PLZT陶瓷的介电弛豫行为与A位有序

DIELECTRIC RELAXATION BEHAVIOR AND A-SITE ORDERING OF La-MODIFIED LEAD ZIRCONATE TITANATE RELAXOR

用传统粉末工艺合成了（Ｐｂ＿（０．８６５）Ｌａ＿（０．０９））（Ｚｒ＿（０．６５）Ｔｉ＿（０．３５））Ｏ＿３陶瓷（ＰＬＺＴ９／６５／３５）。Ｘ射线研究表明：试样中存在着Ａ位准体心立方有序超结构，有序畴的平均尺寸为１０～２０ｎｍ。测定了１０个频率下介电常数与温度的关系，并将介电常数最大值的温度Ｔ＿ｍ与对应的频率ｆ用Ｖｏｇｅｌ－Ｆｕｌｃｈｅｒ公式拟合，得到物理上合理的激活能及指数前项值，这表明试样的介电弛豫行为与自旋玻璃态类似。基于Ａ位有序超结构及类似于自旋玻璃态的极化行为，对试样的极化全过程进行了探讨。

Pb_(0.865) La_(0.09))(Zr_(0.65) Ti_(0.35)) O_3 ceramics was synthesized by conventional powder processingtechnique.X-ray diffraction investigation reveals that A-site body-centered pseudo-cubic ordered superstruc-ture exists in the sample with an average size of 10～20nm. The dielectric constant as a function of tempera-ture was measured for ten different frequencies. The frequency dependence of the temperature of the dielectricconstant maximum was analyzed based on the Vogel-Fulcher relat ionship,obtaining reasonable resuIts forboth activation energy and preexponential factor. It is suggested that the relaxor behavior of the PLZT ce-ramics is similar to that of spin glasses. Based on these results, the polarizatiOn process is discussed.