J. Phys. IV France 128 (2005) 161-167
DOI: 10.1051/jp4:2005128025

Frequency dependance of electromechanical properties of PZN-xPT single crystals

T. Delaunay¹, E. Le Clézio¹, H. Dammak², P. Gaucher², M. Pham Thi³, M. Lethiecq¹ and G. Feuillard<sup>1

1</sup>  LUSSI - GIP Ultrasons, Université François Rabelais, FRE 2448 CNRS, EIVL rue de la Chocolaterie, BP. 3410, 41034 Blois Cedex, France
²  SPMS, École Centrale Paris, Grande Voie des Vignes, 92295 Chatenay Malabry Cedex, France
³  THALES Research & Technology-France, Ceramics & Packaging Department, Domaine de Corbeville, 91404 Orsay Cedex, France

Abstract
In this paper, the frequency behaviour of electro-mechanical properties of PZN-xPT single crystals with compositions close to the morphotropic phase boundary is studied at frequencies up to 100 MHz. Properties are deduced from the fit of the electrical input impedance, theoretically calculated with the KLM equivalent circuit model, to experimental data. To measure the electrical impedance of a crystal, its surfaces have first to be metallized. For very thin samples, this metallization may influence the resonances and alter the property identification. A theoretical study is thus performed to quantify the influence of the electrodes on the crystal vibrations. The results show that, even for high frequencies, their effects are negligible. In a second part, the evolution with frequency of the single crystal characteristics is studied. The properties are obtained in a frequency bandwidth centered on the resonances, from the fundamental to the 21 harmonic. The study shows the stability of the electromechanical properties versus the frequency. Finally, the mechanical and dielectric loss tangents are quantified.

© EDP Sciences 2005