Fabrication of Piezoelectric PZT Film Actuators on Thin Metal Plates Prepared by a Hydrothermal Method
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0966-T07-01
Fabrication of Piezoelectric PZT Film Actuators on Thin Metal Plates Prepared by a Hydrothermal Method Tsuyoshi Aoki, Shigeyoshi Umemiya, Masaharu Hida, Keisuke Satoh, Masao Kondo, and Kazuaki Kurihara Fujitsu Ltd., Atsugi, 243-0197, Japan
ABSTRACT Hydrothermal lead zirconate titanate (Pb(Zr,Ti)O3: PZT) films with a thickness of about 10 µm on both a Ti foil and a Ti layer sputtered stainless steel foil were obtained. Both PZT films showed same morphology and crystallinity. Each transverse piezoelectric constant (d31) was estimated by a tip displacement measurement with cantilever shape. The d31 value of the PZT films on Ti layer sputtered SS foils is -29 pm/V, which is larger than that on the Ti foil (-24 pm/V). Amorphous layers consist of Pb and Ti were observed at the interfaces between the PZT and the Ti in both films. The thickness of the layer for the PZT film on Ti foil (350 nm) is thicker than that for the film on SS foil (200 nm). The relative permittivity of the amorphous layer is estimated to be small compared with that of PZT. Accordingly, the effective electric field for PZT layer is decreased. The difference of d31 values between the obtained PZT films is thought to be depended on the thickness of the amorphous layer. INTRODUCTION In recent years, wireless communication frequencies (3-6 GHz) are heavily crowded. Most of the frequency bands are occupied by mobile communications, broadcastings and so on. For future wireless broadband network, the effective use of frequency resource is desired. In order to realize the effective use of the frequencies, a cognitive radio in wireless system is proposed [1,2]. The system requires for devices that the precipitous band-pass filtering properties avoiding signal interfering and the wide and fine tunability of outputted signals for assignment to optimum signals. A tunable high temperature superconducting (HTS) filter module is thought to be a leader candidate. A tunable HTS filter module has been proposed and demonstrated [3,4]. The module is composed of a number of HTS resonators. Using the resonators, sharp output signals can be obtained. A schematic illustration of a resonator unit is shown in Fig. 1. The unit has circle resonators and wiring which are consisted of yttrium barium copper oxide (YBa 2 Cu 3 O 7 : YBCO) material formed on a magnesium oxide (MgO) single crystal substrate, and a lanthanum aluminates (LaAlO3: LAO) plate facing the surface of MgO substrate. High-frequency signals propagate on the surface of the YBCO patterns. The electric fluxes are formed continuously from the YBCO pattern to the air gap between the MgO substrate and the dielectric LAO substrate. So, the electric fluxes and the dielectric plate are interfered with each other. Adjusting the air gap enabled the device to tune its resonant frequency. To control the air gap, attachment of piezoelectric thin film unimorph actuators using its deflection is thought to be one of a candidate. In order to obtain large deflection, lead zirconate titanate {Pb(Zr0.52,Ti0.48)O3: PZT(5
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