Effect of Rare-Earth Doping on the Structural and Electrical Properties of BiFeO3 Submicron Particles

We report structural, electrical and impedance analysis of Bi0.95R0.05FeO3 submicron particles (R = Y, Ho, and Er). The compounds were synthesized by the sol-gel method. The compounds crystallized in a rhombohedral structure with R3c space group symmetry. The frequency-dependent real part of the impedance (Z') confirms the dielectric relaxation mechanisms, whereas the temperature dependence of Z' indicates the enhancement in conductivity of the samples with increasing temperature. The frequency dependent imaginary part of the impedance (Z '') exhibits a peak which is shifted to the higher frequency region with increasing temperature. This behaviour could be due to the reduction in relaxation time. Our analysis indicates that the conduction mechanism in pure and doped BiFeO3 sample is due to the oxygen vacancies. The motion of oxygen vacancies is blocked and their numbers are reduced upon rare-earth doping. The singly ionized oxygen vacancies and the doubly ionized oxygen vacancies are responsible for the low and high temperature conduction mechanisms, respectively.