Thin Piezoelectric Ceramic Plate Research Articles

Dynamic response of metals under high-intensity pulsed ion beam irradiation for surface modification

A piezoelectric transducer based on lead–zirconte–titanate (PZT) piezoelectric ceramic thin plate was applied to characterize the stress waves in titanium targets under high-intensity pulsed ion beam (HIPIB) irradiation at a peak accelerating voltage of 350 kV and an ion current density up to 400 A/cm 2 with pulse duration of about 150 ns. The magnitude of recorded stress wave signals was increased along with the irradiation intensity, presenting a slow growth with a value below 100 V in the range of 200–300 A/cm 2, and then a rapid increase of about four times up to 400 A/cm 2. The measured stress waves were explained by space–time diagram analysis. The generation and propagation of the stress wave can be attributed to the coupled thermal–dynamic effects during HIPIB irradiation onto metallic targets, where the thermal shock due to ultra-fast heating/cooling process and the recoil impulse due to ablation process have a combined contribution to the induced stress waves, dependent on the irradiation intensity. It is indicated that a fast attenuation of stress wave proceeded during its propagation from the irradiated surface to the target/PZT interface. The large amount of energy delivered by the stress wave effectively converted and dissipated into plastic deformation and/or defects formation in target materials. The dynamic response of metallic materials under HIPIB irradiation accounts for the effective surface modification of metals and alloys into a depth well beyond the ion range.

Nondestructive testing in human teeth using a leaky Lamb wave device

A Lamb wave interdigital transducer mounted on a layered substrate composed of two plates, a thin piezoelectric ceramic plate and an acrylic plate, operating at a liquid–solid boundary, is investigated for ultrasonic nondestructive testing of the layer thickness in human teeth. A higher-order mode having a phase velocity higher than the longitudinal wave velocity in the human teeth can be used for nondestructive testing. In the combination of the two layers, the fourth mode of leaky Lamb wave is most favorable for a frequency-controllable radiation angle of an ultrasound beam into a water layer as an acoustic coupler. In the configuration of an acoustic delay line, the layer-thickness measurement in vivo, evaluated from the time interval between two reflected ultrasound echoes, is successfully realized under a thin water layer as the acoustic coupler.

Operational Performance of A0-mode Lamb Wave Interdigital Transducers Under Water-Loaded Condition

The operational performance of an A0-mode Lamb wave interdigital transducer is described in a delay line structure. The delay line is composed of two interdigital transducers (IDTs) on a thin piezoelectric ceramic plate, under the air- or water-loaded condition. The A0-mode Lamb wave device has two frequency ranges in the forms of nonleaky and leaky Lamb waves. The boundary frequency is related to the longitudinal wave velocity in water. The basic performance of the A0-mode delay line is presented with measured results in the vicinity of the transition region, where the A0-mode Lamb wave velocity is near the longitudinal wave velocity in water. The A0-mode IDT operates efficiently as an underwater transducer with a shallow radiation angle in the operation region as the leaky wave.

Piezoelectric ceramic rectangular transducers in flexural vibration

Based on the equivalent elastic method and coupled vibration theory, an analytic method is presented to study the flexural vibration of rectangular transducers consisting of piezoelectric ceramic thin plates. By introducing a mechanical coupling coefficient, the flexural vibration of the piezoelectric ceramic rectangular thin plate is reduced to two simple, one-dimensional flexural vibrations of narrow piezoelectric ceramic strips. The resonance frequency equations for the piezoelectric ceramic rectangular thin-plate transducers in flexural vibration are derived under the free and simply supported boundary conditions analytically. The relationship between the resonance frequency and the flexural vibrational order, the geometrical shape, and the dimensions of the piezoelectric ceramic rectangular thin-plate transducer is analyzed. It is demonstrated that the one-dimensional vibrational theory for the flexural vibration of a narrow piezoelectric ceramic strip and the stripe-mode flexural vibrational theory for the piezoelectric ceramic rectangular thin plate can be derived directly from the theory obtained in this paper. Experimental results show that the measured resonance frequencies of the piezoelectric ceramic rectangular thin-plate transducers in flexural vibration under free-boundary conditions are in good agreement with the calculated results. The method presented in this paper can be used in the resonance frequency analysis of vibrating systems in coupled vibration.

Moving-Speed Measurement Using Leaky Lamb Wave Interdigital Transducers

A technique for measuring the moving target speed is described using an ultrasound device, composed of two leaky Lamb wave interdigital transducers (IDTs) and a thickness-mode transducer on a thin piezoelectric ceramic plate. The thickness-mode transducer located between the two IDTs radiates an ultrasound beam into a liquid in the thickness direction of the piezoelectric substrate. The IDT functions as a detector of the ultrasound signal reflected in an oblique direction from a moving medium in the liquid. The reflected delayed-output has a frequency shift via a Doppler effect, corresponding to the moving speed of the reflection object. Basic performances of the device with two IDTs and the central thickness-mode transducer and the measured results of the moving speed of a metal disk are presented for the first antisymmetrical Lamb wave mode with the highly dispersive property.

Measurement of Moving Speed Using a Leaky Lamb Wave Device

A technique for measuring the moving speed of a tested object is described using a leaky Lamb wave device composed of two interdigital transducers (IDTs). The IDT on a thin piezoelectric ceramic plate radiates as an ultrasound beam into a liquid and also operates as a detector of the ultrasound signal reflected from a moving medium, at a liquid-solid interface. The delayed output has a frequency shift via a Doppler effect, corresponding to the moving speed of the reflection object. Basic performances of the leaky Lamb wave device and the measured results of the moving speed of a metal disk are presented.

MEASUREMENT OF ELECTRORHEOLOGY EFFECT OF FERROELECTRIC LIQUID CRYSTAL USING A SHEAR-HORIZONTAL WAVE DELAY LINE OSCILLATOR

An electrorheology (ER) effect of a ferroelectric liquid crystal (FLC) is described on the basis in numerical analysis and experiment. Propagation characteristics of a shear-horizontal (SH) wave in a liquid crystal layer between a piezoelectric ceramic thin plate and a glass thin plate is numerically analyzed. The phase velocity of the SH wave depends predominantly on the viscosity of the FLC. The ER effect is measured using a SH wave device under the construction of delay line oscillator. The observed DC electric field dependence of oscillation frequency under the use of a helical structure of FLC is related to the observed microscopic result. This method has the advantage of simplicity and a small amount of liquid sample for evaluating the ER effect of the FLC.

Mechanical Displacement Measurement Using a Leaky Lamb Wave Delay Line Oscillator

A measurement technique for mechanical displacement using a liquid delay line oscillator is described. The delay line is composed of a leaky Lamb wave device with two interdigital transducers (IDTs), a liquid cavity as the propagation medium for an ultrasound beam and an amplifier connected between two IDTs. The IDT for leaky Lamb waves functions as a longitudinal wave radiator or a detector of a reflected ultrasound beam from the surface of a wall in the liquid cavity. The two lowest modes, S0 and A0, propagating in a thin piezoelectric ceramic plate are useful for constructing the leaky wave transducer because of high transducer efficiency. The acoustic delay length changes with mechanical displacement, which results in a change of oscillation frequency. The basic performance of the delay line oscillator is presented with the results of measurements in two operating modes, S0 and A0.

Lamb Wave Propagation Characteristics and Transducer Performances in Layered Substrate Composed of Piezoelectric Thin Plate and Glass Thin Plate

In a layered substrate composed of a piezoelectric ceramic thin plate and a glass thin plate, Lamb wave propagation characteristics and operation performances of an interdigital transducer (IDT) are described. The numerical analysis results of Lamb wave phase velocities in the form of a function of the product of the frequency and the thickness of the piezoelectric ceramic plate are in good agreement with the measured velocities for various thickness ratios of the two plates used as layered substrates. The electromechanical coupling constant k2 of the IDT on the layered substrate reaches a peak value when the velocity of the respective Lamb wave mode is almost equal to the phase velocity of the zeroth-order symmetrical mode at fd=0. The above condition for the highest k2 value has been experimentally confirmed for two types of layer-structured devices: the double-layer-type and the separation-type.

Propagation characteristics of leaky Lamb waves in a liquid-loaded double-layered substrate consisting of a thin piezoelectric ceramic plate and a thin glass plate

Operational performance of a leaky wave interdigital transducer on a double-layered substrate composed of two thin plates, a piezoelectric ceramic plate and a glass plate, is described for the purpose of two kinds of transducer functions—one for the effective radiation of underwater ultrasound and the other for liquid sensing. Two parameters, electromechanical coupling coefficient (k2) and mode conversion ratio (C), are evaluated on a two-dimensional p-fd plane as the fundamental factors for the leaky wave transducer, where p is the thickness ratio of the ceramic part and the double-layered substrate, and fd is the product of the frequency (f ) and the total thickness of the substrate (d). For an effective transducer for underwater ultrasound, both k2 and C should be large at a certain operation point of p and fd. The maximum transducer efficiency from the product of k2 and C in the second mode operation in the case of p=0.37 is three times as large as that in the case of a single-layered piezoelectric ceramic plate. For constructing a concise liquid sensing device, on the other hand, a combination of large k2 and small C is required. A condition satisfying the above requirement is recognized in the third mode operation in the case of p=0.55 and fd=3.4 MHz⋅mm. The combination of a piezoelectric ceramic plate and a glass plate is promising for realizing highly functional ultrasound transducers for underwater ultrasound and for liquid sensing.

Velocity Curve Change of Leaky Lamb Waves in a Layered Substrate Induced by Liquid-Loading

A liquid-loading effect on the propagation characteristics of leaky Lamb waves (LLWs) is studied, based on numerical calculations and experiments. A layered substrate consisting of a thin piezoelectric ceramic plate and a thin acrylic plate is used as a propagation guide of the LLW. Interdigital transducers are mounted on the free surface of the ceramic plate and a liquid is in contact with one of the two surfaces of the acrylic plate. Under the condition that the density ratio of water and the acrylic plate is high (0.85), anomalous behaviors of the velocity dispersion curves appear, which do not occur for water-loading on substrates with much higher densities such as ceramic and glass plates. Two typical features of the LLW propagating in the layered substrate are jump of the propagation mode under the influence of the liquid-loading and the modal change of the interaction between two propagation modes. The state change of mode coupling induced by liquid loading is promising for constructing sensing devices.

Measurement of the Sound Velocity in Liquids Using a Leaky Lamb Wave Transducer Composed of a Layer-Structured Substrate

A leaky Lamb wave transducer composed of a thin piezoelectric ceramic plate and a thin glass plate is described for the purpose of measuring the sound velocities in liquids. The propagation characteristics of leaky Lamb waves are numerically analyzed first and the operational characteristics of the transducer are experimentally demonstrated by measuring the frequency dependence of the admittance and the radiation angle of the longitudinal wave into the liquid. The sound velocities in the saline solution of different concentrations are estimated by sweeping the operation frequency. This transducer has an operation mode with a wide frequency range in which three propagation modes of leaky Lamb waves are involved, which is favorable for this application.

Performance of a Leaky Wave Transducer in a Layered Substrate Composed of a Thin Piezoelectric Plate and a Thin Glass Plate

A leaky wave interdigital transducer on a layered substrate composed of two thin plates, a piezoelectric ceramic thin plate and a glass thin plate, is described. The transducer has the function of multiple-mode operation for underwater ultrasound, while retaining sufficient mechanical strength. The calculated results of the phase velocities are confirmed experimentally, including the case of using only a piezoelectric ceramic plate as a substrate. The calculated electromechanical coupling constant and the mode conversion ratio obtained from the phase velocities under two kinds of electrical boundary conditions are also presented along with the experimental results of this type of transducer. The combination of a piezoelectric ceramic plate and a glass plate is a promising method for realizing a highly effective transducer for underwater ultrasound.

Liquid Viscosity Measurement Using Plate Mode Shear Horizontal Waves on a Piezoelectric Ceramic Thin Plate

Numerical analysis results of the propagation characteristics of multiple mode shear horizontal (SH) waves along a piezoelectric ceramic thin plate with liquid loading on one of two boundary surfaces are described. The fractional phase velocity changes for S0, A0 and S1 mode SH waves have linear dependences on the square root of liquid viscosity under the electrically shorted boundary condition of both surfaces of the substrate. The mechanical displacement in the liquid layer decays exponentially with the distance from the substrate-liquid interface. The existing depth of the displacement in the liquid layer increases with liquid viscosity in the form of a linear relationship to the square root of liquid viscosity. The measurement of liquid viscosity using two modes of SH waves is carried out. The measured results for water solutions of glycerol using S0 and A0 mode SH waves show linear dependences between the fractional velocity change and the square root of liquid viscosity, and are consistent with the theoretical values.

Measurement of Vibration Displacement Using a Layered-Structure Leaky Wave Interdigital Transducer

A technique for measuring vibration displacement using a liquid delay line is described. The delay line is composed of two pairs of layered-structure interdigital transducers (IDTs), in combination with a piezoelectric ceramic thin plate and an acryl plate, and a sound-beam-reflecting diaphragm as one wall of a liquid cavity. The IDT functions as a bulk wave radiator or a detector of a signal reflected from the diaphragm. The acoustic delay length changes linearly with the mechanical displacement of the diaphragm. Basic performances of the liquid delay line and measurement results for vibration displacement are presented.

Acoustical Imaging Using a Leaky Wave Transducer Composed of a Piezoelectric Ceramic Plate and an Acryl Plate

An interdigital transducer (IDT) for leaky waves in a layered substrate composed of a piezoelectric ceramic thin plate and an acryl plate is incorporated into a C-mode acoustical imaging system. The transducer performance in the layered structure is described from the viewpoint of ultrasound radiation at an interface between an acryl plate and a water layer. The leaky wave transducer has frequency-dependent radiation angles, corresponding to the leaky wave velocity, under multiple operation modes. The bulk wave direction in a test sample via the longitudinal wave in the water layer is easily controlled by frequency change. A reflection type C-mode acoustical imaging system is successfully demonstrated for nondestructive testing.

Transducer Performance for Leaky Wave in Layered Structure of Piezoelectric Ceramic Thin Plate and Acryl Plate

A leaky wave transducer in the combination of a piezoelectric ceramic thin plate and an acryl plate is described, which functions as a transducer for underwater ultrasound. The operation performance of an interdigital transducer in the layered structure is described from the viewpoint of phase velocity, electromechanical coupling constant, mode conversion efficiency and transducer efficiency. The leaky wave transducer has multiple modes with velocity dispersion. Using the second-order anti-symmetrical mode with high transducer efficiency value, a liquid-delay line oscillation is demonstrated.

Vibrational modes and frequency spectra in piezoelectric ceramic rectangular resonators

An analytical method for the analysis of piezoelectric ceramic rectangular resonators based on the equivalent elastic theory is presented in which the coupling vibrational modes are considered. The resonance frequency equation of rectangular resonators is derived and the natural frequency spectra are calculated. Theoretical analysis shows that the longitudinal vibrational mode of a piezoelectric ceramic slender rod, the planar radial vibrational mode, and the thickness extensional mode of a piezoelectric ceramic thin plate can be obtained from the theory of this paper. Compared with numerical methods, the method presented here is very simple in computing the natural frequencies and analyzing the eigenmodes of piezoelectric ceramic rectangular resonators. The resonance frequencies obtained from the theory of this paper are in good agreement with the measured results.

Surface Acoustic Wave Transducer in a Layered Structure Composed of Thin Piezoelectric Ceramic Plate and Glass

Operation performance of a surface acoustic wave (SAW) interdigital transducer (IDT) in a layered structure composed of a thin piezoelectric ceramic plate and a glass substrate is described in terms of phase velocity, electromechanical coupling constant and mechanical displacement distributions. The numerical results of SAW phase velocities in the form of a function of the product of frequency and thickness of the piezoelectric ceramic plate are in good agreement with the measured velocities of the constructed layer-structured devices. The first-order SAW mode device has an excellent electromechanical coupling constant of greater than 15%, which is favorable for a SAW device exhibiting a satisfactory performance under single-mode operation in a SAW oscillator construction.

Measurement of leaky surface acoustic wave velocity using interdigital transducer in a layered structure composed of piezoelectric ceramic and fused quartz

AbstractAn ultrasonic system for measuring a leaky surface acoustic wave (SAW) velocity is described. A leaky SAW transducer consisting of a piezoelectric ceramic thin plate, an interdigital transducer (IDT), and a fused quartz plate is used in this system. A longitudinal wave which is reradiated from a test sample surface into a water layer is detected as electric signals having different delay times received at two different IDTs placed on a substrate surface. A phase difference between two delayed signals depends on the leaky SAW velocity. It is essential in this measurement method that an incident angle of an ultrasonic beam be nearly equal to the Rayleigh angle. The present method using a layered structure leaky SAW transducer has the advantage of a wider range of detecting SAW velocities, compared to a conventional single‐layer SAW one. Experimental results for a 128° rotated Y‐cut‐X propagation LiNbO3 plate and a glass plate are discussed. The layered structure leaky SAW transducer is useful for nondestructive evaluation of piezoelectric as well as nonpiezoelectric substrates.