Estimation of Certain Material Properties of a 1-3 Piezoelectric Composite as Functions of Temperature, Uni-Axial Stress and Electric Field

Abstract

A method to estimate certain material properties of a 1-3 piezoelectric composite from the electrical impedance spectra, measured as functions of temperature, uni-axial stress and applied electric field, is proposed. A theoretical model is formulated to determine the impedance of lossy piezocomposite plates vibrating in the thickness-mode using complex material parameters. The impedance data are least-squares fitted to the model, and the relevant dielectric, mechanical and piezoelectric parameters are first determined by regression analysis and then refined by iteration. Good agreement between the theoretical impedance spectra with the measured spectra validates the method. The complex material parameters and the device parameters are found to vary non-linearly with variations in temperature, stress and electric field. This type of characterisation is important to understand and predict the behaviour of transducers that are subjected to varied environmental conditions and are driven at high electric fields during operation.