共查询到20条相似文献,搜索用时 46 毫秒
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Chen Y Jiang XP Luo HS Dai JY Chan HL 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2010,57(11):2601-2604
High-frequency (25 MHz) ultrasonic transducers with Na(0.5)Bi(0.5)TiO(3)-BaTiO(3) (NBT-BT) lead-free piezoelectric single crystal as the active elements are fabricated and characterized. The impedance measurement reveals that the poled [001]-oriented NBT-BT single crystal exhibits a high thickness electromechanical coefficient k(t) of 0.52 and a low clamped dielectric constant of 80. The -6-dB bandwidth of the transducer is 46.16% and the insertion loss at the center frequency is -31.89 dB. The good performance of the transducer indicates that the NBT-BT single crystal would be a promising lead-free material for ultrasonic transducer applications. 相似文献
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Shujun Zhang Thomas R Shrout Hajime Nagata Yuji Hiruma Tadashi Takenaka 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(5):910-917
Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na0.5Bi0.5)TiO3-y(K0.5Bi0.5)TiO3-zBaTiO3 [x + y + z = 1; y:z = 2:1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280 degrees C and 262 degrees C were found for tetragonal 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Bi0.5)TiO3-0.07BaTiO3 (BNBK79) and MPB composition 0.88(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3-0.04BaTiO3 (BNBK88), with depolarization temperatures of 224 degrees C and 162 degrees C, respectively. Piezoelectric coefficients d33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d31 was determined to be -37 pC/N and -51 pC/N, demonstrating strong anisotropy. Coercive field values were found to be 37 kV/cm and 29 kV/cm for BNBK79 and BNBK88, respectively. The remanent polarization of BNBK88 (approximately 40 microC/cm2) was larger than that of BNBK79 (approximately 29 microC/cm2). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed. 相似文献
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Lam KH Lin DM Kwok KW Lai-Wa Chan H 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(8):1682-1685
A piezoelectric piezoelectric-metal-cavity (PMC) actuator was reported previously that can exhibit a large flexural displacement. In this paper, a lead-free piezoelectric ceramic was used as a driving element of the PMC actuator. Bi(0.5)(Na(0.725)K(0.175)Li(0.1))(0.5)TiO3 (abbreviated as BNKLT) is a soft-type piezoelectric ceramic with good piezoelectric properties at room temperature. Both the electrical and mechanical properties of the BNKLT PMC actuator were measured. With good piezoelectric coefficients and low density, the BNKLT ceramic has the potential to be used as the driving element of the lead-free actuator. 相似文献
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This paper presents the fabrication and characterization of single-element ultrasonic transducers whose active elements are made of lead-free piezoceramic, 1-3 PZT/polymer composite and PVDF film. The lead free piezoelectric KNNLT- LS(K0.44Na0.52Li0.04)(Nb0.84Ta0.10S0.06b)O3 powders and ceramics were prepared under controlled humidity and oxygen flow rate during sintering. Due to its moderate longitudinal piezoelectric charge coefficient (175 pC/N) and kt of 0.50, the KNN-LT-LS composition may be a good candidate for highfrequency transducer applications. PZT fibers with 25 μm diameter formed by the viscose suspension spinning process were incorporated into epoxy to fabricate 1-3 composites with the averaged kt = 0.64 and d33 = 400 pC/N. Using KNN-LS-LT ceramic, 1-3 PZT fiber composite, and PVDF film, 3 different unfocused single element transducers with center frequencies of 25 MHz were fabricated. The acoustic characterization of the transducers demonstrated that wideband and low insertion loss could be obtained employing KNN-LS-LT ceramic. The ?6 dB bandwidth and insertion loss were 70% and ?21 dB, respectively. In comparison, the insertion loss of the ceramic transducer was much smaller than those made with 1-3 composite and PVDF film. This was attributed to closer electrical impedance match to 50 Ω and higher thickness coupling coefficient of the ceramic transducer. 相似文献
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Zhou D Cheung KF Chen Y Lau ST Zhou Q Shung KK Luo HS Dai J Chan HL 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(2):477-484
In this paper, 0.7Pb(Mg(1/?)Nb(2/?)O?-0.3PbTiO? (PMN-PT) single crystal/epoxy 1/3 composite was used as the active material of the endoscopic ultrasonic radial array transducer, because this composite exhibited ultrahigh electromechanical coupling coefficient (k(t) = 0.81%), very low mechanical quality factor (Q(m) = 11) and relatively low acoustic impedance (Z(t) = 12 MRayls). A 6.91 MHz PMN-PT/epoxy 1/3 composite radial array transducer with 64 elements was tested in a pulseecho response measurement. The -6-dB bandwidth of the composite array transducer was 102%, which was ~30% larger than that of traditional lead zirconate titanate array transducer. The two-way insertion loss was found to be -32.3 dB. The obtained results show that this broadband array transducer is promising for acquiring high-resolution endoscopic ultrasonic images in many clinical applications. 相似文献
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Yunwen Liao ) Dingquan Xiao) ) Institute of Applied Chemistry China West Normal University Nanchong China ) 《材料科学技术学报》2009,(6)
Lead-free piezoelectric ceramics (1-y)Bi0.5(Na1-xLix)0.5TiO3-yBaTiO3 with x=0-0.125 and y=0.02-0.12 were fabricated by a solid-state reaction process, and their dielectric, piezoelectric and ferroelectric properties were investigated. The results show that the addition of Li+ significantly improves the sintering performance and piezoelectric properties of the ceramics. X-ray diffraction (XRD) patterns indicate that the ceramics possess pure perovskite structure. At room temperature, the ceramics provide hig... 相似文献
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Lau ST Ji HF Li X Ren W Zhou Q Shung KK 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(1):249-254
Lead-free K(0.5)Na(0.5)NbO(3)/Bi(0.5)Na(0.5)TiO(3) (KNN/ BNT) films have been fabricated by a composite sol-gel technique. Crystalline KNN fine powder was dispersed in the BNT precursor solution to form a composite slurry which was then spin-coated onto a platinum-buffered Si substrate. Repeated layering and vacuum infiltration were applied to produce 5-μm-thick dense composite film. By optimizing the sintering temperature, the films exhibited good dielectric and ferroelectric properties comparable to PZT films. A 193-MHz high-frequency ultrasonic transducer fabricated from this composite film showed a -6-dB bandwidth of approximately 34%. A tungsten wire phantom was imaged to demonstrate the capability of the transducer. 相似文献
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BNT-BT和BNT-BKT基无铅压电陶瓷研究进展 总被引:6,自引:1,他引:5
综述了Bi0.5Na0.5TiO3-BaTiO3系和Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3系无铅压电陶瓷的最新研究进展.总结了各种添加剂对这两种无铅压电陶瓷体系压电性能的影响机理和规律,介绍了当前以各种工艺对其微观结构和压电性能进行改进的研究成果,并展望了这两种无铅压电陶瓷体系的发展趋势. 相似文献
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Liu R Harasiewicz KA Foster FS 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2001,48(1):299-306
Interdigital pair bonding is a novel methodology that enables the fabrication of high frequency piezoelectric composites with high volume fractions of the ceramic phase. This enhancement in ceramic volume fraction significantly reduces the dimensional scale of the epoxy phase and increases the related effective physical parameters of the composite, such as dielectric constant and the longitudinal sound velocity, which are major concerns in the development of high frequency piezoelectric composites. In this paper, a method called interdigital pair bonding (IPB) is used to prepare 1-3 piezoelectric composite with a pitch of 40 microns, a kerf of 4 microns, and a ceramic volume fraction of 81%. The composites prepared in this fashion exhibited a very pure thickness-mode resonance up to a frequency of 50 MHz. Unlike the 2-2 piezoelectric composites with the same ceramic and epoxy scales developed earlier, the anticipated lateral modes between 50 to 100 MHz were not observed in the current 1-3 composites. The mechanisms for the elimination of the lateral modes at high frequency are discussed. The effective electromechanical coupling coefficient of the composite was 0.72 at a frequency of 50 MHz. The composites showed a high longitudinal sound velocity of 4300 m/s and a high clamped dielectric constant of 1111 epsilon 0, which will benefit the development of high frequency ultrasonic transducers and especially high frequency transducer arrays for medical imaging. 相似文献
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Zhou Q Xu X Gottlieb EJ Sun L Cannata JM Ameri H Humayun MS Han P Shung KK 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(3):668-675
High-frequency needle ultrasound transducers with an aperture size of 0.4 mm were fabricated using lead magnesium niobate-lead titanate (PMN-33% PT) as the active piezoelectric material. The active element was bonded to a conductive silver particle matching layer and a conductive epoxy backing through direct contact curing. An outer matching layer of parylene was formed by vapor deposition. The active element was housed within a polyimide tube and a 20-gauge needle housing. The magnitude and phase of the electrical impedance of the transducer were 47 omega and -38 degrees, respectively. The measured center frequency and -6 dB fractional bandwidth of the PMN-PT needle transducer were 44 MHz and 45%, respectively. The two-way insertion loss was approximately 15 dB. In vivo high-frequency, pulsed-wave Doppler patterns of blood flow in the posterior portion and in vitro ultrasonic backscatter microscope (UBM) images of the rabbit eye were obtained with the 44-MHz needle transducer. 相似文献
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以(Na0.5Bi0.5)0.94Ba0.06TiO3为基体,研究了单、双组分掺杂La2O3、Y2O3对BNBT6陶瓷的压电和介电性能及微观结构的影响。XRD分析表明:掺杂La2O3、Y2O3均得到钙钛矿结构。SEM分析表明,分别掺杂0.2%La2O3和0.2%Y2O3使得陶瓷晶粒增大,压电常数提高,双组分掺杂La2O3、Y2O3在掺杂量0.12%La2O3+0.08%Y2O3时,压电常数d33增大到最大值144.6×10-12C/N,介质损耗降低到最小值0.039。 相似文献
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Wu M Wang Y Wang D Li Y 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(10):2036-2041
(001)(pc)-oriented (Na(0.5)Bi(0.5))(0.94)Ba(0.06)TiO(3) (NBBT) lead-free piezoelectric ceramics were fabricated by the screen printing technique using Na(0.5)Bi(0.5)TiO(3) (NBT) templates. The plate-like NBT template particles were synthesized from bismuth layer-structured ferroelectric Bi(4)Ti(3)O(12) (BiT) precursors by the topochemical method. The screen printed NBBT ceramics with 20 wt% NBT templates contained a large fraction of grains aligned with their c-axis normal to the sample surface, giving a Lotgering factor of 0.486. The dielectric and ferroelectric properties of textured NBBT ceramics were anisotropic. Compared with the non-textured NBBT ceramics, the dielectric, ferroelectric, and piezoelectric properties of the textured NBBT ceramics were improved, giving a dielectric constant ?(T)(33)/?(0) of 910, a remnant polarization P(r) of 29.2 μC/cm(2), a coercive field E(c) of 23.5 kV/cm, a piezoelectric coefficient d(33) of 180 pC/N, and a thickness-mode electromechanical coupling coefficient k(t) of 0.485. 相似文献
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Ketterling JA Aristizábal O Turnbull DH Lizzi FL 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2005,52(4):672-681
This paper investigates the feasibility of fabricating a five-ring, focused annular array transducer operating at 40 MHz. The active piezoelectric material of the transducer was a 9-microm thick polyvinylidene fluoride (PVDF) film. One side of the PVDF was metallized with gold and forms the ground plane of the transducer. The array pattern of the transducer and electrical traces to each annulus were formed on a copper-clad polyimide film. The PVDF and polyimide were bonded with a thin layer of epoxy, pressed into a spherically curved shape, then back filled with epoxy. A five-ring transducer with equal area elements and 100-microm kerfs between annuli was fabricated and tested. The transducer had a total aperture of 6 mm and a geometric focus of 12 mm. The pulse/echo response from a quartz plate located at the geometric focus, two-way insertion loss (IL), complex impedance, electrical crosstalk, and lateral beamwidth all were measured for each annulus. The complex impedance data from each element were used to perform electrical matching, and the measurements were repeated. After impedance matching; fc approximately equal to 36 MHz and -6-dB bandwidths ranged from 31 to 39%. The ILs for the matched annuli ranged from -28 to -38 dB. 相似文献