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 (εr ∼ 5 × 103) 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 ∼7%) even at low magnetic field ∼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 ∼0.20 (for grain boundaries) and ∼0.14 eV (for grains), respectively. The high εr 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.