Study On Electromagnetic And Photovoltaic Properties Of Sm-doped BiFeO₃ Nanofibers

Bismuth ferrite(BiFeO3,BFO)is a single-phase multiferroic material that has both ferroelectric and antiferromagnetic properties at room temperature.As a multifunctional material,it has potential applications in multi-state memories,new magnetoelectric sensors,and spintronic devices,et al.In this paper,starting from the one-dimensional structure of BFO,combined with chemical element doping,one-dimensional structure of BFO and Sm-doped BFO nanofibers were prepared by electrospin1ing.The effects of Sm3+ doping on the phase structure,magnetic,dielectric,ferroelectric,piezoelectric and photovoltaic properties of BFO nanofibers were systematically investigated.The morphology of the annealed BFO nanofibers was linear,and the diameter of them was about 100～200 nm.XRD shows that as the concentration of Sm3+increases,the 104 diffraction peak of BFO gradually shifts to the right and eventually merges into a single peak with the 110 peak,which causes the transform from the rhombohedral to tetragonal/orthorhombic structure.The magnetic properties of BFO nanofibers doped with Sm3+ at the same concentration are always higher than those of nanoparticles,and the magnetic properties of BS10FO nanofibers are almost twice that of BS10FO nanoparticles.The magnetic enhancement is related to the destruction of the spin periodic cycloid structure and the increase of nanofiber surface spin.BS5FO nanofibers show more dependence on bias voltage,which means that BS5FO nanofibers have more alignment of dipoles and better ferroelectricity.The dielectric constant and dissipation factor of Sm-doped nanofibers fluctuate slightly below 250℃,so they have potential applications in micro-nano sensors,memories,drivers et al.The domain phase of a single BFO and Sm-doped BFO nanofiber exhibit a 1800 switching characteristic at an external voltage,and the displacement exhibit a strain characteristic at an external voltage,demonstrating the ferroelectric and piezoelectric properties of the nanofibers.The prepared BFO nanofibers-interdigital electrodes device and BS5FO nanofibers-interdigital electrodes device exhibit a photovoltaic effect.The devices have large open circuit voltage,and the photoelectric conversion efficiency of the BS5FO device is increased by about 1.65 times compared with the BFO device.