FRG: Domain Orientation and Anisotropy in Poled Piezoelectrics

本项目将最先进的材料加工和表征技术应用于压电氧化物材料的研究，以建立畴取向和各种极化机制之间的定量联系。研究了电、机械和机电过程中的单调极化和循环极化，以确定它们对材料内多晶织构和畴取向的影响。反过来，纹理信息将与材料的压电响应相关，从而提供对这些材料的加工，结构和性能之间相互关系的基本理解。我们还将研究材料在使用条件下的退化，试图减轻压电疲劳的过程。压电材料作为各种器件的有源元件越来越重要，包括各种类型的应变传感器、线性执行器和用于手机等高频应用的非磁性电微变压器。在所有这些应用中，材料的性能与它的加工方式密切相关。由于大多数压电材料对应力（或相反地对电场）的响应仅在与其晶体学相关的单一方向上，因此设计期望响应方向与材料晶体结构相关的器件是有意义的。然而，如果材料由随机取向的晶体组成，具有随机取向的压电响应方向，则没有机会实现如此高效的器件设计。在这个项目中，我们寻求找到实用的、低成本的方法来开发晶体排列，从而在振动传感器和主动振动阻尼系统等应用中优化设备性能。

This project applies state-of-the-art techniques of materials processing and characterization to the study of piezoelectric oxide materials, to establish quantitative links between domain orientation and the various mechanisms of poling. Monotonic and cyclic poling via electrical, mechanical and electromechanical processes are investigated, to determine their effects on the polycrystalline texture and domain orientation within the materials. The texture information, in turn, will be correlated to the piezoelectric response of the material, providing a fundamental understanding of the interrelationships between the processing, structure and properties of these materials. We will also study the degradation of the materials under service conditions, attempting to mitigate the process of piezoelectric fatigue.Piezoelectric materials are increasingly important as the active components of a wide range of devices, including various types of strain sensor, linear actuators and non-magnetic electrical microtransformers for high-frequency applications such as cell-phones. In all of these applications, the performance of the material is strongly linked to the manner in which it is processed. Since most pieozoelectric materials respond to stress (or conversely to electric fields) only in a single direction, related to their crystallography, it makes sense to design devices in which the desired response direction is related to the crystal structure of the material. If, however, the material is comprised of randomly-oriented crystals, with randomly-oriented piezoelectric response directions, there is no opportunity to achieve such an efficient device design. We seek, in this program, to find practical, low-cost methods of developing crystalline alignment that allows for optimized device performance, in applications such as vibration sensors and active vibration damping systems.