Effect of Ca and Nb co-doping on optical and magnetoelectric properties of polycrystalline BiFeO₃ ceramics

This study uses the sol–gel method to investigate the structurally induced optical, electrical, and magnetic properties of polycrystalline BiFeO₃, BiFe_0.95Nb_0.05O_3, and Bi_0.95Ca_0.05Fe_1-xNb_xO₃ (x = 0, 0.04, 0.08) ceramics. According to X-ray diffraction patterns, all specimens largely crystallize in the R3c phase. The optical bandgap of the samples ranges from 1.81 to 1.71 eV. The leakage current density of BiFe_0.95Nb_0.05O₃ and Bi_0.95Ca_0.05Fe_0.92Nb_0.08O₃ is 1.99 × 10^–8 A/cm² and 2.09 × 10^− 9 A/cm² at 1 kV/cm, which is relatively lower than the current density of the other samples. BiFe_0.95Nb_0.05O₃ and Bi_0.95Ca_0.05Fe_0.92Nb_0.08O₃ showed saturated P-E loops with energy storage densities of 0.0106 J/cm³ and 0.0125 J/cm³, respectively. Among the samples, Bi_0.95Ca_0.05Fe_0.92Nb_0.08O₃ exhibits relatively higher ferroelectric polarization (P_max = 1.820 μC/cm²), magnetoelectric coupling (0.305 V/Oe cm), and reasonable maximum magnetization (0.325 emu/g) compared to the other samples. and can serve as a promising candidate for memory storage and photovoltaic applications.