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

(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 degrees 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 (39.1-51.1nm) is much bigger than that of Fe3O4 (10.1-12nm). 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 2.5eV for x=0.0-1.96eV for sample x=0.5. The PL emission which centred at 428.1eV for x=0.0 increased gradually for samples x=0.2 and 0.33 and then decreased for x=0.5. Exchange bias (H-EB) was observed for hysteresis loops of all samples, and the highest value of H-EB was 38.4Oe 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.(a) Low magnification TEM image of (BiFeO3)(x)(Fe3O4)(x) composites showing dispersion of Fe3O4 small particles (some was indicated by white arrow) into BiFeO3 matrix. (b) PL spectra of sample x=0.5, (c) Top view of PEC setup (where 1 : PC, 2 : Autolab system and 3: halogen lamp) (d) side view of PEC setup (4: PEC cell and 5 : manual chopper) and (e) Photocurrent against voltage under chopped illumination of x=0.5. [GRAPHICS] . Highlights(BiFeO3)(1-x)(Fe3O4)(x) composites were successfully synthesised.Lattice parameter c of BFO decreased with increasing Fe3O4 content, x.(BiFeO3)(1-x)(Fe3O4)(x) composites shows fascinating physical properties, such as exchange bias.The (BiFeO3)(1-x)(Fe3O4)(x) composites exhibited reduced optical band gap.PEC measurement showed the photocurrent density increased with x.The study showed a presence of interaction between the BiFeO3 and Fe3O4 resulting in modulated physical properties.