Synthesis and size dependent properties of multiferroic BiFeO3 nanoparticles

Abstract

Utilization of Bismuth Ferrite (BiFeO3) into modern device applications is restricted by its very low magnetic moments and high leakage current. Enhancement in magnetization is a real challenge for multiferroic BiFeO3 in the context of device miniaturization and high density information storage system. In this study a significant improvement in magnetization has been recorded for BiFeO3 nanoparticles, exploiting the beneficial effect of size confinement and low shape anisotropy. BiFeO3 nanoparticles with different size in the range of 21-68 nm are synthesized via modified Pechini sol-gel approach. Ethylene glycol with a concentration of 0.05M has been successfully used as surfactant agent during synthesis process. An effective organic acid (acetic acid) is used for washing purpose instead of conventional use of nitric acid. X-ray diffraction result confirms pure, well crystallized and isotrophic regular shaped BiFeO3 annealed at temperature lower than 600°C, compared to more than 800°C for the traditional solid-state sintering process. A strong size-dependent magnetization which increases with decreasing particle size is confirmed with a value of 1.4 emu/g for 40 nm particles in contrast to 7.5 emu/g for 21 nm particles. The homogeneous shape and distribution of the synthesized particles is found to be associated with the improved ferromagnetic properties.