Influence of Gd doping on the visible-light photocatalytic activity and magnetic properties of BiFeO3 particles

Abstract

In the present study, Gd-doped BiFeO3 (GBFO) particles were synthesized using the sol-gel technique. The influence of Gd doping on the structural, morphological, photocatalytic, and magnetic properties of the GBFO particles was then investigated. Structural analyses revealed that a gradual crystal symmetry transition from rhombohedral to orthorhombic occurred in the BiFeO3 (BFO) particles with increasing Gd doping level. X-ray photoelectron spectra showed a decrease in the number of oxygen defect states upon Gd doping. The photocatalytic activity of the prepared GBFO particles was studied by monitoring the photocatalytic decomposition of methylene blue and rhodamine B under visible light irradiation. The results showed that with increasing Gd doping levels, the degradation efficiencies increased up to an optimal value and then decreased. A maximum degradation efficiency was obtained for the GBFO particles doped with 5% Gd, which could be ascribed to the lower amounts of impurity phases and surface oxygen defect states, resulting in a higher number of charge carriers available to produce hydroxyl radicals, thereby enhancing the photodegradation efficiency. Magnetic measurements revealed an initial gradual increase in the magnetization values with increasing Gd doping concentration, which could be due to the breakdown of crystal symmetry and destruction of the cycloidal spin structure following the incorporation of Gd in the BFO lattice.