A diffuse X-ray scattering study of the fast-ion conductors barium beta" alumina and lead beta" alumina

The authors have carried out diffuse X-ray scattering studies of barium beta" alumina (Ba beta ") and lead beta" alumina (Pb beta ") in the temperature range 25 to 973 K. Double- and triple-axis diffractometry provided medium-to-high momentum resolution. They conclude that in Ba beta " there is a local preferential condensation of Ba2+ ions onto one of the two 6c sublattices. In Pb beta " the data indicate clustering of the Pb2+ions and simultaneously there is some degree of local sublattice condensation. The authors also find evidence for inter-planar correlations of the conducting ions Ba2+ and Pb2+, persisting in Ba beta " up to 600 degrees C and in Pb beta " to 300 degrees C. They suggest that the configurations they have investigated are metastable in nature and that more ordered configurations are possible.