Effect of Microstrain on the Magnetic Properties of BiFeO3 Nanoparticles

TLDR: In this article, the size induced microstrain-dependent magnetic properties of BiFeO3 nanoparticles were investigated and it was found that the micro-strain is high (e.g., 0.3%) for smaller crystallite sizes and shows a sharp decrease as the particle size increases.

Abstract: We report on size induced microstrain-dependent magnetic properties of BiFeO3 nanoparticles. The microstrain is found to be high (e > 0.3%) for smaller crystallite sizes (d < 30 nm), and shows a sharp decrease as the particle size increases. The presence of pseudo-cubic symmetry is evidenced for these nanoparticles. Raman spectral studies suggest straightening of the Fe-O-Fe bond angle accompanied by a decrease in FeO6 octahedral rotation for d < 65 nm. The magnetization shows a dip around 30 nm, half the size of spin cycloid length for BiFeO3, due to a decrease in rhombohedral distortion with crystallite size. We also observe a similar trend in the TN with respect to size indicating that the microstrain plays a significant role in controlling the magnetic property of BiFeO3.