Sol-Gel Synthesis of BiFeO3 Nanoparticles

Among the various multiferroic materials bismuth iron oxide is a promising candidate due to its relatively high antiferromagnetic Neel temperature and high ferroelectric Curie temperature as compared to all other multiferroic materials. But synthesis of pure phase BiFeO3 is difficult due to the volatile nature of Bi2O3 that leads to bismuth deficient phases and if excess of bismuth is employed it give rise to bismuth rich phases. Moreover the synthesis of pure phase BiFeO3 requires high temperature annealing in the range of 400-700˚C. However, we here report sol-gel synthesis of bismuth iron oxide nanoparticles at low temperatures of 100-300˚C. These nanoparticles are characterized using XRD and VSM. The nanoparticles annealed at 100˚C results in amorphous behavior. Whereas peaks corresponding to pure phase bismuth iron oxide emerges at annealing temperatures of 200 and 300˚C. The nanoparticles show ferromagnetic behavior as opposed to antiferromagnetic behavior due to suppression of spiral spin structure.