Piezoelectricity

Abstract Certain materials produce electrical charges on their surfaces as a consequence of applied mechanical stress. The induced charges are proportional to the mechanical stress. This is called the direct piezoelectric effect and was discovered by Jacques and Pierre Curie in 1880. Materials showing this phenomenon also conversely have a geometric strain proportional to an applied electric field. This is the converse piezoelectric effect. The root of the word “piezo” means “pressure”; hence, the original meaning of the piezoelectricity implied “pressure electricity.” Piezoelectric materials provide coupling between electrical and mechanical parameters. The material used earliest for its piezoelectric properties was single‐crystal quartz. Quartz crystal resonators for frequency control appear today at the heart of clocks and are also used in computers and mobile phones. Ferroelectric polycrystalline ceramics such as barium titanate and lead zirconate titanate exhibit piezoelectricity when electrically poled. Since these ceramics possess significant and stable piezoelectric effects, that is, high electromechanical coupling, they are capable of producing large strains/forces and hence are extensively used as transducers. Piezoelectric polymers, notably polyvinylidene difluoride and its copolymers with trifluoroethylene and piezoelectric composites combining a piezoelectric ceramic with a passive polymer, have been developed that offer a high potential. Thin films of piezoelectric materials have received attention recently because of their potential utilization in microsensors and ‐actuators. Piezoelectricity is being extensively utilized in the fabrication of various devices such as transducers, actuators, surface acoustic wave devices, and frequency control. In this article, we discuss the piezoelectric effect, a brief history of piezoelectricity followed by present‐day piezoelectric materials that are used, and finally various potential applications of piezoelectric materials.