Hypersonic wave anomalies in Cs3H(SeO4)2 at the transitions above room temperature
Centre de Recherche sur les Matériaux à Haute Température, CNRS, 1D avenue de la
Recherche Scientifique, 45071 Orléans Cedex 2, France
Corresponding author: a Yves.Luspin@univ-orleans.fr
Published online: 15 July 1999
The elastic properties of Cs3H(SeO4)2 are investigated by Brillouin spectroscopy in the temperature range 20-220,°C covering the two transitions III → II and II → I occurring at ~95°C and ~, respectively. Phase I is known to be a protonic conductive one. Discontinuities of elastic constants are generally observed at both transitions, implying first orderness. In phases II and I, a slight broadening of the Brillouin lines is detected. The results are discussed in comparison with compounds of the families XHSeO4 (X = NH4, Rb and Cs) and CsH2BO4 (B = As and P) which also undergo a transition to a superionic phase. In the conductive phase, it appears that the lattice anharmonicity is weaker in Cs3H(SeO4)2 than in these other compounds.
PACS: 64.70.Kb – Solid-solid transitions / 62.20.Dc – Elasticity, elastic constants / 78.35.+c – Brillouin and Rayleigh scattering; other light scattering
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999