High dielectric permittivity and room temperature magneto-dielectric response of charge disproportionate La0.5Ba0.5FeO3 perovskite

A charge disproportionate La0.5Ba0.5FeO3 (LBFO) ceramic sample with cubic structure has been synthesized by the conventional high-temperature solid-state reaction route. Dielectric behaviour of LBFO has been studied over a wide temperature (100-370 K) and frequency (100 Hz-5 MHz) ranges. LBFO exhibits relatively high dielectric permittivity (epsilon(r) similar to 5 x 10(3)) around room temperature and very weak temperature-and frequency-dependent behaviour over the mentioned ranges. Another interesting feature of LBFO is the appearance of room temperature magneto-dielectric response (magneto-dielectric similar to 7%) even at low magnetic field similar to 0.5 T. The combined complex impedance and modulus spectroscopic studies exhibit two relaxation processes corresponding to grain and grain boundary contributions with activation energies similar to 0.20 (for grain boundaries) and similar to 0.14 eV (for grains), respectively. The high er value of this electrically inhomogeneous sample with differently conducting grains and grain boundaries could be explained considering the Maxwell-Wagner-type interfacial polarization model. Magnetic field-dependent non-ferroelectric high dielectric behaviour of LBFO might be important for its applications in devices.