Synthesis and Electromechanical Behavior of "Smart" Ferroelectric Ceramics

小行星9522504 建议的研究的目的是研究的性质和幅度的循环电场裂纹扩展的效果。 大多数压电钛酸铅锆（PZT）在AC场下使用，其中组合的 机械和电气加载可以 导致组件故障。 目前开发的有限元模型 项目 将延长 到 描述 压电陶瓷在各种条件下的机电响应 的边界条件。 此外，一种新的技术，激光拉曼光谱（LRS）将被应用于直接测量裂纹尖端的应力分布所施加的电场。 将结果与使用FEA模型计算的应力进行比较。 本文的研究目标是通过对PZT陶瓷在静态和循环载荷下的裂纹扩展进行原位研究来实现的 （AC） 电动 字段， 直接 利用LRS测量了PZT陶瓷电致裂纹尖端应力，建立了描述外加电场对裂纹扩展影响的有限元模型，研究了PZT陶瓷的微观结构和成分对诱导相变的影响。 %这些 研究 会导致新一 和 基本理解 的 的 机电 响应 压电 下材料 组合 电动 和机械负载。 一种新的技术，使用LRS直接测量裂纹尖端应力将被证明沿着与诱导相变的可能性，在掺锶PZT系统。 ***

9522504 Singh The objective of the proposed research is to study the effect of the nature and amplitude of cyclic electric fields on crack propagation. Most piezoelectric leadzirconium titanates (PZTs) are used under AC fields, where the combined mechanical and electrical loading can cause component failure. Finite element models developed in the current project will be extended to describe the electromechanical response of PZT under a variety of boundary conditions. In addition, a novel technique of laser Raman spectroscopy (LRS) will be applied to directly measure the distribution of crack tip stresses produced by applied electric fields. The results will be compared with stresses calculated using FEA models. The proposed research objectives will be accomplished by performing in situ crack propagation studies in PZT ceramics under static (DC) and cyclic (AC) electric fields, directly measuring electricallygenerated crack tip stresses in situ using LRS, developing a finite element model to describe the effect of applied electric field on crack propagation, and studying the influence of microstructure and composition on the induced phase transformations in PZT ceramics. %%% These studies will lead to a new and fundamental understanding of the electromechanical response of piezoelectric materials under combined electric and mechanical loads. A new techniques using LRS for directly measuring crack tip stresses will be demonstrated along with the possibilities of induced phase transformation in the strontium-doped PZT system. ***