PZT Phase Research Articles

Improvement of Ferroelectric Properties of PZT Ceramics by SBT Addition

(1−x)PZT-xSBT ceramics were prepared by a solid-state mixed oxide method. Phase characteristics of (1−x)PZT-xSBT ceramics showed a PZT phase and new phase in the compositions with 0.1 ≤ x ≤ 0.3, while a mainly new phase was observed in the composition with x = 0.5. The tetragonality (c/a) of PZT phase decreased with increasing in SBT content up to x = 0.3. SEM micrographs of the sample surface showed equiaxed grains of the PZT phase and irregularly-shaped grains of the new phase in samples with 0.1 ≤ x ≤ 0.3. The 0.5PZT-0.5SBT sample showed mainly irregularly-shaped grains of the new phase. The ferroelectric properties of these samples showed that the addition of small amounts of SBT (x = 0.1) into PZT increased the remanent polarization.

BiCo<sub>1-<i>x</i></sub>Fe<i><sub>x</sub></i>O<sub>3</sub>の分極回転現象

Polarization rotation is the key for interpretation of the piezoelectricity in Pb（Ti1-xZrx）O3（PZT）and other piezoelectric ceramics. We found the monoclinic phase in BiCo1-xFexO3（x～0.7）that is isostructural with the low temperature phase of PZT at the morphotropic phase boundary（MPB）. Precise structural analysis by electron diffraction and powder synchrotron X-ray diffraction revealed that the monoclinic perovskite BiCo1-xFexO3 exhibits Cm symmetry and showed polarization rotation as functions of composition and temperature. The second order structural transition from tetragonal to monoclinic structures was accompanied by a rotation of the polarization vector from the［001］to［111］directions of a pseudo cubic cell.

菲索干涉仪中精确移相的实现

To realize the high accuracy measurement of optical surfaces by a phase-shifting Fizeau interferometer,a synchronous acquisition phase-shifting system in the interferometer was established,and an accurate phase shifting method was researched.First,the composition and working principle of the phase-shifting system were introduced.Then,the velocity of PZT phase shifter during measurement was calculated.Since there exist defocus errors as well as speed-up and speed-down steps during phase shift,the moving process of phase shifter was detailedly designed.Finally,the phase shifter was calibrated.A verified experiment was carried out on the modified interferometer,and it shows that the RMS simple repeatability is λ/11 340.Comparative measurement was also carried out with two same components between the modified interferometer and the Verifire XP/D interferometer(Zygo company),and the RMS difference is about 0.9 nm.It can be seen that the repeatability and accuracy of this phase-shifting system and phase-shifting method have satisfied the requirement of nano-scale form measurement,which can provide references for developing high accuracy phase-shifting interferometers.

Pb(Zr<sub>0.52</sub>Ti<sub>0.48</sub>)O<sub>3</sub> Ceramics Synthesized Using Planetary Ball Mill

Lead zirconate titanate Pb (Zr0.52Ti0.48)O3, (PZT) ceramic was successfully prepared from the mixture of commercial PbO, TiO2 and ZrO2 powders using planetary ball mill at room temperature. The phase formation and microstructure of the milled powders were characterized using X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). XRD results indicated that the perovskite phase of PZT was formed from the mixture of starting materials after milling for 40 h. The grain sizes of the powders have been estimated from the SEM images to be ~200 nm. The compacted PZT samples were then sintered at 950 °C for 1 h. The samples were characterized by XRD and SEM, meanwhile the density was measured by Archimedes principle. XRD analysis on the sintered samples revealed the formation of single phase Pb (Zr0.52Ti0.48)O3 ceramics while the SEM images estimated the grain size to be ~2 µm. The relative density of the obtained sintered PZT ceramics was measured to be approximately 99.93 % of the theoretical density. The results hence indicate that planetary ball mill is an effective preparatory technique to improve the sinterability of PZT ceramics.

Output characteristics in Fe–Pd/PZT/Fe–Pd magneto-electric composites with Fe–Pd thick layer

Magneto-electric (ME) characteristics of the ferromagnetic/ferroelectric Fe70Pd30/PZT/Fe70Pd30 thin composites were investigated. The ME composites composed of the ferroelectric PZT phase (center layer, t: 260μm) and the ferromagnetic, magnetostrictive Fe70Pd30 phase (t: 30–90μm) glued on both the surfaces of PZT were fabricated. The rapidly solidified Fe70Pd30 ribbon mainly consists of fct martensitic phase with a large magnetostriction and fcc austenite (parent) phase. According to the DC bias magnetic field dependency of the output ME voltage (VME) at an AC magnetic field of 1.0Oe with an operation frequency of 1kHz for the composites, the increasing in thickness of magnetostrictive layers showed remarkable improvement of VME values. For the composite with 90μm Fe–Pd layers, maximum VME value of 13.9mV was obtained at 60Oe of the DC field, which is about two times higher than that of the composite with 30μm Fe–Pd layers. Additionally the VME value of the serial circuit was monotonically enhanced by the serial circuit connection, and the composites exhibited a very large peak at a resonant frequency of 61–68kHz.

Optical and structural properties of low thickness lead zirconate titanate films on sapphire substrates prepared via sol-gel method

Lead zirconate titanate (PZT) thin films in the range of 35–90 nm were deposited on a sapphire (1000) substrate using the sol-gel preparation method by diluting a PZT solution at different levels and using dichloromethane as the solvent. The microstructure, surface morphology, and stoichiometry of the films were studied by x-ray diffraction, atomic force microscopy, and Rutherford backscattering. Very smooth films characterized by single perovskite and mixed pyrochlore/perovskite polycrystalline phases were obtained and their optical properties were studied by spectroscopic ellipsometry in the ultraviolet–visible–near-infrared region. The refractive index was evaluated by analyzing the spectroscopic ellipsometry spectra. The ellipsometric data were also used to evaluate the bandgap energy of the films. The results show that the optical parameters of the films depend on the crystalline structure and demonstrate that higher bandgaps are obtained for perovskite films as compared to pyrochlore or mixed pyrochlore/perovskite structures. Data also confirm the higher bandgap of the amorphous structure compared to the polycrystalline PZT phases.

Synthesis and Characterization of Nanocrystalline PZT Powders by a Simple Sol-Gel Method

Nanocrystalline lead zirconate titanate (PZT) powders with composition at the morphotropic phase boundary (MPB) were synthesized by a simple aqueous based sol-gel method, using lead nitrate, zirconium nitrate and tetrabutyl titanate as the starting materials. The sol could be easily transformed into gel, firstly heated at 120°C for 10h, then at 180°C for 24h. The thermal decomposition process of the gel was investigated by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The effect of citrate addition amount on the calcining temperature was discussed. The results reveal that pure perovskite phase PZT powders can be obtained at a calcining temperature as low as 600°C. The average grain size of the powders was determined by transmission electron microscope and X-ray diffraction. The influences of calcining temperature and the pH value of the solution on the grain size were investigated. The sintering temperature and electrical properties of the ceramics derived by nano-powders were compared with those prepared by the conventional ceramic processing. The result shows that using the nanopowder, the sintering temperature could be reduced by about 100°C and the ferroelectric properties were enhanced.

Influence of buffer layer on structural, electrical and mechanical properties of PZT/NiTi thin film heterostructures

Ti and TiN layers of 8–10nm thickness were employed as a buffer layer to improve the structural, electrical and mechanical properties of Pb(Zr0.52Ti0.48)O3(PZT)/NiTi heterostructures synthesized using dc/rf magnetron sputtering. The buffer layers were deposited on NiTi prior to the growth of PZT films. It was observed that the incorporation of buffer layer favored the formation of single perovskite PZT phase with no evidence of pyrochlore phase. Further, the properties of these heterostructures were observed to change with corresponding change in crystalline orientation of top PZT layer. The PZT/NiTi heterostructures with additional buffer layer exhibited enhanced remnant polarization (Pr) and dielectric constant (ε). A sudden increment in the dielectric constant was observed for PZT/buffer/NiTi heterostructures near room temperature. This could be attributed to the increasing ionic displacement of Ti ion with respect to the O ion in PZT films due to the stress induced by the martensite variants of NiTi layer during phase transformation from a low temperature martensite phase to high temperature austenite phase. This transformation promotes the strain-induced polarization and henceforth enhancing the dielectric constant of PZT films. Nanoindentation studies indicate the maximum hardness of 7.6GPa and indentation modulus of 206GPa for PZT(111)/TiN/NiTi heterostructure.

Magnetoelectric properties of PbZr0.53Ti0.47O3–Ni0.65Zn0.35Fe2O4 multiferroic nanocomposites

A different kind of multiferroics with ferroelectric–ferrimagnetic (FE–FM) composites: (1 − x) PbZr0.53Ti0.47O3–x Ni0.65Zn0.35Fe2O4 with x = 0.10, 0.20 and 0.30, were synthesized by a powder-in-sol precursor hybrid processing route. Structural analysis with X-ray diffraction (XRD) data revealed the presence of both PbZr0.53Ti0.47O3 (PZT) and Ni0.65Zn0.35Fe2O4 (NZFO) pure phases in the PZT–NZFO composites. Scanning electron micrographs (SEM) clearly disclose distribution of both PZT and NZFO phases throughout the sample. Dielectric and electrical properties of the system have been investigated in a wide range of frequency at different temperatures. Dielectric constant (er) as a function of temperature reveals the paraelectric–FE transition temperature at ~408 °C having maximum value of er at the peak [e r max = 1,200] with another low temperature anomaly at ~297 °C, very close to the magnetic Curie temperature of the NZFO ferrite (Tc = 300 °C) for the x = 0.1 FE–FM composite. The impedance spectroscopy data of these composites show clearly, contribution of both grain and grain boundary effect in the electrical properties of the composites. Negative temperature coefficient of resistance (NTCR) behavior of the materials indicates their semi-conducting nature. The ac conductivity spectrum is found to obey Johnscher’s power law very well. The temperature-dependent magnetization hysteresis (M–H) loops of the PZT/NZFO composite show excellent non-saturating ferrimagnetic behavior with increase in both coercive field (Hc) and remanent magnetization (Mr) when the NZFO content in the composite is increased. Polarization (P) versus electric field (E) studies at 300 K give conclusive evidence of the presence of spontaneous polarization in all the three composites (x = 0.1, 0.2 and 0.3). However, area of P–E loop, coercive field (Ec) and remanent polarization (Pr) are found to decrease noticeably with the increase of the NZFO content (x) in these composites.

Epitaxial growth of Pb(Zr0.53Ti0.47)O3 films on Pt coated magnetostrictive amorphous metallic substrates toward next generation multiferroic heterostructures

Piezoelectric films of Pb(Zr0.53Ti0.47)O3 (PZT) were deposited by pulsed laser deposition onto metallic magnetostrictive substrates. In order to optimize the growth of PZT films, a buffer layer of Pt was employed, as well as variation of deposition temperature, pressure, and laser energy. Room temperature θ-2θ x-ray diffraction measurements indicate all diffraction features correspond to reflections indexed to a single PZT phase of space group P4mm. Scanning electron microscopy images reveal pinhole-free dense films of pyramidal shaped crystal arrangements whose orientation and size were controlled by variation of oxygen pressures during deposition. The resulting PZT films had a value of d33 ∼ 46 pm/V representing a 53% increase over previous efforts to realize a piezoelectric/Metglas™ film heterostructure.

Rhombohedral and Monoclinic Phases of PZT near the Antiferroelectric and the Morphotropic Boundaries

Anelastic and dielectric spectroscopy measurements are presented, which, together with previous measurements [1], clarify some controversial aspects of the phase diagram of PbZr1xTixO3close to the border with the antiferroelectric (AFE) phase, and at the morphotropic phase boundary (MPB). No evidence is found of a border separating monoclinic (M) from rhombohedral (R) phases, supporting recent structural studies according to which the two phases coexist, with the fraction of M prevailing near the MPB. A large frequency independent softening at the MPB indicates a genuine M phase over only finely twinned R phase. A new phase transition is found in both the anelastic and dielectric spectra atx= 0.1, at a temperatureTITbetween the Curie temperatureTCand the boundaryTTto the phases with tilted octahedra. Such a diffuse transition is interpreted as onset of disordered tilts, which finally become ordered belowTT. In this manner, the phase diagram of PZT is rationalised with respect to the common tendency of perovskites to undergo tilting when the mismatch between the cation sizes exceeds a threshold.

Preparation and characteristics of fine-grained ferroelectric glass-ceramic composites via a modified hybrid route at low temperature sintering

Dense, homogeneous and fully developed fine-grained ferroelectric Pb(Zr0.53Ti0.47)O3–based glass-ceramics have been successfully prepared at a low-sintering temperature of 850–900°C by a modified hybrid process in air. The influence of the PbO-B2O3-SiO2 (abbreviated as PBS) glass-gel content on the microstructure, dielectric, and ferroelectric properties of such glass-ceramics has been investigated. The temperature dependence of the dielectric constant indicated that the fine-grained Pb(Zr0.53Ti0.47)O3 (abbreviated as PZT(53/47)) based glass-ceramic shows the characteristic dispersion at the Curie point. Ferroelectric hysteresis loop analyses have been performed to manifest the ferroelectric nature of the highly crystallized PZT(53/47) phase prepared by this modified novel hybrid process despite containing higher wt% glass-gel contents. The best dielectric and ferroelectric properties in a typical sample with 5% by weight of glass-gel content were found to have dielectric constant and loss tangent of 920 and 0.02 at 1 kHz, respectively. The saturation polarization (P s ), and remanent polarization (P r ) as well as the coercive field (E c ) are 21.9 μC/cm2, 10.8 μC/cm2 and 2.19 kV/mm, respectively.

Processing and magneto-electric properties of sol–gel-derived Pb(Zr0.52Ti0.48)O3–Ni0.8Zn0.2Fe2O4 2-2 type multilayered films

Pb(Zr0.52Ti0.48)O3–Ni0.8Zn0.2Fe2O4 (PZT–NZFO) multilayered thin films with various volume fractions of the PZT phase (100, 74, 58, 48, 33, and 0%) were prepared on Pt/Ti/SiO2/Si substrates using sol–gel spin-coating method. X-ray diffraction shows polycrystalline structure and scanning electron microscopy reveals good multilayer morphology of the composite thin film as annealed at 700 °C in air. The thickness of the composite films was estimated in the range of ~400 to ~600 nm. The ferroelectric and magnetic properties were measured as function of the volume fractions of the PZT phase. The magnetoelectric (ME) effect was investigated under various bias magnetic fields. The maximum ME voltage coefficient (αE = dE/dH) is 278 mV/cmOe for the composite film with the volume fractions of the PZT phase of ~48%.

Magnetoelectric properties of CoFe2O4–Pb(Zr0.52Ti0.48)O3 multilayered composite film via sol–gel method

CoFe2O4–Pb(Zr0.52Ti0.48)O3 (CFO–PZT) multilayered composite film was prepared on Pt/Ti/SiO2/Si substrate via a sol–gel method and spin-coating technique. Results show that PZT and CFO phases exist in the composite film, calcined at 700 °C, besides substrate phase, and no obvious impurity phases can be detected. The composite film exhibits layered structure with obvious boundary between CFO and PZT films. Ferroelectric and ferromagnetic properties were simultaneously observed in the composite film, evidencing the ferroelectric and ferromagnetic properties in the composite film. The composite film exhibits both good magnetic and electric properties, as well as, magnetoelectric (ME) effect. The saturation magnetization value of the composite film is lower than that of the pure CFO film derived by the same processing as a result of the effect of the nonferromagnetic PZT layers. Ferroelectric hysteresis loops reveal that saturated polarization and remanent polarization of the composite film are lower than those of the pure PZT films. The composite film exhibits a very large ME effect, which makes the composite film attractive for technological applications as devices.

Role of TiO2 Seed Layer Thickness on the Nanostructure Evolution and Phase Transformation Behavior of Sputtered PZT Thin Films During Post‐Deposition Air‐Annealing

An optimum TiO2 seed layer is said to facilitate nucleation and subsequent growth of perovskite phase in Pb(Zr,Ti)O3 (PZT) films during annealing. The actual causes that prevent perovskite growth, particularly in sputtered PZT films on thick TiO2 seed layers are not yet understood clearly. Herein, based on the results of X‐ray diffractometry (XRD), field‐emission scanning electron microscopy (FESEM), and analytical scanning/transmission electron microscopy (S/TEM) with semi‐quantitative elemental mapping using energy dispersive X‐ray (EDX) spectrum imaging, the post‐annealing crystallization trend of r.f. magnetron sputter‐deposited amorphous PZT films has been scrutinized as a function of TiO2 seed layer thickness. Upon annealing, PZT films on thin TiO2 layers (~20–100 nm) partially crystallize into perovskite PZT via a transient pyrochlore/fluorite phase. However, no perovskite phase forms on thicker (~550 nm) TiO2 layer. Thickness of underlying TiO2 seed layer strongly influences the crystallization, phase formation, texture, and surface morphology of the PZT films. During crystallization, Pb diffuses away from the PZT film to form solid solution with TiO2 seed layer. Perovskite PZT phase transformation requires a minimum Pb‐concentration within the transient pyrochlore/fluorite phase. During the growth of perovskite grains, Zr gets segregated, resulting in Zr‐concentration build‐up within the surrounding disordered fcc fluorite phase.

Fabrication and magnetic properties of composite Ni0.5Zn0.5Fe2O4/Pb(Zr0.52Ti0.48)O3 nanofibers by electrospinning

One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems. In this work, the composite Ni0.5Zn0.5Fe2O4(NZFO)/Pb(Zr0.52Ti0.48)O3(PZT) nanofibers with average diameters about 65 nm are prepared by electrospinning from poly(vinyl pyrrolidone) (PVP) and metal salts. The precursor composite NZFO/PZT/PVP nanofibers and the subsequent calcined NZFO/PZT nanofibers are investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM).The magnetic properties for nanofibers are measured by vibrating sample magnetometer(VSM). The NZFO/PZT nanofibers obtained at calcination temperature of 900 °C for 2 h consist of the ferromagnetic spinel NZFO and ferroelectric perovskite PZT phases, which are constructed from about 37 nm NZFO and 17 nm PZT grains. The saturation magnetization of these NZFO/PZT nanofibers increases with increasing calcination temperature and contents of NZFO in the composite.

Preparation and characterisation of PZT films by RF-magnetron sputtering

Stoichiometric films were prepared by rf-magnetron sputtering from a Pb(Zr 0.54Ti 0.46)O 3 ceramic target onto Au-electroded substrates of alumina. During deposition the substrate holder was kept at a temperature of 300 °C. Post-deposition heat treatment in air at 650 °C was carried to promote the full crystallization and to result in pure perovskite PZT phase. SEM–EDX measurements for the films were performed both on surface and on cross-section. The impedance spectroscopy data demonstrates that the films have rather good dielectric properties and low losses. The recorded P–E loops prove their macroscopic ferroelectric characteristics, while piezoresponse force microscopy experiments confirm a nanoscale switching mechanism based on domain nucleation-growth.

Deposition of PZT thin film onto copper-coated polymer films by mean of pulsed-DC and RF-reactive sputtering

In this work, Pb(Zr,Ti)O3 (PZT) thin films were deposited onto flexible Cu-coated Kapton® substrates by means of reactive magnetron sputtering for the first time. Different power supplies were selected for each of the 200mm targets to adjust film composition and substrate ion bombardment. High-power pulse sputtering has been employed for the Zr-target to enhance for formation of nanocrystals, pulsed DC sputtering for the Ti-target to provide a high enough sputter yield, and RF-sputtering for the Pb-target to prevent droplet formation. The deposited films had a lead-enriched layer at the surface and their film composition was in rhombohedral range near the morphotropic phase boundary of the PZT phase diagram. XRD revealed a nanocrystallite mixture of lead, zirconium and titanium oxides in the as-deposited films which can be transferred into perovskite Pb(Zr,Ti)O3 by rapid temperature annealing. Observed piezoelectric properties demonstrate that rapid-temperature-annealed films are promising for application in flexible piezoelectric sensors, actuators and power generators.

Synthesis and characterization of Pb(Zr 0.5Ti 0.5)O 3 nanofibers

Pb(Zr 0.5Ti 0.5)O 3 (PZT) piezoelectric ceramic fibers were prepared by using electrospun PZT/poly(vinyl acetate) (PVAc) composite fibers by calcination for 1 h at the temperature range of 500 °C–700 °C in air. The morphology and crystal structure of calcined PZT nanofibers were characterized as a function of calcination temperature with an aid of XRD, FT-IR, SEM, and TEM. XRD and FT-IR results revealed that pyrochlore phase began to appear after calcination at 500 °C. For the fibers calcined at 550–600 °C, the dominant phase of tetragonal perovskite PZT with a weak pyrochlore phase was detected. The pyrochlore and tetragonal perovskite phases coexisted for the fibers calcined at 650–700 °C. The morphology of the fibers has changed from a smooth and uniform fiber to a porous fiber with increasing the temperature. The optimized fibers with a diameter of 334 nm were obtained when the fibers were calcined at 550 °C.

SYNTHESIS OF CoFe2O4/Pb(Zr0.53Ti0.47)O3 MULTIFERROIC COMPOSITE THICK FILMS BY LOW-SINTERING-TEMPERATURE SCREEN PRINTING METHOD

CoFe 2 O 4/ Pb ( Zr 0.53 Ti 0.47) O 3 (abbreviated as CFO/PZT) multiferroic composite thick films were successfully fabricated on alumina substrate with gold bottom electrode by screen printing method at a low-sintering temperature. The processing included the modification and dispersion of ferromagnetic CFO powder and ferroelectric PZT powder, the preparation of uniform pastes, and the selection of proper annealing temperature for composite thick films. Transmission electron microscopic pictures (TEM) indicated the submicron meter of particles size for both CFO and PZT particles. After annealing at 900°C for 1 h in air, tape test confirmed the quality of multiferroic thick films as well as pure CFO and PZT films. X-ray diffraction (XRD) showed a coexistence of CFO and PZT phases; furthermore, a smooth surface was observed through scanning electron microscopic (SEM) pictures along with the sharp cross-sectional picture, indicative of 100 μm of film thickness. Ferromagnetic and ferroelectric properties were observed in CFO/PZT films simultaneously at room temperature. Compared with the reported CFO/PZT multiferrroic thin films, the present ferromagnetic property was closing to that of the chemical sol-gel synthesized film and even that from the physical pulsed laser deposition technique. However, the ferroelectric property showed a degenerated behavior, possible reasons for this was discussed and further optimization was also proposed for the potential multifunctional application.