Piezoelectricity Pyroelectricity Kosbay Orynbasar Beknazar Sain
Piezoelectricity
In some crystals there is an electric polarization at stretching and compression. This manifestation of a direct piezoelectric effect. This electricity is what we call the piezoelectricity. Piezoelectric properties can have only ionic crystals which don’t have a center of symmetry.
Most known piezoelectrics: quartz, Seignette salt, barium titanate, etc. . Piezoelectric technique used for manufacturing: the piezoelectric stabilizers and filters, vibration sensors and pressure, pickups, microphones, telephones, ultrasound emitters and etc. There is also a converse piezoelectric effect — emergence of mechanical deformations under the influence of an electric field.
Examples
Usually, the polarization charges are compensated by free surface charges, settled out of the atmosphere. However, when heated balance is disturbed appear on the surface polarization charges. The emergence of such charges is called direct pyroelectric effect.
Pyroelectricity
Definition: Pyroelectricity (from the Greek pyr, fire, and electricity) is the ability of certain materials to generate a temporary voltage when they are heated or cooled
Explanation: Pyroelectricity can be visualized as one side of a triangle, where each corner represents energy states in the crystal: kinetic, electrical and thermal energy. The side between electrical and thermal corners represents the pyroelectric effect and produces no kinetic energy. The side between kinetic and electrical corners represents the piezoelectric effect and produces no heat.
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