Structural, magnetic, and photocatalytic properties in Bi0.83-xLa0.17YxFeO3 nanoparticles

In this research, polycrystalline BiFeO3 (BFO) and Bi0.83-xLa0.17YxFeO3 nanoparticles (BLYxFO NPs, x = 0.0, 0.05, 0.10, 0.15, and 0.20) were prepared by sol-gel route. The effect of La3+ and Y3+ co-doped ions on crystal structure, magnetic, and photocatalytic properties was reported. The Rietveld refinement of X-ray diffraction data confirms a consecutive structural phase transition of R3c-Pbam-pnma from BFO to BLY0.20FO compound. The investigation of field-emission scanning electron microscopy (FE-SEM) images indicated that the morphology and distribution of nanoparticles are almost uniform. The energy-dispersive X-ray (EDAX) analysis confirms the elemental concentration in BLYxFO NPs. All of BLYxFO NPs revealed the weak ferromagnetic behavior. The highest magnetic parameters occur in the vicinity of the R3c/Pbam phase boundary in sample with x = 0. The change of magnetic behavior from BFO to BLY0FO was discussed based on suppressing spiral cycloid spin structure and lattice distortion in rhombohedral phase. In compounds with orthorhombic structure, only lattice distortion can be affected magnetic behavior. The direct bandgap of all samples obtained from the UV-Vis diffuse reflectance spectra using Kabelka-Munk equation. The bandgap in BLYxFO NPs decreases with substituting La ion and then increases with increasing Y content. The photocatalytic activity of BFO and BLYxFO NPs is evaluated by the degradation of methyl orange in the presence of H2O2 at pH value 2 under visible light. The photocatalytic properties enhance with doping La in BFO. However, the photocatalytic activity dependence on Y concentration has a behavior more complicated and is strongly depending on crystal structure.