Abstract:
There is increasing interest in relaxor ferroelectrics such as PMN-PT-La,Ba (lead magnesium niobate-lead titanate doped with lanthanum or barium) for use as high-power transducer driver materials in lightweight projector arrays. These electrostrictive materials have been shown to have induced strains an order of magnitude greater than PZT at modest electric fields. The drawback, however, is that the response of the material is dependent on frequency, prestress, temperature, and ac drive and dc bias fields. To date no measurements have been made of all these relationships for 33-mode vibration applications. In this study, using various mechanical prestresses, quasistatic room temperature measurements were made of the piezoelectric constant, d[inf 33], of the relative permittivity, (epsilon)[inf 33][sup T]/(epsilon)[inf 0], and of the short-circuit Young's modulus, Y[inf 33][sup E] for PMN-PT-La (TRS Ceramics, Inc., 0.90 / 0.10 /1%, 31 March 1995). Electric fields of up to 2 MV/m were applied to samples (2x2x10 mm that were prestressed from 0 to 12 ksi (83 MPa). The material was found to have energy density values comparable to Terfenol-D, but its lower electromechanical coupling may compromise the useful bandwidth. [Work sponsored by the Office of Naval Research.]