Bi0.95Mn0.05FeO3 - Ni0.5Zn0.5Fe2O4 Nanocomposites with Multiferroic Properties

Abstract

Nanoparticles of Bi0.95Mn0.05FeO3 and Ni0.5Zn0.5Fe2O4, synthesized using sol-gel autocombustion method, were mixed with the chemical formula (x). Bi0.95Mn0.05FeO3 - (1-x). Ni0.5Zn0.5Fe2O4, where x takes the values of 0, 0.5, 0.6, 0.8 and 1 to prepare multiferroic composites. The sintering of the materials was done at 800 oC for 6h in air atmosphere. Dense and homogeneous compounds with fine grained microstructures were achieved in all the composite samples as evident from the obtained scanning electron micrographs. Structural analyses of the composites were carried out using X-ray diffraction and FTIR spectroscopy and the obtained data suggests formation of diphase compounds with meek interfacial diffusion while retaining the major individual perovskite and spinel phases in all the composites. Dielectric studies as a function of temperature reveals that there is a phase transition in the composites in each case around the Neel temperature which manifests not only a transition from ferrimagnetic to paramagnetic but also a vanishing magnetoelectric order between the constituent phases. Room temperature magnetic hysteresis loops were taken using vibrating sample magnetometer. The saturation magnetization was found to increase according to the constituent percentage of the ferrite content added to the composite. Superparamagnetic behavior with close to zero coercivities was observed for all the samples. Polarization-electric field (P-E) loops provide the evidence for the existence of spontaneous polarization in all the composites. The preservation of both the ferroelectric and ferrimagnetic phases with required degree of interfacial coupling between them in these composites makes them an attractive choice for sensor and spintronic applications.