陶瓷型铁电复合物厚片介电系数的电场依赖性

DEPENDENCE OF DIELECTRIC PERMITTIVITY ON ELECTRIC FIELD FOR THICK CERAMIC-TYPE FERROELECTRIC COMPOSITE FILMS

建立起高压介电测试装置和相应的数据处理方法。研究了 PZT/P(VDF- Tr FE)和 PT/P(VDF- Tr FE) 0 - 3型铁电复合物厚片介电系数的电场依赖性。对于陶瓷体积分数 φ>0 .3的复合物 ,介电系数随测试场强的升高明显增大。在 φ<0 .1时 ,可用 Maxwell- Garnett方程拟合试验结果。Bruggeman方程适合于低电场 (<1 MV/m)下复合物介电系数的预测。通过 Lz的变化 ,用 Yamada模型可拟合复合物介电系数随电场变化的关系 ,说明 Lz是由复合物的组分维数、粒子形状以及粒子间静电相互作用所决定的参数。

Measuring apparatus and data processing method of dielectric permittivity at high voltage have been set up. Dependence of dielectric permittivity on electric field for thick PZT/P(VDF TrFE) and PT/P(VDF TrFE) 0 3 ferroelectric composite films has been investigated. The dielectric permittivity increases obviously with the increase of applied field for the composite with the volume fraction of ceramic φ more than 0 3. Maxwell Garnett equation can only be used to predict permittivity of the composite when φ is less than 0 1. Bruggeman equation is suitable for the prediction of dielectric permittivity of composite under low electric field (<1 MV/m). For the dependence of dielectric permittivity on electric field, good agreement is found between the measured permittivity and the prediction of Yamada model with the change of parameter L z, which indicates that L z is determined by dimension of the component, grain shape and static interaction among the grains.