Ionic Conduction and Water Diffusion in Li beta -Alumina

摘要

Lithium beta -alumina is one of a family of compounds that have exceptionally high ionic conductivities. Partly as a consequence of the small size of the Li exp + ion, the properties of Li beta -alumina such as structure and conductivity are exceptions to the trends set by other alkali-metal beta -aluminas. Both Li and Na beta -alumina absorb water molecules into their conduction layers, but the hydration rate of Li beta -alumina is much higher. In this paper we review and analyze these properties of Li beta -alumina. Some of the analysis is based on the results of potential energy calculations. In particular, the interstitialcy conduction mechanism responsible for the high ionic conductivity in Na beta -alumina is found to be applicable in Li beta -alumina, but the conduction path is modified. The rapid diffusion of H sub 2 O in Li beta -alumina is attributed to the tendency of water molecules to dissociate in the material. 12 figures. (ERA citation 10:018818)