FEM Analysis of Piezoelectric Resonator Polarization Process

Josef Novák

doi:10.3390/app112412045

Abstract

The polarization of the piezoelectric resonator depends on the direction of the applied electric field. The direction of the applied electric field is determined by the shape of the resonator and the position of the electrodes. In case of resonators with electrodes incompletely covering their bases, an inhomogeneous electric field is generated, which results in an inhomogeneous polarization of the resonator. The resonator will be polarized in some places either in a direction other than the desired one or not polarized at all. The aim of this work is to analyze the polarization process on resonators with electrodes incompletely covering their bases. The physical description is given by the linear piezoelectric equations, the Gaussian equation for the description of the electric field and by Newton’s law of force. On this basis, a FEM model is developed and used to analyze the polarization process. The results of the calculation of the electric field vector distribution are presented. Finally, the areas are identified in which polarization in the desired direction is achieved in the resonator as well as the ones where no polarization occurs.

Highlights

Solid solutions based on PbTiO3 − PbZrO3, referred to as PZT ceramics, or solutions based on BaTiO3 are primarily used for the production of piezoelectric transducers
The efficiency of electromechanical conversion in piezoelectric transducers is assessed by the magnitude of the electromechanical coupling coefficient, which can be generally expressed as Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
We find electrodes in the studied configuration-electrodes are wrapped from one base to another

Summary

Introduction

Solid solutions based on PbTiO3 − PbZrO3, referred to as PZT ceramics, or solutions based on BaTiO3 are primarily used for the production of piezoelectric transducers. The piezoelectric properties of these materials are conditioned by the existence of spontaneous polarization. These samples do not show macroscopic piezoelectric properties after sintering because the directions of polarization in individual grains of the ceramics are different. I.e., after application of a sufficiently strong DC electric field, and usually at increased temperatures, these macroscopically observable piezoelectric properties appear in the transducers. (1) Win. Its square expresses the ratio of the fraction of energy Wout that changes from electric to mechanical or vice versa to the total energy received Win, e.g., [1]. In the case of circular resonators, the polarization field is homogeneous due to the solid electrode and the high permittivity of the piezoelectric ceramics. The polarization is homogeneous over the entire volume of the piezoceramic resonator

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