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Showing papers on "Piezoelectricity published in 1980"


Book
01 Jan 1980

555 citations


Journal ArticleDOI
TL;DR: This is the 100th anniversary of the discovery of the piezoelectric effect by the brothers Curie as mentioned in this paper, which produced one of the principal electromechanical transducer effects.
Abstract: This is the 100th anniversary of the discovery of the piezoelectric effect by the brothers Curie. While this was a scientific curiosity for the next third of a century, with the work of Langevin it produced one of the principal electromechanical transducer effects. Quartz, first used as a transducer, also received wide use in controlling oscillators and in selective wave filters. Quartz was soon replaced by Rochelle salt for transducers. This is a rather unstable crystal, which, however, was the first ferroelectric having an intrinsic polarization between its two Curie temperatures. A theory of this effect was given by the writer. Most crystal transducers have been replaced by ferroelectric ceramics. A material somewhat similar to a ferroelectric is an electret. These have become very useful in transmitters and receivers. Finally, thin films of piezoelectric crystals are useful for producing high frequencies in such devices as the acoustic microscope.

244 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured dielectric and piezoelectric responses caused by a high electric field and a 10Hz small strain using a minicomputer system.
Abstract: Dielectric and piezoelectric responses caused by a high electric field and a 10‐Hz small strain have been simultaneously measured for stretched polyvinylidene fluoride using a minicomputer system. The electric field was applied up to 240 MV/m in a sinusoidal or triangular wave form in the frequency range 10−4–10−2 Hz at temperatures between −100 and 100 °C. Ferroelectric hysteresis loops were observed even below the glass‐transition temperature of −60 °C. At 20 °C the 120‐MV/m electric field gave the remanent polarization Pr of 50 mC/m2 which resulted in the piezoelectric activities e31 and e32 of 70 and 7.5 mC/m2, respectively. The origin of Pr was confirmed to be the molecular dipole orientation because the value of Pr was independent of the frequency of applied field. The coercive field Ec significantly decreased with increasing temperature from 180 MV/m (−100 °C) to 25 MV/m (100 °C), while Pr showed only a slight temperature dependence.

239 citations


Journal ArticleDOI
TL;DR: In this paper, a simplified fabrication technique has been developed by mixing volatilizable plastic spheres and PZT powder, and when sintered and backfilled with epoxy, and poled, these composites give excellent piezoelectric voltage coefficients.

233 citations



Journal ArticleDOI
TL;DR: In this paper, a model describing losses in ferroelectric ceramics by the damped motion of 90° domain walls has been developed and the dependence of the complex dielectric, elastic and piezoelectric constants on th...
Abstract: A model, describing losses in ferroelectric ceramics by the damped motion of 90° domain walls has been developed. The dependence of the complex dielectric, elastic and piezoelectric constants on th...

122 citations


Journal ArticleDOI
TL;DR: In this paper, the piezoelectric properties of an alternative copolymer of vinylidene cyanide and vinyl acetate were investigated in connection with the results of dynamic modulus, X-ray diffraction, and electrostriction effect.
Abstract: The piezoelectric properties of an alternative copolymer of vinylidene cyanide and vinyl acetate were investigated in connection with the results of dynamic modulus, X-ray diffraction, and electrostriction effect. The rolled and polarized copolymer showed piezoelectricity strong enough to be comparable to that in poly(vinylidene fluoride) films treated by the same poling conditions, but the piezoelectric activity prevailed at high temperature exceeding 100°C. This strong piezoelectricity is considered due to the introduction of large dipole moments such as C–CN groups in the molecule and to the orientation of this large dipole moment in the film.

105 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that by appropriate variation of poling conditions and sample microstructure, relatively large piezoelectric constants can be obtained for nylon 11 films (d31∼3 pC/N).
Abstract: At the present time, only poled, drawn poly (vinylidene fluoride) (PVF2) films give evidence of sufficiently high piezoelectric response to be useful in device applications, and for this reason the great majority of research has centered around this polymer. As in the case of PVF2, many odd nylons crystallize in a polar space group with a large net dipole moment in the unit cell. On the basis of the understanding now reached of the properties of poled PVF2 films, it would appear that the odd nylons have the potential to make films with high piezoelectric activity. Piezoelectricity and pyroelectricity in nylon 11 films have been studied previously. The piezoelectric strain constants found were larger than most polymers, but still two orders of magnitude less than the corresponding activity found in poled oriented PVF2 (d31∼20 pC/N). Studies carried out in this laboratory have shown that by appropriate variation of poling conditions and sample microstructure, relatively large piezoelectric constants can be obtained for nylon 11 films (d31∼3 pC/N). The dependence of the piezoelectric strain constant d31 on poling temperature, poling field, and crystal structure will be discussed.

103 citations


Journal ArticleDOI
TL;DR: The first piezoelectric ceramic was barium titanate and it is still used as discussed by the authors, and the lead titanate zirconate ceramics were introduced about 1955 and quickly became the most widely used material.
Abstract: Piezoelectric ceramics have been used for a little over 30 years. The first piezoelectric ceramic was barium titanate and it is still used. The lead titanate zirconate ceramics were introduced about 1955 and quickly became the most widely used piezoelectric material. Compositions were developed for many specific applications, as the strength of ferroelectricity in lead titanate zirconate allowed major chemical modification. The development and characteristics of these materials are described and applications are reviewed. Major emphasis is placed on consumer applications, as it is these that account for the major business in piezoelectric ceramic materials.

102 citations


Proceedings ArticleDOI
01 Jan 1980

93 citations


Journal ArticleDOI
TL;DR: Theoretical models of the various origins of piezo-and pyroelectricity, which include piezoelectricity due to inhomogeneous material properties and strains, are reviewed in this article.
Abstract: Piezoelectricity and related properties of polymers are reviewed. After presenting a historical overview of the field, the mathematical basis of piezo- and pyroelectricity is summarized. We show how the experimentally measured quantities are related to the changes in polarization and point out the serious inequlity between direct and converse piezoelectric coefficients in polymers. Theoretical models of the various origins of piezo- and pyroelectricity, which include piezoelectricity due to inhomogeneous material properties and strains, are reviewed. Relaxational effects are also considered. Experimental techniques are examined and the results for different materials are presented. Because of the considerable work in recent years polyimylidene fluoride, this polymer receives the majority of the attention. The numerous applications of piezo-and pyroelectric polymers are mentioned. This article concludes with a discussion of the possible role of piezo- and pyroelectricity in biological system.

Patent
27 Mar 1980
TL;DR: In this paper, a piezoelectric flexure device is described in which the piezelectric element(s) comprises a flexible polymeric layer (e.g., a suitably polarized polymeric film) which is tightly wound about an axis to produce a plurality of substantially concentric layers.
Abstract: Disclosed herein is a piezoelectric flexure device in which the piezoelectric element(s) thereof comprises a flexible piezoelectric layer (eg a suitably polarized polymeric film) which is tightly wound about an axis to produce a plurality of substantially concentric layers of piezoelectric material Positioned between adjacent piezoelectric layers are conductive layers which function as electrodes for either applying an electric field across the piezoelectric layers to cause the device to flex, or for detecting the electrical potential produced in the device as a result of subjecting the piezoelectric element to a mechanical stress Owing to the wound nature of the piezoelectric element, the device is relatively simple to manufacture and the conductive layers are less apt to crack or break during the manufacturing process Also disclosed herein are techniques for producing such piezoelectric flexure devices

Journal ArticleDOI
TL;DR: In this paper, the influence of crystal symmetry, macrosymmetry, and inter-phase connectivity have been used to explore possible macrostructures of interest as piezoelectric or pyroelectric composites.
Abstract: Consideration of the influence of crystal symmetry, macrosymmetry, and inter-phase connectivity have been used to explore possible macrostructures of interest as piezoelectric or pyroelectric composites. Based on these design considerations, ceramic-plastic composites have been fabricated with 3–3 phase connectivity by the replication of natural template structures such as coral. Composites prepared in this way have piezoelectric 933 and 9h coefficients more than an order of magnitude higher than the coefficients of the homogeneously poled ferroelectric ceramic. Large voltage coefficients were also obtained from 3–1 piezoelectric composites made by embedding PZT fiber arrays in epoxy cement. Processing methods are described for producing straight and helical piezoelectric fibers by both extrusion and casting of PZT slips. Pyroelectric measurements on ceramic-plastic composites led to two interesting results: thermal expansion mismatch between the two phases can couple to the piezoelectric coeffic...

Journal ArticleDOI
TL;DR: In this article, a plate-type theory is developed for the flexural-extensional vibratory response and static voltage deformation of heterogeneous piezoelectric circular transducers.
Abstract: A plate‐type theory is developed for the flexural‐extensional vibratory response and static voltage deformation of heterogeneous piezoelectric circular transducer elements. Known results for homogeneous disks and bimorphs are shown to be special cases of the theory. Application is made to the design of simply supported metal‐piezoceramic unimorph disks, and thin piezoceramic bimorph benders possessing metallic electrodes of non‐negligible thickness.

Journal ArticleDOI
TL;DR: In this paper, the behavior of a coated piezoelectric crystal detector for the monitoring or traces of atmospheric gases partitioning into the coating on the crystal is predicted, and the effects of variable experimental parameters such as detector cell volume, gas flow rate, analyte concentration, distribution and size of detector coating are discussed.

01 Jan 1980
TL;DR: In this article, the approximate 2D theory derived in Part I is applied here to the time harmonic problems of plane-strain and axisymmetry, where the output voltage is computed as a function of time when the crystal is an element in a known electrical circuit.
Abstract: Abstract The approximate 2-D theory derived in Part I is applied here to the time harmonic problems of plane-strain and axisymmetry. Also, the transient axisymmetric solution is obtained for a circular layer that is suddenly released from a transverse concentrated central load on one face and an opposing ring load along the outer edge of the other face. For this problem the output voltage is computed as a function of time when the crystal is an element in a known electrical circuit.

Journal ArticleDOI
TL;DR: In this article, the authors considered the case of a nonlinear interaction of the electric field with a deformable insulator, and they proposed the linear electroelastic equations for small dynamic fields, superposed on a static bias obtained from the nonlinear system.
Abstract: In piezoelectricity, the stress equations of motion are coupled to the charge equation of electrostatics by means of the linear piezoelectric constitutive equations which contain the piezoelectric constants that couple the small strain to the electric field. In the case of the more general nonlinear interaction of the electric field with a deformable insulator, the Maxwell electrostatic stress tensor must be included in the description. Furthermore, in the nonlinear case, a rotationally invariant combination of the electric field and the deformation occurs in the constitutive equations in place of the electric field for the same reason that the finite train occurs. The linear electroelastic equations for small dynamic fields, superposed on a static bias obtained from the nonlinear system, are more general than the linear piezoelectric equations in that the linear constitutive equations depend on the small local mechanical rotation, as well as the small strain. Nevertheless, when the biasing stress and ele...

Journal ArticleDOI
TL;DR: A Pb(Zr, Ti)O3+0.5 Nb2O5 ceramic composite transducer exhibiting 3-3 connectivity was prepared by conventional powder methods as mentioned in this paper.
Abstract: A Pb(Zr, Ti)O3+0.5 Nb2O5 ceramic composite transducer exhibiting 3–3 connectivity was prepared by conventional powder methods. The dielectric, elastic and piezoelectric properties were measured. It exhibits a large piezoelectric voltage output coefficient (g-constant) of 130×10-3 Vm/N. Utilizing the new material, hydrophone sensitivity was increased to nearly four times that of normal Pb(Zr, Ti)O3 ceramics.

Patent
24 Oct 1980
TL;DR: In this article, a piezoelectric actuator with a snap-action device and an electric field was used to generate an opposing force to the actuator in excess of the reaction force.
Abstract: A piezoelectric actuator including a piezoelectric element; a snap-action device for exerting a positive force in opposition to the piezoelectric element and having a predetermined reaction force that must be overcome to cause the snap action; the piezoelectric element including piezoelectric means for providing an opposing force to the snap-action device in excess of the reaction force; and means for applying an electric field to the piezoelectric means to enable it to generate the opposing force and store energy in the snap-action device to enable occurrence of the snap action.

Journal ArticleDOI
TL;DR: In this paper, a sintered, extruded honeycomb configuration of PZT with various polymers was fabricated for low voltage displacement and pulse echo applications and the resulting composites have thickness mode electromechanical coupling coefficients (kt) which are ∼25% greater than that of homogeneous PZTs, and are readily adaptable for broad bandwidth operation.

Journal ArticleDOI
TL;DR: In this article, a multilayer PZT transformers with internal electrodes for hard PZTs were introduced and the piezoelectric coefficients of the multilayers were shown to be approximately 20% lower than those of similar plain PZt devices.
Abstract: Platinum internal electrodes have been introduced into PZT compositions in a multilayer configuration by a conventional tape casting process. Electrical property data for the devices suggest that the piezoelectric coefficients of the multilayer configuration are approximately 20% lower than those of similar plain PZT devices. However, the applied voltage/displacement ratio is much lower in the multilayer compared to the plain devices. Resonant properties are almost unaffected by the presence of internal electrodes for hard PZT compositions. Piezoelectric transformers with multilayer primaries show improved transformer ratios compared to conventional devices.

Journal ArticleDOI
TL;DR: In this article, the low frequency applied voltage-displacement characteristics of PZT-4 and PZTs5H piezoelectric ceramics, in both disc and tubular form spectra obtained with a separation scanned Fabry-Perot interferometer, were discussed in relation to the results obtained.
Abstract: The low frequency applied voltage-displacement characteristics of PZT-4 and PZT-5H piezoelectric ceramics, in both disc and tubular form spectra obtained with a separation scanned Fabry-Perot interferometer. The operation of such interferometers, when used without servo-control, is discussed in relation to the results obtained. Creep, variation of strain constant with bias voltage and the effects of non-continuous cycling were also investigated.

Journal ArticleDOI
TL;DR: It is shown that the electromechanical behavior of bone in cantilever bending, in which the signal is related to the stress gradient, can be viewed as a consequence of a variation of a piezoelectric modulus along this gradient.

PatentDOI
TL;DR: In this article, an ultrasonic wave transducer is formed from a body of piezoelectric material having non-uniform thickness, and each location on the transducers is resonant at a different frequency according to the thickness at that point.
Abstract: An ultrasonic wave transducer is formed from a body of piezoelectric material having nonuniform thickness. Each location on the transducer is resonant at a different frequency according to the thickness at that point. By changing the frequency of the applied excitation signal, the origin and direction of the radiation can be altered.

Book ChapterDOI
01 Jan 1980
TL;DR: In this paper, it was shown that improved orientation of dipoles and reduction of ionic impurities should increase p y and d p for PVDF by a factor of two above typical values presently reported.
Abstract: Some polymers can be made both piezo- and pyroelectric by suitable application of a large electric field. This effect is true piezo- and pyroelectricity rather than electrostriction, conduction, electromechanical effects, or the motion of conductors in the field of space charges. Two distinct types of polymers can be piezoelectric. Amorphous polymers are piezo- and pyroelectric by virtue of a nonequilibium but kinetically stable net dipole orientation in the amorphous phase of the polymer. The semicrystalline polymers are piezoelectric due to alignment of polar, ferroelectric crystals dispersed in the amorphous phase. In both types of polymers, magnitudes of the piezo- and pyroelectric effects are in accord with the expected temperature and pressure dependence of the dipole model. Polarization changes primarily because of dimensional changes of the sample. Space charges embedded in the polymer normally will not produce large piezoelectric and pyroelectric currents. Those embedded near the crystalliquid interfaces tend to reduce the piezo- and pyroelectricity. Improved orientation of dipoles and reduction of ionic impurities should increase p y and d p for PVDF by a factor of two above typical values presently reported. The sensitivity of amorphous and semicrystalline polymers is limited mainly by dipole moment per unit volume and breakdown strength.

Journal ArticleDOI
TL;DR: It is found that the electrodeposited films were more organized and exhibited higher piezoelectric coefficients than the evaporated films, suggesting that the effect originates either at the level of the tropocollagen molecule or, at most, with aggregated structures no larger than 50 Å in diameter.
Abstract: Tissue collagen exhibits several levels of structural organization, and this complicates efforts to determine the origin of its piezoelectricity. We made collagen films-by evaporation and electrodeposition from solution-and examined the relation between collagen's piezoelectricity and its electron microscopic appearance. We found that the electrodeposited films were more organized and exhibited higher piezoelectric coefficients than the evaporated films. Despite this, the evaporated films were piezoelectric, thereby suggesting that the effect originates either at the level of the tropocollagen molecule or, at most, with aggregated structures no larger than 50 A in diameter.

Patent
21 Apr 1980
TL;DR: In this paper, a process for preparing polyvinylidene fluoride type (PVDF) films having highly stable piezoelectricity and pyroelectricity, by stretching PVDF films, while causing corona discharge, across the electric field formed by discharging, to effect thereby to polarization of film.
Abstract: A process for preparing polyvinylidene fluoride type (PVDF) films having highly stable piezoelectricity and pyroelectricity, by stretching PVDF films, while causing corona discharge, across the electric field formed by discharging, to effect thereby to polarization of film.

Journal ArticleDOI
TL;DR: In this article, a ternary piezoelectric ceramics transformer with a voltage step-up ratio of about 150-200 was presented, and the experimental results made on the material properties and the characteristics of transformer elements are presented.
Abstract: This paper presents a piezoelectric ceramic transformer which has a no-load alternating current voltage step-up ratio of about 150–200. The composition of the material is: ternary piezoelectric ceramics. The experimental results made on the material properties and the characteristics of transformer elements are presented. Based on the analysis of scanning electronic microscope and X-ray diffraction, the relations between physical properties and microstructure of piezoelectric ceramics were studied. With laser holography, under high voltage, the vibration modes of the transformer elements were measured. Amplitude distributions of vibration modes were quantitatively computed. The results were related with the voltage step up ratio. Analysis and comparison were made between vibration modes. The bar samples were used as transverse-type piezoelectric transformer elements. The specimens were made in disks of 8 × 0.8 mm and bars of 120 × 26 × 3 mm.

Journal ArticleDOI
K. M. Leung1, S. T. Liu1, J. Kyonka1
TL;DR: In this article, the electrostrictive effect of a barium doped PZT paraelectric ceramic using a sensitive capacitance dilatometer at room temperature was observed.
Abstract: This paper reports an observation of the electrostrictive effect of a barium doped PZT paraelectric ceramic using a sensitive capacitance dilatometer at room temperature. This sintered material was found to exhibit a large electrostrictive coeffiecient Q12 of − 0.27 m4/C2 which is five times as large as that of single crystal BaTiO3. Comparison with a very strong piezoelectric PLZT at the same field strength indicates that Ba: PZT is a potentially useful material for transducer application.

Patent
23 Apr 1980
TL;DR: In this paper, a polymeric piezoelectric film such as polyvinylidene fluoride film was coupled with an additional layer having a thickness specified in relation to the wavelength of sound waves within the additional layer at the free resonant frequency of the polymeric PE.
Abstract: Electro-acoustic transducer element having its resonant frequency in a lower frequency range advantageously usable for diagnostic purposes comprises a polymeric piezoelectric film such as polyvinylidene fluoride film being coupled with an additional layer having a thickness specified in relation to the wavelength of sound waves within the additional layer at the free resonant frequency of the polymeric piezoelectric film, the additional layer having an acoustic impedance related to the acoustic impedance of the polymeric piezoelectric film.