COMPARISONS BETWEEN NA-23 AND AL-27 NUCLEAR-SPIN RELAXATIONS AND ELECTRICAL-CONDUCTIVITY RELAXATION IN NA BETA-ALUMINA

Recently several groups have found pronounced differences between mobile ion nuclear spin relaxation (NSR) and electrical conductivity relaxation (ECR) in a number of superionic glasses, and the absence of such pronounced differences if the nuclear spin probed is not that of a mobile ion but one that is tied down to the glassy matrix. By now it is well known that Na beta-Al2O3 though not a superionic glass behaves in many ways like one. Measurements on the Na-23 and Al-27 nuclear relaxation times in Na beta-Al2O3 are compared with electrical conductivity relaxation to show that there is a pronounced difference between Na-23 NSR and ECR and a lack of it between Al-27 NSR and ECR. Thus, these newly discovered properties of superionic glasses carry over to Na beta-Al2O3. Like in superionic glasses, all aspects of NSR and ECR experimental data of Na betaAl2O3 have been explained by the coupling model.