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

In this report, [Bi0.95Dy0.05FeO3 (BDFO), Bi0.95-xDy0.05SrxFeO3, x=0.05 (BDSFO-1), and Bi0.95-xDy0.05SrxFeO3, 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 2.18eV for BDFO, BDSFO-1 and BDSFO-2, respectively. Characteristic modes in Raman spectra of the samples are denoted as A(1)-1, A(1)-2, and A(1)-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.