Synthesis of nanocrystalline α-Al <inf>2</inf>O <inf>3</inf> from nanocrystalline boehmite derived from high energy ball milling of gibbiste

Dry milling of gibbsite has been carried out for 5 h in planetary ball mill to study the effect of mechanical activation on α-Al 2O 3 formation. Gibbsite undergoes phase transformation during milling and has resulted nanocrystalline boehmite after 5 h of milling. The average crystallite size and the BET surface area of the nanocrystalline boehmite resulted by 5 h milling of gibbsite are 8 nm and 140 m 2/g, respectively. The nanocrystalline boehmite has shown reduction in the α-Al 2O 3 formation temperature as well as in the activation energy of α-Al 2O 3 formation. The average crystallite size of nanocrystalline boehmite derived α-Al 2O 3 is measured to be 100 nm by TEM analysis and the BET surface area of resulted nanocrystalline α-Al 2O 3 is 12 m 2/g. © 2011 Indian Institute of Metals.