In Converse piezoelectric effect, application of an electrical field creates mechanical deformation in the crystal. When a mechanical stress is applied, this symmetry is disturbed, and the charge asymmetry generates a voltage across the material. The domains are usually randomly oriented, but can be aligned during poling, a process by which a strong electric field is applied across the material, usually at elevated temperatures. Each of these sides forms an electric dipole and dipoles near each other tend to be aligned in regions called “Weiss domains”. This makes the crystal electrically neutral. In a piezoelectric crystal, the positive and negative electrical charges are separated, but symmetrically distributed. It is also the basis of a number of scientific instrumental techniques with atomic resolution, the scanning probe microscopies and everyday uses such as acting as the ignition source for cigarette lighters and push-start propane barbecues. The Piezo effect finds many applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies. The most common crystals used is lead zirconate titanate crystals. Direct piezo electric effect is the production of electricity when the crystals are mechanically stressed and the converse piezo electric effect is the stress or strain in the crystals when an electric potential is applied. The piezo material exhibits both “Direct piezo electric effect” as well as ‘Converse piezo electric effect”. The word Piezo is derived from the Greek “Piezein”, which means to squeeze or press. If the piezo crystals are not short-circuited, the applied charge induces a voltage across the material. Piezoelectricity is the ability of some materials such as crystals and certain ceramics, to generate an electric potential in response to applied mechanical stress or heat.
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