Dynamics of the glass and superionic phase transitions in Cs₅H₃(SO₄)₄·H₂O protonic conductor

Abstract

Abstract IR, Raman and Brillouin spectra of the fast protonic conductor Cs5H3(SO4)4 · xH2O (x ≤ 1) have been investigated in the 80-500 K (IR), 20-435 K (Raman) and 190-425 K (Brillouin) temperature range. Results of the DSC analysis are presented, which reveal a hysteresis of both the superionic and glass transition temperature. The spectra are interpreted on the basis of a factor-group analysis; the mechanism of the proton glass transition and that of the proton transport in the superionic phase are discussed. Brillouin spectra revealed a relaxation process with the frequency 1.25 × 1010 Hz at 274 K which differs from that observed in dielectric data. The former relaxation is assigned to SO4 2 reorientations, the latter to slower interbond proton hopping.