Piezoelectric Crystal Research Articles

Contributions to the development of an axisymmetric SAW motor with a stator made from non-piezoelectric material

Surface acoustic wave (SAW) motors offer great potential due to their high blocking forces, high positioning accuracy and simple design. As established SAW motors have a plane stator made by piezoelectric single crystals, designers have nearly no influence on changing material properties like the friction coefficient or brittleness. Furthermore, the efficiency decreases with rising travel length, caused by components of the SAW passing the slider. This article presents the theory of Rayleigh waves on cylindric rods in axial direction of propagation. Based on this, a new axisymmetric motor structure with a stator made from non-piezoelectric base material, which could avoid the problems mentioned above, was analytically characterized. Furthermore, a prototype of a plane SAW motor made from non-piezoelectric steel is presented. SAW were generated by small piezoelectric units made from lead zirconate titanate (PZT). At the working frequency of 3.85 MHz a SAW with an efficiency of 17% was generated. An idling speed of 29 mm s−1 and a blocking force of 0.19 N were measured therewith. Finally, we present a SAW generation by thick film technology. This technology allows the manufacture of piezoelectric units on cylindric rods that are necessary for the mentioned axisymmetric SAW motors. Our prototypes are compared to numeric models.

Symmetry-bridging phase as the mechanism for the large strains in relaxor-PbTiO3 single crystals

Relaxor-PbTiO3 piezoelectric single crystals have been of a great interest, since the discovery of ultrahigh piezoresponse demonstrated in <001> -oriented crystals of the composition at the rhombohedral side of morphotropic phase boundary. It has been proposed that the exceptionally large piezoelectric properties should originate from an electric-field-induced polarization rotation that involves a reversible phase transformation between rhombohedral and tetragonal via monoclinic symmetry. However, this commonly accepted polarization rotation mechanism has its limit in explaining still the excellent piezoelectricity even at a small excitation field far below the coercive field. Here, we show by a comparative study using single crystals from two distinct processing techniques, the polarization rotation has, if ever, little influence on the strain properties of <001 > -oriented rhombohedral relaxor-PbTiO3 single crystals. Instead, they may come from a reversible shear-mode piezoelectric contribution from electric-field-susceptible ‘symmetry-bridging’ unit-cell-level phases, the polarization direction of which spans monoclinic symmetry.

Tunable composite waveguide based on piezoelectric phononic crystal

The acoustic artificial structures with tunable parameters have attracted much research interest in these days. In this paper, we present a tunable composite waveguide based on the piezoelectric phononic crystal shunted by an inductor circuit. A pass band based on local resonance will emerge in the complete band gap through modulating the shunted inductor circuit. This local-resonant pass band can be used to realize a waveguide. Both the work frequency and the shape of this waveguide can be tuned simultaneously by modulating the inductance and the space distribution of the external inductor circuit. For the excellent tunable ability, the proposed tunable composite waveguide could be useful in elastic wave sensors and frequency filters.

Mycobacterium tuberculosis strain H37Rv Electrochemical Sensor Mediated by Aptamer and AuNPs-DNA.

The accurate and rapid detection of Mycobacterium tuberculosis ( M. tuberculosis) is essential for the effective treatment of tuberculosis. In this article, we propose an electrochemical sensor to detect M. tuberculosis reference strain H37Rv. The sensor contains an H37Rv aptamer and oligonucleotides modified with gold nanoparticles (AuNPs-DNA). An H37Rv aptamer screened by our laboratory was used as the recognition probe. The change in frequency shift mediated by AuNPs-DNA in the presence of H37Rv was detected using a multichannel series piezoelectric quartz crystal (MSPQC) system. Three oligonucleotides modified with gold nanoparticles were designed. These oligonucleotides contained 12, 12, and 13 bases that hybridized with the 37-nt H37Rv aptamer. H37Rv aptamer was immobilized on the gold electrode surface by Au-S bonds. A conductive-layer was then formed by sequential hybridization of the aptamer with the three designed AuNPs-DNAs. When H37Rv was present, it specifically bound to the aptamer, resulting in the detachment of AuNPs-DNA from the electrode. The conductive layer was thereby replaced by a nonconductive complex of aptamer and bacteria. These changes were monitored by the MSPQC system. The proposed sensor is rapid, specific and sensitive, the detection time was 2 h. The detection limit was 100 cfu/mL. This sensor would be of great benefit for the early clinical diagnosis of tuberculosis.

A new aptamer/polyadenylated DNA interdigitated gold electrode piezoelectric sensor for rapid detection of Pseudomonas aeruginosa

Rapid detection of Pseudomonas aeruginosa (P. aeruginosa) is of great importance for accurate diagnosis and treatment of infected patients. In this study, a novel method was developed for the selective detection of P. aeruginosa by combing the sandwich type complex of magnetic bead/aptamer/polyadenylated-DNA with the sensitive detection platform of gold (Au) interdigital electrode connected to a multichannel series piezoelectric quartz crystal (Au IDE-MSPQC) system. Here, the magnetic bead (MB) was used as carrier for immobilization of the aptamer of P. aeruginosa. Polyadenylated DNA was bound to the aptamer through complementary strand pairing. When the P. aeruginosa was present in the sample solution, the polyadenylated DNA was replaced by the P. aeruginosa because of the specific interaction between P. aeruginosa and its aptamer. The released polyadenylated DNA strand in the detected solution could adsorb onto the surface of Au IDE by virtue of the strong interaction between adenine (A) and Au IDE, and result in sensitive frequency shift response of the MSPQC sensor. The limits of detection (LOD) of the method were as low as 9 CFU/mL in buffer and 52 CFU/mL in simulated blood sample. The proposed method was successfully applied to the selective detection of P. aeruginosa in blood samples. The constructed sensor is expected to find application for the rapid detection of P. aeruginosa in environment, food and clinical diagnosis.

Calibration of a Piezoelectric Transducer through Laser Measurements and Numerical Simulation

A piezoelectric transducer is an electromechanical sensor which converts electrical energy (voltage signal) to mechanical energy (displacement signal) and vice versa by taking advantage of the piezoelectric crystal. Depending on the physical combination of transducer parts, sensors may have a linear or non-linear response to the input signal. In seismic tests such as ultrasonic non-destructive testing (NDT) methods, analyzing stress wave propagation through the specimen gives an assessment of its condition. The signal attenuation is an important parameter to assess the condition of specimen which can be done by having the displacement signal as an output. However, instead of the displacement signal, the piezoelectric transducer provides the voltage signal as an output. Therefore, to get reliable and accurate results, it is essential to calibrate the transducers. An appropriate calibration results in a suitable Transfer Function (TF) which can be used to properly calculate the displacement signal. In this study, the output displacement of a 1 MHz piezoelectric transducer is measured using a laser vibrometer with a nanometer resolution. Measurements and calculated TF showed at frequencies of 0.1, 1, and 1.5 MHz, TF values are 0.8, 0.08, and 0.2 respectively which is a non-linear relation between displacement (absolute signal) and voltage (relative signal) as it was expected. Then, numerical simulation is implemented as part of this study to simulate all electrical and mechanical components of the piezoelectric transducer. The simulation was verified with the absolute displacement measurements result from the laser vibrometer.

Comparative Study of Acoustic Wave Devices Using Thin Piezoelectric Plates in the 3–5-GHz Range

This paper investigates the applicability of acoustic wave devices using an interdigital transducer placed on a thin piezoelectric crystal plate to the 3–5-GHz range, where significant performance degradation was expected in surface acoustic wave (SAW) devices. Three types of the SAW-like devices were fabricated by using a KrF stepper/scanner, and their performances are compared from various aspects: 1) a 3.5-GHz resonator using a rotated $Y$ -cut LiTaO3 plate attached on a Si substrate; 2) a 5-GHz resonator using a $X$ -cut LiNbO3 plate on a Si substrate; and 3) a 5.4-GHz $A_{1}$ Lamb mode resonator on a free-standing $Z$ -cut LiNbO3 plate. It is revealed that these devices offer excellent performances even in the 3–5-GHz range.

Direct detection of dark matter particles by nonlinear effects in crystal vibrations

The energetic dark matter particles (EDP) of (4 + 1.5) x 1015 eV mass-energy propagating from the central region of the Milky Way galaxy (CMW) are directly detected with the help of half-inch ~10 MHz quartz vibrators. The spectra of acousto-electric vibrations of thin piezoelectric crystal are theoretically calculated, and a nonlinear effect of external frictional influence is taken into account. The EDP produce the changes in the spectra of vibrations under specific orientation of the crystallographic axes toward the CMW. The mechanism of EDP-crystal interaction may be associated with the gravitational influence of EDP and their quantum properties, such as matter waves. The EDP average energy density is 0.71 + 0.29 (GeV/cm3) near Earth, which agrees with the expectations and existing astrophysical bounds of dark matter density in the solar neighborhood. The EDP can transfer their momenta-energy to a media of propagation. The influences of EDP, or naviten, on vibrating atoms are detected from 10 different samples during 5 years. The micro-void tracks of EDP-particles are also observed in the vibrating plates of fuzzed quartz, which appear due to EDP decay inside solid media. The existence of EDP-particles is in agreement with recent detection of the ~1015 eV energy neutrinos from the CMW region.

Piezoelectric–Piezoresistive Coupling MEMS Sensors for Measurement of Electric Fields of Broad Bandwidth and Large Dynamic Range

Electric-field microelectro-mechanical systems sensors with broad bandwidth and large dynamic range are an enabling technology for real-time monitoring of fast transient overvoltage in the power grid. They significantly alter lightning damage and operation faults and therefore help establish a more secure grid. In this paper, we propose a new method and architecture for electric-field sensing, which overcomes the incompatibilities between electric-field measurements of broad spectrum and large dynamic range. Scientifically, this compound structure with coupled piezoelectric effect and piezoresistive effect transduces electric field changes into resistance alterations via internal pressure. This structure has an hour-glass-shaped cavity, which contains a piezoelectric crystal and leaves the piezoresistive membrane vibrating freely. The newly proposed sensors have a broadened frequency bandwidth of up to 100 kHz and a 15-fold improved sensing magnitude. In addition, this sensor decreases the cost by two orders and reduces energy consumption to 0.018%, which makes them readily implantable into electrical appliances in the power grid.

Voltage-Controlled, Nonreciprocal Millimeter-Wave Propagation From Magnetoelastic Membranes Infused With Aligned Nickel Microparticles

Differential Faraday rotation of the linear polarization of millimeter-wave (mmW) Gaussian beams has been observed from a magnetoelastic material system consisting of a silicone membrane that was infused with aligned nickel microparticles, mounted to a piezoelectric annulus, and immersed in a static magnetic field. The piezoelectric crystal was driven near its radial mode of resonance by an ac voltage signal so as to periodically stretch the membrane about the axis of mmW propagation. The stretching modulated the distribution of nickel microparticles and resulted in a change in magnetic properties of the material, specifically the effective Verdet constant. A customized, quasi-optical apparatus was phase locked with the ac driving signal to determine the difference in Faraday rotation due to the stretched and un-stretched states of the membrane.

A push-mode piezo inkjet equivalent circuit model enhanced by diaphragm displacement measurements

This paper reports on ways to better predict droplet ejection velocity of push-mode piezo inkjet technology by upgrading the conventional equivalent circuit model. Calculation results from the traditional model imply that the driving pulse width conditions without ink ejection only periodically exist in the pull-push piezo driving mode. However, ink ejection is actually observed under any pulse width condition. The displacement of the diaphragm with respect to the piezo element input voltage waveform was measured with a highly accurate capacitive displacement gauge to correct for the difference between the actual measurements and calculations. The equivalent circuit model was then modified so that the measured diaphragm residual oscillations could be expressed. We presumed that an actual inkjet printhead contains an effective spring oscillation component, effective actuator mass, and damping component larger than that used in conventional equivalent circuit model calculations. We demonstrated that the difference between the calculated results and actual measurements could be reduced. Modifications to equivalent circuit model are based on the addition of an effective mechanical spring oscillation component having the same function as the ink chamber compliance, an increase in actuator inertance corresponding to the mass of the actuator, and an effective resistance element expressing a damped oscillation.

Time-resolved X-ray reciprocal space mapping of a crystal in an external electric field

A reciprocal space mapping technique with the use of triple-crystal time-resolved X-ray diffractometry has been developed and implemented using a laboratory X-ray source for the first time. This technique allows studying fast processes that occur in a sample under external influences that cause reversible deformations of its crystal lattice. It also allows distinguishing these processes in time and distinguishing different types of crystal deformations caused by these actions. The essence of the technique is to measure time dependences of the intensity for each point of the reciprocal space in the vicinity of the diffraction maximum in three-axis diffraction geometry by subjecting the sample to repeated and structurally identical action of a strong electric field, with the subsequent construction of the time evolution of the two-dimensional reciprocal space map. The time resolution is achieved with the use of a high-speed multichannel intensity analyzer synchronized with a high-voltage source. The results of measuring the reciprocal space maps with a laboratory radiation source with a time resolution of up to 10 ms are demonstrated for a piezoelectric crystal of lanthanum gallium silicate subjected to an external electric field with the field strength 3.08 kV mm−1, which is close to the sample breakdown value.

Nonlocal analytical solution of functionally graded multilayered one-dimensional hexagonal piezoelectric quasicrystal nanoplates

Based on the nonlocal elasticity theory, the static bending deformation of a functionally graded multilayered one-dimensional (1D) hexagonal piezoelectric quasicrystal (PQC) simply supported nanoplate is investigated under surface mechanical loadings. The functionally graded material is assumed to be exponential along the thickness direction. By utilizing the pseudo-Stroh formalism and propagator matrix method, exact closed-form solutions of functionally graded multilayered 1D hexagonal PQC nanoplates are then obtained by assuming that the layer interfaces are perfectly contacted. Numerical examples for six kinds of sandwich functionally graded nanoplates made up of piezoelectric crystals, quasicrystal and PQC are presented to illustrate the influence of the exponential factor, nonlocal parameter and stacking sequence on the phonon, phason and electric fields, which play an important role in designing new composite structures in engineering.

Structure and Properties of Piezoelectric Strontium Fresnoite Glass-Ceramics Belonging to the Sr–Ti–Si–Al–K–O System

Crystallization of strontium fresnoite Sr2TiSi2O8 piezoelectric crystals in Sr–Ti–Si–K–Al–O parent glasses is investigated with the aim of showing the influence of composition and crystallization conditions on the microstructure and piezoelectric properties of the resulting glass-ceramic. All the investigated conditions lead to a surface crystallization mechanism that induces a preferential orientation of crystal growth in the glasses. Near the surface, all the glass-ceramics obtained exhibit (002) planes preferentially oriented parallel to their faces. Deeper in the specimens, this preferential orientation is either kept or tilted to (201) after a depth of about 300 µm. The measurement of the charge coefficient d33 of the glass-ceramic highlights that surface crystallization induces mirror symmetry in the polarization. It reaches 11 to 12 pC/N and is not significantly influenced by the preferential orientation (002) or (201). High temperature XRD shows the stability of the fresnoite phase in the glass-ceramics up to 1000 °C. Mechanical characterization of the glass-ceramics by impulse excitation technique (IET) highlights that the softening of the residual glass leads to a progressive decrease of Young’s modulus in the temperature range 600–800 °C. Damping associated to the viscoplastic transition become severe only over 800 °C.

Giant Piezoelectricity of Ternary Perovskite Ceramics at High Temperatures

AbstractHere, novel ferroelectric ceramics of (0.95 − x)BiScO3‐xPbTiO3‐0.05Pb(Sn1/3Nb2/3)O3 (BS‐xPT‐PSN) of complex perovskite structure are reported with compositions near the morphotropic phase boundary (MPB), and which exhibit a piezoelectric coefficient d33 = 555 pC N−1, a large‐signal coefficient ≈ 1200 pm V−1 at room temperature, and a high Curie temperature TC of 408 °C. More interestingly, this ternary system exhibits a giant and stable piezoelectric response at 200 °C with a large‐signal ≈ 2500 pm V−1, matching that of the costly relaxor‐based piezoelectric single crystals at room temperature. The mechanisms of such giant piezoelectricity and its characteristic temperature dependence are attributed to the spontaneous polarization rotation and extension under an electric field and the MPB‐related phase transition. The findings reveal that the BS‐xPT‐PSN ceramics constitute a new family of high‐performance piezoelectric materials suitable for electromechanical transducers that can be operated at high temperatures (at 200 °C, or higher).

Evaluation of power extraction circuits on piezo‐transducers operating under low‐frequency vibration‐induced strains in bridges

AbstractThe concept of piezoelectric energy harvesting (PEH) provides a promising solution for perpetually running low‐power electronic devices such as wireless sensor networks by harvesting ambient vibrations generated from civil structures such as long span bridges, city flyovers, elevated metro corridors, which are constantly under dynamic loads. However, its successful industrial‐scale deployment on civil structures is still not realised because of the low‐frequency of vibrations (typically &lt;5 Hz) encountered there, coupled with the low levels of voltage generation. The vast majority of PEH‐related studies have only focused on PEH configurations and geometries, Often entailing secondary structures. d31 mode, which is the most natural mode of excitation, has not been investigated in depth for piezo‐patches directly bonded on the main structure. Studies, which have focused on electronic conditioning circuitry, have been restricted to typically high‐voltage and high‐frequency scenarios only. This paper focuses on systematically studying the issues inflicting energy harvesting from the ambient vibrations induced flexural strains civil structures, such as city flyovers, using piezo elements in d31 mode. Vibration measurements are first undertaken from a typical city flyover consisting of steel girders supporting a reinforced concrete (RC) deck. The basic site measurements are employed to perform a laboratory‐based parametric study to investigate the influence of parameters such as vibration frequency, voltage, and circuit components like diodes on PEH. On the basis of the experimental results, it can be concluded that power in microwatts range can be typically harvested from these civil structures through directly bonded piezo patches in d31 mode. However, there are still issues associated with electronic circuitry accompanying harvesters, such as diodes and storage elements. The same are summarised and future directions envisioned.

A traceable dynamic calibration research of the measurement system based on quasi-static and dynamic calibration for accurate blast overpressure measurement

To ensure measurement accuracy in blast tests, the blast overpressure measurement system with piezoelectric sensors needs to be calibrated. Due to the charge leakage on the piezoelectric crystal and the decrease in the service life of the piezoelectric sensor under static pressure loads, the static calibration is not suitable here. This paper presents a traceable dynamic calibration method combining the quasi-static calibration using a drop-weight device and the dynamic calibration using a shock tube. First, the normalized low-frequency and high-frequency characteristics of the measurement system can be derived by the quasi-static calibration and the dynamic calibration, respectively. Then, based on the quasi-static calibration, a calculation method is proposed to obtain the performance characteristics which can be traceable to the SI, including the sensitivity, the linearity and the repeatability of the measurement system. Therefore, this calibration method combining quasi-static and dynamic calibration can help to obtain the frequency characteristics and the performance characteristics of the measurement system with traceability. For accurate blast overpressure measurement, based on the frequency characteristics derived from the calibration, the dynamic modelling and compensation are implemented on the measurement system to make the compensated measurement system meet the so-called undistorted measurement requirements. As the measurement system is compensated, it can be proved that the performance characteristics calculated by the quasi-static calibration are consistent with that of the compensated measurement system. So, the blast overpressure can be accurately represented with the multiplication of the calculated sensitivity traceable to the SI and the output voltage of the measurement system in blast overpressure measurement. By combining the traceable dynamic calibration with dynamic modelling and compensation, the calibrated and compensated measurement system can realize accurate blast overpressure measurement. Finally, influence factors of the blast overpressure measurement uncertainty are analyzed and possible measures to further improve the measurement accuracy are illustrated.

Direct observation of shift and ballistic photovoltaic currents.

The quantum phenomenon of shift photovoltaic current was predicted decades ago, but this effect was never observed directly because shift and ballistic currents coexist. The atomic-scale relaxation time of shift, along with the absence of a photo-Hall behavior, has made decisive measurement of shift elusive. Here, we report a facile, direct-current, steady-state method for unambiguous determination of shift by means of the simultaneous measurements of linear and circular bulk photovoltaic currents under magnetic field, in a sillenite piezoelectric crystal. Comparison with theoretical predictions permits estimation of the signature length scale for shift. Remarkably, shift and ballistic photovoltaic currents under monochromatic illumination simultaneously flow in opposite directions. Disentangling the shift and ballistic contributions opens the way for quantitative, fundamental insight into and practical understanding of these radically different photovoltaic current mechanisms and their relationship.

Nonlinear analysis of viscoelastic micro-composite beam with geometrical imperfection using FEM: MSGT electro-magneto-elastic bending, buckling and vibration solutions

In this research, the nonlinear static, buckling and vibration analysis of viscoelastic micro-composite beam reinforced by various distributions of boron nitrid nanotube (BNNT) with initial geometrical imperfection by modified strain gradient theory (MSGT) using finite element method (FEM) are presented. The various distributions of BNNT are considered as UD, FG-V and FG-X and also, the extended rule of mixture is used to estimate the properties of micro-composite beam. The components of stress are dependent to mechanical, electrical and thermal terms and calculated using piezoelasticity theory. Then, the kinematic equations of micro-composite beam using the displacement fields are obtained. The governing equations of motion are derived using energy method and Hamilton\'s principle based on MSGT. Then, using FEM, these equations are solved. Finally the effects of different parameters such as initial geometrical imperfection, various distributions of nanotube, damping coefficient, piezoelectric constant, slenderness ratio, Winkler spring constant, Pasternak shear constant, various boundary conditions and three material length scale parameters on the behavior of nonlinear static, buckling and vibration of micro-composite beam are investigated. The results indicate that with an increase in the geometrical imperfection parameter, the stiffness of micro-composite beam increases and thus the non-dimensional nonlinear frequency of the micro structure reduces gradually.

Defect states and vibration energy recovery of novel two-dimensional piezoelectric phononic crystal plate

The band structure and transmission characteristics of a new two-dimensional (2D) piezoelectric phononic crystal plate consisting of four epoxy short plates periodically connected with a square lattice of a prismatic piezoelectric material coated with plexiglass are investigated by supercell method and finite element method. By changing the electric boundary conditions imposed on the upper and lower surfaces of piezoelectric scatterers, a point defect waveguide with adjustable paths is formed, which overcomes the limitation of immutability in the direction of the vibration waveguide, with material and structural parameters fixed. Then the controlling of the piezoelectric effect can change the material parameters of piezoelectric components in phononic crystals, showing that the piezoelectric constants have a great influence on the complete bandgap, which is beneficial to the formation of defect states; when the frequency of the defect state appears in the band gap, the frequency-responding range of the defect state expands. The analysis of the displacement vector field indicates that the strain energy in the resonance of the new structure is almost completely limited to the upper and lower surfaces of the central piezoelectric scatterer. We use the recycling circuit to connect the electrodes on the upper and lower surfaces of the piezoelectric sheet. At this time, the output electrical energy can supply the power to the DC load, and the mechanical energy of vibration can be converted into electrical energy. The results of this work provide a reference for the self-powered technology of waveguide and wireless sensor device with adjustable path.