Development of Hysteresis-Free High-Precision Piezoelectric Actuators Using High Curie-Point Crystals.

压电陶瓷致动器不适用于精确的位置控制，因为它们表现出滞后和蠕变。本研究计划的目的是利用具有1160 ℃居里温度的铌酸锂晶体，研制出一种高精度的压电驱动器。本项目取得的主要成果如下：1.计算了不同取向LiNbO_3的压电常数，并寻找了最佳的切割方式。旋转140 °的Y切板具有30.3 pC/N的最大横向压电应变常数d_<23>和0.51的非常高的耦合因子k23。旋转28 °的Y型杆具有最大纵向压电应变常数<22>d_39.6pC/N和耦合因子<22>k_0.6.2。在低于居里温度下热处理形成铁电反型层的LiNbO_3板可用作弯曲致动器。研究了反型层厚度与热处理条件的关系。已经表明，足够长的热处理会导致厚达板厚一半的反型层。3.使用140 °旋转Y形切口制造的弯曲致动器已被证明具有优异的线性度、无滞后和无蠕变。4.研究了多层介质模式驱动器的各种制作方法。它证明了即使使用粘合剂层压制造的致动器也没有滞后，蠕变小，并且具有良好的线性，对于正高压和负高压都没有明确的饱和。5.压电应变常数的温度依赖性已被检查。实验结果表明，LiNbO_3陶瓷驱动器的d_1变化量<23>比陶瓷驱动器小得多，而且驱动器可以在很宽的温度范围内工作，因此，本研究所研制的LiNbO_3陶瓷驱动器非常适合于需要精确位置控制的应用场合。

Piezoelectric ceramic actuators are not suitable for precise position control, because they exhibit hysteresis and creep. The purpose of this research project is to develop hysteresis-free high-precision piezoelectric actuators using LiNbO_3 crystals with a very high Curie temperature of 1160ﾟC. The results obtained in this project can be summarized as follows: 1. The piezoelectric constants have been calculated for various orientations of LiNbO_3 and the optimum cuts have been searched. The 140ﾟ rotated Y-cut plate has a maximum transverse piezoelectric strain constant d_<23> of 30.3 pC/N and a very high coupling factor k23 of 0.51. The 28ﾟ rotated Y-bar has a maximum longitudinal piezoelectric strain constant d_<22> of 39.6 pC/N and a coupling factor k_<22> of 0.6.2. A LiNbO_3 plate with a ferroelectric inversion layer formed by heat treatment just below the Curie temperature can serve as a bending actuator The dependence of the inversion layer thickness on the heat treatment conditions has been studied. It has been shown that a sufficiently long heat treatment causes an inversion layer as thick as one-half of the plate thickness. 3. The bending actuators fabricated using 140ﾟ rotated Y-cuts have been demonstrated to exhibit excellent linearity, no hysteresis, and no creep. 4. Various fabrication methods for Multi-layer longitudinal-mode actuators have been studied. It proves that even actuators fabricated by lamination using adhesives have no hysteresis, little creep, and excellent linearity with no definite saturation for both positive and negative high voltages. 5. The temperature dependence of the piezoelectric strain constant has been examined. It has been demonstrated that the variation of d_<23> is much smaller than that of ceramic actuators and the actuators can operate over a very wide temperature range.In conclusion, the LiNbO_3 actuators developed in this research are most suitable for applications requiring precise position control.