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 unsing transmission and scanning electron microscopies; selected area electron diffraction, in parallel with X-ray 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 Al2O3 microcrystals are pseudomorphs from their respective precursors gibbsite and bohemite. However, theta-Al2O3 microcrystal are not pseudomorphs after the standard delta-Al2O3 sample. Also, eta-Al2O3 are not pseudomorphs after bayerite somatoids.