Dielectric and impedance spectroscopy of (Bi0.5Li0.5)(Fe0.5Nb0.5)O3 multiferroics

The polycrystalline sample of (Bi0.5Li0.5)(Fe0.5Nb0.5)O-3 was prepared by a solid-state reaction method. Preliminary X-ray structural analysis of the sample suggests the formation of a tetragonal phase with a new unit cell configuration. Dielectric, electrical, impedance and modulus properties of the material were investigated in a wide range of temperature (25-500 degrees C) and frequency (1kHz-1MHz). Two dielectric anomalies observed at 295 degrees C and 400 degrees C clearly suggest the existence of magnetic phase transition and two relaxation processes in the system. Dielectric properties have greatly been improved on addition of LiNbO3 to BiFeO3. The appearance of a hysteresis loop at room temperature confirms the ferroelectric properties of the material. The nature of the Nyquist plot confirms the presence of both bulk and grain boundary effects in the material. The ac conductivity was found to obey Jonscher's power law. The dc conductivity variation with temperature follows the Arrhenius equation. The induced voltage changes with the applied magnetic field, showing that the sample is multiferroic.