Comparisons between 23Na and 27Al nuclear spin relaxations and electrical conductivity relaxation in Na β-alumina

Abstract

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 β-Al 2O 3 though not a superionic glass behaves in many ways like one. Measurements on the 23Na and 27Al nuclear relaxation times in Na β-Al 2O 3 are compared with electrical conductivity relaxation to show that there is a pronounced difference between 23Na NSR and ECR and a lack of it between 27Al NSR and ECR. Thus, these newly discovered properties of superionic glasses carry over to Na β-Al 2O 3. Like in superionic glasses, all aspects of NSR and ECR experimental data of Na β-Al 2O 3 have been explained by the coupling model.