Anomalous temperature dependence of conductivity and X-ray diffraction in Cu_xPb_1−xBr_2−x solid solution

Abstract

The temperature dependence of the electrical impedance of Cu_xPb_1−xBr_2−x was measured. Both conductivity and relaxation time of ion migration at two temperature regions above and below 145 °C showed anomalous differences. Intensity measurements of X-ray diffraction were also carried out varying the temperature over the range from 30 to 200 °C. The integrated intensity for Bragg reflection abruptly decreased above 145 °C with increasing temperature. We obtained a mean square displacement of atoms, resulting from a Debye-Waller factor. It is therefore concluded that the anomalous temperature dependence of the conductivity above 145 °C is due to anharmonic vibration of the Cu atom.