Anharmonic effective pair potentials of and CuBr at high pressure

Yoshiasa, Akira*; Okube, Maki*; Otaka, Osamu*; Kamishima, Osamu*; Katayama, Yoshinori

The anharmonic effective pair potentials for Br-Cu bond in and CuBr under pressure have been investigated by an extended X-ray absorption fine structure (EXAFS) technique. The EXAFS spectra near the Br K-edge were measured under high temperature and high pressure using a large-volume uniaxial press and synchrotron radiation from SPring-8. The anharmonic effective pair potential for each phase is influenced by pressure and become steeper with increasing pressure. The potential parameter for -phase at 0.1MPa increases by about 20% at the pressure of 4.8GPa. The stastical distribution of Cu in -CuBr and superionic conduction mechanism have been discussed based on the effective pair potential and distribution of Br-Cu distances.