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High Temperature Piezoelectric Ceramics

詳細技術說明

New piezoelectric ceramics have been discovered by researchers working together at Case Western Reserve University and NASA Glenn Research Center that can be used at high temperatures in a variety of

*Abstract

New piezoelectric ceramics have been discovered by researchers working together at Case Western Reserve University and NASA Glenn Research Center that can be used at high temperatures in a variety of actuators and other applications. Even at temperatures exceeding 400 oC, these materials do not depole and retain large piezoelectric coefficients >400 pm/V.In addition, the thickness mode electromechanical coupling coefficient is large, increasing from 0.5 to 0.65 with temperature. The planar electromechanical coefficient is around 0.40 and does not show a significant dependence upon temperature.These materials are highly polarizable with remnant polarization of 50 micro-C/cm2 and are electrically hard with a coercive field above 20 kV/cm at room temperature. They exhibit single crystal-like behavior with square hysteresis loops. These properties provide a piezoelectric ceramic composition that is ideal for stack actuators deployed at high temperatures. Specific applications include use in fuel and gas modulation in jet engines, oil drilling, ultrasonic drilling in hot surfaces, vibration dampening on turbine blades, and energy harvesting on hot and vibrating environments. BackgroundPiezoelectric ceramics produce an electrical charge when a load is applied. Piezoelectric ceramics can also produce force or deformation when an electrical field is applied. The production of an electrical charge is useful in pressure or load sensing applications. The production of force or deformation is useful in microactuators, nanoactuators or piezoelectric motors.Piezoelectric ceramics consist of ferroelectric materials that can have large piezoelectric coefficients and non-ferroelectric piezoelectric materials, such as quartz, that have lower piezoelectric coefficients. Ferroelectric materials include barium titanate, bismuth titanate, lead magnesium niobate, lead metaniobate, lead nickel niobate, lead zirconium, titanates (PZT), lead-lanthanum zirconate titanate (PLZT) and lead magnesium niobium titanate (PMN-PT). Important parameters for piezoelectric ceramics include electromechanical coupling constants, piezoelectric coefficient, dielectric constant (relative permittivity), loss tangent, electrical resistivity, Curie temperature and depoling temperature.

國家/地區

美國