Showing papers on "Piezoelectricity published in 1983"

Piezoelectric composite thin film resonator

Abstract: A piezoelectric composite thin-film resonator has good temperature stability and resonance response, in a fundamental thickness-extensional vibration mode. Spurious vibrations caused by even-number order harmonic overtones are suppressed. The resonator has a thin film of SiO2 or other materials having a resonant frequency temperature coefficient which is opposite to that of the piezoelectric material. The SiO2 layer is inserted between two thin films of ZnO, CdS, AlN, or other piezoelectric materials. This sandwiched structure is positioned between a pair of electrode films and is supported by an insulative or a semiconductive film which is in turn fixed to a substrate. The thicknesses of the thin films have values such that an overall temperature coefficient of the resonant frequency may be at or near substantially zero. In order to better remove the even-number order harmonics, it is preferable to cover the upper electrode film with a thin film of semiconductor or insulator material.

Recent developments of piezoelectric ceramic products and composites of synthetic rubber and piezoelectric ceramic particles

Abstract: The theory on the dielectric and piezoelectric constants of the composites, with 0–3 connectivity, of synthetic rubber and piezoelectric ceramic particles is derived based on “modified'’cubes model. The dielectric and piezoelectric constants of the composites of chloroprene rubber and ceramic particles of PZT or PbTiO3 are reported. Also the applications of the composites and the piezoelectric ceramic products recently developed at our laboratory are explained.

Dielectric and piezoelectric properties of modified lead titanate zirconate ceramics from 4.2 to 300 K

Abstract: The dielectric and piezoelectric properties (d-p properties) of four kinds of doped lead titanate zirconate piezoelectric ceramics (PZTs) have been measured from 4.2 to 300 K. The d-p properties of the materials converge with decreasing temperature down to liquid helium temperature, even though the properties have large differences at room temperatue. The values of mechanical and electrical quality factors,Q m,Q e, and of the frequency constant,N, of the materials increased at low temperature. It is evident from the freeze out inK′ and the associate temperature: frequency-dependent maxima in tan 5 that the relaxation processes including ferroelectric domain wall motion and thermal defect motion contribute to the d-p properties. The Navy type-III composition has a minimum temperature coefficient of d-p parameters and it is evident that PZT ceramics modified with Fe2O3 can provide good stability and also give the strongest piezoelectric response at liquid helium temperature.

Polymer piezoelectric sensor of animal foot pressure

Abstract: A sensor structure for attachment to the foot of an animal to continuously measure the pressure of the foot against a reactive surface. The sensor structure provides a small flat particularly configured piece of piezoelectric plastic, encapsulated to protect it and interconnected electrically with telemetry and analyzing apparatus. Plural sensors may be used in various parts of a foot to determine local pressures. The sensed pressure may be recorded and annunciated by various known means to aid analysis of foot and limb activity and general animal physiology.

PVF2 polymers: Ferroelectric polarization and piezoelectric properties under dynamic pressure and shock wave action

Abstract: Polyvinylidene Fluoride PVF2 presents a strong piezoelectric activity under specific conditions of crystallization and polarization. Studies of the ferroelectric polarization, of the physical and piezoelectric characteristics and of the behavior of PVF2 under dynamic pressure are of fundamental interest. The piezoelectric activity of PVF2 depends on the polarization process as it is presented in the studies of the hysteresis loops P(E) (P: polarization, E: electrical field). The remanent polarization attains 10 μC/cm2 for bi-axially stretched films from Rh˘ne Poulenc Films. Results obtained on uniaxial stretched films from Pennwalt Corporation are reported. Properties under static pressure are presented. Applications to ballistic transducers are described. The dynamic behavior of piezoelectric PVF2 under shock wave is surveyed. Study of shock loaded electric energy released from PVF2 films will be reported. Results with PVF2 transducers for weak or strong shock waves and applications of PVF2 to s...

Internal electrode piezoelectric ceramic actuator

Abstract: A piezoelectric ceramic actuator element with multilayer internal electrodes has been investigated. It was fabricated by multilayer ceramic capacitor techniques. An individual internal electrode has the same area as the element cross section area. It has no piezoelectric inactive part, so that it shows original strain/field characteristics in the material. It can be driven by a relatively low votlage (< 200V) and has a semi-permanent life under successive voltage pulse application. Typical properties of the element using 0·65Pb(Mg1/3Nb2/3)O3-0·35PbTiO3 ceramics are 8·7 × 10−4 strain, over 3·5 × 107 N/m2 force, within 100 μsec response time and 70% electromechanical couplig factor driven by 1 × 106 V/m field.

Piezoelectric properties of biological polymers

Abstract: Piezoelectricity and pyroelectricity in wool and hair were observed by Martin early in 1941. The piezoelectric effect in wood was investigated in detail by Bazhenov (1961). Both converse and direct effect of shear piezoelectricity in wood was demonstrated by Fukada (1955). Bending piezoelectricity in bone was first discovered by Yasuda (1953). Shear and longitudinal piezoelectricity in bone and tendon was quantitatively investigatged by Fukada & Yasuda (1957, 1964).

Piezoelectric and Dielectric Properties of Composites of Synthetic Rubber and PbTiO3or PZT

Abstract: The piezoelectric and dielectric properties, particularly those important for hydrophone application, of flexible composites of synthetic rubber and piezoelectric ceramic particles are reported in this paper. Also a theoretically derived "modified" cubes model is presented, which generalizes the parallel, series and cubes models.

Piezoelectricity and pyroelectricity in polyvinylidene fluoride: Influence of the lattice structure

Abstract: Piezoelectric and pyroelectric responses of β‐phase (Phase I) polyvinylidene fluoride are predicted for a model system of polarizable point dipoles. The model incorporates the influence of the orthorhombic crystal structure by including the dependence of the internal electric field on the lattice parameters. Strong anisotropy in the piezoelectric response under uniaxial stress is predicted as a consequence of the orthorhombic lattice structure. Predictions are found to be in reasonable agreement with room‐temperature experimental data.

Photoacoustics, new methods to study optical properties of dislocations ?

Abstract: The principles of the so-called photoacoustic methods are briefly described and the three main types of experimental approaches are reviewed : microphone and closed cell ; piezoelectric transducer and open cell ; mirage effect detection of photothermal deflection. Such methods being sensitive to non-radiative transitions are complementary to photoluminescence. The main advantage of photoacoustics over regular absorption is a good sensitivity due to detection over a "black background" just as in photoluminescence excitation. For instance, absorbance values as small as 10-6cm-1 have been detected for non-radiative centers. Besides spectroscopy, photoacoustic methods can also be used for topography with depth profiling capabilities. Though the applications of these methods to optical properties of dislocations is still in its enfancy, the first few promizing results in the literature shall be reviewed.

Temperature dependence of the resonant frequency of electroded contoured AT-cut quartz crystal resonators

Abstract: A system of approximate equations recently obtained for the determination of thermal stresses in electroded piezoelectric plates is applied to contoured AT‐cut quartz crystal resonators. The changes in resonant frequency resulting from the thermally induced biasing stresses and strains, the temperature derivatives of the fundamental elastic constants of quartz, and the very important temperature dependence of the thickness piezoelectric constant for the AT cut are determined from an equation for the perturbation of the eigenfrequency of the piezoelectric solution due to a bias. The changes in resonant frequency with temperature are calculated for the fundamental and some of the harmonic overtone thickness modes, which were obtained in a recent analysis of overtone modes in contoured crystal resonators. The influences of both the contouring and the electrode size are clearly exhibited.

Piezoelectric Polymers and Their Applications

Abstract: Properties and applications of piezoelectric polymers are reviewed. A typical piezoelectric polymer polyvinylidene fluoride exhibits strong piezoelectricity when polarized and is now commercially available. It can be prepared in large thin films and possesses many more features than conventional piezoelectric ceramics. It has been applied to various transducers and has great future potential.

Piezoelectric transducer notably for pressure measurement

Abstract: In a pressure transducer of the piezoelectric type, a resonator (10) is made up of a pellet (16) mounted inside an element designed to be subjected to the action of a pressure on its exterior face (18). The pellet (16) and the element (12) are cut in the same quartz block, using a cut which provides two vibration modes. The forces resulting from the external pressure are transmitted to the edge of the pellet (16) by connecting bridges (22, 23) whose orientation is chosen so that one of the vibration modes has maximum sensitivity to the forces while the other mode has a practically zero sensitivity.

Some aspects of the physics of piezoelectric ceramics

Abstract: This paper discusses some aspects of the physics of piezoelectric ceramics which depend considerably on the presence of mixed ferroelectric phases in these materials. The data which are available and problems which are yet to be studied may be divided into several categories. A more complete understanding of problems arising in some of these categories awaits growth of good quality single crystals of lead zirconate titanate (PZT).

Surface acoustic wave device with impedance matching network formed thereon

Abstract: The surface acoustic wave device comprises an elastic substrate, a piezoelectric film deposited on the elastic substrate, and transducers and matching circuits both provided on the piezoelectric film or along the interface between the piezoelectric film and the elastic substrate.

Elastic and dielectric nonlinearities of piezoelectric ceramics

Abstract: Piezoelectric ceramics are rather exactly specified for small signal applications by the linear elastic, dielectric and piezo electric coefficients. However, an unambiguous characterization of ceramics, which are to be operated at high mechanical or electric power level, cannot be given by these means. There is still an urgent need to improve the characterization of piezoelectric ceramics.

Piezoelectric resonator chip and trimming method for adjusting the frequency thereof

Abstract: A piezoelectric resonator chip which includes a piezoelectric chip plate and a pair of electrode patterns which is formed on the opposite surfaces of the piezoelectric chip plate, the electrode patterns face each other through the piezoelectric chip plate. At least one of the electrode patterns has an adjuster pattern which includes a narrow cutting pattern and a separation pattern which is connected to the electrode pattern through the cutting pattern and which faces the other electrode pattern.

Integrated magnetostrictive-piezoelectric-metal oxide semiconductor magnetic playback head

Abstract: A thin-film magnetic recording playback head is disclosed wherein mechanically coupled films of a magnetostrictive material and of a piezoelectric material are deposited on a substrate together with a solid state amplifier which is coupled to the piezoelectric film. In operation, localized magnetic patterns on a recording medium induce stress in the magnetostrictive film, which in turn induces in the piezoelectric film a corresponding electrical polarization of non-equilibrium charge density, having a potential associated therewith which is applied to the solid state amplifier.

Internal Electrode Piezoelectric Ceramic Actuator

Abstract: An internal electrode multilayer piezoelectric ceramic actuator element has been investigated. An individual internal electrode has the same area as the element cross section area. It has no piezoelectric inactive part, so that it shows strain/field characteristics similar to plain piezoelectric ceramics. It can be driven by a relatively low voltage (200 V) and has a semipermanent life under a successive voltage pulse application. Typical properties of the element using 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 ceramics are 8.7×10-4 strain, over 3.5×107 N/m2 stress and within 100 µsec response time driven by 1×106 V/m field.

Surface acoustic wave device using an elastic substrate and an aluminum nitride piezoelectric film

Abstract: A surface acoustic wave device comprises an elastic substrate having a major surface with a given crystal orientation and having a positive temperature coefficient of delay (TCD), and AlN film deposited on the elastic substrate so that piezoelectric axis of the AlN film has a predetermined direction with respect to the major surface of the elastic substrate having a negative TCD, and electrodes provided on the AlN film or between the elastic substrate and the AlN film.

Surface wave motor utilizing supersonic wave vibration

Abstract: PURPOSE: To enable to hold the frequency of an input power source at the optimum value by detecting the vibrating state of an elastic unit by utilizing a section which does not contribute directly to the vibration of a piezoelectric element. CONSTITUTION: A segment electrode group made of a silver or the like is coated on a ring-shaped piezoelectric element. When an AC voltage of the prescribed frequency displaced out of phase of 90° is applied between an input terminal R-G and an input terminal L-G, a bending vibration occurs at a ring-shaped piezoelectric unit and a ring of an elastic unit, and a rotor is rotated. A terminal S is provided at the electrode 3b of the section which does not contribute directly to the vibration of a piezoelectric unit, and a voltage produced by the vibration is detected as a monitoring voltage from the terminal S. The optimum frequency of an input power source is determined by the monitoring voltage. COPYRIGHT: (C)1984,JPO&Japio

Laminated type piezoelectric body

Abstract: PURPOSE:To obtain a laminating type piezoelectric body having the stable quantity of displacement and excellent durability by limiting the degree of surface roughness and degree of swell of a piezoelectric element used for a laminate. CONSTITUTION:The degree of swell of a piezoelectric element 1 for a laminate A is decided to be less than 0.07%. When the degree of swell exceeds 0.07%, the quantity of displacement of the laminate A reaches 45 micron or less, and the laminate cannot be used when it is employed as a driving source for an injector. Partial stress by swells is generated in each piezoelectric element 1 under the state in which high load is applied in the axial direction of the piezoelectric body A. When the laminate is used as the driving source for the injector, the degree of surface roughness is decided to be less than five micron. That is, the quantity of displacement is made smaller than 45 micron and the laminate cannot be employed substantially on five micro or more, and fine cracks are generated in the piezoelectric element and durability is deteriorated in the same manner as in the case of the degree of swell of 0.07% or more.

Method and device for polarizing ferroelectric materials

Abstract: Method and means for polarizing ferroelectric materials up to a predetermined polarization level include the application of an electric field E to these materials. According to this method the ferroelectric material is subjected to an alternating electric field E, the frequency of which ranges from about 0.001 to 1 Hz, and which is made to increase gradually and in a cyclic way between 0±E N , E N being slightly in excess of the coercive force E C of said material. Simultaneously, the intensity i of the current traversing the material (2) is measured as a function of the applied field (E) using a unit of visualization, until a stable curve i=f(E) is attained. The invention is particularly suitable for obtaining a stable polarization of ferroelectric polymers, copolymers, crystals, and polycrystals, with the objective of using the piezoelectric and/or pyroelectric properties of these materials.

Grooved piezoelectric ceramic resonator with two poling directions

Abstract: An improved piezoelectric ceramic resonator in which spurious vibration other than that in a longitudinal direction of a piezoelectric ceramic plate is suppressed. The directions of polarization of the rectangular piezoelectric ceramic plate at opposite sides of a concave groove provided in the piezoelectric ceramic plate are different from each other, and are unequal in magnitude. A portion of the plate between the oppositely polarized portions is not polarized in any predetermined direction. The resulting arrangement improves a spurious characteristic of the piezoelectric ceramic resonator, and also rectifies an imbalance in selectivity characteristic between a high frequency side and a low frequency side, when the resonator is used in an electrical filter.

The static and dynamic strength of piezoelectric materials

Abstract: Data on the static and the dynamic strength of piezoelectric ceramics and single crystals are presented together with results of fractographic observations of the fracture surfaces. Fracture analysis theory is combined with these data to propose a mechanism for the observed differences in static and dynamic strength.

Method of making electromechanical transducers using improved flexible composite piezoelectric material

Abstract: A method of making flexible composite piezoelectric materials exhibiting hydrostatic response and having a stable response over time is given A prepolymer material is combined with a piezoelectric material and polarized by applying an electric field while inducing an electric dipole in the piezoelectric material, typically by applying hydrostatic pressure or changing the temperature To ensure stable response characteristics, the polymer material is chosen to have a shear modulus of less than 20 pounds per square inch To help ensure good contact between the piezoelectric material and the polymer material, controlled shrinkage may be induced in the composite materials by heat or the removal of a volatile material The prepolymer material desirably has an electrical resistivity greater than 1010 ohm/meters Typical piezoelectric materials include lithium sulfate and tartaric acid Typical polymer materials include RTV rubber, urethanes, and polybutadienes, and may be in the form of oligomers