Irradiation-induced defects in β''- and β''''-alumina examined by 1 MV high-resolution electron microscopy

During transmission electron microscope observations of the rhombohedral β''- and β''''-alumina, structural changes due to the loss of some conduction planes takes place as an electron irradiation effect, while the hexagonal counterparts β- and β'''-alumina are relatively stable. Based on the structures of electron-induced defects determined from high-resolution 1 MV EM images, phenomena are interpreted in terms of the characteristic crystal structures of β''- and β''''-alumina. The results are discussed in connection with the problem of degradation of β''-alumina solid electrolytes used in the Na-S battery system. (Auth.)