Enhanced magnetic and magnetoelectric properties of Mn doped multiferroic ceramics

Single phase multiferroics of BiFeO3 (BFO) and Mn doped Bi0.93Mn0.03FeO3 (BMFO), and composite multiferroic systems of BiFeO3-Ni0.5Zn0.5Fe2O4 (BFO-NZFO) and Mn doped Bi0.95Mn0.05FeO3-Ni0.5Zn0.5Fe2O4 (BMFO-NZFO) have been prepared by using sol-gel autocombustion and solid state methods. Rietveld analysis on the BFO and BMFO samples reveals rhombohedrally distorted single phase R3c perovskite structures while that of the multi-phase composites exhibit both spinel (for the NZFO) and perovskite phases. Scanning electron micrographs of the samples show uniformly dispersed fine grained microstructures with indications of decreased grain size for the Mn doped samples. Polarization-electric field hysteresis (P-E) loops on the samples exhibit spontaneous ferroelectric polarizations with specific enhancements in the remnant polarization by the Mn doping either in the single phase BMFO or in the multi-phase BMFO-NZFO composite. Room temperature magnetic hysteresis (M-H) loop measurements on the samples indicate that the doping of Mn in bismuth sites in the BFO has produced a considerable improvement in the magnetization, and the Mn doped BMFO-NZFO composite has shown further improvement in its value compared to that of the undoped BFO-NZFO composite. Thus, it can be inferred from the above that the Mn doping in single phase/composite BiFeO3 based multiferroic ceramics is capable of enhancing both the ferroelectric and ferromagnetic properties and thereby the magnetoelectric (M-E) coupling as evident from the obtained M-E curves.