New interpretation of activation enthalpies for electrical conductivity and nuclear spin relaxation in glassy ionic conductors

Abstract

Experimental data of nuclear spin relaxation by two-level systems in alkali silicate, borate, and germanate glasses from 3\ensuremath{\le}T\ensuremath{\le}700 K can be described in terms of a microscopic energy barrier impeding ion motion which is significantly different from the activation energy of ionic conductivity. This description can be understood in terms of the coupling model of conductivity relaxation in glassy ionic conductors.