Loss Characterization in Single and Polycrystalline Piezoelectrics

We will clarify the macro- and micro-scopic mechanisms of the losses in piezoelectric single crystals and ceramics, aiming at development of high power piezoelectric materials and devices for the Navy's application. This program is composed of three aspects: (1) Loss Phenomenology: Phenomenological formulation in piezoelectric losses (i.e., dielectric, elastic and piezoelectric losses for intensive and extensive parameters) will be considered comprehensively, including new equivalent circuit proposals. Microscopic loss mechanisms will be investigated in piezoelectric single crystals and ceramics with respect to the domain dynamics. From the crystal orientation dependence of loss factors, we will explain the contributions of different domain wall motions to these dielectric, elastic and piezoelectric losses. (2) Characterization Methodology: In addition to the conventional admittance/impedance spectrum analysis, we will establish the Burst Mode characterization technique, aiming at the future IEEE Standard method. In order to facilitate to measure various loss tensor components, we also propose a new piezo-sample configuration (i.e., partial electrode patterns) for determining intensive and extensive losses. (3) Materials: The loss mechanism difference will be explored, in particular, in the conventional PZT's, relaxor:PbTiO3 single crystal ferroelectrics and lead-free materials, with a particular focus on ionic species and dopants, in terms of the internal bias field generated in hard piezoelectric materials, aiming at development of high energy density materials. DC external bias electric field and stress dependence of losses will be another important target of research from a practical application viewpoint.