FRG: Domain Orientation and Anisotropy in Poled Piezoelectrics

Purdue University, West Lafayette IN

Investigators

Abstract

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.