Electromechanical properties

该研究项目是一项合作提案的一部分，旨在探索组成为RX2Z2O(BO3)3的压电稀土氧硼酸盐的结构/性能关系，其中X， Z = Ca, R = La， Y, Gd, Pr, Nd, Er。重点是机电性能，因为这些不仅是基本的兴趣，而且对材料作为高温压电材料的潜在应用起着关键作用。为此，采用多种实验方法研究了所选单斜稀土氧硼酸盐的单晶压电和弹性系数随温度、频率和晶体结构/化学成分的函数关系。基本目标是(i)制定这些晶体物种的宏观性质如何受结构参数控制的规则；（ii）确定在约800°C以上的热容量和热膨胀演变中观察到的不连续的原子过程。后者直接影响材料在高温下用于压电传感器的应用。

The research project is part of a collaborative proposal which aims on the exploration of structure/property relationships of piezoelectric rare earth oxoborates of the composition RX2Z2O(BO3)3 with X, Z = Ca and R = La, Y, Gd, Pr, Nd, Er. The focus is on electromechanicalproperties, because these are not only of basic interest but play a key role for potential applications of the materials as high-temperature piezoelectrics. To this end single crystal piezoelectric and elastic coefficients of selected monoclinic rare earth oxoborates are studied as functions of temperature, frequency and crystals structure / chemical composition employing a broad variety of experimental methods. The fundamental objectives are (i) to develop rules how the macroscopic properties of these crystal species are controlled by structural parameters and (ii) to identify the atomistic processes responsible for the observed discontinuities in the evolution of heat capacity and thermal expansion above about 800 °C. The latter has direct impact on the use of the materials for piezoelectric sensor applications at high temperatures.