Origin of fundamental functions in relaxor ferroelectrics

弛豫铁电体具有广泛而巨大的介电敏感性和最大的压电响应，是小尺寸大电容电容器、致动器和超声波器件的理想材料。然而，尽管迄今为止提出了各种模型，但它们巨大的介电响应的起源尚未得到很好的理解。特别是在Pb (Mg1/3Nb2/3)O3等原型弛豫剂中，在液氦温度以下，长程顺序不发展。我们认为这种现象对弛豫性质是必不可少的，并通过光学、非线性光学和中子散射技术进行了研究。我们之前的研究表明，在外加电场的作用下，长程序可以被诱导，但在不同的史前时期，长程序表现出截然不同的路径。本研究表明，在低温条件下，长时间孵育后形成长程序列，其孵育时间超过几十小时。发现弛豫过程至少分为两个过程：一个是相当快的响应过程，它遵循debye型定律；另一个是长过程，如果引入起始时间，它可以归一化。我们现在正在分析这些数据，将弹性远程相互作用力引入到金兹堡-朗道方程中。

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.