Toshihiko Kittaka

Energy trapping characteristics of the second harmonic thickness extensional vibration in a two-layered monolithic piezoelectric plate

Energy trapping characteristics of two-layered piezoelectric ceramic resonators hae been studied around their second-harmonic thickness-extensional vibration. The vibration was excited through external and internal electrodes; the latter was prepared in a monolithic plate utilizing the common process of manufacturing multilayered monolithic capacitors. The energy trapping of the frequency-lowering-type was observed in agreement with the calculation. If the unelectroded region is not polarized, energy trapping is not sufficiently realized because of its slight frequency-lowering. When the inner electrode is not placed at the middle of thickness, levels of the resonance response are dependent on harmonic order of the vibration.

Displacement Characteristics of Series-Type Bimorph Actuator under High Applied Voltage

Experimental and theoretical studies on the applied voltage-displacement characteristics of a piezoelectric series type bimorph were performed. The displacement increased with an increase in the applied voltage until dielectric breakdown. An electric field higher than its coercive field (Ec) can be applied to the bimorph, because its poling direction is opposite to the field, owing to an electric charge balance between its two layers. On the other hand, the displacement of a parallel-type bimorph fell to zero when the applied voltage per unit length equalled Ec. The series-type bimorph displayed larger displacement and higher reliability than the parallel-type bimorph.

Electrical and Mechanical Properties of Pb(Zr, Ti)O3 Ceramics Related to Mn Ion Diffusion

The electrical and mechanical properties of Pb(Zr, Ti)O3 (PZT) ceramics with Mn ions injected by diffusion at high temperature were studied. The rise of mechanical quality factor (Qm) and the change of fracture mechanism from intergranular fracture to transgranular fracture was observed with increased diffusion temperature. These changes are related to the diffusion of Mn ions from the grain boundaries into the grains.

Finite Element Analysis of Energy-Trapped Second Harmonic Thickness Extensional Vibration

A second harmonic mode in a piezoelectric plate with an internal electrode is analyzed by means of the finite element method. This paper shows that although energy-trapping cannot be realized in a PbTiO3 piezoelectric plate for a fundamental mode, it is possible for a second mode.