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The degradation of piezoelectric ceramics for actuator applications

Objective



Research objectives and content
The objective of the proposed research is to improve the current understanding of the mechanical origin of effects that influence the electromechanical behaviour of piezoelectric ceramics. In particular the degradation of their piezoelectric and mechanical properties which will ultimately limit their performance and potential applications. Piezoelectric ceramics are already used widely for mechanical actuators, ultrasonic applications, resonators and load sensors. For most applications they do not require high strength, but more importantly they do require long term stability and reliability. The electrical and mechanical cycling of piezoelectrics, however, can cause irreversible microstructural damage in the form of microcracking and reversible damage in the form of ferroelectric domain reorientation. This leads to non-reproducibility and degradation of electromechanical properties and increased electrical and mechanical losses. It is well known, for instance, that the performance of piezoelectric displacement actuators degrade during long-term applications. The problem is becoming more important as components are increasingly being used in applications that subject them to relatively large cyclic electrical and mechanical loading.
Training content (objective, benefit and expected impact)
Working in the Fracture, Creep and Fatigue group at QMW will provide a very active and stimulating environment in which to develop my research skills. The experience and skills of the researchers within the group will be of considerable assistance to me in achieving the objective,s .of my proposed research. The group has an international reputation and attracts many visitors for short and long stays -it was during a short research visit that I made my initial contact with Dr. Reece-. This will provide me with an opportunity to discuss my work and develop contacts with researchers in other important laboratories around the world. The group has excellent testing equipment, which will enable me to learn new skills. The proposed research is a good progression of my previous work and will enable me to broaden my experience to the technologically important piezoelectric materials. The training I will receive will provide me with valuable experience on all aspects of research.
Links with industry / industrial relevance (22)
The research I have proposed is related to an important industrial problem, the electromechanical degradation of piezoelectrics. Dr. Reece s research on the electromechanical fatigue of piezoelectrics has recently (January 1998 to January 2001 ) been funded by a major grant from the British Engineering and Physical Research Council (EPSRC). The project involves collaboration and support by Morgan Matroc, the major producer of piezoelectric materials in the UK which has European operations in other countries. My contact with the company throughout the fellowship would provide valuable industrial input and insight into the problems I am studying. It would also provide me with the opportunity to develop contacts within the UK industry that may be of considerable use to me later in my career.

Coordinator

QUEEN MARY AND WESTFIELD COLLEGE - UNIVERSITY OF LONDON
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