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Article

A Thermodynamically Stable Nanophase Material

Supporting Info

Zhang Lin,^† Benjamin Gilbert,^‡ Quanlin Liu,^§ Guoqiang Ren,^† and Feng Huang*^†

Contribution from the Laboratory of Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, National Engineering Research Center for Optoelectronic Crystalline Materials, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, People's Republic of China, Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083, People's Republic of China

J. Am. Chem. Soc., 2006, 128 (18), pp 6126–6131

DOI: 10.1021/ja057121p

Publication Date (Web): April 18, 2006

†

Chinese Academy of Sciences.

‡

Lawrence Berkeley National Laboratory.

University of Science and Technology Beijing.

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, fhuang@fjirsm.ac.cn

Abstract

Nanoparticles are metastable relative to the equivalent bulk material due to the positive excess interfacial free energy (IFE). Previous studies have shown that, with increasing surface interaction strength, the IFE diminishes but remains positive. We describe an experimental multicomponent system in which a nanoscale ZnS material is thermodynamically favored and can be formed at the expense of bulk ZnS. In 17 M sodium hydroxide solution, at 230 °C, both 3 nm ZnS nanoparticles and bulk ZnS are transformed into sheetlike nanocrystals with a ZnS polytype structure. Our results are theoretically compatible with the concept of a negative IFE, although not with the assumption of constant interface composition. We clarify the meaning of an effective negative IFE and present the necessary conditions for strong chemical surface interactions to stabilize nanoscale inorganic materials relative to bulk matter. Our results show that synthesis methods employing thermodynamic controls can produce nanomaterials with novel morphology.

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