Showing papers on "Lead zirconate titanate published in 2007"
TL;DR: Electroelectric arrays of lead zirconate titanate have been reported on Pt nanowire interconnects and nanorings with 5-nanometer diameters and electron emission from ferroelectrics yields cheap, high-power microwave devices and miniature x-ray and neutron sources.
Abstract: Long viewed as a topic in classical physics, ferroelectricity can be described by a quantum mechanical ab initio theory. Thin-film nanoscale device structures integrated onto Si chips have made inroads into the semiconductor industry. Recent prototype applications include ultrafast switching, cheap room-temperature magnetic-field detectors, piezoelectric nanotubes for microfluidic systems, electrocaloric coolers for computers, phased-array radar, and three-dimensional trenched capacitors for dynamic random access memories. Terabit-per-square-inch ferroelectric arrays of lead zirconate titanate have been reported on Pt nanowire interconnects and nanorings with 5-nanometer diameters. Finally, electron emission from ferroelectrics yields cheap, high-power microwave devices and miniature x-ray and neutron sources.
2,495 citations
TL;DR: In this paper, the intrinsic electrocaloric coefficient at electric fields sufficient to destroy the discontinuous ferroelectric phase transition results in an adiabatic temperature change of 8K that agrees closely with the giant value of 12K recently observed experimentally for lead zirconate titanate thin films.
Abstract: Monodomain contributions to the electrocaloric effect in mechanically free (bulk) and laterally clamped (thin film) BaTiO3 are computed using a thermodynamic analysis. The authors show that the intrinsic electrocaloric coefficient at electric fields sufficient to destroy the discontinuous ferroelectric phase transition results in an adiabatic temperature change of 8K that agrees closely with the giant value of 12K recently observed experimentally for lead zirconate titanate thin films [A. S. Mischenko et al., Science 311, 1270 (2006)]. Perfect lateral clamping transforms the discontinuous transition into a continuous transition, which decreases the magnitude of the electrocaloric effect by 20% but reduces its sensitivity to temperature.
194 citations
TL;DR: In this paper, the authors used resonance methods to determine the variation of all the independent piezoelectric, elastic, and dielectric material coefficients, as well as the corresponding electromechanical coupling factors, of soft and hard doped PZT ceramics with compositions near the morphotropic phase boundary, as a function of temperature ranging between −165 and 195°C.
Abstract: We have used resonance methods to determine the variation of all the independent piezoelectric, elastic, and dielectric material coefficients, as well as the corresponding electromechanical coupling factors, of soft and hard doped piezoelectric lead zirconate titanate (PZT) ceramics with compositions near the morphotropic phase boundary, as a function of temperature ranging between −165 and 195°C. The material coefficients were obtained by analyzing the fundamental resonance of the impedance or admittance spectra as a function of frequency for several sample resonance geometries. The piezoelectric coefficients d33, −d31, and d15, as well as the dielectric permittivity coefficients e11T and e33T, generally increased with temperature for both soft and hard PZT samples. However, the elastic compliance coefficients s11E, −s12E, s33E, and s55E exhibited abnormal variations seen as broad peaks over parts of the tested temperature range. Additionally, thermal hystereses were observed in all the studied material ...
154 citations
TL;DR: Pb(Zrx,TiOx,Ti1−x)O3 thin films of homogeneous composition were synthesized by means of a modified sol-gel route on Pt(111)∕TiOx∕SiO2 ∕Si substrates.
Abstract: Pb(Zrx,Ti1−x)O3 thin films of homogeneous composition were synthesized by means of a modified sol-gel route on Pt(111)∕TiOx∕SiO2∕Si substrates The gradient in B-site composition as obtained by standard routes could be lowered, reducing Zr concentration fluctuations form ±12to±25at% The 2μm thick, dense and crack-free films exhibited a {100}-texture index of 984% Grain diameters increased by 50% Dielectric and piezoelectric properties were remarkably improved The relative dielectric constant e33,f was obtained as 1620, and the remanent transverse piezoelectric coefficient e31,f was measured as −177Cm2
148 citations
TL;DR: In this article, the spectral properties of the short-circuit photocurrent (SC-PHC) in the 200-800nm wavelength domain were investigated and it was shown that the sign and magnitude of the signal depend on the internal bias and on the spontaneous polarization direction and value.
Abstract: Photovoltaic properties of the metal-ferroelectric-metal structures, having SrRuO3 metal oxide electrodes and Pb(Zr,Ti)O3 (PZT) as ferroelectric layer, are investigated by the short-circuit photocurrent (SC-PHC) in the 200–800nm wavelength domain. The band-gap dependence on the Zr content was determined from the spectral distribution of the SC-PHC signal. It was found that the band-gap value increases linearly with the Zr content, from about 3.9eV to about 4.4eV. It is shown that the sign and the magnitude of the signal depend on the internal bias and on the spontaneous polarization direction and value. The photocurrent describes a hysteresis loop similar to that of the ferroelectric polarization and can be used as a nondestructive readout of the nonvolatile memories based on PZT films. The existence of a significant SC-PHC signal at wavelengths corresponding to subgap energies is attributed to the presence of charged, deep levels in the forbidden band. It is also shown that the epitaxial PZT films have t...
141 citations
TL;DR: In this paper, a combination of ex situ and in situ transmission electron microscopy and high resolution x-ray diffraction revealed that the extrinsic piezoelectric effect in morphotropic PZT is closely connected to the existence of nanodomains.
Abstract: The outstanding piezoelectric properties of lead zirconate titanate (PZT) ceramics with compositions close to the morphotropic phase boundary of the quasibinary phase diagram of lead zirconate and lead titanate are still under debate. A combination of ex situ and in situ transmission electron microscopy and high resolution x-ray diffraction revealed that the extrinsic piezoelectric effect in morphotropic PZT is closely connected to the existence of nanodomains. The in situ transmission electron microscopy investigations with applied electric field show that mainly the nanodomains respond to the electric field while the microdomain structure does not change noticeably in our experiments.
132 citations
TL;DR: In this paper, the piezoelectric, dielectric and ferroelectric properties of porous PZT ceramics were investigated as a function of pore shape and porosity.
Abstract: Porous lead zirconate titanate (PZT 95/5) ferroelectric ceramics were prepared by sintering compacts consisting of PZT and pore formers. The piezoelectric, dielectric and ferroelectric properties of porous PZT ceramics were investigated as a function of pore shape and porosity. Piezoelectric coefficient ( d 33 ), dielectric constant ( ɛ 33 ) and remnant polarization ( P r ) decreased with an increase in porosity, and the porous PZT ceramics with spherical pores exhibited better properties than that with irregular pores. Furthermore, the electrical conductivities of PZT ceramics were investigated to explain the phenomena that porous PZT ceramics exhibited lower dielectric loss (tan δ ) than dense PZT ceramics in the temperature range from 250 to 500 °C.
131 citations
TL;DR: In this paper, the defect structure of aliovalent transition-metal and rare-earth functional centers in ferroelectric perovskite oxides is characterized by means of multifrequency electron paramagnetic resonance spectroscopy, assisted by density-functional theory calculations.
Abstract: The defect structure of aliovalent transition-metal and rare-earth functional centers in ferroelectric perovskite oxides is characterized by means of multifrequency electron paramagnetic resonance spectroscopy, assisted by density-functional theory calculations. The review is mainly focused on lead zirconate titanate (Pb[Zr
x
Ti1−x
]O3, PZT) compounds. However, where available also results on ferroelectric ’lead-free’ compounds are discussed. The results include the formation of charged $({\rm Fe}'_{\rm Zr,Ti}-V_{\rm O}^{\bullet \bullet})^{\bullet}$
defect dipoles, causing internal bias fields, multivalence manganese centers, acceptor-type copper functional centers creating isolated oxygen vacancies that promote ionic conductivity, as well as ${\rm Gd}_{\rm Pb}^{\bullet}$
donor-type centers. Moreover, the impact of the defect structure on macroscopic material properties is discussed.
126 citations
TL;DR: In this article, a model for low-frequency magnetoelectric (ME) effects in nanobilayers, nanopillars, and nanowires of nickel ferrite (NFO) and lead zirconate titanate (PZT) on MgO substrates or templates was presented.
Abstract: A model is presented for low-frequency magnetoelectric (ME) effects in nanobilayers, nanopillars, and nanowires of nickel ferrite (NFO) and lead zirconate titanate (PZT) on MgO substrates or templates. The clamping effect of the substrate for the bilayer and pillars and of the template for the wires have been considered in determining the ME voltage coefficient. The ME interactions have been found to be the strongest for field orientations corresponding to minimum demagnetizing fields, i.e., in-plane fields for bilayers and axial fields for pillars and wires. It is shown that the coupling strength decreases with increasing substrate clamping. For increasing volume of MgO substrate in a bilayer, (i) the ME coefficient drops exponentially and (ii) the PZT volume required for maximum ME effects increases. For nanopillars of NFO in PZT matrix on MgO, the substrate pinning effects are negligible only when the length of the pillar is much greater than its radius. In the case of NFO-PZT nanowires grown on a MgO nanowire template, the ME coefficient is predicted to decrease from a maximum to approaching zero as the radius of the template layer is increased.
109 citations
TL;DR: In this article, a lead-free superthin buzzer disk has been prepared by using piezoceramic membrane with x = 0.20 between two morphotropic phase boundaries.
Abstract: Lead-free (K0.44Na0.52Li0.04)(Nb0.96−xTaxSb0.04)O3 piezoelectric ceramics have been synthesized by conventional solid state sintering process. Two morphotropic phase boundaries (MPBs) respectively corresponding to the orthorhombic to tetragonal and tetragonal to pseudocubic phases are observed with increasing x. The ceramics with x=0.20 between the two MPBs show significantly enhanced electrical properties, which are as follows: piezoelectric constant d33=252pC∕N, planar coupling coefficient kp=0.42, dielectric constant er=1503, and dielectric loss tanδ=0.025, and they show good stability. Lead-free superthin buzzer disks have been prepared by using piezoceramic membrane with x=0.20. (K0.44Na0.52Li0.04)(Nb0.96−xTaxSb0.04)O3 ceramics are very promising as lead-free replacements for lead zirconate titanate.
108 citations
TL;DR: The photochemical growth of silver nanoparticles on the negative domains of lead zirconate titanate thin films is reported and is explained in terms of changed band bending due to the excitation of electrons into the conduction band, the rate of decay to the ground state, and dimensions of the ferroelectric film.
Abstract: The photochemical growth of silver nanoparticles on the negative domains of lead zirconate titanate thin films is reported. A sample of highly [100] orientated lead zirconate titanate, with a ratio of 30:70, that was 65-70 nm thick grown on Pt-coated MgO was poled by use of piezoresponse force microscopy to produce defined regions of surface positive and negative polarization. A comparison between the growth of silver nanoparticles on the surface of the lead zirconate titanate when illuminated with two sources of super band gap UV is given. In both cases the wavelength of illumination leads to growth on the positive domains but only illumination with a Honle H lamp, with a high photon output over 250-200 nm, caused significant growth of silver nanoparticles on the negative domain. The deposition on the negative domain is explained in terms of changed band bending due to the excitation of electrons into the conduction band, the rate of decay to the ground state, and dimensions of the ferroelectric film. The rate of deposition of silver nanoparticles on the negative domains is approximately half that on the positive domains.
TL;DR: In this article, a degradation of the ferroelectric material occurs both under unipolar cycling as well as DC loads, and a mechanism for unipolar fatigue is suggested to explain the observed changes in material properties with cyclic loading.
Abstract: In actuator applications, a degradation of the ferroelectric material occurs both under unipolar cycling as well as DC loads. The developing material state is characterized by measurements of large and small signal unipolar as well as bipolar hysteresis loops. While the unipolar loops indicate a small decrease in strain and polarization amplitudes, the bipolar loops unveil the development of an offset field, an offset polarization, and an asymmetry in the hysteresis of strain and dielectric constant. A mechanism for unipolar fatigue is suggested to explain the observed changes in material properties with cyclic loading.
TL;DR: In this article, a Taylor cone is formed by applying a strong electrostatic field to a capillary connected with a reservoir containing a polymer solution or melt, and the solvent begins to evaporate immediately after the jet is formed.
Abstract: Electrospinning technique is becoming increasingly13; popular for the preparation of nanofibers [1x2013;5]. The13; process involves the application of a strong electrostatic13; field to a capillary connected with a reservoir13; containing a polymer solution or melt. Under the13; influence of the electrostatic field, a pendant droplet of13; the polymer solution at the capillary tip is deformed13; into a conical shape (Taylor cone). If the voltage surpasses13; a threshold value, electrostatic forces overcome13; the surface tension, and a fine charged jet is ejected.13; The jet moves towards a ground plate, which acts as a13; counter electrode. The solvent begins to evaporate13; immediately after the jet is formed. The result is the13; deposition of nanofibers on a substrate located above13; the counter electrode. Initially, this technique was used13; for the preparation of polymer nanofibers [6x2013;9]. In13; recent years; this technique has been used for the13; preparation of metal oxide/ceramic nanofibers such as13; silica, zirconia, titania, nickel oxide, barium titanate,13; lead zirconate titanate and other oxide materials [10x2013;13; 30]. The nanofibers formed could be aligned (parallel13; and cross patterns) when an insulated cylinder attached13; to the axel of a DC motor is used as the substrate [31].13; Xia et al. [32] prepared polymeric and ceramic nanofibers13; as axially aligned arrays by the use of a collector13; consisting of two pieces of electrically conductive13; substrate separated by a gap. Katta et al. used copper13; wires spaced evenly in the form of a circular drum as a13; collector of the electro spun nanofibers
TL;DR: In this paper, a surface micromachined RF microelectromechanical switch that uses piezoelectric actuators is presented, which exhibits better than 20dB isolation from dc up to 65 GHz and as large as 70 dB below 1 GHz.
Abstract: This paper presents results on a surface micromachined RF microelectromechanical switch that uses piezoelectric actuators. The switch uses solution chemistry-derived lead zirconate titanate thin films spun deposited onto a high-resistivity silicon substrate with coplanar waveguide transmission lines. Actuation voltages, applied via circuits independent of the RF circuitry, average less than 10 V, with switch operation demonstrated as low as 2 V. The series switch exhibits better than 20-dB isolation from dc up to 65 GHz and as large as 70 dB below 1 GHz. In the closed state, the switch has an insertion loss less than 1 dB up to 40 GHz, limited in this demonstration by substrate losses from the elastic layer used to stress control the piezoelectric actuators. Switching speeds for the different designs are in the range of 40-60 ms. Thermal sensitivity measurements show no change in isolation observed for temperatures up to 125degC. However, an increase in actuation voltage is required at elevated temperatures.
TL;DR: In this paper, the electrical and acoustic properties of porous PZT ceramics were investigated, and the electrical properties were associated with porosity and the interconnection of pores, but only slightly associated with the shape of pores.
TL;DR: In this article, the effects of temperature on poling strain and strain under unipolar cycling at electric fields of 2.5 kV mm−1 have been investigated for morphotropic donor doped lead zirconate titanate (PZT) with various Zr/Ti ratios between 20 and 160 °C.
TL;DR: In this article, the effects of PZT on dielectric and piezoelectric properties of the composites were investigated, and the results showed that the effects were most significant at two stages, first at 30% pZT volume content (14 pC/N) and then at very high PZTs content (90% by volume) where d 33 value reached 43 pC /N.
TL;DR: In this article, the residual tensile stresses of three sol-gel derived Pb(Zr0.53Ti0.47)O3 thin film specimens of different thicknesses integrated onto Pt∕Ti∕SiO2‖Si substrates are investigated to delineate the influence of residual stress on the strain-field response characteristics from other thickness related effects.
Abstract: Piezoelectric properties of three sol-gel derived Pb(Zr0.53Ti0.47)O3 thin film specimens of different thicknesses integrated onto Pt∕Ti∕SiO2‖Si substrates are investigated to delineate the influence of residual stress on the strain-field response characteristics from other thickness related effects. Residual tensile stresses are determined from wafer curvature measurements for films ranging in thickness from 190to500nm. Field-induced strains are measured interferometrically for each film under either a large ac driving voltage or a small ac ripple applied over a range of dc biases. Higher residual stresses decrease measured piezoelectric response, while thickness variations with no accompanying change in residual stress state produce little change in strain-field behavior. The diminished performance associated with high residual stresses is attributed to reductions in both linear and nonlinear contributions, including decreased polarization switching and domain motion.
TL;DR: In this article, a bipolar cycling of lead zirconate titanate ceramics can lead to massive material damage in regions close to the electrode, which can be identified by color changes, and the microstructure in this region shows signs of interface melting.
Abstract: Bipolar cycling of lead zirconate titanate ceramics can lead to massive material damage in regions close to the electrode. The damaged region can be identified by color changes, and the microstructure in this region shows signs of interface melting. This damaged region can screen the sample volume from the applied voltages and reduced fields are applied to the undamaged part of the sample. This has two effects. The first one is that the bulk is effectively subjected to smaller fields, but the measured parameters are assigned to the applied field, yielding apparent fatigue curves. The second effect is that with further cycling, field screening protects the bulk of the sample from fatigue due to the reduced effective fields. If the damaged region is mechanically removed and the ferroelectric hystereses are measured again, nearly unfatigued parameters are obtained.
TL;DR: In this article, the effect of different pore formers and their content on the microstructure and piezoelectric properties of PZT ceramics was investigated.
TL;DR: In this article, the temperature scaling of the dynamic hysteresis in soft ferroelectric bulk ceramic was investigated and the power-law temperature scaling relations were obtained for hystersis area ⟩ and remnant polarization Pr.
Abstract: The temperature scaling of the dynamic hysteresis was investigated in soft ferroelectric bulk ceramic. The power-law temperature scaling relations were obtained for hystersis area ⟨A⟩ and remnant polarization Pr, while the coercivity EC was found to scale linearly with temperature T. The three temperature scaling relations were also field dependent. At fixed field amplitude E0, the scaling relations take the forms of ⟨A⟩∝T−1.1024, Pr∝T−1.2322, and (EC0−EC)∝T. Furthermore, the product of Pr and EC also provides the same scaling law on the T dependence in comparison with ⟨A⟩.
TL;DR: In this article, a polymer assisted solvothermal technique was used to grow a monocrystalline lead zirconate titanate nanowires, and X-ray and electron diffraction confirmed tetragonal perovskite structure and a [001] orientation along the wire axis.
Abstract: Monocrystalline lead zirconate titanate nanowires were grown by a polymer assisted solvothermal technique. X-ray and electron diffractions confirmed tetragonal perovskite structure and a [001] orientation along the wire axis, respectively. Raman scattering was used to analyze the structure and composition of single wires. Ferroelectric/ferroelastic domain walls were imaged by transmission electron microscopy, showing some domains with polarization directions along the wire axis and some perpendicular to it. The domain walls disappeared upon heating above the ferroelectric phase transition at 460°C. Ferroelectric switching, as well as piezoelectric activity and hysteresis, were shown locally using piezoelectric force microscopy.
TL;DR: In this paper, the authors investigated the strain behavior of morphotropic, 1La2Sr-doped lead zirconate titanate and found that the electric field induced strain (S-E characteristic) in the high field range for morphotropic materials having different Zr∕Ti ratios.
Abstract: The strain behavior of morphotropic, 1La2Sr-doped lead zirconate titanate was investigated. Particular attention was paid to the electric field induced strain (S-E characteristic) in the high field range for morphotropic materials having different Zr∕Ti ratios. Unipolar electrical cycles with maximum fields between 1 and 3kV∕mm were applied to the poled materials under load-free conditions. Strain curves were recorded and the data were evaluated with respect to field dependence of strain and strain hysteresis. Nonlinearity of strain was detected for all materials. Depending on the composition, marked differences were found with respect to the types of nonlinearity. The corresponding data on strain hysteresis indicate that the nonlinearity was due to a loss generating strain mechanism. Therefore the nonlinearity was attributed to domain switching. A phenomenological model is suggested, which is based on the assumptions of a distribution of domain switching over a field range. This field range is characteri...
TL;DR: In this article, the elasticity solution of PZT generated wave propagation is derived in terms of the wave reflection and transmission matrices, and the viscoelasticity solution is obtained directly from the elastic solution.
Abstract: Despite various successful applications of lead zirconate titanate (PZT) material for structural health monitoring (SHM), the fundamental research work of determining the PZT sensing region is still needed. Among a variety of issues in relation to the PZT sensing region, this paper focuses on one of the most important factors, the material and structural damping. The elasticity solution of PZT generated wave propagation is first derived in terms of the wave reflection and transmission matrices. Subsequently, based on the corresponding principle, the viscoelasticity solution is obtained directly from the elasticity solution. Finally, the output voltage of the PZT sensor is calculated according to the PZT–structure interaction effect. In the experiment, an aluminum beam specimen bonded with PZT actuators as well as PZT sensors is tested. The output voltages of sensors are compared with the theoretical predictions to verify the developed model and to determine the reliable sensing region of PZT transducers.
TL;DR: The scaling relation of ferroelectric hysteresis area against frequency f and field amplitude E 0 for the saturated loops of the hard lead zirconate titanate bulk ceramic takes the form of ⟨A⟩∝f−0.28E00.89, while for the minor loops, the scaling relations are similar to those of its soft counterpart as mentioned in this paper.
Abstract: The scaling relation of ferroelectric hysteresis area ⟨A⟩ against frequency f and field amplitude E0 for the saturated loops of the hard lead zirconate titanate bulk ceramic takes the form of ⟨A⟩∝f−0.28E00.89, while that for the minor loops takes the form of ⟨A⟩∝f−0.43E03.19. In both cases, the scaling relations are similar to those of its soft counterpart. This indicates that the dynamic behaviors and scaling relations in bulk ceramics are mainly governed by the domain states and structures, while the distinct types of complex defects contribute mainly to the difference in the coercive field observed in hard and soft ceramics.
TL;DR: In this article, the authors discuss the microscopic origin of CPEs in the general literature, often being attributed to fractal dimensionality of the capacitor, near-electrode gradients in the dielectric, fringing fields near the electrode perimeter or a distribution of relaxation times.
Abstract: Several commercial high density ferroelectric random access memory (FeRAM) devices utilize stacks of submicron lead zirconate-titanate (PZT) capacitors. The low-field electrical characteristics of these capacitors display a specific frequency dependence which is best represented by a constant phase element (CPE) in the equivalent circuit diagram. The microscopic origin of such CPEs in the general literature is still of some debate, often being attributed to fractal dimensionality of the capacitor, near-electrode gradients in the dielectric, fringing fields near the electrode perimeter or, more generally, a distribution of relaxation times. We discuss these possibilities.
TL;DR: In this article, the inverse magnetoelectric (ME) effects in lead zirconate titanate (PZT) and Ni trilayers were measured using a pickup coil wound around the sample to measure the ME voltage due to the change in the magnetic induction in Ni.
Abstract: Measurements of inverse magnetoelectric (ME) effects in lead zirconate titanate (PZT)–Ni–PZT trilayers are reported. Traditional ME measurements involve the electrical response of a composite subjected to an alternating current (ac) magnetic field. In the case of an “inverse ME effect,” one measures the variation in the magnetic induction due to an external ac electric field applied to PZT. A pickup coil wound around the sample is used to measure the ME voltage due to the change in the magnetic induction in Ni. The measured static magnetic-field dependence of ME voltage has been attributed to the variation in the piezomagnetic coefficient for Ni. The frequency dependence of the ME voltage shows a resonance character due to radial acoustic modes in PZT. Theoretical estimates of ME susceptibility are in excellent agreement with values determined from data on induced voltage.
TL;DR: In this article, the authors measured non-180° domain switching and crystallographic lattice strains in situ around a crack tip in a soft tetragonal lead zirconate titanate ceramic.
TL;DR: In this paper, a combination of vapor growth carbon nanofibers (CNF), lead zirconate titanate piezoelectric (PZT) particles, as well as the combination of these two two were added in an epoxy resin (EP), and their influence on the mechanical quasi-static properties was investigated.
Abstract: Vapor growth carbon nanofibers (CNF), lead zirconate titanate piezoelectric (PZT) particles, as well as a combination of these two were added in an epoxy resin (EP), and their influence on the mechanical quasi-static properties was investigated. Moreover, the prepared samples were characterised by dynamic thermal mechanical analysis, and optical and scanning electron microscopy. Enhancement of the mechanical properties was observed by the addition of the CNF. The uncured mixtures were also used as matrix material for manufacturing unidirectional carbon fiber reinforced laminates.
TL;DR: In this paper, the dielectric constants of the composites were found to be 139, 176 and 290 for composites containing 40, 50% and 60% PZT respectively.