Showing papers on "Lead zirconate titanate published in 2003"
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
TL;DR: In this paper, the effective transverse piezoelectric coefficient e(31,f) of sol-gel processed films was investigated as a function of composition, film texture and film thickness.
Abstract: Pb(Zr-x, Ti1-x)O-3 (PZT) piezoelectric thin films are of major interest in MEMS technology for their ability to provide electro-mechanical coupling. In this work, the effective transverse piezoelectric coefficient e(31,f) of sol-gel processed films was investigated as a function of composition, film texture and film thickness. Dense, textured and crack-free PZT films have been obtained on silicon substrates up to a thickness of 4 mum. Crystallization anneals have been performed for every 0.25 mum. Nucleation on the previous perovskite layer combined with directional growth leads to a gradient of the compositional parameter x of +/-20% (at x = 0.53 average composition). Best properties have been achieved with {100}-textured film of x = 0.53 composition. Large remanent e(31,f) values of -11 to -12 C/m(2) have been obtained in the whole thickness range of 1-4 mum. These values are superior to values of undoped bulk ceramics, but smaller than in current, optimized (doped) bulk PZT. (C) 2003 Elsevier Science B.V. All rights reserved.
370 citations
TL;DR: In this article, strong magnetoelectric coupling was observed in zinc-substituted layered composites of ferrites and lead zirconate titanate (PZT).
Abstract: The observation of strong magnetoelectric (ME) coupling is reported in zinc-substituted layered composites of ferrites and lead zirconate titanate (PZT). Multilayer samples contained cobalt zinc ferrite ${\mathrm{Co}}_{1\ensuremath{-}x}{\mathrm{Zn}}_{x}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ (CZFO) $(x=0--0.6)$ or nickel zinc ferrite ${\mathrm{Ni}}_{1\ensuremath{-}x}{\mathrm{Zn}}_{x}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ (NZFO) $(x=0--0.5)$ and were prepared by laminating and sintering ferrite and PZT thick films obtained by tape casting. The ME voltage coefficient ${\ensuremath{\alpha}}_{E}$ was measured for transverse and longitudinal field orientations for frequencies 10--1000 Hz. A substantial enhancement in ${\ensuremath{\alpha}}_{E}$ is observed with the substitution of Zn. The largest increase, by about 500%, is observed in CZFO-PZT and the smallest increase of 60% is measured for NZFO-PZT. As the Zn concentration is increased, ${\ensuremath{\alpha}}_{E}$ increases and shows a maximum for $x=0.2--0.4,$ depending on the ferrite. The data is analyzed based on a theoretical model for a ferrite-PZT bilayer, taking into consideration less than ideal coupling at the interface. The interface coupling parameter k is quite small for CZFO-PZT; it increases from 0 to 0.6 as Zn concentration is increased from 0% to 40%. Composites of NZFO-PZT, however, have a near perfect interface coupling. The Zn-assisted enhancement in the ME coefficient is discussed in terms of joule magnetostriction, initial permeability, and magnetomechanical coupling for the ferrites.
304 citations
TL;DR: In this article, the fabrication of ferroelectric oxide nanoshell tubes as well as ordered nanotube arrays have been accomplished using a simple and convenient fabrication method that allows full tailoring of tube dimensions and array pattern and size.
Abstract: Wafer-scale fabrication of ferroelectric oxide nanoshell tubes as well as ordered nanotube arrays have been accomplished using a simple and convenient fabrication method that allows full tailoring of tube dimensions as well as array pattern and size. Using different silicon and alumina templates, barium titanate and lead zirconate titanate tubes with diameters ranging from 50 nm up to several micrometers meter and lengths of more 100 μm have been fabricated. Ferroelectric switching of submicrometer tubes has been shown using piezoresponse scanning probe microscopy.
283 citations
TL;DR: In this article, the authors investigated the effect of strain gradient on flexoelectricity in unpoled soft lead zirconate titanate (PZT) ceramic.
Abstract: Strain-gradient-induced polarization or flexoelectricity was investigated in unpoled soft lead zirconate titanate (PZT) ceramic where the texture symmetry ∞∞m forbids macropiezoelectricity. Even under high strain gradient (1 m−1) the induced polarization is small (1.6 μC/m2) at 20 °C. Higher strain gradients induce ferroelastic poling and an additional extrinsic contribution to the flexoelectric coefficient μ12 raising the value from 0.5 to 2.0 μC/m. Cooling through the Curie point (TC) under maximum stress (80 MPa) where the peak permittivity (∼20 000) could raise μ12 to 20 μC/m, the equivalent electric field is still only ∼1 kV/m, inadequate to achieve significant ferroelectric poling. The situation may be different in thin PZT films where much larger strain gradients can occur.
255 citations
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.
173 citations
TL;DR: In this paper, a linear strain distribution is assumed across the thickness of the passive plate of the lead zirconate titanate (PZT) actuator given that the mechanical properties such as Young's modulus and Poisson ratio of the actuator and passive plate are close.
Abstract: Closed form analytical equations are important tools for predicting and optimizing the behavior of a piezoelectric microactuator for micropump applications. However, there is no reliable analytical solution to date to analyze the behavior of a circular piezoelectric microactuator for a valveless micropump. In this paper, a linear strain distribution is assumed across the thickness of the passive plate of the lead zirconate titanate (PZT) actuator given that the mechanical properties such as Young’s modulus and Poisson ratio of the actuator and the passive plate are close. An analytical equation for the passive plate deflection is derived upon this assumption. The analytical result shows excellent agreement with experimental data as well as the results from finite element simulation. Based on this analytical model, the effects of several important parameters and nondimensional variable groups on the actuator performance have been investigated. These parameters and variables include the dimensions and mechanical properties of the PZT disk, the passive plate, and the bonding layer material.
153 citations
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.
152 citations
TL;DR: In this paper, a self-patterning method making use of the instability of ultrathin films during high-temperature treatments was used to obtain lead zirconate titanate nanoislands.
Abstract: Lead zirconate titanate nanoislands were obtained by a self-patterning method making use of the instability of ultrathin films during high-temperature treatments. After high-temperature annealing, the as-deposited film breaks into islands with a narrow size distribution. The single-crystal nanoislands were studied by scanning and high-resolution transmission electron microscopy, atomic force microscopy, and x-ray diffraction. They show an epitaxial relationship with the Nb-doped (001) SrTiO3 substrate. The ferroelectric switching of several individual islands was investigated by piezoresponse force microscopy.
139 citations
TL;DR: In this paper, a microelectromechanical system (MEMS) accelerometer based on piezoelectric lead zirconate titanate (PZT) films with trampoline or annular diaphragm structures was designed, fabricated by bulk micromachining, and tested.
Abstract: Microelectromechanical systems (MEMS) accelerometers based on piezoelectric lead zirconate titanate (PZT) thick films with trampoline or annular diaphragm structures were designed, fabricated by bulk micromachining, and tested. The designs provide good sensitivity along one axis, with low transverse sensitivity and good temperature stability. The thick PZT films (1.5-7 /spl mu/m) were deposited from an acetylacetonate modified sol-gel solution, using multiple spin coating, pyrolysis, and crystallization steps. The resulting films show good dielectric and piezoelectric properties, with P/sub r/ values >20 /spl mu/C/cm/sup 2/, /spl epsiv//sub r/>800, tan/spl delta/ 6.5 C/m/sup 2/. The proof mass fabrication, as well as the accelerometer beam definition step, was accomplished via deep reactive ion etching (DRIE) of the Si substrate. Measured sensitivities range from 0.77 to 7.6 pC/g for resonant frequencies ranging from 35.3 to 3.7 kHz. These accelerometers are being incorporated into packages including application specific integration circuit (ASIC) electronics and an RF telemetry system to facilitate wireless monitoring of industrial equipment.
133 citations
TL;DR: A piezoelectric ultrasonic micromotor has been developed using a lead zirconate titanate (PZT) ceramic/metal composite tube stator that was 1.5 mm in diameter and 7 mm in length, which showed good reliability and stability for more than 300 hours of continued operation.
Abstract: A piezoelectric ultrasonic micromotor has been developed using a lead zirconate titanate (PZT) ceramic/metal composite tube stator that was 1.5 mm in diameter and 7 mm in length. The micromotor was operated in its first bending vibration mode (/spl sim/70 kHz), producing speeds from hundreds to over 2000 rpm in both rotational directions. The maximum torque-output was 45 /spl mu/N-m, which is far superior to previous PZT thin film-based micromotors. This micromotor showed good reliability and stability for more than 300 hours of continued operation.
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
TL;DR: In this article, the authors investigated piezoelectric lead zirconate titanate (PZT)-stainless steel cantilevers as real-time in-water cell detectors using yeast cells as a model system.
Abstract: We have investigated piezoelectric lead zirconate titanate (PZT)-stainless steel cantilevers as real-time in-water cell detectors using yeast cells as a model system. Earlier studies have shown that mass changes of a cantilever can be detected by monitoring the resonance frequency shift. In this study, two PZT-stainless steel cantilevers with different sensitivities were used to detect the presence of yeast cells in a suspension. The stainless steel cantilever tip was coated with poly-L-lysine that attracted yeast cells from the suspension, and immobilized them on the cantilever surface. After immersing the poly-L-lysine coated tip in a yeast suspension, the flexural resonance frequency of the cantilever was monitored with time. The flexural resonance frequency decreased with time in agreement with the optical micrographs that showed increasing amount of adsorbed yeast cells with time. The resonance frequency shifts are further shown to be consistent with both the mass of immobilized cells on the poly-L-l...
TL;DR: In this paper, the effects of Mn doping on the ferroelectric and pyroelectric properties of Pb(Zr0.3Ti0.7)O3 (PZT) thin films on substrates Pt/Ti/SiO2/Si.
Abstract: We have investigated the effects of Mn doping on the ferroelectric and pyroelectric properties of Pb(Zr0.3Ti0.7)O3 (PZT) thin films on substrates Pt/Ti/SiO2/Si. The Mn-doped (1 mol %) PZT (PMZT) showed almost no hysteretic fatigue up to 1010 switching bipolar pulse cycles, coupled with excellent retention properties. We present evidence that while a low permittivity interfacial layer forms between the Pt electrode and PZT films, this does not occur in PMZT. We propose that Mn dopants are able to reduce oxygen vacancy mobility in PZT films and Mn2+ ions consume the oxygen vacancies generated during repeated switching, forming Mn4+ ions. These mechanisms are probably responsible for their low observed fatigue characteristics. Mn doping brings additional benefits to the electrical properties of PZT films. The relevant pyroelectric coefficients (p) of a 700 nm thick film are 3.52×10−4 C m−2 K−1 and detectivity figures of merit FD=3.85×10−5 Pa−0.5 at 33 Hz for Mn-doped PZT, compared with p=2.11×10−4 C m−2 K−1 and FD=1.07×10−5 Pa−0.5 for the undoped PZT films. This means that the Mn-doped PZT thin films are excellent candidates as device materials for both memory and pyroelectric applications.
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.
Patent•
14 Feb 2003
TL;DR: In this article, a method for manufacturing FeRAM is provided with a process of depositing a PbTi layer 5 on a Pt layer 4 which forms a part of a lower electrode, an oxidizing process was used to oxidize the layer 5, and an upper electrode was placed on the PZT layer 6.
Abstract: PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device where ferroelectric substance characteristic can be improved by improving crystallinity of lead titanate lead zirconate titanate (PZT) SOLUTION: A method for manufacturing FeRAM is provided with a process of depositing a PbTi layer 5 on a Pt layer 4 which forms a part of a lower electrode, a process of oxidizing the deposited PbTi layer 5, a process of arranging a PZT layer 6 on the PbTi layer 5 which is oxidized and formed, and a process of arranging an upper electrode 7 on the PZT layer 6 All of the layers are deposited through sputtering method
TL;DR: In this paper, a PZT thin film on a low stress silicon nitride (Si x N y ) support buffered by a layer of ZrO 2 was fabricated using surface micromaching techniques.
Abstract: Piezoelectric Pb(Zr 0.52 Ti 0.48 )O 3 (PZT 52/48) cantilever actuators that operate in the d 33 mode were fabricated using surface micromaching techniques. The cantilevers are composed of a PZT thin film on a low stress silicon nitride (Si x N y ) support buffered by a layer of ZrO 2 . Au/Cr interdigitated (IDT) electrodes were deposited on the PZT film surface, so that the cantilever could be poled and actuated in the d 33 mode. The PZT deposited on the ZrO 2 /Si x N y /Si stack is well-crystallized into the perovskite phase and is randomly oriented. It exhibits good ferroelectric behavior with a remanent polarization of 26 μC/cm 2 . The cantilevers have a width of 100 μm and lengths between 130 and 280 μm. The fundamental resonance frequencies are in the range of 6.1–29.6 kHz. When actuated with an applied electric voltage of 100 V, the 280 μm long cantilever exhibits a large downward tip displacement of 30 μm.
TL;DR: In this paper, the authors used interdigitated (IDT) electrodes to exploit a combination of the d33 and d31 piezoelectric responses of lead zirconate titanate (PZT) thin films.
Abstract: Piezoelectric bulk micromachined accelerometers have been designed and fabricated using silicon micromachining techniques. These devices use interdigitated (IDT) electrodes to exploit a combination of the d33 and d31 piezoelectric responses of lead zirconate titanate (PZT) thin films. A simple fabrication process involving only three photomasks and two deep-trench reactive ion-etching (DRIE) steps has been developed. Frequency response measurement has been used to measure the sensitivity of the devices as well as the bandwidth. Voltage sensitivities in the range of 1.3–7.86 mV/g with corresponding resonance frequencies in the range of 23–12 kHz have been obtained for these accelerometers. The voltage sensitivity mode of the interdigitated electrode accelerometer results in a higher acceleration sensitivity than that for a through-the-thickness poled PZT accelerometers with identical device structure.
TL;DR: In this article, a flexible, free-standing piezo and pyroelectric composite with 0 to 3 connectivity was made up from Lead Zirconate Titanate (PZT) powder and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) copolymer.
Abstract: Flexible, free-standing piezo and pyroelectric composite with 0 to 3 connectivity was made up from Lead Zirconate Titanate (PZT) powder and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) copolymer. The pyroelectric and the piezoelectric longitudinal (d33) coefficients were measured. A 50/50 vol.% PZT/PVDF-HFP composite resulted in piezo and pyroelectric coefficients of d33 = 25.0 pC/N and p = 4.5 × 10-4 C/m²K at 70 °C, respectively. Analysis of the complex permittivity in a wide range of frequency was carried out indicating lower permittivity of the composite in comparison with a permittivity of the PZT ceramic. The low value of the permittivity gives a high pyroelectric figure of merit indicating that this material can be used to build a temperature sensor in spite of the lower pyroelectric coefficient compared with PZT.
TL;DR: In this article, a magnetoelectric (ME) composite of lead zirconate titanate (PZT) and Co-ferrite with various compositions was prepared by using conventional ceramic sintering process.
Abstract: Magnetoelectric (ME) composites of lead zirconate titanate (PZT) and Co-ferrite with various compositions were prepared by using conventional ceramic sintering process. The variation of dielectric behavior of the composites with frequency in the range of 100 Hz to 1 MHz at room temperature was studied. The ME coefficient was investigated at various bias fields and frequency. The maximum ME voltage coefficient (d E /d H ) was 30.2 mV (cm Oe) −1 for 0.8 PZT+0.2 Co-ferrite composite ceramic.
TL;DR: The measurements for some lead zirconate titanate (PZT) based ceramics are used as examples to demonstrate the calculation and experimental procedures and the comparisons with the standard methods.
Abstract: This paper presents a method of accurately determining the complex piezoelectric and elastic coefficients of piezoelectric ceramic resonators from the measurement of the normalized electric admittance, Y~, which is electric admittance Y of piezoelectric resonator normalized by the angular frequency /spl omega/. The coefficients are derived from the measurements near three special frequency points that correspond to the maximum and the minimum normalized susceptance (B~) and the maximum normalized conductance (G~). The complex elastic coefficient is determined from the frequencies at these points, and the real and imaginary parts of the piezoelectric coefficient are related to the derivative of the susceptance with respect to the frequency and the asymmetry of the conductance, respectively, near the maximum conductance point. The measurements for some lead zirconate titanate (PZT) based ceramics are used as examples to demonstrate the calculation and experimental procedures and the comparisons with the standard methods.
TL;DR: In this article, the ternary system of lead nickel niobate Pb(Ni1/3Nb2/3)O3 (PNN), PZN, and PZT was investigated to determine the influence of different solid state processing conditions on dielectric and ferroelectric properties.
Abstract: The ternary system of lead nickel niobate Pb(Ni1/3Nb2/3)O3 (PNN), lead zinc niobate Pb(Zn1/3Nb2/3)O3 (PZN), and lead zirconate titanate Pb(Zr1/2Ti1/2)O3 (PZT) was investigated to determine the influence of different solid state processing conditions on dielectric and ferroelectric properties. The ceramic materials were characterized using x-ray diffraction, dielectric measurements, and hysteresis measurements. To stabilize the perovskite phase, the columbite route was utilized with a double crucible technique and excess PbO. The phase-pure perovskite phase of PNN–PZN–PZT ceramics was obtained over a wide compositional range. It was observed that for the ternary system 0.5PNN–(0.5 - x)PZN–xPZT, the change in the transition temperature (Tm) is approximately linear with respect to the PZT content in the range x [H11505] 0 to 0.5. With an increase in x, Tm shifts up to high temperatures. Examination of the remanent polarization (Pr) revealed a significant increase with increasing x. In addition, the relative permittivity ([H9280]r) increased as a function of x. The highest permittivities ([H9280]r [H11505] 22,000) and the highest remanent polarization (Pr [H11505] 25 μC/cm2) were recorded for the binary composition 0.5Pb(Ni1/3Nb2/3)O3–0.5Pb(Zr1/2Ti1/2)O3.
TL;DR: In this article, Yttria-doped zirconia, barium titanate (PZT), and lead-zirconate titanate powders were synthesized using hydrothermal procedures.
Abstract: Yttria-doped zirconia, lead zirconate titanate (PZT) and barium titanate were successfully obtained using hydrothermal procedures. Based on these results mathematical models describing the correlation between the nanopowders' characteristics and the main synthesis parameters are proposed. Powders from the systems (Y2O3)0.1 (ZrO2)0.9 and (Y2O3)0.04 (ZrO2)0.96 obtained from soluble Zr(IV) peroxide precursors show that cubic/tetragonal phases have been formed by controlled crystallization from the solution. With increasing temperature and hydrothermal treatment temperature the mean crystallite sizes increase from a minimum of 5 nm to a maximum of 22 nm. The activation energy shows a diffusion-controlled process. Barium titanate powders with controlled stoichiometry could also be hydrothermally synthesized in the temperature range 110– 175°C. Synthesis of PZT powders with controlled stoichiometry and mean crystallite sizes from 4 to 43 nm is finally presented. Dense yttria-partial stabilized zirconia with high ionic conductivity and PZT with a good stability of electric–physical parameters for use in the design of materials with improved sensorial characteristics was obtained after sintering the nanopowders.
TL;DR: In this article, the early stages of nucleation and growth and texture development of the perovskite phase in PZT(52/48) seeded and unseeded sol−gel thin films were reported.
Abstract: This article reports on the early stages of nucleation and growth and texture development of the perovskite phase in PZT(52/48) seeded and unseeded sol−gel thin films. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) revealed that, in seeded films, the perovskite phase nucleates and grows at the film surface, on seed particles and at the Pt/PZT interface. In contrast, for unseeded films, nucleation and growth of the perovskite phase only occurs from the PZT/Pt interface. At low pyrolysis temperatures, the crystalline nucleation density is much higher in seeded than in unseeded films. The perovskite phase formation process is consequently accelerated by the presence of seeds. PZT thin films with 1 mol % seeds pyrolyzed at 430 °C for 40 h exhibit a dielectric permittivity of 500 and Pr and Ec of 6.71 μC/cm2 and 80 kV/cm, respectively. Seeded PZT films heat-treated at low temperatures (around 400 °C) may be suitable for applications in which deposition is required onto glass, metallic, or p...
TL;DR: In this article, the formation of double-peak profiles of Pb(Zr0.52Ti0.48)O3 thin films was studied using the same framework used to understand the imbibition and wetting of the sol-gel in the capillary channels.
Abstract: The patterning of sol-gel-derived thin films by micromolding in capillaries can produce unintended topographical deviations from the shape of the original mold that may limit the utility of the technique in potential applications. During drying and heat treatment, nonuniform shrinkage across the film due to the densification of the gel matrix results in “double-peak” film topographies whereby the film thickness is greater at the lateral edges than in the middle. Using the same framework used to understand the imbibition and wetting of the sol-gel in the capillary channels, we developed a mechanism to explain the formation of the double-peak profile. As a model system, patterned Pb(Zr0.52Ti0.48)O3 thin films were studied. Atomic force microscopic characterization was used to quantify the effect of the rate of gelation on the topography of the patterned thin films. Modifications to the channel mold design eliminate the peak formation, producing more homogeneous patterns that better replicate the features of the mold.
TL;DR: In this paper, a phenomenological thermodynamic theory is employed to explain the electric field dependence of piezoelectric properties of tetragonal single domain PbZrxTi1−xO3 (PZT) thin films.
Abstract: Landau–Devonshire-type phenomenological thermodynamic theory is employed to explain the electric field dependence of piezoelectric properties of tetragonal single domain PbZrxTi1−xO3 (PZT). The strong nonlinearity of the converse piezoelectric coefficient under a large external electric field is proved to be intrinsic both in bulk crystal and epitaxial tetragonal PZT thin films. The tunability of piezoelectric responses by an external electric field and its dependence on the film/substrate misfit and elastic compliance of thin films are characterized quantitatively. The theoretical predictions are in good agreement with the experimental results of piezoresponse scanning microscopy. Due to the large tunability of piezoresponse in it, PZT 50/50 (x=0.5) epitaxial film is a promising candidate for use in future tunable devices.
TL;DR: In this article, a thin film layered magnetoelectric composites consisting of ferromagnetic and ferroelectric phases have been synthesized with nickel ferrite, cobalt ferrite (CFO), La 0.7Sr0.3MnO3 (LSMO), or lead zirconate titanate (PZT).
Abstract: Thick film layered magnetoelectric composites consisting of ferromagnetic and ferroelectric phases have been synthesized with nickel ferrite (NFO), cobalt ferrite (CFO), La0.7Sr0.3MnO3 (LSMO), or La0.7Ca0.3MnO3 (LCMO) and lead zirconate titanate (PZT). Structural, magnetic and ferromagnetic resonance characterization shows evidence for defect free ferrites, but deterioration of manganite parameters. The resistivity and dielectric constants are smaller than expected values. The magnetoelectric effect (ME) is stronger in ferrite-PZT than in manganite-PZT. The ME voltage coefficient aE at room temperature is the highest in NFO-PZT and the smallest for LCMO-PZT. The transverse ME effect is an order of magnitude stronger than the longitudinal effect. The magnitude of aE correlates well with magnetic permeability for the ferrites.
TL;DR: In this article, the effects of uniaxial stress on the dielectric properties of ceramics in lead magnesium niobate-lead zirconate titanate (PMN-PZT) system are investigated.
Abstract: Effects of uniaxial stress on the dielectric properties of ceramics in lead magnesium niobate–lead zirconate titanate (PMN–PZT) system are investigated The ceramics with a formula (x)Pb(Mg1/3Nb2/3)O3–(1−x)Pb(Zr052Ti048)O3 or (x)PMN–(1 − x)PZT when x = 00, 01, 03, 05, 07, 09, and 10 are prepared by a conventional mixed-oxide method Phase formation behaviour and microstructural features of these ceramics are studied by x-ray diffraction and scanning electron microscopy methods, respectively The dielectric properties under the uniaxial stress of the PMN–PZT ceramics are observed at stress levels up to 5 MPa using a uniaxial compressometer It is found that with increasing applied stress the dielectric constant of the PZT-rich compositions increases slightly, while that of the PMN-rich compositions decreases On the other hand, the dielectric loss tangent for most of the compositions first rises and then drops with increasing applied stress
TL;DR: In this article, the effect of DC bias field on the complex piezoelectric, dielectric and elastic coefficients of a lead zirconate titanate ceramic resonator was investigated.
Abstract: In many practical applications, piezoelectric devices are driven under strong electric field or under DC bias field. To evaluate the performance of the piezoelectric devices under these strong field conditions, the materials constants measured under weak field are usually not applicable. In this paper, we report our measurement results on the effect of DC bias field on the complex piezoelectric, dielectric and elastic coefficients of piezoelectric lead zirconate titanate ceramic resonator. A thin plate soft PZT resonator (transverse mode) is used in this study. A recently developed accurate method is used to directly characterize the complex materials coefficients, in which for a thin plate PZT resonator with length extensional vibration mode, normalized electric admittance, Y (=Y/ω) instead of admittance Y spectrum is used to determine the materials coefficients under various DC bias fields applied along the polarization direction. It has been found that with DC bias field increasing, elastic compliance, piezoelectric coefficient and dielectric permittivity decrease with approximately linear relationships. Second-order electromechanical coefficients can be estimated through the measurement of materials coefficients under DC bias conditions. Based on the observation of frequency increasing with DC bias field, it is suggested that the DC bias field can be used for frequency tuning or frequency–temperature compensation.
TL;DR: In this paper, poly(ethylene glycol) additives with different molecular weights were used to modify sol-gel precursor solutions for preparing lead zirconate titanate (PZT) thin films.
Abstract: Poly(ethylene glycol) (PEG) additives with different molecular weights were used to modify sol-gel precursor solutions for preparing lead zirconate titanate (PZT) thin films. The morphology, crystalline structure, and mechanical and electrical properties of the films were characterized. The relationship between the characteristics of the films and the molecular weight of PEG was investigated. It was observed that the PEG eliminated cracking of the films during multiple pyrolysis treatments. However, with the increase of the PEG molecular weight, the films became less dense, which led to decreased Young's modulus and dielectric constant and increased coercive field. Our experiments showed that films prepared from sols modified by PEG with a molecular weight of 200 exhibited a dense morphology and excellent mechanical and electric properties without cracking.