Web Release Date: October 26,
Preparation and Formation Mechanism of Alumina Hollow Nanospheres via High-Speed Jet Flame Combustion
and
Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science & Technology, Shanghai 200237, China, and School of Materials Science and Engineering, NanYang Technological University, Blk N4.1, NanYang Avenue, Singapore 639798, Singapore
Received for review March 28, 2007
Revised manuscript received September 9, 2007
Accepted September 11, 2007
Abstract:
A simple and effective method for the preparation of hollow alumina nanospheres was established via a
high-speed jet flame combustion process. The morphology and structure of the hollow nanospheres were
investigated using TEM, HRTEM, SEM, FTIR, XRD, BET, etc. A vapors mixture of C2H5OH and AlCl3
was exhausted at high speed into a flame reactor at 150 m/s and condensed into mesoscale droplets due to
the Joule-Thomson cooling effect and the entrainment of cool gases into the expanding high-speed jet. The
hollow alumina nanospheres were formed after the hydrolysis of AlCl3 in the H2/air flame at about 1200 
C.
The hollow alumina nanosphere was composed of nanocrystallites about 5 nm and the shell thickness was
10-30 nm. The formation mechanism of the hollow alumina nanospheres was investigated, conforming to
the one-droplet-to-one-particle theory.
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