Ionic Conductivity of Li ₄ SiO ₄ , Li ₄ GeO ₄ , and Their Solid Solutions

Abstract

Conductivity was measured for Li 4 SiO 4 and its solid solutions with Li 4 GeO 4 over a wide frequency range to separate clearly the effects of electrode polarization, conductance relaxations, etc., and to obtain true “dc” conductivities. The conductivities of all the electrolytes are markedly temperature‐dependent, ranging from 10 −8 to 10 −10 Ω −1 cm −1 at 100°C to 10 −2 to 10 10 Ω −1 cm −1 at 700°C. For solid solutions with the Li 4 GeO 4 structure, conductivities fit the Arrhenius equation over a wide temperature range, but at higher temperatures a change in activation energy occurs, corresponding to a first‐order phase transition. In contrast, solid solutions with the Li 4 SiO 4 structure show changes in activation energy which do not correspond to phase transitions, but which appear to indicate changes in the conduction mechanism.