chemistries, including oxide, chalcogenide, metallic, and org. systems, as well as recently discovered metal-org. framework glass-forming systems. Here we present a comprehensive review of the many applications of DSC in glass science with focus on glass transition, relaxation, polyamorphism, and crystn. phenomena. We also emphasize recent advances in DSC characterization technol., including flash DSC and temp.-modulated DSC. This review demonstrates how DSC studies have led to a multitude of relevant advances in the understanding of glass physics, chem., and even technol.
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    Kuczek, J.; Sułowska, J.; Lach, R.; Szumera, M. The Glass Formation and Crystallization Studies on Iron Phosphate–Silicate Glasses. J. Therm. Anal. Calorim. 2019, 138, 1953– 1964,  DOI: 10.1007/S10973-019-08523-Y/FIGURES/6
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    The glass formation and crystallization studies on iron phosphate-silicate glasses
    Kuczek, Justyna; Sulowska, Justyna; Lach, Radoslaw; Szumera, Magdalena
    Journal of Thermal Analysis and Calorimetry (2019), 138 (3), 1953-1964CODEN: JTACF7; ISSN:1388-6150. (Springer)
    The assessment of impact of incorporation of various amt. of Fe2O3 at the expense of MgO and CaO on the glassy phase formation and thermal stability exhibited in P2O5-SiO2-K2O-MgO-CaO-Fe2O3 system was carried out. The characteristic temps. for iron phosphate-silicate glasses and glass-cryst. materials were designated from assocd. DSC curves. Selected samples were subjected to the process of induced crystn., and products combined with particular exothermic effects were identified. Combination of DSC, XRD and SEM-EDS methods enabled to collect invaluable data concerning the course of crystn. of not only iron phosphate-silicate glasses subjected to the process of induced crystn., but also glass-cryst. materials obtained directly through melt-quenched technique. The amt. of particular cryst. products assocd. with selected devitrificates was detd. via Rietveld technique. Results of the conducted study indicated that Fe2O3 addn. conduces to the decrease in crystn. temps. and thermal stability which was reflected in calcd. values of ΔT and KW parameters. Concomitantly, glass with 20 mol% iron (III) oxide addn. exhibited significantly improved, distinctive thermal stability among the materials in the analyzed series. The performed study is a contribution to the knowledge of iron phosphate glasses family and assocd. glass-cryst. materials.
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    Lusvardi, G.; Malavasi, G.; Menabue, L.; Menziani, M. C. Synthesis, Characterization, and Molecular Dynamics Simulation Of Na2O–CaO–SiO2–ZnO Glasses. J. Phys. Chem. B 2002, 106, 9753– 9760,  DOI: 10.1021/JP020321S
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    Synthesis, Characterization, and Molecular Dynamics Simulation Of Na2O-CaO-SiO2-ZnO Glasses
    Lusvardi, G.; Malavasi, G.; Menabue, L.; Menziani, M. C.
    Journal of Physical Chemistry B (2002), 106 (38), 9753-9760CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
    The glass of compn. Na2O·CaO·2SiO2 was modified upon addn. of ZnO to obtain the series of glasses Na2O·CaO·2SiO2·xZnO (x = 0.17, 0.34, 0.68), where x = 0.68 is the exptl. detd. max. zinc content that does not produce phase sepn. The glasses were investigated by means of d. and thermal measurements (glass-transition and crystn. temps.); moreover, the phases sepd. upon crystn. were identified. The results of mol. dynamics (MD) simulations combined with the anal. of the crystal structure of the main phases sepd. (Na2Ca(SiO3)2 and Na2ZnSiO4) provided insights into the structural role of zinc and its effect on the short- and medium-range order of the glass structures.
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    Zheng, W.; Cao, H.; Zhong, J.; Qian, S.; Peng, Z.; Shen, C. CaO–MgO–Al2O3–SiO2 Glass-Ceramics from Lithium Porcelain Clay Tailings for New Building Materials. J. Non-Cryst. Solids 2015, 409, 27– 33,  DOI: 10.1016/J.JNONCRYSOL.2014.11.002
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    CaO-MgO-Al2O3-SiO2 glass-ceramics from lithium porcelain clay tailings for new building materials
    Zheng, Weihong; Cao, Hua; Zhong, Jingbo; Qian, Shaoyang; Peng, Zhigang; Shen, Chunhua
    Journal of Non-Crystalline Solids (2015), 409 (), 27-33CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
    Lithium porcelain clay tailings (contg. 1.2 wt.% Li2O) blended with other chem. raw materials were used to develop a new glass-ceramic of CaO-MgO-Al2O3-SiO2 system for rolling process. The effects of TiO2 and ZnO oxides on melting and crystn. behaviors of glasses were investigated by DTA, XRD, EPMA and viscosity test. The results showed that melting temp., forming temp. and glass transition temp. (Tg) of glasses were decreased with the increase of ZnO addn. Nevertheless, the crystn. temp. was shifted from 864 to 901 °C when the addn. of TiO2 decreased from 2 wt.% to 0.5 wt.%. Diopside as a major cryst. phase and spinel as a minor phase are pptd. in M3 specimen with 2.5 wt.% ZnO and 0.5 wt.% TiO2. The columnar and granular cryst. phases were distributed in M3 specimen nucleated at 750°C for 2 h and followed by crystn. at 1110°C for 2 h, which resulted in proper appearance suitable for decorative materials.
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    Grangeon, S.; Fernandez-Martinez, A.; Baronnet, A.; Marty, N.; Poulain, A.; Elkaïm, E.; Roosz, C.; Gaboreau, S.; Henocq, P.; Claret, F. Quantitative X-Ray Pair Distribution Function Analysis of Nanocrystalline Calcium Silicate Hydrates: A Contribution to the Understanding of Cement Chemistry. J. Appl. Crystallogr. 2017, 50, 14– 21,  DOI: 10.1107/S1600576716017404
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    Quantitative X-ray pair distribution function analysis of nanocrystalline calcium silicate hydrates: a contribution to the understanding of cement chemistry
    Grangeon, Sylvain; Fernandez-Martinez, Alejandro; Baronnet, Alain; Marty, Nicolas; Poulain, Agnieszka; Elkaim, Erik; Roosz, Cedric; Gaboreau, Stephane; Henocq, Pierre; Claret, Francis
    Journal of Applied Crystallography (2017), 50 (1), 14-21CODEN: JACGAR; ISSN:1600-5767. (International Union of Crystallography)
    A review. The structural evolution of nanocryst. calcium silicate hydrate (C-S-H) as a function of its calcium to silicon (Ca/Si) ratio has been probed using qual. and quant. X-ray at. pair distribution function anal. of synchrotron X-ray scattering data. Whatever the Ca/Si ratio, the C-S-H structure is similar to that of tobermorite. When the Ca/Si ratio increases from ∼0.6 to ∼1.2, Si wollastonite-like chains progressively depolymerize through preferential omission of Si bridging tetrahedra. When the Ca/Si ratio approaches ∼1.5, nanosheets of portlandite are detected in samples aged for 1 d, while microcryst. portlandite is detected in samples aged for 1 yr. High-resoln. transmission electron microscopy imaging shows that the tobermorite-like structure is maintained to Ca/Si > 3.
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    Luz, A. P.; Pandolfelli, V. C. Halting the Calcium Aluminate Cement Hydration Process. Ceram. Int. 2011, 37, 3789– 3793,  DOI: 10.1016/j.ceramint.2011.06.034
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    Halting the calcium aluminate cement hydration process
    Luz, A. P.; Pandolfelli, V. C.
    Ceramics International (2011), 37 (8), 3789-3793CODEN: CINNDH; ISSN:0272-8842. (Elsevier Ltd.)
    Ca aluminate cement reactions with H2O result in anhyd. phases dissoln., followed by nucleation and crystal growth of hydrate compds. Due to the dynamic characteristics of this process and to evaluate the phase transformation kinetics of such materials, suitable methods to halt hydration are required. The use of acetone and microwave drying, aiming to withdraw free H2O and inhibit further reactions, was evaluated. X-ray diffraction was used to quantify the phases generated in the cement samples kept at 37° for 1-15 days. The advantages and drawbacks of these procedures are presented and discussed. Using microwaves to halt the hydration process in shaped samples seems to be effective to withdraw the cement free H2O, if a previous grinding of the material is carried out. The procedure suggested can be used in researches in the refractory castable area, endodontic cements and others.
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    Christensen, A. N.; Fjellvåg, H.; Lehmann, M. S. Time Resolved Powder Neutron Diffraction Investigations of Reactions of Solids with Water. Cem. Concr. Res. 1986, 16, 871– 874,  DOI: 10.1016/0008-8846(86)90010-4
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    Malfait, W. J.; Xue, X. The Nature of Hydroxyl Groups in Aluminosilicate Glasses: Quantifying Si-OH and Al-OH Abundances along the SiO2-NaAlSiO4 Join by 1H, 27Al-1H and 29Si-1H NMR Spectroscopy. Geochim. Cosmochim. Acta 2010, 74, 719– 737,  DOI: 10.1016/j.gca.2009.10.036
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    The nature of hydroxyl groups in aluminosilicate glasses: Quantifying Si-OH and Al-OH abundances along the SiO2-NaAlSiO4 join by 1H, 27Al-1H and 29Si-1H NMR spectroscopy
    Malfait, Wim J.; Xue, Xianyu
    Geochimica et Cosmochimica Acta (2010), 74 (2), 719-737CODEN: GCACAK; ISSN:0016-7037. (Elsevier B.V.)
    The combined results of 27Al-1H and 1H-29Si-1H cross polarization NMR expts. for hydrous glasses (contg. 0.5-2 wt% water) along the SiO2-NaAlSiO4 join confirm that the dissoln. mechanism of water in aluminosilicate glasses is fundamentally the same as for Al-free systems, i.e. the dissolved water ruptures oxygen bridges and creates Si-OH and Al-OH groups, in addn. to forming mol. water (H2Omol). The fraction of Al-OH increases non-linearly as the Al content increases with up to half of the OH groups as Al-OH for compns. close to NaAlSiO4. The relative abundances of the different species are controlled by the degree of Al-avoidance and the relative tendency of hydrolysis of the different types of oxygen bridges, Si-O-Si, Si-O-Al and Al-O-Al. A set of homogeneous reactions is derived to model the measured Al-OH/Si-OH speciation, and the obtained equil. consts. are in agreement with literature data on the degree of Al-avoidance. With these equil. consts., the abundance of the different oxygen species, i.e. Si-O-Si, Si-O-Al, Al-O-Al, Si-OH, Al-OH and H2Omol, can be predicted for the entire range of water and Al contents.
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    Bauchy, M.; Qomi, M. J. A.; Ulm, F. J.; Pellenq, R. J.-M. Order and Disorder in Calcium-Silicate-Hydrate. J. Chem. Phys. 2014, 140, 214503,  DOI: 10.1063/1.4878656
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    Order and disorder in calcium-silicate-hydrate
    Bauchy, M.; Abdolhosseini Qomi, M. J.; Ulm, F.-J.; Pellenq, R. J.-M.
    Journal of Chemical Physics (2014), 140 (21), 214503/1-214503/9CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)
    Despite advances in the characterization and modeling of cement hydrates, the at. order in Ca-Silicate-Hydrate (C-S-H), the binding phase of cement, remains an open question. Indeed, in contrast to the former cryst. model, recent mol. models suggest that the nanoscale structure of C-S-H is amorphous. To elucidate this issue, the authors analyzed the structure of a realistic simulated model of C-S-H, and compared the latter to cryst. tobermorite, a natural analog of C-S-H, and to an artificial ideal glass. C-S-H appears as amorphous, when averaged on all atoms. However, an anal. of the order around each at. species reveals that its structure shows an intermediate degree of order, retaining some characteristics of the crystal while acquiring an overall glass-like disorder. Thanks to a detailed quantification of order and disorder, while C-S-H retains some signatures of a tobermorite-like layered structure, hydrated species are completely amorphous. (c) 2014 American Institute of Physics.
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    Gates-Rector, S.; Blanton, T. The Powder Diffraction File: A Quality Materials Characterization Database. Powder Diffr. 2019, 34, 352– 360,  DOI: 10.1017/S0885715619000812
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    The Powder Diffraction File: a quality materials characterization database
    Gates-Rector, Stacy; Blanton, Thomas
    Powder Diffraction (2019), 34 (4), 352-360CODEN: PODIE2; ISSN:0885-7156. (Cambridge University Press)
    The ICDD's Powder Diffraction File (PDF) is a database of inorg. and org. diffraction data used for phase identification and materials characterization by powder diffraction. The PDF has been available for over 75 years and finds application in X-ray, synchrotron, electron, and neutron diffraction analyses. With entries based on powder and single crystal data, the PDF is the only crystallog. database where every entry is editorially reviewed and marked with a quality mark that alerts the user to the reliability/quality of the submitted data. The editorial processes of ICDD's quality management system are unique in that they are ISO 9001:2015 certified. Initially offered as text on paper cards and books, the PDF evolved to a computer-readable database in the 1960s and today is both computer and web accessible. With data mining and phase identification software available in PDF products, and the databases' compatibility with vendor (third party) software, the 1 000 000+ published PDF entries serve a wide range of disciplines covering academic, industrial, and government labs. Details describing the content of database entries are presented to enhance the use of the PDF.
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    Egami, T.; Billinge, S. J. L. Underneath the Bragg Peaks: Structural Analysis of Complex Materials; Elsevier, 2003.
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    Petkov, V.; Billinge, S. J. L.; Shastri, S. D.; Himmel, B. High-Resolution Atomic Distribution Functions of Disordered Materials by High-Energy X-Ray Diffraction. J. Non-Cryst. Solids 2001, 293-295, 726– 730,  DOI: 10.1016/S0022-3093(01)00864-X
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    High-resolution atomic distribution functions of disordered materials by high-energy x-ray diffraction
    Petkov, V.; Billinge, S. J. L.; Shastri, S. D.; Himmel, B.
    Journal of Non-Crystalline Solids (2001), 293-295 (), 726-730CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier Science B.V.)
    The at.-scale structure of materials with different degrees of structural disorder has been investigated by high-energy (E ≥60 keV) X-ray diffraction. Good quality structure functions extended to wave vectors of magnitude Q ≥40 Å-1 have been obtained even in case of materials composed of weakly scattering, light at. species. The corresponding high-resoln. at. distribution functions allowed fine structural features differing in as little as (0.14 Å) to be resolved. In particular, the distinct Ga-As (∼2.43 Å) and In-As (2.61 Å) bonds in In-Ga-As alloys have been differentiated. The at.-scale structure of 'restacked' WS2 has been detd. and the presence of three distinct W-W distances occurring at 2.77, 3.27 and 3.85 Å established. Finally, Si-O (∼1.61 Å), Al-O (∼1.75 Å) and Ca-O (∼2.34 Å) bonds in calcium aluminosilicate glasses have been differentiated and the characteristics of the resp. co-ordination polyhedra revealed.
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    Gedekar, K. A.; Wankhede, S. P.; Moharil, S. V.; Belekar, R. M. Synthesis, Crystal Structure and Luminescence in Ca3Al2O6. J. Mater. Sci.: Mater. Electron. 2018, 29, 6260– 6265,  DOI: 10.1007/s10854-018-8603-5
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    Synthesis, crystal structure and luminescence in Ca3Al2O6
    Gedekar, K. A.; Wankhede, S. P.; Moharil, S. V.; Belekar, R. M.
    Journal of Materials Science: Materials in Electronics (2018), 29 (8), 6260-6265CODEN: JSMEEV; ISSN:0957-4522. (Springer)
    Bluish green emitting phosphor, Ca3Al2O6:Ce3+, is prepd. by low-temp. combustion method. X-ray diffraction, photoluminescence, SEM techniques are used to characterize the synthesized phosphor. The most efficient bluish green (483 nm) emission is obsd. under the excitation by near UV light. The emission characteristics are credited to 5d → 4f type transitions in Ce3+. The luminescence properties of Eu2+ are predicted for the first time from those of Ce3+. Also, photoluminescence of Eu3+ is studied in the same host. The emission spectrum of Ca3Al2O6:Eu3+ shows the peak at 592 (orange) and 614 nm (red) wavelengths. Ca3Al2O6:Ce3+phosphor can be a potential blue phosphor for field emission display, solid-state lighting and LED.
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    Huang, X. H.; Liao, J. L.; Zheng, K.; Hu, H. H.; Wang, F. M.; Zhang, Z. T. Effect of B2O3 Addition on Viscosity of Mould Slag Containing Low Silica Content. Ironmaking Steelmaking 2014, 41, 67– 74,  DOI: 10.1179/1743281213Y.0000000107
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    Effect of B2O3 addition on viscosity of mould slag containing low silica content
    Huang, X. H.; Liao, J. L.; Zheng, K.; Hu, H. H.; Wang, F. M.; Zhang, Z. T.
    Ironmaking & Steelmaking (2014), 41 (1), 67-74CODEN: IMKSB7; ISSN:0301-9233. (Maney Publishing)
    The viscosity of SiO2-30Al2O3-B2O3-12Na2O-CaO slag system (CaO/SiO2 = 2·68-7·35, B2O3 = 0-9 wt-%) was investigated in the present study. The objective is to study the influence of B2O3 on the viscosity and structure of mold slags contg. low silica content. The research of the low silica slag system is meaningful because of it is less reactive with Al during continuous casting of steels contg. high amts. of dissolved aluminum, such as transformation induced plasticity assisted steels. The viscosities of these quinternary slags decreased slightly with an increase in the content of additive B2O3 above the break temp. The apparent activation energy of viscous flow was found to decrease with increasing B2O3 content. The break temp. also decreased with increasing B2O3 content. Based on the exptl. data, the decrease in break temp. per mol.-% B2O3 ΔTbr is 15·23 K. An empirical model was then established to predict the break temp. of mold slags contg. B2O3, and the deviation is between -25 and +25 K. Based on the viscosity and Fourier transform IR anal., it is proposed that the three-coordinated boron is dominated in these slags over the entire compositional range, and the borosilicate networks are loosened with increasing B2O3 content in the present study. The Riboud model was modified empirically based on the present exptl. data, and the mean deviation is ∼13%.
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    Bi, Z.; Li, K.; Jiang, C.; Zhang, J.; Ma, S.; Sun, M.; Wang, Z.; Li, H. Effects of B2O3 on the Structure and Properties of Blast Furnace Slag by Molecular Dynamics Simulation. J. Non-Cryst. Solids 2021, 551, 120412,  DOI: 10.1016/J.JNONCRYSOL.2020.120412
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    Effects of B2O3 on the structure and properties of blast furnace slag by molecular dynamics simulation
    Bi, Zhisheng; Li, Kejiang; Jiang, Chunhe; Zhang, Jianliang; Ma, Shufang; Sun, Minmin; Wang, Ziming; Li, Hongtao
    Journal of Non-Crystalline Solids (2021), 551 (), 120412CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
    B2O3 has the advantages of reducing the liquidus temp. and enhancing the fluidity of slag, while its influence mechanism in at. scale has not yet been fully understood. Mol. dynamics simulation was conducted to investigate the influence of B2O3 on the structure and properties of SiO2-CaO-Al2O3-B2O3 blast furnace slag system at 1773 K. Results showed that a large no. of [SiO4]4--[BO3]3- structures are generated in the system after B2O3 added, Si4+ ions mainly exist in the form of [SiO4]4- tetrahedrons and B3+ ions mainly exist in the form of [BO3]3- planar triangular structures and [BO4]5- tetrahedrons. With the increase of B2O3 content, the proportion of [BO3]3- planar triangular structures increase. In addn., the content of bridge oxygen in the microstructure of slag increases obviously, the content of non-bridge oxygen decreases, and the polymn. degree of the system increases somewhat. Through the anal. of microscopic mechanism and the modified NPL viscosity model, combined with exptl. data, the truth that the slag viscosity decreases with the increase of B2O3 contents were known in the simulated concn. range.
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    Yadav, A. K.; Singh, P. A Review of the Structures of Oxide Glasses by Raman Spectroscopy. RSC Adv. 2015, 5, 67583– 67609,  DOI: 10.1039/C5RA13043C
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    A review of the structures of oxide glasses by Raman spectroscopy
    Yadav, Avadhesh Kumar; Singh, Prabhakar
    RSC Advances (2015), 5 (83), 67583-67609CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)
    The family of oxide glasses is very wide and it is continuously developing. The rapid development of advanced and innovative glasses is under progress. Oxide glasses have a variety of applications in articles for daily use as well as in advanced technol. fields such as X-ray protection, fiber glasses, optical instruments and lab glassware. Oxide glasses basically consist of network formers, such as borate, silicate, phosphate, borosilicate, borophosphate, and network modifiers such as alkali, alk. earth and transition metals. In the present review article, Raman spectroscopy results for the structures of borate, silicate, phosphate, borosilicate, borophosphate, aluminosilicate, phosphosilicate, alumino-borosilicate and tellurite glasses are summarized.
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    Aguiar, H.; Serra, J.; González, P.; León, B. Structural Study of Sol–Gel Silicate Glasses by IR and Raman Spectroscopies. J. Non-Cryst. Solids 2009, 355, 475– 480,  DOI: 10.1016/J.JNONCRYSOL.2009.01.010
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    Structural study of sol-gel silicate glasses by IR and Raman spectroscopies
    Aguiar, H.; Serra, J.; Gonzalez, P.; Leon, B.
    Journal of Non-Crystalline Solids (2009), 355 (8), 475-480CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
    A study of the structure and bonding configuration of sol-gel silicate glasses by Raman and IR spectroscopies is presented. Moreover, a review of the Raman lines and IR bands assignment, the identification of the non-bridging silicon-oxygen groups and the ring structures are also demonstrated. The evolution of the changes of the bonding configuration in the compn. and the stabilization temp. of the bioactive glasses is discussed in terms of the structural and textural characteristics of the glasses. Raman and IR analyses contribute to the improvement in understanding of the local symmetry for sol-gel silicate glasses. IR spectroscopy has allowed to identify the vibration bands of the hydroxyl groups assocd. with various configurations of the terminal silanol bonds on the glass surface and the free mol. water in the glass matrix. Raman anal. has provided an alternative method of quantifying the network connectivity grade and predicting the textural properties of the sol-gel silicate glasses.
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    Li, H.; Hrma, P.; Vienna, J. D.; Qian, M.; Su, Y.; Smith, D. E. Effects of Al2O3, B2O3, Na2O, and SiO2 on Nepheline Formation in Borosilicate Glasses: Chemical and Physical Correlations. J. Non-Cryst. Solids 2003, 331, 202– 216,  DOI: 10.1016/j.jnoncrysol.2003.08.082
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    Effects of Al2O3, B2O3, Na2O, and SiO2 on nepheline formation in borosilicate glasses: chemical and physical correlations
    Li, Hong; Hrma, Pavel; Vienna, John D.; Qian, Maoxu; Su, Yali; Smith, Donald E.
    Journal of Non-Crystalline Solids (2003), 331 (1-3), 202-216CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier Science B.V.)
    Raman spectroscopy was applied to complex sodium aluminoborosilicate glasses that ppt. nepheline as their primary phase. The main focus was on the Raman band at 850 cm-1 (wavenumber) obsd. in quenched glasses. Based on the literature, the 850 cm-1 band was assigned to AlIV-O-Si units in which tetrahedral AlIV are substituted for Si in the network, creating [AlO4/2]- anions that are charge-balanced by Na+ cations. The same glasses with various temp. histories were examd. with optical microscopy, SEM and TEM. The results indicated that the 850 cm-1 Raman band was assocd. with nanocrystals that formed in the melts and were preserved in the quenched samples. The chem. of these nanocrystals resembled nepheline. Models relating the intensity of the Raman band at 850 cm-1 and the liquidus temp. (TL) to glass compn. revealed that a relationship exists between these two properties. An increase in B2O3 and SiO2 decreased the Raman band intensity and the TL, whereas an increase in Al2O3 and Na2O increased both properties. These effects were attributed to the influence of various oxides on the Na+-[AlO4/2]- activity in the melt.
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    Kim, G. H.; Sohn, I. Role of B2O3 on the Viscosity and Structure in the CaO-Al2O3-Na2O-Based System. Metall. Mater. Trans. B 2014, 45, 86– 95,  DOI: 10.1007/s11663-013-9953-2
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    Role of B2O3 on the Viscosity and Structure in the CaO-Al2O3-Na2O-Based System
    Kim, Gi Hyun; Sohn, Il
    Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science (2014), 45 (1), 86-95CODEN: MTBSEO; ISSN:1073-5615. (Springer)
    The effect of B2O3 on the viscosity and structure in the calcium-aluminate melt flux system contg. Na2O was studied. An increase in the B2O3 content at fixed CaO/Al2O3 ratio lowered the viscosity. Higher CaO/Al2O3 ratio at fixed B2O3 content also decreased the viscosity. The alumino-borate structures were confirmed through Fourier transformed IR (FTIR) and Raman spectroscopy and consisted of [AlO4]-tetrahedral structural units, [BO3]-triangular structural units, and [BO4]-tetrahedral structural units, which could be correlated to the viscosity. At fixed CaO/Al2O3 ratio, B2O3 addns. decreased the [AlO4]-tetrahedral structural units and transformed the 3-D network structures such as pentaborate and tetraborate into 2-D network structures of boroxol and boroxyl rings by breaking the bridged oxygen atoms (O0) to produce non-bridged oxygen atoms (O-) leading to a decrease in the molten flux viscosity. At fixed B2O3 contents and higher CaO/Al2O3 ratio, 3-D complex network structures become 3-D simple and 2-D isolated network structures, resulting in lower viscosities. The apparent activation energy for viscous flow varied from 132 to 249 kJ/mol according to the compn. of B2O3 and CaO/Al2O3 ratio.
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    Torréns-Martín, D.; Fernández-Carrasco, L.; Martínez-Ramírez, S.; Ibáñez, J.; Artús, L.; Matschei, T. Raman Spectroscopy of Anhydrous and Hydrated Calcium Aluminates and Sulfoaluminates. J. Am. Ceram. Soc. 2013, 96, 3589– 3595,  DOI: 10.1111/JACE.12535
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    Raman Spectroscopy of Anhydrous and Hydrated Calcium Aluminates and Sulfoaluminates
    Torrens-Martin, David; Fernandez-Carrasco, Lucia; Martinez-Ramirez, Sagrario; Ibanez, Jordi; Artus, Lluis; Matschei, Thomas
    Journal of the American Ceramic Society (2013), 96 (11), 3589-3595CODEN: JACTAW; ISSN:0002-7820. (Wiley-Blackwell)
    Recent investigations have revealed the great potential of Raman spectroscopy for the characterization of clinker minerals and com. portland cements. The usefulness of this technique for the identification of anhyd., hydrated, and carbonated phases in cement-based materials has been demonstrated. In the present work, the application of micro-Raman spectroscopy for the characterization of the main clinker phases of calcium aluminate cements and calcium sulfoaluminate cement is explored. The main stable hydrated phases as well as several important carbonated phases are investigated. Raman measurements on the following phases are reported: (i) pure, unhydrated phases: CA, C12A7, CA2, C2AS, cubic C3A, C4AF, and C4A3; (ii) hydrated phases: ettringite, monosulfoaluminate, and hydrogarnet (C3AH6); (iii) carboaluminate phases: hemicarboaluminate and monocarboaluminate. The present results, which are discussed in terms of the internal vibrational modes of the aluminate, carbonate, and sulfate mol. groups as well as stretching O-H vibrations, show the ability of Raman spectroscopy to identify the main hydrated and unhydrated phases in the aluminate and sulfoaluminate cements. The Raman spectra obtained in this work provide an extended database to the existing data published in the literature.
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    Licheron, M.; Montouillout, V.; Millot, F.; Neuville, D. R. Raman and 27Al NMR Structure Investigations of Aluminate Glasses: (1 - X)Al2O3 - x MO, with M = Ca, Sr, Ba and 0.5 < x < 0.75. J. Non-Cryst. Solids 2011, 357, 2796– 2801,  DOI: 10.1016/j.jnoncrysol.2011.03.001
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    Raman and 27Al NMR structure investigations of aluminate glasses: (1-x)Al2O3-xMO, with M = Ca, Sr, Ba and 0.5< x< 0.75)
    Licheron, Marina; Montouillout, Valerie; Millot, Francis; Neuville, Daniel R.
    Journal of Non-Crystalline Solids (2011), 357 (15), 2796-2801CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
    Aluminate glasses are important materials from a fundamental structural point of view because Al is the only network former. They present also a technol. interest because of their good IR transmission and ultralow optical losses. Aluminum in glasses of the system MO-Al2O3 (M = Ca, Sr, Ba) can have different coordination nos., essentially 4 and 6, as a function of the MO/Al2O3 ratio. Using Raman spectroscopy and high field 27Al NMR spectroscopy, we have detd. the structure of aluminum network as a function of MO/Al2O3 ratio with M corresponds to different alk.-earth cations. Al is essentially in 4-fold coordination with different amts. for Al2O3 between 50 and 75% but varies between Q2 and Q4 species as a function of MO/Al2O3 ratio where Q is tetrahedral species and n the no. of bridging oxygen.
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    Martínez-Ramírez, S.; Gutierrez-Contreras, R.; Husillos-Rodriguez, N.; Fernández-Carrasco, L. In-Situ Reaction of the Very Early Hydration of C3A-Gypsum-Sucrose System by Micro-Raman Spectroscopy. Cem. Concr. Compos. 2016, 73, 251– 256,  DOI: 10.1016/j.cemconcomp.2016.07.020
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    In-situ reaction of the very early hydration of C3A-gypsum-sucrose system by Micro-Raman spectroscopy
    Martinez-Ramirez, Sagrario; Gutierrez-Contreras, Rocio; Husillos-Rodriguez, Nuria; Fernandez-Carrasco, Lucia
    Cement & Concrete Composites (2016), 73 (), 251-256CODEN: CCOCEG; ISSN:0958-9465. (Elsevier Ltd.)
    This paper studied in situ, by Micro-Raman spectroscopy, the very early hydration of C3A in the presence and absence of sulfates and with sucrose as an additive. For C3A hydration in the absence of gypsum, when carbonation is not avoided, carbonate-AFm phases are formed, but in the presence of gypsum, hydroxi-AFm are the main phases. Ettringite is the AFm stable phase developed initially at 70 min of hydration with gypsum and no monosulfate is formed. In the presence of sucrose, this salt, instead of sulfate, is adsorbed over the surface of the C3A, avoiding its reaction with sulfates until sucrose desorption. Three hours are necessary to lead to ettringite formation. A nucleation poisoning/adsorption surface mechanism is proposed for added sucrose systems.
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    You, J.-L.; Jiang, G.-C.; Hou, H.-Y.; Chen, H.; Wu, Y.-Q.; Xu, K.-D. Quantum Chemistry Study on Superstructure and Raman Spectra of Binary Sodium Silicates. J. Raman Spectrosc. 2005, 36, 237– 249,  DOI: 10.1002/jrs.1287
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    Quantum chemistry study on superstructure and Raman spectra of binary sodium silicates
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    Journal of Raman Spectroscopy (2005), 36 (3), 237-249CODEN: JRSPAF; ISSN:0377-0486. (John Wiley & Sons Ltd.)
    Raman spectra of binary sodium silicates in various components were calcd. by the SCF MO ab initio calcn. quantum chem. (QC) method with several polysilicon-oxygen tetrahedral model clusters with both 6-31G and 6-31G(d) basis sets being applied. Relevant pure anion clusters were also be calcd. to det. the cation effect by comparison with the available sodium series. High and intermediate Raman-active wavenumber ranges were esp. considered. The sym. stretching vibrational wavenumber of non-bridging oxygen (NBO) in the high-wavenumber range and its Raman scattering cross-section were deduced and analyzed. Several synthesized binary sodium silicate crystals were measured for comparison. The correlation between the vibrational Raman shift and the microscopic environment of the silicon-oxygen tetrahedron (SiOT) was found based on interior stress of configuration or superstructure, which depends on the connecting topol. of adjacent SiOTs. A newly established empirical stress index of a tetrahedron (SIT) was introduced to elucidate the above relationship. A new notation of SiOT accompanied by superstructure information was proposed and used to describe the practical and delicate types of SiOT in various states of binary sodium silicates. The Raman scattering cross-section of the sym. stretching vibration of NBO shows a roughly decreasing relationship with SIT or the Raman shift in the high-wavenumber range only under the circumstance of equiv. linkage between SiOTs, and Raman optical activity (ROA) enhancement of Q3 species occurs with Q4 species as its nearest neighbor, which indicates the electronic coupling between them. It was also demonstrated that the Si-Ob-Si bending vibrational Raman shift in the intermediate wavenumber range shows a monotonic decreasing relationship with the value of the Si-Ob-Si angle while other minor impacting factors remains unknown. This work offers basic information on the superstructure of binary sodium silicates and its relationship with characteristic vibrational Raman spectra, which can be widely applied in qual. and quant. studies of the microstructure of silicates.
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    Effect of Li2SO4 on the structure of Li2O-B2O3 glasses
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    IR reflectance and Raman spectroscopic measurements of xLi2SO4·(1-x)[RLi2O·B2O3] fast ionic conducting glass samples with R = 1 (metaborate), R = 2 (pyroborate) and 0≤x≤0.60 have been made. The SO42- ions of slightly distorted Td symmetry are found to occupy interstitial positions in the glass network and to decrease the basicity of the Li+-hosting sites. Increasing Li2SO4 content induces small structural changes to the depolymd. R = 2 glasses, but has a larger effect on the structure of the more covalently bonded R = 1 network. In this latter case, small addns. of Li2SO4, up to x≈0.05, induce the transformation of metaborate triangles into their isomeric tetrahedral species. Further increases of x lead to the reversal of this trend. The complex influence of Li2SO4 on the metaborate network is obsd. in the irregular shape of the Li2SO4-Li2O-B2O3 glass-forming range, as well as on the non-monotonic dependence of the activation energy for ion transport on x. The spectroscopic results are compatible with the formation of Li2SO4 microdomains at large Li2SO4 contents.
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    Black, L.; Breen, C.; Yarwood, J.; Deng, C. S.; Phipps, J.; Maitland, G. Hydration of Tricalcium Aluminate (C3A) in the Presence and Absence of Gypsum - Studied by Raman Spectroscopy and X-Ray Diffraction. J. Mater. Chem. 2006, 16, 1263– 1272,  DOI: 10.1039/b509904h
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    Hydration of tricalcium aluminate (C3A) in the presence and absence of gypsum-studied by Raman spectroscopy and X-ray diffraction
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    Journal of Materials Chemistry (2006), 16 (13), 1263-1272CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)
    Raman spectroscopy has been used to follow the hydration of one of the principal components of Ordinary Portland Cement (OPC) clinkers, tricalcium aluminate, both in the absence and in the presence of calcium sulfate. Direct in-situ anal. of the hydrating paste surface was possible. Spectra were recorded regularly during the first 24 h of hydration, and then systematically after hydration periods of up to 28 days. X-Ray diffraction was performed to confirm sample identity, firstly after 24 h and then regularly in coordination with Raman anal. Hydration in the absence of sulfate was rapid and led to the initial formation of C4AH19 and subsequently C3AH6. Characteristic changes were seen in the Raman spectra and the products' identities confirmed by XRD. Hydration in the presence of sulfate led to very rapid ettringite (AFt) formation, with the first evidence of ettringite formation within 3 min. Ettringite gradually converted to monosulfate (AFm), with the re-formation of traces of gypsum at high sulfate contents. Ettringite was formed at the expense of C4AH19. The level of C4AH19 formed diminished greatly with increasing sulfate content. Care was taken throughout the study to exclude carbon dioxide, thus minimizing formation of various carbonate species, which could also be readily distinguished by Raman spectroscopy. By combining the results obtained using the well-established technique of X-ray diffraction with Raman spectroscopy, in-situ characterization of hydrating pastes has been achieved in real-time. In addn. to demonstrating the suitability of Raman spectroscopy for anal. of these systems this study should aid the understanding of tricalcium aluminate hydration and the formation of ettringite and monosulfate.
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    The temp. dependence of Li ions behavior of γ-LiAlO2 has been studied from 78 to 873 K. On heating, the Li ions underwent positional disordering along the structural channels, with the Li ions related modes at 220, 366 and 400 cm-1 broadening and weakening dramatically. An anomalous max. in the bandwidths of the Li ions related modes is obsd. It should be apparent that there are at least two distinct thermally activated processes. A model suggested by Andrade and Porto is used to describe the linewidth of a phonon.
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    Remy, C.; Reynard, B.; Madon, M. Raman Spectroscopic Investigations of Dicalcium Silicate: Polymorphs and High-Temperature Phase Transformations. J. Am. Ceram. Soc. 1997, 80, 413– 423,  DOI: 10.1111/j.1151-2916.1997.tb02846.x
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    Raman spectroscopic investigations of dicalcium silicate: polymorphs and high-temperature phase transformations
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    Polymorphs and high-temp. phase transformations of dicalcium silicate (Ca2SiO4) are investigated on powd. samples, using Raman scattering techniques. Raman spectra at room conditions of pure γ- and β-Ca2SiO4 and stabilized β- α'L- and α-Ca2SiO4 are presented in the frequency range of 110-1100 cm-1. Each polymorph can be identified by its Raman spectrum, even though strong similarities exist between the β, α'L, and α phases. In-situ high-temp. Raman spectroscopic studies in the temp. range of 298-1433 K on heating and cooling also are reported, started from γ-Ca2SiO4. Modifications occurring in the Raman spectra recorded in the wavenumber. range of 90-1000 cm-1 show up during heating, the irreversible γ → α'L phase transformation. Coexistence of γ and α'L grains is obsd. in the temp. range of 1091-1119 K at least. The differences obsd. between the γ-Ca2SiO4 and α'L-Ca2SiO4 Raman spectra suggest that this phase transformation is a reconstructive first-order transition. The reversible α'L ↹ β phase transformation also is described. Raman spectra of pure β and α'L phases resemble each other. The transition occurs from 949 K, on cooling, to 960-988 K, on heating, with a hysteresis probably dependent on the thermal history of the starting product. From the Raman scattering observations, this phase transformation also is considered as a first-order transformation and is probably of a displacive type.
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    A procedure for deconvolution of complex Raman spectra of amorphous materials (e.g. silicate glass and melt) is described. The line shapes and quality of the fits are detd. statistically after correction for the temp.- and frequency-dependence of the Raman intensities. In the fitting routine, intensity, half-width, and position (frequency) of all bands are treated simultaneously as unconstrained variables. The no. of lines fitted to a spectrum is also treated statistically by numerical minimization of the squares of the deviations between the obsd. and the calcd. Raman envelopes and by maximizing the randomness of the residuals. It is assumed, however, that all bands are sym.
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    Kang, J.; Wang, J.; Zhou, X.; Yuan, J.; Hou, Y.; Qian, S.; Li, S.; Yue, Y. Effects of Alkali Metal Oxides on Crystallization Behavior and Acid Corrosion Resistance of Cordierite-Based Glass-Ceramics. J. Non-Cryst. Solids 2018, 481, 184– 190,  DOI: 10.1016/j.jnoncrysol.2017.10.048
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    Effects of alkali metal oxides on crystallization behavior and acid corrosion resistance of cordierite-based glass-ceramics
    Kang, Junfeng; Wang, Jing; Zhou, Xinyan; Yuan, Jian; Hou, Yansheng; Qian, Shaoyang; Li, Sheng; Yue, Yunlong
    Journal of Non-Crystalline Solids (2018), 481 (), 184-190CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
    MgO-Al2O3-SiO2-TiO2 glass-ceramics with 3 mol% alkali metal oxides were prepd., and the 3 mol% alkali metal oxides were induced by 3 mol% Na2O only, 1.5 mol% Na2O + 1.5 mol% Li2O, and 1.5 mol% Na2O + 1.5 mol% K2O, resp. Effects of alkali metal oxides on the crystn. behavior and acid corrosion resistance of the MgO-Al2O3-SiO2-TiO2 glass-ceramics were investigated. μ-Cordierite pptd. in the glass matrix firstly, and it changed into α-cordierite with the crystn. temp. increasing. Using K2O substitution of Na2O hindered the pptn. of cordierite, while the addn. of Li2O promoted the pptn. of μ-cordierite at low temps. When the main cryst. phase was μ-cordierite, the acid resistance of the glass-ceramics was significantly improved compared with the base glass. With the main cryst. phase changing from μ-cordierite to α-cordierite, the acid resistance of the glass-ceramics became worse, which was related to the honeycomb structure of α-cordierite. When 1.5 mol% Na2O was replaced by Li2O, the glass samples crystd. at 880° showed the optimum acid resistance with the min. wt. loss ∼0.096%.
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  1. Huan Zhang, Yaqi Zhang, Pengfei Yu, Li-Min Wang, Gong Li. Thermal analysis and non-isothermal crystallization kinetics of Ag–Ga2Te3–SnTe telluride glasses. Journal of Materials Research and Technology 2023, 24 , 759-768. https://doi.org/10.1016/j.jmrt.2023.03.050
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  • Abstract

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    Figure 1

    Figure 1. Schematic temperature regime for in situ measurements. The circles highlight the temperatures where the HE-SXRD patterns were collected, while the cubes represent the temperatures where both the HE-SXRD and PDF spectra were collected.

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    Figure 2

    Figure 2. DSC and TG curves of the investigated mold flux glass powder (heating rate: 20 °C/min).

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    Figure 3

    Figure 3. (a) Integrated 1D HE-SXRD profiles acquired during the in situ heating experiment at different temperatures; (b) magnified view of the 1D HE-SXRD profiles, in which the dash lines highlight the positions of the most substantial diffraction peak of crystalline phases. The patterns were indexed by referring to the ICDD PDF4+ database. (40)

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    Figure 4. Weight fraction of phases as a function of temperature, estimated by quantitative analysis of HE-SXRD patterns.

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    Figure 5

    Figure 5. In situ PDF data for a sample showing possible distributions of all atom–atom distances at selected temperatures. (a) r range from 1 to 20 Å and (b) r range from 1 to 5 Å.

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    Figure 6

    Figure 6. In situ high-temperature Raman spectra for the powder flux at different temperatures.

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    Figure 7

    Figure 7. Deconvolution of in situ high-temperature Raman spectra for the powder flux at (a) 400 °C, (b) 600 °C, (c) 700 °C, (d) 800 °C, and (e) RTc after cooling down.

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    This article references 59 other publications.

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      To support commercialization of the MgO-Al2O3-B2O-SiO2-based low-dielec. glass fibers, crystn. characteristics of the relevant glasses was investigated under various heat-treatment conditions. The study focused on the effects of iron on the related thermal properties and crystn. kinetics. Both air-cooled and nucleation-treated samples were characterized by using the DTA/differential scanning calorimeter method between room temp. and 1200°C. A collected set of properties covers glass transition temp. (Tg), max. crystn. temp. (Tp), sp. heat (ΔCp), enthalpy of crystn. (ΔHcryst), and thermal stability (ΔT = Tp-Tg). Using the Kinssiger method, the activation energy of crystn. was detd. Cryst. phases in the samples having various thermal histories were detd. using powder X-ray diffraction (XRD) and/or in situ high-temp. XRD method. Selective scanning electron microscope/energy-dispersive spectroscopy anal. provided evidence that crystal d. in the glass is affected by the iron concn. Glass network structures, for air-cooled and heat-treated samples, were examd. using a midinfrared spectroscopic method. Combining all of the results from our study, iron in glass is believed to function as a nucleation agent enhancing crystal population d. in the melt without altering a primary phase field. By comparing the XRD data of the glasses in two forms (bulk vs. powder), the following conclusions can be reached. The low-dielec. glass melt in com. operation should be resistant to crystn. above 1100°C. Microscopic amorphous phase sepn., possibly a borate-enriched phase sepg. from the silicate-enriched continuous phase can occur only if the melt is held at temps. below 1100°C, i.e., below the glass immiscibility temp. The study concludes that neither crystn. nor amorphous phase sepn. will be expected for drawing fibers between 1200°C and 1300°C in a com. operation.
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      To assess the effect of metallic particles (MPs) on heat transfer in glassy mold flux, a structurally stable glassy mold flux system composed of CaO-Al2O3-CaF2 was examd. with 0, 2, or 5 wt% of FeO or Fe MPs. The change of extinction coeff. by Mie Scattering of the Fe particles and absorption by FeO was quantified using Fourier transformation IR ray spectroscopy and an UV/Visible spectrometry. Thermal cond. of mold flux film with dispersed MPs was quantified using laser flash technique. One-dimensional Debye temp. was calcd., and particle morphol. and size distribution were obsd. using image anal. to explain variations in thermal cond. among the glass samples. Finally, to simulate the heat transfer ratio by both the conduction and radiation, the actual heat flux through mold flux film was measured using an IR Emitter Technique. The overall heat transfer rate across liq. flux film could be reduced significantly by a dispersion of MPs.
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      In continuous casting of steel, mold fluxes are used to prevent surface defects, such as longitudinal cracks. The crystn. of mold flux promotes mild cooling of the steel shell, but crystn. behavior has been still uncertain. Therefore, this study has been carried out to analyze the crystn. processes of mold flux. Mold flux used in this study has high tendency for crystn. Quenched specimens were heat-treated in various conditions and characterized. Glassy specimen heat-treated in the elec. furnace over 550°C for 180 min crystd. These cryst. were confirmed to be cuspidine by XRD anal. The no. of grains decreased and the av. grain size increased with rise of temp. of heat treatment. The growth velocity also increased with rise of temp. In-situ observation by the laser microscope revealed that the glassy specimen crystd. in a moment over 600°C and the surface of the specimen turned to be rough. This may lead to mild cooling in the mold.
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      Banijamali, S.; Rezaei, H. R.; Eftekhari Yekta, B.; Marghussian, V. K. Sinterability, Crystallization and Properties of Glass-Ceramic Tiles Belonging to CaF2-CaO-MgO-Al2O3-SiO2 System. Ceram. Int. 2007, 33, 1557– 1561,  DOI: 10.1016/j.ceramint.2006.06.004
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      Li, J. L.; Shu, Q. F.; Chou, K.
      Ironmaking & Steelmaking (2015), 42 (2), 154-160CODEN: IMKSB7; ISSN:0301-9233. (Maney Publishing)
      Recently, high Al steel has received increasing attention due to the perfect combination of strength to wt. ratio and excellent ductility. The high amt. of Al in the steel may cause great change on the chem. compns. of mold fluxes due to chem. reactions between SiO2 in the mold fluxes and Al in the steel, thereby influencing the phys. properties of the mold fluxes. Although many researches have reported on the effect of Al2O3/SiO2 mass ratio [w(Al2O3)/w(SiO2)] on the viscosity of mold fluxes, there is still a lot of controversies. In this work, the effect of w(Al2O3)/w(SiO2), which is in a large range of 0·22-1·75, on the viscosity of CaO-Al2O3-SiO2-CaF2 system as a base system for mold fluxes was investigated by the rotating cylinder method. The results showed that the viscosity of CaO-Al2O3-SiO2-CaF2 system first decreases and then increases as w(Al2O3)/w(SiO2) increases from 0·22 to 1·75. The viscosity values of CaO-Al2O3-SiO2-CaF2 system were also calcd. by employing various viscosity models. Comparisons between calcd. viscosity values and exptl. data have shown that values calcd. by Factsage and modified Riboud model were more close to the exptl. values than other models and values calcd. by the Riboud model and Shu model were much smaller than the exptl. values. X-ray diffraction (XRD) analyses on the samples after the viscosity measurement indicate that there were two kinds of cryst. phase, CaF2 and gehlenite (Ca2Al2SiO7) in all fluxes and gehlenite increases with increase of w(Al2O3)/w(SiO2).
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    10. 10
      Mukherjee, D. P.; Das, S. K. SiO2–Al2O3–CaO Glass-Ceramics: Effects of CaF2 on Crystallization, Microstructure and Properties. Ceram. Int. 2013, 39, 571– 578,  DOI: 10.1016/J.CERAMINT.2012.06.066
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      10
      SiO2-Al2O3-CaO glass-ceramics: Effects of CaF2 on crystallization, microstructure and properties
      Mukherjee, Debasis Pradip; Das, Sudip Kumar
      Ceramics International (2013), 39 (1), 571-578CODEN: CINNDH; ISSN:0272-8842. (Elsevier Ltd.)
      The effects of fluorine content on the nucleation and crystn. behavior of SiO2-Al2O3-CaO glass ceramics system have been investigated. The cryst. phases were detd. by X-ray diffraction (XRD). The crystn. kinetics was detd. by DTA (DTA). The microstructures were examd. by using scanning electron microscope (SEM). Fourier transformed IR spectra (FTIR) anal. was used to study the glass structure. The results showed that by increasing the fluorine content, both the crystn. peak temp. (Tp) and activation energy (E) decreased. Wollastonite, anorthite and gehlenite are the main cryst. phases that exist in the glass ceramics system. The study shows that fluorine promoted initial crystn. of glass and can be used as an effective nucleating agent in the SiO2-Al2O3-CaO system.
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    11. 11
      Shahbazian, F.; Sichen, D.; Mills, K. C.; Seetharaman, S. Experimental Studies of Viscosities of Some CaO-CaF2-SiO2 Slags. Ironmaking Steelmaking 1999, 26, 193– 199,  DOI: 10.1179/030192399677068
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      11
      Experimental studies of viscosities of some CaO-CaF2-SiO2 slags
      Shahbazian, F.; Sichen, Du; Mills, K. C.; Seetharaman, S.
      Ironmaking and Steelmaking (1999), 26 (3), 193-199CODEN: IMKSB7; ISSN:0301-9233. (IOM Communications Ltd.)
      In the present work, the viscosities of some CaO-CaF2-SiO2 slags were measured using the rotating cylinder method. The effects of various volatile fluorine compds. on the change in slag compn. are discussed on the basis of thermodn. calcns. The kinetic factors concerning the escape of the volatile fluorides under the exptl. conditions were also examd. It was found that the formation of gaseous species SiF4 was the main source for compositional changes during the viscosity measurements. In the case of CaO-CaF2-SiO2 slags, the formation of SiF4 would be somewhat limited owing to the existence of CaO. The compn. change during the measurements was only about ± 1 wt-% for all components in most cases. Viscosity measurements are reported for slags, based on the post-measurement compns. It was found that the addn. of CaF2 causes a significant decrease in viscosity.
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    12. 12
      Wei, J.; Wang, W.; Zhou, L.; Huang, D.; Zhao, H.; Ma, F. Effect of Na2O and B2O3 on the Crystallization Behavior of Low Fluorine Mold Fluxes for Casting Medium Carbon Steels. Metall. Mater. Trans. B 2014, 45, 643– 652,  DOI: 10.1007/s11663-013-9957-y
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      12
      Effect of Na2O and B2O3 on the crystallization behavior of low fluorine mold fluxes for casting medium carbon steels
      Wei, Juan; Wang, Wanlin; Zhou, Lejun; Huang, Daoyuan; Zhao, Huan; Ma, Fanjun
      Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science (2014), 45 (2), 643-652CODEN: MTBSEO; ISSN:1073-5615. (Springer)
      An investigation was conducted to study the effect of Na2O and B2O3 on the crystn. behavior of low F mold powders for casting medium C (MC) steels. B2O3 tends to lower the crystn. temp. and increase crystn. incubation time of the low F powders; however, Na2O plays an opposite role compared with that of B2O3. The cryst. phase of Ca11Si4B2O22 was formed in Sample D2 [F = 3 pct, Na2O = 10 pct, B2O3 = 8 pct (in wt pct)], which exhibited the most similar crystn. behavior to that of cuspidine, such that Sample D2 showed closest crystn. kinetics to that of a conventional high-F mold slag for casting MC steels. The pptd. cryst. phases for all the samples were analyzed and discussed.
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    13. 13
      Kieffer, J.; Wright, J. P. PyFAI: A Python Library for High Performance Azimuthal Integration on GPU. In Powder Diffraction; Cambridge University Press, 2013; Vol. 28, pp. S339– S350,  DOI: 10.1017/S0885715613000924 .
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      There is no corresponding record for this reference.
    14. 14
      Grajcar, A.; Kuziak, R.; Zalecki, W. Third Generation of AHSS with Increased Fraction of Retained Austenite for the Automotive Industry. Arch. Civ. Mech. Eng. 2012, 12, 334– 341,  DOI: 10.1016/J.ACME.2012.06.011
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      There is no corresponding record for this reference.
    15. 15
      Kim, M. S.; Lee, S. W.; Cho, J. W.; Park, M. S.; Lee, H. G.; Kang, Y. B. A Reaction between High Mn-High Al Steel and CaO-SiO2-Type Molten Mold Flux: Part I. Composition Evolution in Molten Mold Flux. Metall. Mater. Trans. B 2013, 44, 299– 308,  DOI: 10.1007/s11663-012-9770-z
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      15
      A Reaction Between High Mn-High Al Steel and CaO-SiO2-Type Molten Mold Flux: Part I. Composition Evolution in Molten Mold Flux
      Kim, Min-Su; Lee, Su-Wan; Cho, Jung-Wook; Park, Min-Seok; Lee, Hae-Geon; Kang, Youn-Bae
      Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science (2013), 44 (2), 299-308CODEN: MTBSEO; ISSN:1073-5615. (Springer)
      In order to elucidate the reaction mechanism between high Mn-high Al steel such as twin-induced plasticity steel and molten mold flux composed mainly of CaO-SiO2 during continuous casting process, a series of lab.-scale expts. were carried out in the present study. Molten steel and molten flux were brought to react in a refractory crucible in a temp. range between 1713 K to 1823 K (1440 °C to 1550 °C) and compn. evolution in the steel and the flux was analyzed using inductively coupled plasma at. emission spectroscopy, X-ray fluorescence, and electron probe microanal. The amt. of SiO2 in the flux was significantly reduced by Al in the steel; thus, Al2O3 was accumulated in the flux as a result of a chem. reaction, 4[Al] + 3(SiO2) = 3[Si] + 2(Al2O3). In order to find a major factor which governs the reaction, a no. of factors ((pct CaO/pct SiO2), (pct Al2O3), [pct Al], [pct Si], and temp.) were varied in the expts. It was found that the above chem. reaction was mostly governed by [pct Al] in the molten steel. Temp. had a mild effect on the reaction. On the other hand, (pct CaO/pct SiO2), (pct Al2O3), and [pct Si] did not show any noticeable effect on the reaction. Apart from the above reaction, the following reactions are also thought to happen simultaneously: 2[Mn] + (SiO2) = [Si] + 2(MnO) and 2[Fe] + (SiO2) = [Si] + 2(FeO). These oxide components were subsequently reduced by Al in the molten steel. Na2O in the molten flux was gradually decreased and the decrease was accelerated by increasing [pct Al] and temp. Possible reactions affecting the Al2O3 accumulation are summarized.
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    16. 16
      Cho, J.-W.; Blazek, K.; Frazee, M.; Yin, H.; Park, J. H.; Moon, S.-W. Assessment of CaO–Al2O3 Based Mold Flux System for High Aluminum TRIP Casting. ISIJ Int. 2013, 53, 62– 70,  DOI: 10.2355/ISIJINTERNATIONAL.53.62
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      16
      Assessment of CaO-Al2O3 based mold flux system for high aluminum TRIP casting
      Cho, Jung-Wook; Blazek, Kenneth; Frazee, Michael; Yin, Hongbin; Park, Jeong Hyouk; Moon, Sang-Woon
      ISIJ International (2013), 53 (1), 62-70CODEN: IINTEY; ISSN:0915-1559. (Iron and Steel Institute of Japan)
      Today, the demands for Advanced High Strength Steels (AHSS) have gradually increased due to their ability to reduce vehicle wt. as a means to save energy, reduce the environmental impact while simultaneously improving passenger safety. However, AHSS often require the addn. of large amts. of alloying elements such as aluminum and this can make it difficult to cast sound slabs without surface defects. When casting high aluminum AHSS, due to the reaction between aluminum in steel and silica in mold flux, the viscosity and crystn. characteristics of the mold slag changes drastically, and deteriorates mold lubrication. Therefore, it is crit. to limit the reaction between Al in steel and mold slag and at the same time to provide consistent and adequate mold slag in-use properties. This paper describes the development of non-traditional lime-alumina based mold fluxes which have the potential to reduce slag-steel interaction during casting of high aluminum TRIP steel. Several trial casts of 1.45% Al TRIP steel have been conducted on a pilot caster to examine the performance of mold fluxes developed. When the lime-alumina based mold fluxes were applied successfully, alumina pickup was reduced to less than 5% as compared to 15% alumina pickup for corollary trial casts using conventional lime-silica mold fluxes. The developed lime-alumina mold fluxes showed improved in-mold performance as indicated by enhanced lubrication and stable mold heat transfer, again compared to lime-silica fluxes. Cast slabs from the trials using these lime-alumina fluxes have periodic and sound oscillation marks and minimized defects.
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    17. 17
      Li, J.; Kong, B.; Galdino, B.; Xu, J.; Chou, K.; Liu, Q.; Shu, Q. Investigation on Properties of Fluorine-Free Mold Fluxes Based on CaO–Al2O3–B2O3 System. Steel Res. Int. 2017, 88, 1600485,  DOI: 10.1002/srin.201600485
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    18. 18
      Heulens, J.; Blanpain, B.; Moelans, N. Analysis of the Isothermal Crystallization of CaSiO3 in a CaO-Al2O3-SiO2 Melt through in Situ Observations. J. Eur. Ceram. Soc. 2011, 31, 1873– 1879,  DOI: 10.1016/j.jeurceramsoc.2011.03.038
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      18
      Analysis of the isothermal crystallization of CaSiO3 in a CaO-Al2O3-SiO2 melt through in situ observations
      Heulens, J.; Blanpain, B.; Moelans, N.
      Journal of the European Ceramic Society (2011), 31 (10), 1873-1879CODEN: JECSER; ISSN:0955-2219. (Elsevier Ltd.)
      Crystal growth of Wollastonite (CaO.SiO2) in a 42CaO-10Al2O3-48SiO2 melt is obsd. in situ at 1320°C and 1370°C using a high-temp. confocal scanning laser microscope (CSLM). The crystn. is initiated by seeding the melt with Wollastonite particles, which is the primary phase at these temps. and compn. At 1370°C, a faceted growth form is obsd., while at 1320°C, dendritic, nonfaceted growth occurs. The dendrite tip velocity is measured and compared with Ivantsov's theory. The presented exptl. technique proofs to be successful for characterizing isothermal crystn. of minerals in silicate melts.
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    19. 19
      Wang, Z.; Shu, Q.; Chou, K. Crystallization Kinetics of CaO-SiO2(CaO/SiO2=1)-TiO2-10 Mass%B2O3 Glassy Slag by Differential Thermal Analysis. ISIJ Int. 2015, 55, 709– 716,  DOI: 10.2355/isijinternational.55.709
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      19
      Crystallization kinetics of CaO-SiO2(CaO/SiO2 = 1)-TiO2-10 mass%B2O3 glassy slag by differential thermal analysis
      Wang, Zhen; Shu, Qifeng; Chou, Kuochih
      ISIJ International (2015), 55 (4), 709-716CODEN: IINTEY; ISSN:0915-1559. (Iron and Steel Institute of Japan)
      Crystn. characteristics of the CaO-SiO2-TiO2-10%B2O3 glassy slag at w(CaO)/w(SiO2) = 1 have been studied by DTA (DTA) and Matusita-Sakka method. Crystn. products have been distinguished by employing X-ray diffraction (XRD) and SEM equipped with Energy Dispersive Spectroscopy (SEM-EDS). As the TiO2 content is within 10-18%, the crystal phase pptd. is mainly CaSiO3, and the effective activation energies for crystal growth increase with the increase of TiO2 content. Crystn. mechanism for CaSiO3 shifted from surface crystn. to onedimensional growth with increase of TiO2. As the TiO2 content in slag further increases to 22% and 26%, CaTiSiO5 becomes the predominant crystal phase pptd., and the effective activation energies for crystal growth decrease with the increase of TiO2 content. Crystn. mechanism for CaTiSiO5 is mainly surface crystn. Therefore, with the increase of TiO2 content, the crystn. ability of the CaO-SiO2-TiO2-10%B2O3 glass system decreases initially and then increases.
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    20. 20
      Pena, R. B.; Sampaio, D. V.; Lancelotti, R. F.; Cunha, T. R.; Zanotto, E. D.; Pizani, P. S. In-Situ Raman Spectroscopy Unveils Metastable Crystallization in Lead Metasilicate Glass. J. Non-Cryst. Solids 2020, 546, 120254,  DOI: 10.1016/J.JNONCRYSOL.2020.120254
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      20
      In-situ Raman spectroscopy unveils metastable crystallization in lead metasilicate glass
      Pena, R. B.; Sampaio, D. V.; Lancelotti, R. F.; Cunha, T. R.; Zanotto, E. D.; Pizani, P. S.
      Journal of Non-Crystalline Solids (2020), 546 (), 120254CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
      The formation of metastable phases is a relevant, challenging and yet underexplored subject in glass crystn. In this work, we examd. the isothermal crystn. of PbO. SiO2 lead metasilicate glass by using in-situ Raman spectroscopy. We provide evidence for the evolution process from the glass to alamosite, the stable cryst. phase, which is intermediated by two distinct metastable phases at different temps. At 550°C the crystn. pathway proceeded from the low PbSiO3 to alamosite, whereas at 600°C the cryst. phase evolved from the hexagonal PbSiO3 to alamosite. We found no interconversion between these two metastable phases, indicating that both can ppt. prior to alamosite stabilization. These findings demystify the alleged complexity of the crystn. process of lead metasilicate glass, raised in the literature, whose data are critically analyzed and discussed herein.
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    21. 21
      Wang, W.; Xu, H.; Zhai, B.; Zhang, L. A Review of the Melt Structure and Crystallization Behavior of Non-Reactive Mold Flux for the Casting of Advanced High-Strength Steels. Steel Research International; John Wiley & Sons, Ltd 2021, p 2100073.
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    22. 22
      Liu, J.; Yang, K.; Zhai, J.; Shen, B. Effects of Crystallization Temperature on Phase Evolution and Energy Storage Properties of BaO-Na2O-Nb2O5-SiO2-Al2O3 Glass-Ceramics. J. Eur. Ceram. Soc. 2018, 38, 2312– 2317,  DOI: 10.1016/J.JEURCERAMSOC.2018.01.003
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      22
      Effects of crystallization temperature on phase evolution and energy storage properties of BaO-Na2O-Nb2O5-SiO2-Al2O3 glass-ceramics
      Liu, Jingran; Yang, Ke; Zhai, Jiwei; Shen, Bo
      Journal of the European Ceramic Society (2018), 38 (5), 2312-2317CODEN: JECSER; ISSN:0955-2219. (Elsevier Ltd.)
      Barium sodium niobate (BNN) glass ceramics were successfully fabricated with controllable crystn. by technol. for heating processing and the effects of crystn. temps. on phase evolution, microstructure, dielec. properties and breakdown strength were investigated systematically. In addn., the empirical power-law dependence of breakdown strength on thickness (Ebαd-n) was confirmed in BNN glass-ceramic system with an exponent n of 0.21. Based on the results, the BNN glass ceramic crystd. at 800°C presents a remarkable breakdown strength (BDS) of 2322kV/cm with the tested thickness of 30μm, and the highest energy d. of 16.6J/cm3 was achieved.
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    23. 23
      Singh, H.; Shu, Q.; King, G.; Liang, Z.; Wang, Z.; Cao, W.; Huttula, M.; Fabritius, T. Structure and Viscosity of CaO–Al2O3–B2O3–BaO Slags with Varying Mass Ratio of BaO to CaO. J. Am. Ceram. Soc. 2021, 104, 4505– 4517,  DOI: 10.1111/JACE.17877
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      23
      Structure and viscosity of CaO-Al2O3-B2O3-BaO slags with varying mass ratio of BaO to CaO
      Singh, Harishchandra; Shu, Qifeng; King, Graham; Liang, Ziqing; Wang, Zhifeng; Cao, Wei; Huttula, Marko; Fabritius, Timo
      Journal of the American Ceramic Society (2021), 104 (9), 4505-4517CODEN: JACTAW; ISSN:0002-7820. (Wiley-Blackwell)
      The structure of CaO-Al2O3-B2O3-BaO glassy slags with varying mass ratio of BaO to CaO has been investigated by Raman spectroscopy, 11B and 27Al magic angle spinning NMR (MAS-NMR) spectroscopy and at. pair distribution function (PDF). 11B MAS-NMR spectra reveal the dominant coordination of boron as trigonal. Both simulations on 11B MAS-NMR spectra and Raman spectroscopy indicate the presence of orthoborate as the primary borate group with a few borate groups with one bridging oxygen and minor four-coordinated boron sites. 27Al MAS-NMR and PDF show the Al coordination as tetrahedral. Raman spectral study shows that the transverse vibration of AlIV-O-AlIV and AlIV-O-BIII, stretching vibration of aluminate structural units and vibration of orthoborate and pyroborate structural groups. A broader distribution of Al-O bond lengths in PDF also supports the enhanced network connectivity. Viscosity measurements show the increase in viscosity of molten slags with increasing mass ratio of BaO to CaO, which further attributes to the enhanced d.p. of the aluminate network.
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    24. 24
      Shu, Q.; Klug, J. L.; Li, Q. Non-Isothermal Melt Crystallization Kinetics for CaO–Al2O3–B2O3 F-Free Mould Fluxes. ISIJ Int. 2019, 59, 1057– 1063,  DOI: 10.2355/ISIJINTERNATIONAL.ISIJINT-2018-677
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      24
      Non-isothermal melt crystallization kinetics for CaO-Al2O3-B2O3 F-free mould fluxes
      Shu, Qifeng; Klug, Jeferson Leandro; Li, Qiangqi
      ISIJ International (2019), 59 (6), 1057-1063CODEN: IINTEY; ISSN:0915-1559. (Iron and Steel Institute of Japan)
      Efforts have been made to develop fluorine-free mold fluxes for the continuous casting of steel process. In this work the crystn. behavior of fluorine-free mold slags based on the CaO-Al2O3-B2O3 system was investigated by differential scanning calorimeter (DSC) and SEM equipped with energy dispersive spectroscopy(SEM-EDS). The crystn. kinetics for Ca3Al2O6 primary crystals was analyzed by combining modified Avrami anal. with Friedman isoconversional method. Avrami parameter n is close to 4 for samples with the ratios w(CaO)/w(Al2O3) = 1 and w(CaO)/w(Al2O3) = 1.2, indicating a crystn. mechanism of continuous bulk nucleation and 3D crystal growth. The Avrami parameter n for samples with w(CaO)/w(Al2O3) = 0.9 is close to 3, indicating instantaneous bulk nucleation and 3D crystal growth. The crystn. rate const. is the highest and half crystn. time is the lowest for the samples with w(CaO)/w(Al2O3) = 0.9, indicating the fastest crystn. In the initial stage, effective activation energies were mainly detd. by the undercooling values. In the final stage, kinetic barrier for crystn. could have some influence on crystn.; for the investigated mold fluxes crystn. in the final stage is retarded by increasing w(CaO)/w(Al2O3) ratio. Thus crystn. mechanisms were elucidated and effective activation energy of crystn. for the first crystal which ppts. from melt was detd.
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    25. 25
      Gomez, A.; Dina, G.; Kycia, S. The High-Energy x-Ray Diffraction and Scattering Beamline at the Canadian Light Source. Rev. Sci. Instrum. 2018, 89, 063301  DOI: 10.1063/1.5017613
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      The high-energy x-ray diffraction and scattering beamline at the Canadian Light Source
      Gomez, A.; Dina, G.; Kycia, S.
      Review of Scientific Instruments (2018), 89 (6), 063301/1-063301/8CODEN: RSINAK; ISSN:0034-6748. (American Institute of Physics)
      The optical design for the high-energy x-ray diffraction and scattering beamline of the Brockhouse sector at the Canadian Light Source is described. The design is based on a single side-bounce silicon focusing monochromator that steers the central part of a high-field permanent magnet wiggler beam into the exptl. station. Two different configurations are proposed: a higher energy resoln. with vertical focusing and a lower energy resoln. with horizontal and vertical focusing. The monochromator will have the possibility of mounting three crystals: one crystal optimized for 35 keV that focuses in the horizontal and vertical directions using reflection (1,1,1) and two other crystals both covering the energies above 40 keV: one with only vertical focusing and another one with horizontal and vertical focusing. The geometry of the last two monochromator crystals was optimized to use reflections (4,2,2) and (5,3,3) to cover the broad energy range from 40 to 95 keV. (c) 2018 American Institute of Physics.
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      Chupas, P. J.; Chapman, K. W.; Kurtz, C.; Hanson, J. C.; Lee, P. L.; Grey, C. P. A Versatile Sample-Environment Cell for Non-Ambient X-Ray Scattering Experiments. J. Appl. Crystallogr. 2008, 41, 822– 824,  DOI: 10.1107/S0021889808020165
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      A versatile sample-environment cell for non-ambient X-ray scattering experiments
      Chupas, Peter J.; Chapman, Karena W.; Kurtz, Charles; Hanson, Jonathan C.; Lee, Peter L.; Grey, Clare P.
      Journal of Applied Crystallography (2008), 41 (4), 822-824CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)
      A compact reaction cell is described for in-situ expts. requiring control of both the temp. of the sample and the atm. over the sample. The cell incorporates an optional furnace capable of temps. of up to ∼1273 K. The compact design and ability of the cell to mount directly on a std. goniometer head allows portability to a large no. of diffraction instruments at synchrotron sources.
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      Toby, B. H.; Von Dreele, R. B. GSAS-II: The Genesis of a Modern Open-Source All Purpose Crystallography Software Package. J. Appl. Crystallogr. 2013, 46, 544– 549,  DOI: 10.1107/S0021889813003531
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      GSAS-II: the genesis of a modern open-source all purpose crystallography software package
      Toby, Brian H.; Von Dreele, Robert B.
      Journal of Applied Crystallography (2013), 46 (2), 544-549CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)
      The newly developed GSAS-II software is a general purpose package for data redn., structure soln. and structure refinement that can be used with both single-crystal and powder diffraction data from both neutron and x-ray sources, including lab. and synchrotron sources, collected on both two- and 1-dimensional detectors. It is intended that GSAS-II will eventually replace both the GSAS and the EXPGUI packages, as well as many other utilities. GSAS-II is open source and is written largely in object-oriented Python but offers speeds comparable to compiled code because of its reliance on the Python NumPy and SciPy packages for computation. It runs on all common computer platforms and offers highly integrated graphics, both for a user interface and for interpretation of parameters. The package can be applied to all stages of crystallog. anal. for const.-wavelength x-ray and neutron data. Plans for considerable addnl. development are discussed.
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      Toraya, H. A New Method for Quantitative Phase Analysis Using X-Ray Powder Diffraction: Direct Derivation of Weight Fractions from Observed Integrated Intensities and Chemical Compositions of Individual Phases. J. Appl. Crystallogr. 2016, 49, 1508– 1516,  DOI: 10.1107/S1600576716010451
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      A new method for quantitative phase analysis using X-ray powder diffraction: direct derivation of weight fractions from observed integrated intensities and chemical compositions of individual phases
      Toraya, Hideo
      Journal of Applied Crystallography (2016), 49 (5), 1508-1516CODEN: JACGAR; ISSN:1600-5767. (International Union of Crystallography)
      A new method for the quant. phase anal. of multi-component polycryst. materials using the X-ray powder diffraction technique is proposed. A formula for calcg. wt. fractions of individual cryst. phases has been derived from the intensity formula for powder diffraction in Bragg-Brentano geometry. The integrated intensity of a diffraction line is proportional to the vol. fraction of a relevant cryst. phase in an irradiated sample, and the vol. fraction, when it is multiplied with the chem. formula wt., can be related to the wt. fraction. The structure-factor-related quantity in the intensity formula, when it is summed in an adequate 2θ range, can be replaced with the sum of squared nos. of electrons belonging to composing atoms in the chem. formula. Unit-cell vols. and the no. of chem. formula units are all cancelled out in the formula. Therefore, the formula requires only single-measurement integrated intensity datasets for the individual phases and their chem. compns. No std. ref. material, ref. intensity ratio or crystal structure parameter is required. A new procedure for partitioning the intensities of unresolved overlapped diffraction lines has also been proposed. It is an iterative procedure which starts from derived wt. fractions, converts the wt. fractions to vol. fractions by utilizing addnl. information on material densities, and then partitions the intensities in proportion to the vol. fractions. Use of the Pawley pattern decompn. method provides more accurate intensity datasets than the individual profile fitting technique, and it expands the applicability of the present method to more complex powder diffraction patterns. Test results using weighed mixt. samples showed that the accuracy, evaluated by the root-mean-square error, is comparable to that obtained by Rietveld quant. phase anal.
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      Tian, K. V.; Yang, B.; Yue, Y.; Bowron, D. T.; Mayers, J.; Donnan, R. S.; Dobó-Nagy, C.; Nicholson, J. W.; Fang, D. C.; Greer, A. L.; Chass, G. A.; Greaves, G. N. Atomic and Vibrational Origins of Mechanical Toughness in Bioactive Cement during Setting. Nat. Commun. 2015, 6, 1– 10,  DOI: 10.1038/ncomms9631
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      Zheng, Q.; Zhang, Y.; Montazerian, M.; Gulbiten, O.; Mauro, J. C.; Zanotto, E. D.; Yue, Y. Understanding Glass through Differential Scanning Calorimetry. Chem. Rev. 2019, 119, 7848– 7939,  DOI: 10.1021/ACS.CHEMREV.8B00510
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      Understanding Glass through Differential Scanning Calorimetry
      Zheng, Qiuju; Zhang, Yanfei; Montazerian, Maziar; Gulbiten, Ozgur; Mauro, John C.; Zanotto, Edgar D.; Yue, Yuanzheng
      Chemical Reviews (Washington, DC, United States) (2019), 119 (13), 7848-7939CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
      A review. Differential scanning calorimetry (DSC) is a powerful tool to address some of the most challenging issues in glass science and technol., such as the nonequil. nature of the glassy state and the detailed thermodn. and kinetics of glass-forming systems during glass transition, relaxation, rejuvenation, polyamorphic transition, and crystn. The utility of the DSC technique spans across all glass-forming chemistries, including oxide, chalcogenide, metallic, and org. systems, as well as recently discovered metal-org. framework glass-forming systems. Here we present a comprehensive review of the many applications of DSC in glass science with focus on glass transition, relaxation, polyamorphism, and crystn. phenomena. We also emphasize recent advances in DSC characterization technol., including flash DSC and temp.-modulated DSC. This review demonstrates how DSC studies have led to a multitude of relevant advances in the understanding of glass physics, chem., and even technol.
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      Kuczek, J.; Sułowska, J.; Lach, R.; Szumera, M. The Glass Formation and Crystallization Studies on Iron Phosphate–Silicate Glasses. J. Therm. Anal. Calorim. 2019, 138, 1953– 1964,  DOI: 10.1007/S10973-019-08523-Y/FIGURES/6
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      The glass formation and crystallization studies on iron phosphate-silicate glasses
      Kuczek, Justyna; Sulowska, Justyna; Lach, Radoslaw; Szumera, Magdalena
      Journal of Thermal Analysis and Calorimetry (2019), 138 (3), 1953-1964CODEN: JTACF7; ISSN:1388-6150. (Springer)
      The assessment of impact of incorporation of various amt. of Fe2O3 at the expense of MgO and CaO on the glassy phase formation and thermal stability exhibited in P2O5-SiO2-K2O-MgO-CaO-Fe2O3 system was carried out. The characteristic temps. for iron phosphate-silicate glasses and glass-cryst. materials were designated from assocd. DSC curves. Selected samples were subjected to the process of induced crystn., and products combined with particular exothermic effects were identified. Combination of DSC, XRD and SEM-EDS methods enabled to collect invaluable data concerning the course of crystn. of not only iron phosphate-silicate glasses subjected to the process of induced crystn., but also glass-cryst. materials obtained directly through melt-quenched technique. The amt. of particular cryst. products assocd. with selected devitrificates was detd. via Rietveld technique. Results of the conducted study indicated that Fe2O3 addn. conduces to the decrease in crystn. temps. and thermal stability which was reflected in calcd. values of ΔT and KW parameters. Concomitantly, glass with 20 mol% iron (III) oxide addn. exhibited significantly improved, distinctive thermal stability among the materials in the analyzed series. The performed study is a contribution to the knowledge of iron phosphate glasses family and assocd. glass-cryst. materials.
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      Lusvardi, G.; Malavasi, G.; Menabue, L.; Menziani, M. C. Synthesis, Characterization, and Molecular Dynamics Simulation Of Na2O–CaO–SiO2–ZnO Glasses. J. Phys. Chem. B 2002, 106, 9753– 9760,  DOI: 10.1021/JP020321S
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      Synthesis, Characterization, and Molecular Dynamics Simulation Of Na2O-CaO-SiO2-ZnO Glasses
      Lusvardi, G.; Malavasi, G.; Menabue, L.; Menziani, M. C.
      Journal of Physical Chemistry B (2002), 106 (38), 9753-9760CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
      The glass of compn. Na2O·CaO·2SiO2 was modified upon addn. of ZnO to obtain the series of glasses Na2O·CaO·2SiO2·xZnO (x = 0.17, 0.34, 0.68), where x = 0.68 is the exptl. detd. max. zinc content that does not produce phase sepn. The glasses were investigated by means of d. and thermal measurements (glass-transition and crystn. temps.); moreover, the phases sepd. upon crystn. were identified. The results of mol. dynamics (MD) simulations combined with the anal. of the crystal structure of the main phases sepd. (Na2Ca(SiO3)2 and Na2ZnSiO4) provided insights into the structural role of zinc and its effect on the short- and medium-range order of the glass structures.
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      Zheng, W.; Cao, H.; Zhong, J.; Qian, S.; Peng, Z.; Shen, C. CaO–MgO–Al2O3–SiO2 Glass-Ceramics from Lithium Porcelain Clay Tailings for New Building Materials. J. Non-Cryst. Solids 2015, 409, 27– 33,  DOI: 10.1016/J.JNONCRYSOL.2014.11.002
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      CaO-MgO-Al2O3-SiO2 glass-ceramics from lithium porcelain clay tailings for new building materials
      Zheng, Weihong; Cao, Hua; Zhong, Jingbo; Qian, Shaoyang; Peng, Zhigang; Shen, Chunhua
      Journal of Non-Crystalline Solids (2015), 409 (), 27-33CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
      Lithium porcelain clay tailings (contg. 1.2 wt.% Li2O) blended with other chem. raw materials were used to develop a new glass-ceramic of CaO-MgO-Al2O3-SiO2 system for rolling process. The effects of TiO2 and ZnO oxides on melting and crystn. behaviors of glasses were investigated by DTA, XRD, EPMA and viscosity test. The results showed that melting temp., forming temp. and glass transition temp. (Tg) of glasses were decreased with the increase of ZnO addn. Nevertheless, the crystn. temp. was shifted from 864 to 901 °C when the addn. of TiO2 decreased from 2 wt.% to 0.5 wt.%. Diopside as a major cryst. phase and spinel as a minor phase are pptd. in M3 specimen with 2.5 wt.% ZnO and 0.5 wt.% TiO2. The columnar and granular cryst. phases were distributed in M3 specimen nucleated at 750°C for 2 h and followed by crystn. at 1110°C for 2 h, which resulted in proper appearance suitable for decorative materials.
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      Grangeon, S.; Fernandez-Martinez, A.; Baronnet, A.; Marty, N.; Poulain, A.; Elkaïm, E.; Roosz, C.; Gaboreau, S.; Henocq, P.; Claret, F. Quantitative X-Ray Pair Distribution Function Analysis of Nanocrystalline Calcium Silicate Hydrates: A Contribution to the Understanding of Cement Chemistry. J. Appl. Crystallogr. 2017, 50, 14– 21,  DOI: 10.1107/S1600576716017404
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      Quantitative X-ray pair distribution function analysis of nanocrystalline calcium silicate hydrates: a contribution to the understanding of cement chemistry
      Grangeon, Sylvain; Fernandez-Martinez, Alejandro; Baronnet, Alain; Marty, Nicolas; Poulain, Agnieszka; Elkaim, Erik; Roosz, Cedric; Gaboreau, Stephane; Henocq, Pierre; Claret, Francis
      Journal of Applied Crystallography (2017), 50 (1), 14-21CODEN: JACGAR; ISSN:1600-5767. (International Union of Crystallography)
      A review. The structural evolution of nanocryst. calcium silicate hydrate (C-S-H) as a function of its calcium to silicon (Ca/Si) ratio has been probed using qual. and quant. X-ray at. pair distribution function anal. of synchrotron X-ray scattering data. Whatever the Ca/Si ratio, the C-S-H structure is similar to that of tobermorite. When the Ca/Si ratio increases from ∼0.6 to ∼1.2, Si wollastonite-like chains progressively depolymerize through preferential omission of Si bridging tetrahedra. When the Ca/Si ratio approaches ∼1.5, nanosheets of portlandite are detected in samples aged for 1 d, while microcryst. portlandite is detected in samples aged for 1 yr. High-resoln. transmission electron microscopy imaging shows that the tobermorite-like structure is maintained to Ca/Si > 3.
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      Luz, A. P.; Pandolfelli, V. C. Halting the Calcium Aluminate Cement Hydration Process. Ceram. Int. 2011, 37, 3789– 3793,  DOI: 10.1016/j.ceramint.2011.06.034
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      Halting the calcium aluminate cement hydration process
      Luz, A. P.; Pandolfelli, V. C.
      Ceramics International (2011), 37 (8), 3789-3793CODEN: CINNDH; ISSN:0272-8842. (Elsevier Ltd.)
      Ca aluminate cement reactions with H2O result in anhyd. phases dissoln., followed by nucleation and crystal growth of hydrate compds. Due to the dynamic characteristics of this process and to evaluate the phase transformation kinetics of such materials, suitable methods to halt hydration are required. The use of acetone and microwave drying, aiming to withdraw free H2O and inhibit further reactions, was evaluated. X-ray diffraction was used to quantify the phases generated in the cement samples kept at 37° for 1-15 days. The advantages and drawbacks of these procedures are presented and discussed. Using microwaves to halt the hydration process in shaped samples seems to be effective to withdraw the cement free H2O, if a previous grinding of the material is carried out. The procedure suggested can be used in researches in the refractory castable area, endodontic cements and others.
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      Christensen, A. N.; Fjellvåg, H.; Lehmann, M. S. Time Resolved Powder Neutron Diffraction Investigations of Reactions of Solids with Water. Cem. Concr. Res. 1986, 16, 871– 874,  DOI: 10.1016/0008-8846(86)90010-4
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      Malfait, W. J.; Xue, X. The Nature of Hydroxyl Groups in Aluminosilicate Glasses: Quantifying Si-OH and Al-OH Abundances along the SiO2-NaAlSiO4 Join by 1H, 27Al-1H and 29Si-1H NMR Spectroscopy. Geochim. Cosmochim. Acta 2010, 74, 719– 737,  DOI: 10.1016/j.gca.2009.10.036
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      The nature of hydroxyl groups in aluminosilicate glasses: Quantifying Si-OH and Al-OH abundances along the SiO2-NaAlSiO4 join by 1H, 27Al-1H and 29Si-1H NMR spectroscopy
      Malfait, Wim J.; Xue, Xianyu
      Geochimica et Cosmochimica Acta (2010), 74 (2), 719-737CODEN: GCACAK; ISSN:0016-7037. (Elsevier B.V.)
      The combined results of 27Al-1H and 1H-29Si-1H cross polarization NMR expts. for hydrous glasses (contg. 0.5-2 wt% water) along the SiO2-NaAlSiO4 join confirm that the dissoln. mechanism of water in aluminosilicate glasses is fundamentally the same as for Al-free systems, i.e. the dissolved water ruptures oxygen bridges and creates Si-OH and Al-OH groups, in addn. to forming mol. water (H2Omol). The fraction of Al-OH increases non-linearly as the Al content increases with up to half of the OH groups as Al-OH for compns. close to NaAlSiO4. The relative abundances of the different species are controlled by the degree of Al-avoidance and the relative tendency of hydrolysis of the different types of oxygen bridges, Si-O-Si, Si-O-Al and Al-O-Al. A set of homogeneous reactions is derived to model the measured Al-OH/Si-OH speciation, and the obtained equil. consts. are in agreement with literature data on the degree of Al-avoidance. With these equil. consts., the abundance of the different oxygen species, i.e. Si-O-Si, Si-O-Al, Al-O-Al, Si-OH, Al-OH and H2Omol, can be predicted for the entire range of water and Al contents.
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      Bauchy, M.; Qomi, M. J. A.; Ulm, F. J.; Pellenq, R. J.-M. Order and Disorder in Calcium-Silicate-Hydrate. J. Chem. Phys. 2014, 140, 214503,  DOI: 10.1063/1.4878656
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      Order and disorder in calcium-silicate-hydrate
      Bauchy, M.; Abdolhosseini Qomi, M. J.; Ulm, F.-J.; Pellenq, R. J.-M.
      Journal of Chemical Physics (2014), 140 (21), 214503/1-214503/9CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)
      Despite advances in the characterization and modeling of cement hydrates, the at. order in Ca-Silicate-Hydrate (C-S-H), the binding phase of cement, remains an open question. Indeed, in contrast to the former cryst. model, recent mol. models suggest that the nanoscale structure of C-S-H is amorphous. To elucidate this issue, the authors analyzed the structure of a realistic simulated model of C-S-H, and compared the latter to cryst. tobermorite, a natural analog of C-S-H, and to an artificial ideal glass. C-S-H appears as amorphous, when averaged on all atoms. However, an anal. of the order around each at. species reveals that its structure shows an intermediate degree of order, retaining some characteristics of the crystal while acquiring an overall glass-like disorder. Thanks to a detailed quantification of order and disorder, while C-S-H retains some signatures of a tobermorite-like layered structure, hydrated species are completely amorphous. (c) 2014 American Institute of Physics.
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      Gates-Rector, S.; Blanton, T. The Powder Diffraction File: A Quality Materials Characterization Database. Powder Diffr. 2019, 34, 352– 360,  DOI: 10.1017/S0885715619000812
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      The Powder Diffraction File: a quality materials characterization database
      Gates-Rector, Stacy; Blanton, Thomas
      Powder Diffraction (2019), 34 (4), 352-360CODEN: PODIE2; ISSN:0885-7156. (Cambridge University Press)
      The ICDD's Powder Diffraction File (PDF) is a database of inorg. and org. diffraction data used for phase identification and materials characterization by powder diffraction. The PDF has been available for over 75 years and finds application in X-ray, synchrotron, electron, and neutron diffraction analyses. With entries based on powder and single crystal data, the PDF is the only crystallog. database where every entry is editorially reviewed and marked with a quality mark that alerts the user to the reliability/quality of the submitted data. The editorial processes of ICDD's quality management system are unique in that they are ISO 9001:2015 certified. Initially offered as text on paper cards and books, the PDF evolved to a computer-readable database in the 1960s and today is both computer and web accessible. With data mining and phase identification software available in PDF products, and the databases' compatibility with vendor (third party) software, the 1 000 000+ published PDF entries serve a wide range of disciplines covering academic, industrial, and government labs. Details describing the content of database entries are presented to enhance the use of the PDF.
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      Egami, T.; Billinge, S. J. L. Underneath the Bragg Peaks: Structural Analysis of Complex Materials; Elsevier, 2003.
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      Petkov, V.; Billinge, S. J. L.; Shastri, S. D.; Himmel, B. High-Resolution Atomic Distribution Functions of Disordered Materials by High-Energy X-Ray Diffraction. J. Non-Cryst. Solids 2001, 293-295, 726– 730,  DOI: 10.1016/S0022-3093(01)00864-X
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      High-resolution atomic distribution functions of disordered materials by high-energy x-ray diffraction
      Petkov, V.; Billinge, S. J. L.; Shastri, S. D.; Himmel, B.
      Journal of Non-Crystalline Solids (2001), 293-295 (), 726-730CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier Science B.V.)
      The at.-scale structure of materials with different degrees of structural disorder has been investigated by high-energy (E ≥60 keV) X-ray diffraction. Good quality structure functions extended to wave vectors of magnitude Q ≥40 Å-1 have been obtained even in case of materials composed of weakly scattering, light at. species. The corresponding high-resoln. at. distribution functions allowed fine structural features differing in as little as (0.14 Å) to be resolved. In particular, the distinct Ga-As (∼2.43 Å) and In-As (2.61 Å) bonds in In-Ga-As alloys have been differentiated. The at.-scale structure of 'restacked' WS2 has been detd. and the presence of three distinct W-W distances occurring at 2.77, 3.27 and 3.85 Å established. Finally, Si-O (∼1.61 Å), Al-O (∼1.75 Å) and Ca-O (∼2.34 Å) bonds in calcium aluminosilicate glasses have been differentiated and the characteristics of the resp. co-ordination polyhedra revealed.
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      Gedekar, K. A.; Wankhede, S. P.; Moharil, S. V.; Belekar, R. M. Synthesis, Crystal Structure and Luminescence in Ca3Al2O6. J. Mater. Sci.: Mater. Electron. 2018, 29, 6260– 6265,  DOI: 10.1007/s10854-018-8603-5
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      Synthesis, crystal structure and luminescence in Ca3Al2O6
      Gedekar, K. A.; Wankhede, S. P.; Moharil, S. V.; Belekar, R. M.
      Journal of Materials Science: Materials in Electronics (2018), 29 (8), 6260-6265CODEN: JSMEEV; ISSN:0957-4522. (Springer)
      Bluish green emitting phosphor, Ca3Al2O6:Ce3+, is prepd. by low-temp. combustion method. X-ray diffraction, photoluminescence, SEM techniques are used to characterize the synthesized phosphor. The most efficient bluish green (483 nm) emission is obsd. under the excitation by near UV light. The emission characteristics are credited to 5d → 4f type transitions in Ce3+. The luminescence properties of Eu2+ are predicted for the first time from those of Ce3+. Also, photoluminescence of Eu3+ is studied in the same host. The emission spectrum of Ca3Al2O6:Eu3+ shows the peak at 592 (orange) and 614 nm (red) wavelengths. Ca3Al2O6:Ce3+phosphor can be a potential blue phosphor for field emission display, solid-state lighting and LED.
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      Huang, X. H.; Liao, J. L.; Zheng, K.; Hu, H. H.; Wang, F. M.; Zhang, Z. T. Effect of B2O3 Addition on Viscosity of Mould Slag Containing Low Silica Content. Ironmaking Steelmaking 2014, 41, 67– 74,  DOI: 10.1179/1743281213Y.0000000107
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      Effect of B2O3 addition on viscosity of mould slag containing low silica content
      Huang, X. H.; Liao, J. L.; Zheng, K.; Hu, H. H.; Wang, F. M.; Zhang, Z. T.
      Ironmaking & Steelmaking (2014), 41 (1), 67-74CODEN: IMKSB7; ISSN:0301-9233. (Maney Publishing)
      The viscosity of SiO2-30Al2O3-B2O3-12Na2O-CaO slag system (CaO/SiO2 = 2·68-7·35, B2O3 = 0-9 wt-%) was investigated in the present study. The objective is to study the influence of B2O3 on the viscosity and structure of mold slags contg. low silica content. The research of the low silica slag system is meaningful because of it is less reactive with Al during continuous casting of steels contg. high amts. of dissolved aluminum, such as transformation induced plasticity assisted steels. The viscosities of these quinternary slags decreased slightly with an increase in the content of additive B2O3 above the break temp. The apparent activation energy of viscous flow was found to decrease with increasing B2O3 content. The break temp. also decreased with increasing B2O3 content. Based on the exptl. data, the decrease in break temp. per mol.-% B2O3 ΔTbr is 15·23 K. An empirical model was then established to predict the break temp. of mold slags contg. B2O3, and the deviation is between -25 and +25 K. Based on the viscosity and Fourier transform IR anal., it is proposed that the three-coordinated boron is dominated in these slags over the entire compositional range, and the borosilicate networks are loosened with increasing B2O3 content in the present study. The Riboud model was modified empirically based on the present exptl. data, and the mean deviation is ∼13%.
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      Bi, Z.; Li, K.; Jiang, C.; Zhang, J.; Ma, S.; Sun, M.; Wang, Z.; Li, H. Effects of B2O3 on the Structure and Properties of Blast Furnace Slag by Molecular Dynamics Simulation. J. Non-Cryst. Solids 2021, 551, 120412,  DOI: 10.1016/J.JNONCRYSOL.2020.120412
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      Effects of B2O3 on the structure and properties of blast furnace slag by molecular dynamics simulation
      Bi, Zhisheng; Li, Kejiang; Jiang, Chunhe; Zhang, Jianliang; Ma, Shufang; Sun, Minmin; Wang, Ziming; Li, Hongtao
      Journal of Non-Crystalline Solids (2021), 551 (), 120412CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
      B2O3 has the advantages of reducing the liquidus temp. and enhancing the fluidity of slag, while its influence mechanism in at. scale has not yet been fully understood. Mol. dynamics simulation was conducted to investigate the influence of B2O3 on the structure and properties of SiO2-CaO-Al2O3-B2O3 blast furnace slag system at 1773 K. Results showed that a large no. of [SiO4]4--[BO3]3- structures are generated in the system after B2O3 added, Si4+ ions mainly exist in the form of [SiO4]4- tetrahedrons and B3+ ions mainly exist in the form of [BO3]3- planar triangular structures and [BO4]5- tetrahedrons. With the increase of B2O3 content, the proportion of [BO3]3- planar triangular structures increase. In addn., the content of bridge oxygen in the microstructure of slag increases obviously, the content of non-bridge oxygen decreases, and the polymn. degree of the system increases somewhat. Through the anal. of microscopic mechanism and the modified NPL viscosity model, combined with exptl. data, the truth that the slag viscosity decreases with the increase of B2O3 contents were known in the simulated concn. range.
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    46. 46
      Yadav, A. K.; Singh, P. A Review of the Structures of Oxide Glasses by Raman Spectroscopy. RSC Adv. 2015, 5, 67583– 67609,  DOI: 10.1039/C5RA13043C
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      A review of the structures of oxide glasses by Raman spectroscopy
      Yadav, Avadhesh Kumar; Singh, Prabhakar
      RSC Advances (2015), 5 (83), 67583-67609CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)
      The family of oxide glasses is very wide and it is continuously developing. The rapid development of advanced and innovative glasses is under progress. Oxide glasses have a variety of applications in articles for daily use as well as in advanced technol. fields such as X-ray protection, fiber glasses, optical instruments and lab glassware. Oxide glasses basically consist of network formers, such as borate, silicate, phosphate, borosilicate, borophosphate, and network modifiers such as alkali, alk. earth and transition metals. In the present review article, Raman spectroscopy results for the structures of borate, silicate, phosphate, borosilicate, borophosphate, aluminosilicate, phosphosilicate, alumino-borosilicate and tellurite glasses are summarized.
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      Aguiar, H.; Serra, J.; González, P.; León, B. Structural Study of Sol–Gel Silicate Glasses by IR and Raman Spectroscopies. J. Non-Cryst. Solids 2009, 355, 475– 480,  DOI: 10.1016/J.JNONCRYSOL.2009.01.010
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      Structural study of sol-gel silicate glasses by IR and Raman spectroscopies
      Aguiar, H.; Serra, J.; Gonzalez, P.; Leon, B.
      Journal of Non-Crystalline Solids (2009), 355 (8), 475-480CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
      A study of the structure and bonding configuration of sol-gel silicate glasses by Raman and IR spectroscopies is presented. Moreover, a review of the Raman lines and IR bands assignment, the identification of the non-bridging silicon-oxygen groups and the ring structures are also demonstrated. The evolution of the changes of the bonding configuration in the compn. and the stabilization temp. of the bioactive glasses is discussed in terms of the structural and textural characteristics of the glasses. Raman and IR analyses contribute to the improvement in understanding of the local symmetry for sol-gel silicate glasses. IR spectroscopy has allowed to identify the vibration bands of the hydroxyl groups assocd. with various configurations of the terminal silanol bonds on the glass surface and the free mol. water in the glass matrix. Raman anal. has provided an alternative method of quantifying the network connectivity grade and predicting the textural properties of the sol-gel silicate glasses.
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      Li, H.; Hrma, P.; Vienna, J. D.; Qian, M.; Su, Y.; Smith, D. E. Effects of Al2O3, B2O3, Na2O, and SiO2 on Nepheline Formation in Borosilicate Glasses: Chemical and Physical Correlations. J. Non-Cryst. Solids 2003, 331, 202– 216,  DOI: 10.1016/j.jnoncrysol.2003.08.082
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      Effects of Al2O3, B2O3, Na2O, and SiO2 on nepheline formation in borosilicate glasses: chemical and physical correlations
      Li, Hong; Hrma, Pavel; Vienna, John D.; Qian, Maoxu; Su, Yali; Smith, Donald E.
      Journal of Non-Crystalline Solids (2003), 331 (1-3), 202-216CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier Science B.V.)
      Raman spectroscopy was applied to complex sodium aluminoborosilicate glasses that ppt. nepheline as their primary phase. The main focus was on the Raman band at 850 cm-1 (wavenumber) obsd. in quenched glasses. Based on the literature, the 850 cm-1 band was assigned to AlIV-O-Si units in which tetrahedral AlIV are substituted for Si in the network, creating [AlO4/2]- anions that are charge-balanced by Na+ cations. The same glasses with various temp. histories were examd. with optical microscopy, SEM and TEM. The results indicated that the 850 cm-1 Raman band was assocd. with nanocrystals that formed in the melts and were preserved in the quenched samples. The chem. of these nanocrystals resembled nepheline. Models relating the intensity of the Raman band at 850 cm-1 and the liquidus temp. (TL) to glass compn. revealed that a relationship exists between these two properties. An increase in B2O3 and SiO2 decreased the Raman band intensity and the TL, whereas an increase in Al2O3 and Na2O increased both properties. These effects were attributed to the influence of various oxides on the Na+-[AlO4/2]- activity in the melt.
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      Kim, G. H.; Sohn, I. Role of B2O3 on the Viscosity and Structure in the CaO-Al2O3-Na2O-Based System. Metall. Mater. Trans. B 2014, 45, 86– 95,  DOI: 10.1007/s11663-013-9953-2
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      Role of B2O3 on the Viscosity and Structure in the CaO-Al2O3-Na2O-Based System
      Kim, Gi Hyun; Sohn, Il
      Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science (2014), 45 (1), 86-95CODEN: MTBSEO; ISSN:1073-5615. (Springer)
      The effect of B2O3 on the viscosity and structure in the calcium-aluminate melt flux system contg. Na2O was studied. An increase in the B2O3 content at fixed CaO/Al2O3 ratio lowered the viscosity. Higher CaO/Al2O3 ratio at fixed B2O3 content also decreased the viscosity. The alumino-borate structures were confirmed through Fourier transformed IR (FTIR) and Raman spectroscopy and consisted of [AlO4]-tetrahedral structural units, [BO3]-triangular structural units, and [BO4]-tetrahedral structural units, which could be correlated to the viscosity. At fixed CaO/Al2O3 ratio, B2O3 addns. decreased the [AlO4]-tetrahedral structural units and transformed the 3-D network structures such as pentaborate and tetraborate into 2-D network structures of boroxol and boroxyl rings by breaking the bridged oxygen atoms (O0) to produce non-bridged oxygen atoms (O-) leading to a decrease in the molten flux viscosity. At fixed B2O3 contents and higher CaO/Al2O3 ratio, 3-D complex network structures become 3-D simple and 2-D isolated network structures, resulting in lower viscosities. The apparent activation energy for viscous flow varied from 132 to 249 kJ/mol according to the compn. of B2O3 and CaO/Al2O3 ratio.
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    50. 50
      Torréns-Martín, D.; Fernández-Carrasco, L.; Martínez-Ramírez, S.; Ibáñez, J.; Artús, L.; Matschei, T. Raman Spectroscopy of Anhydrous and Hydrated Calcium Aluminates and Sulfoaluminates. J. Am. Ceram. Soc. 2013, 96, 3589– 3595,  DOI: 10.1111/JACE.12535
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      Raman Spectroscopy of Anhydrous and Hydrated Calcium Aluminates and Sulfoaluminates
      Torrens-Martin, David; Fernandez-Carrasco, Lucia; Martinez-Ramirez, Sagrario; Ibanez, Jordi; Artus, Lluis; Matschei, Thomas
      Journal of the American Ceramic Society (2013), 96 (11), 3589-3595CODEN: JACTAW; ISSN:0002-7820. (Wiley-Blackwell)
      Recent investigations have revealed the great potential of Raman spectroscopy for the characterization of clinker minerals and com. portland cements. The usefulness of this technique for the identification of anhyd., hydrated, and carbonated phases in cement-based materials has been demonstrated. In the present work, the application of micro-Raman spectroscopy for the characterization of the main clinker phases of calcium aluminate cements and calcium sulfoaluminate cement is explored. The main stable hydrated phases as well as several important carbonated phases are investigated. Raman measurements on the following phases are reported: (i) pure, unhydrated phases: CA, C12A7, CA2, C2AS, cubic C3A, C4AF, and C4A3; (ii) hydrated phases: ettringite, monosulfoaluminate, and hydrogarnet (C3AH6); (iii) carboaluminate phases: hemicarboaluminate and monocarboaluminate. The present results, which are discussed in terms of the internal vibrational modes of the aluminate, carbonate, and sulfate mol. groups as well as stretching O-H vibrations, show the ability of Raman spectroscopy to identify the main hydrated and unhydrated phases in the aluminate and sulfoaluminate cements. The Raman spectra obtained in this work provide an extended database to the existing data published in the literature.
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      Licheron, M.; Montouillout, V.; Millot, F.; Neuville, D. R. Raman and 27Al NMR Structure Investigations of Aluminate Glasses: (1 - X)Al2O3 - x MO, with M = Ca, Sr, Ba and 0.5 < x < 0.75. J. Non-Cryst. Solids 2011, 357, 2796– 2801,  DOI: 10.1016/j.jnoncrysol.2011.03.001
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      Raman and 27Al NMR structure investigations of aluminate glasses: (1-x)Al2O3-xMO, with M = Ca, Sr, Ba and 0.5< x< 0.75)
      Licheron, Marina; Montouillout, Valerie; Millot, Francis; Neuville, Daniel R.
      Journal of Non-Crystalline Solids (2011), 357 (15), 2796-2801CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
      Aluminate glasses are important materials from a fundamental structural point of view because Al is the only network former. They present also a technol. interest because of their good IR transmission and ultralow optical losses. Aluminum in glasses of the system MO-Al2O3 (M = Ca, Sr, Ba) can have different coordination nos., essentially 4 and 6, as a function of the MO/Al2O3 ratio. Using Raman spectroscopy and high field 27Al NMR spectroscopy, we have detd. the structure of aluminum network as a function of MO/Al2O3 ratio with M corresponds to different alk.-earth cations. Al is essentially in 4-fold coordination with different amts. for Al2O3 between 50 and 75% but varies between Q2 and Q4 species as a function of MO/Al2O3 ratio where Q is tetrahedral species and n the no. of bridging oxygen.
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    52. 52
      Martínez-Ramírez, S.; Gutierrez-Contreras, R.; Husillos-Rodriguez, N.; Fernández-Carrasco, L. In-Situ Reaction of the Very Early Hydration of C3A-Gypsum-Sucrose System by Micro-Raman Spectroscopy. Cem. Concr. Compos. 2016, 73, 251– 256,  DOI: 10.1016/j.cemconcomp.2016.07.020
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      In-situ reaction of the very early hydration of C3A-gypsum-sucrose system by Micro-Raman spectroscopy
      Martinez-Ramirez, Sagrario; Gutierrez-Contreras, Rocio; Husillos-Rodriguez, Nuria; Fernandez-Carrasco, Lucia
      Cement & Concrete Composites (2016), 73 (), 251-256CODEN: CCOCEG; ISSN:0958-9465. (Elsevier Ltd.)
      This paper studied in situ, by Micro-Raman spectroscopy, the very early hydration of C3A in the presence and absence of sulfates and with sucrose as an additive. For C3A hydration in the absence of gypsum, when carbonation is not avoided, carbonate-AFm phases are formed, but in the presence of gypsum, hydroxi-AFm are the main phases. Ettringite is the AFm stable phase developed initially at 70 min of hydration with gypsum and no monosulfate is formed. In the presence of sucrose, this salt, instead of sulfate, is adsorbed over the surface of the C3A, avoiding its reaction with sulfates until sucrose desorption. Three hours are necessary to lead to ettringite formation. A nucleation poisoning/adsorption surface mechanism is proposed for added sucrose systems.
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      You, J.-L.; Jiang, G.-C.; Hou, H.-Y.; Chen, H.; Wu, Y.-Q.; Xu, K.-D. Quantum Chemistry Study on Superstructure and Raman Spectra of Binary Sodium Silicates. J. Raman Spectrosc. 2005, 36, 237– 249,  DOI: 10.1002/jrs.1287
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      Quantum chemistry study on superstructure and Raman spectra of binary sodium silicates
      You, J.-L.; Jiang, G.-C.; Hou, H.-Y.; Chen, H.; Wu, Y.-Q.; Xu, K.-D.
      Journal of Raman Spectroscopy (2005), 36 (3), 237-249CODEN: JRSPAF; ISSN:0377-0486. (John Wiley & Sons Ltd.)
      Raman spectra of binary sodium silicates in various components were calcd. by the SCF MO ab initio calcn. quantum chem. (QC) method with several polysilicon-oxygen tetrahedral model clusters with both 6-31G and 6-31G(d) basis sets being applied. Relevant pure anion clusters were also be calcd. to det. the cation effect by comparison with the available sodium series. High and intermediate Raman-active wavenumber ranges were esp. considered. The sym. stretching vibrational wavenumber of non-bridging oxygen (NBO) in the high-wavenumber range and its Raman scattering cross-section were deduced and analyzed. Several synthesized binary sodium silicate crystals were measured for comparison. The correlation between the vibrational Raman shift and the microscopic environment of the silicon-oxygen tetrahedron (SiOT) was found based on interior stress of configuration or superstructure, which depends on the connecting topol. of adjacent SiOTs. A newly established empirical stress index of a tetrahedron (SIT) was introduced to elucidate the above relationship. A new notation of SiOT accompanied by superstructure information was proposed and used to describe the practical and delicate types of SiOT in various states of binary sodium silicates. The Raman scattering cross-section of the sym. stretching vibration of NBO shows a roughly decreasing relationship with SIT or the Raman shift in the high-wavenumber range only under the circumstance of equiv. linkage between SiOTs, and Raman optical activity (ROA) enhancement of Q3 species occurs with Q4 species as its nearest neighbor, which indicates the electronic coupling between them. It was also demonstrated that the Si-Ob-Si bending vibrational Raman shift in the intermediate wavenumber range shows a monotonic decreasing relationship with the value of the Si-Ob-Si angle while other minor impacting factors remains unknown. This work offers basic information on the superstructure of binary sodium silicates and its relationship with characteristic vibrational Raman spectra, which can be widely applied in qual. and quant. studies of the microstructure of silicates.
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      Chryssikos, G. D.; Kamitsos, E. I.; Patsis, A. P. Effect of Li2SO4 on the Structure of Li2O─B2O3 Glasses. J. Non-Cryst. Solids 1996, 202, 222– 232,  DOI: 10.1016/0022-3093(96)00200-1
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      Effect of Li2SO4 on the structure of Li2O-B2O3 glasses
      Chryssikos, G. D.; Kamitsos, E. I.; Patsis, A. P.
      Journal of Non-Crystalline Solids (1996), 202 (3), 222-232CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier)
      IR reflectance and Raman spectroscopic measurements of xLi2SO4·(1-x)[RLi2O·B2O3] fast ionic conducting glass samples with R = 1 (metaborate), R = 2 (pyroborate) and 0≤x≤0.60 have been made. The SO42- ions of slightly distorted Td symmetry are found to occupy interstitial positions in the glass network and to decrease the basicity of the Li+-hosting sites. Increasing Li2SO4 content induces small structural changes to the depolymd. R = 2 glasses, but has a larger effect on the structure of the more covalently bonded R = 1 network. In this latter case, small addns. of Li2SO4, up to x≈0.05, induce the transformation of metaborate triangles into their isomeric tetrahedral species. Further increases of x lead to the reversal of this trend. The complex influence of Li2SO4 on the metaborate network is obsd. in the irregular shape of the Li2SO4-Li2O-B2O3 glass-forming range, as well as on the non-monotonic dependence of the activation energy for ion transport on x. The spectroscopic results are compatible with the formation of Li2SO4 microdomains at large Li2SO4 contents.
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      Black, L.; Breen, C.; Yarwood, J.; Deng, C. S.; Phipps, J.; Maitland, G. Hydration of Tricalcium Aluminate (C3A) in the Presence and Absence of Gypsum - Studied by Raman Spectroscopy and X-Ray Diffraction. J. Mater. Chem. 2006, 16, 1263– 1272,  DOI: 10.1039/b509904h
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      Hydration of tricalcium aluminate (C3A) in the presence and absence of gypsum-studied by Raman spectroscopy and X-ray diffraction
      Black, Leon; Breen, Chris; Yarwood, Jack; Deng, C.-S.; Phipps, Jonathan; Maitland, Geoff
      Journal of Materials Chemistry (2006), 16 (13), 1263-1272CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)
      Raman spectroscopy has been used to follow the hydration of one of the principal components of Ordinary Portland Cement (OPC) clinkers, tricalcium aluminate, both in the absence and in the presence of calcium sulfate. Direct in-situ anal. of the hydrating paste surface was possible. Spectra were recorded regularly during the first 24 h of hydration, and then systematically after hydration periods of up to 28 days. X-Ray diffraction was performed to confirm sample identity, firstly after 24 h and then regularly in coordination with Raman anal. Hydration in the absence of sulfate was rapid and led to the initial formation of C4AH19 and subsequently C3AH6. Characteristic changes were seen in the Raman spectra and the products' identities confirmed by XRD. Hydration in the presence of sulfate led to very rapid ettringite (AFt) formation, with the first evidence of ettringite formation within 3 min. Ettringite gradually converted to monosulfate (AFm), with the re-formation of traces of gypsum at high sulfate contents. Ettringite was formed at the expense of C4AH19. The level of C4AH19 formed diminished greatly with increasing sulfate content. Care was taken throughout the study to exclude carbon dioxide, thus minimizing formation of various carbonate species, which could also be readily distinguished by Raman spectroscopy. By combining the results obtained using the well-established technique of X-ray diffraction with Raman spectroscopy, in-situ characterization of hydrating pastes has been achieved in real-time. In addn. to demonstrating the suitability of Raman spectroscopy for anal. of these systems this study should aid the understanding of tricalcium aluminate hydration and the formation of ettringite and monosulfate.
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      Hu, Q.; Lei, L.; Jiang, X.; Feng, Z. C.; Tang, M.; He, D. Li Ion Diffusion in LiAlO2 Investigated by Raman Spectroscopy. Solid State Sci. 2014, 37, 103– 107,  DOI: 10.1016/J.SOLIDSTATESCIENCES.2014.08.017
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      Li ion diffusion in LiAlO2 investigated by Raman spectroscopy
      Hu, Qiwei; Lei, Li; Jiang, Xiaodong; Feng, Zhe Chuan; Tang, Mingjun; He, Duanwei
      Solid State Sciences (2014), 37 (), 103-107CODEN: SSSCFJ; ISSN:1293-2558. (Elsevier Masson SAS)
      The temp. dependence of Li ions behavior of γ-LiAlO2 has been studied from 78 to 873 K. On heating, the Li ions underwent positional disordering along the structural channels, with the Li ions related modes at 220, 366 and 400 cm-1 broadening and weakening dramatically. An anomalous max. in the bandwidths of the Li ions related modes is obsd. It should be apparent that there are at least two distinct thermally activated processes. A model suggested by Andrade and Porto is used to describe the linewidth of a phonon.
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      Remy, C.; Reynard, B.; Madon, M. Raman Spectroscopic Investigations of Dicalcium Silicate: Polymorphs and High-Temperature Phase Transformations. J. Am. Ceram. Soc. 1997, 80, 413– 423,  DOI: 10.1111/j.1151-2916.1997.tb02846.x
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      Raman spectroscopic investigations of dicalcium silicate: polymorphs and high-temperature phase transformations
      Remy, Corinne; Reynard, Bruno; Madon, Michel
      Journal of the American Ceramic Society (1997), 80 (2), 413-423CODEN: JACTAW; ISSN:0002-7820. (American Ceramic Society)
      Polymorphs and high-temp. phase transformations of dicalcium silicate (Ca2SiO4) are investigated on powd. samples, using Raman scattering techniques. Raman spectra at room conditions of pure γ- and β-Ca2SiO4 and stabilized β- α'L- and α-Ca2SiO4 are presented in the frequency range of 110-1100 cm-1. Each polymorph can be identified by its Raman spectrum, even though strong similarities exist between the β, α'L, and α phases. In-situ high-temp. Raman spectroscopic studies in the temp. range of 298-1433 K on heating and cooling also are reported, started from γ-Ca2SiO4. Modifications occurring in the Raman spectra recorded in the wavenumber. range of 90-1000 cm-1 show up during heating, the irreversible γ → α'L phase transformation. Coexistence of γ and α'L grains is obsd. in the temp. range of 1091-1119 K at least. The differences obsd. between the γ-Ca2SiO4 and α'L-Ca2SiO4 Raman spectra suggest that this phase transformation is a reconstructive first-order transition. The reversible α'L ↹ β phase transformation also is described. Raman spectra of pure β and α'L phases resemble each other. The transition occurs from 949 K, on cooling, to 960-988 K, on heating, with a hysteresis probably dependent on the thermal history of the starting product. From the Raman scattering observations, this phase transformation also is considered as a first-order transformation and is probably of a displacive type.
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      Mysen, B. O.; Finger, L. W.; Virgo, D.; Seifert, F. A. Curve-Fitting of Raman Spectra of Silicate Glasses. Am. Mineral. 1982, 67, 686
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      Curve-fitting of Raman spectra of silicate glasses
      Mysen, Bjoern O.; Finger, Larry W.; Virgo, David; Seifert, Friedrich A.
      American Mineralogist (1982), 67 (7-8), 686-95CODEN: AMMIAY; ISSN:0003-004X.
      A procedure for deconvolution of complex Raman spectra of amorphous materials (e.g. silicate glass and melt) is described. The line shapes and quality of the fits are detd. statistically after correction for the temp.- and frequency-dependence of the Raman intensities. In the fitting routine, intensity, half-width, and position (frequency) of all bands are treated simultaneously as unconstrained variables. The no. of lines fitted to a spectrum is also treated statistically by numerical minimization of the squares of the deviations between the obsd. and the calcd. Raman envelopes and by maximizing the randomness of the residuals. It is assumed, however, that all bands are sym.
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      Kang, J.; Wang, J.; Zhou, X.; Yuan, J.; Hou, Y.; Qian, S.; Li, S.; Yue, Y. Effects of Alkali Metal Oxides on Crystallization Behavior and Acid Corrosion Resistance of Cordierite-Based Glass-Ceramics. J. Non-Cryst. Solids 2018, 481, 184– 190,  DOI: 10.1016/j.jnoncrysol.2017.10.048
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      Effects of alkali metal oxides on crystallization behavior and acid corrosion resistance of cordierite-based glass-ceramics
      Kang, Junfeng; Wang, Jing; Zhou, Xinyan; Yuan, Jian; Hou, Yansheng; Qian, Shaoyang; Li, Sheng; Yue, Yunlong
      Journal of Non-Crystalline Solids (2018), 481 (), 184-190CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)
      MgO-Al2O3-SiO2-TiO2 glass-ceramics with 3 mol% alkali metal oxides were prepd., and the 3 mol% alkali metal oxides were induced by 3 mol% Na2O only, 1.5 mol% Na2O + 1.5 mol% Li2O, and 1.5 mol% Na2O + 1.5 mol% K2O, resp. Effects of alkali metal oxides on the crystn. behavior and acid corrosion resistance of the MgO-Al2O3-SiO2-TiO2 glass-ceramics were investigated. μ-Cordierite pptd. in the glass matrix firstly, and it changed into α-cordierite with the crystn. temp. increasing. Using K2O substitution of Na2O hindered the pptn. of cordierite, while the addn. of Li2O promoted the pptn. of μ-cordierite at low temps. When the main cryst. phase was μ-cordierite, the acid resistance of the glass-ceramics was significantly improved compared with the base glass. With the main cryst. phase changing from μ-cordierite to α-cordierite, the acid resistance of the glass-ceramics became worse, which was related to the honeycomb structure of α-cordierite. When 1.5 mol% Na2O was replaced by Li2O, the glass samples crystd. at 880° showed the optimum acid resistance with the min. wt. loss ∼0.096%.
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