Some naturally piezoelectric occurring materials include Berlinite (structurally identical to quartz), cane sugar, quartz, Rochelle salt, topaz, tourmaline, and bone (dry bone exhibits some piezoelectric properties due to the apatite crystals, and the piezoelectric effect is generally thought to act as a biological force sensor). There are many materials, both natural and man-made, that exhibit a range of piezoelectric effects. This intense research resulted in the development of barium titanate and lead zirconate titanate, two materials that had very specific properties suitable for particular applications. Although quartz crystals were the first commercially exploited piezoelectric material and still used in sonar detection applications, scientists kept searching for higher performance materials. Over the next few decades, new piezoelectric materials and new applications for those materials were explored and developed.ĭuring World War II, research groups in the US, Russia and Japan discovered a new class of man-made materials, called ferroelectrics, which exhibited piezoelectric constants many times higher than natural piezoelectric materials. This initial use of piezoelectricity in sonar created intense international developmental interest in piezoelectric devices.
The breakout of World War I marked the introduction of the first practical application for piezoelectric devices, which was the sonar device. Over the next few decades, piezoelectricity remained in the laboratory, something to be experimented on as more work was undertaken to explore the great potential of the piezoelectric effect. Their initial demonstration showed that quartz and Rochelle salt exhibited the most piezoelectricity ability at the time.
By combining their knowledge of pyroelectricity with their understanding of crystal structures and behavior, the Curie brothers demonstrated the first piezoelectric effect by using crystals of tourmaline, quartz, topaz, cane sugar, and Rochelle salt. The direct piezoelectric effect was first seen in 1880, and was initiated by the brothers Pierre and Jacques Curie. The piezoelectric effect also has its use in more mundane applications as well, such as acting as the ignition source for cigarette lighters. It is also the basis of a number of scientific instrumental techniques with atomic resolution, such as scanning probe microscopes (STM, AFM, etc). The piezoelectric effect is very useful within many applications that involve the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies. When reversed, an outer electrical field either stretches or compresses the piezoelectric material. When piezoelectric material is placed under mechanical stress, a shifting of the positive and negative charge centers in the material takes place, which then results in an external electrical field.
One of the unique characteristics of the piezoelectric effect is that it is reversible, meaning that materials exhibiting the direct piezoelectric effect (the generation of electricity when stress is applied) also exhibit the converse piezoelectric effect (the generation of stress when an electric field is applied). The word Piezoelectric is derived from the Greek piezein, which means to squeeze or press, and piezo, which is Greek for “push”. Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress.
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