Evidence for breaking of the center of symmetry in zero-dimensional H-bonded quantum paraelectric Rb3H(SeO4)2

• Published in: Solid state communications 2000-07, Vol.115 (9), p.473-476
• Main Authors: GUSTAFSSON, T, ICHIKAWA, M, OLOVSSON, I
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Elements, oxides, nitrides, borides, carbides, chalcogenides, etc; Exact sciences and technology; Inorganic compounds; Physics; Salts; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0038-1098; 1879-2766; 1879-2766
• DOI: 10.1016/S0038-1098(00)00227-1

We show by means of single-crystal neutron-scattering that the space group of the quantum paraelectric Rb3H(SeO4)2 is not centrosymmetric A2/a as accepted so far, but noncentrosymmetric A2. The intensities of the reflections forbidden for the space group A2/a, (h 0 l): h≠2n, decrease with decreasing temperature. The refinement of the structure gave a systematically smaller discrepancy values in A2 than in A2/a. This makes it necessary to modify the commonly accepted fact that the space group is A2/a for most members of M3H(XO4)2-type crystals. The symmetry breaking is mainly due to the atoms directly connected to the O–H⋯O hydrogen-bond system, other parts being substantially unchanged. The possible origin of the temperature dependence of the intensities of the symmetry-breaking reflections is discussed.