Bi0.5Ba0.5Fe0.5Ti0.49Nb0.01O3热敏陶瓷的微结构和电学性能研究

采用固相合成工艺，制备了Bi_05Ba_05Fe_05Ti_049Nb_001O₃（BBFTN）热敏陶瓷，借助X射线衍射仪、扫描电子显微镜、阻温测试仪和交流阻抗谱考察其微结构、直流电阻、介电特性、阻抗和电学模量方面的电学性能. 结果表明：BBFTN材料依然为立方钙钛矿结构，平均晶粒尺寸约为10 μm，晶格常数相对于BaTiO₃的晶格常数有所变大；室温电 关键词： 05Ba_05Fe_05Ti_049Nb_001O₃')" href="#">Bi_05Ba_05Fe_05Ti_049Nb_001O₃ 微结构 电学性能

Study on the microstructures and electrical properties of Bi0.5Ba0.5Fe0.5Ti0.49Nb0.01O3 thermistor ceramic

The Bi_0.5Ba_0.5Fe_0.5Ti_0.49Nb_0.01O₃ thermistor has been prepared by the standard solid-state reaction method, and the microstructures, direct current resistivity, dielectric property, impedance and electric modulus were investigated by the X-ray diffraction, scanning electron microscopy, resistivity-temperature measurement and alternating current impedance spectroscopy. The results show that the material, with an average grain size of about 10 μm, still has cubic perovskite structure, and the lattice constant of the material becomes larger compared with that of the BaTiO₃. The resistivity and thermistor contant B value of the material are about 10⁷ Ω·cm and 7690 K, respectively, and the phase transition occurs twice (at 403 and 523 K), which are confirmed by the dielectric spectrum as a function of temperature. The complex impedance spectroscopy shows the non-ideal Debye type with two incomplete overlapping Cole-Cole semicircles corresponding to the grain and grain boundary resistance. The imaginary part of alternating current resistance as a function of frequency indicates there are two relaxation effects observable in the grain and grain boundary. The phase transition has little effect on the conduction property of bulk grain, but a great impact on that of the grain boundary.