Effect of dopant-induced defects on structural, electrical, and enhanced ferromagnetism and magnetoelectric properties of Dy and Sr co-doped BiFeO₃

In this report, [Bi_0.95Dy_0.05FeO₃ (BDFO), Bi_0.95-xDy_0.05SrxFeO₃, x = 0.05 (BDSFO-1), and Bi_0.95-xDy_0.05SrxFeO₃, x = 0.10 (BDSFO-2)] ceramics are prepared by the solid-state reaction. Crystal structures of Dy³⁺ and Sr²⁺-substituted BFO samples are confirmed as rhombohedral with the space group (R3c) through X-ray diffraction analysis and evidenced with Reitveld refinement. The band gap energy is 2.14, 2.16, and 2.18 eV for BDFO, BDSFO-1 and BDSFO-2, respectively. Characteristic modes in Raman spectra of the samples are denoted as A₁-1, A₁-2, and A₁-3 and E, which are favorable to induce ferroelectricity of BFO. Remnant polarization measured with respect applied electric field (P-E) hysteresis loops of the samples increases with increasing Sr²⁺ concentration of BDFO. Sr²⁺-doped BFO samples represent the higher leakage current density than the Dy³⁺-doped BFO, which is attributed that the Sr²⁺ ions create the oxygen vacancies in BFO. Ferromagnetic ordering and enhanced saturation magnetizations are observed in magnetic measurements of BDSFO-1 and BDSFO-2 samples at room temperature. Furthermore, characteristics of the magneto-electric coupling were examined in through magneto-capacitance of Sr²⁺ and Dy³⁺-substituted BiFeO₃ samples.