This led to intense research to develop barium titanate and later lead zirconate titanate materials with specific properties for particular applications.ĭevelopment of piezoelectric devices and materials in the United States was kept within the companies doing the development, mostly due to the wartime beginnings of the field, and in the interests of securing profitable patents. Ultrasonic time-domain reflectometers (which send an ultrasonic pulse through a material and measure reflections from discontinuities) could find flaws inside cast metal and stone objects, improving structural safety.ĭuring World War II, independent research groups in the United States, Russia, and Japan discovered a new class of human-made materials, called ferroelectrics, which exhibited piezoelectric constants many times higher than natural materials. The development of the ultrasonic transducer allowed for easy measurement of viscosity and elasticity in fluids and solids, resulting in huge advances in materials research. Ceramic phonograph cartridges simplified player design, were cheap and accurate, and made record players cheaper to maintain and easier to build. Piezoelectric devices found homes in many fields. Over the next few decades, new piezoelectric materials and new applications for those materials were explored and developed. The use of piezoelectricity in sonar, and the success of that project, created intense development interest in piezoelectric devices. By emitting a high-frequency chirp from the transducer, and measuring the amount of time it takes to hear an echo from the sound waves bouncing off an object, one can calculate the distance to that object. The detector consisted of a transducer, made of thin quartz crystals carefully glued between two steel plates, and a hydrophone to detect the returned echo. In France in 1917, Paul Langevin and his coworkers developed an ultrasonic submarine detector. The first practical application for piezoelectric devices was sonar, first developed during World War I. This culminated in 1910, with the publication of Woldemar Voigt's Lehrbuch der Kristallphysik (textbook on crystal physics), which described the 20 natural crystal classes capable of piezoelectricity, and rigorously defined the piezoelectric constants using tensor analysis. More work was done to explore and define the crystal structures that exhibited piezoelectricity. The Curies immediately confirmed the existence of the converse effect, and went on to obtain quantitative proof of the complete reversibility of electro-elasto-mechanical deformations in piezoelectric crystals.įor the next few decades, piezoelectricity remained something of a laboratory curiosity. The converse effect was mathematically deduced from fundamental thermodynamic principles by Gabriel Lippmann in 1881. The Curies, however, did not predict the converse piezoelectric effect. Quartz and Rochelle salt exhibited the most piezoelectricity. They combined their knowledge of pyroelectricity with their understanding of the underlying crystal structures that gave rise to pyroelectricity to predict crystal behavior, and demonstrated the effect using crystals of tourmaline, quartz, topaz, cane sugar, and Rochelle salt (sodium potassium tartrate tetrahydrate). The first demonstration of the direct piezoelectric effect was in 1880, by the brothers Pierre Curie and Jacques Curie.
Drawing on this knowledge, both René Just Haüy and Antoine César Becquerel posited a relationship between mechanical stress and electric charge however, experiments by both proved inconclusive.
The pyroelectric effect, where a material generates an electric potential in response to a temperature change, was studied by Carolus Linnaeus and Franz Aepinus in the mid-eighteenth century. The effect finds useful applications, such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies. For example, lead zirconate titanate crystals will exhibit a maximum shape change of about 0.1 percent of the original dimension. The piezoelectric effect is reversible in that materials exhibiting the direct piezoelectric effect (the production of electricity when stress is applied) also exhibit the converse piezoelectric effect (the production of stress and/or strain when an electric field is applied).
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