Lead Zirconate Titanate Ceramics Research Articles

In situ XRD analyses for asymmetric responses of poled PLZT ceramics during electric fatigue

Electric fatigue behaviors of the poled lanthanum-doped lead zirconate titanate (PLZT) ceramics were investigated using a home-made electric loading apparatus in conjunction with a conventional X-ray diffractometer. The XRD data were measured under actions of the applied direct current electric fields on the as-received poled PLZT specimens being experienced various cycles (10N) of alternating current (AC) electric fields. Experimental data showed that in addition to apparent degradation in remnant polarization, asymmetries in hysteresis loops and fraction of 90° domain switching curves were observed. It was found that an offset electrical field (\(\Delta {{\text{E}}_N}\)) was induced in the poled specimen by polarization with its direction against the direction of the polarization. Furthermore, the magnitude of \(\Delta {{\text{E}}_N}\) and the degree of asymmetry (δN) decreased as the number of AC electric fatigue cycles (10N) varied from 100 to 106. In situ XRD data suggested that the poled specimen exhibited different abilities to reorient a-domains into c-domains when the applied electric fields were opposite. The δN not only depended linearly on \(\Delta {{\text{E}}_N}\), but also on abilities of the poled specimen to reorient a-domains into c-domains.

Mechanically induced ferroelectric domain evolution during crack propagation

Ferroelectric switching near the crack tip in lead zirconate titanate ceramics leads to a change of both polarization and remanent strain, which affects substantially the stress field and fracture behavior. In particular, for tetragonal crystals the 90° domain reorientation is believed to enhance fracture toughness of the damaged piezoelectric ceramics. Current research models evolution of the domain reorientation processes during crack propagation by a micromechanical model using finite element analysis. The crack growth is numerically simulated by means of electromechanical cohesive elements along the prospective crack path. The study of these irreversible dissipative mechanisms makes the main subject of our numerical investigations. The computed 3D scattering of domain orientations in a mechanically loaded PZT-PIC151 CT-specimen is compared with in situ x-ray diffraction experiments in synchrotron (Jones et al 2007 Acta Mater. 55, 5538–5548). It is found that the preferred orientation and intensity of domain distribution in the mechanically loaded specimen depend on the in-plane position and are related to the projected deviatoric stresses/strains. In contrast to simulations with a fixed crack tip (Kozinov and Kuna 2018 Arch. Appl. Mech.), during crack propagation the maximal tensile stresses and region of highest intensity of domain reorientation are moved with the crack tip and smeared over a process zone. While the crack length increases, the domain switching belt causes a shielding effect leading to an apparent materials toughening. Such fully coupled, three-dimensional simulation of crack growth resistance curves is the first one in ferroelectrics.

Tensile Piezoelectric Actuator: Fabrication, Characterization and Application

A multilayer piezoelectric actuator, with dimension of 10 mm×10 mm×60 mm, which can output a tensile displacement directly by exploring the d31 effect of piezoelectrics, was fabricated using soft Lead Zirconate Titanate (PZT) ceramics. The performance of the actuator was characterized by a special home-made experimental setup under electric fields varying from 200 to 1 000 V/mm with the preload varying from -150 to 100 N at room temperature. Results showed that it can output a maximum tensile displacement of 12 μm under unipolar electric field of 1 000 V/mm and preload was independent with generative displacement in the range of testing preload. Additionally, using the actuator, we built a micro loading apparatus, which can be used to test the fracture behavior of brittle materials.

Electric behaviour of soft and hard lead zirconate titanate ceramics under electromechanical loading

ABSTRACTThe influence of uniaxial pressure (0 –1100 bars) applied parallel to the ac and dc electric field on the dielectric and ferroelectric properties of soft and hard PZT ceramics was studied in the temperature range from room temperature to 500°C. The results show that applying uniaxial pressure leads to a reduction of the peak intensity of the electric permittivity (ε) and its frequency dispersion. The peak intensity of ε becomes diffused and shifts with increasing pressure. The effective electric field Eeff and electrostrictive coefficient Q11 were evaluated from the obtained data. We explained our results based on the Cochran soft-mode, dielectric relaxation and a combination of de-aging and domain resulting processes from pressure.

Flash sintering of lead zirconate titanate ceramics under an alternating current electrical field

Sintering behaviors of lead zirconate titanate ceramics under an alternating current (AC) electrical field with a frequency of 60 Hz is investigated. The AC field is more effective to induce flash sintering compared to the direct current (DC) field. The AC field strength shows a negative correlation with the flash sintering temperature and grain size of sample. The large current limit causes the severe current and temperature localization, leading to the non-uniform sintering. The flash sintered samples have high d33 values. The mechanisms of flash sintering are discussed in terms of Joule heating and formation of defects.

Photostriction properties of PLZT (4/52/48) ceramics sintered by SPS

In this paper, the preparation and sintering process of Lanthanum-modified lead zirconate titanate ceramics (PLZT 4/52/48) powders and ceramics were investigated. The PLZT powders were prepared by co-precipitation and sol-gel methods. It is confirmed that PLZT powders synthesized by sol-gel method had smaller grains and better dispersion. The atmosphere sintering and spark plasma sintering（SPS）technique were used to sinter the PLZT ceramics separately. After sintering, the physical, electrical, and optical properties of the PLZT ceramics sintered by different methods were tested. The results show that the SPS sintering can increase the densification degree (reaching 99.5%)of the PLZT ceramics, which improved the transparency, ferroelectric, piezoelectric and optical properties of PLZT ceramics. It is found that when the light intensity reached 600 mW/cm2, the maximum photo-induced strain of the SPS sintered ceramic was as high as 10. 84 × 10−3, which was almost 1.4 times larger than that of the atmosphere-sintered sample. Obviously, the sol-gel method and SPS process can enhance the comprehensive performance of PLZT ceramics.

Micromechanical simulation of ferroelectric domain processes at crack tips

The electromechanical loading situation at cracks in ferroelectric ceramics is essentially affected by domain switching. Under high electrical and/or mechanical external fields, the state of polarization and remanent strains is substantially changed at the crack tip. These irreversible dissipative processes influence the fracture toughness of the cracked ferroelectric material. In the present paper, the micromechanical domain switching processes at the crack tip are studied by numerical simulation and compared with the in situ experimental results obtained by Jones et al. (Acta Mater 55(16):5538–5548, 2007) using X-ray diffraction analyses in synchrotron. Main attention is payed to the spatial distribution of preferred domain orientation in a mechanically loaded compact tension specimen made of a soft tetragonal lead zirconate titanate ceramics. It is found that the mechanically induced favored domain orientation distribution depends on position within the plane of the CT specimen and correlates with projected deviatoric stresses and strains. Some issues concerning shortcomings in the experimental and simulation results are raised and discussed. The outcome of this type of simulations forms the basis for more realistic fracture mechanical evaluations in future.

Infrared and Structural Studies of Micro and Nano-crystalline Ta Doped Lead Zirconate Titanate Ceramics

<p> In this paper, influence of additives on structural properties of Tantalum (<em>Ta</em>) doped PZT ceramics, prepared by solid-state oxide and mechanical activation (MA) routes, has been studied. The Fourier transformation infrared spectroscopy (FTIR) studies, are done to understand the structural interactions, confirmed that the wave number and bond energy decreases with the increase in Ta content accompanied by decrease in grain size. FTIR spectrum becomes broader in nanocrystalline Ta-PZT. The fraction of tetragonal phase decrease along with reduction in grain size as the <em>Ta </em>content increase. The remnant polarisation and coercive field also follows the similar trend on <em>Ta </em>doping. It is seen that infrared spectroscopy results corroborate the structure and ferroelectric properties of PZT materials.</p>

Evaluation of performance of polyamide/lead zirconate titanate composite for energy harvesters and actuators

By means of experimental tools, we have studied the effect of lead zirconate titanate volume fraction introduced in polyamide-6/lead zirconate titanate composites on dielectric, piezoelectric, mechanical, and structural properties. As the first result, we found that the insertion of lead zirconate titanate particles makes the dielectric permittivity of the polyamide-6 matrix increases from 10 to 95.8. The dielectric property studies reveal that under an electrical field of 1 kV the remnant polarization is also increased from 0.17 to 0.4, this behavior is related to both the increase of volume fraction of lead zirconate titanate from 20% to 40% and the piezoelectric coefficient changes proportionally with that of volume fraction of lead zirconate titanate. Furthermore, piezoelectric activity increases with lead zirconate titanate particle size at a range where there is a lower order of magnitude. Finally, the uniform dispersion of the ceramic lead zirconate titanate particles in polyamide matrix has been confirmed by scanning electron microscopy analysis. The performances reached by polyamide-6/lead zirconate titanate composites open new horizons for energy harvesting and actuators.

Large actuation strain over 0.3% in periodically orthogonal poled BaTiO3 ceramics and multilayer actuators via reversible domain switching

Lead titanate zirconate (PZT) ceramics based piezoelectric actuators always suffer from small output strains (typically 0.1%–0.15%) and have recently been criticized for the toxicity problem of the high-concentration lead. In our recent work (Li et al 2017 J. Appl. Phys. 122 074103), we realized large local actuation strain nearly 0.6% in a periodically orthogonal poled (POP) PZT ceramics via reversible domain switching. In this work, we applied the POP method to barium titanate (BT) ceramics and proposed a specially designed multilayer actuator which can output large uniform strain. The simple tetragonal structure of BT ceramics makes it easier to understand the mechanism of reversible domain switching in POP ceramics and its lead-free characteristic is more promising. Firstly, a POP BT ceramic piece was fabricated and the actuation testing results show that local large actuation strain of 0.36% can be obtained under a field of 2 kV mm−1 at 0.1 Hz. However, the actuation strain is non-uniform along the period direction, varying from 0.22% to 0.36%. Then, to output uniform large strain, a four-layer actuator based on the POP BT ceramics was designed and fabricated in which only the in-plane poled regions of the adjacent layers were bonded. Results show that the output strain turns to be uniform in this way, which is 0.34% under 2 kV mm−1, resulting in a very high large-signal (=Smax/Emax) of 1700 pm V−1. The large actuation strain is very stable and keeps unchanged after 20k cycles of operation. It drops quickly with the increasing frequency and is stabilized at 0.18% above 1.0 Hz. Finally, bipolar field testing was conducted on the POP BT based actuator. Results show that the actuator shows electrostriction-like symmetric bipolar actuation behavior with the repeatable actuation strain of 0.3% under 2 kV mm−1. This work may provide a feasible solution to low frequency, large-strain lead-free piezoelectric actuation.

Dielectric and Ferroelectric Properties of Rare Earth Doped Lead Zirconate Titanate Ceramics

We have synthesized La3+ and Sc3+ doped lead zirconate titanate electroceramics with the stoichiometric formula ( (PLZTS), where x = 0.1 and y = 0.2, 0.4, 0.6 & 0.8, by a conventional solid-state reaction method & investigated its structural, microstructural, dielectric, electrical and ferroelectric properties. X-ray diffractometry was used to probe the phase purity and to derive the crystallographic parameters. Furthermore, structural phase transition was investigated by analyzing Raman spectra recorded in the temperature window of 80-580 K. The size, shape, and the distribution of grains were examined through a scanning electron microscope (SEM) and the sample was subjected to energy dispersive spectroscopy (EDS) for elemental analysis. We have carried out dielectric and electrical measurements on Pt/PLZTS/Pt metal-ferroelectric-metal capacitors using impedance analyzer and electrometer, respectively, as a function of temperature (100-600 K) and frequency (102-106 Hz). High dielectric constants (ɛ’) ~280, ~500, ~1800 & 1000 for y = 0.2, 0.4, 0.6 & 0.8 respectively were observed at room temperature. We measured hysteresis loops which proved the existence of ferroelectricity in all prepared samples of different compositions. These results provide insights into PLZTS ferroelectric capacitor for its potential applications in the future electronic devices.

Flash sintering of lead zirconate titanate (PZT) ceramics: Influence of electrical field and current limit on densification and grain growth

Flash sintering of lead zirconate titanate ceramics were investigated under DC electric fields ranging from 300 to 600 V/cm. The onset temperature for flash sintering significantly decreased with the electrical field to a lower limit of furnace temperature of 538 °C at 600 V/cm. The retardation of grain growth was observed, and the grain size decreased with increasing the electrical field. The current limit had a great influence on the density and grain size of specimen. During the flash sintering process, power dissipation first rose abruptly to a maximum value, then declined sharply to a steady state. Meanwhile, optical glow of specimen was observed. Using black body radiation model, the actual specimen temperature was estimated, which was too low to obtain the full dense ceramics in 30 s. It was suggested that Joule heating, ultra-high heating rate and high concentrations of defects were responsible for flash sintering of PZT ceramics.

Effect of the Sintering Temperature on the Formation of Ferroelectric Properties of a Lead Zirconate–Titanate Ceramic

Effect of the sintering temperature on the formation of the microstructure, the domain structure, and the ferroelectric properties of a lead zirconate–titanate Pb(Ti x Zr1 – x)O3 piezoelectric ceramics has been studied. It is shown that the ferroelectric phase forms at a sintering temperature of 860°C. At higher sintering temperatures, the main effect on the properties is due to a unit cell deformation and free charge carriers.

Measurement of flow rate using straight pipes and pipe bends with integrated piezoelectric sensors

The original noninvasive method for measuring the flow rate of liquids proposed in this work relies on the ability of the piezoelectric sensors embedded into pipes or pipe bends to detect the pressure fluctuations of turbulent flow. As the pressure fluctuation is directly related to the flow velocity, the electric responses of the piezoelectric sensors are correlated to the flow rate. Plastic pipes and pipe bends of different curvature radius with embedded piezoelectric ceramics of lead zirconate titanate (PZT) were used for measuring the flow rate of water. The piezoelectric sensors are placed close to the inner surface of pipe to increase their sensitivity to the pressure fluctuations of turbulent flow. Measurements of pipe vibration with accelerometers were also performed for comparison purposes. Frequency domain analyses demonstrate that the response of the piezoelectric sensors is mainly related to the pressure fluctuation of turbulent flow. Preliminary results of tests with straight acrylic pipes and 90° pipe bends made of polyvinyl chloride (PVC) demonstrate the effectiveness of the proposed technique. An interesting sensing performance to flow was observed for the PZT sensors installed in bends of small curvature radius. The disturbances to flow generate high pressure fluctuations in short radius bends, consequently improving the sensitivity to flow rate of the PZT sensors. Volumetric flow rates lower than 0.1 l/s were detected using a 90° bend of r/d = 0.5, with inside diameter d = 21 mm and integrated PZT sensors. As the pressure fluctuation is responsible for the pipe bend vibration, the sensitivity to flow rate of the accelerometers was also significantly improved.

High power evaluation of textured piezoelectric ceramics for SONAR projectors

Textured Ceramics of the relaxor ferroelectric PMNT have shown exceptional piezoelectric properties suitable for high power SONAR projectors. The piezoelectric coefficient (d33>800pm/V), the electromechanical coupling coefficient (k33>0.80), and the mechanical quality factor (Qm>90) in various forms of PMNT showcase the potential for these textured ceramics to be implemented in a high power, broad bandwidth acoustic projector. This work attempted to devise a set of experiments to quickly characterize the electromechanical performance of these materials in relevant devices in order to provide feedback to both the material developers and the user community. In this effort, textured PMNT and Manganese doped PMNT (Mn:PMNT) were compared to the performance of conventional lead zirconate titanate (PZT) ceramics. Linearity and harmonic distortion measurements were made in a high pressure test facility to measure source levels of these SONAR projectors. In addition, isothermal measurements were made at 50 degrees Celsius to monitor source levels as a function of duty cycle. The results from these measurements were then compared to modeled results and appropriate recommendations on material composition improvements were made.

Effect of Gd on dielectric and piezoelectric properties of lead zirconate titanate ferroelectric ceramics

ABSTRACTIn view of the importance of rare – earth modified PZT, Gd-modified lead zirconate titanate (PGZT) ceramics with a general chemical formula Pb1-xGdx(Zr0.35Ti0.65)1-x/4O3 (x = 0, 0.07,0.10,0.12) near morphotropic phase boundary (MPB) have been prepared using high-temperature solid-state reaction route. The X-ray diffraction (XRD) study shows the formation of single phase rhombohedral structure for x 0.07 and tetragonal structure for x > 0.07 at room temperature. Dielectric properties (ϵr and tanδ) were studied as a function of temperature (25–500°C) at different frequencies (1–1000 kHz) exhibit a systematic change in dielectric constant, phase transition temperature and diffusivity. Results of detailed dielectric study indicate the diffuse phase transition at higher value of gadolinium concentration and non-relaxor behavior. The ac conductivity spectrum of PGZT/x/35/65 ceramics is found to obey Jonscher's Universal power law. The appearance of hysteresis loops below transition temperature supports the existence of ferroelectric properties in the studied compounds. The enhancement of remnant polarization (Pr) and piezoelectric constants (d33) was obtained with substitution of Gd for the PZT ceramics which can be used for multilayer capacitor, sensor and actuator applications.

High piezoelectric properties of modified nano lead titanate zirconate ceramics

A series of PbZrxTi1-xO3 (x = 0.0, 0.2, 0.4 and 0.8) nanoparticle samples were prepared by tartrate precursor method. Both the piezoelectric modulus d33 and the grain size increased by increasing zirconium (Zr) content up to x = 0.4 and then decreases for higher content. The coupling factor Kp increased also by more doping of Zr up to x = 0.4. The ultrasonic wave velocity decreased with increasing Zr content up to x = 0.4. The piezoelectric modulus d33 value of nano PbZr0.4Ti0.6O3 is suitable for improving application for piezoelectric technology.

Electronic and Optical Properties of Sodium Niobate: A Density Functional Theory Study

In recent years, much effort has been devoted to replace the most commonly used piezoelectric ceramic lead zirconate titanate Pb[ZrxTi1−x]O3 (PZT) with a suitable lead‐free alternative for memory or piezoelectric applications. One possible alternative to PZT is sodium niobate as it exhibits electrical and mechanical properties that make it an interesting material for technological applications. The high‐temperature simple cubic perovskite structure undergoes a series of structural phase transitions with decreasing temperature. However, particularly the phases at room temperature and below are not yet fully characterised and understood. Here, we perform density functional theory calculations for the possible phases at room temperature and below and report on the structural, electronic, and optical properties of the different phases in comparison to experimental findings.

Domain switching behavior in lead zirconate titanate piezoelectric ceramics

The domain switching behaviors of lead zirconate titanate ceramics were monitored via direct, in-situ lattice observation using transmission electron microscopy. The lattice structures were monitored via video as a sample was heated from room temperature to 300°C. The lattices vibrated in the [110] direction several times over a short period, e.g., 0.1s. Moreover, lattice sliding occurred in the [100] direction for about 15Å. Those lattice motions were detected at around 83–84°C. Lattice orientations were analyzed using the domain switching model to substantiate whether these movements can be attributed to domain switching.

Structural, dielectric and ferroelectric properties of rare earth substituted lead zirconate titanate

Rare-earth (RE) metal (Pr, Yb, Sm) ions doped lead zirconate titanate (PZT) ceramics were synthesized by the sol–gel auto-combustion technique and characterized for their structural, morphological and ferroelectric properties. The results from X-ray diffraction analysis of all these samples confirmed the tetragonal phase and only in the case of Sm doped PZT, there is pyrochlore phase. The surface morphology revealed a decrease in grain size with the RE doping with the lowest value for Yb–PZT. From the dielectric studies, a high value of dielectric constant of 2 × 105 was observed for Yb–PZT and drop in Curie temperature was observed for Pr and Sm doped PZT. The low dielectric loss and an increase in coercivity were found for Pr doped PZT which may have potential applications in memory devices.