Effect Of Fe203 As A Dopant In The Transformation Of A-Al2O3 From Activated Gibbsite On The Nanocrystalline A-Al2O3 Preparation

The effect of iron oxide in the transformation of a-Al2O3 from activated gibbsite was studied with the addition of 4 weight % Fe2O3 of the aluminia. Nanocrystalline a-Al2O3 was prepared using gibbsite (Al(OH)3), sulphuric acid, iron (II) suphate, and sugar through chemical and physical routed. In the process, (Al(OH)3 reacted with sulphuric acid to form boehmite, whereas 4 weight % FeSO4 and sugar were added as dopants and as a masking agent, respectively. The mixture was heated at 200 degrees C and then was calcined at different temperatures ranging from 500 degress C to 1000 degrees C for 5 h in an air atmosphere. The addition of 4 weight % Fe2O3 lowered the transformation temperature of a-Al2O3 at 500 degrees C-900 degrees C. XRD analysis identified a-Al2O3 crystal planes of (102), (104), (113) and (106) at 500 degrees C, having crystalline sizes from 4 to 6nm. The transformation to a-Al2O3 completely occurred at 900 degrees C. As a comparison, a-Al2O3 was also prepared from activated gibbsite with sulphuric acid and pure gibbsite. The calcination was conducted at 1000 degrees C for the last two compositions. However, activated gibbsite produced several transition aluminias such as y-Al2O3, k-Al2O3 and a-Al2O3 at 1000 degrees C; whereas pure gibbsite transformed k-Al2O3 and a-Al2O3 at the same temperature. Nevertheless, the goal of this study is to prepare iron oxide doped a-Al2O3 as a starting material for structural applications.