陶瓷/VDF—TrFE 0-3型铁电复合物的三阶非线性介电系数

Third Order Nonlinear Dielectric Permitivities of Ferroelectric Ceramic/VDF-TrFE 0-3 Composite Materials

在自建的非线性介电测试装置上测得了ＰＴ、ＢＴ、ＰＺＴ和ＶＤＦ—ＴｒＦＥ共聚物形成的０—３ 型铁电复合物厚片的三阶非线性介电系数ε_３．研究发现，三种复合物的ε_３都随陶瓷组分含量的上 升而增大．测试场强升高，测得的ε_３值减小，但对高陶瓷含量（φ＞０．４）的ＢＴ／ ＶＤＦ－ＴｒＦＥ和 ＰＺＴ／ＶＤＦ－ＴｒＦＥ复合物则在６ＭＶ／ｍ场强下出现极小值．二相都被预极化的复合物小于仅陶瓷相 被预极化的ε_３值．ＰＺＴ／ ＶＤＦ－ＴｒＦＥ复合物的温度依赖关系显示了与（一阶）介电系数类似的表观 热滞后现象．高ＰＺＴ含量的复合物在相变区出现较大的ε_３值．

A system for measuring nonlinear dielectric permittivity has been set up. The third order nonlinear dielectric permittivities of ferroelectric ceramic (PT, BT, PZT)/VDF-TrFE 0-3 composite thick films have ben measured at the electric field ranging from 1 to 10 MV/m (f_0=1kHz) and at the temperature ranging from ambient temperature to 140℃. It is found that the third order dielectric permittivityε_3 of three kinds of composite increases with the increase of ceramic volume fraction φ ε_3 of the composite also shows a dependence on electric field. A higher electric field produces a lower ε_3, but BT/P[VDF(70)-TrFE(30)] and PZT/ P[VDF(77)--TrFE(23)] whose φ is higher than 0.4 show a minimum at 6MV/m of electric field. ε_3 of the composite which two phases being poled is less than that of the composite which only the ceramic phase being poled. The temperature spectra of ε_3 for PZT/P[VDF(77)- TrFE(23)] also produces an apparent thermal hysteresis phenomenon similar to that of ε_1.