Molecular dynamics in (NH4)3H(SeO4)2 at superionic phase transitions: Raman spectroscopy study

Author: Wolak J.   Pawlowski A.   Polomska M.   Pietraszko A.  

Publisher: Taylor & Francis Ltd

ISSN: 0141-1594

Source: Phase Transitions: A Multinational Journal, Vol.86, Iss.2-3, 2013-02, pp. : 182-190

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Abstract

This article presents detailed temperature Raman spectra changes at two superprotonic phase transitions of (NH4)3H(SeO4)2. The study of temperature evolution of Raman spectra has shown great changes at low temperature phase transitions at T 3 and T 4, whereas only very small changes have been observed at the two superionic transformations at T 1S and T 2S. The stretching vibration frequencies of proton donor and acceptor selenate tetrahedra have been found to change slightly in the temperature range 295–341 K with a slope change at T 1S and T 2S. A slope change in temperature dependence of proton conductivity has also been observed at the same temperatures.