Measurement of the real and imaginary piezoelectric, elastic, and dielectric constants for dispersive piezoelectric transducer materials

The recent past has seen the introduction of many new types of piezoelectric materials with relatively high dissipation and low mechanical Q (PVDF, ceramic–polymer composites). In order for designers to predict the performance of these materials in transducers, the imaginary components of the dielectric, elastic, and piezoelectric constants need to be known. This is typically done by analyzing the electrical impedance spectra and applying the methods described in the IEEE standard on piezoelectricity [IEEE Std. 176‐1987] to calculate the relevant material constants. This paper describes new methods of analysis that expand on the IEEE standard and allow the experimenter to analyze materials with low mechanical Q and substantial piezoelectric loss factors. The paper also describes a technique to determine dispersion in the material constants from the experimental impedance or admittance spectra of the materials. [Work supported by DREA, DND‐Canada.]