Lead Zirconate Titanate Piezoceramics Research Articles

Active interface debonding detection of a concrete-filled steel tube with piezoelectric technologies using wavelet packet analysis

Concrete-Filled Steel Tube (CFST) has been widely adopted in high-rise buildings and bridges as a typical structural member carrying vertical loads in recent years. The debonding between the steel tube and the concrete can dramatically reduce the confinement effect of steel tube on the concrete and decrease the load-carrying capacity and the ductility of the CFST. It is still challenging to develop reliable debonding monitoring and detection techniques for CFST because of the inaccessibility of the interface. In this study, an active interface condition monitoring approach for CFST by the use of lead zirconate titanate (PZT) piezoceramics based functional smart aggregates (SAs) embedded in concrete as actuator and PZT patches bonded on the surface of the steel tube as sensors is proposed and verified experimentally. Laboratory tests are performed on the CFST column, in which the deboning is mimicked by setting four thin styrofoam plates with different sizes on different locations of the four internal surfaces of the steel tube, respectively, before casting the concrete. The responses of the PZT sensors are measured when each SA is excited with sweep sinusoidal signals. According to the Fourier spectra and two evaluation indices based on the wavelet packet analysis on the PZT sensors measurements, the artificially mimicked debonding areas are detected successfully. Analysis on the sensitivity of the two evaluation indices shows that the indices based on wavelet packet analysis are more sensitive to the debonding defect. The proposed PZT based active debonding monitoring method provides an innovative approach to detect the debonding damage of CFST columns.

Piezoelectric Behavior Based on Mixing-Doped in Lead Zirconate Titanate Ceramics and Application

In this investigation, we extend our previous works to improve piezoelectric properties of Pb(Zr,Ti)O3 ceramics. Modified lead zirconate titanate (PZT) piezoceramics with a composition Zr/Ti=53/47 containing a trace of mixing dopants were prepared by conventional ceramic technology sintering powder compacts. Replacement of (Zr, Ti)+4 by Nb+5, Pb+2 by Sb+3 and Mn+4 in PZT perovskite type solid solutions was accomplished by the creation of cation and anion vacancies. Modified ceramics were explored as a function of firing temperature to acquire exceedingly good piezoelectric characterizations. From the analysis results, calcined at 850°C for 2 h, and then sintered at 1280°C for 2 h, PZT piezoceramic showed the larger dielectric constant er 2013, mechanical quality factor Qm 120 and maximum electromechanical coupling factor kp 0.67. Besides, the bulk ceramic grains distribution were found to be uniform. Furthermore, the sample was found to possess piezoelectric properties, the resonance frequency being about 200 KHz suitable for acoustic sensor.

Aluminium coating of lead zirconate titanate—A study of cold spray variables

Cold spray was used to deposit conductive aluminium coatings onto lead zirconate titanate (PZT) piezoceramics. The optimisation of processing parameters was explored. Grain removal from the PZT surface due to the impact of Al particles was reduced by increasing the average particle velocity. Surface domain reorientation was detected by X-ray diffraction (XRD). Substrate temperatures during spraying were maintained at a low level by controlling the upstream, cold spray temperature and robot movement. The electrical resistance of the cold sprayed aluminium was 9.9±0.5μΩcm. The impedance characteristics of poled specimens were shown to be unchanged by cold spray.

Raman spectroscopy for the investigation of indentation-induced domain texturing in lead zirconate titanate piezoceramics

The study of the close relationship between crack propagation and domain switching is of extreme importance in the reliability of PbZr1−xTixO3 (PZT) devices. We performed domain imaging in the neighbourhood of indentation cracks on poled and non-poled PZT bulk specimens using polarized micro-Raman spectroscopy. Non-destructive Raman measurements helped to correlate the indentation-induced domain texture with the crack growth resistance on both samples. Hence, polarized micro-Raman spectroscopy offers the potential to locally investigate regions of interest in complex piezoelectric devices.

Effect of MnO2, Bi2O3, and ZnO additions on the electrical properties of lead zirconate titanate piezoceramics

The effect of manganese dioxide additions on the electrical properties of lead zirconate titanate (PZT) piezoceramics has been investigated. The results demonstrate that, taken alone, manganese dioxide does not ensure the formation of hard PZT. The valence state of manganese in the piezoceramics is shown to be 4+ if no other dopants are present and 3+ if manganese is introduced in combination with Bi and Zn. Microstructural examination indicates that the grain size of the singly doped ceramics is 5–15 µm, while that of the codoped ceramics is 1–3 µm. The polarization current curves of the piezoceramics containing manganese, bismuth, and zinc oxides have extra maxima, which points to significant internal fields. The manganese is shown to reside at grain boundaries. The conclusion is made that it is the composition of Mn-containing intergranular phases, rather than the presence of manganese ions, that plays a key role in the formation of hard piezoceramics.

Determination of room-temperature creep of soft lead zirconate titanate piezoceramics under static electric fields

This study focuses on the experimental investigation of the time-dependent effects of a commercial soft lead zirconate titanate material at room temperature. Samples in initially unpoled states were subjected to a cyclic stepwise electric field which was kept constant at different levels for 300 s. Due to ferroelectric domain switching, significant nonlinearity and hysteresis were observed in the overall polarization and strain response. In particular, the material exhibited creep behavior as the applied electric field was held constant over extended periods of time. This creep was caused by microscopic domain switching processes induced gradually during the holding time. The creep was of primary or transient type in nature and depended strongly on the magnitude of the load applied. Most pronounced creep was observed when holding the field close to the coercive field. Logarithmic representation of the polarization or strain versus time curves indicated that the creep behavior could be quantified approximately by the Andrade power law. The creep exponents were determined for different field conditions. The results may help the understanding of the creep mechanism, which in turn provides contributions to improve the performance and reliability of ultrahigh-precision positioning piezoactuators.

Modeling, Optimization, and Design of Efficient Initially Curved Piezoceramic Unimorphs for Energy Harvesting Applications

The piezoceramic, lead zirconate titanate (PZT), is capable of producing large voltages with relatively minimal currents in response to an applied mechanical load when employed in initially curved laminates. This study addresses the issue of optimizing design parameters of a curved PZT unimorph to maximize charge generation due to mechanical loading. A horizontally placed PZT unimorph structure generates surface charge when vertically loaded and the charge can be collected using charge-collecting circuitry. In order to identify and optimize the variables fundamental to the design process, an analytical model of the curved PZT unimorph was developed using shallow thin shell theory and linear piezoelectric constitutive equations. An expression for charge generation was then derived in terms of geometrical dimensions, material properties and applied loading. The model was experimentally verified with samples consisting of different geometries and loadings. Finally, the analytical model was used to generate optimal design characteristics or ‘rules of thumb’ necessary for optimum design. It is envisioned that these ‘rules of thumb’ will be used by practitioners to design efficient charge generating devices.

Experimental investigation of domain switching criterion for soft lead zirconate titanate piezoceramics under coaxial proportional electromechanical loading

In this experimental work, “soft” lead zirconate titanate specimens in an initially unpoled state were subjected to combined electromechanical loading, in which a compressive stress and a parallel, proportional electric field were applied simultaneously. By changing the ratio of stress to the electric field between tests, a series of nonlinear polarization and strain responses were obtained. An attempt has been made to explain the experimental findings by simultaneously taking into account the contributions of dielectric response, elastic deformation, piezoeffects, and irreversible domain switching. Initial domain switching surfaces in the biaxial stress and electric field space were determined based on an offset method. Several switching conditions existing in the literature were summarized and compared with the experimental data obtained in this work. Such an investigation may serve to calibrate and validate existing constitutive models concerning the large-signal nonlinear behavior of piezoceramics.

Effects of Bias Electric Fields on the Non‐linear Ferroelastic Behavior of Soft Lead Zirconate Titanate Piezoceramics

Modern piezoelectric transducers normally have complicated structures and work under severe loading conditions. Due to their inherent domain‐switching processes, the real response of piezoceramics under large‐signal loading is dominated by a significantly non‐linear behavior that is to be considered in reliability assessment and devices design. This paper presents systematic measurements of the non‐linear depolarization and strain behavior of soft lead zirconate titanate piezoceramics over a wide range of compression loads and bias electric fields. An attempt has been made to explain the experimental findings by simultaneously taking into account the contributions of dielectric response, elastic deformation, irreversible domain switching, and piezoeffects.

Preparation of hard lead-zirconate-titanate-based piezoceramics

Fluorinated lead zirconate titanate piezoceramics are prepared using mechanical activation of the starting mixture and synthesized ceramic powder in a vibratory mill, and their physical properties are studied. The introduction of fluorine (1–5 mol %) into the starting mixture enhances the dielectric rigidity of the material. The addition of 0.1–0.3 mol % F in combination with 0.3–3 mol % Fe makes it possible to produce hard piezoceramics capable of operating in electric fields of up to 3 kV/cm. The ceramics have a tetragonally distorted perovskite structure and consist of grains 1–2 em in size. X-ray microanalysis of specimens prepared by polishing and etching reveals significant compositional inhomogeneities.

High-field dielectric and piezoelectric performance of soft lead zirconate titanate piezoceramics under combined electromechanical loading

Piezoelectric actuators normally have complicated structures and work under severe loading conditions, e.g., high driving electric field and significant compressive preload. This study is focused on the experimental investigation of the electromechanical properties of a commercial soft lead zirconate titanate material under loading conditions simulating the in-service environment of high-strain actuators. The polarization and strain responses were first measured under a constant-stress preload. A significant enhancement of the dielectric and piezoelectric performance is observed within a small prestress range. At much higher preload levels, the predominant mechanical depolarization effect makes the material exhibits hardly any piezoeffect. In the other two series of tests, the specimen was subjected to cyclic mechanical load with different mean stresses and amplitudes. When the stress is applied in-phase with electrical loading, the polarization and strain outputs are found to monotonically decrease with an increase in stress amplitude, until mechanical loading completely impedes the piezoelectric response. An inverse effect occurs for the out-of-phase electromechanical loading tests, in which the polarization and strain outputs increase with increasing stress amplitude. In general, the enhanced polarization and strain responses are accompanied by an unfavorable increased hysteresis and, consequently, increased energy loss. An attempt has been made to explain the experimental findings by simultaneously taking into account the effects of dielectric response, elastic deformation, irreversible domain switching, and piezoeffects.

Open-loop flutter analysis of a composite UAV model using the active stiffening effect

This study investigates the influence of the active stiffening effect of a smart piezolaminated composite Uninhibited Aerial Vehicle (UAV) model on the flutter mechanisms, using the MSC/NASTRAN finite element code. The composite UAV contains piezoceramic lead–zirconate–titanate (PZT) continuous layers bonded to the whole top and bottom surfaces of its wings. Applying in-phase DC voltage to the actuators performs the active stiffening. The actuators are evaluated by means of the pin-force model using the linear piezoelectric constitutive relations. The constructed aeroelastic model is transformed into time-domain (state-space) form. The idea is to use piezoelectric actuators as active stiffeners to the UAV's dynamical properties, by means of increasing natural frequencies and therefore altering its flutter velocities.

Promotion of piezoelectric properties of lead zirconate titanate ceramics with (Zr,Ti) partially replaced by Nb2O5

This study investigated the correlation of sintering effects on piezoelectric properties of Nb modified lead zirconate titanate (PZT) piezoceramics produced by the conventional solid reaction sintering. Samples were prepared at a composition Zr/Ti=53/47, contiguous to a morphotropic phase boundary (MPB) for 1 mol% Nb2O5. Replacement of Ti+4 by Nb+5 in such perovskite type solid solutions was accomplished by the creation of cation vacancies. These created vacancies seemed to facilitate material transport and benefit sintering. Calcined at 850 °C/2 h and sintered at 1250 °C/2 h, the PZT ceramics yielded a minimum value of the mechanical quality factor (Qm) 50, and exhibited a maximum electromechanical coupling factor κp 0.62, in accordance with the relationship between the mechanical quality factor and electromechanical coupling factor. In addition, during the sintering process a piezoelectric charge constant at d33 was found to be of 385 pC/N. It was noted that the fundamental resonance frequency was around 200 kHz, which was suitable for piezoelectric nebulizer (fluid atomizer), ultrasonic cleaning transducer applications.

Uniaxial Compressive Stress Dependence of the High-Field Dielectric and Piezoelectric Performance of Soft PZT Piezoceramics

The influence of uniaxial prestress on dielectric and piezoelectric performance was studied for soft lead zirconate titanate piezoceramics. High electric field induced polarization and longitudinal/transverse strain were measured at different compression preload levels of up to −400 MPa. The parameters evaluated included polarization/strain outputs, dielectric permittivity, piezoelectric constants, and dissipation energy as a function of the mechanical preload and electric-field strength. The results indicate a significant enhancement of the dielectric and piezoelectric performance within a certain prestress loading range. At much higher stress levels, the predominant mechanical depolarization effect makes the material exhibit hardly any piezoeffect. However, the enhanced performance achieved by a small stress preload is accompanied by an unfavorable increased hysteresis, and consequently, increased energy loss, which is attributed to a larger extrinsic contribution due to more non-180° domain switching induced by the combined electromechanical load.

Variability of impurity doping in the modified Pb(Zr,Ti)O3 ceramics of type ABO3

The influence of sintering effects on microstructure, mechanical quality factor Qm and electromechanical coupling factor κ of 1mol% Nb-doped lead zirconate titanate (PZT) piezoceramics with a composition Zr/Ti=53/47 prepared by the conventional ceramic technology were investigated. Replacement of Ti+4 by Nb+5 in such perovskite type solid solutions was accomplished by the creation of cation vacancies. These created vacancies seemed to facilitate material transport and benefit from sintering. Calcined at 850 °C/2 h and sintered at 1250 °C/2 h, the PZT ceramics had the minimum value of Qm 50 and exhibited maximum electromechanical coupling factor κp 0.62 in accordance with the relationship between mechanical quality factor and electromechanical coupling factor. The measured P–E hysteresis loop illustrated that the remanent polarization (Pr) and coercive field (Ec) were 8.63 μC/cm2 and 17.2 kV/cm, respectively. The fundamental resonance frequency was around 200 kHz, which was suitable for piezoelectric resonator and filter applications.

Determination of full set material constants of piezoceramics from phase velocities

The determination of elastic and piezoelectric constants by means of the resonance method is described in detail in the Institute of Electrical and Electronics Engineers Standards. However, in practice, it is not easy to obtain a self-consistent complete set of elastic and piezoelectric coefficients using the resonance method alone, since the geometric requirements are often too difficult to meet in some materials and property variation from sample to sample could be substantial. In this article, we report on a characterization scheme by regression of ultrasonic velocities in different directions. The method using the Levenberg-Marquardt algorithm is very stable. Only two samples are needed to determine the whole set of the material constants. The method has been applied to doped piezoceramic lead zirconate titanate and material constants obtained at the same frequency show excellent self-consistency.

Improved ultrasonic spectroscopy methods for characterization of dispersive materials.

Transmission ultrasonic spectroscopy method has been successfully implemented for the characterization of piezoceramics at high frequencies. There are, however, still some intrinsic error sources that limit the accuracy of the method. In this paper, two improved ultrasonic spectroscopy methods are presented, which can reduce the number of pre-required parameters and reduce another error source. The two improved methods were used to measure the frequency dispersion of phase velocity and attenuation of doped piezoceramic lead zirconate titanate (PZT-5A); results were compared with those obtained from the conventional method. The advantages and limitations of each method are discussed.

Effects of uniaxial stress on the piezoelectric, dielectric, and mechanical properties of lead zirconate titanate piezoceramics

Piezoelectric ceramics are often used under compressive stress. It is therefore important to know the properties of these materials as a function of applied stress. We have developed an experiment that allows us to find the piezoelectric charge coefficient d33, elastic compliance SE 33, and dielectric constant ϵT 33 as a function of uniaxial stress in the poled direction. Both dynamic and static measurements can be carried out. The dynamic and static coefficients differ from each other because of the different proportions of reversible and irreversible domain changes that contribute to them and each coefficient can be important in specific applications. Dynamic results for stresses up to 160 MPa on a soft and a hard piezoelectric Lead Zirconate Titanate (PZT) ceramics are presented. The time dependence of the measurement has also been investigated. It was found that the experimental results were strongly dependent on the material type, history of the specimen, stress level, and the time scale of the measurement.

Nonlinear properties of lead zirconate–titanate piezoceramics

Nonlinear properties of lead zirconate-titanate (PZT) piezoceramics are investigated using ultrasonic second harmonic generation technique. When a sinusoidal ultrasonic wave of frequency ω0 is sent into a nonlinear material, the second harmonic wave with frequency 2ω0 is generated. Through measuring the absolute amplitude of the fundamental (ω0) and of the second harmonic (2ω0) waves, the ultrasonic nonlinearity parameter β can be determined, which involves certain combinations of the third-order elastic constants and piezoelectric coefficients. We report the measured nonlinear parameters for four types of doped PZT ceramics, PZT-4, PZT-5A, PZT-5H, and PZT-5H HD, which are widely used in practice. We found that the nonlinear parameter is much more sensitive than the linear parameter in responding to microstructural changes in piezoceramics. It could be used to distinguish unpoled samples from depoled samples, which are undistinguishable in terms of the linear parameters.

Electromechanical properties of lead zirconate titanate piezoceramics under the influence of mechanical stresses

In lead zirconate titanate piezoceramics, external stresses can cause substantial changes in the piezoelectric coefficients, dielectric constant, and elastic compliance due to nonlinear effects and stress depoling effects. In both soft and hard PZT piezoceramics, the aging can produce a memory effect that will facilitate the recovery of the poled state in the ceramics from momentary electric or stress depoling. In hard PZT ceramics, the local defect fields built up during the aging process can stabilize the ceramic against external stress depoling that results in a marked increase in the piezoelectric coefficient and electromechanical coupling factor in the ceramic under the stress. Although soft PZT ceramics can be easily stress depoled (losing piezoelectricity), a DC bias electric field, parallel to the original poling direction, can be employed to maintain the ceramic poling state so that the ceramic can be used at high stresses without depoling.