LOW-TEMPERATURE DIELECTRIC SUSCEPTIBILITY OF LI, NA, K, AND AG BETA-ALUMINA

Crystalline Na, K, Li, and Ag alumina show glasslike variations of the dielectric susceptibility with temperature and frequency provided the measuring field is directed along the conducting planes. Only Li alumina shows variations of the dielectric susceptibility perpendicular to the conducting planes. The data are discussed in terms of the tunneling-states model of amorphous materials. The estimated average tunneling distances are 0.3. © 1979 The American Physical Society.