High frequency properties of piezoceramic resonators

Several methods of calculating the material properties of thickness mode resonators from electrical impedance measurements have been studied. A method accurate at frequencies up to 100 MHz has been used to measure the properties of several commercially available PZT compositions over the frequency range of from 5 to 100 MHz. New materials with sub micron grain sizes have also been evaluated and found to have properties less dependent on frequency. A commercial lead titanate material was evaluated and found to have properties comparable to PZT, but with a much lower dielectric constant. The dielectric permittivity of a material is shown to be particularly important in determining transducer performance due to electrical matching