Crystal Structures and Electron Induced Damage in β-Alumina Related Compounds

Abstract

During the transmission electron microscope observations of β''- and β''''-alumina with rhombohedral symmetry, electron damage due to the loss of the conduction planes takes place to form the defect blocks ; whereas the hexagonal counterparts, β- and β'''-alumina are relatively stable. Based on the structure images taken by a high-resolution 1 MeV electron microscope, new structure models of the defect blocks are proposed in place of the previous two models which were mutually incompatible. The results are discussed in terms of the differences in the crystal-chemical characteristics between the rhombohedral and the hexagonal groups of compounds.