Tuning the optical, structural and multiferroic properties of Bismuth Ferrite (BiFeO3) Nanoparticles by Doping with Ba

Abstract

Bismuth Ferrite Nanoparticles (BiFeO3 NPs) are interesting single-phase multiferroic materials due to their notable magnetoelectric properties at room temperature. We enhance the magnetization of BFO NPs via doping 5 % Ba at the Bi site. These NPs were synthesized by a modified and reproducible sol-gel technique and further characterized by XRD (x-ray diffraction), VSM (Vibrating Sample Magnetometer), PFM (Piezoresponse Force Microscopy), DSC (Differential Scanning Calorimetry) and UV-Vis (Absorption spectroscopy) techniques. Rietveld refinement unveils a lattice distortion and shows that the average crystallite size is reduced from 43.7 to 38.4 nm after Ba incorporation. 5 % Ba enhances the ferromagnetism from 0.71 to 0.86 Am2/kg at 300 K. DSC curves confirm no significant variation in magnetic transition temperature (TN) after Ba doping. Moreover, PFM data show the ferroelectric behavior of 5 % Ba doped NPs with reduced piezoresponse. UV-Vis spectra show the presence of crystal field transition and a doubly degenerate d-d transition, whereas the band gap of 5 % Ba doped BFO NPs increases from 2.18 eV for BFO NPs to 2.23 eV.