On-line version ISSN 1980-5373
SANTOS, P. Souza; SANTOS, H. Souza and TOLEDO, S.P.. Standard transition aluminas. Electron microscopy studies. Mat. Res. [online]. 2000, vol.3, n.4, pp. 104-114. ISSN 1980-5373. http://dx.doi.org/10.1590/S1516-14392000000400003.
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-Al203 microcrystals are pseudomorphs from their respective precursors gibbsite and boehmite. However, theta-Al203 microcrystals are not pseudomorphs after the standard delta-Al203 sample. Also, eta-Al203 are not pseudomorphs after bayerite somatoids.
Keywords : transition aluminas; alumina precursors; gibbsite; electron microscopies.