Determination of full set material constants of piezoceramics from phase velocities

The determination of elastic and piezoelectric constants by means of the resonance method is described in detail in the Institute of Electrical and Electronics Engineers Standards. However, in practice, it is not easy to obtain a self-consistent complete set of elastic and piezoelectric coefficients using the resonance method alone, since the geometric requirements are often too difficult to meet in some materials and property variation from sample to sample could be substantial. In this article, we report on a characterization scheme by regression of ultrasonic velocities in different directions. The method using the Levenberg-Marquardt algorithm is very stable. Only two samples are needed to determine the whole set of the material constants. The method has been applied to doped piezoceramic lead zirconate titanate and material constants obtained at the same frequency show excellent self-consistency.