ChemInform Abstract: Investigations on Bi 25 FeO 40 Powders Synthesized by Hydrothermal and Combustion-Like Processes (original) (raw)
IEEE, 2016
Pure BiFeO3 nanoparticles were synthesized by a simple sol-gel method namely modified Pechini method. The nanoparticles were calcinated at four different temperatures (450 0 C, 550 0 C, 650 0 C, 750 0 C). Requirement for extra washing step for impurity phase reduction has been eliminated by elongation of the drying duration at oven from 12 hours to 28 hours along with intermediate grinding. FESEM and X-ray Diffraction (XRD) were performed which confirm that the samples calcinated at 450 0 C and 550 0 C show smaller particle size and greater correspondence. Hence XPS was performed on these two samples which showed lower oxygen vacancies for 550 0 C. Finally the SQUID analysis has been carried out for the 550 0 C sample. A higher value of remanent magnetization and coercive field at room temperature has been observed. Besides, an asymmetric shift in the field axis with unsaturated M-H curve may be attributed to the existence of exchange bias effect in the synthesized nanoparticles. Index Terms-Multiferroics, sol-gel, nanoparticles, exchange bias effect. I. INTRODUCTION The quest for multiferroic materials is actuated not only by the simultaneous existence of ferroelectricity and ferromagnetism but also by the possible coupling of their electric and magnetic orderings [1-3]. Such property allows mutual control of the electric polarization with a magnetic field or control of magnetization by an electric field. This magnetoelectric (ME) effect is prodigiously potential in developing novel memory and spintronic devices, spin valves, oscillators, filters, thin film capacitors and sensors [4-6]. Among the available multiferroic materials of type ABO3, BiFeO 3 (BFO) having rhombohedrally distorted perovskite structure with lattice parameters of a = 5.571Å and c = 13.868Å at room temperature with high Curie temperature of T C = 820-850 0 C [1, 2], Neel temperature of T N = 350-380 0 C [3] has turned into a cynosure of many current studies. It has potential applications of magnetoelectric coupling at temperatures around room temperature [1, 5, 7, 8]. In BFO Bi 3+ contributes to ferroelectricity whereas antiferromagnetism is attributed to Fe 3+ ions. BiFeO 3 exhibits anti-ferromagnetic G-type spin conf guration along the [111] c or [001] h directions in its pseudocubic or rhombohedral structure. It has a cycloid spin structure with a periodicity of