摘要
采用固相合成工艺,制备了Bi0.5Ba0.5Fe0.5Ti0.49Nb0.01O3(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1.0μm,晶格常数相对于BaTiO3的晶格常数有所变大;室温电阻率ρ25约为107Ω·cm,热敏常数B25/85为7690K,并出现两次相变温度(403和523K),介电温谱测试确认了两次相变的存在;复阻抗谱呈现出非理想德拜模式,有两个部分叠加的Cole-Cole类半圆弧,对应于晶界和晶粒电阻;复阻抗谱虚部与频率关系显示存在两种弛豫效应,对应于晶界弛豫和晶粒弛豫;相变对晶粒的导电性能影响不大,但是对晶界的热敏性能影响较大.
The Bi0.5Ba0.5Fe0.5Ti0.49Nb0.01O3 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.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2010年第6期4253-4260,共8页
Acta Physica Sinica
基金
广西信息材料重点实验室研究基金(批准号:PF090569)资助的课题~~
