Lead Zirconate Titanate Ferroelectric Ceramics Research Articles

Inhomogeneous electric field-induced structural changes in soft lead zirconate titanate ferroelectric ceramics

Under the application of an external voltage, high electric field concentrations can develop around the interdigitated electrode edges inside multilayer ceramic actuators (MLCAs). The spatial distribution of the local electrical field can create local inhomogeneity in the electromechanical response. To investigate the complex field inhomogeneity in MLCAs, partially electroded Nb-doped PbZrxTi1-xO3 samples were investigated via synchrotron-based high-energy X-ray diffraction (XRD) as a function of applied electric field. These in situ experiments allowed us to probe the structural changes as a function of position relative to the electrode edge and calculate the local degree of domain alignment, from which the local electric field directions were inferred. The domain switching behavior, both in amplitude and orientation, was found to be spatially dependent across the inactive regions in partially electroded samples. Specifically, the degree of domain alignment and field-induced phase transitions are amplified near the electrode edge. The orientation-dependent phase transitions are also amplified for the tetragonal composition near the morphotropic phase boundary (MPB), i.e., the Nb-doped PbZr0.53Ti0.47O3 composition. Finite element analysis (FEA) shows spatially-dependent, inhomogeneous electric field distributions in the partial-electrode samples, which closely match the experimentally inferred local electric field directions from XRD. The correlation of FEA and experimental data from XRD corroborates that the ferroelectric domain orientation distributions are being directed, primarily, in the direction of the electric field.

Inhomogeneous Electric Field-Induced Structural Changes in Soft Lead Zirconate Titanate Ferroelectric Ceramics

Inhomogeneous Electric Field-Induced Structural Changes in Soft Lead Zirconate Titanate Ferroelectric Ceramics

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.

Low-temperature sintering of (Pb1−xCdx)(Zr0.965Ti0.035)O3 ferroelectric ceramics for multilayer device application

ABSTRACTLow-temperature sintering behaviour and ferroelectric properties of lead zirconate titanate (PZT95/5) ferroelectric (FE) ceramics doped with CdO were investigated. The addition of CdO significantly promoted the densification and decreased the sintering temperature of PZT95/5 ceramic. When the addition of CdO content is 1 mol-%, PCZT95/5 ceramics with a relative high density of approximately 97.5% can be obtained by sintering at 1100°C and exhibits excellent electric properties with d33 values of 65 pC/N, this d33 value is close to that of PZT95/5 ceramic sintered at 1350°C. With an increase in the CdO content, the FE phase content decreases and the antiferroelectric (AFE) phase content increases gradually. When the CdO content is 2 mol-%, the most of FE phase of PCZT 95/5 ceramics changes to AFE phase, the polarisation value is quite small and the d33 value drops to zero.

Mechanical properties and phase transformation of porous unpoled Pb(Zr0.95Ti0.05)O3 ferroelectric ceramics under uniaxial compression

Four kinds of unpoled lead zirconate titanate (PZT95/5) ferroelectric ceramics were fabricated in a range of different porosity levels by systematic additions of added pore formers. By using the non-contact digital image correlation (DIC) optical technique to measure the full-field strain, the response of unpoled PZT95/5 ferroelectric ceramics to statically applied uniaxial stresses was investigated. The influences of porosities on the mechanical behavior, domain switching, and phase transformation of the porous unpoled PZT95/5 ferroelectric ceramics were explored. All the measured stress versus strain curves for the tested porous unpoled PZT95/5 ferroelectric ceramic samples can be divided into three stages: the initial linear elastic region, the approximate plateau region, and the second linear elastic region, similar to the behavior of foam or honeycomb materials. However, the deformation mechanism of porous unpoled PZT95/5 ferroelectric ceramics should be attributed to the domain switching and phase transformation processes, but not related to the collapse of voids. With the increase of porosity, the elastic modulus, fracture strength and fracture strain of the porous unpoled PZT95/5 ferroelectric ceramics would decrease. Effect of dispersed voids does not improve plasticity of the porous unpoled PZT95/5 ferroelectric ceramics, which is mainly attributed to no effect of the pores on the obstacle and proliferation of crack propagation during the axial splitting failure processes. Critical stresses of the domain switching and phase transformation decrease linearly with increasing porosity. The macroscopic critical volumetric strain needed for phase transformation is independent of the porosity in the unpoled PZT95/5 ferroelectric ceramics.

Depolarization and Electrical Response of Porous PZT 95/5 Ferroelectric Ceramics under Shock Wave Compression

The release of bound charges by shock wave loading of poled lead zirconate titanate (PZT 95/5) ferroelectric ceramics can result in a high-power electrical energy output. In this study, a theoretical formulation describing the depolarization and electrical response of porous PZT 95/5 ceramics in the normal mode to shock wave compression loading perpendicular to the polarization direction is developed. The depoling process in porous poled PZT 95/5 ceramics is analyzed by using a parallel circuit consisting of a current source, capacitance, conductance and a circuit load. This modeling takes the effects of porosity on wave velocity and remanent polarization and dielectric constant into account, and the effects of variations in dielectric constant and conductivity in the shocked region are assessed. The output current characteristics of porous PZT 95/5 ceramics under short-circuit and resistive load conditions are analyzed and compared with the experiment, with the results showing that theoretical predictions taking into consideration the porosity of ferroelectric ceramics are in close agreement with the experimentally measured electrical response of porous PZT 95/5 under shock wave compression loading.

Pyroelectric behavior and thermally stimulated processes in niobium modified lead zirconate titanate ferroelectric ceramics

The thermally stimulated processes in niobium modified lead zirconate titanate ferroelectric system are analyzed from the thermally stimulated depolarization current. Different theoretical models are considered to evaluate the i-T experimental data. The results are associated with the space charge, the pyroelectric response, and the electrical conduction mechanism related to the oxygen vacancies. The results for the pyroelectric contribution are discussed considering the niobium concentration.

Influence of the A and B vacancies on the dielectric and structural properties of the PLZT 8/60/40 ferroelectric ceramic system

The lanthanum modified lead zirconate titanate (PLZT) ferroelectric ceramics, considering La/Zr/Ti ratio of 8/60/40 and vacancies in A or B sites of the perovskite structure, have been analyzed by using X-ray diffraction, dielectric response, polarized light microscopy and ferroelectric hysteresis. No remarkable differences are observed between samples with A or B vacancies from the X-ray diffraction patterns and ferroelectric hysteresis loops. However, the dielectric measurements have revealed a significant decrease in the maximum values for the real part of the dielectric permittivity and an enhancement of the relaxor behavior in the systems where A vacancies have been considered. On the other hand, the anomalies observed in the temperature dependence of the remanent polarization suggest a frozen out in the dynamic of Nanometric Polar Regions (PNRs) around the same region of temperatures for both samples.

Investigation and characterization of Pb(Zr 0.52Ti 0.48)O 3 nanocrystalline ferroelectric ceramics: By conventional and microwave sintering methods

The lead zirconate titanate (PZT) ferroelectric ceramics was sintered using microwave sintering and conventional sintering technique, respectively. The formation of single phase was confirmed by X-ray diffraction. It has been observed that the microwave sintered PZT ceramics show better densification, fine and uniform grain size, higher dielectric constant and improved piezoelectric coefficient constant d 33. The dielectric properties were studied as a function of frequency and temperature. This promising technique has distinguished characteristics of energy-saving, rapid processing and uniform temperature distribution throughout the sample. The values of remnant polarization, P r, and spontaneous polarization, P s, are slightly higher for microwave sintered sample. The value of E c in the microwave sintered sample is low and this property was desirable for device fabrication of PZT-based smart structures.

Effect of Humidity on Delayed Propagation of Indentation Crack under Sustained Electric Field in Ferroelectric Ceramics

The effect of humidity on delayed propagation of indentation crack in lead zirconate titanate ferroelectric ceramics under sustained electric field was investigated. The results indicated that delayed propagation of indentation crack could occur in humid air at 98%RH without electric field but it did not in air at RH  30%. The threshold electric field and incubation time for delayed propagation of indentation crack increased but the increment of propagation length decreased with decreasing the humidity. When the electric field is large of 0.14 times of the coercive field, the delayed propagation could also occur in vacuum.

Influence of Temperature on Dielectric and Piezoelectric Behaviors of Stannate Modified Lead Zirconate Titanate Ceramics

Phase transformation induced by temperature of stannate-modified lead zirconate titanate ferroelectric ceramics was investigated. The chosen composition is Pb0.99Nb0.02[(Zr0.90Sn0.10)0.95Ti0.05]0.98O3 which was abbreviated as PZST85/10/5–2Nb. The low temperature rhombohedral ferroelectric (FR(LT))-high temperature rhombohedral ferroelectric (FR(HT))-paraelectric phase (PE) sequence induced by temperature was observed in poled PZST85/10/5–2Nb ceramic by measuring the dielectric response, hysteresis loop and piezoelectric coefficient d33. There was a relatively slight change of loss factor, hysteresis loop (remanent polarization, coercive field and area of loop) and piezoelectric constant d33 during FR(LT)-FR(HT) phase transformation. Sharp maxima of dielectric constant and piezoelectric constant d33 occur in FR(HT)-PE phase transformation.

Phase transition study of integrated circuit chip power supplying based on ferroelectric ceramic

We introduce the tin-modified and niobium-modified lead zirconate titanate ferroelectric ceramics as a micropower supplying source for integrated circuit chip. The ferroelectric ceramic phase transition under transverse shock wave compression can release the depolarization energy to the external storage capacitor. The porous microstructure ferroelectric ceramic micropower-generator is capable of generating low output voltage pulses with amplitudes 50.3 V and with transferred energy 1.12 mJ, and supplying integrated circuit chip with micropower sources. Theoretical calculations are conducted based on circuit analysis law, principle of dynamic high pressure, and shock wave physics, and the calculated response matches well with experimental data.

Depth Dependence of Fatigue in Bulk Lead Zirconate Titanate Ceramics Studied by Piezoresponse Force Microscopy

Depth dependence of fatigue in bulk lead zirconate titanate ceramics (PZT) has been investigated by means of piezoresponse force microscopy. The local domain switching in PZT ceramics at microscopic level was examined. It has been shown that the fatigue state underneath the electrodes is more developed than in the interior of the wedge-cut samples of fatigued ferroelectric lead zirconate titanate ceramics. The predominance of fatigue effect occurrence underneath the electrodes is attributed to the domain pinning by defect agglomerates.

Refatigue of Ferroelectric Lead Zirconate Titanate

Bipolar fatigue of ferroelectric lead zirconate titanate ceramics can be partly recovered by thermal annealing. For samples of initially, intermediately, or highly fatigued state, subsequent refatiguing yields a much more rapid decay in polarization and piezoelectric constant than the initially nonfatigued samples despite very similar recovery from annealing. The “material memory” of the prior fatigue treatment is discussed in the framework of microcracking and fixed polarization by crack face charges.

Effect of external fields on the switching current in PZT ferroelectric ceramics

The dependence of a switching current in lead zirconate titanate (PZT) ferroelectric ceramics on the temperature and an applied electrical field was investigated. It was found that temperature has a moderate contribution to the switching current values, but applied electric fields have significant effects on the values. Importantly, a relaxation of switching current on frequency was observed through this method. By a comparison investigation on PZT ceramics of different compositions non- 18 0 ∘ domain switching was found to be responsible for the relaxation. A function, the ‘active potential of domains’ was proposed to interpret the observed results from the viewpoint of energy. The results obtained provide a new understanding of domain process in ferroelectric ceramics that relaxation of domains is a collective motion of non- 18 0 ∘ domains.

Highly Ordered, Millimeter‐Scale, Continuous, Single‐Crystalline Graphene Monolayer Formed on Ru (0001)

The ferroelastic phase transition and shape memory effect in La-modified lead zirconate titanate ferroelectric ceramics are demonstrated directly through the temperature-dependent macroscopic recoverable strain measured in a three-point bending configuration. X-ray diffraction measurements reveal that non-180 degrees domain switching occurs in the mechanically poled sample in two different ways at the bottom and top of the sample which have been under tensile and compressive stresses, respectively. The calculated fraction of non-180 degrees switched domains in the poled sample increases nonlinearly with the applied force and shows a saturation trend, which is consistent with the nonlinear behavior of the remnant strain. This study confirms that the mechanical stress applied upon cooling ferroelectric ceramics from the paraelectric to the ferroelectric phase can easily activate ferroelastic domain switching and give rise to preferred domain orientation and consequent macroscopic remnant strain which results in a history effect and shape memory effect via the ferroelastic phase transition.

The ferroelastic phase transition and non-180° domain switching in La-modified lead zirconate titanate ferroelectric ceramics

The ferroelastic phase transition and shape memory effect in La-modified leadzirconate titanate ferroelectric ceramics are demonstrated directly throughthe temperature-dependent macroscopic recoverable strain measured in athree-point bending configuration. X-ray diffraction measurements reveal that non-180° domain switching occurs in the mechanically poled sample in two differentways at the bottom and top of the sample which have been under tensileand compressive stresses, respectively. The calculated fraction of non-180° switched domains in the poled sample increases nonlinearly with the applied force andshows a saturation trend, which is consistent with the nonlinear behavior of the remnantstrain. This study confirms that the mechanical stress applied upon cooling ferroelectricceramics from the paraelectric to the ferroelectric phase can easily activate ferroelasticdomain switching and give rise to preferred domain orientation and consequent macroscopicremnant strain which results in a history effect and shape memory effect via the ferroelasticphase transition.

Effect of humidity on subcritical crack growth of indentation crack under sustained electric field in PZT ceramics

The effect of humidity on subcritical crack growth of indentation crack in lead zirconate titanate (PZT) ferroelectric ceramics under various sustained electric field has been investigated. The results showed that subcritical crack growth of indentation crack could occur in humid air of 60%RH without electric field but did not in air with RH ≤ 30%. The subcritical crack growth could occur in vacuum under a sustained electric field of E/ E C = 0.14. The incubation time decreased and the amount of the subcritical crack growth increased with increasing the humidity under the sustained field. The threshold electric field for subcritical crack growth decreased with increasing the humidity.

Grain growth kinetics and electrical properties of lanthanum modified lead zirconate titanate (9/65/35) based ferroelectric ceramics

The influence of the microstructural characteristics on the dielectric and electrical properties has been investigated for Nd3+ doped lanthanum modified lead zirconate titanate ferroelectric ceramics, obtained by the conventional solid-state reaction method, by taking into account different sintering conditions. The grain growth mechanism has been investigated and a cubic-type grain growth law was observed for samples with grain size varying from 1.00 up to 2.35 μm. The porosity and grain size dependences of the phase transition parameters, such as the maximum dielectric permittivity and its corresponding temperature (εm and Tm, respectively) were also investigated. The ac conductivity analyses followed the universal Jonscher law. The behavior of the frequency exponent (s) was analyzed through the correlated barrier hopping model. Both ac and dc conductivity results have been correlated with the observed microstructural features.

Modeling the dielectric response of lanthanum modified lead zirconate titanate ferroelectricceramics—an approach to the phase transitions in relaxor ferroelectrics

The relaxor behavior of lanthanum modified lead zirconate titanate (PLZT) ferroelectric ceramics, for aLa/Zr/Ti ratioof x/60/40, has been analyzed. An approximation to the dynamical behavior of the polar nano-regions(PNRs) has been discussed, taking into account a relaxation model, which considers adistribution function for the relaxation times. A good agreement between theoretical andexperimental results was obtained. The behaviors of the mean relaxation time and itsstandard deviation with temperature were discussed, considering the correlation betweenthe polar nano-regions and the freezing temperature. The temperature dependence of thepolarization showed an anomalous behavior around a temperature, which was associatedwith the freezing temperature, according to the proposed model in the present work.