The giant electromechanical response in ferroelectric relaxors as a critical phenomenon
The giant electromechanical response in ferroelectric relaxors as a critical phenomenon
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DOI：
10.1038/nature04854
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发表时间：
2006-06-22
期刊：
影响因子：
64.8
通讯作者：
Blinc, R.
中科院分区：
文献类型：
--
作者：
Kutnjak, Z.;Petzelt, J.;Blinc, R.
一种材料将电能直接转化为机械能，这与许多应用有关。铁电“弛豫剂”（1-4）如Pb(Mg1/3Nb2/3) O-3-PbTiO3 （PMN-PT；参考文献5,6）说明了这一点：这些材料表现出巨大的机电（压电）响应，可用于超声波(4)和医疗应用，以及电信。然而，这种效应的起源尚不清楚。在这里，我们表明PMN-PT（以及潜在的其他铁电弛豫器）中的巨大机电响应是在该系统的相图中定义一条线的临界点的表现。具体来说，在PMN-PT的电场-温度-成分相图中（成分随PT浓度的变化而变化），一阶准电铁电相变终止于压电系数最大的临界点线。在这条线上，可以观察到超临界演化。在接近临界点时，诱导铁电极化旋转所需的能量成本和电场都显著降低，从而解释了这些弛豫器的巨大机电响应。
The direct conversion of electrical energy to mechanical work by a material is relevant to a number of applications. This is illustrated by ferroelectric 'relaxors'(1-4) such as Pb(Mg1/3Nb2/3) O-3-PbTiO3 (PMN-PT; refs 5, 6): these materials exhibit a giant electromechanical ( piezoelectric) response that is finding use in ultrasonic(4) and medical applications, as well as in telecommunications. The origins of this effect are, however, still unclear. Here we show that the giant electromechanical response in PMN-PT ( and potentially other ferroelectric relaxors) is the manifestation of critical points that define a line in the phase diagram of this system. Specifically, in the electric-field -temperature-composition phase diagram of PMN-PT ( the composition being varied by changing the PT concentration), a first-order paraelectric ferroelectric phase transition terminates in a line of critical points where the piezoelectric coefficient is maximum. Above this line, supercritical evolution is observed. On approaching the critical point, both the energy cost and the electric field necessary to induce ferroelectric polarization rotations decrease significantly, thus explaining the giant electromechanical response of these relaxors.