Effect of crystallite size on the thermal phase change and porous properties of boehmite.
The effect of crystallite size on the thermal phase change and porous properties of boehmite was investigated using boehmites with crystallite sizes of 2.9 to 24.4 nm and boehmite gels prepared by precipitation and hydrothermal methods. The dehydroxylation temperature of boehmite increases, its phase transition temperature from gamma- to theta-Al(2)O(3) decreases and the theta- to alpha-Al(2)O(3) transition temperature increases as the crystallite size of the boehmite increases. Boehmite with a crystallite size of approximately 5 nm shows the highest specific surface area and greatest thermal stability. This boehmite contains pores of about 2-3 nm radius, suggested to be responsible for the superior porous properties and thermal stability.
Okada
Kiyoshi
K
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, O-okayama Meguro, Tokyo, 152-8552, Japan. kokada@o.cc.titech.ac.jp
Nagashima
Toru
T
Kameshima
Yoshikazu
Y
Yasumori
Atsuo
A
D000536:Aluminum Hydroxide / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D003460:Crystallization; D005782:Gels / Q000737:chemistry; D010316:Particle Size; D044367:Phase Transition; D016062:Porosity; D013499:Surface Properties; D013696:Temperature
D005782:Gels; D000536:Aluminum Hydroxide; C069471:aluminum oxide hydroxide; D000537:Aluminum Oxide