摘要
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.
基金
国家自然科学基金
香港RGC和香港理工大学资助项目