1-3-Type piezoelectric composites with three-layer cascade structure

This paper proposes a 1-3-type piezoelectric composite structure based on a three-layer cascade structure, utilizing flexible silicone rubber to promote the thickness vibration mode of piezoelectric ceramics. The sandwiched ceramic layer is adopted to improve the mechanical stability. Based on the uniform field theory, we build a theoretical model for the cascade composite and analyze how the thickness of the sandwiched layer and the volume fraction of the ceramic component affect the performance parameters, including the thickness electromechanical coupling coefficient, the density, the sound velocity and the characteristic impedance. Finite element analysis is employed to evaluate the material and validate the theoretical model. The three-layer cascade piezoelectric composites are fabricated using the “dice-and-fill” technique. The tested results demonstrate that the cascade piezoelectric composite exhibits a concentrated thickness vibration mode, and its thickness electromechanical coupling coefficient is up to 0.71, which is 15.5% higher than that of traditional 1–3 piezoelectric composites. It has great potential in developing promising ultrasonic transducers with high transmitting-receiving response.