Origin of fundamental functions in relaxor ferroelectrics

弛豫铁电体具有宽而大的介电常数和最大的压电响应，是一种很有前途的大容量小型电容器、驱动器和超声波器件的材料。然而，其巨大的介电响应的起源并没有很好地理解，虽然各种模型已经提出了到目前为止。特别是，在一些原型弛豫器，如Pb（Mg 1/3 Nb 2/3）O 3，长程有序是不发展到液氦温度。我们认为这种现象是必不可少的弛豫性质，并已调查的光学，非线性光学和中子散射技术的手段。我们以前的研究表明，长程有序可以在外加电场下诱导，但显示出相当不同的路径，如果样品经历不同的预历史。本研究阐明了长程有序是在低温下长时间孵育（超过几十小时）后形成的。弛豫过程至少可分为两类：一类是服从Debye型定律的快速响应过程，另一类是引入起始时间后可归一化的长过程。我们现在正在分析这些数据，将弹性长程相互作用力引入金-朗道方程。

Relaxors ferroelectrics exhibit broad and huge dielectric susceptibility and the biggest piezoelectric response and are promising materials for small-size capacitors with large capacitance, actuators and ultra-sonic devices. However, the origin of their colossal dielectric response is not well understood, although various models have been proposed so far. In particular, in some prototype relaxors such as Pb (Mg1/3Nb2/3)O3, the long-range order is not developed down to liquid helium temperature. We think that this phenomenon is essential for relaxor properties and have investigated by means of optical, nonlinear optical and neutron scattering techniques. Our previous study revealed that the long-range order can be induced under the applied electric field but shows quite different paths if the specimen experiences different pre-history. The present study clarified that the long-range order develops after long incubation time, which overpasses several ten hours in low temperature. The relaxation processes are found to be classified by at least two processes : One is rather fast response which obeys the Debye-type law and the other is the long process which can be normalized if we introduced an onset time. We are now analyzing these data introducing the elastic long-range interaction force into the Ginzburg-Landau equation.