Effect of polarized electric field on piezoelectric property is during the polarization process, the polarized electric field of piezo discs and cylinders is the external driving force for the electric domain to turn. Under the condition of no exceeding field strength of the material, the E is the larger, the more the electric field is oriented ,the effect is the greater , the more is to complete the polarization and the better is the piezoelectric properties. which are difficult to deflect or reorient at low pressure, more piezo disc element
is prone to deflect or reorient under high pressure, resulting more complete polarization. For a 180°inversion domain, the inversion of the piezo transducer sound
does not result from the lateral movement to divert the opposite domains, but instead produces many polarizations inside the inversion domain near the electrode.The direction and the electric field direction of the wedge-shaped is new , the new domain nucleation after the electric field is to move forward, penetrating the entire sample. As the electric field increases, piezo transducer for humidifier
continue to emerge and continue to propagate throughout the reverse domain. Eventually, the reverse domain becomes consistent with the direction of the external electric field and combines with the adjacent domains to form a larger volume Similar to the domain.For a 90°domain, the domain walls may move sideways, and the critical electric field of piezoelectric disc generator
is required for lateral movement at 90°is smaller than the critical electric field required for a new wedge-shaped domain. However, if 90°steering is consistent with the direction of the external electric field .A larger electric field of soldering piezo discs is required. The development of new domains mainly depends on the external electric field to promote the lateral movement of the 90°wall. Under the conditions of t = 15 min and T = 130 ℃, the polarization of piezoelectric ceramic was changed by E, and the variation of piezoelectric constant d33 with E was obtained. When E is <1. 5 kV / mm, d33 increases slowly with the increase of E; when E is > 1.5 kV / mm, d33 increases rapidly with the increase of E, but when E> 2 5 kV / mm, d33 suddenly and rapidly dropped. This is because when E is <1. 5 kV / mm, the polarization of piezo disc datasheet can only make the material easy to orient 180°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, tends to the direction of the external electric field, so the d33 increases rapidly; cylindrical piezoelectric transducer continues to increase the external 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,piezoelectric knock sensor 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.