Santos Oliveira_Utilization of Piezoelectric Ceramics in Generators (Final Draft) - Utilization of the Piezoelectric Ceramic PZT in Generators LUANA

Santos Oliveira_Utilization of Piezoelectric Ceramics in Generators (Final Draft)

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Utilization of the Piezoelectric Ceramic PZT in Generators LUANA STEPHANIE SANTOS OLIVEIRA University of Kentucky Department of Materials Engineering Ceramic Engineering and Processing MSE 403 Dr. Thom Cochell Abstract: Piezoelectricity is a property observed in some materials in which polarization is induced and an electric field is established when the material is subjected to a mechanical strain. With this property, ceramic materials such as PZT can be used in generators to produce electricity. This material shows superior coefficients in properties such as density, relative permittivity, elastic modulus, piezoelectric constant, which makes it fully applicable. March 31, 2014 Lexington, Kentucky 1. Introduction
1.1 Introduction to Piezoelectricity Piezoelectricity is a property observed in certain classes of crystalline materials that, when subjected to a mechanical strain, polarization is induced and an electric field is established across the specimen proportional with the pressure. The inverse piezoelectric effect is also displayed by this group of materials; that is, a mechanical strain results from the imposition of an electrical field. [1] Both effects are manifestations of the same fundamental property of the crystal, and they occupy a position among those physical phenomena which are reversible. [2] For a crystal to exhibit the piezoelectric effect, its structure should have no centre of symmetry. Due to their characteristics, piezoelectric materials have been found to be very effective for use in dynamic applications involving vibration suppression, sensing, sonar, audio buzzers, air ultrasonic transducers (e.g. television remote controls), piezoceramic ignition systems and numerous other applications. [3] 1.2 History of Piezoelectricity The first experimental demonstration of a connection between macroscopic piezoelectric phenomena and crystallographic structure was published in 1880 by the brothers Pierre and Jacques Curie. Their experiment consisted of a conclusive measurement of surface charges appearing on specially prepared crystals which were subjected to mechanical stress. But the first serious applications work on piezoelectric devices just took place during World War I. In 1917, Paul Langevin began to perfect an ultrasonic submarine detector. Working on past the end of the war, he did achieve their goal of emitting high frequency sound waves underwater and measuring depth by timing the return echo. The strategic importance of their achievement was not overlooked by any industrial nation, however, and since that 2
time the development of sonar transducers, circuits, systems, and materials has never ceased. Between 1920 and 1940, these transducers found use in a number of devices including microphones, accelerometers, ultrasonic transducers, bender element actuators, phonograph pick-ups and signal filters. During World War II, research groups in the United States, Soviet Union and Japan discovered that certain ceramic materials exhibited dielectric constants up to 100 times higher than common cut crystals. Furthermore, the same class of materials was made to exhibit similar

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