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Zirconate Titanate (zirconate + titanate)
Kinds of Zirconate Titanate Selected AbstractsStrength Properties of Poled Lead Zirconate Titanate Subjected to Biaxial Flexural Loading in High Electric FieldJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010Hong Wang The mechanical strength of poled lead zirconate titanate (PZT) has been studied using ball-on-ring (BoR) biaxial flexure tests with a high electric field applied concurrently. Both the as-received and the aged PZT specimens were tested. The Weibull plot and a 95% confidence ratio ring were used to characterize the responses of mechanical strength under various electric loading conditions. A fractographical study has been conducted at the same time, and the fracture origins or strength-limiting flaws of tested PZT specimens have been identified and characterized accordingly. The fracture toughness was further estimated to correlate with the obtained fracture stresses and flaws. It has been observed that electric field affects the mechanical strength of poled PZT, and the degree of the effect depends on the sign and magnitude of the applied electric field. Within the examined electric field range of ,3 to +3 times the coercive field, an increasing electric field resulted in a rapid strength decrease and a sharp increase with the turning point around the negative coercive field. Surface-located volume-distributed flaws were identified to be strength limiting for this PZT material. Variations of the mechanical strength with the electric field were believed to be related to the domain switching and amount of switchable domains. An aging effect on the mechanical strength of poled PZT could be significant, especially in the OC condition. These results and observations have the potential to serve probabilistic reliability analysis and design optimization of multilayer PZT piezo actuators. [source] Domain Switching Under Cyclic Mechanical Loading in Lead Zirconate TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2006Soodkhet Pojprapai (Imlao) The domain-switching behavior of lead zirconate titanate (PZT) during mechanical cyclic loading between 10 and 150 MPa was investigated by in situ time-of-flight neutron diffraction. The domain-switching behavior was represented by a change of the pole density distribution during cycling. With increasing number of cycles, domain switching becomes saturated, correlating with a decrease in the rate of remnant strain accumulation in the stress,strain curve. Moreover, a relationship was demonstrated between the macroscopic strain and that developed from ferroelastic domain switching. The contribution of ferroelastic strain to the macroscopic strain was calculated from an orientation average of the domain switching distributions and the c/a ratio. The results show that nearly 80% of macroscopic strain arises from ferroelastic domain switching during mechanical cyclic loading. [source] Subcritical Crack Growth in Lead Zirconate TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2004William S. Oates Subcritical crack growth in terms of velocity,stress intensity factor (v,K) curves in lead zirconate titanate (PZT) were experimentally characterized on poled and unpoled compact tension specimens. The poled specimens were tested under open- and short-circuit electrical boundary conditions, which resulted in an increase in fracture toughness by 0.2 MPa·m1/2 for the accessible velocity range (v= 10,9 to 10,4 m/s) in the open-circuit case. Subcritical crack growth of unpoled specimens was obtained under ambient (relative humidity = 35%) and dry (relative humidity , 0.02%) conditions over a regime in stress intensity factor of 0.5 MPa·m1/2. [source] Crack,Tip Toughness of a Soft Lead Zirconate TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2003Alain B. Kounga Njiwa Crack,opening displacement (COD) measurements were performed on a commercial lead zirconate titanate (PZT). The intrinsic fracture toughness (or crack,tip toughness) of this material was determined using a new evaluation procedure, which takes into account the near,tip CODs and complete crack profile CODs. The crack,tip toughness KI0 was determined from an extrapolation of COD data obtained at various loading stages, thus avoiding the complications caused by subcritical crack growth in PZT. Results for plane strain and plane stress condition are presented. [source] Fabrication of Optically Transparent Lead Lanthanum Zirconate Titanate ((Pb,La)(Zr,Ti)O3) Ceramics by a Three-Stage-Atmosphere-Sintering TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2002Yoshiyuki Abe An easy technique has been developed to fabricate optically transparent lanthanum-modified lead zirconate titanate (PLZT) ceramics. This technique consists of three stages: (1) sintering in an oxygen atmosphere, (2) elimination of pores in a carbon dioxide atmosphere, and (3) elimination of oxygen vacancies in an oxygen atmosphere. The carbon dioxide atmosphere enhances the diffusion of oxygen from the pores to outside the sintered body. The experimental results reveal that use of a carbon dioxide atmosphere effectively decreases residual pores and improves optical transmittance. From commercially available raw powders, an optical transmittance of 51% (wavelength of 550 nm) can be achieved for 0.7 mm thick polished PLZT9/65/35 ceramics using a carbon dioxide atmosphere, whereas the value is only 34% without a carbon dioxide atmosphere. The advantage of this technique is that PLZT ceramics having high optical quality can be obtained using conventional sintering tools. [source] Thermoplastic Extrusion to Highly-Loaded Thin Green Fibres Containing Pb(Zr,Ti)O3,ADVANCED ENGINEERING MATERIALS, Issue 5 2005J. Heiber Because of their piezoelectric properties lead zirconate titanate (PZT) fibres are used in several electronic applications. Such fibres can be produced by extrusion. Therefore the extrusion behaviour of highly loaded thermoplastic feedstocks (PZT-polymer compound) has been investigated depending on the surfactant concentration and the powder preparation method. After sintering butterfly curves were measured for single fibres. [source] Quantitative structural damage detection using high-frequency piezoelectric signatures via the reverberation matrix methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2007W. Yan Abstract High-frequency structural analysis so far has been a major issue in dynamic analysis, for which many conventional methods such as finite element method and transfer matrix method are unable to perform well. Since the electromechanical impedance technique for structural health monitoring (SHM) operates at very high frequencies, the reverberation matrix method (RMM), which was just developed a few years ago, is employed to study dynamics of the monitored structures, which are bonded with piezoelectric lead zirconate titanate (PZT) patches. A piecewisely homogeneous Euler,Bernoulli beam model is introduced to approximate the non-homogeneous beam and only one-dimensional axial vibration of PZT wafers is considered. The imperfect interfacial bonding between PZT patches and the host beam is investigated based on a shear lag model. Using a hybrid technique combining electromechanical impedance method and RMM, an analytical expression of impedance (or admittance) related to the response of the coupled model of PZT patch-bonding layer-host beam system is derived for SHM. The proposed method is examined by comparing with other theoretical methods as well as by means of a test on an intelligent system using a steel beam with two symmetrically installed PZT wafers. It could be further applied to predicting the dynamics of monitored Timoshenko beams, continuous beams, and framed structures as well. Copyright © 2006 John Wiley & Sons, Ltd. [source] Strength Properties of Poled Lead Zirconate Titanate Subjected to Biaxial Flexural Loading in High Electric FieldJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010Hong Wang The mechanical strength of poled lead zirconate titanate (PZT) has been studied using ball-on-ring (BoR) biaxial flexure tests with a high electric field applied concurrently. Both the as-received and the aged PZT specimens were tested. The Weibull plot and a 95% confidence ratio ring were used to characterize the responses of mechanical strength under various electric loading conditions. A fractographical study has been conducted at the same time, and the fracture origins or strength-limiting flaws of tested PZT specimens have been identified and characterized accordingly. The fracture toughness was further estimated to correlate with the obtained fracture stresses and flaws. It has been observed that electric field affects the mechanical strength of poled PZT, and the degree of the effect depends on the sign and magnitude of the applied electric field. Within the examined electric field range of ,3 to +3 times the coercive field, an increasing electric field resulted in a rapid strength decrease and a sharp increase with the turning point around the negative coercive field. Surface-located volume-distributed flaws were identified to be strength limiting for this PZT material. Variations of the mechanical strength with the electric field were believed to be related to the domain switching and amount of switchable domains. An aging effect on the mechanical strength of poled PZT could be significant, especially in the OC condition. These results and observations have the potential to serve probabilistic reliability analysis and design optimization of multilayer PZT piezo actuators. [source] Comparison of the Temperature-Dependent Ferroelastic Behavior of Hard and Soft Lead Zirconate Titanate CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010Mie Marsilius The ferroelastic properties of a hard acceptor-doped lead zirconate titanate (PZT) ceramic are investigated between room temperature and 300°C. Comparison with a soft PZT shows that acceptor doping has a stronger influence on mechanically induced domain switching than on switching caused by electric fields. A quantitative analysis of spontaneous and remanent strain and polarization indicates that poling in the soft material is dominated by 180° domain processes, while non-180° processes dominate the strain behavior. If the mechanical load exceeds a threshold level, the "hardening" effect of the acceptor doping vanishes, and hard and soft materials behave identically. The results are discussed based on the defect dipole model and the charge drift model for hardening and aging in acceptor-doped ferroelectric ceramics. [source] Processing Conditions and Aging Effect on the Morphology of PZT Electrospun Nanofibers, and Dielectric Properties of the Resulting 3,3 PZT/Polymer CompositeJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2009Ebru Mensur Alkoy Lead zirconate titanate (PZT) nanofibers are obtained by electrospinning a sol,gel based solution and polyvinyl pyrrolidone (PVP) polymer, and by subsequent sintering of the electrospun precursor fibers. The average diameter of the precursor PZT/PVP green fibers has increased with the aging of the precursor solution along with an increase in the viscosity. Bead-free uniform green PZT/PVP fibers were collected at about an ,230 nm average fiber diameter using a 28 wt% PVP ratio solution with a viscosity of 290 mPa. Shrinkage of 40% was recorded on the fiber diameter after sintering. The X-ray diffraction pattern of the annealed PZT fibers exhibits no preferred orientation and a perovskite phase. Preparation of 3,3 nanocomposites by the infusion of polyvinylester into the nanofiber mat facilitates successful handling of the fragile mats and enables measurements of the dielectric properties. The dielectric constant of the PZT/polyvinylester nanocomposite of about 10% fiber volume fraction was found to be fairly stable and vary from 72 to 62 within the measurement range. The dielectric loss of the composite is below 0.08 at low frequencies and reaches a stable value of 0.04 for most of the measured frequencies. [source] Fatigue of Lead Zirconate Titanate Ceramics II: Sesquipolar LoadingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2007Nina Balke Piezoelectric actuators generally are driven with unipolar electric load cycles. Although the obtainable strain is increased by small excursions into the negative field regime, this type of load cycle is rarely considered, as its long-time reliability has been questioned. Here, we investigate the degradation of lead zirconate titanate during cycling between high positive and low negative electric fields. Measurements of the large and small signal parameters are used to quantify changes of the material. The fatigue behavior shifts from one best described with existing models of unipolar fatigue to bipolar-like fatigue with increasing field amplitude. [source] Domain Switching Under Cyclic Mechanical Loading in Lead Zirconate TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2006Soodkhet Pojprapai (Imlao) The domain-switching behavior of lead zirconate titanate (PZT) during mechanical cyclic loading between 10 and 150 MPa was investigated by in situ time-of-flight neutron diffraction. The domain-switching behavior was represented by a change of the pole density distribution during cycling. With increasing number of cycles, domain switching becomes saturated, correlating with a decrease in the rate of remnant strain accumulation in the stress,strain curve. Moreover, a relationship was demonstrated between the macroscopic strain and that developed from ferroelastic domain switching. The contribution of ferroelastic strain to the macroscopic strain was calculated from an orientation average of the domain switching distributions and the c/a ratio. The results show that nearly 80% of macroscopic strain arises from ferroelastic domain switching during mechanical cyclic loading. [source] Piezoelectric Multilayer Ceramic/Polymer Composite Transducer with 2,2 ConnectivityJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2006Chang-Bun Yoon A multilayer piezoelectric ceramic/polymer composite with 2,2 connectivity was fabricated by thermoplastic green machining after co-extrusion. The multilayer ceramic body was composed of piezoelectrically active lead zirconate titanate (PZN),lead zinc niobate (PZN)-lead zirconate titanate (PZT) layers and electrically conducting PZN,PZT/Ag layers. After co-extruding the thermoplastic body, which consisted of five piezoelectric layers interspersed with four conducting layers, it was computer numeric-controlled machined to create periodic channels within it. Following binder burnout and sintering, an 18 vol% array of 190 ,m thin PZT slabs with a channel size of 880 ,m was fabricated. The channels were filled with epoxy in order to fabricate a PZN,PZT/epoxy composite with 2,2 connectivity. The piezoelectric coefficient (effective d33) and hydrostatic figure of merit (dh×gh) of the PZN,PZT/epoxy composite were 1200 pC/N and 20 130 × 10,15 m2/N, respectively. These excellent piezoelectric characteristics as well as the relatively simple fabrication procedure will contribute in widening the application range of the piezoelectric transducers. [source] Ordered Ceramic Microstructures from Butterfly Bio-templateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2006Bo Li Ordered lead lanthanum zirconate titanate (PLZT) structures with micrometer and submicrometer periods were created by an impressing sol,gel process, in which PLZT was used as the ceramic precursor and various butterfly wings were used as biological templates. It is a simple, inexpensive, and lithography-free method for fabricating two-dimensional-ordered microstructures using natural biological templates, which can be used to study the periodic submicrometer dimension effect and photonic bandgap property of functional ceramics. [source] Subcritical Crack Growth in Lead Zirconate TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2004William S. Oates Subcritical crack growth in terms of velocity,stress intensity factor (v,K) curves in lead zirconate titanate (PZT) were experimentally characterized on poled and unpoled compact tension specimens. The poled specimens were tested under open- and short-circuit electrical boundary conditions, which resulted in an increase in fracture toughness by 0.2 MPa·m1/2 for the accessible velocity range (v= 10,9 to 10,4 m/s) in the open-circuit case. Subcritical crack growth of unpoled specimens was obtained under ambient (relative humidity = 35%) and dry (relative humidity , 0.02%) conditions over a regime in stress intensity factor of 0.5 MPa·m1/2. [source] Rapid Prototyping of Piezoelectric Ceramics via Selective Laser Sintering and GelcastingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004Dong Guo This article presents a new lost mold rapid prototyping method which combines selective laser sintering (SLS) and gelcasting techniques for fabricating piezoelectric ceramics. SLS was used to fabricate sacrificial molds of the desired structure of the ceramic part. Then aqueous PZT (lead zirconate titanate) suspension was cast in the mold and solidified in situ through formation of a three-dimensional network gel. Because the polymer mold can be easily removed at the initial stage of sintering and the gelcast PZT body has a high green strength, the desired geometry of the PZT part can be completely retained after sintering of the ceramics. Complex-shaped PZT parts were successfully fabricated after using concentrated PZT suspension with low viscosity. Densities and electrical properties, such as the d33, the relative permittivity ,, the dielectric loss tg, and the electromechanical coupling factor Kp of the gelcast PZT parts were also compared with those of the die-pressed PZT samples. The results indicated that the gel-forming process did not deteriorate the electrical properties of the samples, if proper dispersant was selected in developing concentrated ceramic slurry. [source] Crack,Tip Toughness of a Soft Lead Zirconate TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2003Alain B. Kounga Njiwa Crack,opening displacement (COD) measurements were performed on a commercial lead zirconate titanate (PZT). The intrinsic fracture toughness (or crack,tip toughness) of this material was determined using a new evaluation procedure, which takes into account the near,tip CODs and complete crack profile CODs. The crack,tip toughness KI0 was determined from an extrapolation of COD data obtained at various loading stages, thus avoiding the complications caused by subcritical crack growth in PZT. Results for plane strain and plane stress condition are presented. [source] Fabrication of NiO Nanoparticle-Coated Lead Zirconate Titanate Powders by the Heterogeneous Precipitation MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2003Ping-Hua Xiang NiO nanoparticle-coated lead zirconate titanate (PZT) powders are successfully fabricated by the heterogeneous precipitation method using PZT, Ni(NO3)2·6H2O, and NH4HCO3 as the starting materials. The amorphous NiCO3·2Ni(OH)2·2H2O are uniformly coated on the surface of PZT particles. XRD analysis and the selected-area diffraction (SAD) pattern indicate that the amorphous coating layer is crystallized to NiO after being calcined at 400°C for 2 h. TEM images show that the NiO particles of ,8 nm are spherical and weakly agglomerated. The thickness of the nanocrystalline NiO coating layer on the surface of PZT particle is ,30 nm. [source] Intrinsic Elastic, Dielectric, and Piezoelectric Losses in Lead Zirconate Titanate Ceramics Determined by an Immittance-Fitting MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2002Takaaki Tsurumi The material coefficients of "soft" and "hard" lead zirconate titanate (PZT) ceramics were determined as complex values by the nonlinear least-squares-fitting of immittance data measured for length-extensional bar resonators. The piezoelectric d -constant should be a complex value to obtain a best fitting between observed and calculated results. Because the elastic, dielectric, and piezoelectric losses determined in this process were not "intrinsic" losses, a calculation process to evaluate the "intrinsic" losses was proposed. It was confirmed that the intrinsic losses were smaller than the corresponding extrinsic losses. The intrinsic piezoelectric loss existed in both soft and hard PZTs; ,50% of the loss of piezoelectric d -constant was derived from the elastic and dielectric losses. The most notable difference between the soft and hard PZTs was observed in their elastic losses. [source] Fabrication of Optically Transparent Lead Lanthanum Zirconate Titanate ((Pb,La)(Zr,Ti)O3) Ceramics by a Three-Stage-Atmosphere-Sintering TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2002Yoshiyuki Abe An easy technique has been developed to fabricate optically transparent lanthanum-modified lead zirconate titanate (PLZT) ceramics. This technique consists of three stages: (1) sintering in an oxygen atmosphere, (2) elimination of pores in a carbon dioxide atmosphere, and (3) elimination of oxygen vacancies in an oxygen atmosphere. The carbon dioxide atmosphere enhances the diffusion of oxygen from the pores to outside the sintered body. The experimental results reveal that use of a carbon dioxide atmosphere effectively decreases residual pores and improves optical transmittance. From commercially available raw powders, an optical transmittance of 51% (wavelength of 550 nm) can be achieved for 0.7 mm thick polished PLZT9/65/35 ceramics using a carbon dioxide atmosphere, whereas the value is only 34% without a carbon dioxide atmosphere. The advantage of this technique is that PLZT ceramics having high optical quality can be obtained using conventional sintering tools. [source] Lead Zirconate Titanate Thin Films on Base-Metal Foils: An Approach for Embedded High-Permittivity Passive ComponentsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2001Jon-Paul Maria An approach for embedding high-permittivity dielectric thin films into glass epoxy laminate packages has been developed. Lead lanthanum zirconate titanate (Pb0.85La0.15(Zr0.52Ti0.48)0.96O3, PLZT) thin films were prepared using chemical solution deposition on nickel-coated copper foils that were 50 ,m thick. Sputter-deposited nickel top electrodes completed the all-base-metal capacitor stack. After high-temperature nitrogen-gas crystallization anneals, the PLZT composition showed no signs of reduction, whereas the base-metal foils remained flexible. The capacitance density was 300,400 nF/cm2, and the loss tangent was 0.01,0.02 over a frequency range of 1,1000 kHz. These properties represent a potential improvement of 2,3 orders of magnitude over currently available embedded capacitor technologies for polymeric packages. [source] Phase Stability and Ferroelectric Properties of Lead Strontium Zirconate Titanate CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2001Yongjian Yu The effect of compositional modifications on the field-induced phase-transition behavior and dielectric properties of strontium-doped lead zirconate titanate (PZT) ceramics was studied. PZT compositions with different strontium and titanium contents, within the general formula Pb1,xSrx(Zr1,yTiy)O3 and located in the tetragonal antiferroelectric (AFE) and rhombohedral ferroelectric (FE) phase fields were prepared by tape casting and sintering. X-ray diffraction and polarization measurements were used to locate compositions suitable for investigation of the field-induced AFE,FE phase transition. The results indicated that a higher Sr2+ content decreased the polarization and hysteresis and increased the switching field; a lower Ti4+ content decreased the polarization and increased the switching field and hysteresis. A high room-temperature dielectric constant was obtained for compositions near the phase boundary. These results suggest that a combination of both A -site and B -site modifications can be used to tailor ferroelectric properties, such as the switching field and hysteresis, of these strontium-doped PZTs displaying a field-induced AFE,FE phase transition. [source] Lead Zirconate Titanate Particle Dispersion in Thick-Film Ink FormulationsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2000Erik S. Thiele Diverse device applications for lead zirconate titanate (PZT) ceramics in thick-film form are currently in active development. In the present study, the particle dispersion properties of thick-film ink formulations containing PZT powder have been determined using rheological measurements. Although all of the eight commercially available dispersants tested are more effective than the terpineol solvent alone in decreasing attractive interparticle forces in suspensions, the best dispersant identified for hard and soft PZT powders is a phosphate ester oligomer. This dispersant is extremely efficient, and its use in thick-film ink formulations results in viscosity decreases of 50% at low shear rates (10 s,1) and 30% at high shear rates (100 s,1) compared with current ink formulations containing no dispersant. The effects upon rheology of the order of addition of components in the processing of inks have been studied, with the most effective processing route using a fugitive solvent that probably facilitates uniform coverage of the particle surfaces by the dispersant molecules. Modeling of the rheological profiles of inks indicates that the use of a dispersant decreases the depth of the primary minimum in the interparticle potential by a factor of 3. Demonstrated advantages of the use of a dispersant in PZT thick-film inks include improved microstructural homogeneity in the green body and the ability to formulate printable inks with higher solids loadings. No adverse effects of the dispersant upon the dielectric and piezoelectric properties of bulk PZT samples are found following burnout and sintering. [source] A comprehensive investigation of the structural properties of ferroelectric PbZr0.2Ti0.8O3 thin films grown by PLDPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2009David Walker Abstract X-Ray diffraction investigations were made of high-quality epitaxial thin films of the ferroelectric material lead zirconate titanate, PbZr0.2Ti0.8O3 (PZT), grown by pulsed laser deposition (PLD). Layers from 7 to 200,nm in thickness were studied, deposited on a 30,nm SrRuO3 (SRO) electrode on a [001] oriented SrTiO3 (STO) substrate. The out-of-plane lattice parameters of the PZT films were measured by high-resolution X-ray diffraction using CuK,1 radiation. A significant enhancement of the c lattice parameter with film thickness was observed, the maximum value of 4.25,Å reached in the 30,50,nm thick films. For film thicknesses greater than 100,nm, the c lattice parameter is relaxed, towards the bulk value of 4.13,Å at this composition. The in-plane lattice parameters were studied by Grazing incidence X-ray scattering (GIXS), using 15,keV synchrotron radiation at I16, Diamond. The a lattice parameter of domains with [001] oriented normal to the sample surface was effectively lattice matched to the SRO layer in the 7,nm ultra-thin film, but relaxed compared to the SRO in thicker films. The tetragonality of the [001] oriented domains decreases with increasing film thickness, approaching the bulk value of 1.05 in the thickest films. Evidence for the presence of [100] oriented a -domains was found in PZT films as thin as 30,nm, the proportion of which increased with increasing film thickness, suggesting they grow in order to relieve stresses that would prevent the epitaxial growth of thicker PZT films. The a -domains in the thicker films were found to be located nearer to the PZT/SRO interface than to the top surface of the PZT. [source] Phenomenological description of polarization switching in ferroelectric semiconductors with charged defectsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2005Anna N. Morozovska Abstract We have proposed the phenomenological description of polarization switching peculiarities in ferroelectric semiconductors with charged defects and prevailing extrinsic conductivity. More precisely, we have modified the Landau,Ginsburg approach and shown that the macroscopic state of the aforementioned inhomogeneous system can be described by three coupled equations for three order parameters. Both the experimentally observed coercive field values, well below the thermodynamic one, and the various hysteresis loop deformations (minor, constricted and double loops) have been obtained in the framework of our model. The obtained results qualitatively explain the ferroelectric switching in such bulk ferroelectric materials as SBN single crystals doped with Ce, lead zirconate titanate (PZT) films doped with Nd, and La-doped PZT ceramics. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A new approach to calculating powder diffraction patterns based on the Debye scattering equationACTA CRYSTALLOGRAPHICA SECTION A, Issue 1 2010Noel William Thomas A new method is defined for the calculation of X-ray and neutron powder diffraction patterns from the Debye scattering equation (DSE). Pairwise atomic interactions are split into two contributions, the first from lattice-pair vectors and the second from cell-pair vectors. Since the frequencies of lattice-pair vectors can be directly related to crystallite size, application of the DSE is thereby extended to crystallites of lengths up to ~200,nm. The input data correspond to unit-cell parameters, atomic coordinates and displacement factors. The calculated diffraction patterns are characterized by full backgrounds as well as complete reflection profiles. Four illustrative systems are considered: sodium chloride (NaCl), ,-quartz, monoclinic lead zirconate titanate (PZT) and kaolinite. The effects of varying crystallite size on diffraction patterns are calculated for NaCl, quartz and kaolinite, and a method of modelling static structural disorder is defined for kaolinite. The idea of partial diffraction patterns is introduced and a treatment of atomic displacement parameters is included. Although the method uses pair distribution functions as an intermediate stage, it is anticipated that further progress in reducing computational times will be made by proceeding directly from crystal structure to diffraction pattern. [source] Effect of heat treatment on the electrical properties of lead zirconate titanate/poly (vinylidene fluoride) compositesPOLYMER INTERNATIONAL, Issue 6 2010Lijie Dong Abstract Ceramic/polymer composites are attracting increasing interest in materials research and practical applications due to the combination of excellent electric properties of piezoelectric ceramics and good flexibility of polymer matrices. In this case, the crystallization of the polymer has a significant effect on the electric properties of ceramic/polymer composites. Based on different heat treatment methods, the crystallization of poly(vinylidene fluoride) (PVDF) in composites of lead zirconate titanate (PZT) and PVDF can be controlled effectively. PZT/PVDF composites with various PVDF crystallizations exhibit distinctive dielectric and piezoelectric properties. When the crystallization of PVDF is 21%, the PZT/PVDF composites show a high dielectric constant (,) of 165 and a low dielectric loss (tan ,) of 0.03 at 103 Hz, and when the crystallization of PVDF reaches 34%, the piezoelectric coefficient (d33) of PZT/PVDF composites can be up to ca 100 pC N,1. By controlling the crystallization of PVDF, PZT/PVDF composites with excellent dielectric and piezoelectric properties were obtained, which can be employed as promising candidates in high-efficiency capacitors and as novel piezoelectric materials. Copyright © 2010 Society of Chemical Industry [source] A novel route to perovskite lead zirconate titanate from glycolate precursors via the sol,gel processAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 2 2008N. Tangboriboon Abstract A perovskite lead zirconate titanate was synthesized by the sol-gel process, using lead glycolate, sodium tris(glycozirconate) and titanium glycolate as the starting precursors. For the mole ratio Pb:Zr:Ti of 1:0.5:0.5 [Pb(Zr0.5Ti0.5)O3], TGA-DSC thermal analysis indicated that the percentage of ceramic yield was 55.8, close to the calculated chemical composition value of 49.5. The exothermic peak occurred at 268 °C below the theoretical Curie temperature of 400 °C. The pyrolysis of Pb(Zr0.5Ti0.5)O3 of the perovskite phase was investigated in terms of calcination temperature and time. The structure obtained was of the tetragonal form when calcined at temperatures below 400 °C; it transformed to the tetragonal and the cubic forms of the perovskite phase on calcination above the Curie temperature, as verified by X-ray data. The lead zirconate titanate synthesized and calcined at 400 °C for 1 h had the highest dielectric constant, the highest electrical conductivity and the dielectric loss tangent of 10 190, 0.803 × 10,3 (,.m),1 and 1.513 at 1000 Hz, respectively. The lead zirconate titanate powder synthesized has potential applications as an electronic material. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||