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Piezoelectric Coefficient (piezoelectric + coefficient)
Selected AbstractsLarge Piezoelectric Coefficient in Tb-Doped BiFeO3 FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2010Xuemei Chen Polycrystalline BiFeO3 and Bi1,xTbxFeO3 (BTFO) (x=0.05,0.16) thin films were deposited on indium tin oxide/glass substrates via a metal organic deposition method. The influence of Tb doping content on the structure and multiferroic properties was investigated. X-ray diffraction results reveal that there may exist a structure transition around x=0.11 in the BTFO system. Well-saturated and rectangular P,E hysteresis loops can be observed in all BTFO films. The BTFOx=0.11 film exhibits the maximum values of the remanent out-of-plane piezoelectric coefficient (d33=140 pm/V) and saturated magnetization (Ms=22.2 emu/cm3). [source] Domain Engineering of Lead-Free Li-Modified (K,Na)NbO3 Polycrystals with Highly Enhanced PiezoelectricityADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Ke Wang Abstract Aging and re-poling induced enhancement of piezoelectricity are found in (K,Na)NbO3 (KNN)-based lead-free piezoelectric ceramics. For a compositionally optimized Li-doped composition, its piezoelectric coefficient d33 can be increased up to 324 pC N,1 even from a considerably high value (190 pC N,1) by means of a re-poling treatment after room-temperature aging. Such a high d33 value is only reachable in KNN ceramics with complicated modifications using Ta and Sb dopants. High-angle X-ray diffraction analysis reveals apparent changes in the crystallographic orientations related to a 90° domain switching before and after the aging and re-poling process. A possible mechanism considering both defect migration and rotation of spontaneous polarization explains the experimental results. The present study provides a general approach towards piezoelectric response enhancement in KNN-based piezoelectric ceramics. [source] Universal Behavior and Electric-Field-Induced Structural Transition in Rare-Earth-Substituted BiFeO3ADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Daisuke Kan Abstract The discovery of a universal behavior in rare-earth (RE)-substituted perovskite BiFeO3 is reported. The structural transition from the ferroelectric rhombohedral phase to an orthorhombic phase exhibiting a double-polarization hysteresis loop and substantially enhanced electromechanical properties is found to occur independent of the RE dopant species. The structural transition can be universally achieved by controlling the average ionic radius of the A-site cation. Using calculations based on first principles, the energy landscape of BiFeO3 is explored, and it is proposed that the origin of the double hysteresis loop and the concomitant enhancement in the piezoelectric coefficient is an electric-field-induced transformation from a paraelectric orthorhombic phase to the polar rhombohedral phase. [source] Preparation of Oriented Aluminum Nitride Thin Films on Polyimide Films and Piezoelectric Response with High Thermal Stability and FlexibilityADVANCED FUNCTIONAL MATERIALS, Issue 3 2007M. Akiyama Abstract c -Axis oriented aluminum nitride (AlN) thin films are successfully prepared on amorphous polyimide films by radiofrequency magnetron reactive sputtering at room temperature. Structural analysis shows that the AlN films have a wurtzite structure and consist of c -axis oriented columnar grains about 100,nm wide. The full width at half maximum of the X-ray diffraction rocking curves and piezoelectric coefficient d33 of the AlN films are 8.3° and 0.56,pC,N,1, respectively. The AlN films exhibit a piezoelectric response over a wide temperature range, from ,196 to 300,°C, and can measure pressure within a wide range, from pulse waves of hundreds of pascals to 40,MPa. Moreover, the sensitivity of the AlN films increases with the number of times it was folded, suggesting that we can control the sensitivity of the AlN films by changing the geometric form. These results were achieved by a combination of preparing the oriented AlN thin films on polyimide films, and sandwiching the AlN and polymer films between top and bottom electrodes, such as Pt/AlN/polyimide/Pt. They are thin (less than 10,,m), self powered, adaptable to complex contours, and available in a variety of configurations. Although AlN is a piezoelectric ceramic, the AlN films are flexible and excellent in mechanical shock resistance. [source] Fabrication of Microcantilever Sensors Actuated by Piezoelectric Pb(Zr0.52Ti0.48)O3 Thick Films and Determination of Their Electromechanical Characteristics,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2005H. Park Abstract The integration and the device realization of Pb(Zr,,Ti)O3 (PZT) thick films on Si substrates are known to be extremely difficult because the processing temperature of the PZT thick film is close to the melting point of Si. However, PZT thick-film devices on Si warrant attention as they are appropriate for biological transducers; they generate large actuating forces and have a relatively high sensitivity for mass detection, especially in liquids. In this study, Pb(Zr0.52Ti0.48)O3 thick-film cantilever devices are successfully fabricated on a Pt/TiO2/SiNx/Si substrate using a screen-printing method and microelectromechanical systems (MEMS) process. Elastic and electromechanical properties such as the Young's modulus and transverse piezoelectric coefficient are determined from microstructural and electrical analyses for further mechanical study. The calculated Young's modulus of the thick film, 53.9,±,3.85,GPa, corresponds to the resonant frequency obtained from the measured harmonic oscillation response. The transverse piezoelectric constant, d31, of ,20.7 to ,18.8,pC,N,1 is comparable to that of a dense thin film. These values promise the possibility of determining the resonance properties of a thick-film cantilever by designing its structure and then simulating the harmonic oscillation response. Using the PZT thick-film cantilever, a strong harmonic oscillation with a quality (Q) factor of about 23 is demonstrated in water. The observation of strong harmonic oscillation in liquid implies the feasibility of precise real-time recognition of biomolecules using PZT thick-film cantilevers. [source] Labile Ferroelastic Nanodomains in Bilayered Ferroelectric Thin FilmsADVANCED MATERIALS, Issue 34 2009Varatharajan Anbusathaiah Bilayered Pb(Zr(1,x),Tix)O3 ferroelectric thin film heterostructures show complex ferroelastic nanodomain patterns. These ferroelastic nanodomains exist only in the upper layer, and hence are able to move under the application of an external electric field. Quantitative analysis reveals an enhanced piezoelectric coefficient of ,220 pm V,1, rendering them attractive for a variety of electromechanical devices. [source] Intrinsic Ferroelectric Properties of Strained Tetragonal PbZr0.2Ti0.8O3 Obtained on Layer,by,Layer Grown, Defect,Free Single,Crystalline Films,ADVANCED MATERIALS, Issue 13 2006I. Vrejoiu Ferroelectric single,crystalline PbZr0.2Ti0.8O3 thin films, free from extended defects, are grown by pulsed laser deposition onto vicinal SrTiO3(001) single crystals. The PbZr0.2Ti0.8O3 films are strained and exhibit enhanced tetragonality, c/a,,,1.06. They have a remnant polarization, Pr,,,110,,C,cm,2, dielectric constant, ,33,,,90, and piezoelectric coefficient, d33, up to 50,pm,V,1 (see figure). [source] Phase Characteristics and Piezoelectric Properties in the Bi0.5Na0.5TiO3,BaTiO3,K0.5Na0.5NbO3 SystemJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2010Shan-Tao Zhang Lead-free 0.94Bi0.5Na0.5TiO3,(0.06,x)BaTiO3,xK0.5Na0.5NbO3 (x=0,0.06) ceramics were prepared. All these compositions have a structure close to the rhombohedral,tetragonal morphotropic phase boundary (MPB) and good electric properties at room temperature. No significant composition dependence of ferroelectric property can be established, whereas a dependence of piezoelectric properties can be observed, e.g. the piezoelectric coefficient (d33), planar coupling factor (kp), and field-induced strain (S) increase with increasing x when x,0.01 and then tend to decrease. The highest d33, kp, and bipolar strain are 118 pC/N, 0.29, and 0.32%, respectively, in the composition with x=0.01. The results not only indicate that BNT,BT,KNN lead-free piezoceramics can persist in the structure close to MPB in a wide composition range but that they may also be helpful for further investigation on lead-free piezoceramics. [source] Large Piezoelectric Coefficient in Tb-Doped BiFeO3 FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2010Xuemei Chen Polycrystalline BiFeO3 and Bi1,xTbxFeO3 (BTFO) (x=0.05,0.16) thin films were deposited on indium tin oxide/glass substrates via a metal organic deposition method. The influence of Tb doping content on the structure and multiferroic properties was investigated. X-ray diffraction results reveal that there may exist a structure transition around x=0.11 in the BTFO system. Well-saturated and rectangular P,E hysteresis loops can be observed in all BTFO films. The BTFOx=0.11 film exhibits the maximum values of the remanent out-of-plane piezoelectric coefficient (d33=140 pm/V) and saturated magnetization (Ms=22.2 emu/cm3). [source] Effect of A Site Substitution on the Properties of CaBi2Nb2O9 Ferroelectric CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2008Xiaodong Zhang The effect of A-site substitution on the piezoelectric coefficient, high-temperature dc resistivity, and thermal depoling behavior of Aurivillius phase CaBi2Nb2O9 ferroelectric ceramics was investigated. Ceramics with the general formula of Ca1,xMxBi2Nb2O9, where M=Na, (Na,Ce), (Na,La), and La, were prepared by conventional solid-state sintering. All the ceramics were single-phase ferroelectrics with high Curie points (,900°C). The doped ceramics, Ca0.9Na0.1Bi2Nb2O9, Ca0.9(NaLa)0.1Bi2Nb2O9, Ca0.95La0.05Bi2Nb2O9, and Ca0.9La0.1Bi2Nb2O9, had improved resistance to thermal depoling compared with Ca2Bi2Nb2O9 and were stable up to 800°C. The donor dopants increased the dc electrical resistivity, while the acceptor dopants decreased it. The donor-doped Ca0.95La0.05Bi2Nb2O9 had a higher piezoelectric constant (d33=12.8 pC/N) compared with CaBi2Nb2O9 (d33=5.8 pC/N), and its electrical resistivity was higher than 106,·cm at 600°C. These properties suggest that doped CaBi2Nb2O9 ceramics might be good candidates for high-temperature piezoelectric applications. [source] A Novel Hybrid Method of Sol,Gel and Ultrasonic Atomization Synthesis and Piezoelectric Properties of SrBi4Ti4O15 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2008Zhijun Xu SrBi4Ti4O15(SBTi) powders were synthesized by a novel hybrid method of sol,gel and ultrasonic atomization. TiO2 particle was used as a starting material to replace other expensive soluble titanium salts. X-ray diffraction results showed that the pure-phase SBTi powders were obtained at 700°C for 2 h, which is much lower than the calcination temperature (800°,850°C) required in solid-state reactions. The ceramics sintered at 1100°C for 1 h exhibited 94.5% of relative density and a piezoelectric coefficient of 21 pC/N. The results showed that this hybrid method could lead to an attractive method for the industrial fabrication of SBTi materials. [source] Properties of Compositionally Graded BiScO3,PbTiO3 Thin Films Fabricated by a Sol,Gel ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2007Hai Wen The compositionally graded BiScO3,PbTiO3 (BSPT) thin films were fabricated on Pt/Ti/SiO2/Si by a sol,gel method. For the up-graded thin film, the PbTiO3 content increased from the film,substrate interface to the surface of the film, while the down-grade thin film showed the opposite trend. The graded thin films exhibited single-phase structures and dense microstructures. The dielectric and ferroelectric properties of the thin films were investigated. The results showed that the compositionally graded BSPT thin films had similar remanent polarization value but a higher dielectric constant, dielectric tunability, and piezoelectric coefficient d33 compared with the homogeneous thin film with a composition of 0.36BiScO3,0.64PbTiO3 at the morphotropic phase boundary. [source] Lead-free piezoelectric (Na0.5Bi0.5)0.94TiO3,Ba0.06TiO3 nanofiber by electrospinningPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 9 2009Y. Q. Chen Abstract Lead-free (Na0.5Bi0.5)0.94TiO3,Ba0.06TiO3 (NBT-BT6) nanofibers were synthesized by the sol,gel process and electrospinning, and a butterfly-shaped piezoelectric response was measured by scanning force microscopy. NBT-BT6 nanofibers with perovskite phase were formed, after being cleaned at 700 °C for 1 hour, and the diameters are in the range of 150 nm to 300 nm. The average value of the effective piezoelectric coefficient d33 is 102 pm/V. The high piezoelectricity may be attributed to the easiness for the electric field to tilt the polar vector of the domain and to the increase of the possible spontaneous polarization direction. There is a potential for the application of NBT-BT6 nanofibers in nanoscale piezoelectric devices. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of heat treatment on the electrical properties of lead zirconate titanate/poly (vinylidene fluoride) compositesPOLYMER INTERNATIONAL, Issue 6 2010Lijie Dong Abstract 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 (,) of 165 and a low dielectric loss (tan ,) 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 [source] | ||||||||||