Masaharu Hida

Piezoelectric Properties of PbNi1/3Nb2/3O3–PbTiO3–PbZrO3 Ceramics

The longitudinal electromechanical coupling factor (k33) was investigated as a function of PbNi1/3Nb2/3O3– PbTiO3–PbZrO3 (PNN-PT-PZ) piezoelectric ceramic compositions close to the morphotropic phase boundary (MPB). The k33 was influenced by the grain size of PNN-PT-PZ ceramics. The composition of the MPB determined by k33 is slightly different from that of the free permittivity. The maximum value of k33 in PNN-PT-PZ system attained to 0.8 on the composition of 0.5PNN-0.345PT-0.155PZ.

Rotating Symmetrical Piezoelectric Microactuators for Magnetic Head Drives

A unique piezoelectric microactuator for the head-slider drive dual-stage actuator systems in magnetic disk drives has been developed. This microactuator is based on a rotating symmetrical structure and a symmetrical operation. The piezoelectric actuator elements used in the system have a simple rectangular multilayered structure. A prototype model with pico slider and head suspension has been tested to demonstrate 0.86 µm displacement at a dc applied voltage of 30 V and observed main resonant frequency of over 20 kHz. No fluctuation in flying height was observed.

Piezoelectric Properties of PZT Film Prepared by Chemical Solution Deposition Method

The influence of the stress and orientation of a lead zirconate titanate (PZT) film on its piezoelectric properties was investigated. Preferentially (111) oriented PZT films were prepared on various substrates with different thermal expansion coefficient, such as stainless steel, alumina, magnesia, and silicon by the CSD method. Preferentially (100) oriented PZT films were also prepared on stainless steel. The displacements of cantilevers of the PZT films with the substrates were measured by the laser Doppler vibration method, and the d31 piezoelectric coefficient was calculated from the displacement. Compressive stress degraded the d31 piezoelectric coefficient of (111) oriented PZT film. In the PZT film with compressive stress, the change of orientation to the (100) direction effectively improved the d31 coefficient. An excellent piezoelectric coefficient (d31 = 55 pm/V) of PZT film was obtained on the stainless steel substrate.

Piezoelectric Microactuators for Use in Magnetic Disk Drives

A head-slider drive dual-stage microactuator system for use in magnetic disk drives was developed. This microactuator system has a symmetrical structure and operation, and utilizes simple rectangular multilayered piezoelectric actuator devices. A prototype model with a pico slider and head suspension was tested and demonstrated. It exhibited a 0.8 µm displacement at a dc applied voltage of 30 V and a fundamental resonant frequency of over 20 kHz.

Measurement of d15 Shear-Mode Piezoelectric Response in PZT Thin Film

Piezoelectric films using d15 shear-mode can be applied to many useful MEMS devices. The small displacement derived from the d15 shear-mode was directly observed by a SPM measurement. An isolated PZT(52/48) active part having a pair of driving Cu electrodes was processed in a 5 m-thick sputtering film. The displacement measurement of the active part and its FEM analysis suggested that the estimated d15 piezoelectric constant of the film was 590 pm/V. And, the d31 value of the film was -120 pm/V measured by a conventional cantilever method. The obtained piezoelectric constants of the PZT film are near those of bulk.

Characterization of (Bi,La) 4 Ti 3 O 12 (BLT) Thin Films Fabricated by Low Temperature Sol-Gel Synthesis

The effect of excess Bi content on (Bi,La) 4 Ti 3 O 12 (BLT) thin film fabricated by sol-gel synthesis was investigated. The films were formed on Pt/IrO 2 /SiO 2 /Si. Excess Bi promoted the formation of a secondary phase around BLT particles during the crystallization process, and this secondary phase promoted the crystallization and grain growth of the film and improved its ferroelectric properties. A BLT thin film crystallized at 600°C had good ferroelectric properties: its remanent polarization was 26.2 w C/cm 2 and its coercive field was 53.1 KV/cm. After 10 9 switching cycles, its remanent polarization had decreased less than 10%.

Piezoelectric properties and phase transitions of PbNi/sub 1/3/Nb/sub 2/3/O/sub 3/-PbTiO/sub 3/-PbZrO/sub 3/ ceramics

In this study, the phase transition behavior of PbNi/sub 1/3/Nb/sub 2/3/O/sub 3/-PbTiO/sub 3/-PbZrO/sub 3/ (PNN-PT-PZ) ceramics was investigated. Dielectric properties in PNN-PT-PZ ceramics with the compositions near morphotropic phase boundary (MPB) are studied as a function of temperature. The ceramics with tetragonal phase at room temperature only have a phase transition from tetragonal to cubic with elevated temperature. The ceramics with rhombohedral phase at room temperature show the phase transitions from rhombohedral to tetragonal and from tetragonal to cubic with the increase of temperature. The studies revealed the MPB has a curvature. The large longitudinal electromechanical coupling coefficient (k/sub 33/=0.8) is obtained in the composition along the curvature.