Effect of rare-earth Nd/Sm doping on the structural and multiferroic properties of BiFeO3 ceramics prepared by spark plasma sintering

Multiferroic Nd/Sm-doped BiFeO3 ceramics synthesized at 700 degrees C by spark plasma sintering in conjunction with sol-gel precursor powders are investigated by X-ray diffraction, scanning electron microscopy, dielectric, ferroelectric and magnetic measurements. With the doping content of Nd/Sm beyond 10 mol%, the crystal structure changes from R3c to coexistence of Pbam and R3c. It is also revealed that the grain size for all samples greatly decreases and the dielectric, ferroelectric and magnetic properties are obviously improved with Nd/Sm doping. The optimized remanent polarization are about 1.451 mu C/cm(2) and 3.448 mu C/cm(2) for the 10 mol% Nd-doped and 15 mol% Sm-doped BiFeO3 ceramics, respectively. Because of the reduced concentration of oxygen vacancies, the leakage current density of Nd/Sm-doped ceramics decreases more than two orders of magnitude compared to the pure BiFeO3 sample. The maximum remanent magnetization for the Sm-doped ceramics is approximately 0.279 emu/g, which is higher than that for the Nd-doped samples (0.263 emu/g).