Determination of the complex material constants of PMN-28%PT piezoelectric single crystals

The accurate characterization of piezoelectric crystals should include the loss properties of the materials, which are represented as the imaginary parts of the material constants. The full complex properties of PMN-PT single crystals have never been evaluated. This paper proposes an automated iterative method to determine the complex material constants of PMN-28%PT single crystals. The PMN-28%PT single crystals were grown using the Bridgman method and were poled along the [001] direction to have 4mm effective symmetry. Five different resonators suitable for 4mm symmetry were used to analyze the impedance and admittance spectra of the distinctive resonant modes. The complex material constants were determined by the nonlinear regression of the impedance and admittance spectrum equations for each resonator through the iteration process to fit the measured spectra of the corresponding modes. The efficacy of the characterization method and the accuracy of the complex material constants determined using this method were verified by a comparison of the immittance spectra from the measurements with those from the calculation using the complex constants.