Study on air Polarization of KNN Piezoelectric Ceramics

Polarization treatment plays a crucial role in determining the electrical properties of piezoelectric ceramics. In order to clarify the optimal polarization conditions required for piezoelectric devices, the influence of different polarization conditions on piezoelectric ceramics is discussed, which may be an important condition for improving their piezoelectricity and dielectricity. In this paper, vacuum hot-pressure sintering method is used to prepare potassium sodium niobate (KNN) piezoelectric ceramics. The experiment adopts control variable method to design the scheme of air polarization and high temperature polarization of KNN piezoelectric ceramics. After air polarization, with the increasing of polarization temperature, the piezoelectric constant first increases and then gradually decreases. The dielectric constant decreases then increases. The phase angle first increases then tends to be constant and finally decreases. The electromechanical coupling coefficient increases slowly. Compared with air polarization, the electromechanical coupling coefficient of KNN piezoelectric ceramics have been obviously increased after high temperature polarization.