Measurements of complex materials constants of piezoelectrics: extensional vibrational mode of a rectangular bar

An iterative, automated method for characterization of piezoelectric specimens of a rectangular bar in the longitudinal extensional mode has been developed. The complex materials constants (dielectric constants, elastic compliance coefficients and piezoelectric constants) of piezoelectric specimens with various Q were accurately determined. A new method to estimate the appropriate initial values of the complex materials constants for a nonlinear iteration process has been presented. This nonlinear iterative fitting procedure was carried out for the experimental admittance spectra Y = G + j B for various specimens with high (4600) or low (50) Q values and the validity of the method was verified.