Structural and multiferroic properties of barium substituted bismuth ferrite nanocrystallites prepared by sol-gel method

摘要

Nanocrystalline Bi_(1-x)Ba_xFeO_3 (0≤x≤0.3) multiferroics were efficiently obtained by sol-gel method after sintering at 800 °C for one hour. The Ba substitution in BiFeO_3 (BFO) strongly modifies its structural and multiferroic properties. XRD studies revealed the structural transition from distorted rhombohedral (R3c) to pseudo-cubic (Pm3m) crystal symmetry. The magnetization increases appreciably for x=0.1, which is due to spin canting of magnetic moments at the nanoparticle surfaces and decreases afterward. From the temperature dependent magnetization studies, it is found that magnetic transition temperature (T_N) is 620 K for x=0 and 640 K for x=0.1. Besides, the maximum polarisation value decreases with increasing Ba content. SEM micrographs revealed the formation of cubic nanocrystallites with increased porosity on Ba substitution. FTIR analysis of the samples also supports the structural change towards increased crystal symmetry.