Lead Zirconate Titanate Stannate Research Articles

New insights into suppression of intermediate incommensurate phase in lead zirconate stannate titanate antiferroelectric system

New insights into suppression of intermediate incommensurate phase in lead zirconate stannate titanate antiferroelectric system

Lead-based antiferroelectrics revisited for high energy density capacitors and large strain actuators

Lead zirconate stannate titanate (PZST) ceramics with the generic composition of Pb1-0.5xNbx[(ZrySn1-y)1-zTiz]1-xO3 with x representing Nb content (x = 0 or 0.02), y representing Zr:Sn ratio (y = 0.57 or 0.60), and z representing Ti content (z = 0.06 or 0.08), and lead lanthanum zirconate titanate (PLZT) ceramics with the general composition of Pb1-xLax(ZryTi1−y)1−x/4O3 with x = 0.050 − 0.120 were synthesized using solid state reaction method and sintering. The energy density and field induced strain behavior of these compositions were investigated for capacitor and actuator applications, respectively. The focus of the study was to evaluate and discuss the change in the polar state of these ceramics from normal ferroelectric to antiferroelectric to relaxor antiferroelectric to linear dielectric with compositional modification. The highest releasable energy density (1.053 J/cm3) was obtained from the antiferroelectric Pb[(Zr0.60Sn0.40)0.94Ti0.06]O3 composition among the PZST compositions that were investigated, but the efficiencies were generally low (max. 60%) due to the large hysteresis that was observed in these compositions. The highest field induced strain level of 0.26% was also measured in the same composition. In the case of PLZT compositions, the highest releasable energy density values (0.313 J/cm3) with much higher efficiencies (76%) and highest field induced strain levels (0.23%) were obtained from the PLZT compositions with relaxor antiferroelectric character.

Influence of Zr/Sn ratio on the Transverse Piezoelectric Coefficient in Lanthanum-Doped Lead Zirconate Titanate Stannate Thin Films

In this study, we report the effect of Zr/Sn ratio on the Antiferroelectric (AFE) → Ferroelectric (FE) phase transition and transverse piezoelectric characteristics on AFE thin films of compositions having the general formula Pb0.97La0.02(Zr1-x+ySnxTiy)O3, where y = 0.10 and 0.10 ≤ x ≤ 0.15 along the phase boundary in the ternary system Pb(Zr0.50Ti0.50)O3-Pb(Zr0.50Sn0.50)O3-PbZrO3. Thin films having a thickness of 2.0 µm were fabricated on platinised silicon substrates by sol–gel method. Data obtained from dielectric, ferroelectric and structural studies have been combined to explain the mechanism of AFE → FE switching.

Dielectric and ferroelectric properties of lanthanum‐modified lead zirconate stannate titanate (42/40/18) ceramics

AbstractThe effect of lanthanum (La) content on the phase transformation of Pb1−3x/2Lax(Zr0.42Sn0.40Ti0.18)O3 (PLZST 100x/42/40/18, 0 ≤ x ≤ 0.06) ceramics was investigated by the dielectric and ferroelectric properties. The base composition PLZST 0/42/40/18 located in the ferroelectric (FE) rhombohedral phase region. As x increased, the compositions showed successively FE and antiferroelectric (AFE) state at room temperature, and their peak temperatures (Tmax) decreased gradually in line as Tmax = 162.21‐1507x. Evidence was presented that there were two dielectric anomalies in PLZST 2/42/40/18, which were corresponding to the FE‐AFE and AFE‐paraelectric (PE) phase transformations, respectively. With increasing the dc bias fields, the two phases merged into one. PLZST 3/42/40/18 showed AFE characteristics with the first loop outside of the second loop and there was only one dielectric inflection. The critical lanthanum content occurred at x = 0.03 from the dielectric temperature spectra and hysteresis loops. Furthermore increase in La above 0.03, these compositions showed typical antiferroelectric behaviors with double hysteresis loops. The stored energy properties of the three compositions (PLZST 4/42/40/18, 5/42/40/18 and 6/42/40/18) displayed different temperature dependencies from room temperature to 140°C (over their respective Tmax). Comparing the above results with previous investigations on PLZSTs, some questions were discussed.

Barium content study and properties characterization of lead zirconate stannate titanate antiferroelectric ceramics using thermally stimulated depolarization current technique

Thermally stimulated depolarization current (TSDC) and highly accelerated lifetime testing studies of (Pb0.925-xLa0.05Bax)(Zr0.52Sn0.39Ti0.09)O3 (PLBZST) antiferroelectric ceramics have been performed for three compositions with different barium contents. These studies have revealed that barium substitution increases the failure time and improves the resistance degradation behavior. As a result of the variations of peak current intensity and peak temperature with different polarization temperatures in the TSDC curves, three successive relaxation peaks with different origins have been found to occur: a low-temperature defect dipole peak, an intermediate-temperature in-grain oxygen vacancy migration peak, and a high-temperature transgranular oxygen vacancy migration peak. These results demonstrate that the improved resistance degradation process with the increase of barium substitution is related to the decrease in oxygen vacancy concentration.

Low loss and high permittivity composites based on poly(vinylidene fluoride-chlorotrifluoroethylene) and lead lanthanum zirconate titanate

Lanthanum doped lead zirconate titanate stannate antiferroelectric ceramic (Pb0.97La0.02)(Zr0.63Sn0.3Ti0.07)O3 (PLZST) is proposed as an inorganic filler. P(VDF-CTFE)/PLZST composites with various compositions are fabricated via the solution cast process. The dielectric permittivity of the composites is significantly increased and the inherent loss is reduced in a wide range of frequencies at the same time. At 100Hz, the 40% PLZST loaded composite shows a dielectric permittivity of 28 (3 times more than that of the neat polymer), and a low loss of 0.045 (near half of that in the neat polymer). The low loss of the composite is most likely due to the slower increasing rate of the conductivity by comparison to the dielectric permittivity.

Susceptible Ferroelectric/Antiferroelectric Phase Transition near the Surface of Nb-Doped Lead Zirconate Stannate Titanate from Surface Processing.

This work systematically investigated the structure and property of the near-surface and bulk regions of Pb0.99(Nb0.02Zr0.73Sn0.21Ti0.04)O3 ceramics using a combination of X-ray and neutron diffraction, piezoresponse force microscopy, and conventional ferroelectric/piezoelectric characterization. It is found that mechanical force can induce an antiferroelectric/ferroelectric phase transition within micrometers of the surface. Such a phase transition is strongly dependent on the processing scenario, leading to differences from the bulk region. This work provides crucial insights into the sensitivity of this class of AFE materials. Clearly, surface processing conditions must be taken into account for both accurate structural determination and practical applications.

Effect of lanthanum modification on dielectric relaxation behavior in lead zirconate stannate titanate antiferroelectric ceramics

The effect of lanthanum concentration on dielectric relaxation behavior in lead zirconate stannate titanate antiferroelectric ceramics was investigated by X-ray diffraction technique, dielectric spectroscopy, Sawyer–Tower polarization methods, and thermally stimulated depolarization current (TSDC) measurements. The tetragonal phase was found to be stabilized from the rhombohedral phase by lanthanum substitution. As the lanthanum content was increased, the dielectric constant decreased gradually over the measuring temperature range. As a result of polarization–electric field hysteresis loops, the maximum polarization decreased and the switching field increased with the increase of lanthanum content. Investigations of TSDC measurements revealed that the peak is due to space-charge polarization. It is suggested to be associated with the relaxation of oxygen vacancies.

Enhancement of Energy Storage Properties in PLZST Cramics with Different Zr/Sn Ratios

The effect of Zr/Sn ratio on the dielectric and energy storage properties of lanthanum modified lead zirconate stannate titanate (PLZST) ceramics with compositions located near the boundary between antiferroelectric and ferroelectric phases was studied. Microstructural observation indicated that all the samples had a uniform morphology with pure perovskite phase and the average grain size reduced obviously with increasing Zr/Sn ratio. As the Zr/Sn ratio increased, the dielectric constant increased and the transition temperature Tm shifted to higher temperature. All the PLZST ceramics exhibited double hysteresis loops. The maximum polarization increased, while the switching field decreased when the Zr/Sn ratio increased. The variations of Zr/Sn ratio had little impact on remanent polarization. As a result, both charged energy density and discharged energy density increased with increasing Zr/Sn ratio. A high energy storage density of 1.75 J/cm3 was achieved in the PLZST ceramics with the Zr/Sn ratio of 82.5/7.5 at 9 kV/mm.

Effect of Nd3+ substitution on electric field induced strain behavior in lead zirconate stannate titanate (68/22/10) ceramics

Abstract Pb 1−3 x /2 Nd x (Zr 0.68 Sn 0.22 Ti 0.1 )O 3 ceramics with large electrical field induced strain were prepared by Nd 3+ doping. X-ray diffraction analysis showed that the substitution of Nd 3+ for Pb 2+ enhanced the stability of antiferroelectric phase due to the decrease of tolerance factor. Besides, with the increase of Nd 3+ addition, the strain first improved with a maximum value at x = 0.02, and then decreased. Further, with increasing electric field and decreasing measuring frequency, the strain improved obviously. This is because that the reversal of the domains is more sufficient at large electric field and long time. The largest strain of 0.63% is obtained in the specimens with x = 0.02 at the frequency 1 Hz.

Phase transition and electric field induced strain properties in Sm modified lead zirconate stannate titanate based antiferroelectric ceramics

The effect of Sm addition on the crystal structures and electrical properties of Pb1−3x/2Smx(Zr0.63Sn0.26Ti0.11)O3 ceramics were investigated in this work. X-ray diffraction analysis showed that with increasing Sm content from 0.005 to 0.03, the phase structure of the specimens underwent transition from ferroelectric (FE) to antiferroelectric (AFE) state due to the substitution of Sm3+ with smaller ion radius for Pb2+ decreasing the tolerance factor of the ceramics. In addition, it was observed that with the improvement of Sm3+ content, the strain of the specimens first increased and then decreased, and the largest value of 0.735% was obtained in the sample with x = 0.015 near AFE/FE phase boundary at the measuring frequency 1 Hz. This is because the reversal of the domains, which produces the strain, is more consummate in this composition. Further, the strain at different frequencies was nearly the same at high electric field, which was attributed to that the electric field applied to the sample was so large that the reorientation of the domains could finish in all measuring frequencies. Both a high strain level and a relatively good frequency stability in the specimen with x = 0.015 make a potential candidate for actuators applications over a wide-frequency working range.

High pyroelectric response of lead zirconate stannate titanate based antiferroelectric ceramics with low Curie temperature

With a view to solve the problem that the Curie temperature of antiferroelectric ceramics was higher than the use temperature of uncooled infrared detectors, four groups of samples with different Ba content were prepared by conventional solid state reaction process, and the effects of Ba2+ content on the ferroelectric, dielectric and electric field-induced pyroelectric properties of four groups of samples were studied. The results indicated four groups of samples showed different dielectric properties which were attributed that the first and the fourth group of samples were in FE phase and the second and the third group of samples were in AFE phase. Large pyroelectric coefficient can be obtained in all four groups of specimens near room temperature by appropriate Ba doping. The maximum pyroelectric coefficient of 13,800μC/m2K and figure of merit of 16.5×10−5Pa−0.5 at room temperature were obtained in (Pb0.97−xBaxLa0.02) (Zr0.7Ti0.05Sn0.25)O3 antiferroelectric ceramics with 0.138mol Ba content.

Dynamic Hysteresis and Scaling Behavior of Energy Density in Pb0.99Nb0.02[(Zr0.60Sn0.40)0.95Ti0.05]O3 Antiferroelectric Bulk Ceramics

The evolution of dynamic hysteresis of lead zirconate titanate stannate antiferroelectric bulk ceramics at various frequencies (f) and field amplitudes (E0) has been investigated systematically. A series of asymmetrical minor loops were observed when the working fields were slightly lower than the forward switching field EAF. As E0 increased above EAF, symmetrical double loops appeared and their energy densities w against f and E0 were found to be fit the scaling behavior as w f−0.02(E0 − Ec)0.08, where Ec representing the threshold field is designated as EAF. The study is helpful to application of antiferroelectrics as energy‐storage capacitors.

The influence of variable quantity of polarization on the current intensity of the electron emission from La-doped Pb(Zr, Sn, Ti)O3 ferroelectric cathode

Ferroelectric cathodes exhibit huge potentials in high-power microwave tube electron beam source, panel display, and the propeller space navigation, due to their superior properties. The material properties of the ferroelectric cathode have been proved to have a significant influence on electron emission, which is indicated in recent research work. In the course of electron emission, the variation of polarization can be caused by non-shielded surface charge which is induced by high trigger voltage. A certain relationship may be found between polarization variation and current intensity of electron emission. To study the relationship between current intensity of electron emission and polarization variation in ferroelectric cathodes, the samples of lanthanum-doped lead zirconate stannate titanate ferroelectric and antiferroelectric ceramics are prepared by the method of solid state calcinations, and the polarization variations of the material under different voltages are measured in the positive half cycle test of hysteresis loop. The curve of the electron emission current intensity versus the trigger voltage is measured, and then the relationship between electron emission current intensity and polarization variation is investigated. The results show that the electron emission current intensities of the two samples are both directly proportional to the polarization variation.

Mechanism of the Pyroelectric Response under Direct-Current Bias in La-Modified Lead Zirconate Titanate Stannate Ceramics

Dielectric and pyroelectric properties of Pb0.97La0.02(Zr0.42Sn0.40Ti0.18)O3 ceramics are investigated as functions of temperature and dc bias field. Induced and intrinsic pyroelectric coefficients pind and p0 are calculated and analyzed. It is found that the sign, value and variation of the net pyroelectric coefficient p with increasing dc bias all are dominated by p0 under applied biases. Polarization and depolarization processes under dc biases are analyzed. Besides the contribution of pind, the diffuse and decreased pyroelectric response under dc bias compared with that of an identical field poled sample without dc bias is mainly attributed to the depolarization process under dc bias.

Effect of Uniaxial Compressive Prestress on the Electromechanical Behavior of Lanthanum Modified Lead Zirconate Titanate Stannate Ceramic

The antiferroelectric ceramics are often subjected to mechanical loading in transducer and high‐strain actuator applications. How the electromechanical behavior changes under different load conditions is therefore very crucial for design. The electromechanical behavior of La‐modified antiferroelectric ceramic lead zirconate titanate stannate (PLZST) under uniaxial compressive prestress is observed at stress up to 100 MPa using a homebuilt experimental setup in conjunction with a modified Sawyer–Tower circuit. The PLZST ceramic researched in this paper is near the ferroelectric—antiferroelectric phase boundary, and it has a lower forward phase transition electric field and slimmer electric hysteresis loop than conventional antiferroelectric ceramics. The results reveal that the area of the double hysteresis (P–E) loops, the saturation polarization (Psat), the longitudinal strain (S), and the remanent polarization (Pr) decrease with increasing compressive prestress, while the forward phase transition field increases as the compressive prestress increases. Meanwhile the applied prestress virtually does not affect the transition field hysteresis (ΔE) and the coercive field (Ec). These results are interpreted through the non‐180° domain switching processes and the stress induced decrease in the switchable part of ferroelectric and antiferroelectric domains under electric field.

Phase transformation and dielectric properties of lead zirconate stannate titanate ferroelectric ceramic under hydraulic compression

Nb-doped lead zirconate stannate titanate ferroelectric ceramic with composition Pb0.99Nb0.02[(Zr0.90Sn0.10)0.96Ti0.04]0.98O3 (PZST 90/10-4-2Nb) is studied in a hydraulic pressure range of 0300 MPa by released charge and dielectric measurements. Pressure-induced low temperature phase transition from ferroelectric rhombohedral (FR(LT)) structure to antiferroelectric orthorhombic (AO) strueture is investigated. Unpoled, poled and pressure-depolarized PZST 90/10-4-2Nb ferroelectric ceramics are used. The released charge quantity is 29.3 C/cm2 and the threshold pressure is 140 MPa during the phase transformation from FR(LT) structure to AO strueture. Dielectric properties show that the threshold pressure of the phase transformation from FR(LT) structure to AO structure is 136 MPa for poled ceramic and 104 MPa for unpoled ceramic. Obvious characteristic of phase transformation is not observed in pressure-depolarized ceramic.

Improvement in shape memory in magnesium niobate modified PZST

A modified lead zirconate stannate titanate system (PZST) has been studied for shape memory effect. Addition of magnesium niobate (MN) slows down the dipole relaxation process, leading to increased (∼3-fold improvement) remnant strain in the PZST system (0.99PZST–0.01PMN). Room temperature X-ray diffraction patterns before poling (antiferroelectric (AFE) tetragonal) and after poling (ferroelectric (FE) rhombohedral), clearly demonstrate that the transition to the ferroelectric phase is stable even in the absence of any electric field. A small applied electric field (∼1.7 kV/cm) in the opposite direction was required to bring the sample back to its original shape. Field-induced strain butterfly loops taken at 50 Hz show that the material response time is quite small.

Pyroelectric energy converter using co-polymer P(VDF-TrFE) and Olsen cycle for waste heat energy harvesting

Abstract This study was concerned with designing, building, and testing a pyroelectric energy converter to directly convert waste heat into electricity. The pyroelectric effect refers to the flow of charges to or from the surface of a material upon heating or cooling. The device consisted of a teflon cylindrical chamber with a piston oscillating vertically and driving a working fluid back and forth between a heat source and a cold heat exchanger. The Olsen cycle was performed on co-polymer 60/40 poly(vinylidene fluoride–trifluoroethylene) [P(VDF-TrFE)] thin films sandwiched between metallic electrodes. Their temperature oscillation, charge, voltage and the overall heat input and output were measured experimentally. Then, the electrical power generated and the energy efficiency were computed. The effects of channel width, frequency, and stroke length on temperature swing, heat input, as well as energy and power densities were investigated. Reducing the channel width and increasing the stroke length had the largest effect on device performance. A maximum energy density of 130 J/l was achieved at 0.061 Hz frequency with temperature oscillating between 69.3 and 87.6 °C. Furthermore, a maximum power density of 10.7 W/l was obtained at 0.12 Hz between 70.5 and 85.3 °C. In both cases, the low and high electric fields in the Olsen cycle were 202 and 739 kV/cm. To the best of our knowledge, this is the largest energy density achieved by any pyroelectric energy converter using P(VDF-TrFE). It also matches performances reported in the literature for more expensive lead zirconate stannate titanate (PZST) ceramic films operated at higher temperatures.

Charge-discharge properties of lead zirconate stannate titanate ceramics

The charge-discharge properties of lanthanum- and niobium-doped lead zirconate stannate titanate ceramics were investigated by directly measuring the hysteresis loops, dielectric constants under a dc bias field, and pulse discharge current-time curves after varying charge-discharge circulations. It was found that there was no significant effect of the charge-discharge circulation on these properties. The first pulse current peak reached 1.8 kA at 40 kV/cm, and most of the stored charge was released in 500 ns. These results show that the obtained slanted ceramics with high energy density can withstand hundreds of charge-discharge circulations and are very promising for pulse capacitor applications.