【摘要】 用自建的非线性介电测试装置研究了陶瓷相被极化 (B1 )以及陶瓷相和共聚物相都被极化 (B2 )的钛酸铅 /聚 [偏氟乙烯 ( 70 ) 三氟乙烯 ( 3 0 ) ](PT/P[VDF( 70 ) TrFE( 3 0 ) ]) 0 3型铁电复合物厚片在不同测试场强下的非线性介电系数 .对于PT含量 >0 3的复合物 ,介电系数ε1随场强的升高明显增大 .在 <0 1时 ,可用Maxwell Garnett方程拟合实验结果 .Bruggeman方程适合于低电场 ( <1MV/m)下复合物介电系数的预测 .通过Lz 的变化 ,用Yamada模型可拟合不同场强下复合物介电系数随的变化关系 .二阶非线性介电系数ε2 随的升高而增大 ,B2的ε2 大于B1 ,说明B2具有较高的剩余极化 .三阶非线性介电系数ε3 随场强的升高而减小 ,且高值的复合物具有较大的ε3 .两相都被极化试样的ε3 小于仅陶瓷相被极化的试样 .更多还原

【Abstract】 A system for measuring nonlinear dielectric permittivity was set up. The nonlinear dielectric permittivities of thick PT/P[VDF(70)-TrFE(30)] 0\|3 ferroelectric composite films have been measured at 1kHz at applied electric field ranging from 1 to 10MV/m.When PT volume fraction  is greater thn 0\^3,the dielectric permittivity ε\-1 of composites shows a distinct dependence on electric field.The Maxwell\|Garnett equation is suitable for predication of ε\-1 when  is less than 0\^1.The Yamada model can be used to best fit the experimental results, while Bruggeman equation can only be used to predict ε\-1 at low electric field. The absolute value of the second order dielectric permittivity ε\-2 increases with increasing PT volume fraction.ε\-2 of the composites with both the ceramic and copolymer phase being poled (B2) is higher than that of composites with only the ceramic phase being poled (B1).The results show that the magnitude and direction of the remnant polarization of composite films can be determined by measuring ε\-2. In addition,ε\-2 is independent of electric field.The third order dielectric permittivity ε\-3 of composites also shows a dependence on electric field. A higher electric field produces a lower ε\-3.The ε\-3 value of B1 is always higher than that of B2 for every PT concentration.更多还原