Influence of Ba and Mo co-doping on the structural, electrical, magnetic and optical properties of BiFeO3 ceramics

Abstract

In this work, Bi0.8 Ba0.2 Fe1-xMox O3 (x = 0, 0.5, 0.10 and 0.15) ceramics were synthesized by conventional solid-state reaction to evaluate the influence of Ba2+ and Mo6+ co-doping on the structure, morphology, electrical, magnetic and optical properties of BiFeO3 ceramic. Rietveld refinement of X-ray diffraction data was done to obtain the subtle structural information. A tetragonal structure of P4mm type was revealed for Bi0.8 Ba0.2 FeO3 (x = 0) ceramic. Evolution of rhombohedral (R3c) phase was observed with Mo6+ doping and a complete transformation to R3c phase from P4mm was found for 15 wt% Mo6+ doping. This type of transformation causes distortion in the structure and results in changing bond angle. Magnetization was found to be improved with increasing the percentage of Mo6+ up to 10 wt%. Canting ofspin due to the change in Fe-O-Fe bond angle is believed to be the main reason behind this improvement. One secondary phase BaMoO4 was found and becomes prominent with Mo6+ doping. Possible formation of this impurity and its correlation with properties are explained. Microstructural analysis was done to observe the Ba2+ and Mo6+ co-doping effect on grain size and distribution. A correlation of grain size with electric and magnetic properties is drawn and elucidated. Dielectric constant shows an increasing trend with Mo6+ doping. Reduction in oxygen vacancy, due to charge compensation upon high charged Mo6+ addition, believed to be the staple reason behind the dielectric constant increment. Lastly, optical band gap energy found to be decreased with the addition of Mo6+ and possible reasons behind this are evaluated. Overall, codoping of Ba2+ and Mo6+ found to have a positive influence over materials electrical, optical as well as magnetic property.