Multiferroic- and bandgap-tuning in BiFeO3 nanoparticles via Zn and Y co-doping

The pure and Y, Zn co-doped BiFeO3 nanoparticles were synthesized using a sol-gel method. The effect of Zn, Y co-doping on the structural, optical, electrical and magnetic properties is systematically investigated. The X-ray diffraction revealed that Y, Zn co-doping could trigger phase transformation from rhombohedral phase to cubic phase. The surface topography characterized by scanning electron microscope shows that the grain diameter decreased with increase of Y doping concentration. UV-VIS spectroscopy indicates an apparent blue shift compared to that of the undoped sample. Accordingly, the direct optical band gap of doped samples decreases from 1.43 to 1.28 eV. Meanwhile, with the increase of Y element, the leakage current property is improved as the value decreased about two orders of magnitude. Moreover, analyzing from Vibrating sample magnetometer, the magnetic properties of Zn, Y co-doped samples were improved compared to the pure BFO. In this study, the Zn, Y ions not only contribute to tune band gap, but also simultaneously play a key role in multiferroic-tuning, which offers an available way to adjust the band gap and improve the multiferroic properties of BFO based devices.