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Showing papers on "Piezoelectricity published in 1977"


Journal ArticleDOI
TL;DR: Using a standard RF coil and a transient recorder, it was found that small cracks in quartz and tourmaline single crystals produce exponentially-decaying RF transients with a time constant of about 10/sup -5/ s as mentioned in this paper.
Abstract: Fracture of quartz-bearing rocks and other hard piezoelectric materials is associated with radio frequency (RF) electromagnetic emission that can be readily detected in the laboratory. Using a standard RF coil and a transient recorder it was found that small cracks in quartz and tourmaline single crystals produce exponentially-decaying RF transients with a time constant of about 10/sup -5/ s. Failure of quartz-bearing rocks generates longer and more complex transients, presumably due to interference of radiation emitted by numerous piezoelectric crystals as a result of the sudden drop in piezoelectric field accompanying the release of stress. The spectral content of these transients depends on grain size, shifting to higher frequencies as grain size decreases. This fracture-related emission has a variety of potential geophysical applications ranging from monitoring cracks in rock deformation experiments to studies of electromagnetic effects associated with earthquakes, hydraulic fracture and mine failure.

256 citations


Journal ArticleDOI
TL;DR: In this paper, single crystals of fresnoite Ba 2 TiSi 2 O 8 with diameters up to 2 cm and lengths of 7 cm have been grown by Czochralski technique from a stoichiometric melt.

72 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured the elastic constants, temperature coefficients of elastic constants and thermal expansion coefficients in Ba2Si2TiO8 and found that the largest values of k′31 and k′15 are 0.13 and 0.28, respectively, and the minimum value of [Tfr]L is −47 ppm/°C.
Abstract: All the elastic constants, temperature coefficients of elastic constants, and thermal‐expansion coefficients in Ba2Si2TiO8 were measured. Signs of the piezoelectric constants d31 and d15 were determined to be positive. From the calculations of the orientational dependences on the electromechanical coupling factors k′31 and k′15 and the temperature coefficient of resonance frequency [Tfr]L in the length‐extensional mode, it was found that the largest values of k′31 and k′15 are 0.13 and 0.28, respectively, and the minimum value of [Tfr]L is −47 ppm/°C. Surface‐acoustic‐wave analysis for the crystal showed that the SH‐mode piezoelectric surface wave has a piezoelectric coupling constant, k2=0.0053, larger than that of quartz, and a temperature coefficient of delay Tτ=+38 ppm/°C for the Y‐propagation direction on the X‐cut surface, smaller than that of LiNbO3.

52 citations


Journal ArticleDOI
TL;DR: In this article, preliminary pyroelectric and piezoelectric results obtained with commercial films of nylon 11 were presented, and the results of dielectric-constant measurements in the temperature range 20−130°C were also presented.
Abstract: This paper describes preliminary pyroelectric and piezoelectric results obtained with commercial films of nylon 11. The results of dielectric‐constant measurements in the temperature range 20–130 °C are also presented. Nylon 11 films show quite high pyroelectricity and the evidence indicates that there is probably dipole orientation in crystalline regions. Charge injection or volume polarization, as well as dipole orientation, was shown to contribute to the pyroelectricity unless the sample was thoroughly relaxed.

46 citations


Journal ArticleDOI
TL;DR: In this paper, the e22, e33, and e15 second-order piezoelectric stress constants, several third-order PDEs, and the cD11 and cD33 elastic stiffness constants are reported for lithium niobate from experiments with input strains from 7×10−4 to 8× 10−3 produced by the elastic impactloading method.
Abstract: Determination of the e22, e33, and e15 second‐order piezoelectric stress constants, several third‐order piezoelectric stress constants, and the cD11 and cD33 elastic stiffness constants are reported for lithium niobate from experiments with input strains from 7×10−4 to 8×10−3 produced by the elastic impact‐loading method. Measurements of the e33 constant were made on a large number of samples to establish sample uniformity. The differences were found to be less than 1%. The present value of e33 is higher than that reported in previous work and appears to call for a revision of the accepted value along with that of the elastic constant cE33. The third‐order piezoelectric stress constants are readily detectable, but the values determined in the present investigation are limited in accuracy due to the relatively low strains which could be applied to the samples before conductivity became excessive.

39 citations


Journal ArticleDOI
TL;DR: In this paper, a one-dimensional composite acoustic resonator model based on the piezoelectric properties of a quartz crystal coated with electrodes of different materials is considered. And the difference between the theoretical resonant frequencies, as calculated from the various models, is discussed.
Abstract: In this paper a quartz crystal coated with electrodes of different materials is considered as a one‐dimensional composite acoustic resonator. The piezoelectric properties of quartz are incorporated in the model. The model leads to a transcendental equation from which the resonant frequencies can be calculated. It will be shown that earlier develolped models can be derived from this more general model by making the proper approximations. The difference between the theoretical resonant frequencies, as calculated from the various models, is discussed. To express this difference a systematic error is defined which proved to be negligable for small mass loading, corresponding to a relative frequency shift <1%, and in the case independent of the electrode material. In case there is a larger mass loading, the discrepancy between the previous models and the model presented in this paper can be of the order of 5%–10%, depending on the properties of the electrode material, i.e., the acoustic impedance and on the ra...

38 citations


Journal ArticleDOI
TL;DR: In this article, it was concluded that piezoelectric fabrics, which would be evidence of paleoelectrics currents, probably do not exist, and therefore they cannot be used as evidence of the existence of a paleolectric current.

36 citations




PatentDOI
TL;DR: In this paper, a method of reducing the resonant frequency of a conventional piezoelectric transducer includes the step of radially slotting the substrate of the transducers.
Abstract: The resonant frequency of a conventional piezoelectric transducer having predetermined dimensions and a fundamental nodal diameter is reduced while maintaining the overall predetermined diameter and fundamental nodal diameter of the transducer. A method of reducing the resonant frequency of a conventional piezoelectric transducer includes the step of radially slotting the substrate of the transducer.

24 citations


Journal ArticleDOI
TL;DR: A parametric matrix is derived to characterize stress generated electric potentials (SGP) in Haversian bone that substantially agrees with experiment, whereas the commonly accepted C6 hexagonal piezoelectric matrix does not.

Journal ArticleDOI
TL;DR: Using a suitable model for the orientation of the collagen fibrils in the osteon system, the piezoelectric constants of the mineralized fibril, including the groundsubstance in dried bone, can be calculated from approximately local charge measurements.

Patent
Alvin E. Brown1
25 Aug 1977
TL;DR: In this paper, a high temperature ultrasonic transducer is described in which a piezoelectric crystal is held in contact with an acoustical diaphragm by a spring which also electrically couples the back face of the crystal to an electrical signal source.
Abstract: A high temperature ultrasonic transducer is described in which a piezoelectric crystal is held in contact with an acoustical diaphragm by a spring which also electrically couples the back face of the crystal to an electrical signal source. An oil film between the diaphragm and crystal provides an acoustical coupling. Air is used to insulate the spring electrical connection from the wall of the transducer.

PatentDOI
Kohji Toda1
TL;DR: An ultrasonic wave transducer which can generate a convergent ultrasonic sound beam is described in this paper, where the transducers consist of liquid contained in a housing, a piezoelectric material in said liquid, and an interdigital electrode arranged on the surface of said piezellectric materials, an alternating voltage being applied to said inter digital electrode.
Abstract: An ultrasonic wave transducer which can generate a convergent ultrasonic sound beam. The transducer comprises liquid contained in a housing, a piezoelectric material in said liquid, and interdigital electrode arranged on the surface of said piezoelectric material, an alternating voltage being applied to said interdigital electrode.

Journal ArticleDOI
TL;DR: In this paper, a method of shortening the transient response of a piezoelectric transducer is described, which can be applied to thickness mode transducers of arbitrary electromechanical coupling.

Patent
10 Jun 1977
TL;DR: In this article, a piezoelectric crystal element comprising a member of monocrystalline material of symmetry class 32 has two force introduction surfaces essentially parallel to a crystallographic ''a''-axis but inclined with respect to the ''c`-axis so as to intersect the latter at a specific angle e.g. 10° to 40°.
Abstract: A piezoelectric crystal element comprising a member of monocrystalline material of symmetry class 32 has two force introduction surfaces essentially parallel to a crystallographic `a`-axis but inclined with respect to the `c`-axis so as to intersect the latter at a specific angle e.g. 10° to 40° to considerably reduce over a desired temperature range the temperature dependence of transverse of antiaxial shear sensitivity.


Journal ArticleDOI
TL;DR: In this article, the theory of the longitudinal technique for sandwich specimens of ∼1 to 10×3×3 mm which are cemented between two fused quartz rods to form a one-half-wavelength unit was developed.
Abstract: The piezoelectric composite oscillator vibrating either in the longitudinal or torsional mode enables the mechanical damping, strain amplitude, elastic modulus, and piezoelectric modulus of a specimen to be determined rapidly and accurately. Previously the technique has been developed for specimens of a length equal to a mutliple of half‐wavelengths requiring a specimen size of ∼80×3×3 mm for 40 kHz. In this paper we develop the theory of the longitudinal technique for sandwich specimens of ∼1 to 10×3×3 mm which are cemented between two fused quartz rods to form a one‐half‐wavelength unit. We demonstrate the sandwich specimen technique by determining the compliance (S1111) of a 〈100〉 KCl single crystal without using its density and find that this value is in agreement with the published result. The equations for the ideal transformer ratio and strain amplitude for the sandwich specimen are confirmed experimentally by measuring the voltage from an α quartz specimen cemented between rods of α quartz, 〈110〉 ...

Patent
27 Apr 1977
TL;DR: A sand transport detector which detects the discrete impingements of sand particles on an elongated probe member inserted into the sand is presented in this article, where a piezoelectric transducer element is cemented to the probe and produces an output signal when impingement occurs.
Abstract: A sand transport detector which detects the discrete impingements of sand particles on an elongated probe member inserted into the sand A piezoelectric transducer element is cemented to the probe and produces an output signal when impingement occurs With an electronic circuit coupled to the transducer, an indication of sand transport may be obtained

Journal ArticleDOI
TL;DR: The elastic moduli, their temperature derivatives, and the dynamic piezoelectric constants of trigonal potassium bromate, point group 3m, were measured by ultrasonic methods.
Abstract: The elastic moduli, their temperature derivatives, and the dynamic piezoelectric constants of trigonal potassium bromate, point group 3m, were measured by ultrasonic methods. The coupling coefficient k, for longitudinal waves which propagate parallel to the threefold axes is 0.58. As the damping coefficient for these waves is extremely small, even at high frequencies up to 100 MHz, trigonal potassium bromate is preferentially suitable for highly efficient generators and sensors of ultrasonic waves. The dielectric constants are relatively small and no disturbing electric conductivity occurs as, for example, in lithium iodate. Therefore this material is superior to most other crystals in its use for such devices. All thermoelastic constants are negative, and it is not possible to cut a crystal with temperature-independent properties.


Patent
Robert A. Kellen1
31 Oct 1977
TL;DR: In this article, a piezoelectric monolithic crystal filter operating in the trapped energy mode and having a capacitor plated on the wafer within energy coupling distance of the main electrodes has its output response improved by trapping wave energy, at the frequencies of the primary electrodes, engendered by the capacitor.
Abstract: A piezoelectric monolithic crystal filter operating in the trapped energy mode and having a capacitor plated on the piezoelectric wafer within energy coupling distance of the main electrodes has its output response improved by trapping wave energy, at the frequencies of the main electrodes, engendered by the capacitor and conducting such energy to the edges of the piezoelectric wafer where it is dissipated. Such energy is therefore not coupled into the filter structure and does not appear as an undesirable response.

Journal ArticleDOI
TL;DR: In this article, the low-frequency voltage and pressure sensitivity of piezoelectric right circular cylinders is derived for three common polarization schemes, and the acoustic pressure on the three major surfaces is considered variable, thereby allowing for any configuration of shielding.
Abstract: The low‐frequency voltage–pressure sensitivity of piezoelectric right circular cylinders is derived for three common polarization schemes. The acoustic pressure on the three major surfaces is considered variable, thereby allowing for any configuration of shielding. Derived sensitivities are illustrated for a common piezoelectric ceramic material (Clevite PZT 4).

Journal ArticleDOI
TL;DR: A theoretical model of an electroelastic continuum has been applied in this paper to the problem of electrodynamic phenomena (piezoelectricity, electrostriction, etc.) associated with earthquakes.
Abstract: A theoretical model of an electroelastic continuum has been applied in this paper to the problem of electrodynamic phenomena (piezoelectricity, electrostriction, etc.) associated with earthquakes. In such a model the coupling between electric and mechanical fields expresses itself by a change of scale of mechanical effects along the electric field, as well as by the additional electric charge created by the earthquake source.

Journal ArticleDOI
TL;DR: An analytical model based on classical piezoelectric theory was used to related electrical effects to the stress-state in a bone cross-section for simple bending of a cylindrical bone shaft, demonstrating that the overall polarities of the polarization volume charge and the induced electrical potential compare favorably with available experimental findings.

Journal ArticleDOI
TL;DR: In this article, a model for an ultrasonic transducer, which allows direct evaluation of the time response by means of digital computing techniques, is described, where the piezoelectric thickness vibrator is represented by lumped elements, i.e., capacitor, inductor, and current-controlled current source.
Abstract: A model for an ultrasonic transducer is described which allows direct evaluation of the time response by means of digital computing techniques. In analogy to the equivalent circuit of a transmission line, the proposed model represents the piezoelectric thickness vibrator by lumped elements, i.e., capacitor, inductor, and current‐controlled current source. Simulation of the model is easily available by applying standard electrical network analysis techniques. The time behavior of an ultrasonic transducer, transmitting or receiving planar longitudinal sound waves, is calculated.

Patent
19 Apr 1977
TL;DR: In this article, a tapped surface acoustic wave (SAW) delay line with time-resolved output is proposed, where the SAW is coupled across an air gap to a bulk acoustic wave in the piezoelectric semiconductor.
Abstract: A tapped surface acoustic wave (SAW) delay line with time-resolved outputssing piezoelectric leaky wave coupling and bulk wave amplification, and having low loss characteristics. A solid piezoelectric semiconductor is placed adjacent to a solid piezoelectric substrate. A pulsed rf input signal is applied to interdigital transducers (IDT) on the substrate. The applied signal launches a SAW in the substrate in a direction parallel to the interface between the substrate and the piezoelectric semiconductor solid. Upon reaching the interface, the SAW is piezoelectrically leaky-wave coupled across an air gap to a bulk acoustic wave in the piezoelectric semiconductor. Reflections of the bulk wave occur at both surfaces of the piezoelectric semiconductor, and piezoelectrically couples back across the air gap to excite a SAW on the piezoelectric substrate. The resultant rf output includes the normal delayed SAW pulse and additional delayed and time-resolved pulses. The amplitude of the bulk wave may be increased using bulk wave amplification.

Patent
21 Mar 1977
TL;DR: In this paper, a spring member is resin bonded to a piezoelectric material body at one end and at the other end carries the oscillating electrode of a Kelvin probe capacitor used for electron work function measurement under vacuum.
Abstract: A spring member is resin bonded to a piezoelectric material body at one endnd at the other end carries the oscillating electrode of a Kelvin probe capacitor used for electron work function measurement under vacuum. The piezoelectric material body can be either a piezoelectric crystal or a piezoceramic. An alternating voltage causes it to vibrate the spring member at a resonant frequency, so that a still greater amplitude of vibration is produced at the electrode. A superimposed d-c voltage is applied to the piezoelectric material body to set the average spacing between the movable reference electrode and the fixed sample electrode. A polyurethane-based resin provides vacuum-proof bonding. The piezoelectric material body and spring are mounted in a tube providing electrostatic shielding. The electrical circuits for a-c excitation and for synchronous detection of displacement currents resulting from differences in contact potential of the respective electrode materials are all located outside the vacuum chamber.

Journal ArticleDOI
TL;DR: In this article, the wave propagation along a crystalline piezoelectric fiber composed of lithium niobate or some other material in the trigonal 3m crystal class is discussed.
Abstract: We discuss wave propagation along a crystalline piezoelectric fiber composed of lithium niobate or some other material in the trigonal 3m crystal class. The crystalline c axis is aligned with the fiber axis. We obtain an analytical description of all the vibrational modes. The method used is to make perturbation expansions about the modes of a hexagonal 6mm piezoelectric fiber, for which exact solutions are known.

Journal ArticleDOI
TL;DR: In this paper, the change in the frequency of piezoelectric resonators caused by a dc electric field applied to their exciting electrodes is studied on the longitudinal mode of rods made of ammonium dihydrogen phosphate (ADP).
Abstract: The change in natural resonant frequency of piezoelectric resonators caused by a dc electric field applied to their exciting electrodes is studied on the longitudinal mode of rods made of ammonium dihydrogen phosphate (ADP). The relative change in frequency for operating frequencies in the range 50-80 kHz is a superposition of linear and quadratic functions of the dc electric field. The linear component, whose order of magnitude per unit electric field intensity is lo-\" V-' m, is interpreted to be the result of a linear change in the magnitude of the elastic constants and the converse piezoelectric effect, both contributing factors being of the same order of magnitude. The nonlinear component accounts for about one percent of the effect at field intensities of the order of lo4 Vm-'. A general formula for the Manuscript received May 5 , 1976. This work was supported by the The author is with York University, Toronto, Ont., Canada. National Research Council of Canada. linear component presented here is used to determine three out of the seven existing components of the electroelastic tensor, their order of magnitude ranging between 10\" and N-'V-'m3 . Thesame formula is further employed both t o predict the magnitude of the relative frequency change with selected rodsat dc electric field intensities not exceeding lo4 Vm-', and t o specify the rods particularly suitable for determination of all relevant components of the electroelastic tensor with maximum possible accuracy.