What’s the polarization process of piezoelectric ceramics

The polarization process of piezo ceramics refers to adding a strong DC electric field to the piezoelectric ceramic to align the domains in the ceramic in the direction of the electric field. Only the ceramics processed by the polarization process can display the piezoelectric effect.

1 polarized electric field

The polarized electric field is the most important factor in the polarization process. The higher the polarization electric field, the larger the effect of the orientation of the domain alignment, and the more sufficient the polarization, the electric field with the maximum value of Kp is generally the polarization electric field.The polarization electric field of piezo cylinder tube transducer must be larger than the coercive field of the sample, usually 2 to 3 times of the coercive field. Taking the common lead zirconate titanate piezoelectric ceramic as an example, the coercive field is generally 800-1200 V/mm, and the polarization electric field is used. Generally take 2000 ~ 3000V / mm.

2 polarization time

After the application of the electric field, the initial polarization of PZT material parameter is mainly the inversion of the 180° domain inside the ceramic, followed by the steering of the 90°domain, and the steering of the 90°domain is difficult to perform due to the internal stress, so the extension is appropriately extended. The time is set, the degree of orientation of the domains is high, and the polarization effect is good. The general polarization time is from 10 min to 50 min.

3 . polarization temperature

Under the condition of polarized electric field and time, the polarization temperature of piezoelectric discs piezoelectric tranducer is high, the orientation of the domain is easy to arrange, and the polarization effect is good. When the temperature is too high, the smaller the electrical resistivity of the ceramic, the lower the compressive strength, and the breakdown of the ceramic body due to the high electric field, damaging the piezoelectric ceramic. Commonly used piezoelectric ceramic materials have a polarization temperature of generally 50°C to 150°C.The polarization electric field, polarization time and polarization temperature must be considered comprehensively. They have mutual influences. The optimal polarization process parameters should be determined through experiments.