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Material research and development on piezoelectric ceramics, especially lead-free ceramics, was proposed from a viewpoint of relationships between electromechanical couplig factor and elastic constants such as Young's modulus, Poisson's ratio, modulus of rigidity and bulk modulus. We developed a method to be convenient to measure acoustic wave velocities by an ultrasonic thickness gauge with high-frequency. From the values and changes in longitudinal and transverse wave velocities before and after DC poling, it was clarified that the relationships between coupling factor and elastic constants, and furthermore, the ceramic bulk density was important to improve the coupling factor in lead-free ceramics. In the case, the ratio of transverse wave velocity to longitudinal wave velocity was utilized to estimate compositions with higher coupling factor. As a result, the candidates of lead-free ceramic compositions with higher coupling factor were proposed. The measurement of sound velocities was an effective too...

Research and development of controlling and evaluation on ferroelectric domain structures are described in piezoelectric ceramics composed of lead zirconate titanate, lead titanate, barium titanate, alkali bismuth niobate and alkali bismuth titanate. Ferroelectric domain switching and domain rotation could be explained by DC poling field dependence of dielectric and piezoelectric properties. In addition, Young's modulus and Poisson ratio toward poling field in piezoelectric ceramics were investigated by measuring longitudinal and transverse acoustic wave velocities to clarify the relationships between high piezoelectricity and the values. Increasing domain alignment by applying poling field, basically, the Young's modulus decreased and Poisson ratio increased.

The progress of ferrite recrystallisation in low carbon steel was slower than in ultralow carbon steel. The hardness of the non-recrystallised ferrite grains gradually decreased with increasing annealing time in ultralow carbon steel, but gradually increased with increasing annealing time in low carbon steel. The amount of Ti containing precipitates increased slightly during annealing in ultralow carbon steel, but increased remarkably with increasing annealing time in low carbon steel. These results suggest that the softening of non-recrystallised ferrite grains during annealing in ultralow carbon steel may reflect the progress of recovery and the Ostwald ripening of Ti containing precipitates formed during annealing. In contrast, the hardening of non-recrystallised ferrite grains in low carbon steel may be due to the precipitation hardening of TiC formed during annealing.

Giant k 31 in (1-x)Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 (x=0.251∼0.301)(PMNT)(110) single-crystal plates with dimensions of 13 L x4.0 W x0.25 T mm was investigated by the chemical composition dependence of ferroelectric properties,impedance response on the k 31 mode, P-E hysteresis loop and electric-field induced strain. The dielectric and piezoelectric measurements versus the Ti content (x) showed four groups. Giant k 31 of more than 80% was obtained for x=0.251∼0.293, and the maximum k 31 reached 92%(x=0.291). A mechanism for realizing giant k 31 was explained by the relationships between the crystal planes, which strongly affect the direction of the spontaneous polarization and poling direction.

Domain size in Pb[(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 ]O 3 (PZNT91/09) single-crystal plates was analyzed by measuring the impedance responses of k 31 fundamental vibration and their overtones. Increasing the poling field (E), the split impedance responses of odd number overtones became single response, as a result, the PZNT91/09 single-crystal plate possessed giant k 31 over 80%. The homogeneity of the domain size distribution was estimated by the E to realize the single response of the overtones. For instance, the frequency of 410 kHz to obtain the 11th overtone on k 31 mode corresponded to 1.1 mm on domain size distribution.

The processes to realize giant k 31 over 80% were investigated. The giant k 31 in Pb[(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 ]O 3 (PZNT91/09) single-crystal plates was obtained by controlling the process combination of the DC poling and the thermal treatment. Frequency responses of impedance up to 500 kHz in various plate samples were analyzed on the length extensional vibration modes of k 31 and k 32 . It was found that there were two frequency constants of 520 kHz-m and 830 kHz-m on these modes. The anisotropy on k 31 and k 32 modes can be explained by the reorientation for their frequency constants. Furthermore, the appearance of the giant k 31 needed the low frequency constant in k 32 mode, and finally, the PZNT91/09 single crystals changed into a new phase with the low frequency constant in k 31 mode.

Pb[(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 ]O 3 single crystals with various crystal planes were evaluated regarding electromechanical coupling factor of k 31 mode and piezoelectric d 31 constant. Although these values depended on their crystal planes, the giant k 31 and d 31 were obtained in the case of the (100) crystal plane poled along [001] of the original cubic direction. The dielectric constant at room temperature increased with the time in the crystal of (110) plane, while the dielectric constants of the crystals with (100) and (111) planes were unchanged. The crystal plane dependence of ferroelectric properties and their aging characteristics could be explained by the relationships between the directions of the polarization axes and poling field. The bipolar pulse field dependence of k 31 and d 31 were also investigated in comparison with the DC poling field dependence. The giant k 31 and d 31 were obtained in the crystal of (100) plane by the bipolar pulse poling as well as by the DC poling.

Piezoelectric unimorphs and bimorphs were fabricated by utilizing (100) plane Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3(PZNT91/09) single-crystal plates with giant k31 over 80%, which appeared in the case of a phase with low crystal symmetry. The electromechanical coupling factors on bending mode (k b ) were 64.7% (PZNT91/09 single crystals) and 20.6% (PZT ceramics) in the case of unimorphs. The values of k b in bimorphs were 69.8% (PZNT91/09 single crystals) and 31.2% (PZT ceramics), respectively. Furthermore, the PZNT91/09 single-crystal bimorph showed the superior piezoelectric properties such as three times larger impedance ratio on the resonant and the anti-resonant frequencies. The single-crystal devices possessed the excellent displacement characteristics in comparison with the ones of the PZT ceramic devices.

We found the giant electromechanical coupling factor of k31 mode to be over 80% and the piezoelectric d31 constant to be nearly −1700 pC/N in ferroelectric single crystals of Pb[(Zn1/3Nb2/3)0.91 Ti0.09]O3 (PZNT91/09). The origin of the giant k31 was as follows: the crystal with multi-domains changed into one having a mono-domain in the direction perpendicular to the poling field (k31 mode) as well as in the direction parallel to the poling field. The discovery of the giant k31 found a key to clarify the origin of the high piezoelectricity in PZNT91/09. Investigating the crystal orientation dependence of k31 and their aging characteristics, the giant k31 and d31 accompanied with the superior aging characteristics could be obtained in the case of the rhombohedral (100) crystal poled along [001] of the original cubic direction. Furthermore, it is found that the Young's modulus Y (0.89×1010 N/m2) in rhombohedral PZNT91/09 with giant k31 is remarkably small. Therefore, we believe that the high piezoelectricity...

Temperature and poling field dependences of the properties of large high-quality piezoelectric single crystals of Pb[(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 ]O 3 (PZNT91/09) grown by the Bridgman method were measured. The single crystals poled along [001] of the original cubic direction possess giant electromechanical coupling factor k 31 over 80% and piezoelectric d 31 constant nearly m 1700 pC/N. These giant k 31 and d 31 constants results from the control of ferroelectric domain configuration. PZNT91/09 multi-domain single crystal became single-domain in the directions parallel and perpendicular to the poling field resulting in the appearance of giant k 31 and d 31 .

Domain structures of ferroelectric materials were investigated by measuring the poling field dependence of dielectric and piezoelectric properties. Ferroelectric materials evaluated consist of as follows: soft and hard lead zirconate titanate (PZT) ceramics with tetragonal and rhombohedral phases, lead titanate (PT) ceramics, barium titanate (BT) ceramics and a relaxor based single crystal of Pb(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 O 3 (PZNT). Changing the poling field (E) from 0 M +E M 0 M m E M 0 to +E, the electromechanical coupling factor (k p , k 33 ), dielectric constant ( l r ) and frequency constant (fc) were measured. The minimum k p , k 33 and l r were obtained at the same E because of the 180° domain clamping. Furthermore, the E due to the domain clamping corresponded to the coercive field (Ec) determined by the poling field dependences. At the Ec, maximum fc was confirmed in the cases of soft PZT (tetragonal and rhombohedral) and hard PZT (tetragonal) ceramics, BT ceramics and PZNT single crystal. It ...

Domain switching and rotation in soft lead zirconate titanate (PZT) ceramics were investigated in comparison with those in hard PZT ceramics by measuring the poling field dependence of the dielectric and piezoelectric properties. The minimum dielectric constant (fcp) and maximum frequency constant (fcp) were observed at the coercive fields, which correspond to the poling fields required to obtain the minimum planar coupling factor. These phenomena were due to the 180° domain clamping at these fields. The fields of 90° (71° or 109°) domain rotation were estimated using the relationships between the maximum fcp and minimum fcp. While minimum ϵt and maximum fcp due to domain clamping were observed in the compositions of tetragonal and rhombohedral soft PZT ceramics, domain rotations which caused maximum ϵt and minimum fcp were mainly observed in rhombohedral hard PZT ceramics. It was thought that the reason why domain rotations which caused maximum ϵt and minimum fcp were not obtained in soft PZT wa...

Two steel plates were bonded with oil-accommodating adhesives, the components of which are epoxy resin, NBR (nitrile rubber) modified epoxy resin, CaCO3 and silica powder. The effect of components on the apparent shear strength was studied using the plates, which were covered with rust-preventing oil. The shear strength increased most effectively with the silica powder content, as compared with other components. Further, each component was exposed to the vapour of rust-preventing oil. Silica powder absorbed the largest amount of oil among the components per unit weight. We concluded that the performance of the oil-accommodating adhesive was attained by the strong oil absorption ability of silica powder in the adopted adhesive.

Lead zirconate titanate ceramics were evaluated to examine the relationship between domain structures and ferroelectric properties. Responses to repeated voltage pulses applied to the ceramics were measured by a high voltage test system as a dynamical evaluation. Through the evaluation, it was clarified the domain behavior for the 90° (71° and 109°) domain rotation, 180° domain switching and clamping, and transient phenomena on the domain orientation.

We investigated the ceramic bulk density, crystalline phase, microstructure and electrical property in Pb(Co1/3Nb2/3)O3—PZT ceramics fired in air and oxygen atmosphere to clarify the origin of their semiconductive characteristics. Although a pyrochlore phase due to B-site vacancies produced by Co vaporization while both firings was segregated and suppressed the grain growth, the ceramics showed high resistivity (ρ) and small dielectric loss (tan δ). An addition of CoO (∼0.1 wt%) to the ceramic composition with stoichiometry inhibited the Co vaporization and the production of the pyrochlore phase in the perovskite phase. As a result, the ceramic bulk density of the compositions added a small amount of CoO increased. However, the grain growth was promoted and the ceramics became low ρ and large tan δ in case of the compositions added a large amount of CoO (0.4—6.0 wt%). Although PbO was segregated in addition to a perovskite phase on the ceramics fired in air, the perovskite single phase was obtain...

Semiconducting Pb(Co1/3Nb2/3)O3-PbTiO3-PbZrO3 ceramics were investigated to improve poling characteristics. Poling conditions, such as poling temperature and poling field, were chosen to obtain high piezoelectricity. The ceramics with improved poling characteristics were produced by increasing firing temperature. Moreover, the ceramics had relatively large electromechanical quality factors as well as high coupling coefficients in comparison with the ceramics composed of Pb(Ni1/3Nb1/3)O3-PbTiO3-PbZrO3.

We have studied the fracture mechanism and oil absorption in an oil-accommodating adhesive. Shear and T-peel tests were carried out for test pieces prepared from two steel plates bonded with the adhesive, which is mainly composed of epoxy resin, modified NBR, and inorganic powders. When the modified NBR content was varied from 3 to 25 wt%, both the shear and the T-peel strengths increased with the modified NBR content and levelled off at around 10 wt% modified NBR content. This behavior was coincident with that in the tear test by the samples prepared from cured adhesive. Therefore, fracture in the shear and T-peel tests is attributed to the tearing of cured adhesive. The oil absorbed in the non-cured adhesive bleeds out during curing. However, this oil can be stored in the grooves of steel plates.

The Ni alloy electrode was used for a bottom electrode of PZT thin films prepared by sol-gel process. Although PZT films were crystallized on soda–lime glass substrates with the alloy electrodes at a relatively low temperature of 500°C, second phases of Pb3O4 and ZrTiO4 were produced on the electrode in addition to the perovskite PZT phase. In order to prevent the second phases forming, the heat treatment time of the electrode was increased to obtain the thicker Al2O3 layer on the alloy electrode. The second phases decreased with increasing the heat treatment time; however, the phases did not disappear. When BaTiO3 films were inserted between the electrodes and PZT films, the PZT single phase was obtained. The tan δ of the films decreased with decreasing the amount of the second phases, finally it became 3.9%, the film of which possessed a remanent polarization of 20 μC/cm2.

We studied ferroelectric domain by measuring various hysteresis loops of relative dielectric constant (ϵr), and frequency constant (fcp) versus electric field strength (E) on PZT ceramics. The E's to get the peaks of Δϵr were equivalent to the E's caused minimum fcp. It was thought that these E's of 2–4 kV/cm and 15 kV/cm corresponded to threshold electric fields (Et) of 71° and 109° domain rotations. PZT ceramics were prepared to control ferroelectric domain structures by a reactive calcination. This ceramic powder processing was that a mixture of TiO2 powder and ZrO2 powder was precalcined below a temperature of 1000°C. The ceramics had the same bulk density as ceramics prepared by a conventional powder processing but large Vickers' hardness. It was thought that the differences in Vicker's hardness and relative dielectric constant between both the powder processings were due to a change in ferroelectric domain structure of each PZT ceramic.

In recent years bonding between two steel plates was accomplished with an oil-accommodating adhesive without requiring degreasing of the steel. In this paper, the exclusion process of the oil was investigated in this adhesive on the assumption that the oil was absorbed into the adhesive layer. It was found that the oil layer essentially disappeared in the initial step of curing in which the temperature was raised to 180°C, because the diffusion rate of the oil into the adhesive increased abruptly with temperature. Therefore, the bonding process in this case is not influenced by the presence of oil on the steel plates.

The relationships between microscopic properties such as interfacial shear strength (IFSS) and macroscopic properties such as flexural strength were investigated for CFRP prepared from carbon fiber and epoxy resin. Flexural, tensile and impact strengths all went through maximum values when plotted against the surface treatment time of the carbon fiber. The flexural strength of CFRP as a function of the treatment time of the carbon fiber behaved similarly to the adhesive strength of the resin and carbon fiber. Also, the results indicated that the bahavior of tensile and impact strengths varied with the treatment time in much the same way as the interfacial shear strength did. The occurrence of these two types of macroscopic and microscopic property effects can be understood by taking into account the chemical activity and roughness of the carbon fiber surface.

Perovskite PZT phase was produced on Ni alloy/SiO2-Si substrate at a substrate temperature above 500° C by laser ablation, but pyrochlore phase or Pb(Zr, Ti)3O7 phase was produced on Pt/SiO2-Si. The 0.15μm-thick film showed a remanent polarization of 15 μC/cm2 at an applied voltage of 5V; moreover, the switched charge(Qsw) and the switching time were 5.0μ/cm2 and 4.5 μs respectively for a film with 0.7 μm thickness and an electrode area of 0.002cm2. The fatigue in Qsw occurred around 108 cycles.

This paper describes an improved method for the accurate determination of the contact angle of a liquid droplet on a monofilament. Theoretically, in this improved method, contact angles do not depend on droplet size or the radius of the fiber. The accuracy of this method is thus expected to be higher than any other standard methods.

Adhesion of polypropylene sheet with steel plate was investigated using a mixed adhesive which was composed of a sitane coupling agent with peroxide. This adhesive was applied to both surfaces of polypropylene sheet by brushing or spraying. A steel/polypropylene/steel laminated structure was formed at around 200°C. The effects of the bonding conditions on peel strength were investigated in the laminates. Considerable reduction of the amount of the adhesive used was achieved by adopting a spraying technique, and excellent peel strength was attained.

The method of universal calibration was applied for polyoxymethylene in gel permeation chromatography. Successful molecular weight distribution curves were obtained for polyoxymethylene from chromatograms. Further, the weight average molecular weights from gel permeation chromatography were in good agreement with those from light scattering.

In reply:—We appreciate Dr. Kramer-Johansen's interest in our paper and suggestions for future study.As with the nature of observational studies, it is true that the information on why this particu...

A gel permeation chromatograph equipped with dual detectors provides very useful information on compositional and molecular weight distributions. One copolymer composed of nylon 12 and polytetramethylene ether glycol, and the other of nylon 6 and natural rubber were discussed in this study. By trifluoroacetylation of the amide group, these polymers became soluble in common solvents such as dichlcromethane and tetrachloroethane. Good chromatograms were obtained using these solvents for the above copolymers. At the same time, the compositional heterogeneity was determined from the chromatograms obtained with refractive index and ultraviolet detectors.

Saturated hydrocarbons are generally eluted according to molecular volumes in gel permeation chromatography (GPC). Other compounds, containing polar groups such as hydroxyl and carbonyl groups, deviate from the molecular volume/elution count relationship which is prepared using saturated hydrocarbons. The deviation is more or less observed regardless of the kinds of eluents. In this paper, this problem is investigated in detail with respect to infrared(IR) and proton magnetic resonance(NMR) spectra, and concentration dependences of peak heights and elution volumes in GPC. IR and NMR spectra reveal that alcohols, ketones and esters are strongly solvated by eluent molecules such as chloroform and tetrahydrofuran(THF). The solvation effect leads to faster elution for these compounds than expected for aliphatic hydrocarbons. On the other hand, the concentration dependences of elution counts and peak heights prove the adsorption of amines on polystyrene gel in chloroform. In fact, the elution rates of...

Gel permeation chromatograms were recorded for an acrylonitrile-styrene copolymer in both dimethylforamide (DMF) and DMF-LiBr-H2O as solvents. In the DMF solvent, a bimodal chromatogram was observed, while in the DMF-LiBr-H2O solvent, monomodal behavior was observed for the same sample. In order to investigate the cause for such behavior, the molecular weight averages of the copolymer were determined in these solvents. Further, the chromatogram in the former solvent was corrected for observed nonlinearity of the calibration curve. We concluded that apparent differences in the chromatograms are due, at best in part, to the nonlinearity. General conditions for the appearance of bimodal chromatograms were examined based on this idea, using simulation techniques.

Propylene was polymerized with the catalyst system (C2H5)2A1C1/ VCk/ anisole at -78°C using various conditions. The resulting polymers were successively extracted by diethyl ether, hexane, and heptane, leaving the residue. The polymers of the four series were characterized by intrinsic viscosity, gel permeation chromatography, 13C nuclear magnetic resonance, infrared spectroscopy, x-ray diffraction, and by differential scanning calorimetry. The combined evidence from the various methods indicates that this catalyst system leads to stereoblock polymers which can be fractionated according to stereochemical composition and sequence length.

Elution behavior of organic compounds in gel permeation chromatography was investigated using chloroform as eluent. In aliphatic hydrocarbons, the elution counts decreased linearly with increasing the molecular volumes. In aromatic hydrocarbons, the relation between molecular volume and elution count slightly shifted toward lower counts. The elution counts in esters, ketones, amides, alcohols and carboxylic acids always fell in lower elution counts than expected by aliphatic hydrocarbons. This fact suggests that all these compounds are solvated by eluent molecules. Amines and chlorides exhibit an adsorption effect on cross-linked polystyrene gel. These compounds are eluted behind the corresponding hydrocarbons for given molecular volumes, which were obtained by dividing molecular weight by density.