Lead Zirconate Titanate Solid Solution Research Articles

Synthesis and characterization of PZT 52/48 ceramics without additives througt nanomertric powder

ABSTRACT Lead zirconatetitanate solid solutions, Pb(Zr1-xTix)O3 – PZT, are widely recognized for representing a special group of ferroelectric materials with various potential applications in electroceramics and (micro)electronic devices. The PZT ceramics is produced by solid state reaction (conventional route) and temperatures frequently above 1200 °C. As a consequence, the cost of ceramic product is expensive. Herein, we present the synthesis and processing conditions of PZT52/48 (x = 0.48) ceramics in which it was possible to lower the sintering temperature down to around 900°C. We have applied a route for PZT52/48 obtaining ferroelectric ceramics through sintering of nanometric powders prepared by the polymeric precursor synthesis method (modified Pechini’s method). The sintering was achieved with a temperature of 900ºC for 2 hours and the samples got 96% of their theoretical density and 1.3 mm mean grain size. The electrical permittivity of the ceramic plates, studied by impedance spectroscopy, presented Curie temperature around 390 ºC. Ferroelectric hysteresis measurements revealed that the remnant polarization is 3.2 μC/cm2 and coercive field is 10 kV/cm at 60 Hz. All results and characterizations have shown that the PZT samples obtained with the polymeric route are efficient as the ones prepared in the conventional SSR protocol.

Investigation of the frequency dependence of the electrical conductivity in PZT piezoceramics

Purpose. To investigate the frequency dependence of the electrical conductivity in piezoelectric ceramics based on solid solutions of lead-zirconate titanate oxides.Methodology. To obtain the frequency dependence of the electrical conductivity in piezoelectric ceramics based on solid solutions of lead-zirconate titanate oxides, we used a technique for measuring the resistance of a sample with electrodes deposited on its opposite faces. Using the obtained resistance value, the value of the electrical conductivity of the sample was calculated at various frequencies.Findings. The frequency dependence of the specific electrical conductivity in PZT-22 piezoceramics based on solid solutions of lead-zirconate titanate oxides in the frequency range of 0 < ν < 60 kHz has been obtained by the authors. The specific electrical conductivity in PZT-22 piezoceramics increased over the entire range of frequencies studied. A sharp increase in specific electrical conductivity was observed at frequencies up to 20 kHz. At frequencies of ν > 20 kHz the increase in specific electrical conductivity ceased and at frequencies of ν > 30 kHz its value reached saturation. The maximum value of specific electrical conductivity γ = 0.55 . 10-6 Ohm-1.m-1 was obtained at a frequency of 60 kHz. The frequency dependence of the specific electrical conductivity in PZT-22 piezoceramics in the frequency range of 0 < ν < 60 kHz is analyzed. It was found that the specific electrical conductivity in PZT-22 piezoceramics increases according to a power law in the frequency range of 0 < ν < 10 kHz. The mechanism of changing the electrical conductivity in PZT piezoceramics with increasing frequency of the electric field is discussed. A formula is obtained that satisfactorily describes the experimental dependence of the specific electrical conductivity in PZT-22 piezoceramics on the frequency of an alternating voltage in the frequency range of 0 < ν < 10 kHz and which corresponds to the power law of A. Ioncher. The specific electrical conductivity in the unpolarized PZT-19 piezoceramics increases in the frequency range of 0 < ν < 100 kHz. In the frequency range of 0 < ν < 20 kHz a power law dependence is observed and at frequencies of ν > 20 kHz a power law is violated and the specific electrical conductivity gradually increases without reaching saturation. Originality. The frequency dependence of the electrical conductivity in PZT-22 piezoceramics in the frequency range of 0 < ν < 60 kHz is studied. It is established that the specific electrical conductivity in PZT-22 piezoceramics increases with increasing frequency of the electric field and in the frequency range of 0 < ν < 10 kHz, the nature of its change corresponds to the power law of A. Ioncher. The mechanism of change in electrical conductivity is due to the hopping conductivity of ions and polarons in a dielectric and is explained by the delay of slow polarization mechanisms. The nature of the dependence of the specific electrical conductivity in PZT-19 piezoelectric ceramics is due to the fact that polarization processes do not make a noticeable contribution to the dispersion of the electrical conductivity of unpolarized piezoceramics and the delay of slow polarization mechanisms is not observed.Practical value. When using piezoceramics based on solid solutions of lead-zirconate titanate oxides, it is necessary to take into account the significant dependence of its electrical conductivity on the frequency of an alternating electric field. The research results can be used to study the mechanism of electrical conductivity of piezoceramic materials based on solid solutions of lead-zirconate titanate oxides, which are used in electrical and electronic products under the influence of alternating electric fields of various frequencies.

Pre-transitional evolution of central peaks and transverse acoustic phonon branch in single crystal lead zirconate titanate with Ti concentration 0.7%

Inelastic X-ray scattering measurements have been done to study the lattice dynamics in lead zirconate titanate solid solution with 0.7% of PbTiO3. The temperature evolution of central peak and low-energy transverse phonon branches has been traced. Temperature dependent in-plane transverse polarized acoustic phonon branch in <1 1 0> direction has been revealed. The central peaks of two types have been found. The central peak at small wave vectors can be attributed to the relaxational-type soft ferroelectric mode, while the latter at Q = (1.5 -0.5 0) could be linked to the formation of M-superstructure in the intermediate ferroelectric phase.

Dynamic pyroelectric response of composite based on ferroelectric copolymer of poly(vinylidene fluoride-trifluoroethylene) and ferroelectric ceramics of barium lead zirconate titanate

In this work, pyroelectric properties of composite films on the basis of poly(vinylidene fluoride-trifluoroethylene) copolymer with a various level of ferroelectric ceramics inclusions of barium lead zirconate titanate solid solution were investigated by the dynamic method. The composite films were prepared by the solvent cast method. The unusual spike-like dynamic response with a quasi-stationary component was observed. It is supposed that composite films may be effectively used for pyroelectric applications.

Optical and Photoelectrochemical Properties of Lead Zirconate Titanate Thin Films Obtained by the Sol-Gel Method

We obtained optically transparent n-type semiconductor fi lms of lead zirconate titanate Pb(ZrxTi1-x)O3 by reaction of individual sols of hydrated titanium dioxide and zirconium dioxide with lead ions, followed by heat treatment at 500- 800°C. We established that these fi lms, when in contact with an aqueous electrolyte, can generate a photopotential and a photocurrent when exposed to UV radiation (250-400 nm). The average values of the bandgap energy from optical absorption and photocurrent spectroscopy data are slightly dependent on the composition of the lead zirconate titanate solid solution (they increase by 0.07-0.12 eV on going from Pb(Zr0.2Ti0.8)O3 to Pb(Zr0.52Ti0.48)O3), which may be connected with features of the band structure in these materials. Introduction. Lead zirconate titanate Pb(ZrxTi1-x)O3 (LZT) is a ferroelectric having pronounced piezoelectric, pyroelectric, nonlinear optical, and other functional properties, which is why it is promising for use in nonvolatile memory systems, electro-optical and acousto-optical devices, capacitors, and various types of sensors (1). A classical method for obtaining LZT in the form of thin (0.1-1 o m) fi lms (2-5), thick (5-200 o m) layers (6-9), or powder (9-13) is the sol-gel process for synthesis of a PbTiO3-PbZrO3 solid solution, enabling achievement of high purity and homogeneity of the material at relatively low temperatures. In the sol-gel process, the following have been used as precursors: lead acetate, tetrabutyl or tetrapropyl zirconate, and also tetrapropyl or tetrabutyl titanate (2-13) with addition of hydrolysis control agents and structure-forming agents: 2-methoxyethanol (2-4, 7, 8, 12), 1,1,1-tris(hydroxymethyl)ethane (10), diethanolamine (11), and acetylacetone (13). During sol-gel synthesis, hydrated titanium and zirconium oxides were generally formed by co- hydrolysis of organozirconium and organotitanium compounds. Of course, for subsequent removal of the organic molecules used in all the stages of the sol-gel synthesis, heat treatment is needed at a rather high temperature in an oxidizing atmosphere under conditions ruling out the possibility of encapsulation of the decomposition products of these compounds (in particular, elemental carbon) within the interior of the LZT fi lm. With the aim of minimizing the negative effect of the thermal decomposition products of the organic impurities on the quality of LZT fi lms, in this study we synthesized LZT by obtaining individual sols of hydrated titanium and zirconium dioxide from inorganic precursors, followed by reaction of these sols in a solution containing lead ions. In this case, it is possible to separately optimize the sol synthesis processes (especially using the pH of the hydrolysis process) and to use the cheaper inorganic salts (titanium tetrachloride and zirconyl nitrate) to synthesize them rather than alkoxide compounds of titanium and zirconium. The quality of the LZT fi lms obtained in this way was tested using their optical and photoelectrochemical properties. One of the tasks of this work was to determine the bandgap width for the LZT fi lms. Despite the large number of papers in which the bandgap width of LZT has been determined both from the optical transmission and refl ection spectra and from ellipsometric and photoelectric data (14-19), these values vary over rather a broad range: from 3.07 to 4.40 eV. With the aim of refi ning data on the bandgap width of LZT fi lms, we used a combination of the conventional method of

Field and Frequency Dependence of the Dynamic Hysteresis in Lead Zirconate Titanate Solid Solutions

Dynamic hysteresis of Nb‐doped Pb(Zr1−xTix)O3 (PZT, 0.20 ≤ x ≤ 0.60) ceramics were studied systemically at different field (E) and frequency (f). The hysteresis loops were strongly dependent on E and f. The measured coercive fields (Ec0) were far lower than the calculated values based on the Landau–Ginzburg theory, and increased dramatically from the rhombohedral phase to the tetragonal phase while had less variation with composition in the same phase. With increasing E or f for each composition, three types of loops were observed: linear, minor, and saturated loops. The cross fields (E0), cross polarizations (P0), and hysteresis areas (&lt;A&gt;) showed different variation regularities with f. Similar varying curves were observed for all PZT ceramic samples by normalizing E0, P0, and &lt;A&gt; with E/Ec0, which indicated the same polarization switching for different domain structures. Further analyses revealed that the switching processes can be divided into three stages: space charge polarization, domain switching, and steady state. The first and second stage occurred at ~0.5 and ~1.5 E/Ec0, respectively. These results would be very helpful to further understand the polarization switching of ferroelectric ceramics.

The temperature effect on the resonant spectra of thin piezoelectric ceramic disk

This study examines the influence of the temperature on the low-frequency resonant spectrum of piezoelectric ceramics based on lead zirconate titanate solid solution Pb(Zr,Ti)O3-based piezoelectric ceramics with heat variations ranging from 25 to 150°C, concluding that temperature increases cause the resonant spectrum to shift to higher frequencies. Furthermore, the variation in fundamental series resonant frequency fs (with temperature variation) is larger than the variation of fundamental parallel resonant frequency fp (with temperature variation). Another result of increased temperature is the decrease in effective electromechanical coupling factor keff. Finally, the effect of temperature on the overtone mode is more obvious than that of the fundamental mode.

Ferroelectric Domain Structure of PZT Tetragonal Single Crystals Analysed by Scanning Probe Microscopy

AbstractFrom the application point of view, the most interesting compositions in the lead zirconate titanate solid solutions, PbZrxTi1-xO3 (PZT), are those near the centre of the phase diagram, where tetragonal and rhombohedral phases are separated by a boundary nearly independent on temperature. The composition of this so-called morphotropic phase boundary (MPB) is approximately 52/48 at room temperature. The piezoelectric coefficients, electromechanical coupling coefficients, dielectric permittivity and remnant polarization measured on ceramic samples reach a maximum in this region, not necessarily at the same composition, which explains why these compositions are technologically so interesting.

Peculiarities of Ferro-Antiferroelectric Phase Transitions 8. Long-Time Relaxation Processes

The study of the kinetics of mezoscopic segregations in the vicinity of interphase domain boundaries separating the domains of the coexisting ferroelectric and antiferroelectric phases in two series of the lead zirconate titanate based solid solutions is presented. The investigated lead zirconate titanate solid solutions in which the isovalent complex (La 0.5 Li 0.5 ) 2 + or the La 3 + ions are substituted for lead possess an extended region of coexistence of the ferroelectric and antiferroelectric phases. The mechanisms that control the kinetics of formation of the segregates are investigated and compared for these two series of solid solutions.

Preparation of piezoelectric 0.1Pb(Zn 0.5W 0.5)O 3–0.9Pb(Zr 0.5Ti 0.5)O 3 solid solution and thick films for low temperature firing on a Si-substrate

A newly designed lead zirconate titanate (PZT) solid solution 0.1Pb(Zn 0.5W 0.5)O 3–0.9Pb(Zr 0.5Ti 0.5)O 3 was prepared. It is feasible for a low temperature firing. X-ray diffraction shows that its structure is a single perovskite phase, and its thick films were successfully fabricated on a Pt/TiO 2/SiN x /Si-substrate through the screen printing method. A conventional screen printing thick film and a hybrid thick film (screen printing and PZT sol infiltration) was also compared. According to an SEM study, the prepared thick film showed a much denser microstructure with the sol infiltration method. The electrical properties of the prepared PZT solid solution and its thick film were predominantly realized in a low temperature region. The dielectric constant of a conventional screen printing thick film and the hybrid thick film (sintered at 900 °C), was 703.5 and 911.3, respectively.

Thermal properties of PZT-based ferroelectric ceramics

The thermal properties of piezoelectric ceramics (PKR-8, PKR-7M) based on lead zirconate titanate solid solutions Pb(Ti, Zr)O3 were studied over the temperature range 300–800 K. The thermal conductivity and thermal expansion coefficients were found to exhibit an anomalous behavior in the region of the ferroelectric phase transition.

Structural and electrical properties of nanocrystalline PLZT ceramics synthesized via mechanochemical processing

Nanocrystalline powders of La-modified lead zirconate titanate (PLZT: 7/60/40) solid solution have been synthesized via mechanochemical processing. No excess PbO was used in the starting composition. Scanning and transmission electron microscopy revealed the formation of powders on the nano-scale. Sintering the powders resulted in dense compacts, at reduced sintering temperatures. Well-saturated ferroelectric hysteresis loops with a Pr on the order of ∼48 µC cm−2 and coercive fields of ∼7 kV cm−1 were recorded on the samples. Strain levels up to > 0.25% with limited hysteresis (<0.05% in the low field region) indicate the tremendous potential of these ceramics for high-performance actuators, especially in cases where a high degree of positioning accuracy is required.

Phase coexistence near the morphotropic phase boundary in lead zirconate titanate (PbZrO3-PbTiO3) solid solutions

An equilibrium phase diagram satisfying the Gibbs phase rule is computed for the PbZrO3-PbTiO3 (PZT) system from a low-order Landau expansion in the approximation of the theory of regular solutions. We show that in the equilibrium phase diagram, miscibility gaps replace the morphotropic phase boundary and the paraelectric to ferroelectric transition lines of the “diffusionless” phase diagram. The decomposition occurs by a peritectoid reaction and the miscibility gaps expand significantly with increasing positive values of the atomic exchange interaction parameter. Diffusional processes are estimated to be sufficiently fast to achieve two-phase equilibria at normal rates of cooling used to process PZT materials.

Synthesis of barium titanate–lead zirconate titanate solid solutions by a modified mixed-oxide synthetic route

Abstract Phase formation characteristics of perovskite powders in the (1− x )Pb(Zr 0.52 Ti 0.48 )O 3 – x BaTiO 3 , (1− x )PZT– x BT system prepared by a modified mixed-oxide synthetic route have been investigated by varying the chemical compositions and calcination temperatures. Lattice parameter changes were examined as a function of composition. It was seen that complete solid solutions of perovskite-like phase in the (1− x )PZT– x BT system was obtained. With increasing BT content, the cell parameters and the degree of tetragonality decreased, while optimum firing temperatures increased continuously.

Study on the relation between the dielectric properties and lattice distortions in PZT ferroelectric tetragonal phase region

From thermodynamic theory of the lead zirconatetitanate(PZT) solid solution sy stem, we have got the basic equation between the dielectric constant εr a nd lattice distortion c/a in ferroelectric tetragonal phase region, and base d on the relative experimental data and logical deduction to physics image, we h ave established basic relations between εr and c/a. And then, from th e basic relations, we have studied in detail the physics image about lattice dis tortion c/a effect on the dielectric constant εr in ferroelectric tet ragonal phase region. A comparison with related experimental results indicates t hat the results of the basic relations are in good agreement with the conclusion s of the experiments. Finally, we have discussed the application range of the ba sic relations and the physics reason of relative warp out of application range. We would emphasize that the basic relations are essentially fitted to all perovs kite structure materials.

Fractal Dimensionalities and Microstructure Parameters of Piezoceramic PZTNB-1

The microstructure of PZTNB-1 piezoceramics (the lead zirconate-titanate solid solutions doped with sodium and bismuth) has been studied for small variation of Ti/Zr ratio near the morphotropic boundary in comparison with the tetragonal PZT-19. The size distribution of grains and porous, their shape peculiarities were revealed with using computer treatment of visualized structural elements. The fractality of the microstructure were revealed and fractal dimensionalities were calculated.

Peculiarities of Large-Grained Lead Zirconate-Titanate Solid Solutions in the Vicinity of Morphotropic Phase Region

(Pb0.9Ba0.05Sr0.05)(Zr1−xTix)O3 solid solutions series in which the width of the morphotropic region (MR) (determined by X-ray structure analysis) does not exceed 0.5%, are obtained using a modified ceramic technique. The grain size of the ceramics is 20–25 μm. As established by the performed investigations, piezoelectric and dielectric properties of ceramic samples and diffusion of PE phase transition depends on the position of the given solid solution in the phase diagram. The maximum diffusion is observed in the middle of MR. There exists a temperature range ΔTcf of the order of several decades of degrees above the Curie point, where piezoelectric resonance can be observed. ΔTcf value reduces considerably when moving from MR.

Vibrations of the Crystal Lattice of Solid Solutions of Lead Zirconate-Titanate

The IR spectra of samples of solid solutions of lead zirconate-titanate with a rhombohedral and a tetragonal structures have been investigated. The frequencies of the vibrational modes of pairs or groups of atoms bound together have been determined in relation to the composition of the solid solutions. It has been established that in the case of lead zirconate-titanate with the rhombohedral structure, the modes with frequencies 150–250 and 450–600 cm−1 are dependent on the ratio between the atoms of zirconium and titanium in the crystal lattice cell. It is shown that with increase in the content of lead titanate in solid solutions of lead zirconate-titanate with a tetragonal structure, the frequency of the ferroelectric-active mode shifts toward higher frequencies.

Field-enhanced piezoelectric deformation during the high temperature/low temperature rhombohedral (FERh/FERL) phase transformation for tin modified lead zirconate titanate ceramics

An unusual field-enhanced piezoelectric deformation near the FERH/FERL structural phase transformation was observed in a tin modified lead zirconate titanate solid solution. In addition to the typical field-induced domain reorientation and the piezoelectric strain, this additional field-enhanced deformation only observed near the phase transformation increases linearly with external electric field strength. A 78% increase in field-enhanced strain was observed at a field strength of 32 kV/cm. Comparison of the dielectric susceptibility at low and high field conditions suggests that the observed unusual behavior is created by a field-induced lattice softening during the structural phase transformation. Experimental observations on the field-induced softening phenomena are reported.

Phase coexistence in lead zirconate titanate solid solutions

This paper discusses the phenomena observed in the vicinity of the morphotropic phase boundary in Pb(Ti1−xZrx)O3 (PZT) solid solutions. The location of the boundary between the stable tetragonal ferroelectric phase and the stable rhombohedral ferroelectric phase is calculated, and an analytical expression for determining the concentration range of the possible coexistence of these phases is derived. According to the numerical estimates, the concentration range can be as much as 20 mol % lead zirconate. However, reliable experimental data in support of these estimates are as yet unavailable.