BICUVOF: a new copper fluoride doped BIMEVOX

The relationship between conductivity and structure has been investigated in a new CuF2 substituted BIMEVOX, Bi2V1−xCuxO5.5−5x/2F2x, 0.10 ≤x≤ 0.20 (BICUVOF). The system has been characterised by X-ray powder diffraction and ac impedance spectroscopy. BICUVOF samples, in the compositional range studied, all show the tetragonal γ-phase structure when quenched from high temperature, however, there is evidence in the conductivity data of phase transitions associated with ordering phenomena at various temperatures. A large drop in conductivity is observed on solid solution formation. These observations are consistent with a mixed anion effect analogous to the mixed ion effect seen in cation conducting systems.