Whisker Reinforced Piezoelectric Ceramic Transducer Material

Abstract

The present paper concerns the successful production of whisker-reinforced composites of the piezoelectric ceramic type. Specific results are presented concerning the composite properties of α-Alumina (sapphire) whiskers in a lead zirconate titanate matrix. Other whisker and matrix materials are briefly discussed. In general, the process of adding whiskers to the piezoelectric matrix results in a new material with somewhat different properties, yet one that remains piezoelectric. Specific details discussed include the measurement of dielectric constant, dielectric loss tangent, electromechanical coupling factor, mechanical Q, density, and modulus for a number of whiskered piezoelectric samples. Data on appropriate parameters are presented as a function of temperature over a wide range. The indication is that the addition of whiskers to the material pins the domains so that a “harder” material is produced. The result is a higher Curie temperature for the composite than the matrix alone, a higher poling temperature, a lower dielectric constant, and other related changes. The activation energy for domain wall motion is determined for the matrix material but gives difficulties in the composite case. [Supported by the Office of Naval Research.]