Abstract
BiFe1-xNixO3 (x = 0.7, 0.8 and 0.9) polycrystalline ceramics are synthesized by a solid-state reaction, and their structural, absorption, leakage current and electrical properties are investigated. The X-ray diffraction measurements show that the lattice parameter values increase with increasing the substitution of Ni2+ ions for Fe3+ ions. The optical absorption spectra indicate that the band gap energy increases with increasing Ni2+ ions. Leakage currents are much decreased by about three orders of magnitude with increasing Ni ions. The J-E hysteresis was also investigated. Both real and imaginary dielectric constants are investigated as a function of both frequency and temperature. The room temperature dielectric measurement with a wide frequency range of 1 KHz-1 MHz reveals that the real and imaginary dielectric constants are decreased with increasing frequency of BiFe1-xNixO3 (x = 0.7, 0.8, 0.9) ceramics. The real and imaginary dielectric constants are found to be increased with temperature. The temperature dependence of epsilon ' and epsilon '' exhibits an anomaly which shifted to lower temperature with increasing Ni2+. The anomaly indicates the possible existence of spin-glass states with Ni2+ ion substitution in places of Fe3+ ions.