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Showing papers on "Lead zirconate titanate published in 2005"


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the properties of lead zirconate titanate (PZT) ceramics over the grain-size range of 0.1-10 μm.
Abstract: The processing, electromechanical properties, and microstructure of lead zirconate titanate (PZT) ceramics over the grain-size range of 0.1-10 μm were studied. Using measurements over a large temperature range (15-600 K), the relative role of extrinsic contribution (i.e., domain-wall motion) was deduced to be influenced strongly by the grain size, particularly for donor-doped PZT. Analytical transmission electron microscopy studies were conducted to investigate the trend in domain configurations with the reduction of grain size. The correlations between domain density, domain variants, domain configurations (before and after poling), spontaneous deformation, and the elastodielectric properties were qualitatively discussed, leading to new insights into the intrinsic and extrinsic effects and relevant size effects in ferroelectric polycrystalline materials.

918 citations


Journal ArticleDOI
TL;DR: In this paper, a cantilever device is designed to have a flat structure with a proof mass added to the end to create electrical energy via the piezoelectric effect.
Abstract: A thin film lead zirconate titanate, Pb(Zr,Ti)O 3 (PZT), MEMS power generating device is developed. It is designed to resonate at specific frequencies from an external vibrational energy source, thereby creating electrical energy via the piezoelectric effect. Our cantilever device is designed to have a flat structure with a proof mass added to the end. The Pt/Ti top electrode is patterned into an interdigitated shape on top of the sol–gel-spin coated PZT thin film in order to employ the d33 mode of the piezoelectric transducer. This d33 mode design generates 20 times higher voltage than that of the d31 mode design of the same beam dimension. The base-shaking experiments at the first resonant frequency (13.9 kHz) generate charge proportional to the tip displacement of the cantilever with a linearity coefficient of 4.14 pC/ m. A

825 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the enhanced piezoelectric response along nonpolar directions, observed in many perovskite systems, is a consequence of the flattening of the Gibbs free energy profile.
Abstract: The piezoelectric effect in ferroelectric single crystals and ceramics is investigated considering intrinsic (lattice), and extrinsic (originating mainly from displacement of domain walls) contributions. The focus of the study of intrinsic properties is on piezoelectric anisotropy, which was examined using the Landau-Ginsburg-Devonshire phenomenological theory. It is shown that the enhanced piezoelectric response along nonpolar directions, observed in many perovskite systems, is a consequence of the flattening of the Gibbs free energy profile. This flattening is common for temperature-, composition-, and external field-induced enhancement of the piezoelectric properties along nonpolar axes. A brief review of recent advances in understanding the origins of the piezoelectric nonlinearity, hysteresis, and frequency dispersion is also given.

527 citations


Journal ArticleDOI
TL;DR: In this paper, it is shown that it is possible to process lead zirconate (Pb(Zr0.52Ti0.48)O3) thin films directly on base metal copper foils.
Abstract: Replacement of noble metal electrodes by base metals significantly lowers the cost of ferroelectric, piezoelectric and dielectric devices. Here, we demonstrate that it is possible to process lead zirconate (Pb(Zr0.52Ti0.48)O3, or PZT) thin films directly on base metal copper foils. We explore the impact of the oxygen partial pressure during processing, and demonstrate that high-quality films and interfaces can be achieved through control of the oxygen partial pressure within a narrow window predicted by thermodynamic stability considerations. This demonstration has broad implications, opening up the possibility of the use of low-cost, high-conductivity copper electrodes for a range of Pb-based perovskite materials, including PZT films in embedded printed circuit board applications for capacitors, varactors and sensors; multilayer PZT piezoelectric stacks; and multilayer dielectric and electrostrictive devices based on lead magnesium niobate–lead titanate. We also point out that the capacitors do not fatigue on repeated switching, unlike those with Pt noble metal electrodes. Instead, they appear to be fatigue-resistant, like capacitors with oxide electrodes. This may have implications for ferroelectric non-volatile memories.

268 citations


Journal ArticleDOI
TL;DR: In this article, the authors show that the small-signal value of the elastic constant s is not sufficient to describe the complicated behavior of lead zirconate titanate (PZT) ceramics.
Abstract: To increase the reliability of multilayer actuators, calculation of the mechanical stress inside the device during operation is important. This paper shows that the small-signal value of the elastic constant s is not sufficient to describe the complicated behavior of lead zirconate titanate (PZT) ceramics. Therefore, compressive strain and depolarization have been measured as a function of large-signal stress applied parallel to the poling direction. The nonlinear dependence of the strain and depolarization can clearly be explained by domain processes. Soft and hard PZT ceramics have been investigated. In hard PZT, domain switching appears at higher stresses than in soft PZT. Moreover, in hard PZT, the domains partly switch back during unloading. The critical stress (coercive stress) necessary for a domain-switching process shows a dependence on the Zr:Ti ratio that is quite similar to the dependence of the electric coercive field. The influence of an electric field applied parallel to the poling direction and superimposed on the compression experiment also has been examined. The coercive stress depends linearly on the electric field. The linear coefficient of this relation is given by the ratio of depolarization to compressive strain caused by domain switching.

259 citations


Journal ArticleDOI
TL;DR: In this article, the flexoelectric coefficient of lead zirconate titanate (PZT) ceramics was measured to be 1.4μC∕m in the PZT ceramic at small level of strain gradient.
Abstract: Mechanical strain gradient generated electric polarization or flexoelectric effect was investigated in unpoled lead zirconate titanate (PZT) ceramics in the ferroelectric state by using a cantilevered beam based approach. Flexoelectric coefficient μ12 at room temperature was measured to be 1.4μC∕m in the PZT ceramic at small level of strain gradient. Temperature-dependent experimental investigations clearly showed that high dielectric permittivity in the ferroelectrics enhanced flexoelectric polarization: essentially a linear relation was found to exist between μ12 and dielectric susceptibility χ at lower permittivity level (2100–2800), while μ12 versus χ curve started to deviate from the straight line at the χ∼2800 and nonlinear enhancement of μ12 with χ was observed, with μ12 value reaching 9.5 at χ∼11000. The nonlinearity in the flexoelectric effect was associated with domain-related processes. It is suggested that flexoelectric effect can have a significant impact on epitaxial ferroelectric thin films and mesoscopic structures.

242 citations


Journal ArticleDOI
TL;DR: In this article, the relative intensity ratio of ferroelectric poles in poled and unpoled lead zirconate titanate was used to calculate a domain switching fraction (η) or a multiple of a random distribution, which are linearly related.
Abstract: The domain structure of ferroelectric ceramics can be altered by the process of electrical poling. This paper develops quantitative approaches for reflection geometry and spherical harmonic texture analysis, both of which describe these changes at angles parallel to and tilted from the poling axis. The x-ray-diffraction approach uses the relative intensity ratio of ferroelectric poles in poled and unpoled lead zirconate titanate to calculate a domain switching fraction (η) or a multiple of a random distribution, which are shown to be linearly related. An x-ray area detector diffractometer was used for these measurements, although the technique applies to any x-ray reflection geometry. The neutron-diffraction approach employs a Rietveld refinement with a spherical harmonic texture model. Both approaches calculate similar domain textures for two poling fields and the small differences between the approaches can be attributed to surface domain texture. This paper shows that the March–Dollase pole distributio...

198 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of preload stress on the ferroelectric hysteretic behavior of piezoelectric ceramics was investigated for soft lead zirconate titanate (PZT) material under various uniaxial compressive stress preloads.
Abstract: This paper deals with the influence of preload stress on the ferroelectric hysteretic behavior of piezoelectric ceramics. The polarization and strain versus electric field hysteresis loops were measured for soft lead zirconate titanate (PZT) piezoceramic material under various uniaxial compressive stress preloads of up to −400 MPa. The investigation revealed that the superimposed compression load reduced the remnant polarization, decreased the coercive field, and also had a significant impact on the dielectric and piezoelectric properties. With increasing mechanical load, dielectric hysteresis and butterfly hysteresis became less and less pronounced, as the compressive stress prevented full alignment of the domains and induced mechanical depolarization. The slopes of the polarization and strain curves at zero electric field were measured to evaluate the dependence of permittivity and piezoelectric coefficients on the prestress. The experimental results were interpreted in terms of the non-180° domain switching process under combined electromechanical loading.

197 citations


Journal ArticleDOI
TL;DR: In this article, a review on the multiple loading scenarios that lead to asymmetries in material response and loss in performance is presented, and the disparities between unipolar, bipolar, and mixed electromechanical loading are displayed.
Abstract: Fatigue in ferroelectric ceramics is the gradual change of material properties with cyclic loading. It is caused by microscopic material modifications of mechanical or electrical origin. Due to the electromechanical coupling, both mechanisms can yield similar or even identical changes in properties. Macroscopically, a reduction of switchable polarization is anticipated and asymmetries in the macroscopic hysteresis curves arise due to charge carrier migration. This review elaborates on the multiple loading scenarios that lead to asymmetries in material response and loss in performance. The disparities between unipolar, bipolar, and mixed electromechanical loading are displayed. Possible microscopic origins are categorized. The strong similarities in the roles of microcracks, dielectric layers, and grain boundaries are worked out.

151 citations


Journal Article
TL;DR: In this paper, a review of the multiple loading scenarios that lead to asymmetries in material response and loss in performance is presented, and the disparities between unipolar, bipolar, and mixed electromechanical loading are displayed.
Abstract: Fatigue in ferroelectric ceramics is the gradual change of material properties with cyclic loading. it is caused by microscopic material modifications of mechanical or electrical origin. Due to the electromechanical coupling, both mechanisms can yield similar or even identical changes in properties. Macroscopically, a reduction of switchable polarization is anticipated and asymmetries in the macroscopic hysteresis curves arise due to charge carrier migration. This review elaborates on'the multiple loading scenarios that lead to asymmetries in material response and loss in performance. The disparities between unipolar, bipolar, and mixed electromechanical loading are displayed. Possible microscopic origins are categorized. The strong similarities in the roles of microcracks, dielectric layers, and strain boundaries are worked out.

143 citations


Journal ArticleDOI
TL;DR: In this article, a new 0-3 type cement-based PZT composite is presented, where up to 50 vol.% lead zirconate titanate powder can be easily incorporated into the composites.
Abstract: In this paper, studies on a new 0–3 type cement-based PZT (lead zirconate titanate) composite are presented. Using a normal mixing and compacting method, up to 50 vol.% PZT ceramic powder can be easily incorporated into the composites. The behaviors of the cement-based PZT composites under different polarizing conditions have been investigated on the piezoelectric properties both theoretically and experimentally. It shows that cement-based PZT composites have their own unique characteristics. There is a good potential for the application of 0–3 type cement based piezoelectric composites in civil engineering.

Journal ArticleDOI
TL;DR: In this article, the authors used a fused deposition (FD) technique to fabricate lead zirconate titanate (PZT)/polymer composites, which showed excellent electromechanical properties for transducer applications.
Abstract: Piezoelectric ceramic/polymer composites were made by a fused deposition (FD) technique, which is a solid-freeform fabrication (or layered manufacturing) technique where three-dimensional (3-D) objects are built layer by layer from a computer-aided design (CAD) file on a computer-controlled fixtureless platform. Indirect and direct FD methods were used to fabricate lead zirconate titanate (PZT)/polymer composites. For the indirect method, a CAD file for the negative image of the final part was created. A polymer mold was made via FD using a thermoplastic filament, and composite formation was completed via a lost mold technique. In the direct FD method, a thermoplastic polymeric filament that was filled with 50–55 vol% of PZT powder was used to form a positive image of the desired structure. Three-dimensional honeycomb (“3-D honeycomb”) composites and “ladder” composites with 3-3 connectivity, which were formed via the FD technique, showed excellent electromechanical properties for transducer applications. In addition, the FD technique showed the ability to form composites with controlled phase periodicity, various volume fractions, and a variety of microstructures and macrostructures that are not possible with traditional composite-forming techniques.

Journal ArticleDOI
TL;DR: Using piezoelectric diagnostics, the authors in this article measured densities and velocities of ejected particulate as well as free surface velocity of bulk tin targets loaded with high explosive.
Abstract: Using piezoelectric diagnostics, we have measured densities and velocities of ejected particulate as well as “free-surface velocities” of bulk tin targets shock loaded with high explosive. The targets had finely grooved, machined finishes ranging from 10 to 250μin. Two types of piezoelectric sensor (“piezopins”), lithium niobate and lead zirconate titanate, were compared for durability and repeatability; in addition, some piezopins were “shielded” with foam and metal foil in order to mitigate premature failure of the pins in high ejecta regimes. These experiments address questions about ejecta production at a given shock pressure as a function of surface finish; piezopin results are compared with those from complementary diagnostics such as x-ray radiography and time-resolved optical transmission techniques. The mass ejection shows a marked dependence on groove characteristics and cannot be described by a groove defect theory alone.

Journal ArticleDOI
TL;DR: In this paper, the effects of multi-coating processes on the orientation, microstructure and electrical property of lead zirconate titanate (PZT) thick films derived by chemical solution deposition were described.

Journal ArticleDOI
TL;DR: In this paper, the dielectric and ferroelectric properties of pure-phase PZT and PMN are measured by means of an automated dielectrics measurement set-up and a modified Sawyer-Tower circuit, respectively.
Abstract: The dielectric and ferroelectric properties of ( x )Pb(Mg 1/3 Nb 2/3 )O 3 –(1 − x ) Pb(Zr 0.52 Ti 0.48 )O 3 (where x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) ceramics prepared by an oxide-mixing method are measured by means of an automated dielectric measurement set-up and a modified Sawyer-Tower circuit, respectively. The dielectric properties of the ceramics are measured as functions of both temperature and frequency. The results indicate that the dielectric properties of the pure-phase PZT and PMN are of normal and relaxor ferroelectric behaviors, respectively. The dielectric behaviors of the 0.1PMN–0.9PZT and 0.3PMN–0.7PZT ceramics are more of normal ferroelectrics, while the other compositions are obviously of relaxor ferroelectrics. In addition, the transition temperature decreases and the maximum dielectric constant increases with increasing PMN content in the system. The P – E hysteresis loop measurements demonstrate that the ferroelectric properties of the ceramics in PMN–PZT system change gradually from the normal ferroelectric behavior in PZT ceramic to the relaxor ferroelectric behavior in PMN ceramic. These results clearly show the significance of PMN in controlling the electrical responses of the PMN–PZT system.

Journal ArticleDOI
TL;DR: In this article, the structural, ferroelectric and optical properties of lead zirconate titanate (PZT) thin films (with a molar ratio of Zr:Ti::65:35) deposited by sol-gel technique on ITO-coated corning 7059 glass substrates were reported.
Abstract: We report on the structural, ferroelectric and optical properties of lead zirconate titanate (PZT) thin films (with a molar ratio of Zr:Ti::65:35) deposited by sol–gel technique on ITO-coated corning 7059 glass substrates. A seed layer of PbTiO3 (0.1mm) was coated by sol–gel on the substrates before depositing PZT. A metal/ferroelectric/metal (MFM) structure was used for electrical property measurements, formed by depositing gold electrodes on top of the film. The films were characterized for C–V, I–V, P–E and optical transmission. Relatively low remnant polarization (Pr ¼ 3:6mC=cm 2 ) was observed for the films. Value of optical band gap was found to be 3.4 eV. The results are discussed.

Journal ArticleDOI
TL;DR: In this paper, the authors carried out impedance analysis on compensated bulk lead zirconate titanate samples and found that the highly compensated nature of these samples minimizes the role of oxygen vacancies.
Abstract: Impedance analysis studies were carried out on compensated bulk lead zirconate titanate samples. Fatigue is concomitant with the onset of dielectric loss. This is shown to be dominantly due to an irreversibly modified near-surface layer that can be polished off. The highly compensated nature of these samples minimizes the role of oxygen vacancies.

Journal ArticleDOI
TL;DR: In this article, the evolution of domain populations as a function of the Zr content x was analyzed using piezoforce microscopy (PFM) and showed that PFM histograms are extremely sensitive to PZT composition and can be used as a signature of complex domain structures.
Abstract: Pb (ZrxTi1−x)O3 (PZT) thin films with (111) texture were deposited onto commercially available Pt/Ti/SiO2/Si substrates via the sol–gel technique. Piezoforce microscopy (PFM) was then used to analyse the evolution of domain populations as a function of the Zr content x. Domain structures of virgin films, local piezoelectric properties of individual grains and piezoelectric histograms were studied in films with different compositions (x = 0.2–0.6), which cover both the tetragonal and rhombohedral sides of the phase diagram. In films with low Zr content mainly single-domain grains were observed. As the Zr content increased, a larger fraction of polydomain grains was found. The local piezoelectric response measured inside sufficiently big grains indicated that the strongest piezoelectric effect occurs in PZT30/70 (x = 0.3) films. This was attributed to two different effects: high out-of-plane polarization achieved due to the (111) texture and influence of the dielectric constant. In tetragonal films with their lower dielectric constants the electric field seen by a ferroelectric is higher as compared to other compositions, giving rise to an apparent increase of the effective piezoelectric response measured by PFM. The analysis of the domain images indicated that sol–gel derived PZT films are slightly self-polarized near the free surface. With increasing Zr/Ti ratio, the variation of domain populations resulted in reversing the sign of the average piezoelectric response at x≈0.3. It is demonstrated that PFM histograms are extremely sensitive to PZT composition and can be used as a signature of complex domain structures in ferroelectric thin films.

Journal ArticleDOI
TL;DR: In this article, the effect of the process parameters such as deposition time and voltage as well as the solidsloading of the colloidal suspensions on the quality, thickness and microstructure of the different ceramic films produced is discussed.
Abstract: Electrophoretic deposition (EPD) has been used in the present work to produce thick ceramic films from nanosized powders on different substrates for structural and functional applications. Hydrothermally synthesized ultra-fine (12 nm) yttrium disilicate (Y2Si2O7) powders were used to create an effective oxidation protection layer of 90 μm thickness on bulk SiC/SiC composite and on woven SiC fibre mats by EPD using a constant voltage of 8 V for 1.5 min. EPD was also used to make lead zirconate titanate (PZT) films on Pt wires for functional applications using hydrothermally synthesized PZT powders with an average particle size of 200 nm. EPD was employed to deposit PZT films directly from the hydrothermal PZT suspensions using a deposition voltage of 4 V for 10 min, leading to the formation of a functional PZT film with a thickness of 5 μm around Pt wire. Titania films on different stainless steel substrates (plates, individual fibres, fibre mats) were also produced by EPD at constant voltage conditions. A nonaqueous suspension of TiO2 nanoparticles in acetylacetone with iodine additions was used for optimal results, which were obtained using voltages of 10 V and deposition times of 2 min. Sintering at 800 °C for 2 h resulted in TiO2 coatings with uniform nanoporous structure, which are interesting for biomedical and photocatalytic applications. The effect of the process parameters such as deposition time and voltage as well as the solids-loading of the colloidal suspensions on the quality, thickness and microstructure of the different ceramic films produced is discussed.

Journal ArticleDOI
TL;DR: In this paper, an analytical model of the curved PZT unimorph was developed using shallow thin shell theory and linear piezoelectric constitutive equations to maximize charge generation due to mechanical loading.
Abstract: The piezoceramic, lead zirconate titanate (PZT), is capable of producing large voltages with relatively minimal currents in response to an applied mechanical load when employed in initially curved laminates. This study addresses the issue of optimizing design parameters of a curved PZT unimorph to maximize charge generation due to mechanical loading. A horizontally placed PZT unimorph structure generates surface charge when vertically loaded and the charge can be collected using charge-collecting circuitry. In order to identify and optimize the variables fundamental to the design process, an analytical model of the curved PZT unimorph was developed using shallow thin shell theory and linear piezoelectric constitutive equations. An expression for charge generation was then derived in terms of geometrical dimensions, material properties and applied loading. The model was experimentally verified with samples consisting of different geometries and loadings. Finally, the analytical model was used to generate o...

Journal ArticleDOI
TL;DR: In this article, the authors performed ac and dc conductivity measurements under ambient atmosphere on doped lead zirconate titanate (PZT) ceramics in order to investigate the defect chemistry by identifying the predominant charge carriers.
Abstract: In this study, ac and dc conductivity measurements were performed under ambient atmosphere on doped lead zirconate titanate (PZT) ceramics in order to investigate the defect chemistry by identifying the predominant charge carriers. The considered compositions were acceptor (1% mol Mn or Mg) and donor (Nb or F) co-doped PZTs with [Donor] = 1 or 2% mol. The influence of donor concentration on the conductivity was determined. From the conduction activation energy values calculated in the temperature range 200–700 °C, the principal contributing charge carriers are doubly-ionized oxygen V O ¨ and lead vacancies VPb. For Mg doped PZTs, neither Nb nor F co-doping strongly reduce both conductivity levels and the dominant conducting species V O ¨ . For Mn doped materials, both donor co-dopants niobium and fluorine reduce the conductivity but do not have the same effect on the conduction mechanism at low temperature. With 2% Nb doping, the dominant conducting species are V O ¨ whereas electrical conduction is controlled by electrons from the second-ionization of oxygen vacancies with 2% F doping. The difference of oxygen vacancies content in (Mn, F) and (Mn, Nb) co-doped PZTs may be at the origin of the two distinct conducting species and of the different conductivity levels.

Journal ArticleDOI
TL;DR: In this article, the influence of the uniaxial bias stress on the piezoelectric properties of tetragonal BaTiO3 and PbTiOO3 monodomain crystals is modeled in the framework of the phenomenological Landau-Ginzburg-Devonshire theory.
Abstract: The influence of the uniaxial bias stress on the piezoelectric properties of tetragonal BaTiO3 and PbTiO3 monodomain crystals is modeled in the framework of the phenomenological Landau-Ginzburg-Devonshire theory. It is shown that tensile and compressive stresses, both applied along the spontaneous polarization direction, reduce and enhance the piezoelectric response, respectively. The enhancement effect is due to the flattening of the free-energy profile and the corresponding dielectric softening of crystals, caused by the compressive stress. In BaTiO3 crystals, at temperatures close to the tetragonal-orthorhombic phase transition temperature, the free-energy profile flattening and dielectric softening are the largest along axes perpendicular to the polarization direction, facilitating thus the polarization rotation away from the [001](c) polar axis. The resulting enhancement of the shear piezoelectric coefficient is directly responsible for the increase of the longitudinal piezoelectric coefficient along the [111](c) axis. At temperatures deep within the tetragonal phase in BaTiO3, and over the whole ferroelectric region of PbTiO3, the flattening of the free-energy profile and the dielectric softening by compressive stress are the strongest along the polar axis. The resulting enhancement of the longitudinal piezoelectric coefficient is thus the largest along the polar [001](c) direction. These results, which can be applied to other perovskite crystals, have broad implications.

Journal ArticleDOI
TL;DR: In this article, the authors present systematic measurements of the non-linear depolarization and strain behavior of soft lead zirconate titanate piezoceramics over a wide range of compression loads and bias electric fields.
Abstract: Modern piezoelectric transducers normally have complicated structures and work under severe loading conditions. Due to their inherent domain-switching processes, the real response of piezoceramics under large-signal loading is dominated by a significantly non-linear behavior that is to be considered in reliability assessment and devices design. This paper presents systematic measurements of the non-linear depolarization and strain behavior of soft lead zirconate titanate piezoceramics over a wide range of compression loads and bias electric fields. An attempt has been made to explain the experimental findings by simultaneously taking into account the contributions of dielectric response, elastic deformation, irreversible domain switching, and piezoeffects.

Journal ArticleDOI
TL;DR: The strength of magnetoelectric (ME) coupling at 10Hz-3MHz has been measured in trilayers of Fe, Co, or Ni and lead zirconate titanate (PZT) as discussed by the authors.
Abstract: The strength of magnetoelectric (ME) coupling at 10Hz–3MHz has been measured in trilayers of Fe, Co, or Ni and lead zirconate titanate (PZT). The strongest ME coupling is measured for trilayers with Ni and the weakest in Co. Data on ME voltage coefficient αE versus bias magnetic field H for Fe–PZT–Fe show unique features including zero crossing and sign reversal. Measurements of frequency dependence of αE reveal a giant ME coupling due to the electromechanical resonance at 200–300kHz for radial modes and at ∼2.7MHz for thickness modes. Theoretical estimates of field and frequency dependence of αE are in very good agreement with the data.

Journal ArticleDOI
TL;DR: In this paper, a review is given of single-crystal thin film ferroelectric oxides, emphasizing perovskite phases, together with some new developments on hafnia films.
Abstract: A review is given of ceramic and single-crystal thin film ferroelectric oxides, emphasizing perovskite phases, together with some new developments on hafnia films. It is shown that single-crystal barium titanate films behave as bulk down to at least 77 nm, with no finite size effects, no phase transition temperature shifts, and no dielectric peak broadening or change from first- to second-order transitions, suggesting that the gradient defect model of Bratkovsky and Levanyuk correctly describes such effects as extrinsic in experimental studies of equally thin ceramic thin films. In ceramic barium–strontium titanate (BST) thin films, it is shown that there is also no intrinsic broadening or shifts in phase transitions, with sharp, unshifted, bulk-like transitions observed only as re-entrant upon warming from cryogenic temperatures; this shows that phase transitions in ceramic thin films are dominated by kinetics and not thermodynamics and are definitely not equilibrium measurements. At high fields (>1 GV/m), the films exhibit space charge-limited conduction; no variable-range hopping is observed, contrary to recent studies on SrTiO3. Some novel, unconventional switching processes are discussed, comparing the “perimeter effect” (non-equilibrium, ballistic) with Molotskii's equilibrium model. Theory and experiment are described for [3D] nanotubes, nanorods, and nano-ribbons (or micro-ribbons). The layered-structure-perovskite–pyrochlore conversion in bismuth titanate is described together with the PbO+TiO2 phase separation in lead zirconate titanate during electrical breakdown, as are novel HfO2 precursors that demonstrate enhanced temperature crystallization from the amorphous state and hence commercial advantages for front-end processing.

Journal ArticleDOI
TL;DR: In this paper, the Curie temperatures of lead zirconate titanate-based (PZT-based) composites that were incorporated with silver particles were evaluated as a function of the silver content.
Abstract: The Curie temperatures of lead zirconate titanate-based (PZT-based) composites that were incorporated with silver particles were evaluated as a function of the silver content. Although the substitution of the silver ion has been considered to decrease the Curie temperature, PZT/silver composites exhibited higher Curie temperatures than those of monolithic PZT ceramics. It was found that the Curie temperature gradually increased as the silver content increased. It was suggested that the observed Curie temperature anomaly resulted from the relaxation of transformation-induced internal stress by intergranular silver particles.

Journal ArticleDOI
TL;DR: In this paper, the electrical properties of both lanthanum-doped and undoped PZT fibers were measured and were comparable to bulk disks fabricated using powder derived from the same sol.
Abstract: Fine-scale fibers with diameters 650°C were needed to achieve phase-pure perovskite fibers. Dense fibers with diameters of 10-70 µm and grain sizes <1 µm were found with sintering temperatures up to 1000°C. Increasing the firing temperature to 1200°C for 30 min resulted in grain growth up to 2.5 µm. Electrical properties of both lanthanum-doped and undoped PZT fibers were measured and were comparable to bulk disks fabricated using powder derived from the same sol.

Journal ArticleDOI
TL;DR: Piezoelectric micromachined ultrasonic transducers, a potential alternative for conventional one-dimensional phased array ultrasonic Transducers, were investigated and modeling results indicate that the coupling coefficient is significantly affected by silicon membrane, PZT, and top electrode thickness as well as the top electrode design.
Abstract: Piezoelectric micromachined ultrasonic transducers (pMUTs), a potential alternative for conventional one-dimensional phased array ultrasonic transducers, were investigated. We used a modeling approach to study the performance of lead zirconate titanate (PZT)-driven pMUTs for the frequency range of 2-10 MHz, optimized for maximum coupling coefficient, as a function of device design. Using original tools designed for the purpose, a comprehensive build-test finite element model was developed to predict and measure the device performance. In particular, the model estimates the device coupling coefficient and the acoustic impedance, besides the readily extractable resonance frequency and bandwidth. To validate the model, a prototype device was built and tested, showing good agreement between the model predictions and experimental results. Modeling results indicate that the coupling coefficient is significantly affected by silicon membrane, PZT, and top electrode thickness as well as the top electrode design. Results also indicate considerable flexibility in maximizing the coupling coefficient while maintaining the device acoustic impedance at a level matching that of the human body. The bandwidth proved to be superior to that of conventional transducers, reaching 102% in some cases.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate films of the well-known ferroelectric lead zirconate titanate (PZT) prepared directly on copper foils by chemical solution deposition (CSD).
Abstract: We demonstrate films of the well-known ferroelectric lead zirconate titanate (PZT) prepared directly on copper foils by chemical solution deposition (CSD). The films exhibit saturating polarization hysteresis, remanent polarization values of 26μC∕cm2, and permittivities of 800; these properties are comparable to those achieved using semiconductor-grade substrates. The preparation methodology is founded upon an understanding of solution chemistry as opposed to conventional gas-phase ∕ condensed-phase equilibrium approaches. By adopting this technique, base-metal compatibility can be achieved using much lower temperatures, and a broader set of devices can be prepared offering intimate contact with high conductivity, easily patternable, or ferromagnetic metals.

Journal ArticleDOI
TL;DR: In this article, the authors measured pseudodielectric functions in the visible-deep ultraviolet spectral range of Pb(ZrxTi1−x)O3 (x=0.56, 0.82) (PZT), Pb0.96O3, Pb 0.91La0.09(Zr0.65Ti0.35)0.98Nb0
Abstract: We measure pseudodielectric functions in the visible-deep ultraviolet spectral range of Pb(ZrxTi1−x)O3 (x=0.2,0.56,0.82) (PZT), Pb0.98Nb0.04(Zr0.2Ti0.8)0.96O3, Pb0.91La0.09(Zr0.65Ti0.35)0.98O3, and Pb0.85La0.15Ti0.96O3 films grown on platinized silicon substrates using a sol-gel method and on (0001) sapphire using a radio-frequency sputtering method. Using a parametric optical constant model, we estimate the dielectric functions (ϵ) of the perovskite oxide thin films. Taking the second derivative of the fitted layer dielectric functions and using the standard critical-point model, we determine the parameters of the critical points. In the second derivative spectra, the lowest band-gap energy peak near 4eV is fitted as a double peak for annealed PZTs due to the perovskite phase. As-grown PZTs have mainly pyrochlore phase and the lowest band-gap peak is fitted as a single peak. We also examine the effect of dopants La and Nb, which substitute at Pb and Zr (Ti) sites, respectively. We found three band gaps E...