Structural and conductivity studies of CsKSO4Te(OH)6 and Rb1.25K0.75SO4Te(OH)6 materials

The crystal structures of the title compounds were solved using the single-crystal X-ray diffraction technique. At room temperature CsKSO4Te(OH)6 was found to crystallize in the monoclinic system with Pn   space group and lattice parameters: a=12.5463(6)Å; b=6.5765(2)Å; c=12.6916(7)Å; β=106.53(2)°β=106.53(2)°; V=1003.914(4)Å3; Z=4Z=4 and Dcalc.=3.29g/cm3. The structural refinement has led to a reliability factor of R1=0.0284R1=0.0284 (wR2=0.064wR2=0.064) for 7577 independent reflections. Rb1.25K0.75SO4Te(OH)6 material possesses a monoclinic structure with space group P21/a   and cell parameters: a=11.3411(6)Å; b=6.5819(2)Å; c=13.5730(8)Å; β=106.860(10)°β=106.860(10)°; V=969.62(10)Å3; Z=4Z=4 and D=3.16(3)g/cm3. The residuals are R1=0.0297R1=0.0297 and wR2=0.0776wR2=0.0776 for 3336 independent reflections. The main interest of these structures is the presence of two different and independent anionic groups (TeO66− and SO42−) in the same crystal.Complex impedance measurements (Z*=Z′—iZ″Z*=Z′—iZ″) have been undertaken in the frequency and temperature ranges 20–106 Hz and 400–600 K, respectively. The dielectric relaxation is studied in the complex modulus formalism M*M*.

Projection of CsK(SO4)·Te(OH)6 crystal structure on the ac plane.Figure optionsDownload as PowerPoint slide