Multiferroic and optical studies on the effects of Ba2+ ions in BiFeO3 nanoparticles

Single phase Ba 2+ ions doped BiFeO 3 nanoparticles have been successfully synthesized with varied concentration (0.0 ≤ x ≤ 0.2) using the auto combustion method. The structural properties of Bi 1−x Ba x FeO 3 (x-0.0, 0.1 and 0.2) nanoparticles reveal the formation of highly crystalline rhombohedrally distorted perovskites without undergoing any structural phase transformation analyzed via Rietveld refinement. The Pauling’s equation confirmed that Ba 2+ ions doped BiFeO 3 ceramics have much more negative enthalpy of formation (Δ H f ) than undoped BiFeO 3 . A reduction of particle size has been observed up to x = 0.1 and then after increases, whereas the band gap shows a reverse trend. Magnetic and ferroelectric transition temperatures are found to be slightly shifted towards the lower temperature up to x = 0.1 and then higher temperature side which could be attributed to the particle size effect. Ba 2+ doped BiFeO 3 ceramic with concentration x = 0.2 exhibit larger magnetization as compared to others at room temperature, but these magnetization curves were not saturated. Remnant polarization is found to decrease from 7.693 to 5.141 µC/cm 2 along with the doping of Ba 2+ ions. The on-site d-to-d crystal field excitations of Fe 3+ ions associated with 6 A 1g – 4 T 1g or 6 A 1g – 4 T 2g electronic energy levels, Fe 1 3 d –Fe 2 3 d inter-site electron transfer and inter-atomic O 2 p –Fe 3 d electronic energy levels are observed by the means of absorption spectroscopy.