Structural, Electrical, and Magnetic Properties of Bi0.90Nd0.10 Fe0.98TM0.02O3 (TM = Mn, Co, Ni, and Cu) Materials

Pure BiFeO3 (BFO) and Bi0.90Nd0.10Fe0.98TM0.02O3 (TM = Mn, Co, Ni, and Cu) materials have been synthesized by the sol-gel method. Effects of codoping Nd and transition metal (TM) on the structural, electrical, and magnetic properties of BFO were investigated by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, scanning electron microscope (SEM), vibrating sample magnetometry, polarization vs. electric field hysteresis loops (P-E), and complex impedance spectra measurements. A distortion of crystal structure, in which lattice parameters a and c decreased in all codoped samples, was measured by XRD. SEM images showed a significant reduction of average grain size and an obvious change in surface morphology with Nd and TM codoping in BFO. Codoped samples demonstrated various improvements in ferroelectric and ferromagnetic properties, most notably for codoped (Nd and TM) samples. Saturation magnetization (M-s) and saturation dielectric polarization (P-s) increased from M-s = 0.060 emu/g, P-s = 1.03 mu C/cm(2) for pure BFO to M-s = 0.411 emu/g, P-s = 11.08 mu C/cm(2) for a codoped (Nd and Mn) sample. Our results show that Mn is the best TM for codoping with Nd in BFO to improve its multiferroic properties.