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Showing papers on "Piezoelectricity published in 2003"


Journal ArticleDOI
TL;DR: It is shown that when the ferroelectric layer is patterned into discrete islands using a focused ion beam, the clamping effect is significantly reduced, thereby facilitating the movement of ferroelastic walls.
Abstract: Dynamics of domain interfaces in a broad range of functional thin-film materials is an area of great current interest. In ferroelectric thin films, a significantly enhanced piezoelectric response should be observed if non-180° domain walls were to switch under electric field excitation. However, in continuous thin films they are clamped by the substrate, and therefore their contribution to the piezoelectric response is limited. In this paper we show that when the ferroelectric layer is patterned into discrete islands using a focused ion beam, the clamping effect is significantly reduced, thereby facilitating the movement of ferroelastic walls. Piezo-response scanning force microscopy images of such islands in PbZr0.2Ti0.8O3 thin films clearly point out that the 90° domain walls can move. Capacitors 1 μm2 show a doubling of the remanent polarization at voltages higher than ∼15 V, associated with 90° domain switching, coupled with a d33 piezoelectric coefficient of ∼250 pm V−1 at remanence, which is approximately three times the predicted value of 87 pm V−1 for a single domain single crystal.

515 citations


Journal ArticleDOI
TL;DR: In this paper, a lead-free piezoelectric ceramic ternary system based on bismuth sodium titanate, (Bi1/2Na 1/2)TiO3 (BNT)-bismuth potassium titanate (BKT) - barium titanate BaTiO 3 (BT) near the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral phases has been investigated.
Abstract: A lead-free piezoelectric ceramic ternary system based on bismuth sodium titanate, (Bi1/2Na1/2)TiO3 (BNT) - bismuth potassium titanate (Bi1/2K1/2)TiO3 (BKT) - barium titanate BaTiO3 (BT) near the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral phases has been investigated. In the case of a(Bi1/2Na1/2)TiO3–bBaTiO3–c(Bi1/2K1/2)TiO3 [BNBK(100a/100b/100c)] solid solution ceramics, the highest piezoelectric constant d33=191 pC/N, Curie temperature, Tc=301°C, electromechanical coupling factor, k33=0.56 and dielectric constant, e33T/e0=1141 are observed for the BNBK(85.2/2.8/12) composition which has a tetragonal phase near the MPB. The d33 value is the highest so far reported for all lead-free piezoelectric ceramics with Tc>300°C. The BNT-BKT-BT ternary ceramics system sintered at 1200°C for 2 h in air has a pure perovskite structure and a high density more than 95% of the theoretical density.

399 citations


Journal ArticleDOI
TL;DR: The theory and data for magnetoelectric (ME) coupling at electromechanical resonance (EMR) in the layered samples were investigated in this article, and the results showed that the ME voltage coefficient at resonance increases by a factor of 40 compared to low frequency values.
Abstract: Magnetoelectric interactions in bilayers of magnetostrictive and piezoelectric phases are mediated by mechanical deformation. This work is concerned with the theory and companion data for magnetoelectric (ME) coupling at electromechanical resonance (EMR) in the layered samples. Estimated ME voltage coefficient versus frequency profiles for nickel, cobalt, or lithium ferrite and lead zirconate titanate (PZT) predict a giant ME effect at EMR with the highest coupling expected for cobalt ferrite-PZT. There is excellent agreement between the theory and data for layered nickel ferrite-PZT; the ME voltage coefficient at resonance increases by a factor of 40 compared to low frequency values. Similar measurements on layered ferromagnetic alloy-PZT and bulk ferrite-PZT reveal even a stronger EMR assisted enhancement in ME coupling.

398 citations


Journal ArticleDOI
TL;DR: A novel, long-type of magnetostrictive and piezoelectric laminate composite design in which the layers are, respectively, magnetized/poled along their length axes, and a theory for modeling its behavior is presented.
Abstract: This paper presents a novel, long-type of magnetostrictive and piezoelectric laminate composite design in which the layers are, respectively, magnetized/poled along their length axes, and a theory for modeling its behavior. Using piezoelectric and magnetostrictive constitutive equations, and an equation of motion, a magneto-elasto-electric bieffect equivalent circuit is developed. The circuit is used to predict the longitudinal and transverse magnetoelectric (ME) voltage coefficients of our Terfenol-D/Pb(Zr/sub 1-x/Ti/sub x/)O/sub 3/ laminate design. It is found that the longitudinal ME voltage coefficient is significantly higher (/spl sim/5x) than the transverse one, and that our new laminate design has significantly higher ME voltage coefficients under small applied direct current (DC) magnetic bias fields than designs reported previously by other groups. Experimental values were found to be coincidental with predicted ones.

305 citations


01 Jan 2003
TL;DR: An overview of the literature on piezoelectric shunt damping is presented and recent observations on the feedback nature of piez ZoelectricShunt dampers are discussed, as a means of extracting mechanical energy from the base structure.
Abstract: Research on shunted piezoelectric transducers, per- formed mainly over the past decade, has generated new opportuni- ties for control of vibration and damping in flexible structures. This is made possible by the strong electromechanical coupling associ- ated with modern piezoelectric transducers. In vibration control applications, a piezoelectric transducer is bonded to, or embedded in a base structure. As the structure deforms, the piezoelectric el- ement strains and converts a portion of the structural vibration energy into electrical energy. By shunting the piezoelectric trans- ducer to an electrical impedance, a part of the induced electrical energy can be dissipated. Hence, the impedance acts as a means of extracting mechanical energy from the base structure. This paper reviews recent research related to the use of shunted piezoelec- tric elements for vibration damping and control. In particular, the paper presents an overview of the literature on piezoelectric shunt damping and discusses recent observations on the feedback nature of piezoelectric shunt damping systems.

299 citations


Journal ArticleDOI
TL;DR: In this paper, an exact three-dimensional analysis for a functionally gradient piezoelectric material rectangular plate that is simply supported and grounded along its four edges is presented, assuming that the mechanical and electric properties of the material have the same exponent-law dependence on the thickness coordinate.

240 citations


Journal ArticleDOI
TL;DR: In this article, the transverse piezoelectric properties of Pb(Zr, Ti)O 3 (PZT) films were estimated using a simple measuring method.
Abstract: Transverse piezoelectric properties of Pb(Zr, Ti)O 3 (PZT) films were estimated using a simple measuring method we developed. The c -axis oriented PZT films were epitaxially grown on Pt/MgO substrates, while the polycrystalline PZT films with the preferential orientation of 〈1 1 1〉 were deposited on Pt/Ti/Si substrates using rf sputtering technique. The piezoelectric characteristics of the PZT films with different crystalline structures were evaluated by the tip deflection of the unimorph cantilevers of the strip specimen just cleaved out from the substrates. The PZT films on MgO substrates showed excellent linear piezoelectric deflection to the applied voltage with the stable piezoelectric coefficient e 31 of −4.7 to −4.9 C/m 2 which is caused by the ideal lattice motion of the single domain structure. On the other hand, the PZT films on Si substrates showed large hysteresis of the deflection and the value of e 31 ranged from −4.3 to −7.5 C/m 2 according to the applied voltage. The non-linear as well as large piezoelectric response of the PZT films on Si is similar to conventional bulk PZT ceramics, indicating that the reorientation of domains whose polar axes are not parallel to the electric field is superimposed on the lattice motion.

208 citations


Journal ArticleDOI
TL;DR: In this paper, the spontaneous polarization and piezoelectric properties of boron nitride nanotubes were analyzed and it was shown that they are excellent picolectric systems with response values larger than those of polymers.
Abstract: Ab initio calculations of the spontaneous polarization and piezoelectric properties of boron nitride nanotubes show that they are excellent piezoelectric systems with response values larger than those of piezoelectric polymers. The intrinsic chiral symmetry of the nanotubes induces an exact cancellation of the total spontaneous polarization in ideal, isolated nanotubes of arbitrary indices. Breaking of this symmetry by intertube interaction or elastic deformations induces spontaneous polarization comparable to those of wurtzite semiconductors.

200 citations


Journal ArticleDOI
TL;DR: In this paper, the complete piezoelectric tensors of both the wurtzite and zinc blende polymorphs of ZnO and ZnS have been computed by ab initio periodic linear combination of atomic orbitals (LCAO) methods, based mainly on the Hartree-Fock Hamiltonian, with an all-electron Gaussian-type basis set.

195 citations


Journal ArticleDOI
TL;DR: In this article, perovskite ferroelectric single crystals in the (1−x)BiScO3-xPbTiO3 (BSPT) system were grown using a flux method.
Abstract: Perovskite ferroelectric single crystals in the (1−x)BiScO3-xPbTiO3 (BSPT) system were grown using a flux method. The Curie temperature of rhombohedral BSPT(43/57) crystals was found to be about 404 °C, with a rhombohedral–tetragonal phase transition temperature (Tr−t) around 350 °C. The coercive field (Ec) was found to be 13.7 kV/cm for 〈001〉-oriented crystals, while the coupling factor k33 was determined to be ∼90% at room temperature and was nearly temperature independent until 330 °C. High piezoelectric properties together with a high Curie temperature and coercive field make rhombohedral BSPT crystals promising candidates for the next generation of high-performance, high-temperature actuators and transducers.

176 citations


Journal ArticleDOI
TL;DR: The piezoelectric, dielectric and ferroelectric properties of lead zirconate titanate (PZT) films have been investigated as a function of Zr/Ti ratio.
Abstract: The piezoelectric, dielectric, and ferroelectric properties of highly (111)-textured, 200-nm-thick polycrystalline lead zirconate titanate (PZT) films have been investigated as a function of Zr/Ti ratio. The distinct peak in piezoelectric coefficient at the morphotropic phase boundary found in bulk PZT ceramics is not observed in thin film PZTs. Measurements of the temperature dependence of relative permittivity and the nonlinear behavior of relative permittivity and piezoelectric coefficient suggest that non-180° domain wall motion in these films is negligible, indicating that the extrinsic contribution to the room temperature permittivity is dominated by only 180° domain wall motion. The semiempirical phenomenological equation relating the piezoelectric coefficient to measured polarization and permittivity values is demonstrated to give an excellent description of the piezoelectric behavior in these films, assuming bulk electrostrictive and elastic coefficients. The small deviation between calculated and measured piezoelectric coefficients as well as the dependence of piezoelectric and polarization behavior on the external field, i.e., hysteresis loop, are suggested to be primarily due to backswitching of 180° domains.

Journal ArticleDOI
TL;DR: The feasibility of transmitting electric energy through a metal wall by propagating acoustic waves using piezoelectric transducers is examined by studying the efficiency of power transmission and its dependence upon the relevant system parameters for a simplified system consisting of an elastic plate sandwiched by two piez Zoelectric layers.
Abstract: The feasibility of transmitting electric energy through a metal wall by propagating acoustic waves using piezoelectric transducers is examined by studying the efficiency of power transmission and its dependence upon the relevant system parameters for a simplified system consisting of an elastic plate sandwiched by two piezoelectric layers. One of these layers models the driving transducer for generating acoustic wave, and the other layer models the receiving transducer for converting the acoustic energy into electric energy to power a load circuit. The output voltage, the output power, and the efficiency of this system are expressed as explicit functions of the system parameters. A numerical example is included to illustrate the dependence of the system performance upon the physical and geometrical parameters.

Journal ArticleDOI
TL;DR: In this paper, a beam-shaped PZT actuator sample with a graded porosity content across its thickness was fabricated by sintering PFA-graded powder compacts.
Abstract: Porous ceramics of lead zirconate titanate (PZT) were prepared by sintering powder compacts consisting of PZT and stearic acid powders in an air atmosphere; stearic acid was added as a pore-forming agent (PFA). The dielectric, elastic and piezoelectric properties of uniformly porous PZT ceramics were investigated as a function of the porosity volume fraction. Furthermore, a beam-shaped PZT actuator sample with a graded porosity content across its thickness was fabricated by sintering PFA-graded powder compacts. The electric-field-induced bending displacement characteristics of the actuator samples were measured by using strain gauges and were found to be in good agreement with the theoretical predication based on a classical lamination theory.

Journal ArticleDOI
TL;DR: In this article, the orientation dependence of the longitudinal piezoelectric coefficient, d(33)(*), is investigated as a function of temperature in BaTiO3 and PbTiO2 crystals using the Landau-Ginsburg-Devonshire theory.
Abstract: The orientation dependence of the longitudinal piezoelectric coefficient, d(33)(*), is investigated as a function of temperature in BaTiO3 and PbTiO3 crystals using the Landau-Ginsburg-Devonshire theory. We show that a presence of the ferroelectric-ferroelectric phase transitions in BaTiO3 leads to enhanced d(33)(*) along nonpolar directions. The reason for this is that in the vicinity of a phase transition temperature at which a polarization vector changes its direction (tetragonal-orthorhombic/monoclinic, orthorhombic/monoclinic-rhombohedral), the shear piezoelectric coefficients become high. It is shown for all ferroelectric phases of BaTiO3 that the shear stress deforms the crystal cell and changes the polarization direction in a similar way as the corresponding temperature-induced phase transition. The influence of the piezoelectric shear effect on the anisotropy of d(33)(*) is particularly pronounced in the orthorhombic/monoclinic phase where the piezoelectric shear coefficients are determined by the presence of both the high-temperature tetragonal and the low-temperature rhombohedral phases. In PbTiO3, which does not exhibit ferroelectric-ferroelectric phase transitions, the shear piezoelectric effect is weak and d(33)(*) has its maximum along the polar axis at all temperatures. These results can be generalized to include phase transitions induced by electric-field and composition variations and are valid for all perovskite materials, including complex relaxor-ferroelectric perovskites that have recently attracted attention for their exceptionally large piezoelectric properties. (C) 2003 American Institute of Physics.

Journal ArticleDOI
TL;DR: In this paper, the PZT/Pt composites with various compositions were fabricated by using powder processing, and their mechanical, dielectric, piezoelectric and elastic properties were evaluated with the purpose to develop actuators with functionally graded microstructure (FGM).
Abstract: The PZT/Pt composites with various compositions were fabricated by using powder processing, and their mechanical, dielectric, piezoelectric and elastic properties were evaluated with the purpose to develop piezoelectric actuators with functionally graded microstructure (FGM). The piezoelectric and dielectric constants of the PZT/Pt composites decreased monotonously with increasing Pt content, whereas the addition of the Pt particles greatly improved the mechanical properties, particularly the fracture toughness in the composites. Miniature bimorph-type FGM actuators that consist of a composite internal-electrode (70 vol.%PZT/30 vol.%Pt) and three piezoelectric layers (100 vol.%PZT to 80 vol.%PZT/20 vol.%Pt) were fabricated by powder stacking and normal sintering techniques. The electrically-induced deflection characteristics of such an FGM actuator were measured with electric strain gages mounted on the top and bottom surfaces of the actuators, and the measured data were consistent with the analytical results given by the modified classical lamination theory model (CLT).

Journal ArticleDOI
TL;DR: In this paper, a combination of modeling and experimental work has led to the identification of a crystal cut of PZN-4.5%PT with enhanced piezoelectric coefficients for bending mode applications.

Patent
25 Mar 2003
TL;DR: In this article, a surface acoustic wave device (e.g., filter or convolver) is designed to increase an electromechanical coupling factor K2 and is basically configured by a substrate, a buffer layer, a piezoelectric layer and an electrode layer.
Abstract: A surface acoustic wave device (e.g., filter or convolver) is designed to increase an electromechanical coupling factor K2 and is basically configured by a substrate, a buffer layer, a piezoelectric layer and an electrode layer. Herein, the substrate is made of a bulk material (e.g., SrTiO3), which allows growth of a perovskite compound crystal being expressed by a general chemical formula of SrZO3 (where Z denotes an element such as Zr and Sn whose valence is 4). The buffer layer is formed on the substrate and is made of the perovskite compound crystal (e.g., SrZrO3, SrSnO3), which has good lattice matching with KNbO3. The piezoelectric layer is made of a KNbO3 single crystal and is formed on the buffer layer with a thickness of 500 nm or so. The electrode layer is formed on or below the piezoelectric layer. An interdigital transducer consisting of input and output electrodes is formed by patterning using photolithography technique being effected on the electrode layer, which is made of a metal material (e.g., Al). In addition, it is possible to form a temperature stabilization layer between the piezoelectric layer and electrode layer. The temperature stabilization layer is made of a material (SiO2) having a temperature coefficient reverse to a temperature coefficient of the piezoelectric layer so as to ease distortion being caused to occur due to differences in thermal expansion between the piezoelectric layer and electrode layer. Incidentally, the temperature stabilization layer has a prescribed thickness, which is approximately 1000 nm.

Journal ArticleDOI
TL;DR: In this article, the cylindrical bending of multilayered, linear, and anisotropic magneto-electro-elastic plates under simple-supported edge conditions is studied.

Proceedings ArticleDOI
25 Jul 2003
TL;DR: In this article, two types of piezoelectric materials were experimentally investigated for use as power harvesting devices, i.e., monolithic PZT and Macro Fiber Composites, which were recently developed at the NASA Langley Center.
Abstract: Piezoelectric materials can be used as mechanisms to transfer ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, Piezoelectric power generation can provide a conventional alternative to traditional power sources used to operate certain types of sensors/actuators, telemetry, and MEMS devices. In this paper, two types of piezoelectric materials were experimentally investigated for use as power harvesting devices. The two types being the commonly used monolithic piezoelectric (PZT) and Macro Fiber Composites (MFC), which were recently developed at the NASA Langley Center. Our experimental results estimate the efficiency of these devices and identify the feasibility of their use in real world applications. In general the power produced by the vibration of a piezoelectric device is on the order of a few milliwatts which is far too little to power for most applications. Therefore, each the transducer is used to charge nickel metal hydride batteries of varying sizes to compare their performance and ability of to store electrical power. The results presented in this paper show the potential of piezoelectric materials for use in power harvesting applications.

Journal ArticleDOI
TL;DR: In this article, a magnetoelectric (ME) hybrid structure is constructed by an efficient coupling between magnetostrictive Terfenol-D (Tb0.27-0.30Dy0.95)/epoxy composites.
Abstract: A magnetoelectric (ME) hybrid structure is constructed by an efficient coupling between magnetostrictive Terfenol-D (Tb0.27-0.30Dy0.73-0.70Fe1.90-1.95)/epoxy and piezoelectric lead–zirconate–titanate [Pb(Zr0.52Ti0.48)O3]/epoxy composites. Significant ME effect produced by the piezoelectric k31 coupling with the longitudinal vibration of the magnetostrictive component over a wide range of frequency is observed. It is revealed that the ME effect can be enhanced by applying an optimized magnetic bias. A magnetoelectric voltage coefficient as high as 8700 mV/cm Oe is recorded at the resonance frequency of 59.2 kHz for the structure with an optimized magnetic bias of 0.7 kOe. Our measurement confirms that the eddy current loss remains negligibly small at an operating frequency as high as ∼200 kHz, predicting very promising applications of the present ME structure.

Journal ArticleDOI
TL;DR: In this paper, the authors combine ab initio, tight-binding methods and analytical theory to study the piezoelectric effect of boron nitride nanotubes.
Abstract: We combine ab initio, tight-binding methods and analytical theory to study piezoelectric effect of boron nitride nanotubes. We find that piezoelectricity of a heteropolar nanotube depends on its chirality and diameter andcan be understood starting from the piezoelectric response of an isolated planar sheet, along with a structure specific mapping from the sheet onto the tube surface. We demonstrate that a linear coupling between the uniaxial and shear deformation occurs for chiral nanotubes. Our study shows that piezoelectricity of nanotubes is fundamentally different from its counterpart in three-dimensional bulk materials.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the electromechanical response of piezoelectric ceramics as a function of the amplitude and frequency of large electric fields and studied the effects of dc bias fields.
Abstract: We have investigated the electromechanical response of piezoelectric ceramics as a function of the amplitude and frequency of large electric fields and studied the effects of dc bias fields In order to characterize the materials under these conditions, a ZMI 2000 laser interferometer system from Zygo Corp has been installed and modified to directly measure the strains of ferroelectric ceramics This system uses a heterodyne detection technique and has the advantages of phase detection, wide bandwidth, high stability, and easy optical alignment Our experiment has been used to determine the strain of lead zirconate titanate (PZT) ceramics as a function of electric fields and as a function of frequency in the low frequency range From these measurements the piezoelectric coefficients d33, d31, and d15 have been determined as a function of applied field and frequency In addition the dependence of the piezoelectric coefficients under an applied dc bias field has been studied under quasistatic and under res

Journal ArticleDOI
TL;DR: A laser scanning vibrometer (LSV) was used for the first time to measure the piezoelectric coefficient of ferroelectric thin films based on the converse piezOElectric effect.
Abstract: A laser scanning vibrometer (LSV) was used for the first time to measure the piezoelectric coefficient of ferroelectric thin films based on the converse piezoelectric effect. The significant advantages of the use of the LSV or this purpose were demonstrated. Several key points were discussed in order to achieve reliable and accurate results.

Journal ArticleDOI
TL;DR: In this paper, the theoretical foundations of piezoelectric resonance, examines the experimental aspects, and reviews recent applications in the field of polymers. But the authors do not discuss the application of this technique in actuator applications.
Abstract: Piezoelectric polymers are widely used in sensor and actuator applications. Compared to ceramic materials, they have the advantage of mechanical flexibility and an acoustic impedance similar to those of water or air. Their electrical, electromechanical and mechanical properties can be investigated by analyzing piezoelectric resonances in their dielectric spectrum. Apart from its ability to reveal the high-frequency behavior of piezoelectric polymer films, this technique is appealing from a practical point of view because several important parameters can be measured with a single scan that only requires standard dielectric spectroscopy equipment commonly found in many laboratories. This article outlines the theoretical foundations of piezoelectric resonance, examines the experimental aspects, and reviews recent applications in the field of piezoelectric polymers.

Patent
09 Sep 2003
TL;DR: In this paper, the size of an aperture defined by selected irradiating piezoelectric elements may be determined based on a focal distance of an ultrasonic wave focusing is performed by varying delay times of drive signals applied to the selected piezel elements.
Abstract: An ultrasound irradiation apparatus which irradiates an ultrasonic wave to a desired area by selecting two or more piezoelectric elements and by changing the selected piezoelectric elements. The selection may be performed by mechanical movement of substrates or electrical switches. A size of an aperture defined by selected irradiating piezoelectric elements may be determined based on a focal distance of an ultrasonic wave focusing is performed by varying delay times of drive signals applied to the selected piezoelectric elements.

Journal ArticleDOI
TL;DR: In this paper, it is shown that the shear deformations of polymers are characterized by a strong piezoelectric response, which is made by the size effect and electrostriction, which are related to each other.
Abstract: The piezoelectricity observed in poly(vinylidene fluoride) (PVDF) and its copolymers involves three components that are associated with the presence of at least two phases (crystalline and amorphous) in the polymer structure. The main contributions to the phenomenon observed are made by the size effect and electrostriction, which are related to each other. These contributions manifest themselves through the mechanism of strain-induced reversible transformations of a number of domains of the anisotropic amorphous phase into the crystalline state under the action of mechanical or electrical fields. With due regard for different packings of chains in the amorphous and crystalline phases, this mechanism accounts for the large Poisson ratios μ31 obtained for textured films of flexible-chain crystallizing polymers. The dependence of the piezoelectric coefficient d 32 on the static stress in textured films is governed by the change in the fraction of the crystalline phase due to strong anisotropy of the elastic constants in the film plane. It is shown that the shear deformations of polymers are characterized by a strong piezoelectric response. The specific features revealed in the piezoelectric effect under bending deformations are described for films with an inhomogeneous distribution of polarization over the cross section. The general regularities of the electrostriction in the polymers and inorganic relaxor ferroelectrics studied are considered.

Patent
15 Jan 2003
TL;DR: In this paper, a system for generating electric power from a rotating tire's mechanical energy concerns a power generation device with a piezoelectric structure and an energy storage device.
Abstract: A system for generating electric power from a rotating tire's mechanical energy concerns a power generation device with a piezoelectric structure and an energy storage device. The piezoelectric structure preferably comprises a plurality of piezoelectric fibers embedded in a generally unidirectional fashion within an epoxy matrix. The piezoelectric structure may be mounted on a support substrate that helps distribute mechanical strain to which the piezoelectric fibers are subjected in a substantially uniform fashion. The piezoelectric structure is preferably mounted within a tire structure such that electric charge is generated therein as the wheel assembly moves along a ground surface. Electrode layers within the piezoelectric structure are coupled to a power conditioning module that rectifies the resultant electric current from the piezoelectric structure and stores it in an energy storage device, preferably an electrolytic capacitor. A rechargeable battery may also be provided for storing additional charge generated within the piezoelectric structure. A regulated voltage source is provided from the energy stored in the power generation device and can be used to power various electronics systems integrated within a tire or wheel assembly. An example of an integrated tire electronics system for use with the disclosed power generation device corresponds to a tire monitoring system that wirelessly transmits such information as tire pressure, temperature and identification variables to a remote receiver location.

Journal ArticleDOI
TL;DR: In this article, the authors synthesize dense KNbO3 ceramics by pressureless sintering under optimized heat-treatment conditions using a small amount of La2O3 and FeO3 additives.
Abstract: Dense KNbO3 ceramics have been successfully synthesized by pressure-less sintering under optimized heat-treatment conditions using a small amount of La2O3 and Fe2O3 additives KNbO3 forms (K1-xLax)(Nb1-xFex)O3 solid solutions and changes in the crystal system, depending on the additive content, from orthorhombic to tetragonal at x of 0020, and from tetragonal to cubic at x of 0200 or higher When only 0002 mol of La2O3 and Fe2O3 (x=0002) was added into KNbO3, the highest value (988%) of the theoretical density was obtained This specimen showed orthorhombic symmetry with a high Curie temperature of 420°C, and demonstrated a well-saturated ferroelectric hysteresis loop with large remanent polarization (Pr) of 18 µC/cm2, which is comparable to the value reported for pure KNbO3 ceramics fabricated by hot pressing Furthermore, the x=0002 specimen showed a planar electromechanical coupling ratio (kp) of 017 and piezoelectric d33 constant of 98 pC/N, regardless of the unsaturated poling state

Journal ArticleDOI
TL;DR: In this paper, a differential pressure liquid flow sensor has been fabricated on a polyimide membrane and a test device has been tested with a piezoelectric micropump for flow rates from 30 µl h−1 to 300 µl H−1.
Abstract: Fabrication and characterization of ZnO thin film piezoelectric sensors on a polyimide membrane is presented in this paper. As a test device a differential pressure liquid flow sensor has been fabricated. We discuss new material combinations for the fabrication of the test devices. The pressure sensor membrane is a thin polyimide sheet bonded to a silicon wafer and the sensing material is sputtered ZnO piezoelectric thin film. The fabricated liquid flow sensor has been tested with a piezoelectric micropump for flow rates from 30 µl h−1 to 300 µl h−1. Stroke volumes of 1 to 10 nl have been measured. The strain in the sensing layer has been modeled and a transverse piezoelectric coefficient of e31,f = −0.294 C m−2 has been extracted.

Journal ArticleDOI
TL;DR: A piezoelectric microelectromechanical switch actuated by lead zirconate titanate (PZT) is reported in this article, where the PZT thin film was poled and driven with interdigitated electrodes to exploit the d33 coefficient.
Abstract: A piezoelectric microelectromechanical switch actuated by lead zirconate titanate (PZT) is reported. A PZT unimorph cantilever actuator, fabricated on a sacrificial polysilicon layer and released using a xenon difluoride dry etch, was used to realize the switch. The PZT thin film was poled and driven with interdigitated electrodes to exploit the d33 coefficient for switching actuation. Preliminary dc and rf switching characteristics are reported. Measurements indicate a fast switching “on” time of 25 dB was achieved up to 100 MHz.