The dispersion of the complex dielectric permittivity of Bi2Co0.1V0.9O5.35 was investigated at temperatures of between 300 and 800K, using frequencies ranging from 1 to 100MHz. An observed relaxation process was attributed to a diffusional polarization which was associated with short-range jumps of O vacancies in the lattice. A determination of the conductivity and of the relaxation frequency permitted an estimate to be made of the diffusion coefficient of O vacancies, as well as of their concentration. Good agreement was found between the activation energy for ionic conductivity and the activation energy of the relaxation frequency. It was concluded that the estimated concentration of mobile O vacancies did not change with temperature, and was approximately equal to the concentration of O vacancies as determined by a refinement of the crystal structure of the high-temperature disordered γ' phase. The Raman scattering of the samples was also investigated. A maximum scattering which was found at around 155 and 240/cm was suggested to correspond to the attempt frequency of the mobile O ions.

Relaxation Dispersion of Ionic Conductivity of BICOVOX. A.Kezionis, W.Bogusz, F.Krok, J.Dygas, A.Orliukas, I.Abrahams, W.Gebicki: Solid State Ionics, 1999, 119[1-4], 145-50