Abstract

The crystalline aluminium hydroxide boehmite is the most important precursor of the alumina used for the production of "actives aluminas". Differences in the degree of order in the crystalline structure may produce a significant difference in the crystal shape: fibrillar pseudo-boehmite and lath-like hexagonal well-order boehmite are examples. The paper reviews that structure of the transition aluminas former from several aluminium compounds and in detail the morphological changes and differences in crystal shapes of the transition aluminas formed from thermal transformation up to 1500°C by MET, SAED and XRD.