PZT Phase Research Articles

Template-Assisted Fabrication of Double-Shelled Nanotubes Composed of Inner Shell Pb(Zr0.52Ti0.48)O3and Outer Shell TiO2by Sol-Gel Process with Spin-Coating Technique

ABSTRACTDouble-shelled nanotubes composed of inner shell Pb(Zr0.52Ti0.48)O3(PZT) and outer shell TiO2are successfully fabricated by a spin coating of each sol-gel solution on porous anodic alumina template. Field emission transmission electron microscopy images show that they have a ~ 10 nm wall thickness. The selected area electron diffraction patterns show that they have two mixed crystalline phases of tetragonal PZT and anatase TiO2. The analyses of scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy confirm their uniform distribution of each element.

Influence of crystal phase and transparent substrates on electro-optic properties of lead zirconate titanate films

Pb ( Zr x Ti 1 − x ) O 3 [x=0.52, PZT(52) near morphotropic phase boundary], tetragonal PZT(65), and rhombohedral PZT(20) thin films have been fabricated on different transparent substrates by radio frequency sputtering. The optical studies show that the band gap energies and refractive indices of the PZT thin films are crystal phase dependent. The largest electro-optic (EO) coefficient of 219.6 pm/V has been achieved by controlling the crystal phase of the PZT thin films. The linear EO coefficients of PZT(52) films on the (Pb0.86La0.14)TiO3-coated glass, indium tin oxides, and MgO substrates are also studied. Such study could contribute to the crystal phase and substrate dependent PZT films for electro-optic devices and multifunctional integrated circuits.

The Use of PbF2 for Low Temperature Sintering of Lead Zirconate Titanate Ceramics

Lead Zirconate Titanate (PZT) ceramics with the formula of Pb(Zr0.52Ti0.48)O3-xFx where x = 0, 0.01, 0.02, 0.03 and 0.05 were produced by a conventional mixed oxides route. The phase structures of all calcined PZT powders investigated using XRD technique revealed that the addition of PbF2 could reduce the calcination temperature. The single phase PZT for the powders with more than 3 mol% of PbF2 could be obtained at the temperature as low as 600°C. PZT ceramics with PbF2 3 and 5 mol% gave the highest density at the sintering temperature of 1050°C without a second phase. These calcination and sintering temperatures are much lower than the temperature normally needed in the production of a pure PZT ceramic which the usual calcinations and sintering temperatures are about 800°C and 1200°C, respectively. The microstructures of PZT ceramics with various amounts of PbF2 were investigated using SEM technique. The dielectric and piezoelectric properties such as d33, ϵr and P-E loops were also investigated. The dielectric measurement of PZT ceramics with the addition of PbF2 indicated a softening effect since fluorine (F) could act as donor by increasing dielectric nonlinearity of permittivity and loss.

Effects of superimposed electric field and porosity on the hydrostatic pressure-induced rhombohedral to orthorhombic martensitic phase transformation in PZT 95/5 ceramics

The hydrostatic pressure-induced martensitic transformation from the ferroelectric rhombohedral to antiferroelectric orthorhombic phase in PZT 95/5 ceramics has been studied using neutron diffraction. The transition to the orthorhombic phase initiates at a pressure of 260 MPa and is almost complete at 290 MPa. This stress range is much narrower than that observed in uniaxial loading, which starts at 200 MPa and is incomplete even at 400 MPa. The narrower stress range observed under hydrostatic loading is attributed to a lack of internal stress developed during the transformation. By contrast, the work required to start the transformation is approximately the same under both types of loading. The transformation progresses more gradually with increasing pressure when a static electric field is applied to a specimen in a pre-poled state. Tests carried out on porous specimens, having a relative density of approximately 90%, demonstrated that the transformation occurred over a narrow pressure range but with a lower transformation pressure of approximately 220 MPa.

ChemInform Abstract: Phase Homogeneity and Segregation in PZT Powders Prepared by Thermal Decomposition of Metal-EDTA Complexes Derived from Nitrate and Chloride Solutions.

Fine, homogeneous lead zirconate titanate (PZT) powders have been prepared by the thermal decompostion of metalorganic complexes derived from nitrate solutions using ethylenediaminetetraacetic acid (EDTA) as a complexing agent. It has been shown that nitrate ions accelerate the decomposition of the precursor and the crystallization of the PZT phase initiates at temperatures as low as 250°C. No intermediate phases, other than PbO, were found. The coexistence region of the rhombohedral and tetragonal phases in the sintered ceramic was found to be a little over 1 at.%. The chloride-EDTA precursor did not form the desired PZT phase, even after calcination at 1000°C. The segregation and loss of lead was observed for this material, due to the formation and evaporation of PbCl2. DTA/TGA, SEM, and XRD were employed to characterize the powders. The use of TEM with nanoprobe energy dispersive X-ray analysis (EDX), allowed the identification of the phase segregation in the chloride-EDTA derived powder. A possible reaction mechanism for this phase segregation is suggested.

Phase-shifting laser scanning confocal microscopy moiré method and its applications

The laser scanning confocal microscopy (LSCM) moiré method is an effective method for full-field displacement and strain measurement in the micrometer scale. In this study, the phase-shifting LSCM moiré method is proposed for automatic processing of the moiré fringe. A combined phase-shifting and loading system for LSCM was developed, which could offer a tensile load on the plate type sample with a maximum load range of up to 500 N. Using the PZT (piezoelectric ceramic) phase shifter in the loading system, the moiré fringe phase was shifted and measured. Full field deformation was calculated according to the phase data. With the combination of LSCM and the self-developed loading system, tensile deformation of the aluminum sample was measured by the phase-shifting LSCM moiré technique. Full-field deformations under the different loads and elastic modulus of the sample were obtained. Experimental results demonstrated the feasibility of this technique, and the accuracy for deformation measurement is clearly improved.

ELECTRICAL AND MECHANICAL PROPERTIES OF PZT/PVDF 0–3 COMPOSITES

Granules of in-house prepared PZT ceramic and powder of commercially available PVDF polymer were used as starting materials to form a series of x PZT /(1 - x) PVDF composites (where x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) with 0–3 connectivity. Densities of the composites tended to increase with increasing PZT ceramic content. Phase and microstructure of the composites revealed homogeneous mixture between PZT and PVDF phases. The composites with higher ceramic content had higher dielectric constant and dielectric loss tangent. Ferroelectric measurement revealed the effect of PZT phase connectivity in 0.9PZT/0.1PVDF ceramic in which a sudden jump in ferroelectric properties was observed. Mechanical properties in terms of hardness, Young's modulus and fracture toughness were also improved when PZT content was increased.

Piezoelectric Pb(Zr0.52Ti0.48)O3 thin films on single crystal diamond: Structural, electrical, dielectric, and field-effect-transistor properties

The combination of piezoelectric materials and single crystal diamond offers the opportunity for the development of multifunctional micromachined devices under extreme conditions. In this work, the authors report the structural, electrical, optical, and dielectric properties of Pb(Zr0.52,Ti0.48)O3 (PZT) thin films integrated on single crystal diamond (100) substrates. The corresponding field effect transistor based on the metal-piezoelectric-insulator-semiconductor (MPIS) structure was fabricated on a homoepitaxial p-type diamond layer grown on a type-Ib diamond substrate. Different intermediate layers were deposited on single diamond substrates prior to the PZT films growth in order to achieve the best polarization properties. It was observed that the utilization of an Al2O3 buffer layer followed by a SrTiO3 seed layer favored the formation of a single perovskite PZT phase. Transmission electron diffraction patterns revealed that the PZT films included an initial layer at the SrTiO3/PZT interface followed by a well crystallized layer. The PZT film grown on SrTiO3/Al2O3/diamond exhibited much better in-plane polarization than that of the PZT film on Al2O3/diamond. The photoresponse behavior revealed that carriers trapping effect was trivial in the PZT film. The channel electrical conductivity of the MPIS field effect transistor was successfully modulated by the gate bias.

Interfacial morphology and domain configurations in 0-3 PZT–Portland cement composites

Cement-based piezoelectric composites have attracted great attention recently due to their promising applications as sensors in smart structures. Lead zirconate titanate (PZT) and Portland cement (PC) composite were fabricated using 60% of PZT by volume. Scanning Electron Microscope and piezoresponse force microscope were used to investigate the morphology and domain configurations at the interfacial zone of PZT–Portland cement composites. Angular PZT ceramic grains were found to bind well with the cement matrix. The submicro-scale domains were clearly observed by piezoresponse force microscope at the interfacial regions between the piezoelectric PZT phase and Portland cement phase, and are clearer than the images obtained for pure PZT. This is thought to be due to the applied internal stress of cement to the PZT ceramic particle which resulted to clearer images.

Dynamic magneto-electric multiferroics PZT/CFO multilayered nanostructure

Highly oriented PbZr0.53Ti0.47O3/CoFe2O4(PZT/CFO) multilayered nanostructures (MLNs) were grown on MgO substrate by pulsed laser ablation using La0.5Sr0.5CoO3 (LSCO) as conducting bottom electrode. The effect of various PZT/CFO (PC) sandwich configurations having three, five, and nine layers while maintaining total thickness of PZT and CFO be identical has been systematically investigated. X-ray diffraction (XRD) and micro-Raman spectra revealed the existence of pure PZT and CFO phases without any intermediate phase. Intact MLNs were observed by transmission electron microscopy (TEM) with little inter-diffusion near the interfaces at nano-metric scale without any impurity phase. Impedance spectroscopy, modulus spectroscopy, and conductivity spectroscopy were carry out over a wide range of temperatures (100–600 K) and frequencies (100 Hz–1 MHz) to investigate the grain and grain boundary effect on electrical properties of MLNs. Temperature dependent real dielectric permittivity and dielectric loss illustrated step-like behavior and relaxation peaks near the step-up characteristic, respectively. Cole–Cole plots indicate that most of the dielectric response came from the bulk (grain) MLNs below 300 K, whereas the grain boundary and the electrode–MLNs effects are prominent at elevated temperatures. The dielectric loss relaxation peak shifted to higher frequency side with increase in temperature, it was out of the experimental frequency window above 300 K. Our Cole–Cole fitting of dielectric loss spectra indicated marked deviation from the ideal Debye-type of relaxation, which is more at elevated temperature. Master modulus spectra supported the observation from the impedance spectra; it also indicated that the magnitude of the grain boundary compared to grain becomes more prominent with increase in number of layers. We have explained these electrical properties of MLNs by Maxwell–Wagner type contributions arising from the interfacial charge at the interface of the ML structures. Three different types of frequency dependent conduction processes were observed at elevated temperatures (>300 K), which fitted well with the double power law, \( \sigma \left( \omega \right) = \sigma \left( 0 \right) + A_{1} \omega^{{n_{1} }} + A_{2} \omega^{{n_{2} }} , \) indicating that the low frequency (<1 kHz) conductivity may be due to long-range ordering (frequency independent), mid frequency conductivity (<10 kHz) may be due to short-range hopping, and high frequency (<1 MHz) conduction due to the localized relaxation hopping mechanism. Ferroelectric polarization decreased slowly in reducing the temperature from 300 to 200 K, with complete collapse of polarization at ~100 K, but there was complete recovery of the polarization during heating, which was repeatable over many different experiments. At the same time, the temperature dependent remanent magnetization of the MLNs showed slow enhancement in the magnitude till 200 K with three-fold increase at 100 K compared to room temperature. This enhancement in remanent magnetization and decrease in remanent ferroelectric polarization on lowering the temperature indicate temperature dependent dynamic switching of ferroelectric polarization. The magnetic and ferroelectric properties of MLNs were quite different compared to individual layers suggesting its improper ferroelectric characteristics. The fatigue test showed almost 0–20% deterioration in polarization. Fatigue and strong temperature and frequency dependent magneto-electric coupling suggest MLNs utility for Dynamic Magneto-Electric Random Access Memory (DMERAM).

Crystal structure of the rhombohedral phase ofPbZr1−xTixO3ceramics at room temperature

${\text{PbZr}}_{1\ensuremath{-}x}{\text{Ti}}_{x}{\text{O}}_{3}$ (PZT) ceramics made by mixed-oxide and sol-gel routes within the rhombohedral region of the phase diagram have been prepared, and their structures determined by Rietveld refinement using high-resolution time-of-flight neutron diffraction. Different structural models have been used but the best fits have been found using a mixture of rhombohedral $R3c$ $({C}_{3v}^{6})$ and monoclinic $Cm$ $({C}_{s}^{3})$ across the whole rhombohedral range with the proportion of monoclinic phase increasing continuously with composition $x$ toward the morphotropic phase boundary. Some differences are found between the ceramics prepared by the two routes, especially with respect to the diffraction peak widths, suggesting that the precise structural arrangements in these materials depend on the method of preparation. The results show that PZT ceramics made in this region always consist of mixed phases and this accounts for the fact that no phase boundary has been discovered in the PZT phase diagram between the monoclinic and rhombohedral phases.

Phase transitions in xPbZr0.53Ti0.47O3-(1 − x)Mn0.4Zn0.6Fe2O4 magnetoelectric composites

The elastic, inelastic, and dielectric properties of the magnetoelectric composite xPbZr0.53Ti0.47O3-(1 − x)Mn0.4Zn0.6Fe2O4 (PZT-MZF) are studied in the temperature range from room temperature to 673 K. The influence of the ferroelectric PZT phase on the magnetic phase transition and the magnetic MZF phase on the ferroelectric phase transition is revealed. It is established that, as the PZT content increases, the degree of diffuseness of the phase transition decreases and a gradual crossover from a pronounced relaxor behavior to a more ordered ferroelectric behavior occurs.

Multiferroic Properties of CoFe2O4/PbZr0.52Ti0.48O3 Composite Ceramics

The xCoFe 2 O 4 -(1−x)PbZr 0.52 Ti 0.48 O 3 (PZT) composite ceramics with x = 0.1, 0.2 and 0.3 have been prepared by solid state reaction method. X-ray diffraction result reveals that no chemical reaction or phase diffusion between the CoFe 2 O 4 and PZT phases exists in the composites. The composites exhibited ferroelectric as well as magnetic characteristics at room temperature. The distribution of the ferroelectric and magnetic domains has been observed by Scanning Probe Microscopy (SPM). The dielectric properties of the composite ceramics were also investigated. The dependence of dielectric properties and the morphology of both the ferroelectric and magnetic domains on CoFe 2 O 4 concentration were discussed in detail.

Electromagnetic properties of low-temperature co-fired xPZT+(1− x)NiCuZn–ferrite composites

To adjust the dielectric constant and the initial permeability of NiCuZn–ferrite materials for suppressing electromagnetic interference, Pb 0.95Sr 0.05(Zr 0.52Ti 0.48)O 3 (PZT) was introduced. The effects of PZT additive on the phase composition, densification, microstructures and electromagnetic properties of the ceramics with composition of xPZT+(1− x)NiCuZn–ferrite (where x=0–25 wt%) were investigated. The results show that these composites are mainly of spinel phase, exhibiting relatively high dielectric constant and initial permeability due to the mutual effects of magnetization of NiCuZn–ferrite phase and polarization of PZT phase. Meanwhile, relatively high-quality factor ( Q) and excellent frequency stability were obtained for the samples with PZT additive. These materials are expected to be used as embedded inductors or embedded capacitors.

Ideal barriers to polarization reversal and domain-wall motion in strained ferroelectric thin films

The ideal intrinsic barriers to domain switching in $c$-phase ${\text{PbTiO}}_{3}$ (PTO), ${\text{PbZrO}}_{3}$ (PZO), and ${\text{PbZr}}_{1\ensuremath{-}x}{\text{Ti}}_{x}{\text{O}}_{3}$ (PZT) are investigated via first-principles computational methods. The effects of epitaxial strain on the atomic structure, ferroelectric response, barrier to coherent domain reversal, domain-wall energy, and barrier to domain-wall translation are studied. It is found that PTO has a larger polarization, but smaller energy barrier to domain reversal, than PZO. Consequentially the idealized coercive field is over two times smaller in PTO than PZO. The Ti-O bond length is more sensitive to strain than the other bonds in the crystals. This results in the polarization and domain-wall energy in PTO having greater sensitivity to strain than in PZO. Two ordered phases of PZT are considered, the rocksalt structure and a (100) PTO/PZO superlattice. In these simple structures we find that the ferroelectric properties do not obey Vergard's law, but instead can be approximated as an average over individual five-atom unit cells.

Phase measurement through sinusoidal excitation with application to multi-wavelength interferometry

In this paper we present a novel approach to obtain interference phase measurements using sinusoidal modulation in order to obtain high resolution data at high temporal bandwidths. The use of classical phase stepping techniques generates ringing in PZT-based phase modulators and hence limits the temporal bandwidth at which reliable phase data can be obtained. Signal processing techniques are introduced to extract intensity measurements at any required phase step and hence offer compatibility with existing linear phase shifting interferometry algorithms. It was found that, under high frequency and/or high amplitude sinusoidal excitation, the PZT phase modulator could exhibit a nonlinear response. Strategies are introduced to mitigate these effects on the calculated interference phase. Experimental data is presented demonstrating a phase resolution of 1/600th of a fringe at a temporal bandwidth of 8150 Hz when using the Carre phase stepping algorithm. Data from a multi-wavelength fibre interferometer with sinusoidal modulation to obtain the wrapped phase measurements are also presented where a dynamic range of 1 part in 2 × 106 was achieved.

Preparation and characterization of Pb(Zr 0.53Ti 0.47)O 3/CoFe 2O 4 composite thick films by hybrid sol–gel processing

Pb(Zr 0.53Ti 0.47)O 3/CoFe 2O 4 (PZT/CFO) multiferroic thick films were prepared using hybridized sol–gel processing and followed by systematic characterization investigations. PZT sol–gel solution, PZT and CFO nanopowders were used to fabricate the PZT/CFO thick films on Pt/Ti/SiO 2/Si substrate. In this process, sol–gel solution was employed as the buffer layer between the substrate and thick films, the capping layer on the top of thick films; it was also mixed with PZT nanopowder for obtaining and adjusting homogenerous slurry, and to disperse CFO nanopowder into it to form heterogenerous slurry. PZT sol–gel solution and two kinds of slurry were spin-coated onto the substrate layer by layer and then annealed. X-ray diffraction results showed that PZT and CFO phases coexisted in the thick films without any other detectable impurity phase. SEM micrographs of thick film cross-sections exhibited composite structures without any visible boundary between different layers. With increasing annealing temperature, PZT/CFO multiferroic thick films became porous and the bottom electrode (Pt) was peeling off from the substrate above 700 °C due to Ti diffusion into Pt layer. Their thickness observed from SEM cross-sectional pictures is 3.31 μm annealed at 600 °C and 2.63 μm annealed at 650 °C. Ferroelectric and ferromagnetic properties of thick films were measured, evidencing the multifunctional properties in these films.

Optimization of synthesis of the solid solution, Pb(Zr1–xTix)O3 on a single substrate using a high-throughput modified molecular-beam epitaxy technique

Synthesis of Pb(Zr1–xTix)O3 (PZT) on a single substrate using a high-throughput molecular-beam epitaxy technique was demonstrated. In situ synthesis of crystalline PZT at elevated substrate temperatures could not be achieved, as reevaporation of Pb (PbO) occurred and the partial pressure of O2 was insufficient to prevent formation of a PbPtx phase during deposition. Instead, ex situ postdeposition annealing was performed on PZT deposited at room temperature. Dense single phase PZT was prepared with a compositional range of 0.1 &gt; x &gt; 0.9, for film thicknesses up to 800 nm. Transmission electron microscopy revealed the grain size increased from 50 nm to ∼0.5 μm with increasing Zr-concentration and became more columnar. Raman, x-ray diffraction, and scanning electron microscopy/energy dispersive spectroscopy results revealed a morphotropic phase boundary between rhombohedral and tetragonal phases occurred at x ∼0.4 rather than at x = 0.47 in bulk ceramics. This was attributed to clamping arising from mismatch in thermal expansion between the film and substrate.

A novel nanostructure and multiferroic properties in Pb(Zr0.52Ti0.48)O3/CoFe2O4 nanocomposite films grown by pulsed-laser deposition

Multiferroic nanocomposite thin films containing Pb(Zr0.52Ti0.48)O3 (PZT) and CoFe2O4(CFO) with a novel nanostructure are deposited on (1 0 0)-oriented Nb-doped SrTiO3 (STO) substrates by pulsed-laser deposition. Structural characterizations show that only PZT and CFO phases exist in the composite films, and the perovskite-structured PZT nano-pyramids with diameters of 50–100 nm are randomly embedded in the spinel-structured polycrystalline CFO matrix. Ferroelectric and magnetic hysteresis loops are simultaneously observed at room temperature. Magnetic-field-dependent capacitance measurement reveals an increase in capacitance of about 1.46% with an applied magnetic field. The multiferroic properties in the nanocomposite are also characterized by ferroelectric and magnetic domain imaging in the local areas of the sample.

Monoclinic phase in PZT: order parameter and phase transition from Tetragonal Phase

A solution of the Lagrange–Euler equations for the order parameter–the electric polarisation vector P–which describes the monoclinic phase in PZT is found exactly in this article for the Gibbs free energy expansion done for the cubic phase up to the sixth–order in the order parameter. The phase transition from the tetragonal phase to the monoclinic phase in materials of the PZT type may be described within the Landau theory of phase transitions used by Haun and co-workers. The phase transition is found to be of the first order in general. The order parameter in the parameter space is two dimensional: the amplitude A and the angle. The PZT material has values of expansion coefficients in the Gibbs free energy such that the exact solution for description of the monoclinic phase is a metastable state. We may conclude then that the monoclinic phase exists in PZT due to higher than sixth-order terms in the Gibbs free energy expansion which are present due to high anharmonicity present in this material.