摘要
用自建的非线性介电测试装置测得了０ － ３ 型ＰＺＴ／Ｐ［ＶＤＦ（７７） － ＴｒＦＥ（２３）］ 铁电复合物厚片在不同场强和温度下的线性和非线性介电系数。对于ＰＺＴ 体积含量Φ＞ ０ ．３ 的复合物，介电系数ε１ 随测试场强的升高显著增大。在Φ＜ ０ ．１ 时，可用Ｍａｘｗｅｌｌ－ Ｇａｒｎｅｔｔ 方程拟合实验结果。Ｂｒｕｇｇｅｍａｎ 方程适合于低电场（ ＜ １ ＭＶ／ｍ ） 下复合物介电系数的预测。随着退极化场系数Ｌｚ 的改变，用Ｙａｍａｄａ 模型可拟合不同场强下复合物介电系数随Φ的变化关系。ε１ 的温度依赖性显示了明显的热滞后效应。Φ值增大导致升温过程的居里温度Ｔｃ 降低。Φ＜ ０ ．３ 时，三阶非线性介电系数ε３ 随测试场强的升高而减小，而Φ＞ ０ ．４ 试样的ε３ 在６ＭＶ／ｍ 场强下出现极小值。高Φ值的复合物具有较大的ε３ 。高ＰＺＴ 含量的复合物在相变区出现较大的ε３值。ε３ 温度谱同样显示了与ε１ 类似的表观热滞后现象。
A system for measuring nonlinear dielectric permittivity has been set up. The nonlinear dielectric permittivities of thick PZT/P[VDF(77)-TrFE(23)] 0-3 ferroelectric composite films were measured at the applied electric field ranging from 1 to 8 MV/m ( f 0 = 1 kHz) and at the temperature ranging from ambient temperature to 140 ℃. When PZT volume fraction Φ is greater than 0.3, the dielectric permittivity ε 1 of composite shows a distinct dependence on the applied electric field. Maxwell-Garnett equation is suitable for predication of ε 1 when Φ is less than 0.1. Yamada model can be used to fit best the measured permittivities while Bruggeman equation can only be used to predict ε 1 at low electric field. The temperature spectra of ε 1 reveal a thermal hysteresis phenomenon. The third order dielectric permittivity ε 3 of composite also depends on the electric field. A higher electric field produces a lower ε 3 for Φ<0.3, while ε 3 shows a lowest value at electric field 6 MV/m when Φ>0.3. The temperature spectra of ε 3 also produce an apparent thermal hysteresis phenomenon similar to that of ε 1 .
出处
《功能高分子学报》
CAS
CSCD
1999年第3期251-257,共7页
Journal of Functional Polymers
基金
国家自然科学基金
香港RGC 和香港理工大学资助
关键词
锆钛酸铅
铁电复合物
非线性介电
压电
热电
lead zirconate titanate
VDF(77)-TrFE(23) copolymer
0-3 ferroelectric composite
nonlinear dielectric permittivity
