Table of contents

PbTiO₃ thin films have been prepared by rf sputtering under bias application to the substate. Relationships of the plasma potential to the bias voltage have been discussed. Some of the thin films prepared under the substrate bias are highly-oriented and the dielectric properties become better with increase of the bias voltage. The film surface is very smooth because the deposition rate of the horizontal face is high but the inclined plane is etched off very much.

PbTiO₃ thin films were deposited by thermal decomposition of organometallic compounds and their electrical properties were studied. The dielectric constant of these films was estimated to be about 200. D–E hysteresis loops were observed in the films deposited on Pt plates. Remanent polarization and coersive force were about 37µC/cm² and 130 kV/cm, respectively. Measured pyroelectric coefficient (dPr/dT) after applying a field of 150 kV/cm was 1×10^-8 C·cm^-2·K^-1.

Lead titanate (PbTiO₃) thin films are successfully sputter-deposited onto (100)MgAl₂O₄/(100)Si substrates at 480–550°C sputtering temperatures. It is confirmed, from X-ray and electron diffraction analyses, that the PbTiO₃ films grow epitaxially on MgAl₂O₄ films. The crystal properties of PbTiO₃ films depend on those of MgAl₂O₄ films strongly. The PbTiO₃ films are composed of c-axis and a-axis oriented domains. The ratio of the c-axis oriented domain to the a-axis oriented domain is controllable by the cooling rate of the substrate. The dielectric constant of the PbTiO₃ film is estimated to be about 100, based on C-V measurements with a metal-insulator-semiconductor structure.

A reactive multi-target sputtering method was applied to prepare epitaxial (Pb, La)TiO₃ thin films on sapphire. The individual control of each sputtering target revealed that the incident Pb content remarkably influenced the quality of thin film. The strict control of (Pb, La)TiO₃ composition was carried out and strong electro-optic effect was observed in (Pb_0.74La_0.26)Ti_0.94 O₃ thin film.

When amorphous BaTiO₃ thin film is heat-treated, the resultant angle of diffraction is about 0.4° (2θ) lower than the position for ceramic BaTiO₃. The low value of the angle of diffraction is considered to be due to the presence of the platinum substrate. A diffraction line for BaWO₄ has also been observed. These crystals are originally compounds of tungsten and barium with uniform distributions which have been subsequently heat-treated. The BaWO₄ crystals gather in narrow bands when the heat-treatment temperature is higher than 1000°C. At 1400°C, the narrow bands divide into grains with diameters greater than 10 µm, and 85% of the surface areas are composed of BaTiO₃ crystal with an impurity content of less than 3W%. The dielectric constant is therefore found to increase in value.

Perovskite SrMoO₃ thin films are prepared by RF magnetron sputtering at substrate temperatures above 600°C. They show metallic conduction, and their resistivity at 300 K is (1.5∼1.8)×10^-4Ω·cm. The tri-layered capacitor fabricated from SrMoO₃ (base electrode) –SrTiO₃ (dielectric layer)–Cu (counter electrode) has a capacitance of about 0.8 µF/cm² at 1 kHz and 30°C, where the thickness of the SrTiO₃ layer is 700Å.

Crystallized Ta₂O₅ thin film have been deposited on fused quartz substrate by reactive dc diode sputtering. Crystalline structure and piezoelectric properties of the Ta₂O₅ thin film were investigated. Surface acoustic wave (SAW) properties, including a phase velocity, a coupling coefficient, a temperature coefficient of delay, and a propagation loss, were measured for SAW propagating in the Ta₂O₅ thin film on fused quartz substrate. The coupling coefficient K² is 0.7% for hk=1.6. The first-order temperature coefficient of delay time is zero for hk=1.78.

Using Zn metal disk target, ZnO films were prepared in Ar+O₂ mixed gas by both DC planar magnetron sputtering and RF diode sputtering. The dependence of c-axis orientation of ZnO film on O₂ partial pressure was examined from the view point of the bombardment of film by energetic oxygen atoms. For DC planar magnetron sputtering, the c-axis orientation of film does not depend on the O₂ partial pressure, but for RF diode sputtering, the c-axis orientation becomes high at r=10–20%, where r is the percent ratio of O₂ partial pressure to total pressure. It is found that there exists a correlation between the dependence of c-axis orientation on O₂ partial pressure and the film bombardment by energetic O atoms.

Amorphous PbTiO₃ films were prepared by a sputtering deposition. The film deposited on a substrate at 200°C was amorphous. The amorphous PbTiO₃ changed to perovskite PbTiO₃ when it was annealed above the crystallization temperature (520°C). When the amorphous PbTiO₃ was annealed below the crystallization temperature, it partially crystallized and contained pyrochjore and perovskite crystallites. It is considered that the perovskite PbTiO₃ crystallites, which grow in the sputtering-deposited amorphous PbTiO₃ film, are in a "stress-free state" below the crystallization temperature.

Amorphous ribbons of (BaO)_1-x·(TiO₂)_x are prepared by rapid quenching method using a twin-roller apparatus. Transparent ribbon-like thin samples are obtained for the composition range 0.60≦x≦0.75. For as-quenched samples with composition 0.55≦x≦0.80, exothermic peaks in DTA curves are clearly observed at 600–820°C. The dielectric constant for each amorphous sample is about 25 at room temperature, and independent of compositional change. Changes in dielectric behavior of quenched samples with x=0.68 by heat treatment are also discussed.

Rapid-colled amorphous specimens with composition 3/8 and 1/7 in the Li₂O–GeO₂ system have been investigated. The crystallization occurs twice successively in 1/7. Crystallization temperatures rise with increasing heating-rate in DTA-measurement, and the Kissinger analysis enables us to estimate activation energies for the crystallization. The sound velocity was measured at various temperatures with time and the temperature dependence of relaxation time permits us to evaluate an activation energy for the nucleation of crystallites.

Optical properties of ferroelectric liquid crystals have been studied in the infrared range. It is revealed that the electrooptic effects in these ferroelectric liquid crystals can be used successfully in the infrared range (∼15µm) for the application in optical communication and sensing etc.

Visual observations of a chiral smectic C phase were made simultaneously with the measurement of the spontaneous polarization to understand the relation between the stripe pattern (the surface disclination) and the polarization reversal process. The polarization reverse is not directly related to the dynamical change of the stripe pattern. During the polarization reverse, the bright and chaotic pattern were observed independent of the stripe pattern.

Three different methods were used to measure the spontaneous polarization P_s and the coercieve field E_c in a thick cell of DOBAMBC, i.e. polarization reversal current method using a triangular wave, ac method by Pepinsky bridge and dc bias method. P_s obtained from the methods of the former two was typically about 3 nC/cm² and that from dc bias method ∼0.6 nC/cm², which show the bulk and the surface spontaneous polarization respectively. Accordingly the former two can be selectively used to study the bulk properties. Another one is more advantageous to observe the surface dielectric properties.

Some ferroelectric properties, especially spontanious polarization directions and phase diagram of (R)-DOBA-1-MBC, (S) and (R)-DOBA-1-MPC and (S)-HDOBAMBC , have been examined. Relation between spontaneous polarization direction and molecular structure have been discussed.

Switching times rise time, decay time and memory time, of various electro-optic effects in ferroelectric liquid crystals are found to be strongly dependent on the molecular structure, cell thickness and temperatures. Especially in TSM (transient scattering mode) operation, the rise time becomes shorter in liquid crystals with larger spontaneous polarization, at high temperatures and in thinner cell. The decay time is also shorter at higher temperatures, in thinner cells and also in materials with higher relaxation frequency of dielectric constant.

Characteristics of ferroelctric liquid crystals mixed with dichroic dyes are studied by the application of a dc voltage and voltage pulse trains to understand the fundamental processes as a high speed colour switching element. The guesthost effect and its combined effect with the transient light scattering are observed in ferroelectric liquid crystals. The response speed does not change by the introduction of dichroic dyes. The contrast as the optical switching element of the transient scattering mode has been found to increase by the introduction of dichroic dyes.

Zinc oxide single crystals of high purity have been grown by the hydrothermal method adding a partial pressure of oxygen and using platinum-lined autoclave and ultra-pure nutrient reagents. The Stoichiometric assessment of the grown crystals was investigated by empoloying a coulometric analysis which was available for detecting a small deviation in the Stoichiometric constituent, such as Zn_1+xO. The concentration of the excess Zn atoms was accurately determined from 0.8 to 1.7 ppm and the electrical resistivity of the as-grown crystals obtained in the order of 10⁸Ω-cm.

A good quality single crystal of Li₂B₄O₇, up to 23 mm in diameter and 80 mm in length, has been successfully grown at a crystal pulling rate of 1 mm/h and the seed rotation rate of 6 r.p.m. by an automatic diameter control (ADC) of the Czochralski method. This crystal was very transparent and colourless, and possessed large regions free of any optical in homogeneity. Macroscopic defects such as cores appeared in some growing crystals have been discussed. Cores generated in growing crystals largely depended on the crystal pulling rate, rapid temperature change during the crystal growth and purity of starting materials.

All 8 electrostrictive and all 3 third-order dielectric constants of lithium niobate have been determined. Measurements for the electrostrictive constants have been made by measuring electric capacity in selected direction when the directed static stresses were applied to the crystal. And the third-order dielectric constants have been calculated from these measured electrostrictive constants and the measured capacitance as a function of the applied static electric field. All of these measurements have been done at 15°C.

For Fe-doped lithium niobate crystal (LN:Fe 0.1 wt%) grown by Czochralski technique, the effects of oxidation and reduction state were investigated on the photoinduced birefringence change by Ar-laser irradiation (488.0 nm). (1) A high accuracy apparatus for the measurement of the birefringence change has been developed (Sénarmont method). (2) In LN (undoped) the birefringence change is negligibly small (<10^-6) regardless of the state of oxidation or reduction. (3) In LN:Fe the change is between 1.5×10^-3 and 10^-4. (4) It is possible to prepare a sample in which the change is still kept for long time even after stopping the irradiation, which is `oxidized LN:Fe.'

Complex perovskite ceramics, the system Sr(Ni_1/3Nb_2/3)O₃(SNN)–Ba(Ni_1/3Nb_2/3)O₃(BNN) system, have been studied in view of finding materials for use as dielectric resonators at microwave frequencies. A nearly zero temperature coefficient of resonant frequency is obtained for solid solution ceramics with 0.73SNN–0.27BNN composition which corresponds to the order-disorder phase boundary. The relative densities of those ceramics sintered in O₂ atmosphere are more than 99.5%, while those sintered in air are 97∼98.5%. The dielectric constant and the unloaded Q of the ceramics sintered in O₂ atmosphere are 34 and 10,000 at 10 GHz respectively.

Dielectric properties of Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃–Pb(Ni_1/2W_1/2)O₃ pseudo-ternary ceramics were studied. The ceramics could be sintered at 1050°C, exhibited high dielectric constant (15000∼20000) and high resistivity (10¹³Ω·cm, 27000 Ω·F). A small addition of MnO₂ to these ceramics decreased the dissipation factor and caused a peculiar temperature dependence of dielectric constnt. The characteristics of multilayer chip capacitors made of these ceramics with Ag–Pd electrode are described.

Dielectric ceramics with the compositions of Pb(Mg_1/3Nb_2/3) O₃–Pb(Zn_1/3Nb_2/3)O₃–Pb(Fe_2/3W_1/3)O₃ pseudo-ternary system were studied. The ceramics were sintered at 900°C, had high dielectric constant (6500) and small change of dielectric constant with temperature (+3%∼-26% relative to 20°C between -25°C to 85°C). The powder processing of these compositions was studied. Pb₂Nb₂O₇ phase remained in the ceramics with low calcining temperatures. Multilayer chip capacitors with Ag–Pd internal electrodes were fabricated.

Crystal structures, dielectric properties and electrical resistivities for partially substituted lead zinc niobate [Pb(Zn_1/3Nb_2/3)O₃] ceramic were investigated. This ceramic, sintered at 1000–1050°C, was composed mainly of perovskite phase and showed a high dielectric constant (3500–5000) and a high resistivity (approximately 10¹³Ω·cm) when partial substitutions of the Pb site by Ba or Sr and the (Zn_1/3Nb_2/3) site by Ti in the Pb(Zn_1/3Nb_2/3)O₃ were carried out. The reason why the perovskite phase was stable in the sintered body is explained qualitatively by introducing the concepts of an electronegativity difference and a tolerance factor.

Needle-shaped (Pb_1-xBa_x)_1-yLa_2y/3Nb₂O₆ powders are prepared in the presence of molten slat, and one directional grain-oriented ceramics are made from these powders by two-stage hot-pressing technique. The morphology of powder and the dielectric and piezoelectric properties of ceramics are also examined. The obtained grain-oriented ceramics have a large anisotropy in both permittivity and coupling factor depending on the first and second hot-pressing directions. The substitution of Ba or La has remarkable effect not only on morphology of the powder but on electrical properties of the ceramics.

Effect of Pb content on lattice parameters and piezoelectric properties was investigated in Pb(Ni, Zn, Nb)O₃–PbTiO₃–PbZrO₃ solid solution system. High d₃₃-constants, as maximum value of 640×10^-12 C/N, were obtained as a result of exact Pb content control. A bimorph vibrator and multilayer vibrator composed of these materials were confirmed having high performance.

Pressure-less fabrication process of lanthanum-modified lead zirconate titanate (PLZT) electrooptic ceramics has been developed. Fine-particle PLZT powders having excellent reaction and homogeneous composition were fabricated by a chemical preparation method using inexpensive starting materials. Optically transparent PLZT ceramics were obtained by sintering this chemically-prepared powder under O₂-gas flow and atmosphere PLZT powder.

The temperature dependence of internal stress in PTC ceramics with various Curie points was successfully measured by a microindentation and a X-ray diffraction techniques. At ferroelectric phase region, the internal stress decreased with approaching to Curie temperature and reached to almost zero at paraelectric phase region. The effects of internal stress on PTC behavior were discussed with potential barrier related to an effective permittivity.

D.C bias and frequency dependence of the dielectric constant of PLLZT10/53/47 (trigonal-tetragonal phase), 10/65/35 (trigonal-phase) and 10/40/60 (tetragonal phase) compositions have been investigated. The dielectric measurements were carried out 19°C and 100°C temperature in ferroelectric phase and several frequencies between 1 kHz and 1 MHz. Ferroelectric 180° switching and 90° rotating domain model explain the dependence of dielectric constant on electric bias and frequency.

Complex compounds of bismuth Layer-structured ferroelectrics were studied on dielectric and piezoelectric properties. The Curie temperature T_c of solid solution systems based on PbBi₂Nb₂O₉ linearly increases as the tolerance factor t for perovskite-like units of the layer structure rapidly decreases according to the increase of the substitution ion for Pb. A substitution of (NaBi)_1/2, for Pb in the solid solution Pb_1-x(NaBi)_x/2Bi₂Nb₂O₉ (PNBN-100x) system gives the elevated T_c and the easy poling process. Na_0.5Bi_2.5Nb₂O₉ is a very high Curie temperature of 785°C. The coupling factor k₃₃ of the hot-forged PNBN-50 is about 20%.

After the pressed materials were fired to produced a coarsegrained semiconductive ceramic and a diffusion treatment was made to get a boundary layer structure, the electrical properties were measured.

This paper reports an investigation into the fundamental temperature stability of piezoelectric ceramics through thermal aging and thermal shock tests. The dependence of piezoelectricity on thermal aging and thermal shock of low Qm and high Qm materials was clarified. The surface charges generated by the thermal shock caused depolarization of the ceramic elements. In particular, it was found that space charges promoted depolarization in the high Qm materials. A resistor inserted in parallel with the element for the thermal shock test improved piezoelectricity by causing quick relaxation of the induced charges.

A lessening of loss tan δ and three types of dispersion by lowering the low frequency ε, for as-sintered, aged PLZT 8/65/35 are observed. These aging phenomena can be explained by the unpolar phase stabilization whthin a polar region <T_c. Remarkable stabilization begins at ∼60°C. This concept was confirmed by the observation of polar microdomains. Average dimmensions of microdomain were ∼300 Å for polished-annealed samples and ∼100 Å for as-sintered ones.

Hot-pressed ceramics of the solid solution in the ternary systems xBa(La_1/2Nb_1/2)O₃–(1-x)[Pb(Zr_yTi_1-y)O₃] show excellent optical and electrooptical characteristics, comparable to PLZT. Linear and quadratic electrooptical coefficients, r_c and R, are determined for more than ten specimens of various compositions near the morphotropic phase boundary between the tetragonal and the rhombohedral phases and maximum values of r_c=10.73×10^-10m/V and R=12.0×10^-16 m²/V² are observed. Dielectric and electromechanical measurements along with X-ray analysis are also carried out to determine the phase diagram.

Some components of the electrooptic Kerr constants in rutile (TiO₂) and PbMoO₄ crystals have been determined by the interference method. In the measurement of rutile, analyses were made of the temporal response of interference light intensity and the Kerr effect was separated from the themal effect due to electric dissipation. Results were discussed from a viewpoint of the Kerr effect per oxygen-octahedron in comparison with those of various oxide crystals. An additional discussion was made on a Kerr contribution to the light deflection in coplanar-electrode arrangement in comparison with a thermal effect.

Photostriction explainable by the superposition of the bulk photovoltaic effect and piezoelectricity has been investigated in the solid solution ceramics of (Pb, La)(Zr, Ti)O₃. Using the optimum composition PLZT(3/52/48), we have fabricated a photodriven relay as a trial photostrictive actuator. Though the response is rather slow, we have observed primitive relay function controllable by the optical irradiation.

Evaporated films of Mo_cW_1-cO₃ including MoO₃ and WO₃ have been prepared, and the electrochromic absorption spectra have been analyzed on the basis of the small polaron absorption model. Thermomodulation spectroscopy measurements are performed in order to make the analysis precisely. The polaron and phonon energies are determined in the case of the MoO₃ and WO₃ films. In the mixed films, low energy region of the spectra is represented well by either spectrum of WO₃ or MoO₃ film. Peak photon energy of the absorption band in the mixed film depends on both the Mo fraction and the amount of injected charges.

A dielectric loss angle of piezoelectric materials measured at sufficiently low frequencies contains an excess angle resulting from an elastic loss brought by the quasi-static strains. This paper presents an experimental verification of this effect in transducers made of high-coupling piezoelectric ceramics with a low mechanical Q-factor, where the excess loss-angle becomes fairly large. Taking account of both dielectric and elastic losses, an advanced equivalent circuit is also derived, which is useful for estimating the excess loss-angle through the free immitance measurements. In this circuit, the excess loss-angle can be evaluated by a resistance equal to k²/ωC_dQ_B) added in series to the clamped impedance.

Acoustic microscopy has been developed for ferroelectric materials. The observations of a SAW filter, domain wall and grains have been successfully done. To analyze the contrast caused by the defocusing effect, the V_(z) curves have been measured at some appropriate points on the objects. The investigation of anisotropy has been made by utilizing the line focus lens and the propagation characteristics of SAW velocity of a BNN crystal have been determined. The acoustic micrographs of various materials have been shown.

A piezoelectric element possessing a function of three-dimensional actuation for scanning tunneling microscopy is proposed. The characteristics at low frequency are accurately measured by using Talystep. The piezoelectric element responds to small voltage signals with a high resolution of the order of 0.1 nm. The z-axis displacement accompanied by x- and y-axis actuations can be completely compensated by feedback of actuation signals. In order to confirm the actuation properties, specimen scanning in scanning electron microscope is successfully attemped by using the three-dimensional piezoelectric element in place of electron beam scanning by deflection coils.

This paper is concerned with a light-shutter array of PLZT transparent ceramics utilizing newly-developed electrode structure. Relationships between shutter characteristics and electrostrictive effect of the PLZT are investigated. The electrode structure plays significant roles on the reliability of the shutter characteristics. Thus, by introducing a double layer electrode structure coated with resin, the highly stable light-shutter array is obtained to a long time drive. Furthermore, small temperature dependent shutter array can be also realized by controlling each width of the electrode and light-shutter aperture.

A method for optical modulation is described by using a leaky surface acoustic wave device. The Rayleigh wave excited by an interdigital transducer is converted to a londitudinal mode at a liquid-solid boundary after propagating on the substrate material. The ultrasound radiated into water operates as a diffraction grating. Experimental results as an optical modulator using the ultrasonic grating are given with its basic properties for a combination of a He–Ne 0.63 µm laser and water as an acousto-optic material, under the diffraction condition of Raman-Nath type. The amplitude modulation of the optical beam is also demonstrated.

The optical deflection phenomena are observed for some ferroelectric-ferroelastic and ferroelastic crystals. Above a critical angle of incidence, five deflected light beams are observed with a He–Ne laser incidence. The deflected beams are linearly polarized and can be turned off/on by external electric fields. The intensity ratio of the deflected beams to the incident one is of the order of 2×10^-1 for RbHSeO₄ and KH₃(SeO₃)₂ and 10^-3 for Rochelle salt. It was found that the phenomena are due to refraction and reflection of light on the ferroelastic domain walls. The relation between the angle of incidence and the angle of deflection calculated by the Huygens construction quantitatively agrees with the experimental results. Application to optical devices can be proposed utilizing the properties of the deflected beams.

Optical deflectors utilizing the electro-optic effect have simple construction, while the deflection angle is small. Aiming at larger deflection angle, we propose a prism-type optical deflector using PLZT 9/65/35 ceramics as an elector-optic material. Processing the PLZT ceramics into a prism with twin electrodes sputtered on its top and bottom surfaces, we fabricate a prism-type optical deflector, which has the deflection angle up to 1.2 degree at the electric field 900 V/mm.

Printing technique was applied to preparing pyroelectric elements of infrared detectors. Completely sintered ceramic films were obtainable using only pastes that were made from raw powders as fine as 1.0 µm. The films indicated ferroelectricity. The measured pyroelectric coefficient, resistivity and relative permitivity were nearly same as those obtainable on the bulk ceramics formed by conventional sintering technique.

This paper is concerned with the pyroelectric infrared sensor using modified lead titanate ceramics (Pb, Ca)[(Co_1/2 W_1/2), Ti]O₃. The pyroelectric properties of these ceramics have been studied by changing the Ca concentration. With an increase in Ca concentration, the pyroelectric coefficient P and figure of merit Fv increased and reached 4.43×10^-8C cm^-1°C^-1, and 0.61×10^-10C cmJ^-1, respectively. Pyroelectric characteristics have been improved to twice the values for the PbTiO₃ ceramics. Several applications of the sensor are described.

A pyroelectric infrared sensor with a solid state chopper was developed. Ordinarily, the incident rays of pyroelectric IR sensors must be periodically interrupted by means of a chopper, which consists of a motor and a revolving plate, in order to generate a continuous output voltage for temperature measurement. We have developed a new pyroelectric infrared sensor structure by replacing the chopper with a solid state setup consisting of a bimorph vibrator and a grate-type slit plate.

An automatic optical fiber polarization control system has been developed. The system consists of two identical polarization control devices using tiny multilayer piezoelectric actuators, which compress the single mode fiber from both sides. The polarization control devices have low insertion loss of less than 0.1 dB, high extinction ratio of about 18 dB and low half-wave voltage of about 30 V.

This paper describes a quite new type piezoelectric relay of low power consumption and ultra slim shape, using a high efficiency multilayer piezoelectric actuator.

It has been found that a multilayer piezoelectric actuator can produce impact power. The impact energy was measured by experiments using a steel ball under varying experimental conditions. For example, the multilayer piezoelectric actuator of a rectangular prism with a 2×3 mm section and 18 mm height can impel a 4 mm diameter steel ball, whose mass is 0.25×10^-3 kg, to a 0.27 m height. This energy is equivalent to 0.66 mJ. This impact energy is applicable to a dot matrix printing hammer. A trial model of a dot matrix printing hammer using this impact energy, as a method of flying an armature to a platen, has been manufactured in a simple mechanism.

A UHF SAW filter for satellite broadcast receivers has been developed. Features are high center frequency to suppress the image interference, sufficiently flat group delay for linear FM detection and unnecessary any adjustments for tuning. The influence of electrode resistance on the insertion loss, and the triple transit echo caused by wave reflection is investigated in extended Smith's equivalent circuit model, and is effectively applied as an independent design parameter of the radiation and the load conductance. In cosequence the interdigital transducers with the wide aperture stretched nonoverlapped electrodes are efficiently verified to suppress undesired surface wave diffraction and reflection effects without any increase in the insertion loss, and to be able to omit the conventional tuning coils and the intentional impedance mismatching.

This paper deals with experimental results of the 320 kHz timing tank mechanical filter. The composite longitudinal 2-nd mode transducer was made into a sandwich structure by affixing a constant modulus alloy plate to each electrode surface of a piezoelectric ceramic plate. Resonant frequencies, nodal points and suppression of spurious responses due to the 4-th and 6-th order longitudinal modes of the transducer were analyzed. The conclusion is that the timing tank filter dealt with herein, consisting of two transducers, fully satisfied the requirement, including requirement for volume.

A fan consisting of a piezoelectric bimorph tipped with an additional flexible blade is introduced. Since the flexible blade resonates in a large amplitude but the bimorph vibrates in a very small amplitude, the fan can supply sufficient and constant air flow without any structural destruction for a long time. The fan case has two air outlets which are directed oppositely each other. The fan with such outlets can supply an air flow of 4 m³/hr at an applied voltage of 140 V_p–p. Another type of a piezoelectric fan using multi-layered PZT ceramic elements produced by a thick film printing technique is introduced. This fan is suitable for low voltage operation and it can supply an air flow of 1 m³/hr at an applied voltage of 17V_p–p.

A structure for a multilayer piezoelectric ceramic actuator has been studied using finite element method analysis for reducing stresses which are induced at an adhesive layer between the ceramic actuator and a certain body to which the actuator is attached. The stresses are induced by a piezoelectric unstiffened effect (or piezoelectric transverse effect) and they cause mechanical rupture of the adhesive layer. They are successfully reduced for the actuator with both piezoelectric inactive layers and layers which induce a small strain on its top and bottom. It was experimentally confirmed that no mechanical rupture occurs, when adopting an actuator with the improved structure.

Temperature characteristics for multilayer piezoelectric ceramic actuator have been investigated. Thermal expansion coefficient with DC 150 V application is negative, -6×10^-6/°C, at 20°C. Between 0°C and 100°C, an available net displacement under DC 150 V is less changed, within 5%. Temperature rise and dissipation power due to dielectric loss were observed while driving at 0.3∼1.5 kHz. They are about 70°C and 0.7 J/sec at 1.5 kHz, with 150V peak voltage, respectively. The results suggest that a main origin for a temperature rise is dielectric loss.