Lithium and potassium ion conduction in A3TiB′P3O12 (A=Li, K; B′=Zn, Cd) NASICON-type glasses

Electrical properties of A3TiB′P3O12 (A=Li, K; B′=Zn, Cd) NASICON-type glasses are reported over a frequency range from 42 Hz to 1 MHz and at different temperatures. By means of nonlinear least square fitting of the electrical data to appropriate equivalent circuits, the bulk conductivity is separated from electrode effects. The bulk dc conductivity is Arrhenius activated, with activation energies and pre-exponential factors following the Meyer-Neldel rule. The frequency- and temperature-dependent conductivity spectra of individual glasses can be superimposed by means of the Summerfield scaling. However, the master curves of different glasses do not superimpose. We show that this effect is related to the composition dependence of the many-particle displacement function 〈R2(t)〉.