Existence of internal domains in (Bi0.5La0.5FeO3)(1-x)-(Ba0.7Sr0.3TiO3)x solid solution and their effects on magnetic and dielectric behaviour

A significant experimental effort has been undertaken to evaluate the doping effect of La3+ at Bi-site in solid solutions of BiFeO3 (BFO) and Ba0.7Sr0.3TiO3 (BST) through various techniques like x-ray diffraction, magnetic measurements, and frequency and/or temperature dependent impedance spectroscopy. The magnetic isotherm at room temperature in La doped BFO (BLFO)-BST solid solution indicates weak ferromagnetism due to improvement in the homogeneous canted spin structure. The elusive nano-sized domain structure inside the grains of 40% BST co-doped BLFO was observed by a scanning electron microscopy technique. The domains and domain boundaries are generally formed inside the grain due to strained/unstrained lattice defects and/or mismatch with the substitution of ions of different sizes at the A and B sites. An equivalent circuit model (internal barrier layer capacitor), based on domain, domain boundary; and grain boundary relaxations, has been established to justify the enhancement of the dielectric response with BST concentrations. Published by AIP Publishing.