Kazuyasu Hikita

Piezoelectric properties of the porous PZT and the porous PZT composite with silicone rubber

Abstract Interconnected porous Pb (Zr0.53 Ti0.47)O3 ceramics, with controlled porosity up to 0.73, were prepared. The piezoelectric coefficient, 933, measured using a resonant method and a Berlincourt d33 meter increased as the porosity increased. The d33 and 933 of the porous PZT ceramic/ silicone rubber composite were almost the same as that of porous PZT.

Effect of Porous Structure to Piezoelectric Properties of PZT Ceramics

Porous Pb(Zr0.53 Ti0.47)O3 ceramics with three dimensionally interconnected structure were prepared by modifications of conventional powder sintering methods. The piezoelectric and elastic properties of the porous PZT were investigated by related with pore structures such as porosity and pore size. As porosity increased, permittivity decreased linearly and piezoelectric coefficient d33 increased gradually, so the voltage output coefficient g33 increased. The g33 value was 200–300×10-3 (Vm/N) at the porosity of 0.65.

Mode of occurrence and cause of cracking of Li2B4O7 single crystals during growth by Czochralski method

The mode of occurrence and the origin of cracking of lithium tetraborate (Li2B4O7) single crystals during growth have been investigated. The melt temperature dependence and the origin of crystal cracking have been explained in terms of activation enthalpy change for viscous flow in Li2B4O7 melt associated with temperature distribution in the melt.

Dependence of electro-optic properties of PLZT upon the chemical compositions

Abstract The characteristics of the ferroelectric and the electro-optic properties was investigated on the transparent PLZT ceramics, which had a slim D-E loop. The coercive force Ec was 0.24 × 106 V/m and the remnant polarization Pr was 7.9 × 10−2 C/m2 for the typical composition of PLZT (9/65/35), applying AC 2 kV/mm at 50 Hz. Transmittance of a PLZT electro-optic shutter was studied. The shutter was fabricated by PLZT wafer with a pair of slot electrode sandwiched between artificial polarizers under crossed Nicols. In order to evaluate the electro-optic hysteresis, the ratio of the half width to the applied voltage was employed, and was about 20% for PLZT (9/65/35), 13% for PLZT (10/65/35) and 8% for PLZT (9/69/31), in giving the maximum light intensity. The hysteresis of transmittance were decreased with increment of both La and Zr content, although the quadratic electro-optic coefficient was decreased.

All-Optical Control Devices Utilizing Bulk Photovoltaic Effect

Some ferroelectrics such as PLZT with impurity dopants induce a high voltage under near-ultraviolet radiation. It was found that donor-type dopants situated onto the B-site of the perovskite structure enhance this photovoltaic response in PLZT ceramics. Using a donor-doped photovoltaic PLZT(3/52/48) plate with a transparent electrooptic PLZT(9/65/35) chip mounted, all optical control devices, modulators and deflectors, have been trial constructed.

Tuning of a surface acoustic wave resonator formed of lithium tetraborate substrate combined with piezoelectric ceramic element

Tuning of resonant characteristics, especially of resonant frequency, was studied on surface acoustic wave resonator, which was formed on a lithium tetraborate substrate and adhered to a poled piezoelectric ceramic element. The resonant frequency was tunable when a electric field (up to 1.5 kV/mm) was applied to the piezoelectric element. The magnitude of resonant frequency tunining was about 600 ppm, so that the temperature coefficient of resonant frequency change could be tuned to be constant or almost zero ppm/°C over the experimental temperature range between 0 and 75°C. The mechanism of tuning is considered to be that the distance between interdigital electrodes on the resonator was changed as the piezoelectric ceramic element was actuated and deformed with the application of electric field.

Enhancement of Optical Wave Mixing Characteristics of Photorefractive Bi12SiO20 Crystal by Moving Grating Method

The moving grating method was applied to a photorefractive Bi 12 SiO 20 crystal in order to enhance the light amplification factor γ 0 in the two-wave mixing process and the reflectivity R of the phase conjugate wave in the four-wave mixing process. It was found that γ 0 and R exhibited maximum values when the interference pattern moved inside the Bi 12 SiO 20 crystal at an optimum velocity. We achieved 65% reflectivity of the phase conjugate wave at that velocity. The response time of the photoinduced refractive index grating was determined with varying incident beam intensity, external electric field and grating spacing