Piezoelectric Materials MEEN 3344 Edward L. Gamino September 21, 2009

Types Quartz- first commonly used crystal Lead Zirconate PZT-most common ceramic in use today Rochelle salt Cane sugar Bone                                           

Piezoelectric Effect The piezoelectric effect was discovered in 1880 by brothers Jacques and Pierre Curie. They discovered that when a mechanical stress was applied on crystals (such as tourmaline, topaz, quartz, Rochelle salt and cane sugar) electrical charges appeared, and the voltage was proportional to the amount of stress. An everyday application example is a car's airbag sensor. The material detects the intensity of the shock (impact) and sends an electrical signal which triggers the airbag to deploy.

How Piezoelectricity Works Example : In a relaxed state with no forces acting on the positive or negative charges, they are arranged at the vertices of a hexagon.  The positive and negative configuration of charges will cancel each other out and the potential Voltage, a distance along the x axes will be zero.                                 If a compressive force (mechanical stress or stress) is applied to the hexagon along the Y axes direction, the configuration is distorted to bring two of the positive charges closer together at one end and the negative charges at the other.  This forms a dipole where one end of the structure is positive and the other negative. Voltage at a distance along the X axes will now be present.  This process is also reversible.                                                  

Applications Sonar-first practical application Vibration Dampeners Phonographs Transducers Airbag sensor Lighters Printers Cell Phones

References Callister, William D, and David G. Rethwisch. Fundamentals of Materials Science and Engineering. New York: Wiley, 2008. Jaffe, Bernard, William Cook, Hans Jaffe. Piezoelectric Ceramics. New York: Gould, 1971 Buchacz, A. ”Piezoelectric layer modeling by equivalent circuit and graph method.” Journal of Achievements in Materials and Manufacturing Engineering 20 (2007). Homepage. Piezoelectric Materials. http://www.piezomaterials.com/index.htm Homepage. Piezoelectricity. http://www.tedlind.net/Piezoelectricity.htm