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Low-temperature ion conductivity of RbAg4I5

1990; Elsevier BV; Volume: 285; Issue: 1-2 Linguagem: Inglês

10.1016/0022-0728(90)87124-3

2590-2954

A. Pinkowski, T. Chierchie, W.J. Lorenz,

Glass properties and applications

The specific ionic conductivity, σ, of the solid electrolyte RbAg4I5 was determined by four-probe impedance measurements in the temperature range 28 ⩽ T⩽ 299 K. Good agreement was obtained with previous two-probe σ data at temperatures above the β-γ phase transition temperature Tβ-γ = 121.75 K. Between Tβ-γ and about T = 109±1 K, a decrease of σ by 2–3 orders of magnitude occurred. At T ⩽ 109 K, a distinct change in the activation energy of σ was observed with almost temperature-independent mobility of the conducting Ag+ ions in this low temperature range. This behaviour is explained by a possible glass-like transition occurring at Tg ≈ 109 K, and a barrierless tunnelling mechanism via TLS states (two-level tunnelling system) below Tg. The implications of the low-temperature conductivity of solid electrolytes for electrochemical studies in this temperature range are discussed.