Structural and conductivity study of a new protonic conductor Cs0.86(NH4)1.14SO4·Te(OH)6

The crystal structure of Cs0.86(NH4)1.14SO4·Te(OH)6 is determined by X-ray diffraction analysis. The space group is P21/cP21/c with a=13.681(3)Å, b=6.608(1)Å, c=11.362(2)Å, β=106.65(3)°β=106.65(3)° and Z=4Z=4 at 293 K. The structure is refined to R=2.9%R=2.9%. The distribution of atoms can be described as isolated TeO6 octahedra and SO4 tetrahedra. The Cs+ and NH4+ cations, occupying the same positions, are located between these polyhedra. The main feature of this structure is the coexistence of two types of anions in the same crystal related by network hydrogen bonds.The mixed solid solution cesium ammonium sulphate tellurate exhibits two phase transitions at 470 and 500 K. These transitions, detected by differential scanning calorimetric, are analyzed by dielectric measurements using the impedance and modulus spectroscopy techniques.

Projection of Cs0.86(NH4)1.14SO4·Te(OH)6 crystal structure at 293 K on the ac plane.Figure optionsDownload as PowerPoint slide