Investigation of magnetic and electric properties of bismuth ferrite nanoparticles at different temperatures

Multiferroic bismuth ferrite shows a massive interest in its potential application in magnetic and electronic devices however maintaining high purity in bismuth ferrite nanoparticles at different temperatures is a difficult task for researchers. Several samples are prepared with different annealing temperatures and investigated in different atmospheres to recognize magnetic and electrical properties. A xerogel powder of bismuth ferrite is synthesized by the sol-gel route. The powder then anneals at 500, 600, 700, and 800 °C to form a nanostructure. X-ray diffraction analysis confirms that the annealed samples are in rhombohedral structure with R3c space symmetry and show a significant increase in crystal size and reduction in lattice strain with increasing annealing temperature. FESEM reveals the microstructural features of annealed nanoparticles which represent the conversion of spherical to cubic morphology with annealing temperature. Vibrating sample magnetometer investigations were conducted as a function of annealing and surface (300, 200, 80 K) temperatures. Insignificant variations of saturation magnetization are detected with surface temperature, but considerable degradation is observed with increasing annealing temperatures. The band-gap energy of bismuth ferrite nanoparticles annealed at 500, 600, 700, and 800 ºC is measured and significant escalation is observed from 1.93 to 2.06 eV. Electrical property analyses have been investigated as a function of frequency at different surface temperatures of 50, 100, 150, 200, 250, 300, and 350 °C. Remarkable variations are established in the electric and magnetic properties. Bismuth ferrite has been widely investigated due to its promising multifunctional device applications such as memory devices, spintronics, sensors, actuators, and photocatalytic and photovoltaic applications.