Ferroelectric and ferromagnetic properties of Gd-doped BiFeO₃-BaTiO₃ solid solution

The solid solutions of Bi_1-x-yGd_xBa_yFe_1-yTi _yO₃ have been prepared via solid-state reaction method with the aim to obtain magnetoelectric coupling (i.e., linear relation between magnetization and electric field) at room temperature. Optimum calcination and sintering strategies for obtaining pure perovskite phase, high density ceramics and homogeneous microstructures have been determined. All the samples of the composition Bi_1-x-yGd_xBa_yFe_1-yTi _yO₃ (x = 0.1 and y = 0.1, 0.2, and 0.3) reported in the present work are tetragonal at room temperature. The maximum ferroelectric transition temperature (T_c) of this system was 150-170 °C with the dielectric constant peak of 2300 at 100 kHz for y = 0.1. Above T_c the dielectric constant is decreasing up to a certain temperature and then increasing with temperature similar to that observed in other perovskites due to chemical inhomogeneities in both A and B sites of the ABO₃ cell. The variation of ferroelectric and magnetic properties was followed by piezoresponse force microscopy and vibrating sample magnetometer, respectively. Well-saturated piezoelectric loops were observed for all composition indicating room temperature ferroelectricity.