Ti掺杂BiFeO3陶瓷的结构和铁电性能研究

用固相反应法制备了BiFe_1-xTi_xO₃(BFTxO)陶瓷样品，研究了不同Ti掺杂量对BFO陶瓷结构、形貌、铁电性能和铁电-顺电相变温度(T_c)的影响. XRD结果表明，当Ti含量x从0增大到0.2，相的结构由菱方钙钛矿逐渐变为斜方结构. Raman光谱的测试和模拟也证实了掺Ti后晶体结构有向三斜晶系转变的趋势. I-V曲线说明Ti掺杂显著降低了BFO陶瓷的漏电流，当Ti掺杂量为0.05时，漏电流最小，在100V电压下，漏电流密度为7.3×10^－6A/cm². Ti掺杂还增强了BFO陶瓷的铁电性，Ti掺杂量为0.05时的剩余极化强度甚至是纯BFO的两倍. 另外，DTA测试显示，Ti掺杂能影响BFO的铁电顺电相变温度. 随着Ti掺杂量的增加，铁电顺电相变温度逐渐降低.

Structure and Ferroelectric Properties of Ti4+-doped BiFeO3 Ceramics

BiFe_1-xTi_xO₃ (x=0,0.05,0.10,0.15 and 0.20) (BFT_xO) ceramics were prepared by the solid-state reaction technology. The effects of Ti doping on the microstructure, morphology, the ferroelectric properties and ferroelectric-paraelectric phase transition were investigated. The result of X-ray diffraction pattern implies that the rhombohedral structure is distorted to an orthorhombic structure by Ti doping. The measured Raman scattering spectra also show that Ti doping modifies the ceramic structure from rhombohedral to orthorhombic. Compared with the pure counterparts, the average grain sizes of the BiFe_1-xTi_xO₃ (x=0.05、0.10) ceramics decrease with the increase of Ti⁴⁺ concentration. The leakage current density and the remnant polarization of the BiFe_1-xTi_xO₃ (x=0.05,0.10) are improved due to the decreased oxygen vacancies by Ti⁴⁺ doping. The current density values for the pure BiFeO₃ and BiFe_0.95Ti_0.05O₃ ceramics are 1.4×10^－4A/cm² and 7.3×10^－6A/cm² at 100V, respectively. The remnant polarization (2P_r) of BiFe_0.95Ti_0.05O₃ ceramic is 2.78μC/cm² at 8kV/mm. DTA and Raman scattering spectra results indicate that the ferroelectric transition temperature (T_c) of the BFT_xO crystal is influenced by the content of Ti ions. With the increase of Ti content, the ferroelectric transition temperature decreases.