Standard transition aluminas. Electron microscopy studies

Abstract

The aim of this paper is to present the results of characterization of the particle shapes of six standard transition aluminas samples using transmission and scanning electron microscopies; selected area electron diffraction, in parallel with X-ray powder diffraction were used for confirmation of the different transition aluminas types. The transition aluminas - chi; kappa; gamma; theta; delta; and eta were supplied by ALCOA Central Laboratory. The chi-; kappa-;gamma- and delta-Al(2)0(3) microcrystals are pseudomorphs from their respective precursors gibbsite and boehmite. However, theta-Al(2)0(3) microcrystals are not pseudomorphs after the standard delta-Al(2)0(3) sample. Also, eta-Al(2)0(3) are not pseudomorphs after bayerite somatoids.

Keywords

• transition aluminas
• alumina precursors
• gibbsite
• electron microscopies