Study on the structure, phase transition and electrical conductivity of cadmium-doped Bi₂VO_5.5

The structure, phase transition and electrical conductivity of the fast ion conducting system BICDVOX, cadmium-doped Bi₂VO_5.5, were investigated by using X-ray powder diffraction, DSC, and Ac impedance spectroscopy. Two models, Bi₂V_1-xCd_x O_5.5-3/2x (x=0.05, 0.075, 0.10, 0.125, 0.15) and Bi_2-xVCd_xO_5.5-1/2x (x=0.10, 0.20), were given to synthesize these materials, due to the size of the ion radius of cadmium being close to that of vanadium and bismuth. The results of XRD and DSC show the two models maybe all exist. When x=0.10 the composition of the first model was found to have higher ionic conductivity by ac impedance spectroscopy, which is attributed to the stabilized tetragonal phase.