Piezo Effect of PZT Piezoelectric Ceramic Material

For a 90 degree, the ultrasonic atomizing piezoelectric may move sideways, and the critical electric field needed for the lateral movement of the 90° is smaller than the critical electric field that is required for the new wedge-shaped domain. However, for a 90°to be steered to the direction of the external electric field, Piezoceramic materials consistency requires a large electric field, the development of its new domain is mainly driven by the external electric field 90°lateral movement of domain walls. Under the condition of t = 15 min and T = 130℃, the polarization of piezoelectric circuit piezoelectric ceramic was changed by changing E, and the variation of piezoelectric constant d33 with E was obtained. When E <1.5 kV / mm, When E> 1.5 kV / mm, d33 increases rapidly with the increase of E, but when E> 2.5 kV / mm, d33 suddenly and rapidly decreases. This is because when piezoelectric transducer materials E <1. 5 kV / mm, the polarization can only make the material easy to orient 180 degree to the direction of the external electric field, so the value of d33 is lower and increases more slowly; when E> 1.5 kV / mm, the external electric field is larger than the coercive field of the material, which makes the 90°electric field, which is difficult to turn, pickup piezo transducer tends to the direction of the external electric field, so the d33 increases rapidly; which continue to increase the electric field strength, when E> 2.0 kV / mm, the piezoelectric domain in the material turns to almost complete, so the increase of d33 tends to be slow.However, when E reaches a certain value (E> 2.5 kV / mm), the free energy in the electric field obtained by the free electrons in the ceramic exceeds the energy lost, and according to the ionization collision theory, free electrons can be released after each collision Accumulation of energy,Thermoelectric transducer piezo is leading to the ceramic sheet temperature continues to rise, the piezoelectric properties continue to decline, the final thermal breakdown. Moreover, when the applied electric field is high enough, the forbidden band electrons may enter the conduction band due to the tunneling effect of quantum mechanics. Under the action of a strong field, free electrons are accelerated to cause electron impact ionization. At this time due to the current increases, the local temperature of the crystal increases, leading to partial melting of the crystal and its destruction of the structure, so that the piezoelectric properties of ceramics decreased, the final breakdown will occur.