Investigation of Tb-doping on structural transition and multiferroic properties of BiFeO_3 thin films

摘要

Pure BiFeO_3 (BFO) and Bi_(1-x)Tb_xFeO_3 (BTFO) thin films were successfully prepared on FTO (fluorine doped tin oxide) substrates by the sol-gel spin-coating method. The effects of Tb-doping on the structural transition, leakage current, and dielectric and multiferroic properties of the BTFO thin films have been investigated systematically. XRD, Rietveld refinement and Raman spectroscopy results clearly reveal that a structural transition occurs from the rhombohedral (R3c:R) to the biphasic structure (R3c:H+R-3m:R) with Tb-doping. The leakage current density of BTFO_(x=0.10) thin film is two orders lower than that of the pure BFO, i.e. 5.1 × 10~(-7) A/cm~2 at 100 kV/cm. Furthermore, the electrical conduction mechanism of the BTFO thin films is dominated by space-charge-limited conduction. The two-phase coexistence of BTFO_(x=0.10) gives rise to the superior ferroelectric (2P_r= 135.1 μC/cm~2) and the enhanced ferromagnetic properties (M_s=6.3 emu/cm~3). The optimal performance of the BTFO thin films is mainly attributed to the biphasic structure and the distorted deformation of FeO_6 octahedra.