Damping characteristics of chlorobutyl rubber/poly(ethyl acrylate)/piezoelectric ceramic/carbon black composites

In this study, a new kind of damping composite consisting of chlorobutyl rubber, poly(ethyl acrylate), piezoelectric ceramic (PZT), and carbon black (CB) was prepared, and some efforts were made to characterize the damping behavior and explore the damping mechanism. The damping behaviors of the composites were mainly decided by the contents of CB and PZT. When an external vibration was exerted on the composites, the mechanical energy of vibration was transformed into electric energy by PZT; if the resistance was adjusted to a suitable range by the variation of the CB content, the composites could behave as semiconductors: the electric energy could not be transferred to the surface of the material but rather was dissipated as thermal energy. For this system, when the contents of CB and PZT were between 10 and 30 vol %, respectively, the volume resistivity was between 10⁵ and 10^9.5 Ω cm, and a good damping performance could be achieved. On the basis of the results, a theoretical model is proposed to explain the damping performance of the composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Micromoulding of PZT film structures using electrohydrodynamic atomization mould filling

In this work, electrohydrodynamic atomization combined with a photolithography polymeric micromoulding technique was used to form PZT ceramic structures. PZT thick film structures consisting of squares and rectangles of various sizes and separations were produced and used to evaluate the process. An expansion effect of approximately 10 μm on the ceramic structure width relative to the 200 μm wide mould design was observed. The minimum continuous gap between features achieved using this process was 13.5 μm, and the smallest regular PZT square structure obtainable was 106 μm in width. A sloping side wall of the PZT structures caused by the shielding of the photoresist mould was also observed in the process. The resulting PZT structures had a homogenous microstructure and exhibited a relative permittivity of 250, d_33, f of 67 pCN^?1 and remnant polarisation of 8.8 μC/cm².     

Effects of microwave heating on dielectric and piezoelectric properties of PZT ceramic tapes

Commercial lead zirconate titanate (PZT) perovskite powders were used to fabricate ceramic tape and then sintered by microwave and conventional methods. Both dielectric and piezoelectric properties of PZT ceramic tapes were studied in terms of sintering process. X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) show the PZT perovskite phase with smaller grain size and dense microstructure can be obtained at a lower sintering temperature by microwave process. It was also observed that shrinkage ratio and bulk density of the tapes sintered at 800 °C were obtained about 19% and 7.46 g/cm³ by the microwave heating method, respectively, that is corresponding to those values of sintered PZT tapes at 950 °C by conventional process. Moreover, the dielectric constant and maximum permittivity are increased about 30% as compared with conventional processing method. The experimental results demonstrated that the characteristics of the PZT tapes could be significantly improved by microwave heating method. These results demonstrate that such a simple approach can upswing the piezoelectric and dielectric properties of these tapes by using microwave process with a short heating time.     

Microstructure Development of PZT Ceramics by Doping with Small Amounts of Al2O3, SiO2, and Fe2O3

Lead zirconate titanate (PZT) ceramics are used in a wide range of applications as sensors and actuators. Typically, they are formulated by the mixed oxide route, using several mixing and milling steps. Due to wear, these processes introduce impurities into the ceramic mass, which on their part can strongly influence densification behaviour and final properties of the PZT. In this study, the effect of such impurities, such as iron oxide, alumina, and silica, on the sintering behaviour and microstructure development of PZT ceramic is evaluated. A commercial Nb‐doped PZT powder was used and doped by adding Al₂O₃, SiO₂, and Fe₂O₃ with an amount of up to 0.001 mol%. Bulk samples were prepared and sintered in air. The mass loss, density, and grain size were correlated by regression analysis using the doping elements and levels, respectively. Due to the complex interactions between the oxides and the ceramic properties, the experiments were performed with the design‐of‐experiment method (DoE). The results showed a significant influence of these low amounts of doping levels on the microstructure development. Moreover, it was shown that doping after calcination affects the microstructure in a similar way to doping before calcination. Thus, a possibility to compensate concentration variations in the calcined ceramic mass is demonstrated, to homogenize the chemical composition and the final microstructure of the sintered PZT ceramic in the manufacturing processes.     

Effect of heat treatment on the electrical properties of lead zirconate titanate/poly (vinylidene fluoride) composites

Ceramic/polymer composites are attracting increasing interest in materials research and practical applications due to the combination of excellent electric properties of piezoelectric ceramics and good flexibility of polymer matrices. In this case, the crystallization of the polymer has a significant effect on the electric properties of ceramic/polymer composites. Based on different heat treatment methods, the crystallization of poly(vinylidene fluoride) (PVDF) in composites of lead zirconate titanate (PZT) and PVDF can be controlled effectively. PZT/PVDF composites with various PVDF crystallizations exhibit distinctive dielectric and piezoelectric properties. When the crystallization of PVDF is 21%, the PZT/PVDF composites show a high dielectric constant (ε) of 165 and a low dielectric loss (tan δ) of 0.03 at 10³ Hz, and when the crystallization of PVDF reaches 34%, the piezoelectric coefficient (d₃₃) of PZT/PVDF composites can be up to ca 100 pC N^?1. By controlling the crystallization of PVDF, PZT/PVDF composites with excellent dielectric and piezoelectric properties were obtained, which can be employed as promising candidates in high‐efficiency capacitors and as novel piezoelectric materials. Copyright © 2010 Society of Chemical Industry     

Formation of PZT micro-scale structures using electrohydrodynamic atomization filling of metallic moulds

In our previous work electrohydrodynamic atomization (EHDA) combined with a photolithography polymeric micromoulding technique was used to form PZT ceramic micro-scale structures. The major drawback of this technique was the deformation of the polymeric mould resulting in irregular PZT structures.In order to overcome the above drawback, nickel micromoulds were used in this work to form PZT structures. It was observed that the PZT structures presented more regular features compared with those obtained from polymeric micromoulds. The smallest PZT square sizes and separations achieved were 78 μm and 31 μm, which correspond to the minimum nickel micromould cavity obtainable. The side wall angle was increased by using a release agent to prevent excessive build up of PZT at the edges of the mould cavity. The resulting PZT structures exhibited a relative permittivity of 240, d_33,f of 70 pCN^?1 and remnant polarisation of 9.3 μC cm^?2 at 35 V μm^?1.     

Co-sintered PZT ceramics for the piezoelectric transformers

The co-sintered functionally graded PZT ceramic transformers working in a k_p-mode in both input and output circuits were studied. Theoretical model was developed to describe the transformation ratio as a function of the frequency. Transformation ratio, efficiency and power density are measured for the set of samples with homogenous PZT and variable input/output PZT compositions for the low-power signal and compared with the derived formulae. The maximum efficiency is observed for the homogenous hard PZT compositions (type APC840). Contrary to the theoretical calculations, co-sintering hard PZT ceramics along with the soft PZT were not experimentally proven to produce a noticeable increase in the transformation ratio, efficiency and output power density probably due to the difference in optimal sintering temperature.     

Higher permittivity of Ni-doped lead zirconate titanate,Pb[(Zr0.52Ti0.48)(1-x) Nix]O3, ceramics

The paper reports highest obtained dielectric constant for Ni-doped Lead Zirconate Titanate [PZT, Pb(Zr_0.52Ti_0.48)O₃] ceramics. The Ni-doped PZT ceramic pellets were prepared via conventional solid-state reaction method with Ni content chosen in the range 0–20?at%. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were employed to investigate the crystal structure of the prepared ceramics. The X-ray diffraction analysis indicated that the ceramic pellets had crystallized into tetragonal perovskite structure. A minute displacement of XRD peaks was detected in the diffraction spectra of Ni-doped PZT ceramic samples which when examined by size-strain plot (SSP) method revealed presence of homogenous strain that decreased with increase in concentration of Ni. In FTIR the maximum absorption at 597?cm^?1, 608?cm^?1, 611?cm^?1, 605 and 613?cm^?1 for Ni?=?0, 5, 10, 15 and 20?at%, respectively, confirmed the formation of perovskite structure in all the compositions and the slight shift suggests decrease in cell size on doping. The values of dielectric constant (ε′) & tanδ as a function of frequency and temperature were measured for the prepared ceramics and it revealed highest ever reported dielectric constant for Ni - doped PZT with Ni?=?5?at%. The dielectric variation with temperature exhibited a diffused type ferroelectric–paraelectric phase transition for the doped samples. Also, the maximum dielectric constant value (ε′_max) decreased while the phase transition temperature increased with increase in doping concentration of Ni. The estimated activation energy of different compositions was found to increase from 0.057 to 0.068?eV for x?=?0.00 to x?=?0.20 in ferroelectric phase. The piezoelectric, ferroelectric and magnetic properties were also investigated.     

Preliminary Model and Technology of Piezoelectric Low Temperature Co‐fired Ceramic (LTCC) Uniaxial Accelerometer

Design procedure, technology and basic properties of a piezoelectric Low Temperature Co‐fired Ceramics (LTCC) accelerometer are presented in this paper. The sensor consists of a LTCC membrane with a seismic mass. Meggitt InSensor^® PZT thick film has been applied as the sensing material. Finite element method (FEM) has been used to analyze the impact of the sensor geometry (membrane thickness, membrane and seismic mass radii) and PZT thick film placement on basic properties (sensitivity and bandwidth) of the device. The LTCC process was optimized in order to create thin and planar ceramic membrane with relatively huge seismic mass. Selected properties of the sensor have been measured and compared with the simulated ones.     

Ferroelectric hysteresis behavior and dielectric properties of 1–3 lead zirconate titanate–cement composites

Lead zirconate titanate (PZT) ceramic was mixed with Portland cement (PC) to form 1–3 connectivity PZT–PC composite using a dice-and-fill technique. Ferroelectric hysteresis behavior and dielectric properties of these composites were investigated using PZT volume content of 60%, 70% and 80%. The results showed that the dielectric constant of the composite materials increased with PZT content and the dielectric constant (?_r) value is 781 for 80% PZT composite at 1 kHz. The dielectric loss tangent (tan δ) was found to decrease with increasing PZT content and the tan δ value of 80% PZT composite is 0.06. Parallel and series models were also compared to the dielectric measurement results. For the hysteresis measurements, the ferroelectric hysteresis loops can be seen for all composites. The “instantaneous” remnant polarization (P_ir) was found to increase with increasing PZT content from 3.20 to 4.28 μC/cm² at 90 Hz when PZT volume content used was 60% and 80% respectively.     

Effect of pore size and porosity on piezoelectric and acoustic properties of Pb(Zr0.53Ti0.47)O3 ceramics

We studied the effect of porosity and pore morphology on the functional properties of Pb(Zr_0.53Ti_0.47)O₃ (PZT) ceramics for application in high frequency ultrasound transducers. By sintering a powder mixture of PZT and polymethylmetacrylate spherical particles (1.5 and 10?μm) at 1080°C, we prepared ceramics with ～30% porosity with interconnected micrometer sized pores and with predominantly ～8?μm spherical pores. The acoustic impedance was ～15?MRa for both samples, which was lower than for the dense PZT. The attenuation coefficient α (at 2.25?MHz) was higher for ceramics with ～8?μm pores (0.96?dB?mm^??1?MHz^??1), in comparison to the ceramic with smaller pores (0.56?dB?mm^??1?MHz^??1). The high α value enables the miniaturisation of the transducer, which is crucial for medical imaging probes. The dielectric and piezoelectric coefficients, polarisation, and strain response decreased with increased porosity and decreased pore/grain size. We suggest a possible role of pore/grain size on the switching behaviour.     

Structural and piezoelectric properties of <001> textured PZT‐PZNN piezoelectric ceramics

Rhombohedral 0.69Pb(Zr_0.47Ti_0.53)‐0.31Pb(Zn_0.6Ni_0.4)NbO₃ (PZT‐PZNN) ceramics were textured using 10.0 vol. % BaTiO₃ (BT) platelets along the <001> direction at 950°C with a high Lotgering factor of 95.3%. BT platelets did not react with the PZT‐PZNN ceramics, and the textured PZT‐PZNN ceramic had a tetragonal structure. The PZT‐PZNN ceramics exhibited a strain of 0.174% with a piezoelectric strain constant (d*₃₃) of 580 pC/N at 3.0 kV/mm. The textured PZT‐PZNN ceramic showed an increased strain of 0.276% and d*₃₃ of 920 pC/N at 3.0 kV/mm, which can be explained by the domain rotation. However, the d₃₃ values of the textured specimens are smaller than those of the untextured specimens because of the small remanent polarization and relative dielectric constant of BT platelets. The textured PZT‐PZNN ceramic synthesized in this work can be used for piezoelectric multilayer actuators because of its large strain and low sintering temperature.     

PVDF‐PZT‐5H composites prepared by hot press and tape casting techniques

Piezoelectric polymer–ceramic composites are promising materials for transducer applications, and they are widely used in underwater hydrophones, biomedical imaging with ultrasound, and nondestructive testing applications. The critical factor in the 0–3 composite is to ensure homogeneous distribution of the filler in the matrix. To ensure this objective, PVDF‐PZT composite was prepared by two different routes: hot press and tape casting techniques. Loss on ignition and scanning electron microscopy studies were conducted to find out the uniformity of the composites prepared. It is found that hot press technique gives better uniformity compared to tape casting technique. PZT concentration was varied from 20 to 60 vol %. Physical and dielectric properties were studied. FT‐IR, DSC, and XRD characterization studies of PVDF were also recorded. Density of the composites was 2.74 to 5.13 g/cm³ as PZT concentration increased from 20 to 60 volume fractions. The dielectric constant of composites at 1 MHz varied from 16.74 to 98.48 as PZT concentration increased from 20 to 60 volume fractions. Hot press technique that combines solution and melt processing was found to be the better method for the preparation of 0–3 composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Electrostrictive Properties of the lead Zirconate Titanate Solid-Solution System

Values of the electrostrictive constants for the lead zirconate titanate (PZT) solid-solution system were required to com plete the development of a thermodynamic phenomenological theory of PZT. The electrostrictive ₁₂ constant was meas ured as a function of composition on polycrystalline ceramic PZT samples. These data were used with additional single–crystal and ceramic data from the literature to approximate the compositional dependence of the electrostrictive constants of the PZT system. Series and parallel equations, analogous to the Voigt and Reuss models for the elastic constants, were used to relate the ceramic and single-crystal data, and to pre dict the upper and lower bounds of the ceramic electrostric tive constants from the single-crystal constants.     

Magnetoelectric Response in (1−x)PbZr0.65Ti0.35O3–xBaFe12O19 Multiferroic Ceramic Composites

The magnetoelectric (ME) properties of PbZr_0.65Ti_0.35O₃–BaFe₁₂O₁₉ (PZT–BaM) multiferroic ceramic composites have been investigated in this work. These materials, containing both the ferroelectric PZT and ferrimagnetic BaM phases, were prepared from the conventional solid‐state reaction method, and their main (micro)structural characteristics are provided. The ME measurements were performed over wide frequency and temperature ranges, and the influence of the BaM content was appraised. An enhanced ME coefficient (α) was obtained for the applied magnetic field of 0.8 kOe, at 97 kHz. In addition, the results reveal a high thermal stability of α in the whole analyzed temperature range, showing that the studied PZT‐based ceramic composites have great potential for practical applications.     

Rapid Prototyping of Piezoelectric Ceramics via Selective Laser Sintering and Gelcasting

This article presents a new lost mold rapid prototyping method which combines selective laser sintering (SLS) and gelcasting techniques for fabricating piezoelectric ceramics. SLS was used to fabricate sacrificial molds of the desired structure of the ceramic part. Then aqueous PZT (lead zirconate titanate) suspension was cast in the mold and solidified in situ through formation of a three-dimensional network gel. Because the polymer mold can be easily removed at the initial stage of sintering and the gelcast PZT body has a high green strength, the desired geometry of the PZT part can be completely retained after sintering of the ceramics. Complex-shaped PZT parts were successfully fabricated after using concentrated PZT suspension with low viscosity. Densities and electrical properties, such as the d ₃₃, the relative permittivity ε, the dielectric loss tg δ and the electromechanical coupling factor K _p of the gelcast PZT parts were also compared with those of the die-pressed PZT samples. The results indicated that the gel-forming process did not deteriorate the electrical properties of the samples, if proper dispersant was selected in developing concentrated ceramic slurry.     

ZnO surface modified PZT for enhanced ceramic composite thick film sensors

Abstract

Abstract

Acoustic emission (AE) sensors are capable of detecting elastic waves emitted when cracks advance in engineering structures. To provide real time continuous monitoring, such sensors would have to remain permanently in place, but this is uneconomic and impractical to realise in many situations. The availability of low cost and small AE sensors is hampered by the poor piezoelectric properties of materials that can easily be processed and the processing challenges associated with materials that exhibit high piezoelectric properties. Here, a ZnO surface treatment for lead zirconate titanate (PZT) ceramic particles is presented that enhances the interfacial bonding between PZT and polymer to allow mechanically robust composite films to be created that exhibit d₃₃ piezoelectric coefficient of 15 pC/N after corona poling at 100°C. Films of modified PZT–polymer material have been used to detect simulated acoustic emission events. A comparison between such devices and commercially available PZT ceramic based devices is drawn.     

A study of the electric power generation properties of a lead zirconate titanate piezoelectric ceramic

Electric power generation characteristics of lead zirconate titanate (PZT) piezoelectric ceramic have been investigated experimentally and numerically. A thin PZT ceramic plate attached to a thin brass plate was used to examine the electric voltage generated during cyclic loading. On increasing the number of PZT ceramic plates combined together in the longitudinal direction, the electric voltage increases with the highest electric voltage being obtained for four PZT ceramic plates; and the maximum electric voltage becomes almost constant even if the number of PZT ceramic plates combined together increases more than four. This is attributed to the low strain level and the mixed strain (compressive and tensile strain). The effect of strain characteristic on the electric voltage value was analyzed numerically using our strain definition, and a clear correlation between the extent of compressive strain and generated electric voltage is clarified. A different electric generation characteristic was further observed depending on the stress conditions: generation of positive and negative electric voltage occurs when the PZT ceramic is subjected to mainly compressive and tensile stress, respectively.     

Fabrication of 1–3 piezoelectric composites via modified soft mold process for 40 MHz ultrasonic medical transducers

High performance 1–3 piezocomposites are important components of high-frequency ultrasound transducers, which are used for the medical imaging of fine structures in human tissues. In this study, a modified soft mold process was developed for the fabrication of lead zirconate titanate (PZT) ceramic 1–3 piezocomposites by compressing soft mold with powder. First, the piezocomposite structures were designed and optimized for high-frequency applications at 40 MHz via finite element analysis (FEA). Then, 1–3 piezocomposites were fabricated through a soft mold process, with PZT pillars as small as 25 μm in diameter. The morphology, phase composition, homogeneity, and microstructure of the obtained 1–3 piezocomposites were investigated using SEM, XRD and Raman spectroscopy analyses. The dielectric, piezoelectric, and acoustic properties of the 1–3 piezocomposites were measured to verify the efficacy of the soft mold technology. The present work introduces an effective and cost-effective strategy for fabricating 1–3 piezocomposites with excellent electromechanical performance for high-frequency transducers, which can be used in the fields of medical imaging and ultrasound biomicroscopy.     

Liquid-phase sintering of PZT ceramics

Lead zirconate titanate (abbreviated as PZT) ceramics are of considerable commercial importance for a host of piezoelectric and pyroelectric applications. Conventionally, many PZT ceramics are sintered at temperatures above 1250°C. Such extreme temperatures are undesirable due to the increased energy consumption, limitation of electrode material and evaporation of volatile components. A liquid-phase sintering aid incorporating Cu₂O and PbO is presented which demonstrates a reduction in the required sintering temperature of these ceramics. This new aid is described with particular reference to a commercial PZT, termed Pz26, used industrially for its optimised piezoelectric properties. Pz26 has a composition near the morphotropic phase boundary and possesses a tetragonal crystalline structure. Typically this material is sintered between 1260 and 1300°C for 1 h to achieve the required densification. With the inclusion of sintering aid, sintered densities comparable to those obtained by conventional sintering are achieved at only 800°C. The optimum weight percentage of sintering aid varies for different ceramic materials, particle sizes, morphology and the desired sintering temperature. However, with standard “mixed-oxide” produced Pz26 powder and with a median particle size in the range 1.6–1.7 μm, a value of 5 wt.% allows sintering at 800°C, according to densification, dielectric and piezoelectric measurements (ϵ=873, tan δ=1.13 %, k_p=43.1%). When finer grained powder is used (d_0.5=1.1 μm), improved properties (ϵ=960, tan δ=1.04%, k_p=51.7%) are obtained for an addition of 3 wt.% sintering aid and a sintering temperature of 850°C.