Superprotonic high temperature phase and refinement of the low temperature structure of CsHSeO4

Abstract

Abstract The crystal structure of the high temperature superprotonic phase of CsHSeO4-I (tI28) has been investigated by single crystal X-ray diffraction at 408 K. It crystallizes tetragonal, a = 5.880(1), c = 14.415(3) Å, V = 498.4(2) Å3, Z = 4, space group I41/amd. In the SeO4 tetrahedron, the Se-O distance is 1.66 Å after correction for libration. A layer-like hydrogen bonding system is suggested. The low temperature structure, CsHSeO4-II(mP28), was refined from X-ray diffraction data with an accuracy which made it possible to localize the H atom. Crystallographic relations between the two phases during the phase transition are discussed.