Structural, optical, magnetic and photoelectrochemical properties of (BiFeO3)1−x(Fe3O4)x nanocomposites

Abstract

(BiFeO3)1−x(Fe3O4)x nanocomposites were prepared by dispersion of Fe3O4 nanoparticles (NP) into sol–gel synthesised BiFeO3 (BFO) matrix followed by calcination at 500 °C. Samples with x = 0.0, 0.2, 0.33 and 0.5 were investigated using X-ray diffractions (XRD), UV–vis spectroscopy, photoluminescence spectroscopy (PL), transmissions electron microscopes (TEM), electron spin resonance (ESR), vibrating sample magnetometer (VSM) and photoelectrochemical (PEC) measurements. Formation of nanocomposites was confirmed by XRD and TEM. The XRD patterns showed presence of both BFO and Fe3O4 phases without any secondary phases. The crystallite size of BFO (39.1–51.1 nm) is much bigger than that of Fe3O4 (10.1–12 nm). Microstrain of BFO decreased for sample x = 0.2 and 0.33 and then increased for x = 0.5. Optical band gap of samples decreased from 2.5 eV for x = 0.0–1.96 eV for sample x = 0.5. The PL emission which centred at 428.1 eV for x = 0.0 increased gradually for samples x = 0.2 and 0.33 and then decreased for x = 0.5. Exchange bias (HEB) was observed for hysteresis loops of all samples, and the highest value of HEB was 38.4 Oe for x = 0.5. The g-values of the nanocomposites, ranged between 2.23 and 2.20, were higher than that of the BFO and Fe3O4 components. The PEC measurement showed the photocurrent density increased with x. Finally, modulations of the physical properties of BFO/Fe3O4 system were analysed and discussed in detail.