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1

Lead-free multilayer piezoelectric transformer  

Microsoft Academic Search

In this article, a multilayer piezoelectric transformer based on lead-free Mn-doped 0.94(Bi1\\/2Na1\\/2)TiO3-0.06BaTiO3 ceramics is presented. This piezoelectric transformer, with a multilayered construction in the thickness direction, is 8.3 mm long, 8.3 mm wide, and 2.3 mm thick. It operates in the second thickness extensional vibration mode. For a temperature rise of 20 °C, the transformer has an output power of

Mingsen Guo; X. P. Jiang; K. H. Lam; S. Wang; C. L. Sun; Helen L. W. Chan; X. Z. Zhao

2007-01-01

2

Preparation and Characterization of Lead-free Piezoelectric Ceramics Qiang Chen1,a  

E-print Network

Preparation and Characterization of Lead-free Piezoelectric Ceramics Qiang Chen1,a , Jinxu Li1,b properties; Perovskites; (K,Na)NbO3 Abstract. (K,Na)NbO3-based piezoelectric ceramics are promising piezoelectric properties. In this paper, lead-free piezoelectric ceramics (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0

Volinsky, Alex A.

3

Structure and piezoelectric properties of lead-free bismuth-based perovskite solid solutions.  

E-print Network

??A new group of lead free piezoelectric perovskite solid solutions, (1-x)Bi(B'B")O?-xABO?, were obtained via solid-state processing techniques. The solubility of unstable perovskite Bi(B'B")O? compounds into… (more)

Huang, Chien-Chih

2008-01-01

4

A lead-free flexible structure for piezoelectric power generation  

NASA Astrophysics Data System (ADS)

Here, we demonstrate a fully-flexible piezoelectric hybrid structure composed of sodium niobate nanocubes and polyvinylidene fluoride. Hydrothermally-grown sodium niobate nanocubes show an orthorhombic crystal structure with Pmc21 symmetry, and polyvinylidene fluoride is electrically poled for the ?-phase, each of those represents piezoelectricity. Hybrid devices were electrically tested in two different modes by applying forces parallel to the in-plane and the out-of-plane directions of the piezoelectric layer. Our device shows an output voltage, current, and power density of 2.9 V, 68 nA, and 4.4 ?Wcm-3, respectively, at a pushing force of 5 kgf and a frequency of 1 Hz. The output power generation also shows a linear relation with the applied force over a wide range of 1-5 kgf. This implies our flexible hybrid piezoelectric structure can be adapted to various mechanical environments. Our unique structure should open up various application areas of piezoelectric materials such as touch sensors, flexible energy harvesters and eco-friendly piezoelectric actuators.

Kho, Byung Woo; Yun, Byung Kil; Jung, Jong Hoon; Lee, Minbaek

2014-06-01

5

Advances in Lead-Free Piezoelectric Materials for Sensors and Actuators  

PubMed Central

Piezoelectrics have widespread use in today’s sensor and actuator technologies. However, most commercially available piezoelectric materials, e.g., Pb [ZrxTi1?x] O3 (PZT), are comprised of more than 60 weight percent lead (Pb). Due to its harmful effects, there is a strong impetus to identify new lead-free replacement materials with comparable properties to those of PZT. This review highlights recent developments in several lead-free piezoelectric materials including BaTiO3, Na0.5Bi0.5TiO3, K0.5Bi0.5TiO3, Na0.5K0.5NbO3, and their solid solutions. The factors that contribute to strong piezoelectric behavior are described and a summary of the properties for the various systems is provided. PMID:22294907

Aksel, Elena; Jones, Jacob L.

2010-01-01

6

Giant piezoelectricity in potassium-sodium niobate lead-free ceramics.  

PubMed

Environment protection and human health concern is the driving force to eliminate the lead from commercial piezoelectric materials. In 2004, Saito et al. [ Saito et al., Nature , 2004 , 432 , 84 . ] developed an alkali niobate-based perovskite solid solution with a peak piezoelectric constant d33 of 416 pC/N when prepared in the textured polycrystalline form, intriguing the enthusiasm of developing high-performance lead-free piezoceramics. Although much attention has been paid on the alkali niobate-based system in the past ten years, no significant breakthrough in its d33 has yet been attained. Here, we report an alkali niobate-based lead-free piezoceramic with the largest d33 of ?490 pC/N ever reported so far using conventional solid-state method. In addition, this material system also exhibits excellent integrated performance with d33?390-490 pC/N and TC?217-304 °C by optimizing the compositions. This giant d33 of the alkali niobate-based lead-free piezoceramics is ascribed to not only the construction of a new rhombohedral-tetragonal phase boundary but also enhanced dielectric and ferroelectric properties. Our finding may pave the way for "lead-free at last". PMID:24499419

Wang, Xiaopeng; Wu, Jiagang; Xiao, Dingquan; Zhu, Jianguo; Cheng, Xiaojing; Zheng, Ting; Zhang, Binyu; Lou, Xiaojie; Wang, Xiangjian

2014-02-19

7

Lead-free LiNbO3 nanowire-based nanocomposite for piezoelectric power generation  

PubMed Central

In a flexible nanocomposite-based nanogenerator, in which piezoelectric nanostructures are mixed with polymers, important parameters to increase the output power include using long nanowires with high piezoelectricity and decreasing the dielectric constant of the nanocomposite. Here, we report on piezoelectric power generation from a lead-free LiNbO3 nanowire-based nanocomposite. Through ion exchange of ultra-long Na2Nb2O6-H2O nanowires, we synthesized long (approximately 50 ?m in length) single-crystalline LiNbO3 nanowires having a high piezoelectric coefficient (d33 approximately 25 pmV-1). By blending LiNbO3 nanowires with poly(dimethylsiloxane) (PDMS) polymer (volume ratio 1:100), we fabricated a flexible nanocomposite nanogenerator having a low dielectric constant (approximately 2.7). The nanogenerator generated stable electric power, even under excessive strain conditions (approximately 105 cycles). The different piezoelectric coefficients of d33 and d31 for LiNbO3 may have resulted in generated voltage and current for the e33 geometry that were 20 and 100 times larger than those for the e31 geometry, respectively. This study suggests the importance of the blending ratio and strain geometry for higher output-power generation in a piezoelectric nanocomposite-based nanogenerator. PACS 77.65.-j; 77.84.-s; 73.21.Hb PMID:24386884

2014-01-01

8

Large strain under a low electric field in lead-free bismuth-based piezoelectrics  

NASA Astrophysics Data System (ADS)

In this letter, the composition and electric field dependent strain behavior of (1 - x)Bi0.5(Na0.78K0.22)0.5TiO3-xBi(Mg0.5Ti0.5)O3 (BNKT-BMT) were investigated to develop lead-free piezoelectric materials with a large strain response at a low driving field for actuator applications. A large strain of 0.35% (Smax/Emax = 636 pm/V) at an applied field of 55 kV/cm was obtained with a composition of 4 mol. % BMT. In particular, the electric field required to deliver large strains was reduced to a level that revealed not only a large Smax/Emax of 542 pm/V at a driving field as low as 35 kV/cm, but also remarkably suppressed the large hysteresis.

Ullah, Aman; Won Ahn, Chang; Ullah, Amir; Won Kim, Ill

2013-07-01

9

Ferroelectric instabilities and enhanced piezoelectric response in Ce modified BaTiO3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

The crystal structure, ferroelectric, and piezoelectric behaviors of the Ba(Ti1-xCex)O3 solid solution have been investigated at close composition intervals in the dilute concentration regime. Ce concentration as low as 2 mol. % induces tetragonal-orthorhombic instability and coexistence of the phases, leading to enhanced high-field strain and direct piezoelectric response. Detailed structural analysis revealed tetragonal + orthorhombic phase coexistence for x = 0.02, orthorhombic for 0.03 ? x ? 0.05, and orthorhombic + rhombohedral for 0.06 ? x ? 0.08. The results suggest that Ce-modified BaTiO3 is a potential lead-free piezoelectric material.

Brajesh, Kumar; Kalyani, Ajay Kumar; Ranjan, Rajeev

2015-01-01

10

Dielectric and piezoelectric properties of lead-free (Bi,Na)TiO3-based thin films  

NASA Astrophysics Data System (ADS)

Dielectric and piezoelectric properties of morphotropic phase boundary (Bi,Na)TiO3-(Bi,K)TiO3-BaTiO3 epitaxial thin films deposited on SrRuO3 coated SrTiO3 substrates were reported. Thin films of 350 nm thickness exhibited small signal dielectric permittivity and loss tangent values of 750 and 0.15, respectively, at 1 kHz. Ferroelectric hysteresis measurements indicated a remanent polarization value of 30 ?C/cm2 with a coercive field of 85-100 kV/cm. The thin film transverse piezoelectric coefficient (e31,f) of these films after poling at 600 kV/cm was found to be -2.2 C/m2. The results indicate that these BNT-based thin films are a potential candidate for lead-free piezoelectric devices.

Abazari, M.; Safari, A.; Bharadwaja, S. S. N.; Trolier-McKinstry, S.

2010-02-01

11

Temperature Stability of V2O5-Doped KNN-LS-BF Lead-Free Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

V2O5-doped Na0.5K0.5NbO3-LiSbO3-BiFeO3 (KNN-LS-BF) lead-free piezoelectric ceramics were prepared by the traditional sintering method, and their temperature stability was studied. Characterization of the temperature dependences of dielectric and piezoelectric properties of the V2O5-doped KNN-LS-BF ceramics showed that V2O5 doping could significantly improve the temperature stability in the temperature range of 30°C to 420°C and cause a downward shift in the orthorhombic-tetragonal phase transition to below room temperature. It was also found that the V2O5-doped KNN-LS-BF ceramics possess good dielectric and piezoelectric properties ( ? r > 1066, tan ? < 4%, d 33 > 185 pC/N, k p > 0.25) in the temperature range of 30°C to 300°C.

Wang, Hua; Zhai, Xia; Xu, Ji-Wen; Yuan, Chang-Lai; Yang, Ling

2013-08-01

12

Growth and properties of Li, Ta modified (K,Na)NbO3 lead-free piezoelectric single crystals  

PubMed Central

Li, Ta modified (K,Na)NbO3 single crystals with the size of 18 mm × 18 mm × 10 mm were successfully grown by top-seeded solution growth method, with orthorhombic–tetragonal phase transition temperature ~79 °C and Curie temperature ~276 °C. The electromechanical coupling factors k33 and kt were found to be ~88% and ~65%, respectively. The piezoelectric coefficient d33 for the [001]c poled crystals reached 255 pC/N. In addition, the electromechanical coupling factor exhibited high stability over the temperature range of ?50 °C to 70 °C, making these lead free crystals good candidates for electromechanical applications. PMID:25404953

Huo, Xiaoqing; Zheng, Limei; Zhang, Shujun; Zhang, Rui; Liu, Gang; Wang, Rui; Yang, Bin; Cao, Wenwu; Shrout, Thomas R.

2014-01-01

13

Dielectric and Piezoelectric Properties of Bi0.5K0.5TiO3-BaNb2O6 Lead-Free Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric ceramics (1 - x)Bi0.5K0.5TiO3- xBaNb2O6 [(1 - x)KBT- xBN] with x ranging from 0 to 0.03 have been synthesized by a conventional solid-state reaction method. The effects of BaNb2O6 addition on the crystal structure, microstructure, and dielectric and piezoelectric properties of the Bi0.5K0.5TiO3 ceramic were investigated. In the studied composition range, the x-ray diffraction patterns revealed that single perovskite phase formed in specimens with x < 0.03 and a trace secondary phase could be detected for x = 0.03. A morphotropic phase boundary separating rhombohedral and tetragonal phases was identified in the range of x = 0.01 to 0.02, where the optimum dielectric and piezoelectric properties were achieved with values of dielectric constant ? = 2960, piezoelectric constant d 33 = 96 pC/N, electromechanical coupling factor k p = 17.8%, and mechanical quality factor Q m = 150. Dielectric study revealed that all samples showed diffuse phase-transition characteristics. Furthermore, polarization-electric field ( P- E) hysteresis loops were of slim-loop type with small remanent polarization values for all compositions. The related physical mechanisms for the enhancement of dielectric and piezoelectric properties are discussed. The results demonstrate a tremendous potential of the studied system for use as lead-free piezoelectric ceramics.

Pu, Yongping; Gao, Pan; Wu, Ting; Liu, Xiaoyan; Dong, Zijing

2015-01-01

14

Dielectric and Piezoelectric Properties of Bi0.5K0.5TiO3-BaNb2O6 Lead-Free Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric ceramics (1 - x)Bi0.5K0.5TiO3-xBaNb2O6 [(1 - x)KBT-xBN] with x ranging from 0 to 0.03 have been synthesized by a conventional solid-state reaction method. The effects of BaNb2O6 addition on the crystal structure, microstructure, and dielectric and piezoelectric properties of the Bi0.5K0.5TiO3 ceramic were investigated. In the studied composition range, the x-ray diffraction patterns revealed that single perovskite phase formed in specimens with x < 0.03 and a trace secondary phase could be detected for x = 0.03. A morphotropic phase boundary separating rhombohedral and tetragonal phases was identified in the range of x = 0.01 to 0.02, where the optimum dielectric and piezoelectric properties were achieved with values of dielectric constant ? = 2960, piezoelectric constant d 33 = 96 pC/N, electromechanical coupling factor k p = 17.8%, and mechanical quality factor Q m = 150. Dielectric study revealed that all samples showed diffuse phase-transition characteristics. Furthermore, polarization-electric field (P-E) hysteresis loops were of slim-loop type with small remanent polarization values for all compositions. The related physical mechanisms for the enhancement of dielectric and piezoelectric properties are discussed. The results demonstrate a tremendous potential of the studied system for use as lead-free piezoelectric ceramics.

Pu, Yongping; Gao, Pan; Wu, Ting; Liu, Xiaoyan; Dong, Zijing

2014-12-01

15

Piezoelectric Vibrational Energy Harvester Using Lead-Free Ferroelectric BiFeO3 Films  

NASA Astrophysics Data System (ADS)

We have proposed that BiFeO3 films are suitable for piezoelectric vibrational energy harvester (VEH) applications, because BiFeO3 has high spontaneous polarization and low dielectric permittivity. We demonstrated that energy can be harvested by a micromachined VEH using a BiFeO3 film deposited using a sol-gel process. A VEH with a resonant frequency of ˜98 Hz produced an output voltage of 1.5 V·G-1 and electrical power of 2.8 µW·mm-3·G-2 (G=9.8 m/s2) at a load resistance of 1 M?. Using the analytical model for VEH, the generalized electromechanical coupling factor was estimated to be 0.41%. These results were comparable to those of the best-performing VEHs using other piezoelectric films.

Yoshimura, Takeshi; Murakami, Shuichi; Wakazono, Keisuke; Kariya, Kento; Fujimura, Norifumi

2013-05-01

16

New potassium-sodium niobate material system: a giant-d?? and high-T(C) lead-free piezoelectric.  

PubMed

In this work, we elucidate the influence of Bi(0.5)Li(0.5)ZrO3 (BLZ) content on the phase structure, microstructure, and electrical properties of (1 -x)K(0.40)Na(0.60)Nb(0.965)Sb(0.035)O3-xBi(0.5)Li(0.5)ZrO3 lead-free ceramics. We simultaneously achieved a giant d33 and a high T(C) in this material system. The coexistence of rhombohedral and tetragonal phases is responsible for such a large d33 in the ceramics with BLZ contents (x) ranging from 0.025 to 0.035. Doping with BLZ not only induces the formation of the phase boundary, but also maintains a high T(C). The ceramic with x = 0.03 shows an enhanced piezoelectric behaviour (d33 ~ 400 pC N(-1) and k(p) ~ 0.47) together with a high T(C) of 292 °C. A good temperature stability for ferroelectricity and piezoelectricity is also observed in these ceramics. This study is the first time that such a good comprehensive performance has been obtained in potassium-sodium niobate materials. We believe that this type of material system possessing giant-d33 and high-T(C) is a promising candidate for use in high-temperature piezoelectric devices. PMID:24958201

Zheng, Ting; Wu, Jiagang; Cheng, Xiaojing; Wang, Xiaopeng; Zhang, Binyu; Xiao, Dingquan; Zhu, Jianguo; Lou, Xiaojie; Wang, Xiangjian

2014-08-14

17

Enhanced Piezoelectric Properties and Tunability of Lead-Free Ceramics Prepared by High-Energy Ball Milling  

NASA Astrophysics Data System (ADS)

Zirconium-doped barium titanate Ba(Zr0.15Ti0.85)O3 lead-free ceramics (hereinafter referred to as BZT) were synthesized using the solid-state reaction method by adopting the high-energy ball milling technique. Nanosized BZT powders resulted from high-energy ball milling, which in turn enhanced the dielectric and piezoelectric properties of the ceramics. A single-phase perovskite structure free from secondary phase peaks was observed for sintered BZT samples, and a relative density of ˜94% of the theoretical density was achieved. The electric-field-induced polarization-current data indicate the ferroelectric nature of the samples. Unipolar strain as high as 0.12% was realized for the ceramics sintered at 1350°C, indicating their potential for use in actuator applications. Very high tunability of >70% for these ceramics is also reported.

Mahesh, M. L. V.; Bhanuprasad, V. V.; James, A. R.

2013-12-01

18

Tailoring of unipolar strain in lead-free piezoelectrics using the ceramic/ceramic composite approach  

SciTech Connect

The electric-field-induced strain response mechanism in a polycrystalline ceramic/ceramic composite of relaxor and ferroelectric materials has been studied using in situ high-energy x-ray diffraction. The addition of ferroelectric phase material in the relaxor matrix has produced a system where a small volume fraction behaves independently of the bulk under an applied electric field. Inter- and intra-grain models of the strain mechanism in the composite material consistent with the diffraction data have been proposed. The results show that such ceramic/ceramic composite microstructure has the potential for tailoring properties of future piezoelectric materials over a wider range than is possible in uniform compositions.

Khansur, Neamul H.; Daniels, John E. [School of Materials Science and Engineering, University of New South Wales, NSW 2052 (Australia); Groh, Claudia; Jo, Wook; Webber, Kyle G. [Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Reinhard, Christina [Diamond Light Source, Beamline I12 JEEP, Didcot, Oxfordshire OX11 0DE (United Kingdom); Kimpton, Justin A. [The Australian Synchrotron, Clayton, Victoria 3168 (Australia)

2014-03-28

19

Strain engineering effects on electrical properties of lead-free piezoelectric thin films on Si wafers.  

PubMed

Using radio frequency - magnetron sputtering, calcium-doped barium zirconate titanate ((Ba(0.85)Ca(0.15))(Zr(0.1)Ti(0.9))O(3), BCZT) thin films were deposited on Si wafers with different bottom electrodes. The obtained BCZT thin film on a lanthanum nickel oxide (LNO) electrode had a highly c-axis preferred orientation, while the BCZT thin film on a Pt bottom electrode had (111) preferred orientation. Furthermore, the out-of-plane lattice constant of the BCZT on LNO/Si was 3.4% larger than that of the reported bulk material because of the compressive thermal stress from LNO with a large thermal expansion coefficient. This compressive thermal stress engenders an increase of the Curie temperature. The local piezoelectric response of the BCZT thin film on a LNO/Si structure was measured by piezoresponse force microscope. PMID:25286200

Ohno, Tomoya; Kamai, Yuto; Oda, Yuutaro; Sakamoto, Naonori; Matsuda, Takeshi; Wakiya, Naoki; Suzuki, Hisao

2014-01-01

20

(Bi(1\\/2)Na(1\\/2))TiO3-BaTiO3 system for lead-free piezoelectric ceramics  

Microsoft Academic Search

One of the (Bi(1\\/2)Na(1\\/2))TiO3 (BNT)-based solid solutions, Ba-modified bismuth sodium titanate, (Bi(1\\/2)Na(1\\/2))(1-x)Ba(x)TiO3 (BNBT), is studied for its dielectric and piezoelectric properties as a new group of lead-free piezoelectric ceramics. A rhombohedral (F sub alpha)-tetragonal (F sub beta) morphotropic phase boundary (MPB) is shown to exist at x = 0.06-0.07 by X-ray data, and dielectric and piezoelectric properties. BNBT ceramics with

Tadashi Takenaka; Kei-Ichi Maruyama; Koichiro Sakata

1991-01-01

21

Synthesis of (K, Na) (Nb, Ta)O 3 lead-free piezoelectric ceramic powders by high temperature mixing method under hydrothermal conditions  

Microsoft Academic Search

A facile hydrothermal route via high temperature mixing method was used to synthesize (K, Na) (Nb, Ta)O3 lead-free piezoelectric ceramic powders. The influence of Ta doping and K+\\/(K++Na+) molar ratios in the starting solution on the resultant powders were investigated by X-ray diffraction, scanning electron microscope, transmission electron microscopy, and selected area electron diffraction. The Ta element was successfully doped

Honghui Gu; Kongjun Zhu; Xuming Pang; Bin Shao; Jinhao Qiu; Hongli Ji

22

Enhanced ferroelectricity, piezoelectricity, and ferromagnetism in Nd-modified BiFeO3-BaTiO3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

Lead-free multiferroic ceramics of 0.75Bi1-xNdxFeO3 - 0.25BaTiO3 + 1 mol. % MnO2 were prepared by a conventional ceramic technique and their structure, piezoelectricity, and multiferroicity were studied. The ceramics sintered at 890-990 °C possess a pure perovskite structure. A morphotropic phase boundary of rhombohedral and monoclinic phases is formed at x = 0.05. A small amount of Nd improves the ferroelectric and piezoelectric properties of the ceramics. The ferroelectric-paraelectric phase transition becomes gradually diffusive with x increasing. After the addition of Nd, the ferromagnetism of the ceramics is greatly enhanced by ˜320%. The increase in sintering temperature improves significantly the ferroelectric, piezoelectric, and ferromagnetic properties of the ceramics. The ceramics with x = 0.05 sintered at 950-990 °C possess improved ferroelectricity, piezoelectricity, magnetism and insulation with Pr of 16.5-17.5 ?C/cm2, d33 of 113-121 pC/N, Mr of 0.127-0.138 emu/g, R of ˜5 × 109 ?.cm and high TC of 473-482 °C, indicating that the ceramic is a promising candidate for room-temperature multiferroic and high-temperature piezoelectric materials.

Zheng, Qiaoji; Luo, Lingling; Lam, Kwok Ho; Jiang, Na; Guo, Yongquan; Lin, Dunmin

2014-11-01

23

Dielectric and piezoelectric properties of (Bi 1? x ? y Nd x Na 1? y ) 0.5Ba y TiO 3 lead-free ceramics  

Microsoft Academic Search

New lead-free (Bi1?x?yNdxNa1?y)0.5BayTiO3 ceramics were prepared by a conventional ceramic technique and their dielectric and piezoelectric properties were studied. X-ray diffraction studies reveal that Nd3+ and Ba2+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a new solid solution with a pure perovskite structure, and a morphotropic phase boundary (MPB) of rhombohedral and tetragonal phases is formed at 0.04

Dunmin Lin; K. W. Kwok

2010-01-01

24

Dielectric and piezoelectric properties of sodium lithium niobate Na1-xLixNbO3 lead free ferroelectric ceramics  

E-print Network

ferroelectric ceramics G. R. Li & Q. R. Yin & L. Y. Zheng Y. Y. Guo & W. W. Cao Published online: 17 May 2007 curves of LNN ceramics showed that there exist three phase transitions from room temperature up. The solid solution NaxLi1-xNbO3 (LNN) ceramics is a very interest- ing material due to its lead free

Cao, Wenwu

25

Effect of poling temperature on piezoelectricity of CaZrO3-modified (K, Na)NbO3-based lead-free ceramics  

NASA Astrophysics Data System (ADS)

Electrical poling is indispensable for endowing isotropic ferroelectric polycrystals with a net macroscopic polarization and hence piezoelectricity. However, little attention has been paid to the optimization of poling conditions in (K, Na)NbO3-based ceramics with a polymorphic phase transition. This study investigated the electrical properties of CaZrO3-modified (K, Na, Li)(Nb, Ta)O3 lead-free piezoceramics as a function of the poling temperature. Peak piezoelectric coefficient d33 of 352 ± 7 pC/N and planar electromechanical coupling factor kp of 0.47 were obtained at the optimized poling temperature of 120 °C, which crosses the polymorphic phase transition regime. In-depth analysis of the asymmetric polarization hysteresis loops and bipolar strain curves uncovered striking analogy between electrical poling and unipolar cycling in the current system, which is attributed to a competition between domain reorientation and space charge accumulation.

Yao, Fang-Zhou; Wang, Ke; Jo, Wook; Lee, Jae-Shin; Li, Jing-Feng

2014-09-01

26

Ferroelectric and impedance response of lead-free (B0.5N0.5) TiO3-BaZrO3 piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric (0.96B0.5N0.5TiO3)-0.04BaZrO3 (BNT-BZ4) was synthesized by using a solid-state reaction method. SEM micrograph shows dense microstructure. X-ray diffraction (XRD) indicated the formation of a BNB-BZ4 single phase having pseudocubic symmetry. A maximum value of remnant polarization (30?C/cm2) and piezoelectric constant (112 pC/N) was observed for BNT-BZ4 ceramic. The temperature dependences of the dielectric properties of BNT-BZ4 were investigated in the temperature range of 25-600°C at various frequencies (0.1 Hz-1 MHz). The maximum dielectric constant value (epsilonr) reaches a highest value of 4046 (at 10 kHz). The electrical properties were investigated by using complex impedance spectroscopy and provided better understanding of relaxation process.

Rahman, Jamil ur; Hussain, Ali; Maqbool, Adnan; Kim, Jin Soo; Song, Tae Kwon; Lee, Je Hyun; Kim, Won Jeong; Kim, Myong Ho

2014-06-01

27

Morphotropic phase boundary and electric properties in (1-x)Bi0.5Na0.5TiO3-xBiCoO3 lead-free piezoelectric ceramics  

E-print Network

-free piezoelectric ceramics Fei-Fei Guo, Bin Yang, Shan-Tao Zhang, Xiao Liu, Li-Mei Zheng et al. Citation: J. Appl ceramics Appl. Phys. Lett. 101, 252905 (2012) Enhanced piezoelectric performance from carbon fluoropolymer phase boundary and electric properties in (12x)Bi0.5Na0.5TiO3-xBiCoO3 lead-free piezoelectric ceramics

Cao, Wenwu

28

Polymorphic structure evolution and large piezoelectric response of lead-free (Ba,Ca)(Zr,Ti)O{sub 3} ceramics  

SciTech Connect

The polymorphic structure evolution of (Ba,Ca)(Zr,Ti)O{sub 3} piezoelectric ceramics was investigated by analysis of the in situ X-ray diffraction and dielectric spectra. The results indicated that a confined orthorhombic (O) phase region induced by the approach of the rhombohedral (R) and tetragonal (T) phases existed in an extremely narrow temperature range of (Ba{sub 0.85}Ca{sub 0.15})(Zr{sub 0.1}Ti{sub 0.9})O{sub 3} composition. The electric properties near the O–T phase boundaries of (Ba{sub 0.95}Ca{sub 0.05})(Zr{sub 0.05}Ti{sub 0.95})O{sub 3} and (Ba{sub 0.85}Ca{sub 0.15})(Zr{sub 0.1}Ti{sub 0.9})O{sub 3} were compared. The results suggested that the confined O phase region is an important factor that contributes to the extremely large piezoelectric response.

Tian, Ye [Key Laboratory for Macromolecular Science of Shaanxi Province, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an 710062, Shaanxi (China); Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, Shaanxi (China); Chao, Xiaolian, E-mail: chaoxl@snnu.edu.cn, E-mail: yangzp@snnu.edu.cn; Wei, Lingling; Liang, Pengfei; Yang, Zupei, E-mail: chaoxl@snnu.edu.cn, E-mail: yangzp@snnu.edu.cn [Key Laboratory for Macromolecular Science of Shaanxi Province, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an 710062, Shaanxi (China); Jin, Li [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, Shaanxi (China)

2014-03-17

29

Large Piezoelectric Constant and High Curie Temperature of Lead-Free Piezoelectric Ceramic Ternary System Based on Bismuth Sodium Titanate-Bismuth Potassium Titanate-Barium Titanate near the Morphotropic Phase Boundary  

Microsoft Academic Search

A lead-free piezoelectric ceramic ternary system based on bismuth sodium titanate, (Bi1\\/2Na1\\/2)TiO3 (BNT) - bismuth potassium titanate (Bi1\\/2K1\\/2)TiO3 (BKT) - barium titanate BaTiO3 (BT) near the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral phases has been investigated. In the case of a(Bi1\\/2Na1\\/2)TiO3-bBaTiO3-c(Bi1\\/2K1\\/2)TiO3 [BNBK(100a\\/100b\\/100c)] solid solution ceramics, the highest piezoelectric constant d33=191 pC\\/N, Curie temperature, Tc=301°C, electromechanical coupling factor,

Hajime Nagata; Masaki Yoshida; Yoichi Makiuchi; Tadashi Takenaka

2003-01-01

30

Enhanced piezoelectricity and nature of electric-field induced structural phase transformation in textured lead-free piezoelectric Na0.5Bi0.5TiO3-BaTiO3 ceramics  

NASA Astrophysics Data System (ADS)

This letter provides a comparative description of the properties of textured and randomly oriented poly-crystalline lead-free piezoelectric 0.93(Na0.5Bi0.5TiO3)-0.07BaTiO3 (NBT-BT) ceramics. A high longitudinal piezoelectric constant of (d33) ˜ 322 pC/N was obtained in (001)PC textured NBT-7BT ceramics, which is almost ˜2× times the d33 coefficient reported for randomly oriented ceramics of the same composition. In situ neutron diffraction experiments revealed that characteristically different structural responses are induced in textured and randomly oriented NBT-BT ceramics upon application of electric fields (E), which are likely related to the varying coherence lengths of polar nanoregions and internal stresses induced by domain switching.

Maurya, Deepam; Pramanick, Abhijit; An, Ke; Priya, Shashank

2012-04-01

31

Piezoelectric piggy-back microactuator for hard disk drive  

Microsoft Academic Search

A new piezoelectric piggy-back microactuator for high density hard disk drives was designed and fabricated to achieve more accurate positioning of the magnetic head and increasing servo bandwidth. The microactuator is made of stiff piezoelectric ceramic material to actuate the slider on which the head-element is formed. It is designed to amplify the actuating displacement. The basic mechanical performance of

Yoshikazu Soeno; Sliinji Ichikawa; Takamitsu Tsuna; Yoshikazu Sato; Isamu Sato

1999-01-01

32

Fabrication of Lead-Free Lithium-Doped Na0.5K0.5NbO3 Piezoelectric Ceramics with Dense Grain Structure Using Sol-Gel Surface Coating  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric 0.06(LiNbO3)-0.94(Na0.5K0.5)NbO3 (LNKN) ceramics in disc form were fabricated and characterized to acquire good electromechanical properties. A molding method including cold isostatic pressing (CIP) was used to form a dense and regular microstructure and suppress the cracking problems of LNKN ceramics during the following high-temperature sintering. The LNKN ceramic sintered at 1040 °C showed a high piezoelectric constant d33 of 170 pC/N owing to its high density. Furthermore, perovskite LNKN films with the same composition as the ceramics were fabricated using 2-methoxyethanol-based sol-gel solution. The sol-gel surface coating on the LNKN ceramics was found to be very effective for increasing the piezoelectric constant because of the interface stabilization effect leading to a uniform electric field in piezoelectric elements. As a result, we obtained the highest piezoelectric constant d33 of 183 pC/N. The lead-free LNKN ceramics are promising for applications in eco-friendly ferroelectric and piezoelectric devices.

Lim, Sun Kyung; Han, Jeong Seon; Yoo, Ae Ri; Lee, Seong Eui; Lee, Hee Chul

2013-10-01

33

Phase transition temperatures and piezoelectric properties of (Bi(1/2)Na(1/2))TiO3- and (Bi(1/2)K(1/2))TiO3-based bismuth perovskite lead-free ferroelectric ceramics.  

PubMed

The phase transition temperatures and the dielectric, ferroelectric, and piezoelectric properties of bismuth perovskite lead-free ferroelectric ceramics such as (Bi(1/2)Na(1/2))TiO3 (BNT)- and (Bi(1/2)Na(1/2))TiO3 (BKT)-based solid solutions have been reviewed. According to the results obtained by our group, these ceramics can be considered as superior lead-free piezoelectric materials for reducing environmental damage. Perovskite-type ceramics appear to be suitable for actuator and high-power applications that require a large piezoelectric constant d33 and a high Curie temperature TC or a high depolarization temperature Td (> 200 degrees C). In this paper, we summarize the relationship between phase transition temperatures and piezoelectric properties. In the case of the BNT-based solid solutions, the highest piezoelectric properties were obtained at the morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases. However, d33 and Td were shown to have a tradeoff relationship. Considering the high Td and high d33, the tetragonal side of the MPB composition is suitable for piezoelectric actuator application. Meanwhile, the Qm values on the rhombohedral side of the MPB composition were better than those on the tetragonal side, and excellent high-power characteristics were obtained for Mn-doped BNT-(Bi(1/2)Na(1/2))TiO3-BKT ternary systems with rhombohedral symmetry. BKT ceramics were prepared by the hot-pressing (HP) method, and their ferroelectric and piezoelectric properties were clarified. BKT ceramics doped with a small amount of Bi have a relatively high remanent polarization of Pr = 27.6 microC/cm2 and high piezoelectric properties (k33 = 0.40 and d33 = 101 pC/N). In addition, it was clarified that BKT ceramics have a high Td of approximately 300 degrees C. The solid solution (1-x)BKT-xBaTiO3 (BKT-BT100x) exhibited a high Td of approximately 300 degrees C at x > 0.4. PMID:19686975

Takenaka, Tadashi; Nagata, Hajime; Hiruma, Yuji

2009-08-01

34

Determination of crystallographic orientation of lead-free piezoelectric (K,Na)NbO{sub 3} epitaxial thin films grown on SrTiO{sub 3} (100) surfaces  

SciTech Connect

Crystallographic structure of sol-gel-processed lead-free (K,Na)NbO{sub 3} (KNN) epitaxial films on [100]-cut SrTiO{sub 3} single-crystalline substrates was investigated for a deeper understanding of its piezoelectric response. Lattice parameter measurement by high-resolution X-ray diffraction and transmission electron microscopy revealed that the orthorhombic KNN films on SrTiO{sub 3} (100) surfaces are [010] oriented (b-axis-oriented) rather than commonly identified c-axis orientation. Based on the crystallographic orientation and corresponding ferroelectric domain structure investigated by piezoresponse force microscopy, the superior piezoelectric property along b-axis of epitaxial KNN films than other orientations can be explained.

Yu, Qi; Zhu, Fang-Yuan; Cheng, Li-Qian; Wang, Ke; Li, Jing-Feng, E-mail: jingfeng@mail.tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084 Beijing (China)] [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084 Beijing (China)

2014-03-10

35

Phase transition behavior and high piezoelectric properties in lead-free BaTiO3CaTiO3BaHfO3 ceramics  

E-print Network

ceramics Dali Wang · Zhaohua Jiang · Bin Yang · Shantao Zhang · Mingfu Zhang · Feifei Guo · Wenwu Cao of lead-free (1-x)Ba(Hf0.16Ti0.84)O3­x (Ba0.70Ca0.30)TiO3 (BCHT) ceramics fabricated by the conventional been proposed based on their dielectric behavior. It is found that BHCT ceramics undergo a complicated

Cao, Wenwu

36

First principles study of lead free piezoelectric AgNbO3 and (Ag1-xKx)NbO3 solid solutions  

NASA Astrophysics Data System (ADS)

We present an ab-initio study of structural, electronic and ferroic properties of lead-free orthorhombic AgNbO3 in centrosymmetric Pbcm and recently proposed noncentrosymmetric Pmc21 space group symmetries. The calculated polarization of AgNbO3 in Pmc21 phase is ˜0.09 ?C/cm2, whereas it is 55.9 ?C/cm2 in the ideal cubic phase. The large polarization of AgNbO3 in the ideal cubic structure is attributed to off-centering of Ag as well as Nb ions at the A and B sites, respectively. In our calculations both phases (Pmc21 and Pbcm) of AgNbO3 show small relative energy difference (˜0.1 meV/f.u), thus suggesting the coexistence of centrosymmetric and non-centrosymmetric phases and thereby antiferroelectric and ferroelctric order in room temperature AgNbO3 polycrystals. We further study structural properties and spontaneous polarization in orthorhombic Pmc21 Ag1-xKxNbO3 solid solutions. The calculated spontaneous polarization of AgNbO3 is enhanced due to suppression of NbO6 octahedral tilt angles as K ion is substituted at Ag sites. Our study suggests that appropriate cation substitution should indeed result in the improvement of ferroelectric properties of lead-free AgNbO3.

Niranjan, Manish K.; Asthana, Saket

2012-09-01

37

Investigation of a new lead-free Bi0.5(Na0.40K0.10)TiO3-(Ba0.7Sr0.3)TiO3 piezoelectric ceramic  

PubMed Central

Lead-free piezoelectric compositions of the (1-x)Bi0.5(Na0.40K0.10)TiO3-x(Ba0.7Sr0.3)TiO3 system (when x = 0, 0.05, 0.10, 0.15, and 0.20) were fabricated using a solid-state mixed oxide method and sintered between 1,050°C and 1,175°C for 2 h. The effect of (Ba0.7Sr0.3)TiO3 [BST] content on phase, microstructure, and electrical properties was investigated. The optimum sintering temperature was 1,125°C at which all compositions had densities of at least 98% of their theoretical values. X-ray diffraction patterns that showed tetragonality were increased with the increasing BST. Scanning electron micrographs showed a slight reduction of grain size when BST was added. The addition of BST was also found to improve the dielectric and piezoelectric properties of the BNKT ceramic. A large room-temperature dielectric constant, ?r (1,609), and piezoelectric coefficient, d33 (214 pC/N), were obtained at an optimal composition of x = 0.10. PMID:22221833

2012-01-01

38

Piezoelectric and ferroelectric properties of (Bi0.94-xLaxNa0.94)0.5Ba0.06TiO3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric ceramics (Bi0.94-x LaxNa0.94)0.5Ba0.06TiO3 have been fabricated by an ordinary sintering technique, and their piezoelectric and ferroelectric properties have been studied. The results of x-ray diffraction reveal that La3+ and Ba2+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a new solid solution with a pure perovskite structure. After the partial substitution of La3+ for Bi3+ in the (Bi0.94-x Lax Na0.94)0.5Ba0.06TiO3 ceramics (x = 0-0.04), the ceramics exhibit a lower coercive field Ec and a larger remanent polarization Pr. Because of the large Pr and low Ec, the ceramics with x = 0.02-0.04 exhibit optimum piezoelectric properties: d33 = 181-196 pC N-1 and kP = 33.2-36.3%. The depolarization temperature Td decreases with increasing x (x = 0 - 0.04). At the high La3+ level (x = 0.06-0.12), the ceramics exhibit weak ferroelectricity and thus possess very poor piezoelectricity, and the low dielectric anomaly at Td disappears. In addition, the ceramics exhibit a relaxor characteristic, which probably results from the cation disordering in the 12-fold coordination sites. The temperature dependences of the ferroelectric and dielectric properties suggest that the ceramics with x = 0-0.04 may contain both polar and non-polar regions at temperatures above Td, while for the ceramics with x = 0.06-12, the polar and non-polar regions coexist at room temperature.

Zheng, Qiaoji; Xu, Chenggang; Lin, Dunmin; Gao, Daojiang; Kwok, K. W.

2008-06-01

39

Ferroelectric and piezoelectric properties of [(Bi 0.98 La 0.02 Na 1? x Li x ) 0.5 ] 0.94 Ba 0.06 TiO 3 lead-free ceramics  

Microsoft Academic Search

Lead-free ceramics [(Bi0.98La0.02Na1?x\\u000a Li\\u000a x\\u000a )0.5]0.94Ba0.06TiO3 have been prepared by an ordinary sintering technique and their ferroelectric and piezoelectric properties have been studied.\\u000a The results of X-ray diffraction reveal that Li+, Ba2+, and La3+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a new solid solution with a pure perovskite structure. The partial substitution of Li+ lowers the coercive field E

Dunmin Lin; K. W. Kwok

2009-01-01

40

Lead-free piezoelectric (K0.5Na0.5)NbO3 thin films derived from chemical solution modified with stabilizing agents  

NASA Astrophysics Data System (ADS)

(K0.5Na0.5)NbO3 (KNN)-based ferroelectric thin films were prepared by a chemical solution approach modified with both diethanolamine (DEA) and ethylenediaminetetraacetic acid (EDTA) as the stabilizing agents. The obtained KNN thin films exhibited a remarkably low leakage current and well-saturated polarization hysteresis loop. The effective piezoelectric strain coefficient d33 and voltage coefficient g33 under the clamping of the substrate were improved to 74.0 pm/V and 28.3 mm V/N, respectively. The reason for the superior properties was found that the addition of EDTA and DEA was effective in suppressing the volatilization of K and Na at moderate temperature before the crystallization.

Goh, Phoi Chin; Yao, Kui; Chen, Zhong

2010-09-01

41

Origin of high piezoelectric response in A-site disordered morphotropic phase boundary composition of lead-free piezoelectric 0.93(Na0.5Bi0.5)TiO3-0.07BaTiO3  

NASA Astrophysics Data System (ADS)

Perovskite piezoelectric compositions near the morphotropic phase boundary (MPB) are known to exhibit high piezoelectric response. In lead-based ABO3 compound with B-site disorder, the origin of this enhancement has been associated with the presence of an intermediate monoclinic/orthorhombic state that bridges the adjacent ferroelectric rhombohedral and tetragonal phases. However, the origin of high piezoelectric response in lead-free ABO3 compounds with A-site disorder has not been conclusively established. We describe a microscopic model derived from comparative analyses of high resolution transmission electron microscopy and neutron diffraction that explains the origin of high piezoelectric response in lead-free MPB compositions of 0.93(Na0.5Bi0.5)TiO3-0.07BaTiO3. Direct observation of nanotwins with monoclinic symmetry confirmed the presence of an intermediate bridging phase that facilitates a pathway for polarization reorientation. Monoclinic distortions of an average rhombohedral phase are attributed to localized displacements of atoms along the non-polar directions.

Maurya, Deepam; Murayama, M.; Pramanick, A.; Reynolds, W. T.; An, Ke; Priya, Shashank

2013-03-01

42

Diffuse phase transition and electrical properties of lead-free piezoelectric (LixNa1-x)NbO3 (0.04 ? x ? 0.20) ceramics near morphotropic phase boundary  

NASA Astrophysics Data System (ADS)

Temperature-dependent dielectric permittivity of lead-free (LixNa1-x)NbO3 for nominal x = 0.04-0.20, prepared by solid state reaction followed by sintering, was studied to resolve often debated issue pertaining to exactness of morphotropic phase boundary (MPB) location besides structural aspects and phase stability in the system near MPB. Interestingly, a diffuse phase transition has been observed in the dielectric permittivity peak arising from the disorder induced in A-site and structural frustration in the perovskite cell due to Li substitution. A partial phase diagram has been proposed based on temperature-dependent dielectric permittivity studies. The room temperature piezoelectric and ferroelectric properties were investigated and the ceramics with x = 0.12 showed relatively good electrical properties (d33 = 28 pC/N, kp = 13.8%, Qm = 440, Pr = 12.5 ?C/cm2, Ec = 43.2 kV/cm, and Tm = 340 °C). These parameter values make this material suitable for piezoelectric resonator and filter applications. Moreover, a high dielectric permittivity (?'r = 2703) with broad diffuse peak near transition temperature, and low dielectric loss (<4%) over a wide temperature range (50-250 °C) found in this material may also have a potential application in high-temperature multilayer capacitors in automotive and aerospace related industries.

Mitra, S.; Kulkarni, A. R.; Prakash, Om

2013-08-01

43

Growth and characterization of lead-free piezoelectric BaZr0.2Ti0.8O3-Ba0.7Ca0.3TiO3 thin films on Si substrates  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric BaZr0.2Ti0.8O3-Ba0.7Ca0.3TiO3 (BCZT) thin films were grown on La0.7Sr0.3MnO3-buffered Si (0 0 1) by off-axis RF magnetron sputtering at temperatures ranging from 550 to 810 °C. In this article, we present the detailed investigation on structure, leakage current behaviors and electromechanical properties of BCZT thin films. The crystallographic texture and grain size of the as-grown thin films are strongly dependent on the growth temperature, which consequently affects the leakage behaviors and local electromechanical properties. The crystallographic orientation becomes better and the grain size increases when increased the substrate temperature. The dominant leakage mechanism is found to be space-charge-limited conduction at low electric field, while a Fowler-Nordheim tunneling is confirmed in high electric field region for the films deposited at 710 °C and 810 °C. The increasing growth temperature also leads to remarkable improvement in the local electromechanical properties of the films. The BCZT film deposited at an optimal temperature of 810 °C exhibits a considerably high effective piezoelectric coefficient d33,f of 94 ± 4 pm/V, which is comparable to that of a typical lead zirconate titanate thin film.

Luo, B. C.; Wang, D. Y.; Duan, M. M.; Li, S.

2013-04-01

44

Structure, ferroelectric and piezoelectric properties of (Bi0.98- x La0.02Na1- x )0.5Ba x TiO3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

Lead-free (Bi0.98- x La0.02Na1- x )0.5Ba x TiO3 ceramics have been prepared by an ordinary sintering technique and their structure, ferroelectric and piezoelectric properties have been studied. The results of X-ray diffraction show that La2+ and Ba2+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a new solid solution with a pure perovskite structure, and a morphotropic phase boundary (MPB) exists at 0.04< x<0.10. Compared with pure Bi0.5Na0.5TiO3 ceramics, the (Bi0.98- x La0.02Na1- x )0.5Ba x TiO3 ceramics possess much smaller coercive field E c and larger remanent polarization P r. Because of the low E c (3.38 kV/mm), large P r (46.2 ?C/cm2) and the formation of the MPB of rhombohedral and tetragonal phases, the piezoelectric properties of the ceramics are significantly enhanced at x=0.06: d 33=181 pC/N and k p=36.3%. The depolarization temperature T d reaches a minimum value near the MPB. The ceramics exhibit relaxor characteristic, which is probably a result from the cation disordering in the 12-fold coordination sites. The temperature dependences of the ferroelectric and dielectric properties suggest that the ceramics may contain both polar and non-polar regions at the temperatures above T d.

Lin, Dunmin; Kwok, K. W.

2009-10-01

45

Structure and electrical properties of (Bi0.5Na0.5)1-x-y-z BaxSryCazTiO3 lead-free piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

Lead-free (Bi0.5Na0.5)1-x-y-xBax SryCazTiO3 piezoelectric ceramics have been prepared by a conventional mixed oxide method, and their structural and electrical properties have been studied. The results of x-ray diffraction reveal that Ba2+, Sr2+ and Ca2+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a single-phase perovskite structure, and a morphotropic phase boundary (MPB) exists at x = 0.04-0.08, y = 0.015, z = 0.01. After the substitutions of Ba2+, Sr2+ and Ca2+, the ceramics exhibit a lower coercive field Ec and a larger remanent polarization Pr, which facilitates the poling and leads to an improvement in the piezoelectric coefficient d33 and the planar electromechanical coupling factor kP. Also, the depolarization temperature Td decreases, showing a strong dependence on the substitution level of Ba2+. For the ceramics with the compositions near the MPB, Pr = 44 µC cm-2, d33 = 173 pC N-1, kP = 34% and Td = 120 °C. In addition, the ceramics exhibit a relaxor characteristic, which probably results from the cation disordering in the 12-fold coordination sites. The results of the ferroelectric and dielectric properties at high temperatures suggest that the ceramics may contain both the polar and non-polar regions at temperatures above Td.

Lin, Dunmin; Kwok, K. W.; Chan, H. W. L.

2007-09-01

46

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives  

Microsoft Academic Search

A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d31 piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the

Yang Jing; Jianbin Luo; Wenyan Yang; Guoxian Ju

2004-01-01

47

Reliability Evaluation of Piezoelectric Micro-Actuators With Application in Hard Disk Drives  

Microsoft Academic Search

Piezoelectric micro-actuators have been extensively studied and used in hard disk drive head positioning systems. In these cases, piezoelectric micro-actuators\\/sensors experience high frequency cyclic loading during their operations. The fatigue failure and the lifespan of such micro-actuators become a concern of researchers and engineers. However, the probability and statistics based reliability theory has not been well developed for piezoelectric micro

Zhimin He; Han Tong Loh; Eng Hong Ong

2008-01-01

48

Raman- and Brillouin-scattering studies on lead-free piezoelectric Bi0.5(Na0.78K0.22)0.5- x TiO3 ceramics with A-site vacancies  

NASA Astrophysics Data System (ADS)

The Raman and Brillouin spectra of lead-free piezoelectric Bi0.5(Na0.78K0.22)0.5- x TiO3 ceramics with A-site vacancies were investigated for x = 0 ˜ 0.05. The Raman spectra measured at room temperature showed seven broad bands over the range of 50-1000 cm-1, reflecting strong anharmonicity, inherent A-site disorder and the resulting breakdown of the Raman selection rule. The splitting of the A1 mode near 270 cm-1 indicated that the tetragonal symmetry was maintained over the whole x range, consistent with the X-ray diffraction results. The Brillouin spectra exhibited distributed longitudinal and transverse acoustic modes, in addition to central peaks. The distributed acoustic modes were attributed to the scattering events at all scattering angles from 0 to 180° due to multiple reflections and refractions at the grain boundaries. The relaxation time obtained from fitting the broad central peak by using a Debye function exhibited a slowing-down behavior in the paraelectric phase. The formation of the central peak was attributed to the existence of nano-sized polar regions due to the anharmonic vibrations and the hopping motions of the A-site cations.

Kim, Tae Hyun; Kojima, Seiji; Ahn, Chang Won; Kim, Ill Won; Ko, Jae-Hyeon

2013-04-01

49

Structure, electrical properties and depolarization temperature of (Bi 0.5Na 0.5)TiO 3-BaTiO 3 lead-free piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

Lead-free ceramics (1 - x)Bi 0.5Na 0.5TiO 3- xBaTiO 3 have been prepared by a conventional solid reaction method, and their structure, electrical properties and depolarization temperature have been studied. The results of X-ray diffraction reveal that Ba 2+ diffuse into the Bi 0.5Na 0.5TiO 3 lattices to form a solid solution with a pure perovskite structure, and a morphotropic phase boundary (MPB) exists at 0.06 < x < 0.10. The grain size decreases with x. After the introduction of BaTiO 3 into Bi 0.5Na 0.5TiO 3, the ceramics exhibit a lower coercive field Ec and a larger remanent polarization Pr. Because of the strong ferroelectricity and MPB, the ceramics with x = 0.06 exhibit optimum piezoelectric properties: d33 = 155 pC/N and kP = 36.7%. The depolarization temperature Td shows a strong compositional dependence and gives a minimum value at MPB. In addition, the ceramics exhibit relaxor characteristic, which probably results from the cation disordering in the 12-fold coordination sites. The results of the ferroelectric and dielectric properties at high temperatures may suggest that the ceramics may contain both the polar and non-polar regions at temperatures above Td.

Xu, Chenggang; Lin, Dunmin; Kwok, K. W.

2008-07-01

50

A new Bi{sub 0.5}Na{sub 0.5}TiO{sub 3} based lead-free piezoelectric system with calculated end-member Bi(Zn{sub 0.5}Hf{sub 0.5})O{sub 3}  

SciTech Connect

The phase structure, dielectric and piezoelectric properties of a new lead-free piezoelectric system (1???x)Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}–xBi(Zn{sub 0.5}Hf{sub 0.5})O{sub 3} [(1???x)BNT–xBZH, x?=?0, 0.01, 0.02, 0.03, and 0.04] were investigated. The structure of Bi(Zn{sub 0.5}Hf{sub 0.5})O{sub 3} was calculated using first-principles method and (1???x)BNT–xBZH ceramics were fabricated by conventional solid-state process. At room temperature, a morphotropic phase boundary (MPB) from rhombohedral to pseudocubic is identified near x?=?0.02 by the analysis of X-ray diffraction patterns. The ceramics with MPB near room temperature exhibit excellent electrical properties: the Curie temperature, maximum polarization, remnant polarization, and coercive field are 340?°C, 56.3??C/cm{sup 2}, 43.5??C/cm{sup 2}, and 5.4?kV/mm, respectively, while the maximum positive bipolar strain and piezoelectric coefficient are 0.09% and 92 pC/N, respectively. In addition, a linear relationship between the MPB phase boundary composition and the calculated tetragonality of non-BNT end-member was demonstrated. Thus, this study not only shows a new BNT-based lead-free piezoelectric system but also suggest a new way to predict the composition at MPB a priori when designing new lead-free piezoelectric system.

Liu, Feng [The Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wahyudi, Olivia; Li, Yongxiang, E-mail: yxli@mail.sic.ac.cn [The Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

2014-03-21

51

New lead-free piezoelectric ceramics based on (K0.48Na0.52)(Nb0.95Ta0.05)O3-Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3.  

PubMed

(1 - x)(K0.48Na0.52)(Nb0.95Ta0.05)O3-xBi0.5(Na0.7K0.2Li0.1)0.5ZrO3 lead-free piezoelectric ceramics with a new type of phase boundary have been designed and fabricated. This phase boundary lies in the compositional range of 0.04 ? x ? 0.05, and is formed by the coexistence of the rhombohedral, orthorhombic, and tetragonal phases. Interestingly, we found that the ferroelectric, dielectric, and piezoelectric properties of the ceramics with compositions near the phase boundary are significantly enhanced. In particular, the ceramic with x = 0.045 shows the best piezoelectric behavior of d33 ? 290 pC/N and kp ? 0.42 among all the compositions studied in this work, and it also exhibits a good thermal stability at annealing temperatures of ?270 °C. All these results indicate that such a material system is a good candidate for lead-free piezoelectric applications in the future. PMID:24452129

Cheng, Xiaojing; Wu, Jiagang; Wang, Xiaopeng; Zhang, Binyu; Zhu, Jianguo; Xiao, Dingquan; Wang, Xiangjian; Lou, Xiaojie

2014-03-01

52

Effect of ZnO-B2O3 addition on the dielectric and the piezoelectric properties of lead-free (Na0.525K0.443Li0.037)(Nb0.883Sb0.08Ta0.037)O3 ceramics  

NASA Astrophysics Data System (ADS)

(Na0.525K0.443Li0.037)(Nb0.883Sb0.08Ta0.037)O3 + x wt% ZnO-B2O3 (NKLNST + x ZnO-B2O3) lead-free piezoelectric ceramics were prepared via a conventional solid-state reaction for various values of x = {0, 0.3, 0.6, 0.9, 1.2}; then, the dielectric and the piezoelectric properties of these ceramics were investigated. A pure perovskite structure and a small secondary phase were observed in the X-ray diffraction patterns. For the 0.3-wt% ZnO-B2O3 specimen, a density of ? = 4.537 g/cm3, an electromechanical coupling factor of k P = 0.432, a mechanical quality factor of Q m = 96, and piezoelectric constant of d 33 = 209 pC/N were found to be optimal. These results indicate that the material with this composition is a promising candidate for use in a lead-free piezoelectric device.

Kim, You-Seok; Yoo, Ju-Hyun

2014-12-01

53

Effect of composition on electrical properties of lead-free Bi{sub 0.5}(Na{sub 0.80}K{sub 0.20}){sub 0.5}TiO{sub 3}-(Ba{sub 0.98}Nd{sub 0.02})TiO{sub 3} piezoelectric ceramics  

SciTech Connect

Lead-free piezoelectric ceramics with the composition of (1-x)Bi{sub 0.5}(Na{sub 0.80}K{sub 0.20}){sub 0.5}TiO{sub 3}-x(Ba{sub 0.98}Nd{sub 0.02})TiO{sub 3} or (1-x) BNKT-xBNdT (with x = 0-0.20 mol fraction) have been synthesized by a conventional mixed-oxide method. The compositional dependence of phase structure and electrical properties of the ceramics were systemically studied. The optimum sintering temperature of all BNKT-BNdT ceramics was found to be 1125 Degree-Sign C. X-ray diffraction pattern suggested that BNdT effectively diffused into BNKT lattice during sintering to form a solid solution with a perovskite structure. Scanning electron micrographs showed a slight reduction of grain size when BNdT was added. It was found that BNKT-0.10BNdT ceramic exhibited optimum electrical properties ({epsilon}{sub r} = 1716, tan{delta} = 0.0701, T{sub c} = 327 Degree-Sign C, and d{sub 33} = 211 pC/N), suggesting that this composition has a potential to be one of a promising lead-free piezoelectric candidate for dielectric and piezoelectric applications.

Jaita, Pharatree [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Watcharapasorn, Anucha; Jiansirisomboon, Sukanda [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2013-07-14

54

A study of microstructural development, hardness and micro-creep of Sn-3.5Ag-0.7Cu lead-free solder alloy prepared by rapid solidification  

NASA Astrophysics Data System (ADS)

The Sn-3.5Ag-0.7Cu lead-free solder alloy has been prepared by normal casting and melt-spinning techniques to investigate the microstructural development, hardness and micro-creep of this alloy due to rapid solidification. The microstructure of the rapidly solidified ribbons and ingot samples has been investigated by SEM and X-ray diffraction (XRD) techniques. The results showed that the structure of the alloy prepared by normal casting is composed of Cu-Sn and Ag-Sn IMCs finely dispersed in Sn matrix, while these fine dispersions are not present in the rapidly solidified sample indicating that the rapid solidification rate is high enough to retain most of the Ag and Cu elements in nonequilibrium supersaturated solid solutions of ?-Sn. Additionally, the mechanical properties of both slowly and rapidly cooled samples are examined by using Vickers microhardness tester at different loads in the range of them 0.098 to 4.9 N. The hardness value of the rapidly cooled sample was found to be 1.3 times higher than that of the slowly cooled sample due to refinement of the rapidly cooled sample as well as the nonequilibrium solid solutions of Ag and Cu in the ?-Sn matrix. Besides, indentation creep behavior of both slowly and rapidly cooled samples is examined by using Vickers microhardness tester for three different values of the applied loads.

Gouda, El Said

2011-09-01

55

High electrostrictive coefficient Q33 in lead-free Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

In this study, the electrostrictive effect in Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 (BZT-xBCT, x = 0.4, 0.5, and 0.6) ceramics was investigated to gain understanding of their high piezoelectric activity. The electrostrictive coefficient Q33 of the BZT-xBCT ceramics was observed to be around 0.04 m4/C2, twice that reported for Pb(Zr,Ti)O3-based ceramics. The Q33 was found to be quite stable with respect to temperature and composition for the BZT-xBCT ceramics. The addition of Fe3+ dopant to the ceramics greatly decreased their Curie temperature without affecting their Q33, which remained 0.04 m4/C2. Moreover, a high and hysteresis-free electric-field-induced strain was obtained for 2 at. % Fe-doped BZT-0.5BCT ceramics at room temperature, caused by their high Q33 coefficient and lower-than-room-temperature Curie temperature. The small-signal M33 coefficient of 2 at. % Fe-doped BZT-0.5BCT ceramics was found to be 1.5 × 10-16 m2/V2 (0.32 × 10-16 m2/V2 for undoped counterpart). These results indicate that 2 at. % Fe-doped BZT-0.5BCT ceramics have great potential as alternatives for hard Pb(Zr,Ti)O3 ceramics in actuator applications, where reproducible and non-hysteretic deformation responses are required.

Li, Fei; Jin, Li; Guo, Runping

2014-12-01

56

Breakthrough: Lead-free Solder  

ScienceCinema

Ames Laboratory senior metallurgist Iver Anderson explains the importance of lead-free solder in taking hazardous lead out of the environment by eliminating it from discarded computers and electronics that wind up in landfills. Anderson led a team that developed a tin-silver-copper replacement for traditional lead-tin solder that has been adopted by more than 50 companies worldwide.

Anderson, Iver

2013-03-01

57

Breakthrough: Lead-free Solder  

SciTech Connect

Ames Laboratory senior metallurgist Iver Anderson explains the importance of lead-free solder in taking hazardous lead out of the environment by eliminating it from discarded computers and electronics that wind up in landfills. Anderson led a team that developed a tin-silver-copper replacement for traditional lead-tin solder that has been adopted by more than 50 companies worldwide.

Anderson, Iver

2012-01-01

58

Active Noise Control Using Piezoelectric Actuators in Hard Disk Drives  

Microsoft Academic Search

With the increasing use of electromechanical microsystems, such as hard disk drives, CD-ROM drives, and DVD drives in the consumer electronics industry, there is a growing demand for quieter products. The noise emitted from these devices may originate from the vibration of mechanical components in operation, such as bearings, gears, and actuators. The vibration is then transmitted to other parts

Feng Gao; Ying Yan; Fook Fah Yap

2003-01-01

59

Structure and electrical properties of Bi 0.5Na 0.5TiO 3–BaTiO 3–Bi 0.5Li 0.5TiO 3 lead-free piezoelectric ceramics  

Microsoft Academic Search

Lead-free ceramics (1–x–y)Bi0.5Na0.5TiO3–xBaTiO3–yBi0.5Li0.5TiO3 have been prepared by a conventional ceramic technique, and their structure and electrical properties have been studied. The results of XRD measurement show that Ba2+ and Li+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a pure perovskite structure. With x increasing from 0.02 to 0.12, the ceramics transform gradually from rhombohedral phase to

Dunmin Lin; K. W. Kwok; H. L. W. Chan

2008-01-01

60

Structure, electrical properties and depolarization temperature of (Bi 0.5Na 0.5)TiO 3–BaTiO 3 lead-free piezoelectric ceramics  

Microsoft Academic Search

Lead-free ceramics (1?x)Bi0.5Na0.5TiO3–xBaTiO3 have been prepared by a conventional solid reaction method, and their structure, electrical properties and depolarization temperature have been studied. The results of X-ray diffraction reveal that Ba2+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a pure perovskite structure, and a morphotropic phase boundary (MPB) exists at 0.06

Chenggang Xu; Dunmin Lin; K. W. Kwok

2008-01-01

61

Understanding the role of A-site and B-site cations on piezoelectric instability in lead--free (1-x) BaTiO3 -- xA(Cu1/3Nb2/3)O3 (A = Sr, Ca, Ba) solid solutions  

NASA Astrophysics Data System (ADS)

This study provides fundamental understanding of the enhanced piezoelectric instability in lead-free piezoelectric (1-x) BaTiO3-xA(Cu1/3Nb2/3)O3(A: Sr, Ba and Ca and x = 0.0-0.03) solid solutions. These compositions were found to exhibit large longitudinal piezoelectric constant (d33) of ˜330 pC/N and electromechanical planar coupling constant (kp) ˜ 46% at room temperature. The X-ray diffraction coupled with atomic pair distribution functions (PDF)s indicated increase in local polarization. Raman scattering and electron paramagnetic resonance (EPR) analysis revealed that substitutions on A and B-site both substantially perturbed the local octahedral dynamics and resulted in localized nano polar regions with lower symmetry. The presence of nano domains and local structural distortions smears the Curie peak resulting in diffuse order-disorder type phase transitions. The effect of these distortions on the variations in physical property was modeled and analyzed within the context of nanodomains and phase transitions. *spriya@vt.edu

Maurya, Deepam; Zhou, Yuan; Priya, Shashank

2013-03-01

62

Orientation-dependent piezoelectric properties in lead-free epitaxial 0.5BaZr{sub 0.2}Ti{sub 0.8}O{sub 3}-0.5Ba{sub 0.7}Ca{sub 0.3}TiO{sub 3} thin films  

SciTech Connect

Orientation-engineered 0.5BaZr{sub 0.2}Ti{sub 0.8}O{sub 3}-0.5Ba{sub 0.7}Ca{sub 0.3}TiO{sub 3} (BZT-BCT) thin films were deposited on La{sub 0.7}Sr{sub 0.3}MnO{sub 3}-coated SrTiO{sub 3} single-crystalline (001), (110), and (111) substrates by off-axis radio-frequency magnetron sputtering. X-ray diffraction confirmed a highly epitaxial growth of all the as-deposited films. It is believed the strong orientation dependence of ferroelectric and piezoelectric properties on the films is attributed to the relative alignment of crystallites and spontaneous polarization vector. The optimal ferroelectric response lies in the [001] direction, whereas a comparatively large effective piezoelectric coefficient d{sub 33,eff} of 100.1 ± 5 pm/V was attained in [111] BZT-BCT thin film, suggesting its potential application for high-performance lead-free piezoelectric devices.

Luo, B. C. [School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia) [School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia); School of Science, Northwestern Polytechnical University, Xi'an 710072 (China); Wang, D. Y.; Li, S. [School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia)] [School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052 (Australia); Duan, M. M. [School of Science, Northwestern Polytechnical University, Xi'an 710072 (China)] [School of Science, Northwestern Polytechnical University, Xi'an 710072 (China)

2013-09-16

63

Microstructure, dielectric and piezoelectric properties of (K 0.5 Na 0.5 )NbO 3 Ba(Ti 0.95 Zr 0.05 )O 3 lead-free ceramics with CuO sintering aid  

Microsoft Academic Search

Using an ordinary ceramic fabrication technique, we fabricated lead-free (1-x)(K0.5Na0.5)NbO3-xBa(Ti0.95Zr0.05)O3 ceramics with CuO sintering aid . Ba(Ti0.95Zr0.05)O3 diffuses into (K0.5Na0.5)NbO3 to form a new solid solution. The ceramics with perovskite structure possess orthorhombic phase at x?0.04 and become tetragonal\\u000a phase at x?0.06. Both the paraelectric cubic–ferroelectric tetragonal and the ferroelectric tetragonal–ferroelectric orthorhombic\\u000a phase transition temperatures decrease with increasing the concentration

D. Lin; K. W. Kwok; H. L. W. Chan

2007-01-01

64

Structure, electrical properties and temperature characteristics of Bi 0.5 Na 0.5 TiO 3 –Bi 0.5 K 0.5 TiO 3 –Bi 0.5 Li 0.5 TiO 3 lead-free piezoelectric ceramics  

Microsoft Academic Search

(1?x?y)Bi0.5Na0.5TiO3–xBi0.5K0.5TiO3– yBi0.5Li0.5TiO3 lead-free piezoelectric ceramics have been prepared by an ordinary sintering technique, and their structure, electrical properties,\\u000a and temperature characteristics have been studied systematically. The ceramics can be well-sintered at 1050–1150?°C. The increase\\u000a in K+ concentration decreases the grain-growth rate and promotes the formation of grains with a cubic shape, while the addition\\u000a of Li+ decreases greatly the sintering

Dunmin Lin; Qiaoji Zheng; Chenggang Xu; K. W. Kwok

2008-01-01

65

A piezoelectric quad-morph actuated suspension for hard disk drives  

NASA Astrophysics Data System (ADS)

This paper presents a new milli-actuator using a piezoelectric quad-morph for fine head positioning in hard disk drives (HDDs). The newly proposed piezoelectric quad-morph is configured to produce a diagonal actuation, driving a parallel mechanism embodied into a suspension base plate into a lateral stroke. Finite element modeling shows the actuated suspension achieves a high sway frequency of 13 kHz and an adequate stroke. A parametric study shows that extending the lengths of the quad-morph and the parallel beams can improve both the sway frequency and the lateral stroke. The actuated suspension can also be reinforced with ribs for enhancing shock resistance and dynamic performance, yet without compromising lateral stroke generation. A prototype of the new design is fabricated and manually assembled using a bulk piezoelectric plate and a photo-chemically machined 0.1 mm thick stainless steel load beam. The driving principle of the quad-morph is tested and proven a viable and economical method to accomplish fine head positioning.

Lau, Gih Keong; Du, Hejun

2006-09-01

66

Electrical properties of lead-free 0.98(Na0.5K0.5)NbO3-0.02Ba(Zr0.52Ti0.48)O3 piezoelectric ceramics by optimizing sintering temperature  

PubMed Central

Lead-free 0.98(Na0.5K0.5)NbO3-0.02Ba(Zr0.52Ti0.48)O3 [0.98NKN-0.02BZT] ceramics were fabricated by the conventional mixed oxide method with sintering temperature at 1,080°C to 1,120°C. The results indicate that the sintering temperature obviously influences the structural and electrical properties of the sample. For the 0.98NKN-0.02BZT ceramics sintered at 1,080°C to 1,120°C, the bulk density increased with increasing sintering temperature and showed a maximum value at a sintering temperature of 1,090°C. The dielectric constant, piezoelectric constant [d33], electromechanical coupling coefficient [kp], and remnant polarization [Pr] increased with increasing sintering temperature, which might be related to the increase in the relative density. However, the samples would be deteriorated when they are sintered above the optimum temperature. High piezoelectric properties of d33 = 217 pC/N, kp = 41%, dielectric constant = 1,951, and ferroelectric properties of Pr = 10.3 ?C/cm2 were obtained for the 0.98NKN-0.02BZT ceramics sintered at 1,090°C for 4 h. PMID:22221445

2012-01-01

67

Domain wall motion and electromechanical strain in lead-free piezoelectrics: Insight from the model system (1 ? x)Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} using in situ high-energy X-ray diffraction during application of electric fields  

SciTech Connect

The piezoelectric compositions (1 ? x)Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} (BZT-xBCT) span a model lead-free morphotropic phase boundary (MPB) between room temperature rhombohedral and tetragonal phases at approximately x?=?0.5. In the present work, in situ X-ray diffraction measurements during electric field application are used to elucidate the origin of electromechanical strain in several compositions spanning the tetragonal compositional range 0.6???x???0.9. As BCT concentration decreases towards the MPB, the tetragonal distortion (given by c/a-1) decreases concomitantly with an increase in 90° domain wall motion. The increase in observed macroscopic strain is predominantly attributed to the increased contribution from 90° domain wall motion. The results demonstrate that domain wall motion is a significant factor in achieving high strain and piezoelectric coefficients in lead-free polycrystalline piezoelectrics.

Tutuncu, Goknur [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Li, Binzhi [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, California 95616 (United States); Bowman, Keith [Illinois Institute of Technology, Armour College of Engineering, Chicago, Illinois 60616 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Jones, Jacob L., E-mail: JacobJones@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

2014-04-14

68

Structure, electrical properties and temperature characteristics of Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3-Bi0.5Li0.5TiO3 lead-free piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

(1- x- y)Bi0.5Na0.5TiO3- xBi0.5K0.5TiO3- yBi0.5Li0.5TiO3 lead-free piezoelectric ceramics have been prepared by an ordinary sintering technique, and their structure, electrical properties, and temperature characteristics have been studied systematically. The ceramics can be well-sintered at 1050-1150 °C. The increase in K+ concentration decreases the grain-growth rate and promotes the formation of grains with a cubic shape, while the addition of Li+ decreases greatly the sintering temperature and assists in the densification of BNT-based ceramics. The results of XRD diffraction show that K+ and Li+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a pure perovskite structure. As x increases from 0.05 to 0.50, the ceramics transform gradually from rhombohedral phase to tetragonal phase and consequently a morphotropic phase boundary (MPB) is formed at 0.15? x?0.25. The concentration y of Li+ has no obvious influence on the crystal structure of the ceramics. Compared with pure Bi0.5Na0.5TiO3, the partial substitution of K+ and Li+ for Na+ lowers greatly the coercive field E c and increases the remanent polarization P r of the ceramics. Because of the MPB, lower E c and large P r, the piezoelectricity of the ceramics is improved significantly. For the ceramics with the compositions near the MPB ( x=0.15-0.25 and y=0.05-0.10), the piezoelectric properties become optimum: piezoelectric coefficient d 33=147-231 pC/N and planar electromechanical coupling factor k P=20.2-41.0%. In addition, the ceramics exhibit relaxor characteristic, which probably results from the cation disordering in the 12-fold coordination sites. The depolarization temperature T d shows a strong dependence on the concentration x of K+ and reaches the lowest values at the MPB. The temperature dependences of the ferroelectric and dielectric properties at high temperatures may imply that the ceramics may contain both the polar and non-polar regions at temperatures above T d.

Lin, Dunmin; Zheng, Qiaoji; Xu, Chenggang; Kwok, K. W.

2008-11-01

69

LEAD FREE SOLDERING ON CONTACT PADS  

Microsoft Academic Search

In this article are presented results from the investigations of some peculiarities in the process of soldering on small topological forms in PCBs. The investigation is dedicated to the surface mount technology and deals with lead contained and lead free solder alloy pastes. Attention is paid on the implementation of contact pads with lead free surface finish. For this purpose

Valentin Hristov Videkov; Svetozar Krastev Andreev; Nikola Stefanov

70

Long ranged structural modulation in the pre-morphotropic phase boundary cubic-like state of the lead-free piezoelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}-BaTiO{sub 3}  

SciTech Connect

The nature of the pre-morphotropic phase boundary (MPB) cubic-like state in the lead-free piezoelectric ceramics (1?x)Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}-(x)BaTiO{sub 3} at x???0.06 has been examined in detail by electric field and temperature dependent neutron diffraction, x-ray diffraction, dielectric and ferroelectric characterization. The superlattice reflections in the neutron diffraction patterns cannot be explained with the tetragonal P4bm and the rhombohedral (R3c) phase coexistence model. The cubic like state is rather a result of long ranged modulated complex octahedral tilt. This modulated structure exhibits anomalously large dielectric dispersion. The modulated structure transforms to a MPB state on poling. The field-stabilized MPB state is destroyed and the modulated structure is restored on heating the poled specimen above the Vogel-Fulcher freezing temperature. The results show the predominant role of competing octahedral tilts in determining the nature of structural and polar states in Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}-based ferroelectrics.

Garg, Rohini; Narayana Rao, Badari; Ranjan, Rajeev, E-mail: rajeev@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Senyshyn, Anatoliy [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, Lichtenbergestrasse 1, D-85747 Garching b. München (Germany)

2013-12-21

71

Microstructure Design of Lead-Free Piezoelectric R. E. Garcia,,  

E-print Network

University, West Lafayette, IN 47907-2044 : Toyota Research Institute of North America, Ann Arbor, MI 48105 : Toyota Central Research & Development Laboratories, Inc., Nagatuke, Aichi, 480-1190, Japan : Toyota

Rohrer, Gregory S.

72

NASA DOD Lead Free Electronics Project  

NASA Technical Reports Server (NTRS)

The primary'technical objective of this project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of: Packages (e.g., Thin Small Outline Package [TSOP], Ball Grid Array [BGA], Plastic Dual In-line Package [PDIPD assembled and reworked with lead-free alloys Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with mixed (lead/lead-free) alloys.

Kessel, Kurt R.

2008-01-01

73

Ferroelastic domains in lead-free barium zirconate titanate - barium calcium titanate piezoceramics  

NASA Astrophysics Data System (ADS)

Piezoelectricity was first discovered by Pierre and Jaque Curie in the year 1880. Nowadays, piezoelectric materials are used in many application such as high voltage generation in gas igniters, actuation in micro-positioning devices, generation and detection of acoustic waves, emitters and receivers for sonar technology, ultrasonic cleaning, ultrasound medical therapy, and micropumps for ink-jet printers. The most commonly used piezoelectric material since the 1950's is the solid solution system lead zirconate titanate (PZT) that offers high piezoelectric performance under a large range of operating conditions. However, the toxicity of lead requires the replacement of PZT. The studied lead-free alternatives are commonly based on potassium sodium niobate (KNN) and bismuth sodium titanate (BNT), and more recently zirconium and calcium substituted barium titanate (BZT-BCT). The BZT-BCT system exhibits large piezoelectric coefficients that can exceed even those of most PZT compositions under certain conditions. Piezoelectricity was first discovered by Pierre and Jaque Curie in the year 1880. Nowadays, piezoelectric materials are used in many application such as high voltage generation in gas igniters, actuation in micro-positioning devices, generation and detection of acoustic waves, emitters and receivers for sonar technology, ultrasonic cleaning, ultrasound medical therapy, and micropumps for ink-jet printers. The most commonly used piezoelectric material since the 1950's is the solid solution system lead zirconate titanate (PZT) that offers high piezoelectric performance under a large range of operating conditions. However, the toxicity of lead requires the replacement of PZT. The studied lead-free alternatives are commonly based on potassium sodium niobate (KNN) and bismuth sodium titanate (BNT), and more recently zirconium and calcium substituted barium titanate (BZT-BCT). The BZT-BCT system exhibits large piezoelectric coefficients that can exceed even those of most PZT compositions under certain conditions.

Ehmke, Matthias Claudius

74

Accelerated Aging of Lead-Free Propellant  

NASA Technical Reports Server (NTRS)

Following higher than expected 2-NDPA depletion rates in a lead-free doublebase formulation (RPD-422), an accelerated aging study was conducted to verify the depletion rates. A test plan was prepared to compare the aging characteristics of lead-free propellant and NOSIH-AA2. The study was also designed to determine which lead-free ballistic modifiers accelerated 2-NDPA depletion. The increased depletion rate occurred in propellants containing monobasic copper salicylate. Four lead-free propellants were then formulated to improved aging characteristics over previous lead-free propellant formulations. The new formulations reduced or replaced the monobasic copper salicylate. The new formulations had improved aging characteristics. Their burn rates, however, were unacceptable for use in a 2.75 inch rocket. To compare aging characteristics, stabilizer depletion rates of RPD-422, AA2, M28, and RLC 470/6A were measured or taken from the literature. The data were fit to a kinetic model. The model contained first and zero order terms which allowed the stabilizer concentration to go to zero. In the model, only the concentration of the primary stabilizer was considered. Derivatives beyond the first nitrated or nitroso derivative of 2-NPDA were not considered. The rate constants were fit to the Arrhenius equation and extrapolated to lower temperatures. The time to complete stabilizer depletion was estimated using the kinetic model. The four propellants were compared and the RPD-422 depleted faster at 45 C than both A22 and M28. These types of predictions depend on the validity of the model and on confidence in the Arrhenius relationship holding at lower temperatures. At 45 C, the zero order portion of the model dominates the depletion rate.

Furrow, Keith W.; Jervey, David D.

2000-01-01

75

Comparative study of 2mol% Li- and Mn-substituted lead-free potassium sodium niobate ceramics  

NASA Astrophysics Data System (ADS)

The effect of Li and Mn substitution on the dielectric, ferroelectric and piezoelectric properties of lead free K0.5Na0.5NbO3 (KNN) was investigated. Samples were prepared using a conventional solid state reaction method. The sintering temperature for all the samples was 1050°C. The optimum doping concentration for the enhancement of different properties without the introduction of any other co-dopants such as Ti, Sb, and La was investigated. X-ray diffraction analysis confirmed that all the samples crystallize in a single phase perovskite structure. The dielectric properties were investigated as a function of temperature and applied electric field frequency. Compared with Li-substituted KNN (KLNN), Mn-substituted KNN (KMNN) exhibited a higher dielectric constant ? max (i.e., 4840) at its critical transition temperature T c (i.e., 421°C) along with a lower value of tangent loss at 10 kHz and greater values of saturation polarisation P s (i.e., 20.14 ?C/cm2) and remnant polarisation P r (i.e., 15.48 ?C/cm2). The piezoelectric constant ( d 33) of KMNN was 178 pC/N, which is comparable to that of lead-based hard ceramics. The results presented herein suggest that B-site or Mn substitution at the optimum concentration results in good enhancement of different properties required for materials used in memory devices and other applications.

Dahiya, Asha; Thakur, O. P.; Juneja, J. K.; Singh, Sangeeta; Dipti

2014-12-01

76

First-Principles Calculation of Lead-Free Perovskite SnTiO3  

NASA Astrophysics Data System (ADS)

The phonon spectra, band structure and density of states of cubic perovskite SnTiO3 were investigated using first-principles density functional theory (DFT) computation. The potential energy curves of cations displacement and the formation energy of Sn substitution to B-site were calculated to estimate the structure stability. The results indicate that perovskite SnTiO3 is a promising ferroelectric end member for lead-free piezoelectric materials and applications.

Ye, Hongjun; Zhang, Ruizhi; Wang, Dawei; Cui, Yu; Wei, Jie; Wang, Chunlei; Xu, Zhuo; Qu, Shaobo; Wei, Xiaoyong

2013-09-01

77

Lead-free bearing alloys for engine applications  

NASA Astrophysics Data System (ADS)

Recent developments to reduce the fuel consumption, emission and air pollution, size and weight of engines for automotive, truck, ship propulsion and electrical power generation lead to temperature and load conditions within the engines that cannot be borne by conventional bearings. Presently, only costly multilayer bearings with electroplated or sputtered surface coatings can cope with the load/speed combinations required. Ecological considerations in recent years led to a ban by the European Commission on the use of lead in cars a problem for the standard bronze-lead bearing material. This MAP project is therefore developing an aluminium-based lead-free bearing material with sufficient hardness, wear and friction properties and good corrosion resistance. Only alloys made of components immiscible in the molten state can meet the demanding requirements. Space experimentation plays a crucial role in optimising the cast microstructure for such applications.

Ratke, Lorenz; Ågren, John; Ludwig, Andreas; Tonn, Babette; Gránásy, László; Mathiesen, Ragnvald; Arnberg, Lars; Anger, Gerd; Reifenhäuser, Bernd; Lauer, Michael; Garen, Rune; Gust, Edgar

2005-10-01

78

Rotary Multilayer Split Morph---A Piezoelectric Microactuator for Dual-Stage Actuation Systems in High Track Density Hard Disk Drives  

Microsoft Academic Search

A novel annular rotary piezoelectric microactuator has been proposed for a dual-stage actuation system for future high track density hard disk drives. The microactuator is designed to be mounted on a flexure tongue and drives a slider directly to perform high-frequency track following. The configuration and operation of the microactuator are described. The controllable stroke and the resonance frequency of

Zhihong Wang; Weiguang Zhu; Ooi Kiang Tan; Xi Yao

2001-01-01

79

Epitaxial Stabilization of a Morphotropic Phase Boundary in Lead-Free Ferroelectric Thin Films  

NASA Astrophysics Data System (ADS)

This dissertation details the synthesis and characterization of compressively strained epitaxially grown bismuth ferrite thin films in an effort to improve their piezoelectric properties with the goal of finding a viable lead-free alternative to lead zirconate titanate. It is found that under compressive epitaxial strain a morphotropic phase boundary, the hallmark of high performance piezoelectrics, is stabilized in this material. The structural characterization of these films reveals complex mixed-phase morphologies whereby nearly energetically degenerate monoclinically distorted tetragonal and rhombohedral ferroelectric phases coexist with apparent crystallographically coherent interfaces. This mixed phase morphology is found to be responsive to perturbations both via mechanical indentation and an applied electric field, whereby a reversible phase transition is observed in the films. Electrical characterization of these films indicates a pronounced increase in their piezoelectric and ferroelectric properties.

Zeches, Robert James

80

Lead-Free Surface Finishes for Electronic Components  

E-print Network

Lead-Free Surface Finishes for Electronic Components: Tin Whisker Growth METALS This project degraded by the switch to lead- free technology. In particular, the state of compressive stress and the localized creep response (whisker growth) of tin-based lead-free electrodeposits are being measured

81

NASA-DoD Lead-Free Electronics Project  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the current state of the lead-free electronics project. It characterizes the test articles, which were built with lead-free solder and lead-free component finishes. The tests performed and reported on are: thermal cycling, combine environments testing, mechanical shock testing, vibration testing and drop testing.

Kessel, Kurt

2010-01-01

82

Development of piezoelectric adaptive mirror for hard x-ray nanofocusing  

NASA Astrophysics Data System (ADS)

To construct an adaptive X-ray focusing optical system, we developed an ultraprecise deformable mirror that consists of a substrate, piezoelectric actuators, and 18 electrodes. A one-dimensional focusing test was performed at SPring-8 at 15 keV. The mirror deformation was roughly adjusted by applying voltages determined by a deformation test with a Fizeau interferometer. The shape was then finely corrected based on the shape determined by the pencil-beam method and the phase retrieval method. A focused beam with a full width at half maximum of 120 nm was obtained.

Matsuyama, S.; Kimura, T.; Nakamori, H.; Imai, S.; Sano, Y.; Kohmura, Y.; Tamasaku, K.; Yabashi, M.; Ishikawa, T.; Yamauchi, K.

2012-10-01

83

Research trends in lead-free soldering in the US: NCMS Lead-Free Solder Project  

Microsoft Academic Search

In 1997, the National Center for Manufacturing Sciences Lead-Free Solder Project carried out by a consortium of 11 industrial corporations, academic institutions, and national laboratories completed its four year program to identify, and evaluate alternatives to eutectic tin-lead solder. The goal of the project was to determine whether safe, reliable, nontoxic and cost-effective substitutes exist for lead-bearing solders in electronics

I. Artaki; D. Noctor; J. Mather; S. Schroeder; D. Napp; C. Desantis; W. Desaulnier; Tsung-Yu Pan; L. Felton; M. Palmer; J. Rosser; J. Felty; P. Vianco; J. Greaves; G. Whitten; Yun Zhu; C. Handwerker

1999-01-01

84

Integration of Piezoelectric Sensing and Control for Nano-Scale Vibration Suppression in Hard Disk Drives  

E-print Network

actuated suspension donated by Hutchinson Technology, Inc.suspension for detecting disk flutter and reducing track misregistration, Mi- crosystem Technology (suspension structure in hard-disk drives using a polyvinylidene-flouride actuator and sensor, Measurement Science and Technology

Felix, Sarah Helen

2010-01-01

85

Modeling and control of a dual stage actuator hard disk drive with piezoelectric secondary actuator  

Microsoft Academic Search

High capacity of new magnetic material can be exploited only with a fine servo-positioning of the hard disk heads. This can be achieved by means of dual stage actuation, where the secondary actuator can be realized with different technologies. In this paper, the need for a secondary actuator is proven by explicitly including the nonlinear friction on the voice coil

Roberto Oboe; Alessandro Beghi; Bruno Murari

1999-01-01

86

NASA-DoD Lead-Free Electronics Project  

NASA Technical Reports Server (NTRS)

In response to concerns about risks from lead-free induced faults to high reliability products, NASA has initiated a multi-year project to provide manufacturers and users with data to clarify the risks of lead-free materials in their products. The project will also be of interest to component manufacturers supplying to high reliability markets. The project was launched in November 2006. The primary technical objective of the project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of: - Packages (e.g., TSOP, BOA, PDIP) assembled and reworked with solder interconnects consisting of lead-free alloys - Packages (e.g., TSOP, BOA, PDIP) assembled and reworked with solder interconnects consisting of mixed alloys, lead component finish/lead-free solder and lead-free component finish/SnPb solder.

Kessel, Kurt R.

2009-01-01

87

NASA-DoD Lead-Free Electronics Project  

NASA Technical Reports Server (NTRS)

In response to concerns about risks from lead-free induced faults to high reliability products, NASA has initiated a multi-year project to provide manufacturers and users with data to clarify the risks of lead-free materials in their products. The project will also be of interest to component manufacturers supplying to high reliability markets. The project was launched in November 2006. The primary technical objective of the project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of: - Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with solder interconnects consisting of lead-free alloys - Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with solder interconnects consisting of mixed alloys, lead component finish/lead-free solder and lead-free component finish/SnPb solder.

Kessel, Kurt R.

2009-01-01

88

NASA-DoD Lead-Free Electronics Project  

NASA Technical Reports Server (NTRS)

In response to concerns about risks from lead-free induced faults to high reliability products, NASA has initiated a multi-year project to provide manufacturers and users with data to clarify the risks of lead-free materials in their products. The project will also be of interest to component manufacturers supplying to high reliability markets. The project was launched in November 2006. The primary technical objective of the project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of: (1) Packages (e.g., Thin Small Outline Package [TSOP], Ball Grid Array [BGA], Plastic Dual In-line Package [PDIP]) assembled and reworked with solder interconnects consisting of lead-free alloys (2) Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with solder interconnects consisting of mixed alloys, lead component finish/lead-free solder and lead-free component finish/SnPb solder

Kessel, Kurt

2009-01-01

89

Lead-free KNbO3 ferroelectric nanorod based flexible nanogenerators and capacitors.  

PubMed

In spite of high piezoelectricity, only a few one-dimensional ferroelectric nano-materials with perovskite structure have been used for piezoelectric nanogenerator applications. In this paper, we report high output electrical signals, i.e. an open-circuit voltage of 3.2 V and a closed-circuit current of 67.5 nA (current density 9.3 nA cm(-2)) at 0.38% strain and 15.2% s(-1) strain rate, using randomly aligned lead-free KNbO(3) ferroelectric nanorods (~1 ?m length) with piezoelectric coefficient (d(33) ~ 55 pm V (-1)). A flexible piezoelectric nanogenerator is mainly composed of KNbO(3)-poly(dimethylsiloxane) (PDMS) composite sandwiched by Au/Cr-coated polymer substrates. We deposit a thin poly(methyl methacrylate) (PMMA) layer between the KNbO(3)-PDMS composite and the Au/Cr electrode to completely prevent dielectric breakdown during electrical poling and to significantly reduce leakage current during excessive straining. The flexible KNbO(3)-PDMS composite device shows a nearly frequency-independent dielectric constant (~3.2) and low dielectric loss (<0.006) for the frequency range of 10(2)-10(5) Hz. These results imply that short and randomly aligned ferroelectric nanorods can be used for a flexible high output nanogenerator as well as high-k capacitor applications by performing electrical poling and further optimizing the device structure. PMID:22922486

Jung, Jong Hoon; Chen, Chih-Yen; Yun, Byung Kil; Lee, Nuri; Zhou, Yusheng; Jo, William; Chou, Li-Jen; Wang, Zhong Lin

2012-09-21

90

Characterization of Lead-Free B2O3 Doped Barium Stannate Titanate Ceramics  

NASA Astrophysics Data System (ADS)

Lead-free barium stannate titanate ceramics doped with 2 wt% of B2O3 were prepared via a solid state sintering. The optimum condition for the preparation was carried out. Properties of the lead free material were characterized by various methods. The high dielectric constant >14000 with low tan ? 0.040 was observed at 34° C for the samples prepared at the optimum condition. Plots of dielectric permittivity as a function of temperature showed that the ceramics exhibit a diffuse ferroelectric-paraelectric phase transition. The dielectric constant was also measured as a function of electric field. The dielectric-electric field measurement indicated that this material exhibits a high tunability. In addition, mechanical property such as hardness was investigated. Relation between grain size and hardness of the ceramics was found to obey the Hall-Petch equation: Hv = 0.07+12.9G-1/2.

Tawichai, N.; Pengpat, K.; Rujijanagul, G.

2009-07-01

91

NASA-DoD Lead-Free Electronics Project  

NASA Technical Reports Server (NTRS)

Original Equipment Manufacturers (OEMs), depots, and support contract ors have to be prepared to deal with an electronics supply chain that increasingly provides parts with lead-free finishes, some labeled no differently and intermingled with their SnPb counterparts. Allowance of lead-free components presents one of the greatest risks to the r eliability of military and aerospace electronics. The introduction of components with lead-free terminations, termination finishes, or cir cuit boards presents a host of concerns to customers, suppliers, and maintainers of aerospace and military electronic systems such as: 1. Electrical shorting due to tin whiskers 2. Incompatibility of lead-f ree processes and parameters (including higher melting points of lead -free alloys) with other materials in the system 3. Unknown material properties and incompatibilities that could reduce solder joint reli ability As the transition to lead-free becomes a certain reality for military and aerospace applications, it will be critical to fully un derstand the implications of reworking lead-free assemblies.

Kessel, Kurt

2010-01-01

92

Investigation of MPB region in lead free BLNT-BCT system through XRD and Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Lead free piezoelectrics [1-x{(Bi0.96La0.04)0.5Na0.5TiO3}?x(Ba0.90Ca0.10TiO3)] (BLNT-BCT) with compositions x ? 0.20 have been synthesized by a semi-wet route and the compositions around the MPB region have been systematically investigated using x-ray diffraction and Raman spectroscopy. X-ray diffraction analysis confirms phase formation without any traces of secondary phases. Rietveld refinement of x-ray diffraction data revealed different structural symmetry for a different range of compositions viz., (i) rhombohedral (R3c) [x ? 0.08] (ii) rhombohedral (R3c) + tetragonal (P4mm) (MPB) [0.10 ? x ? 0.15] (iii) tetragonal (P4mm) [0.15 < x ? 0.20], which is confirmed by Raman spectroscopy. The structural phase transitions have been correlated with piezoelectric properties and the composition with x = 0.12 depicts better piezoelectric properties amongst studied compositions, which is attributed to the coexistence of rhombohedral and tetragonal phases.

Pal, V.; Thakur, O. P.; Dwivedi, R. K.

2015-02-01

93

Rotary Multilayer Split Morph—A Piezoelectric Microactuator for Dual-Stage Actuation Systems in High Track Density Hard Disk Drives  

NASA Astrophysics Data System (ADS)

A novel annular rotary piezoelectric microactuator has been proposed for a dual-stage actuation system for future high track density hard disk drives. The microactuator is designed to be mounted on a flexure tongue and drives a slider directly to perform high-frequency track following. The configuration and operation of the microactuator are described. The controllable stroke and the resonance frequency of the slider/actuator assembly have been evaluated and optimized by finite-element analysis. The results reveal that the designed actuator/slider assembly should be a promising addition to the dual-stage actuation system.

Wang, Zhihong; Zhu, Weiguang; Tan, Ooi Kiang; Yao, Xi

2001-09-01

94

NASA-DoD Lead-Free Electronics Project  

NASA Technical Reports Server (NTRS)

Original Equipment Manufacturers (OEMs). depots. and support contractors have to be prepared to deal with an electronics supply chain thaI increasingly provides parts with lead-free finishes. some labeled no differently and intenningled with their SnPb counterparts. Allowance oflead-free components presents one of the greatest risks to the reliability of military and aerospace electronics. The introduction of components with lead-free lenninations, tennination finishes, or circuit boards presents a host of concerns to customers. suppliers, and maintainers of aerospace and military electronic systems such as: 1. Electrical shorting due to tin whiskers; 2. Incompatibility oflead-free processes and parameters (including higher melting points of lead-free alloys) with other materials in the system; and 3. Unknown material properties and incompatibilities that could reduce solder joint re liability.

Kessel, Kurt

2011-01-01

95

Structural And Electrical Analysis Of Lead Free BZT-xBCT Ceramics  

SciTech Connect

A comparative study of structural and electric properties of a recently discovered lead free electroceramic, Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} or BZT-xBCT, was conducted in the entire range from x = 0 to x = 1. This novel ceramic composite is being seen as a genuine understudy for commercially one of the most widely used piezoelectric ceramic, PZT, which is facing worldwide criticism due to its lead toxicity. The new system can be very extensively used like PZT in transduction applications as sensor, actuator and ultrasonic devices apart from numerous other utilities. The XRD, SEM and Ferroelectric studies establish the structural transition and different phases as function of Zr /Ti and Ba /Ca ratios.

Bhardwaj, Chandan; Kumar, Ashvani; Kaur, Davinder [Functional Nanomaterials Research Lab, Department of Physics and Centre of Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

2010-12-01

96

Development of lead-free single-element ultrahigh frequency (170 – 320 MHz) ultrasonic transducers  

PubMed Central

This paper presents the design, fabrication and characterization of single-element ultrahigh frequency (UHF) ultrasonic transducers in which the center frequency ranged from 170 to 320 MHz. The center frequency of > 300 MHz is the highest value of lead-free ceramic ultrasonic transducers ever reported. With concern in the environmental pollution of lead-based materials, the transducer elements presented in this work were lead-free K0.5Na0.5NbO3/Bi0.5Na0.5TiO3 (KNN/BNT) composite thick films. All transducers were evaluated in a pulse-echo arrangement. The measured ?6 dB bandwidth of the transducers ranged from 35 to 64 %. With the optimized piezoelectric properties of the composite film, the insertion loss of the UHF transducers was measured and determined to range from ?50 to ?60 dB. In addition to the pulse-echo measurement, a 6-?m tungsten wire phantom was also imaged with a 205 MHz transducer to demonstrate the imaging capability. The measured ?6 dB axial and lateral resolutions were found to be 12 ?m and 50 ?m, respectively. The transducer performance presented in this work is shown to be better or comparable to previously reported results even though the frequency is much higher. PMID:23485349

Lam, Kwok Ho; Ji, Hong Fen; Zheng, Fan; Ren, Wei; Zhou, Qifa; Shung, K. Kirk

2013-01-01

97

Environmental leadership in electronics manufacturing: lead-free and beyond  

Microsoft Academic Search

This paper reviews the strategy and methodology for meeting the challenges of environmental leadership for the transition to WEEE\\/RoHS compliance in electronics manufacturing, including the key compatibility issues involved in lead-free soldering, supply chain compliance, compliance assurance management, design for the environment, and recycling for product end-of-life management.

Dongkai Shangguan

2004-01-01

98

Lead-Free Experiment in a Space Environment  

NASA Technical Reports Server (NTRS)

This Technical Memorandum addresses the Lead-Free Technology Experiment in Space Environment that flew as part of the seventh Materials International Space Station Experiment outside the International Space Station for approximately 18 months. Its intent was to provide data on the performance of lead-free electronics in an actual space environment. Its postflight condition is compared to the preflight condition as well as to the condition of an identical package operating in parallel in the laboratory. Some tin whisker growth was seen on a flight board but the whiskers were few and short. There were no solder joint failures, no tin pest formation, and no significant intermetallic compound formation or growth on either the flight or ground units.

Blanche, J. F.; Strickland, S. M.

2012-01-01

99

Rare earths in lead-free oxyfluoride germanate glasses.  

PubMed

Spectroscopic properties of rare earths in lead-free oxyfluoride germanate glasses were studied. The absorption and luminescence spectra of Eu(3+), Pr(3+) and Er(3+) ions were examined as a function of BaF? concentration and several spectroscopic parameters for rare earths were determined. The ratio of integrated luminescence intensity of the (5)D??(7)F? transition to that of the (5)D??(7)F? transition of Eu(3+) decrease significantly with increasing BaF? content. The absorption (Er(3+)) and emission (Pr(3+)) 'hypersensitive transitions' of rare earths are shifted in direction to shorter wavelengths with increasing BaF? content in glass composition. Emission spectra and their decays corresponding to the main (4)I??/??(4)I??/? laser transition of Er(3+) were also analyzed. Quite long-lived NIR luminescence of Er(3+) is observed for lead-free glass samples with low BaF? concentration. PMID:25088539

Pisarski, Wojciech A; Pisarska, Joanna; Dorosz, Dominik; Dorosz, Jan

2015-01-01

100

Development of fluxes for lead-free solders containing zinc  

Microsoft Academic Search

New lead-free solders based on the Sn-Zn eutectic (92 wt. pct Sn - 8 wt. pct Zn) are promising candidates to replace near-eutectic tin-lead solders because these solders are less expensive than alternatives such as Sn-Ag eutectic base solders and the melting point of the tin-zinc eutectic (198 C) is much closer to melting point of commonly used tin-lead eutectic

S. Vaynman; M. E. Fine

1999-01-01

101

Growth and characterization of lead-free ferroelectric (K,Na,Li)(Nb,Ta,Sb)O3 single crystal  

NASA Astrophysics Data System (ADS)

In this work, a large size lead-free piezoelectric single crystal, (K,Na,Li)(Nb,Ta,Sb)O3 (KNLNTS) with the dimensions of 8.5×8.5×13.5 mm3 was successfully grown by the top-seeded solution growth method. This KNLNTS single crystal with high compositional homogeneity is in the tetragonal phase at room temperature. The Curie temperature TC of the tetragonal-cubic phase transition temperature is 210 °C. The piezoelectric coefficients and electromechanical coupling factors of the [001]C oriented KNLNTS single crystal are d33=172.55 pC/N, d31=-71.90 pC/N, k31=0.327, k33=0.523, and kt=0.541. In addition, the crystal shows good thermal stability so that it can be used for making high temperature electromechanical devices.

Wang, Junjun; Zheng, Limei; Yang, Bin; Wang, Rui; Huo, Xiaoqing; Sang, Shijing; Wu, Jie; Chang, Yunfei; Ning, Huanpo; Lv, Tianquan; Cao, Wenwu

2015-01-01

102

Underfill process development for lead free flip chip assembly  

NASA Astrophysics Data System (ADS)

Underfills are used to enhance the long-term reliability of the flip-chip solder joints. More specifically, the function of the underfill is to couple the chip to the substrate, wherein the shear stresses experienced by the solder joints are converted to bending stresses. The underfill flows under the die due to the influence of strong capillary forces. The flow of the underfill under the chip depends on various factors such as the viscosity of the underfill, contact angle, surface tension, temperature, underfill gap, substrate design, bump pattern, bump density, and size of the chip. The flow of underfill is also influenced by the cleanliness of the substrate, the cleanliness of the underside of the chip, and the flux residues. The interaction between the underfill and the substrate affects not only gap filling, but also the filleting of the underfill. Similarly, the underfill-flux interaction directly affects the quality of underfilling and the reliability of the flip chip assembly. In the case of lead free flip chip assembly, the major concerns vis-a-vis process development for a large chip with a small bump pitch (less than 190 mum) include lower throughput, voiding under the chip, and critical reliability performance. The principal objective of this research endeavor was to investigate the fundamental issues that relate to the process and reliability aspects of underfilling of lead free flip chip assemblies. In order to develop a robust underfilling process, the effect of different process parameters and their interaction with the material properties were studied. In order to improve the compatibility between the underfill and the flux, a new epoxy flux that was compatible with the lead free assembly process was developed. The performance of the epoxy was also compared with the performance of various rosin based fluxes. This study also helped in identifying the critical parameters that can affect the assembly yields. This research endeavor successfully contributed towards defining dispensing process windows for the underfills that were compatible with the lead free process. In conclusion, the proposed research contributed towards the development of the fundamental understanding of the capillary underfilling process for lead free flip chip assemblies.

Chaware, Raghunandan

103

Ferroelectric and octahedral tilt twin disorder and the lead-free piezoelectric, sodium potassium niobate system  

SciTech Connect

Using electron diffraction, trends in the local structural behaviour of the K{sub x}Na{sub 1-x}NbO{sub 3} (KNN x) 'solid solution' system are investigated and interpreted using an order/disorder based theoretical framework. At room temperature, electron diffraction shows a single plane of transverse polarised, diffuse intensity perpendicular to [0 1 0]{sub p} Low-Asterisk (p for parent sub-structure) across the entire phase diagram, indicative of ferroelectric disorder along the [0 1 0]{sub p} direction co-existing with long range ferroelectric order along the orthogonal [1 0 0]{sub p} and [0 0 1]{sub p} directions. An additional characteristic pattern of diffuse scattering is also observed, involving rods of diffuse intensity running along the [1 0 0]{sub p}* and [0 0 1]{sub p}* directions of the perovskite sub-structure and indicative of octahedral tilt disorder about the [1 0 0]{sub p} and [0 0 1]{sub p} axes co-existing with long range ordered octahedral tilting around the [0 1 0]{sub p} direction. A possible crystal chemical explanation for the existence of this latter octahedral tilt disorder is explored through bond valence sum calculations. The possible influence of both types of disorder on the previously refined, room temperature space group/s and average crystal structure/s is examined. - Graphical abstract: [-3,0.-1]p zone axis EDP of K{sub 0.46}Na{sub 0.54}NbO{sub 3} indexed according to both the relevant Pcm21 space groups (no subscripts) and the parent perovskite subcell (denoted by a subscript p). Highlights: Black-Right-Pointing-Pointer Characterises ferroelectric and octahedral tilt disorder in the KNN solid solution. Black-Right-Pointing-Pointer Discusses the possible driving forces for this disorder. Black-Right-Pointing-Pointer Discusses the implications of this disorder for physical properties. Black-Right-Pointing-Pointer Discusses the effects of this disorder on powder diffraction data.

Schiemer, Jason [Research School of Chemistry, The Australian National University, Canberra, ACT 0200 (Australia)] [Research School of Chemistry, The Australian National University, Canberra, ACT 0200 (Australia); Withers, Ray L., E-mail: withers@rsc.anu.edu.au [Research School of Chemistry, The Australian National University, Canberra, ACT 0200 (Australia); Liu, Yun; Yi, Zhiguo [Research School of Chemistry, The Australian National University, Canberra, ACT 0200 (Australia)] [Research School of Chemistry, The Australian National University, Canberra, ACT 0200 (Australia)

2012-11-15

104

Rare earths in lead-free oxyfluoride germanate glasses  

NASA Astrophysics Data System (ADS)

Spectroscopic properties of rare earths in lead-free oxyfluoride germanate glasses were studied. The absorption and luminescence spectra of Eu3+, Pr3+ and Er3+ ions were examined as a function of BaF2 concentration and several spectroscopic parameters for rare earths were determined. The ratio of integrated luminescence intensity of the 5D0 ? 7F2 transition to that of the 5D0 ? 7F1 transition of Eu3+ decrease significantly with increasing BaF2 content. The absorption (Er3+) and emission (Pr3+) ‘hypersensitive transitions’ of rare earths are shifted in direction to shorter wavelengths with increasing BaF2 content in glass composition. Emission spectra and their decays corresponding to the main 4I13/2 ? 4I15/2 laser transition of Er3+ were also analyzed. Quite long-lived NIR luminescence of Er3+ is observed for lead-free glass samples with low BaF2 concentration.

Pisarski, Wojciech A.; Pisarska, Joanna; Dorosz, Dominik; Dorosz, Jan

2015-01-01

105

High-Temperature Piezoelectrics with Large Piezoelectric Coefficients  

NASA Astrophysics Data System (ADS)

High-temperature piezoelectric materials are of interest for sensors and actuators in various industrial applications in which the devices are exposed to high temperature. A lot of research has been conducted in this area to bring forth a suitable piezoelectric material having a high Curie temperature for suitable usage at a high temperature with good piezoelectric properties. This report is an attempt to review the state of the art in high-temperature piezoelectric materials, covering their issues and concerns at elevated temperatures. Among the non-ferroelectric crystal classes, langasite and oxyborate crystals retain their piezoelectricity up to a very high temperature, but their piezoelectric coefficient is much smaller compared to a standard piezoelectric material such as lead zirconate titanate. A similar trend has also been observed in ferroelectric crystal class which shows poor piezoelectricity but retains it until a high temperature. Recent studies on solid solutions of bismuth-based oxides and lead titanate with the chemical formulae Bi(Me3+) O3-PbTiO3 and Bi(Me1Me2)O3-PbTiO3 (Me3+ represents a trivalent cation and Me1 and Me2 are cations having a combined valency of 3) show a much application potential of these materials due to improved piezoelectric property and high Curie temperature. BiScO3-PbTiO3, Bi(Mg0.5Ti0.5)O3-PbTiO3, (Bi(Ni0.5Ti0.5)O3-PbTiO3 and Bi(Zn0.5T0.5)O3-PbTiO3 are some interesting high-temperature piezoelectrics from the group of Bi(Me3+)O3-PbTiO3 and Bi(Me1Me2) O3-PbTiO3 which shows superior piezoelectric properties at high temperatures. Among the lead-free piezoelectrics, (K0.5Na0.5)NbO3 demands a special interest for further studies due to its plausible good piezoelectric property at elevated temperature.

Shinekumar, K.; Dutta, Soma

2014-12-01

106

High-Temperature Piezoelectrics with Large Piezoelectric Coefficients  

NASA Astrophysics Data System (ADS)

High-temperature piezoelectric materials are of interest for sensors and actuators in various industrial applications in which the devices are exposed to high temperature. A lot of research has been conducted in this area to bring forth a suitable piezoelectric material having a high Curie temperature for suitable usage at a high temperature with good piezoelectric properties. This report is an attempt to review the state of the art in high-temperature piezoelectric materials, covering their issues and concerns at elevated temperatures. Among the non-ferroelectric crystal classes, langasite and oxyborate crystals retain their piezoelectricity up to a very high temperature, but their piezoelectric coefficient is much smaller compared to a standard piezoelectric material such as lead zirconate titanate. A similar trend has also been observed in ferroelectric crystal class which shows poor piezoelectricity but retains it until a high temperature. Recent studies on solid solutions of bismuth-based oxides and lead titanate with the chemical formulae Bi(Me3+) O3-PbTiO3 and Bi(Me1Me2)O3-PbTiO3 (Me3+ represents a trivalent cation and Me1 and Me2 are cations having a combined valency of 3) show a much application potential of these materials due to improved piezoelectric property and high Curie temperature. BiScO3-PbTiO3, Bi(Mg0.5Ti0.5)O3-PbTiO3, (Bi(Ni0.5Ti0.5)O3-PbTiO3 and Bi(Zn0.5T0.5)O3-PbTiO3 are some interesting high-temperature piezoelectrics from the group of Bi(Me3+)O3-PbTiO3 and Bi(Me1Me2) O3-PbTiO3 which shows superior piezoelectric properties at high temperatures. Among the lead-free piezoelectrics, (K0.5Na0.5)NbO3 demands a special interest for further studies due to its plausible good piezoelectric property at elevated temperature.

Shinekumar, K.; Dutta, Soma

2015-02-01

107

Lead-Free Propellant for Propellant Actuated Devices  

NASA Technical Reports Server (NTRS)

Naval Surface Warfare Center, Indian Head Division's CAD/PAD Department has been working to remove toxic compounds from our products for about a decade. In 1992, we embarked on an effort to develop a lead-free double base propellant to replace that of a foreign sole source. At the time there were availability concerns. In 1995, the department developed a strategic proposal to include a wider range of products. Efforts included such efforts as removing lead sheathing from linear explosives and replacing lead azide and lead styphnate compounds. This paper will discuss efforts specifically related to developing non-leaded double base propellant for use in various Propellant Actuated Devices (PADs) for aircrew escape systems. The propellants can replace their leaded counterparts, mitigating lead handling, processing, or toxic exposure to the environment and personnel. This work eliminates the use of leaded compounds, replacing them with a more environmentally benign metal-organic salt. Historically double-base propellants have held an advantage over other families of energetic materials through their relative insensitivity of the burning rate to changes in temperature and pressure. This desirable ballistic effect has been obtained with the use of a lead-organic salt alone or in a physical mixture with a copper-organic salt, or more recently with a lead-copper complex. These ballistic modifiers are typically added to the double-base 'paste' prior to gelatinization on heated calendars or one type or another. The effect of constant burning rate over a pressure range is called a 'plateau' while an even more beneficial effect of decreasing burning rate with increasing pressure is termed a 'mesa.' The latter effect results in very low temperature sensitivity of the propellant burning rate. Propellants with such effects are ideal tactical rocket motor propellants. The use of lead compounds poses a concern for the environment and personnel safety due to the metal's toxic nature when introduced into the atmosphere by propellant manufacturing, rocket firings, and disposal. Two separate programs are underway at Indian Head to replace the leaded ballistic modifiers in NOSIH-AA-2 and KU propellants. Although the system requirements were very different, the programs gained valuable information from one another throughout their course.

Goodwin, John L.

2000-01-01

108

Piezoelectric Polymers  

NASA Technical Reports Server (NTRS)

The purpose of this review is to detail the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers; to present the state-of-the-art in piezoelectric polymers and emerging material systems that exhibit promising properties; and to discuss key characterization methods, fundamental modeling approaches, and applications of piezoelectric polymers. Piezoelectric polymers have been known to exist for more than forty years, but in recent years they have gained notoriety as a valuable class of smart materials.

Harrison, J. S.; Ounaies, Z.; Bushnell, Dennis M. (Technical Monitor)

2001-01-01

109

Effect of lead-free solder joint's size and configuration on mechanical properties, microstructure, and aging kinetics  

NASA Astrophysics Data System (ADS)

The properties of Lead-Free solder joints continue to change over a very long time while in service. The assessment of long-term service life of electronics packages invariably misses the effect of solder joint size and configuration, and may thus end up to be seriously misleading. One of the goals of the present research is to develop a fundamental understanding of the effects of solder joint size on the mechanical properties of microstructure and aging kinetics. This understanding will help in the assessment of the reliability of Lead-Free solder joints. For this purpose, two different room temperature properties, namely, shear strength and micro-hardness, are studied and the microstructure is also evaluated to find the correlation between them. These properties are measured before and after aging for different lengths of time at different temperatures. Five common Lead-Free alloys are selected for the present study, which are SAC105, SAC205, SAC305, SnCu and SnAg. The study also addresses effects of solder joint size by focusing on 20 mil (508?m) and 30 mil (760?m) diameter solder spheres reflowed onto solder mask defined OSP coated Cu pads with a typical manufacturing Lead-Free reflow profile. Isothermal aging is conducted for up to 500 hours at temperatures of 70, 100, and 125°C. As expected, the resulting room temperature properties decrease with aging time, and at a faster rate for higher aging temperatures. The acceleration factors that are extracted for the evolution of each property are different for the selected alloy and joint sizes.

Tashtoush, Tariq H.

110

Perovskite lithium and bismuth modified potassium-sodium niobium lead-free ceramics for high temperature applications  

SciTech Connect

[(K{sub (1-x)/2}Na{sub (1-x)/2}Li{sub x}){sub 1-3y}Bi{sub y}]NbO{sub 3} (abbreviated as KNLBN) ceramics were prepared by conventional solid-state sintering. The addition of Li{sup +} and Bi{sup 3+} makes the orthorhombic-tetragonal phase transition temperature (T{sub O-T}) decrease from 200 deg. C for pure (K{sub 0.5}Na{sub 0.5})NbO{sub 3} ceramics to -10 deg. C for KNLBN ceramics (x=0.06, y=0.005), while maintaining high Curie temperature (T{sub C}=455 deg. C) and piezoelectric properties (d{sub 33}=185 pC/N, k{sub p}=0.43, k{sub t}=0.45, {epsilon}{sub 33}{sup T}/{epsilon}{sub 0}=1020, and tan {delta}=0.023) at room temperature. In addition, good temperature stability of electrical properties is obtained in KNLBN ceramics (x=0.06, y=0.005) owing to the decrease of T{sub O-T}. These results indicate that KNLBN (x=0.06, y=0.005) ceramic is a promising lead-free piezoelectric candidate material for high temperature applications.

Du Hongliang; Zhou Wancheng; Luo Fa; Zhu Dongmei; Qu Shaobo; Pei Zhibin [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072 (China); Electronic Materials Research Laboratory, Key Laboratory of Educational Ministry, Xi'an Jiaotong University, Xi'an 710049 (China); The College of Science, Air Force Engineering University, Xi'an 710051 (China)

2007-10-29

111

Piezoelectric valve  

DOEpatents

A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

Petrenko, Serhiy Fedorovich

2013-01-15

112

Thermomigration: An experimental damage mechanics study on nanoelectronic lead free solder alloys  

NASA Astrophysics Data System (ADS)

This dissertation focuses on experimental study of thermomigration in lead-free solder alloys. Thermomigration in microelectronic solder joints was not a concern until significant miniaturization of electronics devices required to run high current densities with smaller solder joint sizes. High current density induces electromigration and Joule heating at the same time. The imbalance of Joule heating generated at top and bottom of solder joint causes a temperature gradient which is large enough to induce thermomigration damage. In the literature, most studies report electromigration induced damage without considering the influence of thermomigration, thus the effect of electromigration and thermomigration can not be individually identified. This dissertation studies the experimental damage mechanics of thermomigration without electromigration by studying formation and destruction of intermetallic compound, and vacancy migration due to diffusion driving forces. Microstructural degradation and hardness testing were used to quantify thermomigration induced damage. After studying material science and physics behind the thermomigration process, using test vehicles, the combined effects of electromigration and thermomigration were studied experimentally. The studies were repeated at a subzero temperatures to see the effect of low temperature on thermomigration and electromigration, and reliability of nanoelectronic solder joints. A new time to failure equation is proposed to show a threshold temperature below which diffusion slows down significantly. By ensuring the solder operating temperature is well kept below the threshold value by proper thermal management, the solder joint life can be extended.

Abdul Hamid, Mohd Foad

113

Thermal Fatigue Assessment of Lead-Free Solder Joints Qiang YU and Masaki SHIRATORI  

E-print Network

Thermal Fatigue Assessment of Lead-Free Solder Joints Qiang YU and Masaki SHIRATORI Department@swan.me.ynu.ac.jp ABSTRACT In this paper the authors have investigated the thermal fatigue reliability of lead-free solder on the initiation and propagation behaviors of fatigue cracks. Furthermore, they also studied the effect of voids

Paris-Sud XI, Université de

114

Lead-free KNbO ferroelectric nanorod based flexible nanogenerators and capacitors  

E-print Network

], and their extensive applications, such as in nano-sensors and nano- actuator/transducers [3]. Among ferroelectric nanoLead-free KNbO 3 ferroelectric nanorod based flexible nanogenerators and capacitors This article.1088/0957-4484/23/37/375401 Lead-free KNbO3 ferroelectric nanorod based flexible nanogenerators and capacitors Jong Hoon Jung1

Wang, Zhong L.

115

Structure and electrical properties of Na1/2Bi1/2TiO3-xK1/2Bi1/2TiO3 lead-free ferroelectric single crystals  

NASA Astrophysics Data System (ADS)

Dielectric, ferroelectric and piezoelectric properties of lead-free Na1/2Bi1/2TiO3-xK1/2Bi1/2TiO3 (NBT-xKBT) ferroelectric single crystals were characterized systematically. With increasing KBT concentration, the remanent polarization and coercive electric field decrease, while the piezoelectric constant and the electromechanical coupling coefficient increase. The evolution of average and local structures as a function of temperature and composition was investigated using in-situ X-ray diffraction and Raman spectroscopy. The structure/property relationship of NBT-xKBT single crystals was discussed in detail.

Zhang, Haiwu; Chen, Chao; Zhao, Xiangyong; Deng, Hao; Ren, Bo; Li, Xiaobing; Luo, Haosu; Li, Shundao

2015-01-01

116

Piezoelectric Scanners  

NASA Astrophysics Data System (ADS)

Bimorph piezoelectric elements show relative large axial displacements at moderate voltages. Their response to voltage variations is very fast. The re-produceability of the displacement is practically limited only by the mechanical and electrical supplementary equipment. In combination with a deflection mirror linear scans or two-dimensional scan pattern can be generated. Fast scanning with good linearity and repeatability is possible, either in a resonant mode or in a random acces mode. However, the hysteresis of the piezoelectric material and the large capacitance of the elements impose some constraints on the applicability of the piezoelectric scanners. In the first part of the paper the properties of piezoelectric elements are discussed in view of scanner application; in the second part an experimental single mirror two-axis piezoelectric scanner is described. Some suggestions for future applications of piezoelectric scanners are made.

Hohner, M.; Manhart, S.

1987-09-01

117

Modeling Time-dependent Responses of Piezoelectric Fiber Composite  

E-print Network

. There are some lead-free piezoceramics such as sodium potassium niobate (KNN) and bismuth ferrite (BiFeO 3 ). Moreover, some polymers such as polyvinylidene fluoride (PVDF) and polyimide are also piezoelectric materials. The piezoelectric constant d of PVDF... varies between 1.5 to 32pC/N, which is much smaller than those of piezoelectric ceramics and the stiffness of PVDF is generally small, making it rather daunting for providing large actuation. PVDF is often used as sensor in smart composite. [1...

Li, Kuo-An

2011-02-22

118

Wettability of electroless Ni in the under bump metallurgy with lead free solder  

Microsoft Academic Search

This study investigates the wettability of several lead-free solders, including Sn, Sn?Ag, and Sn?Bi, on electroless Ni (EN)\\u000a with various phosphorus content. The role of phosphorus on solder wettability is studied. Microstructure evolution in the\\u000a lead-free solder\\/EN joint is investigated with the aid of electron probe microanalyzer (EPMA) to relate metallurgical reactions\\u000a between the solder and the EN. The SN

Bi-Lian Young; Jenq-Gong Duh; Bi-Shiou Chiou

2001-01-01

119

The Reliability Research of Lead-Free Solder Joint of Flip-Chip  

Microsoft Academic Search

Based on the minimum potential energy theorem and the theory of solder joint shape, 3D (three-dimensional) predicting model of flip-chip lead-free solder joints shape are established. According to different technologic parameters, the 3D solder joint shape is predicted. The nonlinear finite element analyses of the lead-free solder joint is performed by ANSYS under thermal cycles and the stress\\/strain distributions within

Yan De-jin; Zhou De-jian; Huang Chun-yue; Wu Zhao-hua; Zhou xiang

2006-01-01

120

Effects of PCB design variations on bend and ATC performance of lead-free solder joints  

Microsoft Academic Search

Sn-Ag-Cu (SAC) solder alloys, such as Sn-3.0Ag-0.5 Cu (SAC305) are the popular choices of lead-free solders replacing SnPb solders. However, SAC solders are more brittle in nature due to high stiffness and excessive intermetallic compounds growth at the solder joint to pad interface. This leads to higher risks in solder joints failures. Memory module type lead-free BGA packages are constantly

Hongtao Ma; Kuo-Chuan Liu; Tae-Kyu Lee; Dong Hyun Kim

2010-01-01

121

Lead-free hunting rifle ammunition: product availability, price, effectiveness, and role in global wildlife conservation.  

PubMed

Proposals to end the use of lead hunting ammunition because of the established risks of lead exposure to wildlife and humans are impeded by concerns about the availability, price, and effectiveness of substitutes. The product availability and retail prices of different calibers of lead-free bullets and center-fire rifle ammunition were assessed for ammunition sold in the USA and Europe. Lead-free bullets are made in 35 calibers and 51 rifle cartridge designations. Thirty-seven companies distribute internationally ammunition made with lead-free bullets. There is no major difference in the retail price of equivalent lead-free and lead-core ammunition for most popular calibers. Lead-free ammunition has set bench-mark standards for accuracy, lethality, and safety. Given the demonstrated wide product availability, comparable prices, and the effectiveness of high-quality lead-free ammunition, it is possible to phase out the use of lead hunting ammunition world-wide, based on progressive policy and enforceable legislation. PMID:23288616

Thomas, Vernon George

2013-10-01

122

Enhanced piezoelectric and mechanical properties of AlN-modified BaTiO3 composite ceramics.  

PubMed

BaTiO3-xAlN (BT-xAlN) composite ceramics were prepared by conventional solid state reaction sintering. The effects of the AlN content on the crystalline structures, densities, and electrical and mechanical properties of the BT ceramics were investigated. The BT-1.5%AlN ceramic exhibits a good piezoelectric constant of 305 pC N(-1) and an improved Vickers hardness of 5.9 GPa. The enhanced piezoelectricity originates from interactions between defect dipoles and spontaneous polarization inside the domains due to the occurrence of local symmetry, caused by the preferential distribution of the Al(3+)-N(3-) pairs vertical to the c axis. The hardening of the material is attributed to the improved density, and particle and grain boundary strengthening. Our work indicates that if a suitable doping ion pair is designed, lead-free ceramic systems prepared from ordinary raw materials by a conventional sintering method have a high probability of exhibiting good piezoelectric and mechanical properties simultaneously. PMID:24852079

Xu, Dan; Wang, Lidong; Li, Weili; Wang, Wei; Hou, Yafei; Cao, Wenping; Feng, Yu; Fei, Weidong

2014-07-14

123

Design and fabrication of lanthanum-doped tin-silver-copper lead-free solder for the next generation of microelectronics applications in severe environment  

NASA Astrophysics Data System (ADS)

Tin-Lead solder (Sn-Pb) has long been used in the Electronics industry. But, due to its toxic nature and environmental effects, certain restrictions are made on its use by the European Rehabilitation of Hazardous Substances (RoHS) directive, and therefore, many researchers are looking to replace it. The urgent need for removing lead from solder alloys led to the very fast introduction of lead-free solder alloys without a deep knowledge of their behavior. Therefore, an extensive knowledge and understanding of the mechanical behavior of the emerging generation of lead-free solders is required to satisfy the demands of structural reliability. Sn-Ag-Cu (SAC) solders are widely used as lead-free replacements but their coarse microstructure and formation of hard and brittle Inter-Metallic Compounds (IMCs) have limited their use in high temperature applications. Many additives are studied to refine the microstructure and improve the mechanical properties of SAC solders including iron (Fe), bismuth (Bi), antimony (Sb) and indium (In) etc. Whereas many researchers studied the impact of novel rare earth (RE) elements like lanthanum (La), cerium (Ce) and lutetium (Lu) on SAC solders. These RE elements are known as “vitamins of metals” because of their special surface active properties. They reduce the surface free energy, refine the grain size and improve the mechanical properties of many lead free solder alloys like Sn-Ag, Sn-Cu and SAC but still a systematic study is required to explore the special effects of “La” on the eutectic SAC alloys. The objective of this PhD thesis is to extend the current knowledge about lead free solders of SAC alloys towards lanthanum doping with varying environmental conditions implemented during service. This thesis is divided into six main parts.

Sadiq, Muhammad

124

Response of intergrown microstructure to an electric field and its consequences in the lead-free piezoelectric bismuth sodium titanate  

SciTech Connect

We investigate the R3c average structure and micro-structure of the ceramic Bi{sub 0.5}Na{sub 0.5}TiO{sub 3} (BNT) in situ under applied electric fields using diffraction techniques. Electron diffraction implies the presence of significant octahedral tilt twin disorder, corresponding to the existence of a fine scale intergrown microstructural (IGMS) 'phase' within the R3c rhombohedral average structure matrix. A careful neutron refinement suggests not only that the off-centre displacements of the cations relative to the oxygens in the R3c regions increases systematically on application of an electric field but also that the phase fraction of the IGMS regions increases systematically. The latter change in phase fraction on application of the electric field enhances the polar displacement of the cations relative to the oxygen anions and affects the overall strain response. These IGMS regions form local polar nano regions that are not correlated with one another, resulting in polarisation relaxation and strain behaviour observed in BNT-containing materials. - Graphical abstract: The intergrown microstructure at very fine scales within the R3c rhombohedral phase matrix of BNT, originating from octahedral tilt twinning disorder, will increase with respect to an external field. Highlights: Black-Right-Pointing-Pointer The existence of an intergrown microstructural 'phase' within the average structure matrix. Black-Right-Pointing-Pointer This phase fraction of the intergrown microstructural regions changes. Black-Right-Pointing-Pointer Such regions form local polar nano regions that are not correlated with one another.

Liu Yun, E-mail: yliu@rsc.anu.edu.au [Research School of Chemistry, Australian National University, ACT 0200 (Australia); Noren, Lasse [Research School of Chemistry, the Australian National University, ACT 0200 (Australia); Studer, Andrew J. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232 (Australia); Withers, Ray L.; Guo Yiping [Research School of Chemistry, Australian National University, ACT 0200 (Australia); Li Yongxiang [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Yang Hui [Research School of Chemistry, Australian National University, ACT 0200 (Australia); College of Life Science and Technology, Shaanxi University of Science and Technology, Xian 710021 (China); Wang Jian [Research School of Chemistry, Australian National University, ACT 0200 (Australia)

2012-03-15

125

Response of intergrown microstructure to an electric field and its consequences in the lead-free piezoelectric bismuth sodium titanate  

NASA Astrophysics Data System (ADS)

We investigate the R3c average structure and micro-structure of the ceramic Bi0.5Na0.5TiO3 (BNT) in situ under applied electric fields using diffraction techniques. Electron diffraction implies the presence of significant octahedral tilt twin disorder, corresponding to the existence of a fine scale intergrown microstructural (IGMS) 'phase' within the R3c rhombohedral average structure matrix. A careful neutron refinement suggests not only that the off-centre displacements of the cations relative to the oxygens in the R3c regions increases systematically on application of an electric field but also that the phase fraction of the IGMS regions increases systematically. The latter change in phase fraction on application of the electric field enhances the polar displacement of the cations relative to the oxygen anions and affects the overall strain response. These IGMS regions form local polar nano regions that are not correlated with one another, resulting in polarisation relaxation and strain behaviour observed in BNT-containing materials.

Liu, Yun; Norén, Lasse; Studer, Andrew J.; Withers, Ray L.; Guo, Yiping; Li, Yongxiang; Yang, Hui; Wang, Jian

2012-03-01

126

Effect of domain structure on the mechanical and piezoelectric properties of lead-free alkali niobate ceramics  

NASA Astrophysics Data System (ADS)

Load-bearing applications, such as actuators, require sufficient mechanical properties to guarantee long lifetime and reliability. Lead zirconate titanate (PZT) ceramics show relatively low mechanical strength which decreases after applying an electric field. Thus far, evaluations of the mechanical properties have not been the focus in the case of alkali niobate-based (NKN) ceramics. For this purpose, differently poled Lix(Na0.5K0.5)1-xNbO3 ceramics have been observed by means of 3-point bending tests. Best results were achieved with Li0.02Na0.49K0.49NbO3, with a flexural strength of 115 MPa in unpoled state. This value was maximized at a 90° domain switching fraction ? of about 20% to 134 MPa. Other compositions showed similar behavior, which led to the idea that domain switching can be used to enhance the mechanical properties of NKN ceramics. Internal stresses induced via domain reorientation might be the cause of this phenomenon and will be examined in this study.

Martin, Alexander; Kakimoto, Ken-ichi

2014-09-01

127

Performance of Lead-Free versus Lead-Based Hunting Ammunition in Ballistic Soap  

PubMed Central

Background Lead-free hunting bullets are an alternative to lead-containing bullets which cause health risks for humans and endangered scavenging raptors through lead ingestion. However, doubts concerning the effectiveness of lead-free hunting bullets hinder the wide-spread acceptance in the hunting and wildlife management community. Methods We performed terminal ballistic experiments under standardized conditions with ballistic soap as surrogate for game animal tissue to characterize dimensionally stable, partially fragmenting, and deforming lead-free bullets and one commonly used lead-containing bullet. The permanent cavities created in soap blocks are used as a measure for the potential wound damage. The soap blocks were imaged using computed tomography to assess the volume and shape of the cavity and the number of fragments. Shots were performed at different impact speeds, covering a realistic shooting range. Using 3D image segmentation, cavity volume, metal fragment count, deflection angle, and depth of maximum damage were determined. Shots were repeated to investigate the reproducibility of ballistic soap experiments. Results All bullets showed an increasing cavity volume with increasing deposited energy. The dimensionally stable and fragmenting lead-free bullets achieved a constant conversion ratio while the deforming copper and lead-containing bullets showed a ratio, which increases linearly with the total deposited energy. The lead-containing bullet created hundreds of fragments and significantly more fragments than the lead-free bullets. The deflection angle was significantly higher for the dimensionally stable bullet due to its tumbling behavior and was similarly low for the other bullets. The deforming bullets achieved higher reproducibility than the fragmenting and dimensionally stable bullets. Conclusion The deforming lead-free bullet closely resembled the deforming lead-containing bullet in terms of energy conversion, deflection angle, cavity shape, and reproducibility, showing that similar terminal ballistic behavior can be achieved. Furthermore, the volumetric image processing allowed superior analysis compared to methods that involve cutting of the soap blocks. PMID:25029572

Gremse, Felix; Krone, Oliver; Thamm, Mirko; Kiessling, Fabian; Tolba, René Hany; Rieger, Siegfried; Gremse, Carl

2014-01-01

128

Assembly of lead-free bumped flip-chip with no-flow underfills  

Microsoft Academic Search

Lead-free solder reflow process has presented challenges to no-flow underfill material and assembly. The currently available no-flow underfill materials are mainly designed for eutectic Sn-Pb solders. This paper presents the assembly of lead-free bumped flip-chip with developed no-flow underfill materials. Epoxy resin\\/HMPA\\/metal AcAc\\/Flux G system is developed as no-flow underfills for Sn\\/Ag\\/Cu alloy bumped flip-chips. The solder wetting test is

Zhuqing Zhang; C. P. Wong

2002-01-01

129

Structure and temperature dependent electrical properties of lead-free Bi0.5Na0.5TiO3- SrZrO3 ceramics  

NASA Astrophysics Data System (ADS)

Lead-free SrZrO3-modified Bi0.5Na0.5TiO3 (BNT-SZ) ceramics were fabricated by a conventional solid state reaction method. X-ray diffraction analysis reveals a pure perovskite phase without any traces of secondary phases. Scanning electron microscopy images depicts dense grain morphology. The temperature dependences of the dielectric behavior was measured in the temperature range of 50-500 °C at 100 kHz. With the increase in SZ content, the dielectric constant (?r) constantly decreased and the maximum dielectric constant temperature (Tm) shifted towards lower temperatures. In addition to this, ferroelectric hysteresis loops indicated a disruption of ferroelectric order and increase in the relaxor character of BNT ceramics with increase in SZ concentration. A maximum values of remnant polarization (32 ?C/cm2) and piezoelectric constant (100 pC/N) were observed at SZ5 and SZ4, respectively.

Maqbool, Adnan; Rahman, Jamil ur; Hussain, Ali; Park, Jong Kyu; Gone Park, Tae; Song, Jae Sung; Kim, Myong Ho

2014-06-01

130

Characteristics of Acoustic Emission Sensor Using Lead-Free (LiNaK)(NaTaSb)O3 Ceramics for Fluid Leak Detection at Power Plant Valves  

NASA Astrophysics Data System (ADS)

In this study, acoustic emission (AE) sensor was fabricated using lead-free (LiNaK)-(NbTaSb)O3 ceramics for preventing environmental pollution. The structure of the AE sensor was designed as a Langevin-type one with air backing. The electromechanical coupling factor kp and piezoelectric constants d33 and g33 of lead-free (LiNaK)-(NbTaSb)O3 ceramics were 0.49, 300 pC/N, 27.02 mV·m/N, respectively. The peak sensitivity and frequency of the AE sensor using this ceramic material were 66.3 dB and 29.4 kHz, respectively. The results for fluid leak detection at a power plant valve were as follows; the peak frequency of response was 25 kHz at 2 and 6 kgf/cm2 N2 gas pressures, and increased up to 50 kHz at a 10 kgf/cm2 N2 gas pressure. The magnitude of the response voltage was about 40 mV at all the pressures.

Hong, Jaeil; Yoo, Juhyun; Lee, Kabsoo; Lee, Sangguk; Song, Hyunseon

2008-04-01

131

Fracture Behavior and Characterization of Lead-Free Brass Alloys for Machining Applications  

NASA Astrophysics Data System (ADS)

The stricter environmental, health, and safety regulations address the harmful effects of lead and provide the driving force for the development of lead-free brass alloys. Conventional leaded brass rods are widely used in several manufacturing sectors (i.e., fabrication of hydraulic components, fittings, valves, etc.) due to their superior workability in extrusion and drawing as well as their superior machinability. As machinability performance involves shear and dynamic fracture processes evolved under high strain-rate conditions, the understanding of the mechanical behavior/microstructure interaction is critical in order to successfully tailor candidate lead-free alloys for improved machinability without compromising the reliability of manufactured components. In this work, the mechanical behavior under static and dynamic loading of three lead-free brass alloys (CW510L-CW511L-C27450) in comparison to a conventional leaded brass alloy (CW614N) was studied. The fractographic evaluation of the texture of conjugate fracture surfaces was performed to identify the involved fracture mechanisms and their relation to the alloy microstructure. It was shown that the CW510L lead-free brass alloy is a potential candidate in replacing conventional CW614N leaded brass, combining high tensile strength and fracture toughness, due to the prevalence of the ?-intermetallic phase in the alloy microstructure.

Toulfatzis, Anagnostis I.; Pantazopoulos, George A.; Paipetis, Alkiviadis S.

2014-09-01

132

How to Identify Lead-Free Certification Marks for Drinking Water System & Plumbing Materials - Presentation  

EPA Science Inventory

In 2011, Congress passed the ?Reduction of Lead in Drinking Water Act,? which effectively reduces the lead content allowed in material used for potable water plumbing. The Act, which will go into effect on January 4, 2014, changes the definition of ?lead-free? by reducing allowed...

133

Lead-free halide perovskite solar cells with high photocurrents realized through vacancy modulation.  

PubMed

Lead free perovskite solar cells based on a CsSnI3 light absorber with a spectral response from 950 nm is demonstrated. The high photocurrents noted in the system are a consequence of SnF2 addition which reduces defect concentrations and hence the background charge carrier density. PMID:25212785

Kumar, Mulmudi Hemant; Dharani, Sabba; Leong, Wei Lin; Boix, Pablo P; Prabhakar, Rajiv Ramanujam; Baikie, Tom; Shi, Chen; Ding, Hong; Ramesh, Ramamoorthy; Asta, Mark; Graetzel, Michael; Mhaisalkar, Subodh G; Mathews, Nripan

2014-11-01

134

Joint Lead-Free Solder Test Program for High Reliability Military and Space Applications  

NASA Technical Reports Server (NTRS)

Current and future space and defense systems face potential risks from the continued use of tin-lead solder, including: compliance with current environmental regulations, concerns about potential environmental legislation banning lead-containing products, reduced mission readiness, and component obsolescence with lead surface finishes. For example, the United States Environmental Protection Agency (USEPA) has lowered the Toxic Chemical Release reporting threshold for lead to 100 pounds. Overseas, the Waste Electrical and Electronic Equipment (WEEE) and the Restriction on Hazardous Substances (RoHS) Dicctives in Europe and similar mandates in Japan have instilled concern that a legislative body will prohibit the use of lead in aerospace/military electronics soldering. Any potential banning of lead compounds could reduce the supplier base and adversely affect the readiness of missions led by the National Aeronautics and Space Administration (NASA) and the U.S. Department of Defense (DoD). Before considering lead-free electronics for system upgrades or future designs, however, it is important for the DoD and NASA to know whether lead-free solders can meet their systems' requirements. No single lead-free solder is likely to qualify for all defense and space applications. Therefore, it is important to validate alternative solders for discrete applications. As a result of the need for comprehensive test data on the reliability of lead-free solders, a partnership was formed between the DoD, NASA, and several original equipment manufactures (OEMs) to conduct solder-joint reliability (laboratory) testing of three lead-free solder alloys on newly manufactured and reworked circuit cards to generate performance data for high-reliability (IPC Class 3) applications.

Brown, Christina

2004-01-01

135

Piezoelectric transducer  

NASA Technical Reports Server (NTRS)

Transducer consists of a hybrid thin film and a piezoelectric transistor that acts as a stress-sensitive device with built-in gain. It provides a stress/strain transducer that incorporates a signal amplification stage and sensor in a single package.

Conragan, J.; Muller, R. S.

1970-01-01

136

Stable resonance characteristics in CuO-modified lead-free 0.94(K0.5Na0.5)NbO3-0.06LiNbO3 ceramics sintered at optimal temperature  

Microsoft Academic Search

Lead-free piezoelectric ceramics with the nominal composition of [(K0.5Na0.5)0.94Li0.06]NbO3+xmol%CuO [KNLN+ xmol%CuO] had been synthesized by conventional solid-state sintering. Effects of the addition of CuO on the phase structure, micro-morphology evolution and electric properties of the ceramics were investigated. The ceramics synthesized at 1000-1060 degC showed a phase transition from orthorhombic to tetragonal symmetry, which is analogous to the morphtropic phase

Dandan Wan; Ying Yang; Qian Li; Kongjun Zhu

2008-01-01

137

Strain rate effect and Johnson-Cook models of lead-free solder alloys  

Microsoft Academic Search

Drop\\/impact causes high strain rate deformation in solder joints of microelectronics package. It is important to understand mechanical behavior of solder joints under high strain rate for reliability design of products. In this paper mechanical behaviors of two lead-free solder alloys, Sn3.5Ag and Sn3.0Ag0.5Cu, were investigated by quasi-static tests and the split Hopkinson tension\\/pressure bar testing technique under high strain

Qin Fei; An Tong; Chen Na

2008-01-01

138

NASA-DoD Lead-Free Electronics Project: Vibration Test  

NASA Technical Reports Server (NTRS)

Vibration testing was conducted by Boeing Research and Technology (Seattle) for the NASA-DoD Lead-Free Electronics Solder Project. This project is a follow-on to the Joint Council on Aging Aircraft/Joint Group on Pollution Prevention (JCAA/JG-PP) Lead-Free Solder Project which was the first group to test the reliability of lead-free solder joints against the requirements of the aerospace/miLItary community. Twenty seven test vehicles were subjected to the vibration test conditions (in two batches). The random vibration Power Spectral Density (PSD) input was increased during the test every 60 minutes in an effort to fail as many components as possible within the time allotted for the test. The solder joints on the components were electrically monitored using event detectors and any solder joint failures were recorded on a Labview-based data collection system. The number of test minutes required to fail a given component attached with SnPb solder was then compared to the number of test minutes required to fail the same component attached with lead-free solder. A complete modal analysis was conducted on one test vehicle using a laser vibrometer system which measured velocities, accelerations, and displacements at one . hundred points. The laser vibrometer data was used to determine the frequencies of the major modes of the test vehicle and the shapes of the modes. In addition, laser vibrometer data collected during the vibration test was used to calculate the strains generated by the first mode (using custom software). After completion of the testing, all of the test vehicles were visually inspected and cross sections were made. Broken component leads and other unwanted failure modes were documented.

Woodrow, Thomas A.

2010-01-01

139

Impression creep testing and microstructurally adaptive creep modeling of lead free solder interconnects  

Microsoft Academic Search

Creep plays an important role in the reliability of solder joints under thermo-mechanical fatigue conditions encountered by a microelectronic package during service. In addition, the fine intermetallic precipitates (Ag3Sn and\\/or Cu6Sn5) in the microstructures of the new lead-free solders (Sn-Ag and Sn-Ag-Cu) can undergo significant in situ strain-enhanced coarsening during TMC, resulting in in-service evolution of the creep behavior of

I. Dutta; D. Pan; S. Jadhav

2005-01-01

140

Low temperature electromigration and thermomigration in lead-free solder joints  

Microsoft Academic Search

High current density and high temperature gradient are major reliability concern for next generation nanoelectronic packaging and power electronics. High current density experiments on lead free solder joints coated with NiAu and non-coated Cu pads were conducted at ?20, ?30, ?40 and ?50°C ambient temperatures. The time to failure (TTF) shows that solder joints with NiAu coated Cu pads last

Cemal Basaran; Mohd F. Abdulhamid

2009-01-01

141

Piezoelectric Effect  

NSDL National Science Digital Library

In this activity, by the Concord Consortium's Molecular Literacy project, students explore the piezoelectric effect, which is the conversion between electricity and mechanical motion. The model used in this activity shows this conversion and users can manipulate the model to change the voltage and observe changes to a crystal. The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In these activities, students are allowed to explore at their own pace in a digital environment full of demonstrations, illustrations, and models they can manipulate. In addition to the activity, visitors will find an overview of the activity and central and key concepts.

2008-10-23

142

Lead-Free Double-Base Propellant for the 2.75 Inch Rocket Motor  

NASA Technical Reports Server (NTRS)

The current MK 66 2.75 inch Rocket Motor double-base propellant contains the lead-based ballistic modifier LC-12-15 to achieve the desired plateau and mesa burning rate characteristics. The use of lead compounds poses a concern for the environment and for personal safety due to the metal's toxic nature when introduced into the atmosphere by propellant manufacture, rocket motor firing, and disposal. Copper beta-resorcylate (copper 2,4-di-hydroxy-benzoate) was successfully used in propellant as a simple modifier in the mid 1970's. This and other compounds have also been mixed with lead salts to obtain more beneficial ballistic results. Synthesized complexes of lead and copper compounds soon replaced the mixtures. The complexes incorporate the lead, copper lack of organic liquids, which allows for easier propellant processing. About ten years ago, the Indian Head Division, Naval Surface Warfare Center (NSWC), initiated an effort to develop a lead-free propellant for use in missile systems. Several lead-free propellant candidate formulations were developed. About five years ago, NSWC, in conjunction with Alliant Techsystems, Radford Army Ammunition Plant, continued ballistic modifier investigations. A four component ballistic modifier system without lead for double-base propellants that provide adequate plateau and mesa burn rate characteristics was developed and patented. The ballistic modifier's system contains bismuth subsalicylate, 1.5 percent; copper salicylate, 1.0 percent, copper stannate, 0.77 percent; and carbon black, 0.1 percent. Action time and impulse data obtained through multiple static firings indicate that the new lead-free double-base propellant, while not a match for NOSIH-AA-2, will be a very suitable replacement in the 2.75 inch Rocket Motor. Accelerated aging of the double-base propellant containing the lead-free ballistic modifier showed that it had a much higher rate of stabilizer depletion than the AA-2. A comprehensive study showed that an increased rate of stabilizer depletion occurred in propellants containing monobasic copper salicylate. The study also showed that propellants containing a mixture of bismuth subsalicylate and copper salicylate, had only about one-half the stabilizer depletion rate than those with copper salicylate alone. The copper salicylate catalyzes the decomposition of nitroglycerin, which triggers a chain of events leading to the increased rate of stabilizer depletion. A program has been initiated to coat the ballistic modifier, thus isolating it from the nitroglycerin.

Magill, B. T.; Nauflett, G. W.; Furrow, K. W.

2000-01-01

143

Lead-free ferroelectric relaxor ceramics derived from BaTiO_3  

NASA Astrophysics Data System (ADS)

A large number of lead-free BaTiO3-based ceramics were prepared. Depending on the composition, some of them exhibit a relaxor behaviour whose characteristics were related to the type of ionic substitution and to the substitution rate. The relaxor effect is all the more favoured as the composition deviates more from BaTiO3 and as the substitution is heterovalent in the 6-coordination number crystallographic site. Some of these materials could prove valuable (dielectrics for capacitors and actuators) because they are environment-friendly.

Ravez, J.; Simon, A.

2000-07-01

144

Developing a self-diagnostic system for piezoelectric sensors  

NASA Technical Reports Server (NTRS)

Measurement techniques for developing a self-diagnostic system for piezoelectric sensors are presented. The self-diagnostic system uses two types of measurement techniques based on passive and active evaluation of the piezoelectric element. Both hard and soft failures can be detected by this system. Hard failures such as loss of sensor signal and change in sensor output resistance are determined by monitoring the sensor's output resistance, voltage or current. These are passive measurements of the sensor's output condition. Soft failures include changes in sensor calibration and mounting conditions. Soft failures are detected by measuring structural/electrical impedance of the piezoelectric sensor. Active measurement techniques are used to calculate changes in piezoelectric element properties related to soft failures. This paper describes the general operating principles of a self-diagnostic system and discusses the design of an active/passive measurement technique required for this system to function. Experimental results using two types of piezoelectric accelerometers are presented.

Flanagan, Patrick M.; Atherton, William J.

1990-01-01

145

Tin pest in Sn-0.5 wt.% Cu lead-free solder  

NASA Astrophysics Data System (ADS)

Tin pest (the product of the allotropic transformation of ?-tin into ?-tin at temperatures below 286 K) has been observed in a Sn-0.5 wt.% Cu solder alloy. Some 40 percent of the specimen surface was transformed into gray tin after aging at 255K for 1.5 years, and after 1.8 years, the proportion increased to about 70 percent. The degree of transformation in work-hardened areas is much higher than in other areas, suggesting residual stress might provide an additional driving force for the transformation into ?-tin. The allotropic change results in a 26 percent increase in volume, and cracks are initiated to accommodate the changes in volume. Results indicate that tin pest could lead to total disintegration of micro-electronic solder joints. The tin-copper eutectic system may become a prominent lead-free solder, and tin pest could have major ramifications on service lifetime of electronic assemblies.

Kariya, Yoshiharu; Williams, Naomi; Gagg, Colin; Plumbridge, William

2001-06-01

146

Analysis of lead free tin-silver-copper and tin-lead solder wetting reactions  

NASA Astrophysics Data System (ADS)

Lead free electronics soldering is driven by a combination of health and environmental concerns, international legislation and marketing pressure by lead free electronics manufacturing competitors. Since July 1, 2006, companies that do not comply with the European Union legislation are not able to sell circuit assemblies with lead solder in the European Union. China has developed its own regulations, based on the European Union documents with a compliance date of March 1, 2007. Extensive testing by the electronics community has determined that the Sn - Ag - Cu (SAC) family of alloys is the preferred choice for lead free Surface Mount Technology (SMT) soldering. The 96.5Sn/3.0Ag/0.5Cu alloy was used in this study. Lead free soldering requires an increase in reflow peak temperatures which further aggravates component moisture sensitivity risks and thereby decreases assembly yield. Prior research has revealed an enhanced solder spreading phenomena at lower peak temperature and shorter time above liquidus with 63Sn/37Pb solder. This current research investigated solder wetting reactions in 63Sn/37Pb and 96.5Sn/3.0Ag/0.5Cu (SAC305) using materials and manufacturing systems that are industry relevant. The objective was to advance the knowledge base of metal wetting while developing a reflow assembly process that minimized the component defect rates. The components are damaged during reflow by popcorn delamination, which is the result of moisture absorption and subsequent rapid evaporation. A classical Design Of Experiments (DOE) approach was used, with wetted area as the response variable. Outside of the DOE, substrate dissolution depth, and substrate surface new phase formation (reaction product) distance from the triple line (solder wetting front) and reaction product thickness in the solder joint (under the solder) were also analyzed. The samples were analyzed for correlation of reflow peak temperature, reflow Time Above Liquidus (TAL), wetted area, reaction product distance from the triple line, substrate dissolution depth, triple line ridge (substrate protrusion into the molten solder) formation and reaction product thickness in the solder joint. The general results are (1) an improved understanding of 63Sn/37Pb and 96.5Sn/3.0Ag/0.5Cu WT% solder wetting reactions, (2) reduced 63Sn/37Pb and SAC reflow peak temperatures, and thereby reduced risk of moisture sensitivity damage to components. The significance of these results are (1) enhanced applied understanding of the complexity of molten metal wetting a substrate and (2) enhanced assembly yield due to minimal aggravation of component moisture sensitivity. The uniqueness of this research is that it utilized a holistic Systems Science approach which provided a combined microscopic (substrate and molten metal reactions) and macroscopic (wetted area) analysis of metal wetting using materials and processes that were directly relevant to electronics manufacturing.

Anson, Scott J.

147

KNN/BNT Composite Lead-Free Films for High-Frequency Ultrasonic Transducer Applications  

PubMed Central

Lead-free K0.5Na0.5NbO3/Bi0.5Na0.5TiO3 (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-?m-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. PMID:21244994

Lau, Sien Ting; Ji, Hong Fen; Li, Xiang; Ren, Wei; Zhou, Qifa; Shung, K. Kirk

2011-01-01

148

Integration of lead-free ferroelectric on HfO2/Si (100) for high performance non-volatile memory applications.  

PubMed

We introduce a novel lead-free ferroelectric thin film (1-x)BaTiO3-xBa(Cu1/3Nb2/3)O3 (x = 0.025) (BT-BCN) integrated on to HfO2 buffered Si for non-volatile memory (NVM) applications. Piezoelectric force microscopy (PFM), x-ray diffraction, and high resolution transmission electron microscopy were employed to establish the ferroelectricity in BT-BCN thin films. PFM study reveals that the domains reversal occurs with 180° phase change by applying external voltage, demonstrating its effectiveness for NVM device applications. X-ray photoelectron microscopy was used to investigate the band alignments between atomic layer deposited HfO2 and pulsed laser deposited BT-BCN films. Programming and erasing operations were explained on the basis of band-alignments. The structure offers large memory window, low leakage current, and high and low capacitance values that were easily distinguishable even after ~10(6)?s, indicating strong charge storage potential. This study explains a new approach towards the realization of ferroelectric based memory devices integrated on Si platform and also opens up a new possibility to embed the system within current complementary metal-oxide-semiconductor processing technology. PMID:25683062

Kundu, Souvik; Maurya, Deepam; Clavel, Michael; Zhou, Yuan; Halder, Nripendra N; Hudait, Mantu K; Banerji, Pallab; Priya, Shashank

2015-01-01

149

Piezoelectric Ultrasonic Micromotors  

E-print Network

This report describes development of micro-fabricated piezoelectric ultrasonic motors and bulk-ceramic piezoelectric ultrasonic motors. Ultrasonic motors offer the advantage of low speed, high torque operation without ...

Flynn, Anita M.

1995-06-01

150

On the research of lead-free material challengers for PZT replacement  

NASA Astrophysics Data System (ADS)

This paper reports a study of Ba0.9Sr0.1TiO3 and BaTi0.98Sn0.02O3 thin films elaborated by a sol-gel route and deposited on Pt/Ti/SiO2/Si substrates. The annealing temperatures were 750 °C, 850 °C and 950 °C. An increase of the average size of grains was observed, from 60 nm at 750 °C to 110 nm at 950 °C and from 70 nm at 750 °C to 150 nm at 950 °C, for BST and BTS respectively, as well as an increase of the dielectric constant and remnant polarization. We have also shown that there are benefits for electrical properties to decrease the annealing time. Despite its non-significant piezoelectric and ferroelectric properties, BTS gives good dielectric properties. Under our optimized annealing conditions, we gave the evidence that ferroelectric BST is a good challenger to replace PZT in various applications, except in piezoelectrics, as the electrical properties measured on our thin films were particularly significant for applications in electronic devices.

Fasquelle, D.; Mascot, M.; Carru, J. C.

2012-09-01

151

Piezoelectric drive circuit  

DOEpatents

A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes.

Treu, Jr., Charles A. (Raymore, MO)

1999-08-31

152

Piezoelectrically Assisted Ultrafiltration  

Microsoft Academic Search

We have demonstrated the feasibility of using piezoelectrically assisted ultrafiltration to reduce membrane fouling and enhance the flux through ultrafiltration membranes. A preliminary economic evaluation, accounting for the power consumption of the piezoelectric driver and the extent of permeate flow rate enhancement, has also shown that piezoelectrically assisted ultrafiltration is cost effective and economically competitive in comparison with traditional separation

N. Ahner; D. Gottschlich; S. Narang; D. Roberts; S. Sharma; S. Ventura

1993-01-01

153

"Mighty Worm" Piezoelectric Actuator  

NASA Technical Reports Server (NTRS)

"Mighty Worm" piezoelectric actuator used as adjustable-length structural member, active vibrator or vibration suppressor, and acts as simple (fixed-length) structural member when inactive. Load force not applied to piezoelectric element in simple-structural-member mode. Piezoelectric element removed from load path when not in use.

Bamford, Robert M.; Wada, Ben K.; Moore, Donald M.

1994-01-01

154

Dielectric properties of lead-free BZT-KNN perovskite ceramics for energy storage.  

PubMed

Lead-free (1-x)Ba(Zr?.??Ti?.??)O?-x(K?.?Na?.?)NbO? ; x=0-0.05) (BZT-KNN) perovskite ceramics, a materials with potential applications for energy storage, are investigated. The samples are prepared by a solid-state reaction method. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to study the microstructure of the samples. Their dielectric properties and impedance spectra are reported as functions of temperature and frequency. The addition of 1?mol?% (K?.?Na?.?)NbO? to Ba(Zr?.??Ti?.??)O? improves the dielectric constant and enhances its diffuseness in a wide temperature range. The small amount of (K?.?Na?.?)NbO? is found to markedly affect the microstructure of the Ba(Zr?.??Ti?.??)O? ceramic (grain size and other characteristics) without changing the phase or crystal symmetry. In addition, we report that fine substructures in the grains, so-called sheet structures, are responsible for the dielectric properties (both diffuseness and dielectric constant) of (1-x)Ba(Zr?.??Ti?.??)O?-x(K?.?Na?.?)NbO? (x=0-0.03; especially x=0.01) ceramics. PMID:21994154

Gui, Dong-Yun; Liu, Han-Xing; Hao, Hua; Sun, Yue; Cao, Ming-He; Yu, Zhi-Yong

2011-10-17

155

Development of extremely ductile lead-free Sn-Al solders for futuristic electronic packaging applications  

NASA Astrophysics Data System (ADS)

In the present study, new lead-free Sn-Al solders are developed incorporating varying amount of Al (0.4 and 0.6% by weight) into pure Sn using disintegrated melt deposition technique. Solder samples were then subsequently extruded at room temperature and characterized. Microstructural characterization studies revealed equiaxed grain morphology, minimal porosity, reasonably uniform distribution of Al particles and good Sn-Al interfacial integrity. Melting temperature of Sn-0.6Al (228°C) was found to be close to the eutectic Sn-0.7Cu (227°C) solders. Microhardness was increased with increasing amount of Al in pure Sn. Room temperature tensile test results revealed that newly developed Sn-0.6Al solders exhibited significant improvement in 0.2% yield strength (˜67%), ultimate tensile strength (˜18%) and ductility (˜123%) when compared to commercial Sn-0.7Cu solder. Ductility was improved about 222%, 263% and 81% when compared to commercially available Sn-3.5Ag-0.7Cu, Sn-3.5Ag and Sn-37Pb solders, respectively without compromising strength.

Alam, Md Ershadul; Gupta, Manoj

2014-03-01

156

In Situ Synchrotron Characterization of Melting, Dissolution, and Resolidification in Lead-Free  

SciTech Connect

Melting and solidification of SAC 305 lead-free solder joints in a wafer-level chip-scale package were examined in situ with synchrotron x-ray diffraction. The chips with balls attached (but not assembled to a circuit board) were reflowed one to three times using a temperature and time history similar to an industrial reflow process. Diffraction patterns from the same joint were collected every 0.5 s during the melting and solidification process. The solidification of the Sn phase in the solder joint occurred between 0.5 s and 1 s. During melting, most of the Sn melted in about 0.5 s, but in some cases took 2-5 s for the Sn peak to completely disappear. In one instance, the Sn peak persisted for 30 s. The Ag{sub 3}Sn peaks dissolved in about 1-2 s, but the Cu{sub 6}Sn{sub 5} peaks from the interface were persistent and did not change throughout the melting and solidification process. Completely different Sn crystal orientations were always developed upon resolidification.

Zhou, Bite; Bieler, Thomas R.; Wu, Guilin; Zaefferer, Stefan; Lee, Tae-Kyu; Liu, Kuo-Chuan (Michigan); (Cisco); (MXPL)

2013-04-08

157

SHPB tests for mechanical behavior of lead-free solder alloys  

NASA Astrophysics Data System (ADS)

Dynamic behavior of solder joints in microelectronic packages is key issue for drop/impact reliability design of mobile electronic products. The dynamic mechanical behavior of 63Sn37Pb, 96.5Sn3.5Ag and 96.5Sn3.0Ag0.5Cu at high strain rates have been investigated by using the split Hopkinson pressure/tension bar testing technique (SHPB). Stress-strain relations of the three solders were obtained at strain rates of 600s-1, 1200s-1 and 2200s-1, respectively. The experimental results show that the lead-free solders are strongly strain rate dependent. 96.5Sn3.5Ag is the most sensitive to strain rate, while 63Sn37Pb is the least. 96.5Sn3.0Ag0.5Cu has the greatest yield stress and tensile strength. Relations of the yield stress and the tensile strength of the solders with strain rate were fitted.

Qin, Fei; An, Tong; Chen, Na

2008-11-01

158

Mechanical Properties of Lead-Free Solder Joints Under High-Speed Shear Impact Loading  

NASA Astrophysics Data System (ADS)

In this study we expanded on recently reported research by using a modified miniature Charpy impact-testing system to investigate the shear deformation behavior of Sn-3.0Ag-0.5Cu lead-free solder joints at high strain rates ranging from 1.1 × 103 s-1 to 5.5 × 103 s-1. The experimental results revealed that the maximum shear strength of the solder joint decreased with increasing load speed in the ranges tested in this study. For solder joints tested at a shear speed exceeding 1 m/s, corresponding to an approximate strain rate that exceeds 1950 s-1, the brittle fracture mode is the main failure mode, whereas lower strain rates result in a ductile-to-brittle transition in the fracture surfaces of solder joints. In addition, the mode II stress intensity factor ( K II) used to evaluate the fracture toughness ( K C) of an interfacial intermetallic compound layer between Sn-3.0Ag-0.5Cu solder and the toughness of copper substrate was found to decrease from 1.63 MPa m0.5 to 0.97 MPa m0.5 in the speed range tested here.

Nguyen, Van Luong; Kim, Ho-Kyung

2014-11-01

159

Mechanical Properties of Lead-Free Solder Joints Under High-Speed Shear Impact Loading  

NASA Astrophysics Data System (ADS)

In this study we expanded on recently reported research by using a modified miniature Charpy impact-testing system to investigate the shear deformation behavior of Sn-3.0Ag-0.5Cu lead-free solder joints at high strain rates ranging from 1.1 × 103 s-1 to 5.5 × 103 s-1. The experimental results revealed that the maximum shear strength of the solder joint decreased with increasing load speed in the ranges tested in this study. For solder joints tested at a shear speed exceeding 1 m/s, corresponding to an approximate strain rate that exceeds 1950 s-1, the brittle fracture mode is the main failure mode, whereas lower strain rates result in a ductile-to-brittle transition in the fracture surfaces of solder joints. In addition, the mode II stress intensity factor (K II) used to evaluate the fracture toughness (K C) of an interfacial intermetallic compound layer between Sn-3.0Ag-0.5Cu solder and the toughness of copper substrate was found to decrease from 1.63 MPa m0.5 to 0.97 MPa m0.5 in the speed range tested here.

Nguyen, Van Luong; Kim, Ho-Kyung

2014-09-01

160

Developing a NASA Lead-Free Policy for Electronics - Lessons Learned  

NASA Technical Reports Server (NTRS)

The National Aeronautics and Space Administration (NASA) is not required by United States or international law to use lead-free (Pb-free) electronic systems but international pressure in the world market is making it increasingly important that NASA have a Pb-free policy. In fact, given the international nature of the electronics market, all organizations need a Pb-free policy. This paper describes the factors which must be taken into account in formulating the policy, the tools to aid in structuring the policy and the unanticipated and difficult challenges encountered. NASA is participating in a number of forums and teams trying to develop effective approaches to controlling Pb-free adoption in high reliability systems. The activities and status of the work being done by these teams will be described. NASA also continues to gather information on metal whiskers, particularly tin based, and some recent examples will be shared. The current lack of a policy is resulting in "surprises" and the need to disposition undesirable conditions on a case-by-case basis. This is inefficient, costly and can result in sub-optimum outcomes.

Sampson, Michael J.

2008-01-01

161

On the Future of Head-Based Microactuators in Hard Disk Drives  

E-print Network

ferroelectric   polarization  vector   P   3.4.1          Transverse  Mode  (d 31 )  Piezoelectric  Actuator            Actuator   and   Its   Reliability   for   Hard   Disk   Drives,   IEEE  Trans.  on  Ultrasonics,   Ferroelectrics,  and  

Wernow, Josiah Natan

2012-01-01

162

10 ?? 10 cm2 Hit Solar Cells Contacted with Lead-Free Electrical Conductive Adhesives to Solar Cell Interconnectors  

Microsoft Academic Search

In the present study we have investigated the optical and electrical properties of 10 ?? 10 cm2 HIT solar cells with evaporated Cr\\/Ag grids. Contacts were done with low temperature lead-free electrically conductive adhesives to standard solar cell interconnector tabs (IT). Compared to solder joints conductive adhesives have the advantage of lower contact formation temperature with reasonable low contact resistances

M. L. D. Scherff; S. Schwertheim; Yue Ma; T. Mueller; W. R. Fahrner

2006-01-01

163

NEW LEAD-FREE PEROVSKITE RELAXOR CERAMICS DERIVED FROM BaTiO3 AND CONTAINING SCANDIUM  

E-print Network

NEW LEAD-FREE PEROVSKITE RELAXOR CERAMICS DERIVED FROM BaTiO3 AND CONTAINING SCANDIUM ANNIE SIMON-ray diffraction and dielectric characterizations. Dielectric measurements performed on ceramics with 0 x 0 therefore been performed in detail on ceramics with BaTiO3-derived compositions.2-23 Thanks to frequency

Boyer, Edmond

164

A piezoelectric transformer  

NASA Technical Reports Server (NTRS)

This work describes a modeling and design method whereby a piezoelectric system is formulated by two sets of second-order equations, one for the mechanical system, and the other for the electrical system, coupled through the piezoelectric effect. The solution to this electromechanical coupled system gives a physical interpretation of the piezoelectric effect as a piezoelectric transformer that is a part of the piezoelectric system, which transfers the applied mechanical force into a force-controlled current source, and short circuit mechanical compliance into capacitance. It also transfers the voltage source into a voltage-controlled relative velocity input, and free motional capacitance into mechanical compliance. The formulation and interpretation simplify the modeling of smart structures and lead to physical insight that aids the designer. Due to its physical realization, the smart structural system can be unconditional stable and effectively control responses. This new concept has been demonstrated in three numerical examples for a simple piezoelectric system.

Won, C. C.

1993-01-01

165

Domain-orientation-controlled potassium niobate family piezoelectric materials with hydrothermal powders.  

PubMed

Materials of the potassium niobate family, as lead-free piezoelectric materials, are expected to be alternative materials to Pb(Zr,Ti)O3 (PZT) because of their good piezoelectric properties, high Curie temperature, and so on. In particular, single-crystal potassium niobate is a promising ferroelectric material as a surface acoustic substrate and for functional optical effects. It is, however, well known that single crystals are difficult to fabricate because of the instability caused by temperature, external stress, and other factors. PMID:25265169

Fujiuchi, Yukiko; Morita, Takeshi

2014-10-01

166

Multiscale Modeling of Mechanical Shock Behavior of Environmentally-Benign Lead-Free Solders in Electronic Packaging  

NASA Astrophysics Data System (ADS)

With the increasing focus on developing environmentally benign electronic packages, lead-free solder alloys have received a great deal of attention. Mishandling of packages, during manufacture, assembly, or by the user may cause failure of solder joint. A fundamental understanding of the behavior of lead-free solders under mechanical shock conditions is lacking. Reliable experimental and numerical analyses of lead-free solder joints in the intermediate strain rate regime need to be investigated. This dissertation mainly focuses on exploring the mechanical shock behavior of lead-free tin-rich solder alloys via multiscale modeling and numerical simulations. First, the macroscopic stress/strain behaviors of three bulk lead-free tin-rich solders were tested over a range of strain rates from 0.001/s to 30/s. Finite element analysis was conducted to determine appropriate specimen geometry that could reach a homogeneous stress/strain field and a relatively high strain rate. A novel self-consistent true stress correction method is developed to compensate the inaccuracy caused by the triaxial stress state at the post-necking stage. Then the material property of micron-scale intermetallic was examined by microcompression test. The accuracy of this measure is systematically validated by finite element analysis, and empirical adjustments are provided. Moreover, the interfacial property of the solder/intermetallic interface is investigated, and a continuum traction-separation law of this interface is developed from an atomistic-based cohesive element method. The macroscopic stress/strain relation and microstructural properties are combined together to form a multiscale material behavior via a stochastic approach for both solder and intermetallic. As a result, solder is modeled by porous plasticity with random voids, and intermetallic is characterized as brittle material with random vulnerable region. Thereafter, the porous plasticity fracture of the solders and the brittle fracture of the intermetallics are coupled together in one finite element model. Finally, this study yields a multiscale model to understand and predict the mechanical shock behavior of lead-free tin-rich solder joints. Different fracture patterns are observed for various strain rates and/or intermetallic thicknesses. The predictions have a good agreement with the theory and experiments.

Fei, Huiyang

167

Piezoelectric dispenser based on a piezoelectric-metal-cavity actuator  

Microsoft Academic Search

A piezoelectric dispenser has been fabricated based on the idea of a piezoelectric-metal-cavity (PMC) actuator. The PMC actuator consists of a metal ring sandwiched between two identical piezoelectric unimorphs. The radial contraction of the piezoelectric ceramic is converted into a flextensional motion of the unimorph, causing a large flexural displacement in the center part of the actuator. With the PMC

K. H. Lam; C. L. Sun; K. W. Kwok; H. L. W. Chan

2009-01-01

168

NASA-DoD Lead-Free Electronics Project. DRAFT Joint Test Report  

NASA Technical Reports Server (NTRS)

The use of conventional tin-lead (SnPb) in circuit board manufacturing is under ever-increasing political scrutiny due to increasing regulations concerning lead. The "Restriction of Hazardous Substances" (RoHS) directive enacted by the European Union (EU) and a pact between the United States National Electronics Manufacturing Initiative (NEMI), Europe's Soldertec at Tin Technology Ltd. and the Japan Electronics and Information Technology Industries Association (JEITA) are just two examples where worldwide legislative actions and partnerships/agreements are affecting the electronics industry. As a result, many global commercial-grade electronic component suppliers are initiating efforts to transition to lead-free (Pb-free) in order to retain their worldwide market. Pb-free components are likely to find their way into the inventory of aerospace or military assembly processes under current government acquisition reform initiatives. Inventories "contaminated" by Pb-free will result in increased risks associated with the manufacturing, product reliability, and subsequent repair of aerospace and military electronic systems. Although electronics for military and aerospace applications are not included in the RoHS legislation, engineers are beginning to find that the commercial industry's move towards RoHS compliance has affected their supply chain and changed their parts. Most parts suppliers plan to phase out their non-compliant, leaded production and many have already done so. As a result, the ability to find leaded components is getting harder and harder. Some buyers are now attempting to acquire the remaining SnPb inventory, if it's not already obsolete. Original Equipment Manufacturers (OEMs), depots, and support contractors have to be prepared to deal with an electronics supply chain that increasingly provides more and more parts with Pb-free finishes-some labeled no differently than their Pb counterparts-while at the same time providing the traditional Pb parts. The longer the transition period, the greater the likelihood of Pb-free parts inadvertently being mixed with Pb parts and ending up on what are supposed to be Pb systems. As a result, OEMs, depots, and support contractors need to take action now to either abate the influx of Pb-free parts, or accept it and deal with the likely interim consequences of reduced reliability due to a wide variety of matters, such as Pb contamination, high temperature incompatibility, and tin whiskering. Allowance of Pb-free components produces one of the greatest risks to the reliability of a weapon system. This is due to new and poorly understood failure mechanisms, as well as unknown long-term reliability. If the decision is made to consciously allow Pb-free solder and component finishes into SnPb electronics, additional effort (and cost) will be required to make the significant number of changes to drawings and task order procedures. This project is a follow-on effort to the Joint Council on Aging Aircraft/Joint Group on Pollution Prevention (JCAA/JG-PP) Pb-free Solder Project which was the first group to test the reliability of Pb-free solder joints against the requirements of the aerospace and military community.

Kessel, Kurt

2011-01-01

169

Recent advances of conductive adhesives as a lead-free alternative in electronic packaging: Materials, processing, reliability and applications  

Microsoft Academic Search

Tin–lead solder alloys are widely used in the electronic industry. They serve as interconnects that provide the conductive path required to achieve connection from one circuit element to another. There are increasing concerns with the use of tin–lead alloy solders in recognition of hazards of using lead. Lead-free solders and electrically conductive adhesives (ECAs) have been considered as the most

Yi Li; C. P. Wong

2006-01-01

170

Shear Strength of Eutectic Sn-Bi Lead-Free Solders After Corrosion Testing and Thermal Aging  

NASA Astrophysics Data System (ADS)

Low-cost manufacturing in the electronics industry is becoming more demanding, particularly in the production of consumer electronics. Such manufacturing processes require reliable and low-cost lead-free solders. Among the low temperature lead-free solders, eutectic Sn-Bi solder has attracted a great deal of interest since it offers good reliability comparable to that of Sn-Pb solders. In this paper, the shear strength of eutectic 42Sn-58Bi (wt.%) lead-free solder was studied using combinations of environmental tests including thermal aging at 100 °C, salt spray test, and a sequential combination of these tests. Microstructural studies on samples were performed at different time intervals of testing. To study the effect of salt spray and thermal aging on the mechanical reliability, shear testing was performed on the samples. Failure analysis including fractography on samples was conducted at different time intervals using a scanning electron microscope. Considerable corrosion was observed after the salt spray test. This was found to have a significant effect on the shear strength of the solder joints. Additionally, thermal aging was found to cause coarsening and to increase the thickness of intermetallic layers. This was also found to adversely affect the shear strength. The combination test was found to have the most significant effect, as the lowest shear strengths were seen after this testing.

Mostofizadeh, Milad; Pippola, Juha; Frisk, Laura

2014-05-01

171

The characterisation of lead-free thick-film resistors on different low temperature Co-fired ceramics substrates  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Lead free thick film resistors based on ruthenium oxide were developed. ? The compatibility of resistors with different LTCC substrates was evaluated. ? The interactions between resistors and glassy LTCC substrates were not detected. ? Electrical characteristics were comparable with commercial thick film resistors. -- Abstract: Lead-free thick-film resistors were synthesised and investigated. The thick-film resistor materials with nominal sheet resistivities from 50 ohm/sq. to 50 kohm/sq. were prepared using combinations of two lead-free glasses with reflow temperatures at 940 °C and 1240 °C, respectively, and two RuO{sub 2} powders (fine-grained and coarse-grained RuO{sub 2}). The thick-film resistors were printed and fired on alumina and on low temperature co-fired ceramics substrates and fired at 850 °C and 950 °C. The fired resistors were investigated by X-ray powder diffraction, by scanning electron microscopy and by energy dispersive X-ray analysis. The sheet resistivities, temperature coefficients of resistivity, gauge factors and noise indices were measured.

Hrovat, Marko, E-mail: marko.hrovat@ijs.si [Jožef Stefan Institute, Jamova Cesta 39, SI-1000 Ljubljana (Slovenia) [Jožef Stefan Institute, Jamova Cesta 39, SI-1000 Ljubljana (Slovenia); CoE NAMASTE, Jamova Cesta 39, SI-1000 Ljubljana (Slovenia); Kielbasinski, Konrad [Institute of Electronic Materials Technology, Wólczy?ska 133, 01-919 Warsaw (Poland) [Institute of Electronic Materials Technology, Wólczy?ska 133, 01-919 Warsaw (Poland); Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Makarovi?, Kostja [Jožef Stefan Institute, Jamova Cesta 39, SI-1000 Ljubljana (Slovenia) [Jožef Stefan Institute, Jamova Cesta 39, SI-1000 Ljubljana (Slovenia); CoE NAMASTE, Jamova Cesta 39, SI-1000 Ljubljana (Slovenia); Belavi?, Darko [HIPOT-RR d.o.o., Šentpeter 18, SI-8222 Oto?ec (Slovenia) [HIPOT-RR d.o.o., Šentpeter 18, SI-8222 Oto?ec (Slovenia); CoE NAMASTE, Jamova Cesta 39, SI-1000 Ljubljana (Slovenia); Jakubowska, Malgorzata [Institute of Electronic Materials Technology, Wólczy?ska 133, 01-919 Warsaw (Poland) [Institute of Electronic Materials Technology, Wólczy?ska 133, 01-919 Warsaw (Poland); Faculty of Mechatronics, Warsaw University of Technology, ?w. Andrzeja Boboli 8, 02-525 Warsaw (Poland)

2012-12-15

172

Advantages & Challenges of Cold Ball Pull Test vs Conventional Ball Shear Test in the Assessment of Lead-free Solder Joint Performance  

Microsoft Academic Search

A comparison study was done between cold ball pull (CBP) test vs. the conventional ball shear test to further understand the advantages & challenges of CBP test as a method to assess lead-free solder joint performance. From this study, CBP was found to be a better and preferred tool that is able to identify poor lead free solder joint and

Eu Poh Leng; Min Ding; Hoh Huey Jiun; I. Ahmad; K. Hazlinda

2006-01-01

173

University of California, Irvine Environmental Health and Safety www.ehs.uci.edu Questions Call: (949) 824-6200 Version 1.0 Lead Free UCI  

E-print Network

at an angle (/ / / / /). The stripes appear light beige under normal conditions and darken in the autoclave/Lead Free Steam Indicator Tape LF2-048 PI Name: Lab Contact Name: Building: Room: Phone: 1. Number of rolls of lead containing autoclave tape to be disposed of: 2. Number of rolls of lead free autoclave requested

George, Steven C.

174

Adaptive piezoelectric sensoriactuator  

NASA Technical Reports Server (NTRS)

An adaptive algorithm implemented in digital or analog form is used in conjunction with a voltage controlled amplifier to compensate for the feedthrough capacitance of piezoelectric sensoriactuator. The mechanical response of the piezoelectric sensoriactuator is resolved from the electrical response by adaptively altering the gain imposed on the electrical circuit used for compensation. For wideband, stochastic input disturbances, the feedthrough capacitance of the sensoriactuator can be identified on-line, providing a means of implementing direct-rate-feedback control in analog hardware. The device is capable of on-line system health monitoring since a quasi-stable dynamic capacitance is indicative of sustained health of the piezoelectric element.

Clark, Jr., Robert L. (Inventor); Vipperman, Jeffrey S. (Inventor); Cole, Daniel G. (Inventor)

1996-01-01

175

Piezoelectric Polymer Shock Gauges  

NASA Astrophysics Data System (ADS)

The science and technology of piezoelectric materials has long been dominated by the availability of specific materials with particular properties. Piezoelectric PVDF (Poly(vinylidene fluoride) polymer and copolymers of PVDF with trifluoroethylene have shown to have the potential for new shock-wave sensors. Since 1981 through 1995, the piezoelectric response of PVDF was studied in a cooperative effort with François Bauer of ISL, France, R.A. Graham of Sandia National Laboratories and L.M. Lee of Ktech Corporation, Albuquerque. Among the known piezoelectric polymers, the PVDF plays an important role in measuring mechanical and physical state of matter under shock loading. The present paper presents the history of the development of the PVDF gauge. After 24 years of research in this area, main relevant results and data obtained are summarized as well as some original applications of the PVDF gauges.

Bauer, F.

2006-07-01

176

Laminated piezoelectric transformer  

NASA Technical Reports Server (NTRS)

A laminated piezoelectric transformer is provided using the longitudinal vibration modes for step-up voltage conversion applications. The input portions are polarized to deform in a longitudinal plane and are bonded to an output portion. The deformation of the input portions is mechanically coupled to the output portion, which deforms in the same longitudinal direction relative to the input portion. The output portion is polarized in the thickness direction relative its electrodes, and piezoelectrically generates a stepped-up output voltage.

Vazquez Carazo, Alfredo (Inventor)

2006-01-01

177

Piezoelectric Energy Harvesting Solutions  

PubMed Central

This paper reviews the state of the art in piezoelectric energy harvesting. It presents the basics of piezoelectricity and discusses materials choice. The work places emphasis on material operating modes and device configurations, from resonant to non-resonant devices and also to rotational solutions. The reviewed literature is compared based on power density and bandwidth. Lastly, the question of power conversion is addressed by reviewing various circuit solutions. PMID:24618725

Caliò, Renato; Rongala, Udaya Bhaskar; Camboni, Domenico; Milazzo, Mario; Stefanini, Cesare; de Petris, Gianluca; Oddo, Calogero Maria

2014-01-01

178

Piezoelectrically Enhanced Photocathodes  

NASA Technical Reports Server (NTRS)

Doping of photocathodes with materials that have large piezoelectric coefficients has been proposed as an alternative means of increasing the desired photoemission of electrons. Treating cathode materials to increase emission of electrons is called "activation" in the art. It has been common practice to activate photocathodes by depositing thin layers of suitable metals (usually, cesium). Because cesium is unstable in air, fabrication of cesiated photocathodes and devices that contain them must be performed in sealed tubes under vacuum. It is difficult and costly to perform fabrication processes in enclosed, evacuated spaces. The proposed piezoelectrically enhanced photocathodes would have electron-emission properties similar to those of cesiated photocathodes but would be stable in air, and therefore could be fabricated more easily and at lower cost. Candidate photocathodes include nitrides of elements in column III of the periodic table . especially compounds of the general formula Al(x)Ga(1.x)N (where 0< or = x < or =.1). These compounds have high piezoelectric coefficients and are suitable for obtaining response to ultraviolet light. Fabrication of a photocathode according to the proposal would include inducement of strain in cathode layers during growth of the layers on a substrate. The strain would be induced by exploiting structural mismatches among the various constituent materials of the cathode. Because of the piezoelectric effect in this material, the strain would give rise to strong electric fields that, in turn, would give rise to a high concentration of charge near the surface. Examples of devices in which piezoelectrically enhanced photocathodes could be used include microchannel plates, electron- bombarded charge-coupled devices, image tubes, and night-vision goggles. Piezoelectrically enhanced photocathode materials could also be used in making highly efficient monolithic photodetectors. Highly efficient and stable piezoelectrically enhanced, ultraviolet-sensitive photocathodes and photodetectors could be fabricated by use of novel techniques for growing piezoelectrically enhanced layers, in conjunction with thinning and dopant-selective etching techniques.

Beach, Robert A.; Nikzad, Shouleh; Bell, Lloyd Douglas; Strittmatter, Robert

2011-01-01

179

Process for producing gasoline of high octane number and particularly lead free gasoline, from olefininc c3-c4 cuts  

SciTech Connect

Lead free gasoline of high octane number is obtained from C/sub 3/ and C/sub 4/ olefinic cuts as follows: propylene contained in the C/sub 3/ cut is oligomerized, at least 80% of the isobutene and less than 40% of the n-butenes of the C/sub 4/ cut are oligomerized to form an oligomerizate distilling in the gasoline range, which is separated from the unreacted C/sub 4/ hydrocarbons, the latter are subsequently alkylated to form a gasoline fraction which can be admixed with the oligomerizates of the Cnumber and the C/sub 4/ cuts to produce the desired high octane gasoline.

Hellin, M.; Juguin, B.; Torck, B.; Vu, Q. D.

1981-05-19

180

Piezoelectric Ceramics and Their Applications  

ERIC Educational Resources Information Center

Describes the piezoelectric effect in ceramics and presents a quantitative representation of this effect. Explains the processes involved in the manufacture of piezoelectric ceramics, the materials used, and the situations in which they are applied. (GS)

Flinn, I.

1975-01-01

181

High temperature piezoelectric drill  

NASA Astrophysics Data System (ADS)

The current NASA Decadal mission planning effort has identified Venus as a significant scientific target for a surface in-situ sampling/analyzing mission. The Venus environment represents several extremes including high temperature (460°C), high pressure (~9 MPa), and potentially corrosive (condensed sulfuric acid droplets that adhere to surfaces during entry) environments. This technology challenge requires new rock sampling tools for these extreme conditions. Piezoelectric materials can potentially operate over a wide temperature range. Single crystals, like LiNbO3, have a Curie temperature that is higher than 1000°C and the piezoelectric ceramics Bismuth Titanate higher than 600°C. A study of the feasibility of producing piezoelectric drills that can operate in the temperature range up to 500°C was conducted. The study includes the high temperature properties investigations of engineering materials and piezoelectric ceramics with different formulas and doping. The drilling performances of a prototype Ultrasonic/Sonic Drill/Corer (USDC) using high temperate piezoelectric ceramics and single crystal were tested at temperature up to 500°C. The detailed results of our study and a discussion of the future work on performance improvements are presented in this paper.

Bao, Xiaoqi; Scott, James; Boudreau, Kate; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom; Zhang, Shujun

2009-03-01

182

Effect of cooling rate on structure and creep behavior of Sn-0.7Cu-0.5Zn lead-free solder alloy  

NASA Astrophysics Data System (ADS)

The influence of cooling rate on the structure, melting, hardness and indentation creep behavior of the Sn-0.7Cu-0.5Zn lead-free solder alloy has been studied by XRD, DSC and Vickers microhardness tester, respectively. The study was carried out for the alloy prepared at two different cooling rates of 3.5 °C/s and 11.7 × 10-3 ^circC/s. The results showed that the cooling rate significantly affects the structure, melting and mechanical properties of this alloy. Cu atoms are restricted in the formation of the intermetallic compound (IMC) Cu{6}Sn{5} embedded in Sn-matrix in the slow cooled sample. Cu{3}Sn compound was detected in the fast cooled sample. The Zn-phase has not been detected by the X-ray diffraction analysis, which means a complete solubility of Zn in Sn-matrix has been obtained. The crystallite size of the Sn-matrix phase in the slow cooled sample was found to be 54.4 nm, while the value of the fast cooled sample was found to be 48.5 nm. This means the fast cooling condition caused grain refinement. This refinement leads to decrease the melting point from 222.7 to 221.2 °C and increase microhardness from 16.4 to 18.2 kg/mm2. Furthermore, fast cooling condition improved the creep resistance of Sn-0.7Cu-0.5Zn alloy than that of the slow cooling condition. in here

Gouda, E. S.

2009-11-01

183

Active Piezoelectric Diaphragms  

NASA Technical Reports Server (NTRS)

Several active piezoelectric diaphragms were fabricated by placing unelectroded piezoelectric disks between copper clad films patterned with Inter-Circulating Electrodes "ICE". When a voltage potential is applied to the electrodes, the result is radially distributed electric field that mechanically strains the piezo-ceramic along the Z-axis (perpendicular to the applied electric field), rather than the expected in-plane (XY-axis) direction. Unlike other out of plane piezoelectric actuators, which are benders, these Radial Field Diaphragms (RFDs) strain concentrically yet afford high displacements while maintaining a constant circumference. This paper covers the fabrication and characterization of these diaphragms as a function of poling field strength, ceramic diameter and line spacing, as well as the surface topography, the resulting strain field and displacement as a function of applied voltage ranging from DC to 10 Hz.

Bryant, Robert G.; Effinger, Robert T., IV; Aranda, Isaiah, Jr.; Copeland, Ben M.; Covington, Ed W., III

2002-01-01

184

Piezoelectric hydraulic pump performance  

NASA Astrophysics Data System (ADS)

A piezohydraulic pump making use of the step and repeat capability of piezoelectric actuators has been developed for actuation of aircraft control surfaces. The piezohydraulic pump utilizes a piezoelectric stack actuator to drive a piston in a cylinder. The cylinder is fitted with two check valves. On the compression stroke, oil is forced out of the cylinder. On the intake stroke, oil is drawn into the cylinder. The oil is used to drive a linear actuator. The actuator was driven at 7cm/sec with a 271N (61lb) blocking force. To achieve this, the piezoelectric stack actuator was driven at 60Hz with a switching power supply. The system utilizes an accumulator to eliminate cavitation. This work discusses piezohydraulic pumping theory, pump design, and pump performance. Consideration of pump performance includes the effects of varying accumulator pressure, hydraulic oil viscosity, and load imposed on the linear actuator.

Mauck, Lisa D.; Oates, William S.; Lynch, Christopher S.

2001-06-01

185

Active piezoelectric diaphragms  

NASA Astrophysics Data System (ADS)

Several active piezoelectric diaphragms were fabricated by placing unelectroded piezoelectric disks between copper clad films patterned with Inter-Circulating Electrodes (ICE). When a voltage potential is applied to the electrodes, the result is radially distributed electric field that mechanically strains the piezo-ceramic along the Z-axis, rather than the expected in-plane direction. Unlike other out of plane piezoelectric actuators, which are benders, these Radial Field Diaphragms strain concentrically yet afford high displacements while maintaining a constant circumference. This paper covers the fabrication and characterization of these diaphragms as a function of poling field strength, ceramic diameter and line spacing, as well as the surface topography, the resulting strain field and displacement as a function of applied voltage ranging from DC to 10 Hz.

Bryant, Robert G.; Effinger, Robert T., IV; Aranda, Isaiah, Jr.; Copeland, Ben M., Jr.; Covington, Ed W., III

2002-07-01

186

Reduced risk of acute poisoning in Australian cattle from used motor oils after introduction of lead-free petrol.  

PubMed

Lead (Pb) poisoning of cattle has been relatively common in Australia and sump oil has been identified as an important cause of Pb toxicity for cattle because they seem to have a tendency to drink it. Lead-free petrol has been available in Australia since 1975, so the aim of this study was to assess the current risk to cattle from drinking used automotive oils. Sump or gear box oil was collected from 56 vehicles being serviced. The low levels of Pb found suggest that the removal of leaded petrol from the Australian market as a public health measure has benefited cattle by eliminating the risk of acute poisoning from used engine oil. PMID:20553575

Burren, B G; Reichmann, K G; McKenzie, R A

2010-06-01

187

Emission factors for gases and particle-bound substances produced by firing lead-free small-caliber ammunition.  

PubMed

Lead-free ammunition is becoming increasingly popular because of the environmental and human health issues associated with the use of leaded ammunition. However, there is a lack of data on the emissions produced by firing such ammunition. We report emission factors for toxic gases and particle-bound compounds produced by firing lead-free ammunition in a test chamber. Carbon monoxide, ammonia, and hydrogen cyanide levels within the chamber were analysed by Fourier transform infrared spectroscopy, while total suspended particles and respirable particles were determined gravimetrically. The metal content of the particulate emissions was determined and the associated organic compounds were characterized in detail using a method based on thermal desorption coupled to gas chromatography and mass spectrometry. The particulate matter (?30 mg/round) consisted primarily of metals such as Cu, Zn, and Fe along with soot arising from incomplete combustion. Nitrogen-containing heterocyclic aromatic compounds such as carbazole, quinolone, and phenazine were responsible for some of the 25 most significant chromatographic peaks, together with PAHs, diphenylamine, and phthalates. Emission factors were determined for PAHs and oxygenated PAHs; the latter were less abundant in the gun smoke particles than in domestic dust and diesel combustion smoke. This may be due to the oxygen-deficient conditions that occur when the gun is fired. By using an electrical low pressure impactor, it was demonstrated that more than 90% of the particles produced immediately after firing the weapon had diameters of less than 30 nm, and so most of the gun smoke particles belonged to the nanoparticle regime. PMID:24188168

Wingfors, H; Svensson, K; Hägglund, L; Hedenstierna, S; Magnusson, R

2014-01-01

188

Mechanical confinement for improved energy storage density in BNT-BT-KNN lead-free ceramic capacitors  

SciTech Connect

With the advent of modern power electronics, embedded circuits and non-conventional energy harvesting, the need for high performance capacitors is bound to become indispensible. The current state-of-art employs ferroelectric ceramics and linear dielectrics for solid state capacitance. However, lead-free ferroelectric ceramics propose to offer significant improvement in the field of electrical energy storage owing to their high discharge efficiency and energy storage density. In this regards, the authors have investigated the effects of compressive stress as a means of improving the energy storage density of lead-free ferroelectric ceramics. The energy storage density of 0.91(Bi{sub 0.5}Na{sub 0.5})TiO{sub 3}-0.07BaTiO{sub 3}-0.02(K{sub 0.5}Na{sub 0.5})NbO{sub 3} ferroelectric bulk ceramic was analyzed as a function of varying levels of compressive stress and operational temperature .It was observed that a peak energy density of 387 mJ.cm{sup -3} was obtained at 100 MPa applied stress (25{sup o}C). While a maximum energy density of 568 mJ.cm{sup -3} was obtained for the same stress at 80{sup o}C. These values are indicative of a significant, 25% and 84%, improvement in the value of stored energy compared to an unloaded material. Additionally, material's discharge efficiency has also been discussed as a function of operational parameters. The observed phenomenon has been explained on the basis of field induced structural transition and competitive domain switching theory.

Chauhan, Aditya; Patel, Satyanarayan; Vaish, Rahul, E-mail: rahul@iitmandi.ac.in [School of Engineering, Indian Institute of Technology Mandi, 175 001 (India)

2014-08-15

189

Design of optimized piezoelectric HDD-sliders  

NASA Astrophysics Data System (ADS)

As storage data density in hard-disk drives (HDDs) increases for constant or miniaturizing sizes, precision positioning of HDD heads becomes a more relevant issue to ensure enormous amounts of data to be properly written and read. Since the traditional single-stage voice coil motor (VCM) cannot satisfy the positioning requirement of high-density tracks per inch (TPI) HDDs, dual-stage servo systems have been proposed to overcome this matter, by using VCMs to coarsely move the HDD head while piezoelectric actuators provides fine and fast positioning. Thus, the aim of this work is to apply topology optimization method (TOM) to design novel piezoelectric HDD heads, by finding optimal placement of base-plate and piezoelectric material to high precision positioning HDD heads. Topology optimization method is a structural optimization technique that combines the finite element method (FEM) with optimization algorithms. The laminated finite element employs the MITC (mixed interpolation of tensorial components) formulation to provide accurate and reliable results. The topology optimization uses a rational approximation of material properties to vary the material properties between 'void' and 'filled' portions. The design problem consists in generating optimal structures that provide maximal displacements, appropriate structural stiffness and resonance phenomena avoidance. The requirements are achieved by applying formulations to maximize displacements, minimize structural compliance and maximize resonance frequencies. This paper presents the implementation of the algorithms and show results to confirm the feasibility of this approach.

Nakasone, Paulo H.; Yoo, Jeonghoon; Silva, Emilio C. N.

2010-04-01

190

Lead-free solder  

DOEpatents

A Sn--Ag--Cu eutectic alloy is modified with one or more low level and low cost alloy additions to enhance high temperature microstructural stability and thermal-mechanical fatigue strength without decreasing solderability. Purposeful fourth or fifth element additions in the collective amount not exceeding about 1 weight % (wt. %) are added to Sn--Ag--Cu eutectic solder alloy based on the ternary eutectic Sn--4.7%Ag--1.7%Cu (wt. %) and are selected from the group consisting essentially of Ni, Fe, and like-acting elements as modifiers of the intermetallic interface between the solder and substrate to improve high temperature solder joint microstructural stability and solder joint thermal-mechanical fatigue strength.

Anderson, Iver E. (Ames, IA); Terpstra, Robert L. (Ames, IA)

2001-05-15

191

Improper ferroelectricity and piezoelectric responses in rhombohedral (A,A')B2O6 perovskite oxides  

NASA Astrophysics Data System (ADS)

High-temperature electronic materials are in constant demand as the required operational range for various industries increases. Here we design (A,A')B2O6 perovskite oxides with [111] "rock salt" A-site cation order and predict them to be potential high-temperature piezoelectric materials. By selecting bulk perovskites which have a tendency towards only out-of-phase BO6 rotations, we avoid possible staggered ferroelectric to paraelectric phase transitions while also retaining noncentrosymmetric crystal structures necessary for ferro- and piezoelectricity. Using density functional theory calculations, we show that (La,Pr)Al2O6 and (Ce,Pr)Al2O6 display spontaneous polarizations in their polar ground state structures; we also compute the dielectric and piezoelectric constants for each phase. Additionally, we predict the critical phase transition temperatures for each material from first-principles to demonstrate that the piezoelectric responses, which are comparable to traditional lead-free piezoelectrics, should persist to high temperature. These features make the rock salt A-site-ordered aluminates candidates for high-temperature sensors, actuators, or other electronic devices.

Young, Joshua; Rondinelli, James M.

2014-05-01

192

PRODUCT DATA Piezoelectric Accelerometer  

E-print Network

element used is a PZ 23 lead zirconate titanate element. The housing material is titanium. Calibration around a triangular centre post. The ring prestresses the piezoelectric elements to give a high degree Characteristics Dimensions See outline drawing Weight gram (oz.) 17 (0.6) Case Material Titanium Connector 10

Phani, A. Srikantha

193

Piezoelectric actuators control unit  

Microsoft Academic Search

Superconductive cavities for future linear accelerators, such as ILC, have extremely large quality factors that require an effective stabilization with both slow and fast tuners. Piezoelectric actuators are the most common choice for fast tuners, but one drawback for large scale applications is the limited bandwidth and the large cost of commercially available drivers. In this paper we present a

Franco Bedeschi; Stefano Galeotti; Alberto Gennai; Carlo Magazzu; Diego Passuello; Elena Pedreschi; Franco Spinella; Federico Paoletti

2010-01-01

194

Origin of piezoelectricity in monolayer halogenated graphane piezoelectrics  

NASA Astrophysics Data System (ADS)

Periodic patterning with adatoms or defect is one of the methods for opening the band gap of graphene. In particular, under certain configurations controlled by the order of hydrogen and halogen atoms attached on graphene, inversion symmetry of graphene can be broken to give piezoelectricity as well as pyroelectricity. Using first-principles calculations, we examine the structural stability and electronic properties of four polar conformations of halogenated graphane (C2HX)n to understand the origin of piezoelectricity in this two-dimensional system. The formation energies and piezoelectric coefficients manifest that the four conformations of (C2HF)n are energetically stable with considerable piezoelectricity. We find that the electronic contribution of the proper piezoelectricity in (C2HF)n is mainly related to the change of the electron distribution around F atoms. By substituting flourine with chlorine, we confirm that the piezoelectricity enhances at the expense of stability degradation.

Kim, Hye Jung; Noor-A-Alam, Mohammad; Son, Jong Yeog; Shin, Young-Han

2014-05-01

195

Fatigue failure kinetics and structural changes in lead-free interconnects due to mechanical and thermal cycling  

NASA Astrophysics Data System (ADS)

Environmental and human health concerns drove European parliament to mandate the Reduction of Hazardous Substances (RoHS) for electronics. This was enacted in July 2006 and has practically eliminated lead in solder interconnects. There is concern in the electronics packaging community because modern lead-free solder is rich in tin. Presently, near-eutectic tin-silver-copper solders are favored by industry. These solders are stiffer than the lead-tin near-eutectic alloys, have a higher melting temperature, fewer slip systems, and form intermetallic compounds (IMC) with Cu, Ni and Ag, each of which tend to have a negative effect on lifetime. In order to design more reliable interconnects, the experimental observation of cracking mechanisms is necessary for the correct application of existing theories. The goal of this research is to observe the failure modes resulting from mode II strain and to determine the damage mechanisms which describe fatigue failures in 95.5 Sn- 4.0 Ag - 0.5 Cu wt% (SAC405) lead-free solder interconnects. In this work the initiation sites and crack paths were characterized for SAC405 ball-grid array (BGA) interconnects with electroless-nickel immersion-gold (ENIG) pad-finish. The interconnects were arranged in a perimeter array and tested in fully assembled packages. Evaluation methods included monotonic and displacement controlled mechanical shear fatigue tests, and temperature cycling. The specimens were characterized using metallogaphy, including optical and electron microscopy as well as energy dispersive spectroscopy (EDS) and precise real-time electrical resistance structural health monitoring (SHM). In mechanical shear fatigue tests, strain was applied by the substrates, simulating dissimilar coefficients of thermal expansion (CTE) between the board and chip-carrier. This type of strain caused cracks to initiate in the soft Sn-rich solder and grow near the interface between the solder and intermetallic compounds (IMC). The growth near the interface was found to be caused by dislocation pile-ups at the IMC when the plastic zone ahead of the crack tip reached this interface. In temperature cycling testing, strains arose within the interconnect due to CTE mismatch between the solder and IMC. The substrates had matched CTE for all specimens in this research. Because of this, all the temperature cycling cracks were observed at interfaces, generally between the solder and IMC. Additionally, real-time electrical resistance may be a useful non-destructive evaluation (NDE) tool for the empirical observation of fatigue cracking in ball-grid arrays (BGA) during both mechanical and temperature cycling tests.

Fiedler, Brent Alan

196

Piezoelectric Resonator with Two Layers  

NASA Technical Reports Server (NTRS)

A piezoelectric resonator device includes: a top electrode layer with a patterned structure, a top piezoelectric layer adjacent to the top layer, a middle metal layer adjacent to the top piezoelectric layer opposite the top layer, a bottom piezoelectric layer adjacent to the middle layer opposite the top piezoelectric layer, and a bottom electrode layer with a patterned structure and adjacent to the bottom piezoelectric layer opposite the middle layer. The top layer includes a first plurality of electrodes inter-digitated with a second plurality of electrodes. A first one of the electrodes in the top layer and a first one of the electrodes in the bottom layer are coupled to a first contact, and a second one of the electrodes in the top layer and a second one of the electrodes in the bottom layer are coupled to a second contact.

Stephanou, Philip J. (Inventor); Black, Justin P. (Inventor)

2013-01-01

197

Piezoelectric step-motion actuator  

DOEpatents

A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

Mentesana; Charles P. (Leawood, KS)

2006-10-10

198

Effects of Cu, Zn on the Wettability and Shear Mechanical Properties of Sn-Bi-Based Lead-Free Solders  

NASA Astrophysics Data System (ADS)

Effects of minor Cu, Zn additions on the wettability, microstructures, and shear properties of Sn-Bi-based lead-free solder joints were investigated. The results show that a Cu addition promotes the wetting ratio of solder alloy, while Zn creates the opposite effect. The Cu5Zn8 intermetallic compound layer at the interface of Sn-40Bi-2Zn-0.1Cu and the Cu substrate alters the surface tension, which increases the contact angle. Also, this type of intermetallic compound contributes to the change of three wetting indicators. A proper amount of Cu, Zn increased the wetting force and decreased the wetting time, while the variation in the trend of withdrawing force is consistent with that of contact angle. From joint shear test results, the shear force decreased in the following order: Sn-40Bi-0.1Cu, Sn-58Bi, and Sn-40Bi-2Zn-0.1Cu solder joints. Cu additions refined the grain size of the Bi-rich phase and decreased the interface brittleness, which is the reason for the improvement of the shear strength of Sn-40Bi-0.1Cu solder joints. In contrast, Zn weakened the shear strength due to the brittle nature of the Zn-rich phase and the chemical activity of Zn.

Shen, Jun; Pu, Yayun; Yin, Henggang; Tang, Qin

2015-01-01

199

(Na, Bi)TiO3 based lead-free ferroelectric thin films on Si substrate for pyroelectric infrared sensors  

NASA Astrophysics Data System (ADS)

In this study, we report ferroelectric and pyroelectric properties of (Na0.5Bi0.5)TiO3-BaTiO3 (NBT-BT) thin films on Si substrates using chemical solution deposition for the first time. The NBT-BT thin films deposited on Pt/Ti/SiO2/Si substrates have exhibited a typical hysteresis loop with remnant polarization of 5 ?C/cm2 and coercive field of 80 kV/cm. Furthermore NBT-BT films showed pyroelectricity with pyroelectric coefficient of 0.6×10-8 C/cm2K. Monolithic-integration of Si electronics and lead-free ferroelectric NBT thin films has been archived using SiN passivation layer. It was previously believed that LSI processes could not incorporate any sodium-containing material which would cause characteristic degradation, such as threshold voltage shift. In this work, no threshold voltage shift in MOS characteristics was observed using this SiN layer. The SiN layer not only blocked diffusion from NBT chemistry, but also from crystallized NBT films during NBT formation process.

Akai, D.; Yoshita, R.; Ishida, M.

2013-04-01

200

Enhancing the Ductility of Sn-Ag-Cu Lead-Free Solder Joints by Addition of Compliant Intermetallics  

NASA Astrophysics Data System (ADS)

Tin (Sn)-rich lead (Pb)-free solders containing rare-earth (RE) elements have been shown to exhibit desirable attributes of microstructural refinement and enhanced ductility relative to conventional Sn-3.9Ag-0.7Cu lead-free solder, due to the unique mechanical properties of RE-Sn intermetallics. However, the roles of soft intermetallic phase in the enhanced ductility of Pb-free solder still need to be further investigated. In this paper, Ca and Mn were selected as doping elements for Sn-Ag-Cu solder. The mechanical properties of Ca-Sn and Mn-Sn intermetallics as a function of indentation depth were measured by nanoindentation using the continuous stiffness method (CSM). The microstructure and mechanical properties of as-reflowed Ca- and Mn-containing Sn-Ag-Cu solder joints were studied and compared with those of conventional Sn-Ag-Cu and RE-containing solder joints. It is shown that soft intermetallics result in higher ductility in Pb-free solders.

Xie, H. X.; Chawla, N.

2013-03-01

201

Methodology for analyzing stress states during in-situ thermomechanical cycling in individual lead free solder joints using synchrotron radiation  

SciTech Connect

To examine how a lead-free solder joint deforms in a thermal cycling environment, both the elastic and plastic stress and strain behavior must be understood. Methods to identify evolution of the internal strain (stress) state during thermal cycling are described. A slice of a package containing a single row of solder joints was thermally cycled from 0 C to 100 C with a period of about 1 h with concurrent acquisition of transmission Laue patterns using synchrotron radiation. These results indicated that most joints are single crystals, with some being multicrystals with no more than a few Sn grain orientations. Laue patterns were analyzed to estimate local strains in different crystal directions at different temperatures during a thermal cycle. While the strains perpendicular to various crystal planes all vary in a similar way, the magnitude of strain varies. The specimens were subsequently given several hundred additional thermal cycles and measured again to assess changes in the crystal orientations. These results show that modest changes in crystal orientations occur during thermal cycling.

Zhou, Bite; Bieler, Thomas R.; Lee , Tae-Kyu; Liu, Kuo-Chuan; (MSU); (Cisco)

2010-07-22

202

A PZT micro-actuated suspension for high TPI hard disk servo systems  

Microsoft Academic Search

A piezoelectrically actuated suspension for high TPI (tracks per inch) hard disk drives is presented. Two reinforced piezoelectric microactuators, placed in parallel between the base plate and the spring beam, are used for the secondary actuation. A stroke of 1.2 ?m at the head was observed when driven by 30 V. The first torsion and the sway mode frequencies are

Yimin Niu; Wei Guo; Guoxiao Guo; Eng Hong Ong; K. K. Sivadasan; Tony Huang

2000-01-01

203

Improved Piezoelectric Loudspeakers And Transducers  

NASA Technical Reports Server (NTRS)

Loudspeakers and related acoustic transducers of improved type feature both light weight and energy efficiency of piezoelectric transducers and mechanical coupling efficiency. Active component of transducer made from wafer of "rainbow" piezoelectric material, ceramic piezoelectric material chemically reduced on one face. Chemical treatment forms wafer into dishlike shallow section of sphere. Both faces then coated with electrically conductive surface layers serving as electrodes. Applications include high-fidelity loudspeakers, and underwater echo ranging devices.

Regan, Curtis Randall; Jalink, Antony; Hellbaum, Richard F.; Rohrbach, Wayne W.

1995-01-01

204

High Temperature Piezoelectric Drill  

NASA Technical Reports Server (NTRS)

Venus is one of the planets in the solar systems that are considered for potential future exploration missions. It has extreme environment where the average temperature is 460 deg C and its ambient pressure is about 90 atm. Since the existing actuation technology cannot maintain functionality under the harsh conditions of Venus, it is a challenge to perform sampling and other tasks that require the use of moving parts. Specifically, the currently available electromagnetic actuators are limited in their ability to produce sufficiently high stroke, torque, or force. In contrast, advances in developing electro-mechanical materials (such as piezoelectric and electrostrictive) have enabled potential actuation capabilities that can be used to support such missions. Taking advantage of these materials, we developed a piezoelectric actuated drill that operates at the temperature range up to 500 deg C and the mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) configuration. The detailed results of our study are presented in this paper

Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom

2012-01-01

205

High temperature piezoelectric drill  

NASA Astrophysics Data System (ADS)

Venus is one of the planets in the solar systems that are considered for potential future exploration missions. It has extreme environment where the average temperature is 460°C and its ambient pressure is about 90 atm. Since the existing actuation technology cannot maintain functionality under the harsh conditions of Venus, it is a challenge to perform sampling and other tasks that require the use of moving parts. Specifically, the currently available electromagnetic actuators are limited in their ability to produce sufficiently high stroke, torque, or force. In contrast, advances in developing electro-mechanical materials (such as piezoelectric and electrostrictive) have enabled potential actuation capabilities that can be used to support such missions. Taking advantage of these materials, we developed a piezoelectric actuated drill that operates at the temperature range up to 500°C and the mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) configuration. The detailed results of our study are presented in this paper.

Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom

2012-04-01

206

Hybrid piezoelectric energy harvesting transducer system  

NASA Technical Reports Server (NTRS)

A hybrid piezoelectric energy harvesting transducer system includes: (a) first and second symmetric, pre-curved piezoelectric elements mounted separately on a frame so that their concave major surfaces are positioned opposite to each other; and (b) a linear piezoelectric element mounted separately on the frame and positioned between the pre-curved piezoelectric elements. The pre-curved piezoelectric elements and the linear piezoelectric element are spaced from one another and communicate with energy harvesting circuitry having contact points on the frame. The hybrid piezoelectric energy harvesting transducer system has a higher electromechanical energy conversion efficiency than any known piezoelectric transducer.

Xu, Tian-Bing (Inventor); Jiang, Xiaoning (Inventor); Su, Ji (Inventor); Rehrig, Paul W. (Inventor); Hackenberger, Wesley S. (Inventor)

2008-01-01

207

PIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGY  

E-print Network

PIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGY PIEZOELECTRIC POWER SCAVENGING OFPIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGYMECHANICAL VIBRATION ENERGY CE 511- Structural

Ervin, Elizabeth K.

208

Piezoelectrically enhanced photocathode  

NASA Technical Reports Server (NTRS)

A photocathode, for generating electrons in response to incident photons in a photodetector, includes a base layer having a first lattice structure and an active layer having a second lattice structure and epitaxially formed on the base layer, the first and second lattice structures being sufficiently different to create a strain in the active layer with a corresponding piezoelectrically induced polarization field in the active layer, the active layer having a band gap energy corresponding to a desired photon energy.

Beach, Robert A. (Inventor); Nikzad, Shouleh (Inventor); Strittmatter, Robert P. (Inventor); Bell, Lloyd Douglas (Inventor)

2009-01-01

209

Modeling piezoelectric actuators  

Microsoft Academic Search

The piezoelectric actuator (PEA) is a well-known device for managing extremely small displacements in the range from 10 pm to 100 ?m. When developing a control system for a piezo-actuated positioning mechanism, the actuator dynamics have to be taken into account. An electromechanical piezo model, based on physical principles, is presented in this paper. In this model, a first-order differential

H. J. M. T. S. Adriaens; W. L. De Koning; R. Banning

2000-01-01

210

Multimaterial piezoelectric fibres  

NASA Astrophysics Data System (ADS)

Fibre materials span a broad range of applications ranging from simple textile yarns to complex modern fibre-optic communication systems. Throughout their history, a key premise has remained essentially unchanged: fibres are static devices, incapable of controllably changing their properties over a wide range of frequencies. A number of approaches to realizing time-dependent variations in fibres have emerged, including refractive index modulation, nonlinear optical mechanisms in silica glass fibres and electroactively modulated polymer fibres. These approaches have been limited primarily because of the inert nature of traditional glassy fibre materials. Here we report the composition of a phase internal to a composite fibre structure that is simultaneously crystalline and non-centrosymmetric. A ferroelectric polymer layer of 30?m thickness is spatially confined and electrically contacted by internal viscous electrodes and encapsulated in an insulating polymer cladding hundreds of micrometres in diameter. The structure is thermally drawn in its entirety from a macroscopic preform, yielding tens of metres of piezoelectric fibre. The fibres show a piezoelectric response and acoustic transduction from kilohertz to megahertz frequencies. A single-fibre electrically driven device containing a high-quality-factor Fabry-Perot optical resonator and a piezoelectric transducer is fabricated and measured.

Egusa, S.; Wang, Z.; Chocat, N.; Ruff, Z. M.; Stolyarov, A. M.; Shemuly, D.; Sorin, F.; Rakich, P. T.; Joannopoulos, J. D.; Fink, Y.

2010-08-01

211

Facilitating NASA's Use of GEIA-STD-0005-1, Performance Standard for Aerospace and High Performance Electronic Systems Containing Lead-Free Solder  

NASA Technical Reports Server (NTRS)

GEIA-STD-0005-1 defines the objectives of, and requirements for, documenting processes that assure customers and regulatory agencies that AHP electronic systems containing lead-free solder, piece parts, and boards will satisfy the applicable requirements for performance, reliability, airworthiness, safety, and certify-ability throughout the specified life of performance. It communicates requirements for a Lead-Free Control Plan (LFCP) to assist suppliers in the development of their own Plans. The Plan documents the Plan Owner's (supplier's) processes, that assure their customer, and all other stakeholders that the Plan owner's products will continue to meet their requirements. The presentation reviews quality assurance requirements traceability and LFCP template instructions.

Plante, Jeannete

2010-01-01

212

A study on (K, Na) NbO3 based multilayer piezoelectric ceramics micro speaker  

NASA Astrophysics Data System (ADS)

A flat panel micro speaker was fabricated from (K, Na) NbO3 (KNN)-based multilayer piezoelectric ceramics by a tape casting and cofiring process using Ag-Pd alloys as an inner electrode. The interface between ceramic and electrode was investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The acoustic response was characterized by a standard audio test system. We found that the micro speaker with dimensions of 23 × 27 × 0.6 mm3, using three layers of 30 ?m thickness KNN-based ceramic, has a high average sound pressure level (SPL) of 87 dB, between 100 Hz-20 kHz under five voltage. This result was even better than that of lead zirconate titanate (PZT)-based ceramics under the same conditions. The experimental results show that the KNN-based multilayer ceramics could be used as lead free piezoelectric micro speakers.

Gao, Renlong; Chu, Xiangcheng; Huan, Yu; Sun, Yiming; Liu, Jiayi; Wang, Xiaohui; Li, Longtu

2014-10-01

213

Structural, microstructural and thermal properties of lead-free bismuth–sodium–barium–titanate piezoceramics synthesized by mechanical alloying  

SciTech Connect

Graphical abstract: Mechano-synthesis of lead-free (Bi{sub 0.5}Na{sub 0.5}){sub 0.94}Ba{sub 0.06}TiO{sub 3} piezoceramics with nanocrystalline/amorphous structure and homogeneous composition: partial transformation of constituents to BNBT, BNT and pyrochlore, amorphous phase formation, mechano-crystallization of the amorphous, pyrochlore-to-perovskite BNBT phase transformation during the process. Display Omitted Highlights: ? Perovskite BNBT powders with homogeneous composition were synthesized by MA. ? Partial transformation of constituents to BNBT, BNT and pyrochlore occurred by MA. ? Formation of an amorphous phase and afterwards its crystallization occurred by MA. ? Pyrochlore-to-perovskite BNBT phase transformation occurred after prolong milling. ? Polymorphic transformations of TiO{sub 2} act as the main alloying impediment during MA. -- Abstract: Bismuth–sodium–barium–titanate piezoceramics with a composition of (Bi{sub 0.5}Na{sub 0.5}){sub 0.94}Ba{sub 0.06}TiO{sub 3} (BNBT) were prepared by mechanical alloying (MA). Structural analysis and phase identification were performed by X-ray diffraction (XRD). Microstructural studies and chemical composition homogeneity were performed by scanning electron microscope (SEM) coupled with energy dispersive X-ray analysis (EDX). Furthermore, thermal properties of the as-milled powders were evaluated by thermogravimetry/differential thermal analysis (TG/DTA). During the initial milling, the constituents were transformed to the perovskite, pyrochlore, and BNT phases; in addition, partial amorphization of the structure appeared during the milling cycle. As MA progressed, transformation of pyrochlore-to-perovskite and crystallization of the amorphous phase occurred and also, the BNBT phase was significantly developed. It was found that the MA process has the ability to synthesize the BNBT powders with a submicron particle size, regular morphology, and uniform elemental distribution.

Amini, Rasool, E-mail: amini@sutech.ac.ir [Department of Materials Science and Engineering, Shiraz University of Technology, 71557-13876 Shiraz (Iran, Islamic Republic of)] [Department of Materials Science and Engineering, Shiraz University of Technology, 71557-13876 Shiraz (Iran, Islamic Republic of); Ghazanfari, Mohammad Reza; Alizadeh, Morteza; Ardakani, Hamed Ahmadi [Department of Materials Science and Engineering, Shiraz University of Technology, 71557-13876 Shiraz (Iran, Islamic Republic of)] [Department of Materials Science and Engineering, Shiraz University of Technology, 71557-13876 Shiraz (Iran, Islamic Republic of); Ghaffari, Mohammad [Department of Electrical and Electronics Engineering, UNAM—National Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey)] [Department of Electrical and Electronics Engineering, UNAM—National Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey)

2013-02-15

214

Piezoelectric dispenser based on a piezoelectric-metal-cavity actuator.  

PubMed

A piezoelectric dispenser has been fabricated based on the idea of a piezoelectric-metal-cavity (PMC) actuator. The PMC actuator consists of a metal ring sandwiched between two identical piezoelectric unimorphs. The radial contraction of the piezoelectric ceramic is converted into a flextensional motion of the unimorph, causing a large flexural displacement in the center part of the actuator. With the PMC actuator as a fluid chamber, the large flexural actuation can be used to produce the displacement needed to eject fluid. By applying an appropriate voltage to the piezoelectric unimorphs, a drop-on-demand ejection of ink or water can be achieved. The efficiency of fluid ejection can be enhanced after installing a valve in the fluid chamber. With the simple PMC structure, the dispenser can be operated with a low driving voltage of 12-15 V. PMID:19655984

Lam, K H; Sun, C L; Kwok, K W; Chan, H L W

2009-07-01

215

Piezoelectric dispenser based on a piezoelectric-metal-cavity actuator  

NASA Astrophysics Data System (ADS)

A piezoelectric dispenser has been fabricated based on the idea of a piezoelectric-metal-cavity (PMC) actuator. The PMC actuator consists of a metal ring sandwiched between two identical piezoelectric unimorphs. The radial contraction of the piezoelectric ceramic is converted into a flextensional motion of the unimorph, causing a large flexural displacement in the center part of the actuator. With the PMC actuator as a fluid chamber, the large flexural actuation can be used to produce the displacement needed to eject fluid. By applying an appropriate voltage to the piezoelectric unimorphs, a drop-on-demand ejection of ink or water can be achieved. The efficiency of fluid ejection can be enhanced after installing a valve in the fluid chamber. With the simple PMC structure, the dispenser can be operated with a low driving voltage of 12-15 V.

Lam, K. H.; Sun, C. L.; Kwok, K. W.; Chan, H. L. W.

2009-07-01

216

Piezoelectric actuators for dynamic applications  

Microsoft Academic Search

The main advantages of piezoelectrical actuators are their high resolution in motion and their excellent dynamic behavior. Especially the very short response times of solid state actuators presents new opportunities in developing high dynamical systems with unsurpassable characteristics. New concepts of piezoelectrically driven microoptical devices, e.g. optical fiber switches, intensity modulators and choppers, can be developed. Very compact systems with

Peter Buecker; Bernt Goetz; Thomas Martin

1998-01-01

217

478 IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES, VOL. 31, NO. 2, JUNE 2008 Reliability and Failure Analysis of Lead-Free  

E-print Network

478 IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES, VOL. 31, NO. 2, JUNE 2008 to certify the safety of an electronic package during the manufacturing and shipping processes. But recently with chemical compositions of 95.5Sn4.0Ag0.5Cu and 63Sn37Pb. It was found that the lead-free solder has a longer

Kim, Yong Jung

218

Coaxing graphene to be piezoelectric  

NASA Astrophysics Data System (ADS)

Several exotic characteristics and properties have made graphene a well-studied material from both a basic science viewpoint as well as tantalizing applications ranging from nanoelectronics, gas separation membranes to ultracapacitors. Graphene, however, is non-piezoelectric. This is obvious when graphene is in its metallic or semi-metallic state. However, even when graphene is in dielectric form—which can be engineered through porosity or by using nanoribbons—graphene is non-piezoelectric due to its centrosymmetric crystal structure. Using quantum mechanical calculations, we show that merely by creating holes of the right symmetry, graphene can be coaxed to act as a piezoelectric. We find that certain specifically tailored porous graphene sheets can "acquire" piezoelectricity coefficient that is nearly 72% of the well-known piezoelectric (quartz) or 36% of boron nitride nanotubes.

Chandratre, Swapnil; Sharma, Pradeep

2012-01-01

219

High-Temperature Piezoelectric Sensing  

PubMed Central

Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. PMID:24361928

Jiang, Xiaoning; Kim, Kyungrim; Zhang, Shujun; Johnson, Joseph; Salazar, Giovanni

2014-01-01

220

Performance analysis of piezoelectric cantilever bending actuators  

Microsoft Academic Search

Bimorph and unimorph are two typical bending mode actuators, either consisting two piezoelectric layers or one piezoelectric layer and one elastic layer. In the case of bimorph actuator, when an electric field is applied to the piezoelectric layers, one layer expands while the other contract along length direction, producing a pure bending deformation. In unimorph actuator, when piezoelectric layer is

Qing-Ming Wang; L. Eric Cross

1998-01-01

221

Design Requirements for Amorphous Piezoelectric Polymers  

NASA Technical Reports Server (NTRS)

An overview of the piezoelectric activity in amorphous piezoelectric polymers is presented. The criteria required to render a polymer piezoelectric are discussed. Although piezoelectricity is a coupling between mechanical and electrical properties, most research has concentrated on the electrical properties of potentially piezoelectric polymers. In this work, we present comparative mechanical data as a function of temperature and offer a summary of polarization and electromechanical properties for each of the polymers considered.

Ounaies, Z.; Young, J. A.; Harrison, J. S.

1999-01-01

222

Radial Field Piezoelectric Diaphragms  

NASA Technical Reports Server (NTRS)

A series of active piezoelectric diaphragms were fabricated and patterned with several geometrically defined Inter-Circulating Electrodes "ICE" and Interdigitated Ring Electrodes "ICE". When a voltage potential is applied to the electrodes, the result is a radially distributed electric field that mechanically strains the piezoceramic along the Z-axis (perpendicular to the applied electric field). Unlike other piezoelectric bender actuators, these Radial Field Diaphragms (RFDs) strain concentrically yet afford high displacements (several times that of the equivalent Unimorph) while maintaining a constant circumference. One of the more intriguing aspects is that the radial strain field reverses itself along the radius of the RFD while the tangential strain remains relatively constant. The result is a Z-deflection that has a conical profile. This paper covers the fabrication and characterization of the 5 cm. (2 in.) diaphragms as a function of poling field strength, ceramic thickness, electrode type and line spacing, as well as the surface topography, the resulting strain field and displacement as a function of applied voltage at low frequencies. The unique features of these RFDs include the ability to be clamped about their perimeter with little or no change in displacement, the environmentally insulated packaging, and a highly repeatable fabrication process that uses commodity materials.

Bryant, R. G.; Effinger, R. T., IV; Copeland, B. M., Jr.

2002-01-01

223

Ferroelastic Characterization of Piezoelectrics  

NASA Astrophysics Data System (ADS)

The elastic deformation behavior of an isotropic material is governed by Young's modulus Y and Poisson's ratio ?. Knowledge of the Young's modulus, for instance, is necessary to split the total deformation S i measured under load stress T i into elastic S {/i el} and "plastic" S {/i pl} strain contributions S_i = S_i^el + S_i^pl = {T_i over Y} + S_i^pl , where Y is not necessarily a constant, but may depend on the amount of nonelastic strains, as will be shown later. The methods for the determination of the Young's moduli, well-known from conventional ceramics and also applicable to unpoled piezoelectric materials, are much more complicated for nonisotropic materials due to the tensorial character of the modulus and the special electric boundary conditions [1]. The conditions of a constant electrical field, E z ? E 3 = const, or a constant dielectric displacement, D z ? E 3 = const, influence the elastic properties. This effect may be illustrated for a uniaxial stress state with T x ? T 1 ? 0 exclusively. In the case of a piezoelectric material, we are interested in the components D_3 = d_{31}T_1 + \\varepsilon_{33}^T E_3 .

Fett, T.

224

Radiation tolerance of piezoelectric bulk single-crystal aluminum nitride.  

PubMed

For practical use in harsh radiation environments, we pose selection criteria for piezoelectric materials for non-destructive evaluation (NDE) and material characterization. Using these criteria, piezoelectric aluminum nitride is shown to be an excellent candidate. The results of tests on an aluminum-nitride- based transducer operating in a nuclear reactor are also presented. We demonstrate the tolerance of single-crystal piezoelectric aluminum nitride after fast and thermal neutron fluences of 1.85 x 10(18) neutron/cm(2) and 5.8 x 10(18) neutron/ cm(2), respectively, and a gamma dose of 26.8 MGy. The radiation hardness of AlN is most evident from the unaltered piezoelectric coefficient d33, which measured 5.5 pC/N after a fast and thermal neutron exposure in a nuclear reactor core for over 120 MWh, in agreement with the published literature value. The results offer potential for improving reactor safety and furthering the understanding of radiation effects on materials by enabling structural health monitoring and NDE in spite of the high levels of radiation and high temperatures, which are known to destroy typical commercial ultrasonic transducers. PMID:24960710

Parks, David A; Tittmann, Bernhard R

2014-07-01

225

Aeroservoelastic DAP missile fin development. [directionally attached piezoelectric actuator  

NASA Technical Reports Server (NTRS)

The development of an active aeroservoelastic missile fin using directionally attached piezoelectric (DAP) actuator elements is detailed. Several different types of actuator elements are examined, including piezoelectric polymers, piezoelectric fiber composites, and conventionally attached piezoelectric (CAP) and DAP elements. These actuator elements are bonded to the substrate of a torque plate. The root of the torque plate is attached to a fuselage hard point or folding pivot. The tip of the plate is bonded to an aerodynamic shell which undergoes a pitch change as the plate twists. The design procedures used on the plate are discussed. A comparison of the various actuator element shows that DAP elements provide the highest deflections with the highest torsional stiffness. A torque plate was constructed from 0.2032 mm thick DAP elements bonded to a 0.127 mm thick AISI 1010 steel substrate. The torque plate produced static twist deflections in excess of +/- 3 deg. An aerodynamic shell with a modified NACA 0012 profile was added to the torque plate. This fin was tested in a wind tunnel at speeds up to 50 ms/sec. The static deflection of the fin was predicted to within 6 percent of the experimental data.

Barrett, Ron

1993-01-01

226

Radiation tolerance of piezoelectric bulk single-crystal aluminum nitride  

SciTech Connect

For practical use in harsh radiation environments, we pose selection criteria for piezoelectric materials for nondestructive evaluation (NDE) and material characterization. Using these criteria, piezoelectric aluminum nitride is shown to be an excellent candidate. The results of tests on an aluminumnitride-based transducer operating in a nuclear reactor are also presented. We demonstrate the tolerance of single-crystal piezoelectric aluminum nitride after fast and thermal neutron fluences of 1.85 × 1018 neutron/cm2 and 5.8 × 1018 neutron/cm2, respectively, and a gamma dose of 26.8 MGy. The radiation hardness of AlN is most evident from the unaltered piezoelectric coefficient d33, which measured 5.5 pC/N after a fast and thermal neutron exposure in a nuclear reactor core for over 120 MWh, in agreement with the published literature value. The results offer potential for improving reactor safety and furthering the understanding of radiation effects on materials by enabling structural health monitoring and NDE in spite of the high levels of radiation and high temperatures, which are known to destroy typical commercial ultrasonic transducers.

David A. Parks; Bernhard R. Tittmann

2014-07-01

227

Precision piezoelectric stepping motor using piezoelectric torsional actuator  

NASA Astrophysics Data System (ADS)

This paper deals with a newly developed piezoelectric motor that generates precise stepping motion using a piezoelectric torsional actuator and a pair of one-way clutch bearings. The torsional actuator consists of a piezoelectric cylinder that produces rotation motion invoking shear mode of piezoelectric materials and a torsion bar that magnifies the rotation angle produced from the piezoelectric cylinder. Inner one-way clutch bearing is fit on the torsion bar and outer bearing is mounted outside of the inner bearing such that when the torsion bar rotates in one direction, the inner bearing moves together while the outer one slips. When the torsion bar rotates in opposite direction, the inner bearing slips against the torsion bar while the outer bearing locks the inner bearing so as to accumulate the rotation angle. Because the elaborate piezoelectric torsional actuator functions as the driving source at high frequency, a precise step motion with high speed can be produced. The optimum condition for driving the motor is investigated in terms of excitation frequency, electrical impedance and the location of the bearing set. The rotation speed and torque of the motor is investigated, and 350 rpm and 0.19mNm torque are observed in maximum.

Kang, Byung-Woo; Kim, Jaehwan; Cheong, ChaeCheon; Yang, Bo-Won

2001-03-01

228

Characterization of organic gunshot residues in lead-free ammunition using a new sample collection device for liquid chromatography-quadrupole time-of-flight mass spectrometry.  

PubMed

The identification of characteristic organic gunshot residues (OGSR) provides conclusive evidence in the elucidation of elemental profiles when lead-free ammunition is fired. OGSR also prevents false negatives. Toward this aim, a quick and efficient method based on liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF) was developed to detect and identify 18 gunpowder additives in gunshot residues (GSR). The unequivocal identification of target analytes was assured by using MS/MS mode. Swabs were compared with home-modified tape lift supports covered with a PTFE layer to determine the better sampling technique. The modified tape lift provided better extraction recoveries and enabled the analysis of inorganic and organic GSR simultaneously. The developed method was applied to the analysis of GSR from four different lead-free ammunitions. Diphenylamine and its nitrated degradation products and centralites were identified in all samples, providing strong evidence of GSR. PMID:25481775

Benito, Sandra; Abrego, Zuriñe; Sánchez, Alicia; Unceta, Nora; Goicolea, M Aranzazu; Barrio, Ramón J

2015-01-01

229

Low electric-field driven ultrahigh electrostrains in Sb-substituted (Na,K)NbO3 lead-free ferroelectric ceramics  

NASA Astrophysics Data System (ADS)

Lead-free (Na0.52K0.48)(Nb1-ySby)O3 (NKNSy) ferroelectric ceramics were reported to exhibit an ultrahigh electrostrain (dynamic d33* (=S/E) of 800-1100 pm/V) in a relatively low driving electric field range (1-4 kV/mm). As evidenced by in-situ synchrotron x-ray diffraction and dielectric measurements, the mechanism of generating large strains was ascribed to both the low-field induced reversible rhombohedral-monoclinic phase transition (1-2 kV/mm) and the enhanced domain switching (2-4 kV/mm) owing to the normal to relaxor phase transformation, which contribute to ˜62% and ˜38% of the total strain, respectively. The results indicate that the NKNSy compositions would have excellent potentials for applications of lead-free actuator ceramics.

Fu, Jian; Zuo, Ruzhong; Qi, He; Zhang, Chen; Li, Jingfeng; Li, Longtu

2014-12-01

230

Piezoelectric One-Way Remote  

NSDL National Science Digital Library

In this activity, learners construct a device out of a piezoelectric igniter, like those used as barbecue lighters. Learners use the device to remotely start current flowing in a simple series circuit containing a small electric fan.

Rathjen, Don

2004-01-01

231

Piezoelectric MEMS for energy harvesting  

E-print Network

Piezoelectric microelectromechanical systems (MEMS) have been proven to be an attractive technology for harvesting small magnitudes of energy from ambient vibrations. This technology promises to eliminate the need for ...

Kim, Sang-Gook

232

A piezoelectrically actuated ball valve  

NASA Technical Reports Server (NTRS)

Bimorph strip composed of two layers of poled piezoelectric ceramic material closes and opens valve. Strip performs like capacitator, allowing initial inrush of current when valve is energized and then only small leakage current flows as valve remains energized.

Erwin, L. R.; Schwartz, H. W.; Teitelbaum, B. R.

1972-01-01

233

Effect of ENIG deposition on the failure mechanisms of thermomechanically loaded lead-free 2nd level interconnections in LTCC\\/PWB assemblies  

Microsoft Academic Search

Purpose – The purpose of this paper is to investigate the effect of electroless NiAu (ENIG) deposition on the failure mechanisms and characteristic lifetimes of three different non-collapsible lead-free 2nd level interconnections in low-temperature co-fired ceramic (LTCC)\\/printed wiring board (PWB) assemblies. Design\\/methodology\\/approach – Five LTCC module\\/PWB assemblies were fabricated and exposed to a temperature cycling test over a ?40 to

O. Nousiainen; T. Kangasvieri; K. Kautio; R. Rautioaho; J. Vähäkangas

2010-01-01

234

Effects of Ga, Al, Ag, and Ce multi-additions on the wetting characteristics of Sn9Zn lead-free solder  

Microsoft Academic Search

An orthogonal method was used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the wetting characteristics\\u000a of Sn-9Zn lead-free solders by wetting balance method. The results show that the optimal loading of Ga, Al, Ag, and Ce was\\u000a 0.2 wt.%, 0.002 wt.%, 0.25 wt.%, and 0.15 wt.%, respectively. Intermetallic compounds (IMCs) formed at the interface between

Hui Wang; Songbai Xue; Feng Zhao; Wenxue Chen

2009-01-01

235

Formation and morphology of the intermetallic compounds formed at the 91Sn–8.55Zn–0.45Al lead-free solder alloy\\/Cu interface  

Microsoft Academic Search

Formation and morphology of the intermetallic compounds (IMCs) formed at the 91Sn–8.55Zn–0.45Al lead-free solder alloy\\/Cu interface has been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED). The XRD analysis indicates that the ?-Cu5Zn8 IMC is found at the solder\\/Cu interface in the as-wetted sample. When heat treated at 423K for 100

Moo-Chin Wang; Shan-Pu Yu; Tao-Chih Chang; Min-Hsiung Hon

2005-01-01

236

Piezoelectric Rotary Tube Motor  

NASA Technical Reports Server (NTRS)

A custom rotary SQUIGGLE(Registered TradeMark) motor has been developed that sets new benchmarks for small motor size, high position resolution, and high torque without gear reduction. Its capabilities cannot be achieved with conventional electromagnetic motors. It consists of piezoelectric plates mounted on a square flexible tube. The plates are actuated via voltage waveforms 90 out of phase at the resonant frequency of the device to create rotary motion. The motors were incorporated into a two-axis postioner that was designed for fiber-fed spectroscopy for ground-based and space-based projects. The positioner enables large-scale celestial object surveys to take place in a practical amount of time.

Fisher, Charles D.; Badescu, Mircea; Braun, David F.; Culhane, Robert

2011-01-01

237

The Propagation of Rayleigh Waves in Layered Piezoelectric Structures with Viscosity  

E-print Network

The Propagation of Rayleigh Waves in Layered Piezoelectric Structures with Viscosity Jinxiang Shen propagation in resonators with viscosity of materials for solutions which can be used for the estimations of the viscosity, which usually is not the ideal value we can obtain from material testing. Not hard to imagine

Wang, Ji

238

Design and testing of a hybrid polymeric electrostrictive\\/piezoelectric beam with bang–bang control  

Microsoft Academic Search

Electrostrictive materials, hard ceramics and soft polymers, have been used as precision actuators in many engineering applications. This study is to examine bang–bang control performance of a hybrid Plexiglas beam laminated with polymeric electrostrictive (RTV 270) actuator and piezoelectric polyvinylidene fluoride (PVDF) sensor layers using both analytical and experimental techniques. Material characteristics are calibrated via static testing first; a hybrid

H. S. Tzou; W. K. Chai

2007-01-01

239

Piezoelectric activity in Perovskite ferroelectric crystals.  

PubMed

Perovskite ferroelectrics (PFs) have been the dominant piezoelectric materials for various electromechanical applications, such as ultrasonic transducers, sensors, and actuators, to name a few. In this review article, the development of PF crystals is introduced, focusing on the crystal growth and piezoelectric activity. The critical factors responsible for the high piezoelectric activity of PFs (i.e., phase transition, monoclinic phase, domain size, relaxor component, dopants, and piezoelectric anisotropy) are surveyed and discussed. A general picture of the present understanding on the high piezoelectricity of PFs is described. At the end of this review, potential approaches to further improve the piezoelectricity of PFs are proposed. PMID:25585387

Li, Fei; Wang, Linghang; Jin, Li; Lin, Dabin; Li, Jinglei; Li, Zhenrong; Xu, Zhuo; Zhang, Shujun

2015-01-01

240

Piezoelectrically Initiated Pyrotechnic Igniter  

NASA Technical Reports Server (NTRS)

This innovation consists of a pyrotechnic initiator and piezoelectric initiation system. The device will be capable of being initiated mechanically; resisting initiation by EMF, RF, and EMI (electromagnetic field, radio frequency, and electromagnetic interference, respectively); and initiating in water environments and space environments. Current devices of this nature are initiated by the mechanical action of a firing pin against a primer. Primers historically are prone to failure. These failures are commonly known as misfires or hang-fires. In many cases, the primer shows the dent where the firing pin struck the primer, but the primer failed to fire. In devices such as "T" handles, which are commonly used to initiate the blowout of canopies, loss of function of the device may result in loss of crew. In devices such as flares or smoke generators, failure can result in failure to spot a downed pilot. The piezoelectrically initiated ignition system consists of a pyrotechnic device that plugs into a mechanical system (activator), which on activation, generates a high-voltage spark. The activator, when released, will strike a stack of electrically linked piezo crystals, generating a high-voltage, low-amperage current that is then conducted to the pyro-initiator. Within the initiator, an electrode releases a spark that passes through a pyrotechnic first-fire mixture, causing it to combust. The combustion of the first-fire initiates a primary pyrotechnic or explosive powder. If used in a "T" handle, the primary would ramp the speed of burn up to the speed of sound, generating a shock wave that would cause a high explosive to go "high order." In a flare or smoke generator, the secondary would produce the heat necessary to ignite the pyrotechnic mixture. The piezo activator subsystem is redundant in that a second stack of crystals would be struck at the same time with the same activation force, doubling the probability of a first strike spark generation. If the first activation fails to ignite, the device is capable of multiple attempts. Another unique aspect is in the design of the pyrotechnic device. There is an electrode that aids the generation of a directed spark and the use of a conductive matrix to support the first-fire material so that the spark will penetrate to the second electrode.

Quince, Asia; Dutton, Maureen; Hicks, Robert; Burnham, Karen

2013-01-01

241

Water-Induced Degradation in Lead Zinc Niobate Lead Zirconate Titanate Soft Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

Water-induced degradation of lead zinc niobate-lead zirconate titanate (Pb(Zn1/3Nb2/3)O3-Pb(ZrTi)O3) soft piezoelectric ceramics is studied using electrochemical hydrogen charging, in which the silver electrodes of the piezoelectric ceramics constitute a cathode in 0.01-M NaOH solution to evolve hydrogen by electrolysis of water. It is found that with the increasing hydrogen charging time, the resonance impedance increases, the difference between the resonance frequency and the anti-resonance frequency decreases, the spontaneous polarization, the remanent polarization and the piezoelectric coefficient d33 decrease. The degradation behaviour of the soft piezoelectric ceramics can be explained to hydrogen incorporating into the lattice and forming hydroxy (OH-) bonds in the perovskite structure, which prevents the Ti ions from switching and increases the coercive field Ec. The degradation characteristics of the soft piezoelectric ceramics are quite different from that of lead zirconate titanate hard piezoelectric ceramics.

Jiang, Xiang-Ping; Chen, Wan-Ping; Peng, Zhi; Zeng, Min; Chan-Wang, Li-Hua; Yin, Qing-Rui

2005-05-01

242

Wideband piezoelectric pressure transducer  

NASA Astrophysics Data System (ADS)

A piezoelectric pressure transducer for pressures of up to 100 MPa was developed, with an operating frequency range from 100 Hz to 1 MHz on the electrical side - sufficiently wide to reproduce pressure profiles of arc discharges with microsecond rise times and millisecond fall times. The sensing element is a disk of TsTS-19 piezoceramic material, 1 mm thick and 5 mm in diameter. It is thermally and electrically insulated from the arc plasma by a compound transmission rod consisting of two quartz crystals 5 mm in diameter and freely sliding inside a teflon sleeve. The 50 mm long waveguide for absorbing acoustic vibrations and thus separating the valid signal from the reflected one consists of brass wires acoustically insulated with epoxy resin and encapsulated into a textolite sleeve with epoxy resin at the other end. A copper housing shields the transducer from electromagnetic interference. The transducer output signal passes through a matching circuit and then a high-impedance voltage divider to a differential amplifier, the latter being shunted by a stabilizing low 1 Mohm resistance at the input. A special feature of this transducer is low-frequency compensation by means of a corrective RC-circuit. After calibration of oscillograms, the transducer has a sensitivity of 1 V/MPa over the 10(-2) to 10 MPa range. Its resolution corresponds to the 2 microsecond maximum rise time of its output signal, with the sensing element located at the end of a shock tube.

Godonyuk, V. A.; Zhuravlev, B. V.; Shedko, I. P.

1986-02-01

243

Integrated wireless piezoelectric sensors  

NASA Astrophysics Data System (ADS)

Piezoelectric sensor arrays and sensor networks have been suggested as a means to monitor the integrity of composite structures throughout the service life for instance of an aircraft. Complex sensor systems will require significant additional expenditures with respect to cabling and electronics, with the added weight and effort possibly outweighing any benefits. Sensor positions in remote locations of an aircraft will often necessitate accessibility to these locations for maintenance purposes. For these reasons wireless, integrated sensors have recently become an object of increasing interest. Within the framework of a feasibility study various aspects of integrated wireless sensor system were investigated in detail. Particular emphasis was thereby laid on issues that are essential form a practical point of view, but that have not been discussed in the literature extensively. As a starting point a trade-off study between different sensor network configurations was conducted, form passive, remotely queried senors without power supply to fully functional active sensor pads with integrated power supply and electronics. Various concepts for the on-board energy supply of remotely queried sensor pads were studied and a comparison between rechargeable, and single-use batteries was performed. The suitability of different electronic components for integration into carbon fiber composites was investigated with particular emphasis on their survivability under typical temperature cycles experienced in autoclave runs. Finally, a crackwire sensor as an example of a passive remotely queried sensor system was pursued further in order to show the feasibility of such a wireless system for composite health monitoring purposes.

Ihler, Elmar; Zaglauer, Helmut W.; Herold-Schmidt, Ursula; Dittrich, Kay W.; Wiesbeck, Werner

2000-06-01

244

Design of Multi-phase Piezoelectric Actuators  

Microsoft Academic Search

A new multi-objective topology optimization method is proposed in this study for systematic design of multi-phase piezoelectric actuators. The actuator under consideration is composed of a compliant host structure equipped with piezoelectric elements, where the host structure serves as a compliant amplifier to enlarge the small stroke output generated by the actuation force of piezoelectric materials. In the context of

Zhen Luo; Wei Gao; Chongmin Song

2010-01-01

245

Power Electronics Design Choice for Piezoelectric Microrobots  

E-print Network

. INTRODUCTION Piezoelectric actuators, both stack and cantilever type, have become increasingly popular srinath ronf} @eecs.berkeley.edu Abstract-- Piezoelectric actuators are advantageous for mi- crorobots due of integration. However, the main disadvantage of either stack or cantilever piezoelectric actuators are the high

Fearing, Ron

246

Polymer Piezoelectric Transducers for Ultrasonic NDE  

NASA Technical Reports Server (NTRS)

Piezoelectric polymers are associated with a low noise and inherent damping that makes them very effective receivers as well as broadband transmitters for high frequencies tasks. This paper reviews polymer piezoelectric materials, the origin of their piezoelectric behavior and their applications to ultrasonic NDE.

Bar-Cohen, Yoseph; Xue, Tianji; Lih, Shyh-Shiuh

1996-01-01

247

Electro-caloric effect in (Ba1-xCax)(Zr0.05Ti0.95)O3: A lead-free ferroelectric material  

NASA Astrophysics Data System (ADS)

Electro-caloric effect in lead-free (Ba1-xCax)(Zr0.05Ti0.95)O3 ferroelectric ceramics has been studied for x = 0.05, 0.08, and 0.10. The electro-caloric coefficient as high as 0.253 K mm/kV has been obtained near tetragonal-to-cubic phase transition for x = 0.08. This value is nearly the same as observed in lead-based ferroelectric materials. The higher value of electro-caloric coefficient at x = 0.08 is attributed to the higher polarization flexibility.

Singh, Gurvinderjit; Tiwari, V. S.; Gupta, P. K.

2013-11-01

248

Effects of Ga, Al, Ag, and Ce multi-additions on the properties of Sn–9Zn lead-free solder  

Microsoft Academic Search

Wetting balance method is used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the solderability of Sn–9Zn\\u000a lead-free solders, results show that the optimal addition amounts of Ga, Al, Ag, and Ce is 0.2, 0.002, 0.25, and 0.15 wt%\\u000a respectively. The surface property of Sn–9Zn–0.2Ga–0.002Al–0.25Ag–0.15Ce solder is studied by X-ray photoelectron spectroscopy\\u000a and auger electron spectroscopy

Hui Wang; Songbai Xue; Feng Zhao; Wenxue Chen

2010-01-01

249

Kinetics of intermetallic compound formation at 91Sn–8.55Zn–0.45Al lead-free solder alloy\\/Cu interface  

Microsoft Academic Search

The kinetics of intermetallic compounds (IMCs) formation at the 91Sn–8.55Zn–0.45Al lead-free solder alloy\\/Cu substrate interface during soldering and subsequent aging have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM) and electron diffraction (ED). From the XRD results, ?-Cu5Zn8 and Cu6Sn5 are found in the eutectic 91Sn–8.55Zn–0.45Al solder alloy\\/copper interface, but

Moo-Chin Wang; Shan-Pu Yu; Tao-Chih Chang; Min-Hsiung Hon

2004-01-01

250

Gamma Irradiation Effects on the Lead-Free Bi2O3-B2O3-SiO2 Glasses  

NASA Astrophysics Data System (ADS)

In the present work, gamma irradiation effects on lead-free Bi2O3-B2O3-SiO2 heavy metal oxide glasses are investigated. By doping Ti4+ ions, irradiation resistance of glasses is improved, especially in the case of the higher radiation dose. However, traditionally used stabilizing agent Ce4+ ions exert a negative effect on glasses by increasing the value of irradiation induced absorption coefficient, ?. This is maybe due to the different role of Ce4+ ions in the present Bi2O3-B2O3-SiO2 glass structure...

Baccaro, S.; Cemmi, A.; Wang, T.; Chen, G.

2012-08-01

251

Size effects in tin-based lead-free solder joints: Kinetics of bond formation and mechanical characteristics  

NASA Astrophysics Data System (ADS)

Continuous miniaturization of microelectronic interconnects demands smaller joints with comparable microstructural and structural sizes. As the size of joints become smaller, the volume of intermetallics (IMCs) becomes comparable with the joint size. As a result, the kinetics of bond formation changes and the types and thicknesses of IMC phases that form within the constrained region of the bond varies. This dissertation focuses on investigating combination effects of process parameters and size on kinetics of bond formation, resulting microstructure and the mechanical properties of joints that are formed under structurally constrained conditions. An experiment is designed where several process parameters such as time of bonding, temperature, and pressure, and bond thickness as structural chracteristic, are varied at multiple levels. The experiment is then implemented on the process. Scanning electron microscope (SEM) is then utilized to determine the bond thickness, IMC phases and their thicknesses, and morphology of the bonds. Electron backscatter diffraction (EBSD) is used to determine the grain size in different regions, including the bulk solder, and different IMC phases. Physics-based analytical models have been developed for growth kinetics of IMC compounds and are verified using the experimental results. Nanoindentation is used to determine the mechanical behavior of IMC phases in joints in different scales. Four-point bending notched multilayer specimen and four-point bending technique were used to determine fracture toughness of the bonds containing IMCs. Analytical modeling of peeling and shear stresses and fracture toughness in tri-layer four-point bend specimen containing intermetallic layer was developed and was verified and validated using finite element simulation and experimental results. The experiment is used in conjunction with the model to calculate and verify the fracture toughness of Cu6Sn5 IMC materials. As expected two different IMC phases, ?-phase (Cu6Sn 5) and epsilon-phase (Cu3Sn), were found in almost all the cases regardless of the process parameters and size levels. The physics-based analytical model was successfully able to capture the governing mechanisms of IMC growth: chemical reaction controlled and diffusion-controlled. Examination of microstructures of solder joints of different sizes revealed the size of the solder joint has no effect on the type of IMCs formed during the process. Joint size, however, affected the thickness of IMC layers significantly. IMC layers formed in the solder joints of smaller sizes were found to be thicker than those in the solder joints of larger sizes. The growth rate constants and activation energies of Cu3Sn IMC layer were also reported and related to joint thickness. In an effort to optimize the EBSD imaging in the multi-layer configuration, an improved specimen preparation technique and optimum software parameters were determined. Nanoindentation results show that size effects play a major role on the mechanical properties of micro-scale solder joints. Smaller joints show higher Young's modulus, hardness, and yield strength and lower work hardening exponents comparing to thicker joints. To obtain the stress concentration factors in a multilayer specimen with IMC layer as bonding material, a four-point bending notched configuration was used. The analytical solutions developed for peeling and shear stresses in notched structure were used to evaluate the stresses at IMC interface layers. Results were in good agreement with the finite-element simulation. The values of interfacial stresses were utilized in obtaining fracture toughness of the IMC material. (Abstract shortened by UMI.)

Abdelhadi, Ousama Mohamed Omer

252

Hydrogen Materials Compatibility in Piezoelectrics  

NASA Astrophysics Data System (ADS)

Hydrogen materials compatibility is an important materials science issue for hydrogen storage and delivery in hydrogen vehicle technology and infrastructure and to a lesser degree the microelectronics industry where hydrogen passivation is required. Piezoelectrics are one such material. They are used in direct injection hydrogen internal combustion engines (H2ICE) as actuators but tend to foul rapidly in high pressure hydrogen. Ferroelectric random access memory (FERAM) also suffers similar degradation issues. We present high pressure hydrogen absorption and diffusion findings for PZT and BaTiO3 piezoelectric materials. Data is based on quasi-elastic neutron (QENS) scattering and elastic recoil detection analysis (ERDA).

Alvine, Kyle; Pitman, Stan; Henager, Charles; Shutthanandan, Vaithiyalingam; Brown, Craig; Tyagi, Madhu; Jenkins, Tim; Udovic, Terry

2010-03-01

253

Piezoelectric Driver for Incremental Motion  

NASA Technical Reports Server (NTRS)

Vibrating device containing two piezoelectric ceramic slabs acts as mechanical driver. Eventually substitutes for small continuous or stepping electric motors of slow to moderate speeds. Piezoelectric driver simple in construction, requires no precise dimensions, inexpensive to make, and needs no lubrication. Not damaged by stalling or overloads and safe for use in explosive atmospheres; Motion controllable in micron-size increments, and holds position when power turned off. Potential applications as positioner or mover. Used to position instrument pointers, antennas, or solar panels; to focus lenses; or operate tuners, recording instruments, or valves.

Bruman, Joseph R.

1987-01-01

254

Piezoelectric materials used in underwater acoustic transducers  

SciTech Connect

Piezoelectric materials have been used in underwater acoustic transducers for nearly a century. In this paper, we reviewed four different types of piezoelectric materials: piezoelectric ceramics, single crystals, composites, and polymers, which are widely used in underwater acoustic transducers nowadays. Piezoelectric ceramics are the most dominant material type and are used as a single-phase material or one of the end members in composites. Piezoelectric single crystals offer outstanding electromechanical response but are limited by their manufacturing cost. Piezoelectric polymers provide excellent acoustic impedance matching and transducer fabrication flexibility although their piezoelectric properties are not as good as ceramics and single crystals. Composites combined the merits of ceramics and polymers and are receiving increased attention. The typical structure and electromechanical properties of each type of materials are introduced and discussed with respect to underwater acoustic transducer applications. Their advantages and disadvantages are summarized. Some of the critical design considerations when developing underwater acoustic transducers with these materials are also touched upon.

Li, Huidong; Deng, Zhiqun; Carlson, Thomas J.

2012-07-07

255

Standard hardness conversion tables for metals relationship among brinell hardness, vickers hardness, rockwell hardness, superficial hardness, knoop hardness, and scleroscope hardness  

E-print Network

1.1 Conversion Table 1 presents data in the Rockwell C hardness range on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, Knoop hardness, and Scleroscope hardness of non-austenitic steels including carbon, alloy, and tool steels in the as-forged, annealed, normalized, and quenched and tempered conditions provided that they are homogeneous. 1.2 Conversion Table 2 presents data in the Rockwell B hardness range on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, Knoop hardness, and Scleroscope hardness of non-austenitic steels including carbon, alloy, and tool steels in the as-forged, annealed, normalized, and quenched and tempered conditions provided that they are homogeneous. 1.3 Conversion Table 3 presents data on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, and Knoop hardness of nickel and high-nickel alloys (nickel content o...

American Society for Testing and Materials. Philadelphia

2007-01-01

256

Energy conversion in piezoelectric superlattices  

Microsoft Academic Search

A superlattice is formed in a piezoelectric substrate by intervallic polarizing oppositely along one direction. Wave propagation in this structure is studied with plane-wave expansion method. The polariton behavior in the superlattice is obtained by solving Newton's equations of motion and Maxwell's equations simultaneously. Significant coupling between mechanical and electromagnetic energy occurs in the vicinity of the center of the

Yuan-Fang Chou; Ming-Yi Yang

2007-01-01

257

Thin Film Piezoelectrics for MEMS  

Microsoft Academic Search

Thin film piezoelectric materials offer a number of advantages in microelectromechanical systems (MEMS), due to the large motions that can be generated, often with low hysteresis, the high available energy densities, as well as high sensitivity sensors with wide dynamic ranges, and low power requirements. This paper reviews the literature in this field, with an emphasis on the factors that

S. Trolier-McKinstry; P. Muralt

2004-01-01

258

Cylindrical Piezoelectric Fiber Composite Actuators  

NASA Technical Reports Server (NTRS)

The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

2008-01-01

259

Piezoelectric measurement of laser power  

DOEpatents

A method for measuring the energy of individual laser pulses or a series of laser pulses by reading the output of a piezoelectric (PZ) transducer which has received a known fraction of the total laser pulse beam. An apparatus is disclosed that reduces the incident energy on the PZ transducer by means of a beam splitter placed in the beam of the laser pulses.

Deason, Vance A. (Idaho Falls, ID); Johnson, John A. (Idaho Falls, ID); Telschow, Kenneth L. (Idaho Falls, ID)

1991-01-01

260

Vacuum mounting for piezoelectric transducers  

NASA Technical Reports Server (NTRS)

Special housing couples piezoelectric transducers to nonporous surfaces for ultrasonic or acoustic-emission testing. Device, while providing sound isolation on flat or nonflat surfaces, can be attached and detached quickly. Vacuum sealing mechanism eliminates need for permanent or semipermanent bonds, viscous coupling liquids, weights, magnets, tape, or springs ordinarily used.

Tiede, D. A.

1977-01-01

261

Circuit for Driving Piezoelectric Transducers  

NASA Technical Reports Server (NTRS)

The figure schematically depicts an oscillator circuit for driving a piezoelectric transducer to excite vibrations in a mechanical structure. The circuit was designed and built to satisfy application-specific requirements to drive a selected one of 16 such transducers at a regulated amplitude and frequency chosen to optimize the amount of work performed by the transducer and to compensate for both (1) temporal variations of the resonance frequency and damping time of each transducer and (2) initially unknown differences among the resonance frequencies and damping times of different transducers. In other words, the circuit is designed to adjust itself to optimize the performance of whichever transducer is selected at any given time. The basic design concept may be adaptable to other applications that involve the use of piezoelectric transducers in ultrasonic cleaners and other apparatuses in which high-frequency mechanical drives are utilized. This circuit includes three resistor-capacitor networks that, together with the selected piezoelectric transducer, constitute a band-pass filter having a peak response at a frequency of about 2 kHz, which is approximately the resonance frequency of the piezoelectric transducers. Gain for generating oscillations is provided by a power hybrid operational amplifier (U1). A junction field-effect transistor (Q1) in combination with a resistor (R4) is used as a voltage-variable resistor to control the magnitude of the oscillation. The voltage-variable resistor is part of a feedback control loop: Part of the output of the oscillator is rectified and filtered for use as a slow negative feedback to the gate of Q1 to keep the output amplitude constant. The response of this control loop is much slower than 2 kHz and, therefore, does not introduce significant distortion of the oscillator output, which is a fairly clean sine wave. The positive AC feedback needed to sustain oscillations is derived from sampling the current through the piezoelectric transducer. This positive AC feedback, in combination with the slow feedback to the voltage-variable resistors, causes the overall loop gain to be just large enough to keep the oscillator running. The positive feedback loop includes two 16-channel multiplexers, which are not shown in the figure. One multiplexer is used to select the desired piezoelectric transducer. The other multiplexer, which is provided for use in the event that there are significant differences among the damping times of the 16 piezoelectric transducers, facilitates changing the value of one of the resistors in the positive-feedback loop to accommodate the damping time of the selected transducer.

Randall, David P.; Chapsky, Jacob

2009-01-01

262

A measurement method for piezoelectric material properties under longitudinal compressive stress--a compression test method for thin piezoelectric materials  

Microsoft Academic Search

We introduce a new compression test method for piezoelectric materials to investigate changes in piezoelectric properties under the compressive stress condition. Until now, compression tests of piezoelectric materials have been generally conducted using bulky piezoelectric ceramics and pressure block. The conventional method using the pressure block for thin piezoelectric patches, which are used in unimorph or bimorph actuators, is prone

Lae-Hyong Kang; Dae-Oen Lee; Jae-Hung Han

2011-01-01

263

Virus-based piezoelectric energy generation  

NASA Astrophysics Data System (ADS)

Piezoelectric materials can convert mechanical energy into electrical energy, and piezoelectric devices made of a variety of inorganic materials and organic polymers have been demonstrated. However, synthesizing such materials often requires toxic starting compounds, harsh conditions and/or complex procedures. Previously, it was shown that hierarchically organized natural materials such as bones, collagen fibrils and peptide nanotubes can display piezoelectric properties. Here, we demonstrate that the piezoelectric and liquid-crystalline properties of M13 bacteriophage (phage) can be used to generate electrical energy. Using piezoresponse force microscopy, we characterize the structure-dependent piezoelectric properties of the phage at the molecular level. We then show that self-assembled thin films of phage can exhibit piezoelectric strengths of up to 7.8 pm V-1. We also demonstrate that it is possible to modulate the dipole strength of the phage, hence tuning the piezoelectric response, by genetically engineering the major coat proteins of the phage. Finally, we develop a phage-based piezoelectric generator that produces up to 6 nA of current and 400 mV of potential and use it to operate a liquid-crystal display. Because biotechnology techniques enable large-scale production of genetically modified phages, phage-based piezoelectric materials potentially offer a simple and environmentally friendly approach to piezoelectric energy generation.

Lee, Byung Yang; Zhang, Jinxing; Zueger, Chris; Chung, Woo-Jae; Yoo, So Young; Wang, Eddie; Meyer, Joel; Ramesh, Ramamoorthy; Lee, Seung-Wuk

2012-06-01

264

Microstructure and Sn crystal orientation evolution in Sn-3.5Ag lead-free solders in high temperature packaging applications  

SciTech Connect

Understanding the reliability of eutectic Sn-3.5Ag lead-free solders in high temperature packaging applications is of significant interest in power electronics for the next generation electric grid. Large area (2.5mm 2.5mm) Sn-3.5Ag solder joints between silicon dies and direct bonded copper substrates were thermally cycled between 5 C and 200 C. Sn crystal orientation and microstructure evolution during thermal cycling were characterized by electron backscatter diffraction (EBSD) in scanning electron microscope (SEM). Comparisons are made between observed initial texture and microstructure and its evolution during thermal cycling. Gradual lattice rotation and grain boundary misorientation evolution suggested the continuous recrystallization mechanism. Recrystallization behavior was correlated with dislocation slip activities.

Zhou, Bite [ORNL; Muralidharan, Govindarajan [ORNL; Kurumaddali, Nalini Kanth [ORNL; Parish, Chad M [ORNL; Leslie, Dr Scott [Powerex Inc; Bieler, T. R. [Michigan State University, East Lansing

2014-01-01

265

Relaxorlike dielectric dynamics in the lead-free K0.5Na0.5NbO3-SrZrO3 ceramic system  

NASA Astrophysics Data System (ADS)

We have detected a typical relaxor/glasslike dielectric response in the derived lead-free (1-x)K0.5Na0.5NbO3-(x)SrZrO3 ceramic system. In the compositional range 0.10?x?0.33, where solid solubility was observed, the system exhibits a broad dispersive dielectric maximum, a Vogel-Fulcher temperature dependence of the characteristic relaxation frequency, and a paraelectric-to-glass crossover in the temperature dependence of the dielectric nonlinearity. As the relatively high values of the dielectric constant, exceeding 5000 in the x =0.15 compound, are only weakly dependent on the frequency in the range of 20 Hz-1 MHz, and, furthermore, the history-dependent effects play only a minor role in comparison to some widely used lead-based relaxors, this environmentally friendly system seems to be very promising for a variety of applications.

Bobnar, Vid; Holc, Janez; Hrovat, Marko; Kosec, Marija

2007-04-01

266

Piezoelectric cantilevers optimization for vibration energy harvesting  

NASA Astrophysics Data System (ADS)

Vibration-based piezoelectric energy harvesters through the conversion of vibration energy to electrical energy has gained increasing attention over the past decade because of the reduced power requirements of small electronic components, especially in industrial condition monitoring applications where sensors may be embedded in machines. The structure parameters of cantilevered piezoelectric energy harvesters are of importance to maximize the output power in accordance with the characteristics of the ambient vibrations. Therefore, a piezoelectric cantilevers optimization method using finite element analysis and SPICE is proposed. This paper models piezoelectric cantilever using Hamilton principle and extracts the vibration modal parameters to establish the circuit model in SPICE. The numerical analysis is addressed to study the effect of parameters. Finally, the optimization analysis and experiment are carried out. The results verify that the optimized cantilevered piezoelectric energy harvesters can produce a 56V peak open-circuit voltage, and that the proposed method is suitable for optimization design of piezoelectric energy harvester.

Cao, Junyi; Zhou, Shengxi; Ren, Xiaolong; Cao, Binggang

2012-04-01

267

Piezoelectric cantilevers optimization for vibration energy harvesting  

NASA Astrophysics Data System (ADS)

Vibration-based piezoelectric energy harvesters through the conversion of vibration energy to electrical energy has gained increasing attention over the past decade because of the reduced power requirements of small electronic components, especially in industrial condition monitoring applications where sensors may be embedded in machines. The structure parameters of cantilevered piezoelectric energy harvesters are of importance to maximize the output power in accordance with the characteristics of the ambient vibrations. Therefore, a piezoelectric cantilevers optimization method using finite element analysis and SPICE is proposed. This paper models piezoelectric cantilever using Hamilton principle and extracts the vibration modal parameters to establish the circuit model in SPICE. The numerical analysis is addressed to study the effect of parameters. Finally, the optimization analysis and experiment are carried out. The results verify that the optimized cantilevered piezoelectric energy harvesters can produce a 56V peak open-circuit voltage, and that the proposed method is suitable for optimization design of piezoelectric energy harvester.

Cao, Junyi; Zhou, Shengxi; Ren, Xiaolong; Cao, Binggang

2011-11-01

268

Piezoelectric Power Requirements for Active Vibration Control  

NASA Technical Reports Server (NTRS)

This paper presents a method for predicting the power consumption of piezoelectric actuators utilized for active vibration control. Analytical developments and experimental tests show that the maximum power required to control a structure using surface-bonded piezoelectric actuators is independent of the dynamics between the piezoelectric actuator and the host structure. The results demonstrate that for a perfectly-controlled system, the power consumption is a function of the quantity and type of piezoelectric actuators and the voltage and frequency of the control law output signal. Furthermore, as control effectiveness decreases, the power consumption of the piezoelectric actuators decreases. In addition, experimental results revealed a non-linear behavior in the material properties of piezoelectric actuators. The material non- linearity displayed a significant increase in capacitance with an increase in excitation voltage. Tests show that if the non-linearity of the capacitance was accounted for, a conservative estimate of the power can easily be determined.

Brennan, Matthew C.; McGowan, Anna-Maria Rivas

1997-01-01

269

Optical piezoelectric transducer for nano-ultrasonics  

Microsoft Academic Search

Piezoelectric semiconductor strained layers can be treated as piezoelectric transducers to generate nanometer-wavelength and THz-frequency acoustic waves. The mechanism of nano-acoustic wave (NAW) generation in strained piezoelectric layers, induced by femtosecond optical pulses, can be modeled by a macroscopic elastic continuum theory. The optical absorption change of the strained layers modulated by NAW through quantum-confined Franz-Keldysh (QCFK) effects allows optical

Kung-Hsuan Lin; Gia-Wei Chern; Cheng-Ta Yu; Tzu-Ming Liu; Chang-Chi Pan; Guan-Ting Chen; Jen-Inn Chyi; Sheng-Wen Huang; Pai-Chi Li; Chi-Kuang Sun

2005-01-01

270

Stepping Piezoelectric Actuators Based on APAs  

Microsoft Academic Search

Stepping Piezoelectric Actuators (SPA) are new small long-stroke linear piezoelectric motors for micro\\/nano positioning applications benefiting of the advantages and the heritage of the APA. SPA is formed of only 4 parts: the well-established Amplified Piezoelectric Actuators (APA), a front mass, a clamp and a rod. SPA operates by accumulation of small steps, using inertial mode, impact forces and stick-slip

F. Claeyssen; A. Ducamp; F. Barillot; R. Le Letty; T. Porchez; O. Sosnicki; C. Belly

271

Additional Drive Circuitry for Piezoelectric Screw Motors  

NASA Technical Reports Server (NTRS)

Modules of additional drive circuitry have been developed to enhance the functionality of a family of commercially available positioning motors (Picomotor . or equivalent) that provide linear motion controllable, in principle, to within increments .30 nm. A motor of this type includes a piezoelectric actuator that turns a screw. Unlike traditional piezoelectrically actuated mechanisms, a motor of this type does not rely on the piezoelectric transducer to hold position: the screw does not turn except when the drive signal is applied to the actuator.

Smythe, Robert; Palmer, Dean; Gursel, Yekta; Reder, Leonard; Savedra, Raymond

2004-01-01

272

A Piezoelectric Cryogenic Heat Switch  

NASA Technical Reports Server (NTRS)

We have measured the thermal conductance of a mechanical heat switch actuated by a piezoelectric positioner, the PZHS (PieZo electric Heat Switch), at cryogenic temperatures. The thermal conductance of the PZHS was measured between 4 K and 10 K, and on/off conductance ratios greater than 100 were achieved when the positioner applied its maximum force of 8 N. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an optimized PZHS.

Jahromi, Amir E.; Sullivan, Dan F.

2014-01-01

273

Fracture mechanics for piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

We Study cracks either in piezoelectrics, or on interfaces between piezoelectrics and other materials such as metal electrodes or polymer matrices. The projected applications include ferroelectric actuators operating statically or cyclically, over the major portion of the samples, in the linear regime of the constitutive curve, but the elevated field around defects causes the materials to undergo hysteresis locally. The fracture mechanics viewpoint is adopted—that is, except for a region localized at the crack tip, the materials are taken to be linearly piezoelectric. The problem thus breaks into two subproblems: (i) determining the macroscopic field regarding the crack tip as a physically structureless point, and (ii) considering the hysteresis and other irreversible processes near the crack tip at a relevant microscopic level. The first Subproblem, which prompts a phenomenological fracture theory, receives a thorough investigation in this paper. Griffith's energy accounting is extended to include energy change due to both deformation and polarization. Four modes of square root singularities are identified at the tip of a crack in a homogeneous piezoelectric. A new type of singularity is discovered around interface crack tips. Specifically, the singularities in general form two pairs: r {1}/{2}±i? and r {1}/{2}±i? , where ?. and k are real numbers depending on the constitutive constants. Also solved is a class of boundary value problems involving many cracks on the interface between half-spaces. Fracture mechanics are established for ferroelectric ceramics under smallscale hysteresis conditions, which facilitates the experimental study of fracture resistance and fatigue crack growth under combined mechanical and electrical loading. Both poled and unpoled fcrroelectrie ceramics are discussed.

Suo, Z.; Kuo, C.-M.; Barnett, D. M.; Willis, J. R.

1992-05-01

274

Kinetic ceramics piezoelectric hydraulic pumps  

NASA Astrophysics Data System (ADS)

This paper discusses the development and testing of two Piezoelectrically driven Hydraulic Pumps (PHP2 & PHP3) utilizing low cost discrete multilayer piezoelectric actuators and low cost structural components. New valve technologies were developed utilizing reed and MEMS valves. Structural optimization was performed to decrease weight and volume. The PHP3 design extracts power from a PZT material with high efficiency despite impedance mismatch between the piezoelectric actuator and fluid by utilizing a hydraulic pendulum energy recovery technique. Hydraulic power of 168 watts can be developed with a pump mass of under 1lb. Flow rate of 2300 cc/min free flow has been demonstrated as well as output pressure greater than 200 bar in the stalled condition. The result of the effort is practical solid state conversion of electrical energy into a useable hydraulic source for actuation systems without having normal rotational wear components. The PHP2 pump was used to power the hydraulic primary flight controls in a RPV technology demonstrator flight tested in November 2006.

O'Neill, Conal; Burchfield, John

2007-04-01

275

Interdigitated single crystal piezoelectric actuator  

NASA Astrophysics Data System (ADS)

Piezoelectric actuators are used as critical units or elements of various electromechanical systems. In this paper, we propose a novel piezoelectric actuator cantilever with double interdigitated electrode patterns. We investigate the possibility of both flexural and longitudinal actuation capabilities of the double interdigitated electrode patterns applied on a piezoelectric cantilever structure. This monomorph structure has the interdigitated electrode patterns top and bottom. The structure also uses single-crystal relaxor ferroelectric material. We separately pattern interdigitated electrodes on the top and bottom surfaces of a PMN-PT single crystal cantilever beam. The interdigitated electrode design on a surface of the cantilever beam results in an electric field gradient. This results in a flapping actuation. Previously, we showed that the vertical field component induced by the interdigitated electrode is dominant over the horizontal component under input bias voltage, and generates subsequent contraction of the surface along the axial direction after poling. In this paper, we show that a contraction on the top surface and an elongation on the bottom leads to upward bending motion because of the differential contraction along the thickness induced by the interdigitated electrode pattern. Similarly, an equivalent elongation on the top and bottom surfaces is shown to lead to longitudinal motion in the double interdigitated electrode sample.

Hong, Yong K.; Moon, Kee S.

2005-12-01

276

Phase transitional behavior and piezoelectric properties of (Na0.5K0.5)NbO3-LiNbO3 ceramics  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric ceramics (1-x)(Na0.5K0.5)NbO3-xLiNbO3 {[Lix(Na0.5K0.5)1-x]NbO3} (x=0.04-0.20) have been synthesized by an ordinary sintering technique. The materials with perovskite structure is orthorhombic phase at x ?0.05 and becomes tetragonal phase at x ?0.07, a phase K3Li2Nb5O15 with tetragonal tungsten bronze structure begins to appear at x =0.08 and becomes dominant with increasing the content of LiNbO3. A morphotropic phase boundary between orthorhombic and tetragonal phases is found in the composition range 0.05piezoelectric and electromechanical properties are enhanced for compositions near the morphotropic phase boundary. Piezoelectric constant d33 values reach 200-235pC/N. Electromechanical coefficients of the planar mode and the thickness mode reach 38%-44% and 44%-48%, respectively. The Curie temperatures (TC) of [Lix(Na0.5K0.5)1-x]NbO3 (x=0.04-0.20) are in the range of 452-510°C, at least 100°C higher than that of conventional Pb(Zr ,Ti)O3. Our results show that [Lix(Na0.5K0.5)1-x]NbO3 is a good lead-free high-temperature piezoelectric ceramic.

Guo, Yiping; Kakimoto, Ken-ichi; Ohsato, Hitoshi

2004-11-01

277

Piezoelectric properties of high Curie temperature barium titanate-bismuth perovskite-type oxide system ceramics  

NASA Astrophysics Data System (ADS)

Barium titanate (BaTiO3, BT)—bismuth magnesium titanium oxide [Bi(Mg0.5Ti0.5)O3, BMT] system ceramics were prepared in an ambient atmosphere in order to increase the Curie temperature (Tc) of BT above 132 °C. A single perovskite phase was observed for BT-BMT ceramics with BMT compositions less than 50 mol %, and their relative densities were greater than 94%. Synchrotron measured x-ray diffraction patterns revealed that all the cations in the ceramics were homogeneously distributed. The temperature dependence of the dielectric properties revealed that the BT-BMT system ceramics exhibited relaxorlike characteristics with a dielectric maximum temperature as high as 360 °C for the 0.5BT-0.5BMT ceramic. The apparent piezoelectric constant (d?) was 60 pC/N for the 0.4BT-0.6BMT ceramic. Based upon these results, the BT-BMT system shows potential as a new type of lead-free material for high Tc piezoelectric applications.

Wada, Satoshi; Yamato, Keisuke; Pulpan, Petr; Kumada, Nobuhiro; Lee, Bong-Yeon; Iijima, Takashi; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

2010-11-01

278

A novel drum piezoelectric-actuator  

Microsoft Academic Search

This paper presents a large displacement, piezoelectric-metal structure actuator, named the piezoelectric drum actuator. The drum actuator consists of a short, thick-walled steel cylinder sandwiched by two thin composite disks, which are fabricated from a brass disk bonded with a piezoceramic disk. The piezoceramic disk, which is polarized in its thickness direction, has a large diameter thickness ratio, producing a

C. L. Sun; K. H. Lam; H. L. W. Chan; X.-Z. Zhao; C. L. Choy

2006-01-01

279

Fractal GPS antenna design on piezoelectric substrate  

Microsoft Academic Search

This paper presents a study of fractal GPS antenna design on piezoelectric substrate. The antenna size is reduced by using piezoelectric materials with high dielectric constant and the fractal structure in antenna design. The desired high effective dielectric constant can be obtained by the special arrangement of the ground. The Koch fractal structure is employed in antenna design. With the

Tzu-Chun Tang; Cheng-Han Tsai; Ken-Huang Lin; Yu-Tung Huang; Chi-Yun Chen

2010-01-01

280

Size optimization of conical piezoelectric energy harvesters  

NASA Astrophysics Data System (ADS)

The optimal design of piezoelectric patches on a piezoelectric conical energy harvester is presented in this study. Based on the equivalent voltage source model, the power of the resistance load is derived firstly. The origin location of the piezoelectric patch is set at the peak points of the modal voltage. The piezoelectric patch is in the region formed by the zero lines where the modal voltage is zero. The location of the peak points and the zero lines are determined by the spatial distribution of the modal voltage and the open-circuit voltage. Three parameters are chosen to locate the piezoelectric patch, i.e. the circumferential width, the length from the origin to the minor end and the length from the origin to the major end. Solving the extremum of the power equation with respect to the three parameters yields the optimal size of the piezoelectric patch. Case studies are given to evaluate the power of the optimal piezoelectric energy harvester. The results indicate that with the origin located at the optimal location, the power of resistance load firstly increases with the width and the lengths until the maximum and then decreases. The optimal width of the piezoelectric patch is 75% of the half-wave length for all of the evaluated modes.

Li, H.; Hu, S. D.; Tzou, H. S.

2015-01-01

281

Optimal Materials Selection for Bimaterial Piezoelectric Microactuators  

Microsoft Academic Search

Piezoelectric actuation is one of the commonly employed actuation schemes in microsystems. This paper focuses on identifying and ranking promising active material\\/substrate combinations for bimaterial piezoelectric (BPE) microactuators based on their performance. The mechanics of BPE structures following simple beam theory assumptions available in the literature are applied to evolve critical performance metrics which govern the materials selection process. Contours

Prasanna Srinivasan; S. Mark Spearing

2008-01-01

282

Experiments to Demonstrate Piezoelectric and Pyroelectric Effects  

ERIC Educational Resources Information Center

Piezoelectric and pyroelectric materials are used in many current applications. The purpose of this paper is to explain the basic properties of pyroelectric and piezoelectric effects and demonstrate them in simple experiments. Pyroelectricity is presented on lead zirconium titanate (PZT) ceramics as an electric charge generated by the temperature…

Erhart, Jirí

2013-01-01

283

Comparison of drive amplifier for piezoelectric actuators  

Microsoft Academic Search

The power requirements imposed on the amplifier by piezoelectric actuators in both open and closed loop vibration suppression control systems is discussed. We consider a two-degree-of-freedom mechanical system driven by a piezoelectric stack for the purpose of analyzing power flow and power dissipation. A state space model for this system that includes the electrical input and output variables of the

Douglas K. Lindner; Nikola Vujic; Donald J. Leo

2001-01-01

284

Comment on "Piezoelectricity under Hydrostatic Pressure"  

NASA Astrophysics Data System (ADS)

It is shown that the special termination of the atoms on (111) surfaces of zinc-blende crystals cannot lead to the "hydrostatic piezoelectric effect" proposed by Woo. The present results are a special case of a more general proof given elsewhere and agree with the traditional bulk theory of piezoelectricity.

Martin, Richard M.

1972-12-01

285

Advanced piezoelectric–ferroelectric stack actuator  

Microsoft Academic Search

A conceptual design and an operational algorithm for an advanced piezoelectric–ferroelectric stack actuator are developed. The actuator takes advantage of the large strains due to the domain-switching phenomenon and utilizes the nonlinear range of response of the ferroelectric material. As a result, the proposed conceptual design allows for deformations that are considerably larger than the ones obtained using conventional piezoelectric

Uri Kushnir; Oded Rabinovitch

2009-01-01

286

Epitaxial piezoelectric thick film heterostructures on silicon  

Microsoft Academic Search

The significantly higher dielectric permittivity, piezoelectric coefficients and electromechanical coupling coefficients of single crystal relaxor ferroelectrics make them very attractive for medical ultrasound transducers and microelectromechanical systems (MEMS) applications. The potential impact of thin-film relaxor ferroelectrics in integrated actuators and sensor on silicon has stimulated research on the growth and characterization of epitaxial piezoelectric thin films. We have fabricated heterostructures

Dong Min Kim

2004-01-01

287

Piezoelectric composites for sensor and actuator applications  

Microsoft Academic Search

In the last 25 years, piezoelectric ceramic-polymer composites have been conceptualized, prototyped, fabricated, and implemented in an array of applications encompassing medical imaging and military missions, among others. A detailed snapshot of the materials used, and a detailed account of the major innovative methods developed in making various piezoelectric ceramic-polymer composites are presented. The salient aspects of processing of such

E. Koray Akdogan; Mehdi Allahverdi; Ahmad Safari

2005-01-01

288

Plucked piezoelectric bimorphs for energy harvesting applications  

Microsoft Academic Search

The modern drive towards mobility and wireless devices is motivating intense research in energy harvesting (EH) technologies. In an effort to reduce the battery burden of people, we are investigating a novel piezoelectric wearable energy harvester. As piezoelectric EH is significantly more effective at high frequencies, in opposition to the characteristically low-frequency human activities, we propose the use of an

Michele Pozzi; Meiling Zhu

2011-01-01

289

The effect of Ag content on the formation of Ag3Sn plates in Sn-Ag-Cu lead-free solder  

NASA Astrophysics Data System (ADS)

The formation of Ag3Sn plates in the Sn-Ag-Cu lead-free solder joints for two different Ag content solder balls was investigated in wafer level chip scale packages (WLCSPs). After an appropriate surface mount technology reflow process on a printed circuit board, samples were subjected to 150°C high-temperature storage (HTS), 1,000 h aging, or 1,000 cycles thermal cycling test (TCT). Sequentially, the cross-sectional analysis was scrutinized using a scanning electron microscope/energy dispersive spectrometer (SEM/EDX) to observe the metallurgical evolution of the amount of the Ag3Sn plates at the interface and the solder bulk itself. Pull and shear tests were also performed on samples. It was found that the interfacial intermetallic compound (IMC) thickness, the overall IMC area, and the numbers of Ag3Sn plates increase with increasing HTS and TCT cycles. The amount of large Ag3Sn plates found in the Sn-4.0Ag-0.5 Cu solder balls is much greater than that found in the Sn-2.6Ag-0.5Cu solder balls; however, no significant difference was found in the joint strength between two different Ag content solder joints.

Chiang, Huann-Wu; Chang, Kenndy; Chen, Jun-Yuan

2006-12-01

290

Bipolar electro-caloric effect in SrxBa(1-x)Nb2O6 lead-free ferroelectric single crystal  

NASA Astrophysics Data System (ADS)

Here we report the anomalous electro-caloric effect (ECE) observed in lead-free SrxBa(1-x)Nb2O6 (x=0.50 , 0.61 and 0.75) ferroelectric single crystals. Temperature-dependent hysteresis measurement revealed that the spontaneous polarization of SrxBa(1-x)Nb2O6 single crystals with all the compositions under investigation decreases with a decrease in the temperature below the temperature of the dielectric maxima (T_{\\max}) . As a consequence, these crystals exhibited negative electro-caloric effect at lower temperature along with the usual positive ECE above T_{\\max} . The EC coefficient (\\xi) obtained near T_{\\max} is 0.21, 0.43 and 0.28 K mm/kV for x=0.50 , 0.61 and 0.75 samples, respectively. The maximum values of \\xi in the negative ECE region are -1.4, -0.81 and -0.44\\ \\text{K mm/kV} for 50SBN, 61SBN and 75SBN, respectively.

Bhaumik, Indranil; Ganesamoorthy, S.; Bhatt, R.; Karnal, A. K.; Gupta, P. K.; Takekawa, S.; Kitamura, K.

2014-08-01

291

Relaxor nature in lead-free Sr{sub 5}LaTi{sub 3}Nb{sub 7}O{sub 30} tetragonal tungsten bronze ceramics  

SciTech Connect

Lead-free tetragonal tungsten bronze Sr{sub 5}LaTi{sub 3}Nb{sub 7}O{sub 30} ceramics were prepared and the correlation of the relaxor nature and crystal structure was studied using dielectric spectroscopy and powder X-ray diffraction. Three dielectric relaxations were observed below the deviation temperature T{sub D}? 330 K. Relaxation I and II followed the Vogel-Fulcher law with the freezing temperatures of 189 K and ?90 K. Low temperature relaxation III, which was first observed in filled tungsten bronze, followed well the Arrhenius law. Dielectric response becomes static below 50 K. Polarization-field (P-E) hysteresis loops were evaluated from 183 K to 298 K. P{sub r} value of 0.41?C/cm{sup 2} was observed at 183 K. Deviation of lattice parameter c from the linear contraction and increasing of tetragonality (c/a ratio) were observed below T{sub D}, reflecting the structure change during the formation of polar nanoregions and the following freezing process. Opposite tendency was observed below 100 K for all the lattice parameters, corresponding to relaxation III. Generally, the main dielectric relaxation I and II were attributed to flipping and breathing of polar nanoregions along c axis, while the concerted rotations of the oxygen octahedra in the ab plane were suggested as the origin of relaxation III.

Li Zhu, Xiao [Department of Materials Science and Engineering, Laboratory of Dielectric Materials, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China) [Department of Materials Science and Engineering, Laboratory of Dielectric Materials, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Department of Materials and Ceramic Engineering, Centre for Research in Ceramics and Composite Materials, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Li, Kun; Qiang Liu, Xiao; Ming Chen, Xiang [Department of Materials Science and Engineering, Laboratory of Dielectric Materials, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China)] [Department of Materials Science and Engineering, Laboratory of Dielectric Materials, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Asif Rafiq, Muhammad [Department of Materials and Ceramic Engineering, Centre for Research in Ceramics and Composite Materials, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)] [Department of Materials and Ceramic Engineering, Centre for Research in Ceramics and Composite Materials, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

2013-09-28

292

The structure and optical properties of lead-free transparent KNLTN-La0.01 ceramics prepared by conventional sintering technique  

NASA Astrophysics Data System (ADS)

(Na0.52K0.44Li0.04)0.97La0.01Ta0.20Nb0.80O3 (KNLTN-La0.01) lead-free subtransparent ceramics was prepared by a conventional sintering technique. The structure and the optical properties of the ceramics were investigated. The room temperature crystallographic indexing revealed the ABO3 perovskite type, tetragonal phase and P4mm point group in the ceramics. The surface and fractured surface SEM micrographs showed a dense microstructure with few micropores in KNLTN-La0.01 ceramics, which was obviously better than for the pure KNLTN ceramics. The refractive indexes of the films were investigated by an ellipsometer and the results show that the KNLTN-La0.01 subtransparent ceramics reveals significant wavelength dependent dispersion. The refractive index ranges from 2.14 to 2.06 with the wavelength increase from 380 nm to 900 nm. The dispersive behavior was analyzed by three parameters of Cauchy dispersion model and the values of the parameters A, B and C are 2.0610±0.0005, 0.0054±0.0003 and 0.00069±0.00004, respectively.

Yang, W. L.; Xiu, H. J.; Xiong, Y. L.; Wang, J.; Yuan, C. X.; Wei, J.; Zhou, Z. X.

2014-12-01

293

Characterization of Stress-Strain Response of Lead-Free Solder Joints Using a Digital Image Correlation Technique and Finite-Element Modeling  

NASA Astrophysics Data System (ADS)

The stress-strain response of miniaturized Sn-Ag-Cu (SAC) lead-free solder joints in the thickness range of 80 ?m to about 1.1 mm was studied. A high-resolution three-dimensional (3D) digital image correlation system was used for in situ measurement of displacement and strain fields in the solder joints during tensile testing. These measurements showed that the localization of plastic strain and stress buildup occurs mainly at the interface of the solder. With increasing solder gap thickness the size of the plastically deformed zone in the solder increases, resulting in transformation of a brittle interfacial fracture to a ductile fracture within the bulk of the solder. The experimental deformation plots of solder joints and strain-rate-dependent tensile tests on bulk solder material were used to establish a new constitutive material model for the solder. This strain-rate- and pressure-dependent material model was implemented in ABAQUS through the user subroutine CREEP. In agreement with the experiments, the finite-element method simulation revealed a pronounced thickness effect leading to higher tensile strength of thinner solder joints.

Khatibi, G.; Lederer, M.; Byrne, E.; Kotas, A. Betzwar; Weiss, B.; Ipser, H.

2013-02-01

294

Applications of piezoelectric materials in oilfield services.  

PubMed

Piezoelectric materials are used in many applications in the oilfield services industry. Four illustrative examples are given in this paper: marine seismic survey, precision pressure measurement, sonic logging-while-drilling, and ultrasonic bore-hole imaging. In marine seismics, piezoelectric hydrophones are deployed on a massive scale in a relatively benign environment. Hence, unit cost and device reliability are major considerations. The remaining three applications take place downhole in a characteristically harsh environment with high temperature and high pressure among other factors. The number of piezoelectric devices involved is generally small but otherwise highly valued. The selection of piezoelectric materials is limited, and the devices have to be engineered to withstand the operating conditions. With the global demand for energy increasing in the foreseeable future, the search for hydrocarbon resources is reaching into deeper and hotter wells. There is, therefore, a continuing and pressing need for high-temperature and high-coupling piezoelectric materials. PMID:23007779

Goujon, Nicolas; Hori, Hiroshi; Liang, Kenneth K; Sinha, Bikash K

2012-09-01

295

Structural observation of piezoelectric inhomogeneity in a mixed-orientation Na0.5Bi0.5TiO3 perovskite thin film  

NASA Astrophysics Data System (ADS)

Thin films of the lead-free ferroelectric Na0.5Bi0.5TiO3 grown on thin-film Pt electrodes supported by SrTiO3 substrates have a complex microstructure consisting of crystalline grains with three distinct major crystallographic orientations. The piezoelectric response measured in spatially separated sub-micron grains using time-resolved synchrotron x-ray microdiffraction is highly inhomogeneous even among grains sharing the same major orientation. The piezoelectric coefficient d33 varies by nearly a factor of two in a series of areas sharing the <001> orientation. The piezoelectric inhomogeneity is linked to the peculiar microstructure of the film, arising from local variations in the stress imposed by surrounding grains with different crystallographic orientations and differing directions of the ferroelectric remnant polarization. A systematic nonlinearity of the piezoelectric strain is observed in applied electric fields with small magnitudes in all regions, consistent with the coexistence of domains of differing polarization direction at zero applied electric field.

Carbone, D.; Pateras, A. I.; Bussone, G.; Evans, P. G.; Cornelius, T. W.; Bousquet, M.; Boulle, A.; Gautier, B.; Duclère, J. R.

2014-12-01

296

Enhanced piezoelectricity in broad composition range and the temperature dependence research of (Ba1-xCax)(Ti0.95Sn0.05)O3 piezoceramics  

NASA Astrophysics Data System (ADS)

BaTiO3-based (Ba1-xCax)(Ti0.95Sn0.05)O3 (x=0-0.07) lead-free piezoceramics were fabricated by a conventional solid state reaction technique. The phase structure and electrical properties of the as-prepared ceramics were researched. The temperature (TO-T) of the orthorhombic-tetragonal phase transition dielectric peak shifts toward lower temperature with increasing Ca content and the Curie temperature (TC) almost does not shift. At room temperature, the polymorphic phase transition (PPT) from the orthorhombic phase to tetragonal phase is jointly identified by the ?r-T curves and XRD patterns. The piezoelectricity of the ceramics is enhanced due to the polymorphic phase transition and the best piezoelectricity is obtained at x=0.02 with d33=464 pC/N and kp=43.1%. The piezoelectricity is enhanced in the broad composition range x=0.01-0.06 with d33>400 pC/N and kp>41% which is beneficial for the industrial production. The temperature aging properties of piezoelectric constant d33, planar electromechanical coupling factor kp, the elastic compliance constant S11E and the radial frequency constant Nd are also researched.

Chen, Mingli; Xu, Zhijun; Chu, Ruiqing; Qiu, Hong; Li, Min; Liu, Yong; Shao, Lin; Ma, Shuai; Ji, Wanbin; Li, Wei; Gong, Shuwen; Li, Guorong

2014-01-01

297

Direct observation of intrinsic piezoelectricity of Pb(Zr,Ti)O{sub 3} by time-resolved x-ray diffraction measurement using single-crystalline films  

SciTech Connect

Lead zirconate titanate, Pb(Zr,Ti)O{sub 3} or PZT, is one of the most widely investigated ferroelectric and piezoelectric materials due to its superior properties. However, the intrinsic properties of PZT have not been directly measured due to the lack of fabrication of single crystals even though a basic understanding of intrinsic properties has been of interest developing lead-free piezoelectric materials. We demonstrated the direct observation of the intrinsic piezoelectric property by means of the detection of electric-field induced crystal lattice distortion of thick Pb(Zr{sub 0.35}Ti{sub 0.65})O{sub 3} single-crystalline films with single polar-axis orientation and negligible residual strain using the time-resolved X-ray diffraction (XRD) together with the polarization response. Consequently, the effective converse piezoelectric response was experimentally revealed; hence, the electrostrictive coefficient, which is the conversion coefficient between the electrical and mechanical response, was determined. The obtained effective electrostrictive coefficient was 5.2–6.3?×?10{sup ?2} m{sup 4}/C{sup 2}, which agrees with theoretical prediction.

Fujisawa, Takashi; Ehara, Yoshitaka; Yasui, Shintaro; Kamo, Takafumi; Funakubo, Hiroshi, E-mail: funakubo@iem.titech.ac.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, J2-1508, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8502 (Japan); Yamada, Tomoaki [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, J2-1508, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8502 (Japan); Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Sakata, Osami [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Japan Synchrotron Radiation Research Institute, SPring-8, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

2014-07-07

298

A piezoelectric cryogenic heat switch.  

PubMed

We have measured the thermal conductance of a mechanical heat switch actuated by a piezoelectric positioner, the PZHS (PieZo electric Heat Switch), at cryogenic temperatures. The thermal conductance of the PZHS was measured between 4 K and 10 K, and on/off conductance ratios of about 100-200 at lowest and highest measures temperature were achieved when the positioner applied its maximum force of 8 N, respectively. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an ideal PZHS. PMID:24985863

Jahromi, Amir E; Sullivan, Dan F

2014-06-01

299

Flutter suppression via piezoelectric actuation  

NASA Technical Reports Server (NTRS)

Experimental flutter results obtained from wind tunnel tests of a two degree of freedom wind tunnel model are presented for the open and closed loop systems. The wind tunnel model is a two degree of freedom system which is actuated by piezoelectric plates configured as bimorphs. The model design was based on finite element structural analyses and flutter analyses. A control law was designed based on a discrete system model; gain feedback of strain measurements was utilized in the control task. The results show a 21 pct. increase in the flutter speed.

Heeg, Jennifer

1991-01-01

300

Low pressure piezoelectric valve design  

NASA Astrophysics Data System (ADS)

In this paper a ball-type valve actuated by a piezoelectric bender is studied. In this valve different parameters are adjustable allowing different operational aspects. The design procedure is economic and easy to test. Some models are developed to allow an optimization of the structure for special requirements. A prototype has been manufactured to verify the models. The measurement procedure is exposed. This design does not allow high tank pressure but, on this basis, a structure where the pressure locks the ball (reverse structure) is possible.

Bernard, Y.; Razek, A.

2012-06-01

301

Tunable nonlinear piezoelectric vibration harvester  

NASA Astrophysics Data System (ADS)

Nonlinear piezoelectric energy harvesting generators can provide a large bandwidth combined with a good resonant power output. However, the frequency response is characterized by a strong hysteresis making a technical use difficult if the hysteresis cannot be compensated. We propose a tuning mechanism that allows both, a compensation of the hysteresis as well as maintaining the optimal work point. The compensation algorithm can reduce the hysteresis to a minimum of only 1.5 Hz and maintain a high energy oscillation in a large frequency window between 53.3 Hz and 74.5 Hz.

Neiss, S.; Goldschmidtboeing, F.; Kroener, M.; Woias, P.

2014-11-01

302

Using Diffusion Bonding in Making Piezoelectric Actuators  

NASA Technical Reports Server (NTRS)

A technique for the fabrication of piezoelectric actuators that generate acceptably large forces and deflections at relatively low applied voltages involves the stacking and diffusion bonding of multiple thin piezoelectric layers coated with film electrodes. The present technique stands in contrast to an older technique in which the layers are bonded chemically, by use of urethane or epoxy agents. The older chemical-bonding technique entails several disadvantages, including the following: It is difficult to apply the bonding agents to the piezoelectric layers. It is difficult to position the layers accurately and without making mistakes. There is a problem of disposal of hazardous urethane and epoxy wastes. The urethane and epoxy agents are nonpiezoelectric materials. As such, they contribute to the thickness of a piezoelectric laminate without contributing to its performance; conversely, for a given total thickness, the performance of the laminate is below that of a unitary piezoelectric plate of the same thickness. The figure depicts some aspects of the fabrication of a laminated piezoelectric actuator by the present diffusion- bonding technique. First, stock sheets of the piezoelectric material are inspected and tested. Next, the hole pattern shown in the figure is punched into the sheets. Alternatively, if the piezoelectric material is not a polymer, then the holes are punched in thermoplastic films. Then both faces of each punched piezoelectric sheet or thermoplastic film are coated with a silver-ink electrode material by use of a silkscreen printer. The electrode and hole patterns are designed for minimal complexity and minimal waste of material. After a final electrical test, all the coated piezoelectric layers (or piezoelectric layers and coated thermoplastic films) are stacked in an alignment jig, which, in turn, is placed in a curved press for the diffusion-bonding process. In this process, the stack is pressed and heated at a specified curing temperature and pressure for a specified curing time. The pressure, temperature, and time depend on the piezoelectric material selected. At the end of the diffusion-bonding process, the resulting laminated piezoelectric actuator is tested to verify the adequacy of the mechanical output as a function of an applied DC voltage.

Sager, Frank E.

2003-01-01

303

Steerable Adaptive Bullet (StAB) piezoelectric flight control system  

NASA Astrophysics Data System (ADS)

This paper outlines a new class of piezoelectric flight control actuators which are specifically intended for use in guided hard-launched munitions from under 5.56mm to 40mm in caliber. In March of 2011, US Pat. 7,898,153 was issued, describing this new class of actuators, how they are mounted, laminated, energized and used to control the flight of a wide variety of munitions. This paper is the technical conference paper companion to the Patent. A Low Net Passive Stiffness (LNPS) Post Buckled Precompressed (PBP) piezoelectric actuator element for a 0.40 caliber body, 0.50 caliber round was built and tested. Aerodynamic modeling of the flight control actuator showed that canard deflections of just +/-1° are more than sufficient to provide full flight control against 99% atmospherics to 2km of range while maintaining just 10cm of dispersion with lethal energy pressure levels upon terminal contact. Supersonic wind tunnel testing was conducted as well as a sweep of axial compression. The LNPS/PBP configuration exhibited an amplification factor of 3.8 while maintaining equivalent corner frequencies in excess of 100 Hz and deflection levels of +/-1°. The paper concludes with a fabrication and assembly cost analysis on a mass production scale.

Barrett, Ron; Barnhart, Ryan; Bramlette, Richard

2012-04-01

304

Data based modeling and control of a dual-stage actuator hard disk drive  

Microsoft Academic Search

A data-based approach is presented for modeling and controller design of a dual-stage servo actuator in a hard disk drive. The servo actuator in this hard disk drive consists of a conventional voice coil motor and a piezo-electrically actuated suspension. A weighted Hankel matrix based real- ization algorithm that uses frequency domain data is applied to estimate a discrete-time model

Uwe Boettcher; Raymond A. de Callafon; Frank E. Talke

2009-01-01

305

Modeling and Control of a Dual Stage Actuator Hard Disk Drive  

Microsoft Academic Search

A data-based approach is presented for modeling and controller design of a dual-stage servo actuator in a hard disk drive. The servo actuator in this hard disk drive consists of a conventional voice coil motor and a piezo-electrically actuated suspension. A weighted Hankel matrix based realization algorithm that uses frequency domain data is applied to estimate a discrete-time model of

Uwe Boettcher; Raymond A. De Callafon; Frank E. Talke

2010-01-01

306

Nucleation and Growth of Cu-Al Intermetallics in Al-Modified Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys  

NASA Astrophysics Data System (ADS)

Lead-free solder alloys Sn-Cu (SC) and Sn-Ag-Cu (SAC) are widely used by the microelectronics industry, but enhanced control of the microstructure is needed to improve solder performance. For such control, nucleation and stability of Cu-Al intermetallic compound (IMC) solidification catalysts were investigated by variation of the Cu (0.7-3.0 wt.%) and Al (0.0-0.4 wt.%) content of SC + Al and SAC + Al alloys, and of SAC + Al ball-grid array (BGA) solder joints. All of the Al-modified alloys produced Cu-Al IMC particles with different morphologies and phases (occasionally non-equilibrium phases). A trend of increasing Cu-Al IMC volume fraction with increasing Al content was established. Because of solidification of non-equilibrium phases in wire alloy structures, differential scanning calorimetry (DSC) experiments revealed delayed, non-equilibrium melting at high temperatures related to quenched-in Cu-Al phases; a final liquidus of 960-1200°C was recorded. During cooling from 1200°C, the DSC samples had the solidification behavior expected from thermodynamic equilibrium calculations. Solidification of the ternary alloys commenced with formation of ternary ? and Cu-Al ? phases at 450-550°C; this was followed by ?-Sn, and, finally, Cu6Sn5 and Cu-Al ?1. Because of the presence of the retained, high-temperature phases in the alloys, particle size and volume fraction of the room temperature Cu-Al IMC phases were observed to increase when the alloy casting temperature was reduced from 1200°C to 800°C, even though both temperatures are above the calculated liquidus temperature of the alloys. Preliminary electron backscatter diffraction results seemed to show Sn grain refinement in the SAC + Al BGA alloy.

Reeve, Kathlene N.; Anderson, Iver E.; Handwerker, Carol A.

2015-01-01

307

Dielectric, piezoelectric and damping properties of novel 2-2 piezoelectric composites  

NASA Astrophysics Data System (ADS)

Here, a strip-shaped 2-2 cement/polymer-based piezoelectric composite was designed and fabricated. The dielectric, piezoelectric and electromechanical coupling properties of the composite were investigated as well as the coupling effects between the thickness and lateral modes of the piezoelectric composites. The dielectric and piezoelectric properties of the composites can be greatly influenced by variations of the piezoelectric ceramic volume fraction and the structural dimensions of the composites. Excellent properties have been achieved for ultrasonic transducer applications in civil engineering monitoring fields, such as large piezoelectric voltage constants, high thickness electromechanical coupling coefficients and low acoustic impedance. The damping property of the composites was especially studied. The maximum damping loss factor of the composites is between 0.28–0.32, and the glass transition temperature is between 55°–66 °C.

Dongyu, Xu; Xin, Cheng; Banerjee, Sourav; Lei, Wang; Shifeng, Huang

2015-02-01

308

Size-dependent effective properties of anisotropic piezoelectric composites with piezoelectric nano-particles  

NASA Astrophysics Data System (ADS)

Based on the electro-elastic surface/interface theory, the size-dependent effective piezoelectric and dielectric coefficients of anisotropic piezoelectric composites that consist of spherically piezoelectric inclusions under a uniform electric field are investigated, and the analytical solutions for the elastic displacement and electric potentials are derived. With consideration of the coupling effects of elasticity, permittivity and piezoelectricity, the effective field method is introduced to derive the effective dielectric and piezoelectric responses in the dilute limit. The numerical examples show that the effective dielectric constant exhibits a significant variation due to the surface/interface effect. The dielectric property of the surface/interface displays greater effect than the piezoelectric property, and the elastic property shows little effect. A comparison with the existing results validates the present approach.

Huang, Ming-Juan; Fang, Xue-Qian; Liu, Jin-Xi; Feng, Wen-Jie; Zhao, Yong-Mao

2015-01-01

309

Development of a ?-shaped actuated suspension for 100-kTPI hard disk drives  

Microsoft Academic Search

A suspension-based piezoelectric microactuator has been developed for dual-stage servo systems in hard disk drives. The suspension is designed to meet the requirements of high recording density, high shock resistance, high productivity, and a load\\/unload structure. This paper describes the structure of the actuator and its mechanical characteristics

Mikio Tokuyama; Toshihiko Shimizu; Hiromitsu Masuda; Shigeo Nakamura; Masao Hanya; Osamu Iriuchijima; Jun Soga

2001-01-01

310

Dual-stage track-following servo design for hard disk drives  

Microsoft Academic Search

Discrete time, 25 KTPI track-following servos were designed for magnetic hard disk drive dual stage actuators using the ?-synthesis methodology. The design methodology was tested on two microactuator models. The first is a model of a piezoelectrically actuated suspension, under development by Hutchinson Technology Incorporated. The second is a model of an electrostatically actuated MEMS microactuator, under development by the

Daniel Hernandez; Sung-Su Park; Roberto Horowitz; Andrew K. Packard

1999-01-01

311

Short seeking control with minimum jerk trajectories for dual actuator hard disk drive systems  

Microsoft Academic Search

This paper is concerned with short seeking control for hard disk drives with a dual actuation servo system consisting of a coarse actuator (voice coil motor, VCM) and a fine actuator (piezoelectric actuator, PZT). Short seeking refers to moving the recording head over a few tracks. The primary elements in short seeking control are the feedback controller, the feedforward controller

Jiagen Ding; Federico Marcassa; Masayoshi Tomizuka

2004-01-01

312

Relation of the external mechanical stress to the properties of piezoelectric materials for energy harvesting  

NASA Astrophysics Data System (ADS)

We investigated the piezoelectric properties and the generation of voltage and power under the mechanical compressive loads for three types of piezoelectric ceramics 0.2Pb(Mg1/3Nb2/3)O3-0.8Pb(Zr0.475Ti0.525)O3 (soft-PZT), 0.1Pb(Mg1/3Sb2/3)O3- 0.9Pb(Zr0.475Ti0.525)O3 (hard-PZT) and [0.675Pb(Mg1/3Nb2/3)O3-0.35PbTiO3]+5 wt% BaTiO3 (textured-PMNT). The piezoelectric d 33 coefficients of all specimens increased with increasing compressive load. The generated voltage and power showed a linear relation and square relation to the applied stress, respectively. These results were larger than those calculated using the simple piezoelectric equation due to the non-linear characteristics of the ceramics, so they were evaluated with a simple model based on a non-linear relation.

Jeong, Soon-Jong; Kim, Min-Soo; Lee, Dae-Su; Song, Jae-Sung; Cho, Kyung-Ho

2013-12-01

313

Novel Piezoelectric-Based Power Supply for Driving Piezoelectric Actuators Designed for Active Vibration Damping Applications  

Microsoft Academic Search

This paper describes a novel step-up DC-AC piezoelectric-based power supply for driving piezoelectric actuators. Piezoelectric actuators have been demonstrated to be very attractive in applications requiring fast response and high actuation force, such as active damping applications. These actuators are commonly installed in self-powered systems (cars, helicopters, aircrafts, satellites, etc.) with limitation in the battery performance, dimensions and maximum weight.

Alfredo Vázquez Carazo; Kenji Uchino

2001-01-01

314

Miniature Piezoelectric Macro-Mass Balance  

NASA Technical Reports Server (NTRS)

Mass balances usually use a strain gauge that requires an impedance measurement and is susceptible to noise and thermal drift. A piezoelectric balance can be used to measure mass directly by monitoring the voltage developed across the piezoelectric balance, which is linear with weight or it can be used in resonance to produce a frequency change proportional to the mass change (see figure). The piezoelectric actuator/balance is swept in frequency through its fundamental resonance. If a small mass is added to the balance, the resonance frequency shifts down in proportion to the mass. By monitoring the frequency shift, the mass can be determined. This design allows for two independent measurements of mass. Additionally, more than one sample can be verified because this invention allows for each sample to be transported away from the measuring device upon completion of the measurement, if required. A piezoelectric actuator, or many piezoelectric actuators, was placed between the collection plate of the sampling system and the support structure. As the sample mass is added to the plate, the piezoelectrics are stressed, causing them to produce a voltage that is proportional to the mass and acceleration. In addition, a change in mass delta m produces a change in the resonance frequency with delta f proportional to delta m. In a microgravity environment, the spacecraft could be accelerated to produce a force on the piezoelectric actuator that would produce a voltage proportional to the mass and acceleration. Alternatively, the acceleration could be used to force the mass on the plate, and the inertial effects of the mass on the plate would produce a shift in the resonance frequency with the change in frequency related to the mass change. Three prototypes of the mass balance mechanism were developed. These macro-mass balances each consist of a solid base and an APA 60 Cedrat flextensional piezoelectric actuator supporting a measuring plate. A similar structure with 3 APA 120 Cedrat flextensional piezoelectric actuators spaced equidistantly at 120 degrees supporting the plate and a softer macro balance with an APA 150 actuator/sensor were developed. These flextensional actuators were chosen because they increase the sensitivity of the actuator to stress, allow the piezoelectric to be pre-stressed, and the piezoelectric element is a stacked multilayer actuator, which has a considerably lower input impedance than a monolithic element that allows for common instruments (e.g., input impedance of 10 megohms) to measure the voltage without rapidly discharging the charge/voltage on the piezoelectric actuator.

Sherrit, Stewart; Trebi-Ollennu, Ashitey; Bonitz, Robert G.; Bar-Cohen, Yoseph

2010-01-01

315

Models and Characterization of Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

Selected literature on the use of linearized constitutive equations and complex piezoelectric coefficients to develop models and characterize materials is presented in brief. One-dimensional models of simple piezoelectric ceramic components are derived using linearized constitutive equations and other fundamental relations to illustrate the procedure used to develop multi-dimensional models. Then, the procedure for building models of multi-layer devices using models of components is illustrated. Models are also used to characterize materials. A method to determine the errors when the ANSI/IEEE Standard method is used to determine real piezoelectric coefficients and methods to characterize non-Standard shapes often used in devices are also presented

Ebenezer, D. D.

2008-07-01

316

A traveling wave piezoelectric beam robot  

NASA Astrophysics Data System (ADS)

In this paper, the operation principles of a traveling wave piezoelectric beam robot are presented. A prototype consisting of an aluminum beam structure, with two non-collocated piezoelectric patches bonded on its surface, was fabricated and tested to demonstrate the generation of a traveling wave on the beam based on the one mode excitation and the two mode excitation operation principles for propulsion. A numerical model was developed and used to study and optimize the generated motion of the piezoelectric beam robot. Experimental characterization of the robot for the two types of operation has been carried out, a comparison between them is made and results are given in this paper.

Hariri, H.; Bernard, Y.; Razek, A.

2014-02-01

317

A piezoelectric pseudo-bimorph actuator  

NASA Astrophysics Data System (ADS)

We report a piezoelectric pseudo-bimorph actuator, which is made of only one single plate with interdigitated electrodes on both sides and polarized alternately in longitudinal direction. Like a bimorph actuator, it can also produce a large bending actuation based on anti-symmetrically longitudinal piezoelectric d33 strain effect under an applied electric field. The presented pseudo-bimorph actuator shows much better temperature stability than conventional piezoelectric bimorph actuators from room temperature to the depolarization temperature of the material due to lacking of interface strain loss.

Shi, Huaduo; Chen, Jianguo; Liu, Guoxi; Xiao, Wenlei; Dong, Shuxiang

2013-06-01

318

Piezoelectric voltage coupled reentrant cavity resonator.  

PubMed

A piezoelectric voltage coupled microwave reentrant cavity has been developed. The central cavity post is bonded to a piezoelectric actuator allowing the voltage control of small post displacements over a high dynamic range. We show that such a cavity can be implemented as a voltage tunable resonator, a transducer for exciting and measuring mechanical modes of the structure, and a transducer for measuring comparative sensitivity of the piezoelectric material. Experiments were conducted at room and cryogenic temperatures with results verified using Finite Element software. PMID:25362432

Carvalho, N C; Fan, Y; Le Floch, J-M; Tobar, M E

2014-10-01

319

Piezoelectric voltage coupled reentrant cavity resonator  

NASA Astrophysics Data System (ADS)

A piezoelectric voltage coupled microwave reentrant cavity has been developed. The central cavity post is bonded to a piezoelectric actuator allowing the voltage control of small post displacements over a high dynamic range. We show that such a cavity can be implemented as a voltage tunable resonator, a transducer for exciting and measuring mechanical modes of the structure, and a transducer for measuring comparative sensitivity of the piezoelectric material. Experiments were conducted at room and cryogenic temperatures with results verified using Finite Element software.

Carvalho, N. C.; Fan, Y.; Le Floch, J.-M.; Tobar, M. E.

2014-10-01

320

Subnanosecond piezoelectric x-ray switch  

SciTech Connect

We report an ultrafast piezoelectric switch for synchrotron x rays. A thin epitaxial film of piezoelectric Pb(Zr,Ti)O{sub 3} works as a diffractive optical switch at frequencies from dc to >1 GHz. The broad frequency range allows single bunches of synchrotron x rays to be selected in an arbitrary sequence. The piezoelectric effect introduces mechanical strains of a fraction of 1% in the Pb(Zr,Ti)O{sub 3} film, which can be used for blocking or passing diffracted x rays.

Grigoriev, Alexei; Do, Dal-Hyun; Kim, Dong Min; Eom, Chang-Beom; Evans, Paul G.; Adams, Bernhard; Dufresne, Eric M. [Department of Materials Science and Engineering, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States); Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2006-07-10

321

Get the LEAD Out!Most lead-containing autoclave tape has stripes running across at an angle ( / / / / / / ); if it has very faint text (the word "autoclaved"), it most likely is a lead-free alternative.  

E-print Network

yd (2160") LF2-048 $6.25 White crepe tape, for use in standard autoclaves, reveals the wordGet the LEAD Out!Most lead-containing autoclave tape has stripes running across at an angle ( / / / / / / ); if it has very faint text (the word "autoclaved"), it most likely is a lead-free alternative. ADDITIONAL

Ford, James

322

Center of Excellence in Piezoelectric Materials and Devices Ben Franklin Technology PArtners  

E-print Network

the exploration of high strain piezoelectric single crystals, new high transition temperature morphotropic phase boundaries, high strain polymer piezoelectrics, Cu metallization for piezoelectric fuel injectors, and thin transducers ­ Wireless ultrasound systems ­ Composites ­ Piezoelectrics for harsh environments (high

dePamphilis, Claude

323

NMR and optical studies of piezoelectric polymers  

SciTech Connect

Progress is reported in several areas dealing with piezoelectric (electroactive) polymers (mostly vinylidene fluoride, trifluoroethylene, copolymers, PVF[sub 2]) and liquid crystals. Optical studies, neutron scattering, NMR, thermal, theory and modeling were done.

Schmidt, V.H.; Tuthill, G.F.

1993-01-01

324

Studying insect motion with piezoelectric sensors  

NASA Astrophysics Data System (ADS)

Piezoelectric materials have been widely used in applications such as transducers, acoustic components, as well as motion, pressure and airborne sensors. Because of the material's biocompatibility and flexibility, we have been able to apply small piezoelectric sensors, made of PVDF, to cockroaches. We built a laboratory test system to study the piezoelectric properties of a bending sensor. The tested motion was compared with that of the sensor attached to a cockroach. Surface characterization and finite element analysis revealed the effects of microstructure on piezoelectric response. The sensor attachment enables us to monitor the insects' locomotion and study their behaviors. The applications of engineering materials to insects opens the door to innovating approaches to integrating biological, mechanical and electrical systems.

Mika, Bartosz; Lee, Hyungoo; González, Jorge M.; Vinson, S. Bradleigh; Liang, Hong

2007-04-01

325

Harvesting Raindrop Energy with Piezoelectrics: a Review  

NASA Astrophysics Data System (ADS)

Harvesting vibration energy from piezoelectric material impacted by raindrops has proved to be a promising approach for future applications. A piezoelectric harvester has interesting advantages such as simple structure, easy fabrication, reduced number of components, and direct conversion of vibrations to electrical charge. Extensive research has been carried out and is still underway to explore this technique for practical applications. This review provides a comprehensive picture of global research and development of raindrop energy harvesting using piezoelectric material to enable researchers to determine the direction of further investigation. The work published so far in this area is reviewed and summarized with relevant suggestions for future work. In addition, a brief experiment was carried out to investigate the suitable piezoelectric structure for raindrop energy harvesting. Results showed that the bridge structure generated a higher voltage compared with the cantilever structure.

Wong, Chin-Hong; Dahari, Zuraini; Abd Manaf, Asrulnizam; Miskam, Muhammad Azman

2015-01-01

326

Piezoelectric MEMS resonator characterization and filter design  

E-print Network

This thesis presents modeling and first measurements of a new piezoelectric MEMS resonator developed at Draper Laboratory. In addition, some simple filter designs incorporating the resonator with predicted performance ...

Kang, Joung-Mo, 1978-

2004-01-01

327

Polarization Stability of Amorphous Piezoelectric Polyimides  

NASA Technical Reports Server (NTRS)

Amorphous polyimides containing polar functional groups have been synthesized and investigated for potential use as high temperature piezoelectric sensors. The thermal stability of the piezoelectric effect of one polyimide was evaluated as a function of various curing and poling conditions under dynamic and static thermal stimuli. First, the polymer samples were thermally cycled under strain by systematically increasing the maximum temperature from 50 C to 200 C while the piezoelectric strain coefficient was being measured. Second, the samples were isothermally aged at an elevated temperature in air, and the isothermal decay of the remanent polarization was measured at room temperature as a function of time. Both conventional and corona poling methods were evaluated. This material exhibited good thermal stability of the piezoelectric properties up to 100 C.

Park, C.; Ounaies, Z.; Su, J.; Smith, J. G., Jr.; Harrison, J. S.

2000-01-01

328

Simulation of Piezoelectric Jellyfish Power Generator  

NASA Astrophysics Data System (ADS)

The energy problem is getting increasingly serious. As such, unused energy recovery technology is crucial for environmental protection, which has been investigated extensively. Several methods have been developed to utilize scavenged energy from the environment, such as waste heat, solar energy, wind energy, and tides energy to convert into useful power. There is a new idea of piezoelectric jellyfish generator which combines the utilization of sea wave and vibration energy. When sea wave passes through the jellyfish, the wave causes the tentacles to vibrate. The tentacles is made of piezoelectric polymer which can convert the strain energy into electrical energy. This paper discusses about the piezoelectric jellyfish's tentacles being disturbed by wave in the sea. We employed the commercial CFD software CFD-ACE+ 2006 to simulate this phenomenon. The parameters including its tentacle length (L) and wave propagating function (Y) are studied which affect the piezoelectric jellyfish capacity to generate power.

Wu, Yeong-Jen; Lai, Wei-Hsiang

329

Piezoelectric polymer actuator and material properties  

Microsoft Academic Search

This paper presents the construction and performance of a PVF2 [poly(vinylidene fluoride), (CH2CF2),] thin film piezoelectric actuator. In addition, the paper discusses the methods used to characterize the viscoelastic properties of the actuator material

V. H. Schmidt; D. Brandt; F. Holloway; A. Vinogradov; D. Rosenberg

1996-01-01

330

Thermally Stable Piezoelectric and Pyroelectric Polymers  

NASA Technical Reports Server (NTRS)

A class of thermally stable piezoelectric and pyroelectric polymers, and an improved method of making them, have been invented. These polymers can be used as substrates for a wide variety of electromechanical transducers, sensors, and actuators.

Simpson, Joycelyn O.; St. Clair, Terry L.

2006-01-01

331

Continuous cross-over from ferroelectric to relaxor state and piezoelectric properties of BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} single crystals  

SciTech Connect

Optimal properties like piezoelectricity can be found in polarizable materials for which the structure changes sharply under small composition variations in the vicinity of their morphotropic phase boundary or the triple point in their isobaric temperature-composition phase diagram. In the latter, lead-free (Ba{sub 0.850}Ca{sub 0.150})(Ti{sub 0.900}Zr{sub 0.100})O{sub 3} ceramics exhibit outstanding piezoelectric coefficients. For the first time, we report the growth of piezoelectric lead-free single crystals in the BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} pseudo-ternary system. The stoichiometry control in the CaO-BaO-TiO{sub 2}-ZrO{sub 2} solid solution led to single crystals with various compositions ranging from (Ba{sub 0.857}Ca{sub 0.143})(Ti{sub 0.928}Zr{sub 0.072})O{sub 3} to (Ba{sub 0.953}Ca{sub 0.047})(Ti{sub 0.427}Zr{sub 0.573})O{sub 3}. We evidenced a continuous cross-over from a ferroelectric state at high titanium content to a relaxor one on increasing the zirconium content. Such a property tuning is rather seldom observed in lead-free ferroelectrics and confirms what was already reported for ceramics. Single crystal with (Ba{sub 0.838}Ca{sub 0.162})(Ti{sub 0.854}Zr{sub 0.146})O{sub 3} composition, which has been grown and oriented along [001] crystallographic direction, displayed electromechanical coefficients d{sub 31} and k{sub 31} of 93 pC.N{sup ?1} and 0.18, respectively, near the room temperature (T?=?305?K)

Benabdallah, F.; Veber, P., E-mail: veber@icmcb-bordeaux.cnrs.fr; Prakasam, M.; Viraphong, O.; Maglione, M. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Université Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Shimamura, K. [National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

2014-04-14

332

Piezoelectric micro-power generation interface circuits  

Microsoft Academic Search

New power conversion circuits to interface to a piezoelectric micro-power generator have been fabricated and tested. Circuit designs and measurement results are presented for a half-wave synchronous rectifier with voltage doubler, a full-wave synchronous rectifier and a passive full-wave rectifier circuit connected to the piezoelectric micro-power generator. The measured power efficiency of the synchronous rectifier and voltage doubler circuit fabricated

Triet T. Le; Jifeng Han; Annette von Jouanne; Kartikeya Mayaram; Terri S. Fiez

2006-01-01

333

Energy harvesting with piezoelectric drum transducer  

Microsoft Academic Search

Piezoelectric materials can convert ambient vibrations into electrical energy. In this letter, the capability of harvesting the electrical energy from mechanical vibrations in a dynamic environment through a piezoelectric drum transducer has been investigated. Under a prestress of 0.15 N and a cyclic stress of 0.7 N, a power of 11 mW was generated at the resonance frequency of the

Sheng Wang; Kwok Ho Lam; Cheng Liang Sun; Kin Wing Kwok; Helen Lai Wa Chan; Ming Sen Guo; Xing-Zhong Zhao

2007-01-01

334

Improved Multiple-DOF SAW Piezoelectric Motors  

NASA Technical Reports Server (NTRS)

Surface-acoustic-wave (SAW) piezoelectric motors of a proposed type would be capable of operating in multiple degrees of freedom (DOFs) simultaneously and would be amenable to integration into diverse structures and mechanisms. These motors would be compact and structurally simple and would not contain bearings or lead screws. One example of a particularly useful motor of this type would be a two-dimensional- translation stage. Another such example would be a self-actuated spherical joint that could be made to undergo controlled, simultaneous rotations about two orthogonal axes: Such a motor could serve as a mechanism for aiming an "eyeball" camera or as a compact transducer in, and an integral part of, a joint in a robot arm. The multiple-DOF SAW piezoelectric motors as now proposed would be successors to the ones reported in "Multiple-DOF Surface-Acoustic-Wave Piezoelectric Motors" (NPO-20735), NASA Tech Briefs, Vol. 24, No. 12 (December 2000), page 5b. The basic principle of operation of a multiple-DOF SAW piezoelectric motor is a straightforward extension of that of single-DOF SAW piezoelectric motors, which have been reported in several previous NASA Tech Briefs articles: For example, in the case of a linear SAW piezoelectric motor, piezoelectric transducers at opposite ends of a stator excite surface acoustic waves that travel along the surface of the stator. An object (denoted the slider) is pressed against the stator with sufficient pressure (in practice .300 MPa) that it remains in frictional contact with the stator at all times. The slider rides the crests of the waves and is thereby made to move along the surface of the stator. The direction of motion (forward or backward) is controlled by selecting the relative phase of waves generated by the two piezoelectric transducers. The speed increases with the amplitude of the waves and thus with the magnitude of the voltage applied to the transducers.

Bar-Cohen, Yoseph; Bao, Xiaoqi; Hull, Anthony; Wright, John

2003-01-01

335

Half-Heusler semiconductors as piezoelectrics.  

PubMed

We use a first-principles rational-design approach to demonstrate the potential of semiconducting half-Heusler compounds as a previously unrecognized class of piezoelectric materials. We perform a high-throughput scan of a large number of compounds, testing for insulating character and calculating structural, dielectric, and piezoelectric properties. Our results provide guidance for the experimental realization and characterization of high-performance materials in this class that may be suitable for practical applications. PMID:22861897

Roy, Anindya; Bennett, Joseph W; Rabe, Karin M; Vanderbilt, David

2012-07-20

336

Piezoelectric actuation systems: optimization of driving electronics  

Microsoft Academic Search

Voltage control is by far the most common strategy for driving piezoelectric actuators, but it is, at times, handicapped by large, inefficient amplifiers and nonlinear piezoelectric actuator behavior. Optimizing voltage-feedback amplifiers for driving capacitive-type loads with amplifier schemes such as pulse-width-modulation promises to drastically reduce amplifier weight and improve efficiency. This development work is currently in progress and is discussed

David V. Newton; John A. Main; Ephrahim Garcia; Lloyd Massengill

1996-01-01

337

Peristaltic micropump system with piezoelectric actuators  

Microsoft Academic Search

This work presents a driving system for a peristaltic micropump that is based on piezoelectric actuation. The effects of the\\u000a actuation sequence on pump performance are also considered. A valveless peristaltic micropump based on piezoelectric actuation\\u000a is designed and fabricated using microelectromechanical system technology. The pump has three parts––silicon, Pyrex glass\\u000a and commercially available bulk PZT (lead zirconate titanate) chips.

Ling-Sheng Jang; Yung-Chiang Yu

2008-01-01

338

Piezoelectric and electrostrictive polymeric actuator materials  

Microsoft Academic Search

Peizoelectric and electrostrictive polymers are widely used in many areas of electromechanical actuation and transduction. This paper summarizes the current status and recent works in this class of polymers. For the piezoelectric polymers, the electromechanical properties of poly(vinylidene fluoride-trifluoroethylene) copolymers (P(VDF-TrFE), which possess the best piezoelectric performance among the known piezopolymers, are presented. In order to improve the strain capability

Qiming Zhang; Zhong-Yang Cheng; Vivek Bharti; Tian-Bing Xu; H. S. Xu; Tian X. Mai; S. J. Gross

2000-01-01

339

In situ health monitoring of piezoelectric sensors  

NASA Technical Reports Server (NTRS)

An in situ health monitoring apparatus may include an exciter circuit that applies a pulse to a piezoelectric transducer and a data processing system that determines the piezoelectric transducer's dynamic response to the first pulse. The dynamic response can be used to evaluate the operating range, health, and as-mounted resonance frequency of the transducer, as well as the strength of a coupling between the transducer and a structure and the health of the structure.

Jensen, Scott L. (Inventor); Drouant, George J. (Inventor)

2013-01-01

340

Highly stretchable piezoelectric-pyroelectric hybrid nanogenerator.  

PubMed

A highly stretchable hybrid nanogenerator has been developed using a micro-patterned piezoelectric polymer P(VDF-TrFE), PDMS-CNT composite, and graphene nanosheets. Mechanical and thermal energies are simultaneously harvested from a single cell of the device. The hybrid nanogenerator exhibits high robustness behavior even after 30% stretching and generates very stable piezoelectric and pyroelectric power outputs due to micro-pattern designing. PMID:24167082

Lee, Ju-Hyuck; Lee, Keun Young; Gupta, Manoj Kumar; Kim, Tae Yun; Lee, Dae-Yeong; Oh, Junho; Ryu, Changkook; Yoo, Won Jong; Kang, Chong-Yun; Yoon, Seok-Jin; Yoo, Ji-Beom; Kim, Sang-Woo

2014-02-01

341

Passive modal damping with piezoelectric shunts  

SciTech Connect

The use of piezoelectric materials in conjunction with passive inductance-resistance-capacitance (RLC) circuits to dampen specific vibration modes is explored. The piezoelectric materials convert mechanical energy to electrical energy, which is then dissipated in the RLC circuit through joule heating. An impulse is applied to a simple cantilevered beam and by varying the inductance and resistance values, the natural oscillation frequency fcir the RLC circuit is tuned to dampen the first mode of vibration.

Granier, J. J. (John J.); Haundhausen, R. J. (R. Jason); Gaytan, G. E. (Gabriel E.)

2001-01-01

342

Suppression method of overshoot on non/less-energy shape-retainment control utilizing hysteretic behavior of piezoelectric actuators  

NASA Astrophysics Data System (ADS)

To keep a shape of a smart structure with piezoelectric actuators bonded on it, electric voltage must be applied continuously. To reduce the amount of electricity usage, a new control method was proposed and its feasibility was examined in the previous studies [Proc. of SPIE 8689 86890C, Proc. of 29th ISTS 2013-c-40]. In this method hysteretic behavior of piezoelectric actuators in strain-electric field relationship was utilized effectively, which behavior is that some amount of strain remains even at zero voltage once a large voltage is applied. The results showed that displacement of a smart beam with a piezoelectric ceramic actuator bonded remained without applying voltage to the actuators after applying a pulsed voltage. However, the displacement overshot a final position while applying the pulsed voltage. That is generally undesirable. In this paper a suppression method of this overshoot was proposed. To this end another piezoelectric actuator was bonded on the beam opposing the original actuator. The original actuator was a soft type while a hard type piezoelectric actuator was used as the opposing actuator. With help from the two types of actuators, the overshoot could be suppressed while applying the pulsed voltage by controlling the voltage for the opposing actuator adequately, and a desired displacement could be obtained at zero voltage after the pulse.

Ikeda, T.; Uchida, T.; Senba, A.; Ishimura, K.

2014-03-01

343

Dielectric loss against piezoelectric power harvesting  

NASA Astrophysics Data System (ADS)

Piezoelectricity is one of the most popular electromechanical transduction mechanisms for constructing kinetic energy harvesting systems. When a standard energy harvesting (SEH) interface circuit, i.e., bridge rectifier plus filter capacitor, is utilized for collecting piezoelectric power, the previous literature showed that the power conversion can be well predicted without much consideration for the effect of dielectric loss. Yet, as the conversion power gets higher by adopting power-boosting interface circuits, such as synchronized switch harvesting on inductor (SSHI), the neglect of dielectric loss might give rise to deviation in harvested power estimation. Given the continuous progress on power-boosting interface circuits, the role of dielectric loss in practical piezoelectric energy harvesting (PEH) systems should receive attention with better evaluation. Based on the integrated equivalent impedance network model, this fast track communication provides a comprehensive study on the susceptibility of harvested power in PEH systems under different conditions. It shows that, dielectric loss always counteracts piezoelectric power harvesting by causing charge leakage across piezoelectric capacitance. In particular, taking corresponding ideal lossless cases as references, the counteractive effect might be aggravated under one of the five conditions: larger dielectric loss tangent, lower vibration frequency, further away from resonance, weaker electromechanical coupling, or using power-boosting interface circuit. These relationships are valuable for the study of PEH systems, as they not only help explain the role of dielectric loss in piezoelectric power harvesting, but also add complementary insights for material, structure, excitation, and circuit considerations towards holistic evaluation and design for practical PEH systems.

Liang, Junrui; Shu-Hung Chung, Henry; Liao, Wei-Hsin

2014-09-01

344

High-bandwidth macro/microactuation for hard-disk drive  

NASA Astrophysics Data System (ADS)

The track density of hard disk drives had been increasing of 30%/year in these last years. The increase in bandwidth is limited by the presence of mechanical resonance modes and other nonlinear in the voice coil motor (VCM) actuators. One approach to overcoming the problem is by using a dual-stage servo mechanism. Dual stage actuator systems composed of a micro actuator and a conventional actuator (VCM)-macro actuator may enable such high track densities to be attained. In this paper, a novel piezoelectric microactuator was successfully designed and mounted on the suspension in hard disk drives. The microactuator is based on the deformation in piezoelectric effect, and drives the head suspension assembly. The paper describes the structure of macro/micro actuators, its principles of operation and mechanical characteristics. The actuators system in hard disk has a high bandwidth, simple structure, and low cost.

Ma, Jianxu; Ang, Marcelo H., Jr.

2000-10-01

345

Piezoelectric microcantilever serum protein detector  

NASA Astrophysics Data System (ADS)

The development of a serum protein detector will provide opportunities for better screening of at-risk cancer patients, tighter surveillance of disease recurrence and better monitoring of treatment. An integrated system that can process clinical samples for a number of different types of biomarkers would be a useful tool in the early detection of cancer. Also, screening biomarkers such as antibodies in serum would provide clinicians with information regarding the patient's response to treatment. Therefore, the goal of this study is to develop a sensor which can be used for rapid, all-electrical, real-time, label-fee, in-situ, specific quantification of cancer markers, e.g., human epidermal receptor 2 (Her2) or antibodies, in serum. To achieve this end, piezoelectric microcantilever sensors (PEMS) were constructed using an 8 mum thick lead magnesium niobate-lead titanate (PMN-PT) freestanding film as the piezoelectric layer. The desired limit of detection is on the order of pg/mL. In order to achieve this goal the higher frequency lateral extension modes were used. Also, as the driving and sensing of the PEMS is electrical, the PEMS must be insulated in a manner that allows it to function in aqueous solutions. The insulation layer must also be compatible with standardized bioconjugation techniques. Finally, detection of both cancer antigens and antibodies in serum was carried out, and the results were compared to a standard commercialized protocol. PEMS have demonstrated the capability of detecting Her2 at a concentration of 5 pg/mL in diluted human serum (1:40) in less than 1 hour. The approach can be easily translated into the clinical setting because the sensitivity is more than sufficient for monitoring prognosis of breast cancer patients. In addition to Her2 detection, antibodies in serum were assayed in order to demonstrate the feasibility of monitoring the immune response for antibody-dependent cellular cytotoxicity (ADCC) in patients on antibody therapies such as Herceptin and Cetuximab. The PEMS displayed a limit of detection of 100 fg/mL, which was 100 times lower than the current methods of protein detection in serum, such as ELISA. Furthermore, the sensitivity of the PEMS device allows it to be capable of determining the dissociation constant, K d, of selective receptors such as antibodies. Using the dose response trials of Her2, Kd has been deduced for H3 scFv, and Herceptin, a commercial antibody specific for Her2.

Capobianco, Joseph A.

346

Model of a Piezoelectric Transducer  

NASA Technical Reports Server (NTRS)

It's difficult to control liquid and gas in propellant tanks in zero gravity. A possible a design would utilize acoustic liquid manipulation (ALM) technology which uses ultrasonic beams conducted through a liquid and solid media, to push gas bubbles in the liquid to desirable locations. We can propel and control the bubble with acoustic radiation pressure by aiming the acoustic waves on the bubble s surface. This allows us to design a so called smart tank in which the ALM devices transfer the gas to the outer wall of the tank and isolating the liquid in the center. Because the heat transfer rate of a gas is lower of that of the liquid it would substantially decrease boil off and provide of for a longer storage life. The ALM beam is composed of little wavelets which are individual waves that constructively interfere with each other to produce a single, combined acoustic wave front. This is accomplished by using a set of synchronized ultrasound transducers arranged in an array. A slight phase offset of these elements allows us to focus and steer the beam. The device that we are using to produce the acoustic beam is called the piezoelectric transducer. This device converts electrical energy to mechanical energy, which appears in the form of acoustic energy. Therefore the behavior of the device is dependent on both the mechanical characteristics, such as its density, cross-sectional area, and its electrical characteristics, such as, electric flux permittivity and coupling factor. These devices can also be set up in a number of modes which are determined by the way the piezoelectric device is arranged, and the shape of the transducer. For this application we are using the longitudinal or thickness mode for our operation. The transducer also vibrates in the lateral mode, and one of the goals of my project is to decrease the amount of energy lost to the lateral mode. To model the behavior of the transducers I will be using Pspice, electric circuit modeling tool, to determine the transducer's electrical characteristics at the frequency of interest. This will also help me determine the characteristics of an impedance matching network to operate the transducer at its optimum efficiency. For this I will use ABMs (analog behavioral modeling) to model dependent current and voltage sources that represent the transducer. I have also been working on the Labview control software for the phased array used to control the bubbles, and will begin testing on that before the end of my internship.

Goodenow, Debra

2004-01-01

347

Speed limitations of optical switching using a piezoelectric transducer  

E-print Network

. The mechanical motion results from a dimensional change in the piezoelectric material in response to an applied voltage. A finite element model is used to predict the response speed of the piezoelectric element. Predictions that sub-micro second switching...

Wang, Chuan-Sheng

2012-06-07

348

Acoustoelectric Harmonic Generation in a Photoconductive Piezoelectric Semiconductor  

E-print Network

Acoustoelectric Harmonic Generation in a Photoconductive Piezoelectric Semiconductor W. Arthur, R harmonics in the low frequency regime (. Piezoelectric semiconductors can exhibit harmonic generation because of interactions between the acoustic

349

Love wave propagation in functionally graded piezoelectric material layer  

E-print Network

Love wave propagation in functionally graded piezoelectric material layer Jianke Du *, Xiaoying Jin is used to investigate Love waves in functionally graded piezoelectric material (FGPM) layer bonded. Numerical examples indicate that appropriate gradient distributing of the material properties make Love

Wang, Ji

350

Structural and dielectric properties of a new lead-free ferroelectric Ba0.8Ca0.2Ti0.8Ge0.2O3 ceramics  

NASA Astrophysics Data System (ADS)

This paper reports the development of a lead free Ba0.8Ca0.2Ti0.8Ge0.2O3 (BCTG) ceramics elaborated by a conventional sintering process. The BCTG exhibits interesting ferroelectric and dielectric properties. The XRD analysis showed that 20 at.% of Ge doping can be fully incorporated into the perovskite lattice of Ba1-xCaxTiO3. Dielectric properties revealed that the BCTG ceramic undergone a second order phase transition type at around 120 °C independently of the used frequency and behaves as displacive ferroelectric. Ferroelectric investigation showed that P-E hysteresis loop could be obtained at low applied electrical field. The BCTG compound may be highly promising for applications as lead-free ferroelectric materials to reduce environmental damages.

Asbani, B.; Lahmar, A.; Amjoud, M.; Dellis, J.-L.; Gagou, Y.; Mezzane, D.; El Marssi, M.

2014-07-01

351

High-Dynamic Bridge Amplifiers with Generator for Piezoelectric Actuator  

Microsoft Academic Search

Piezoelectric amplifier is a very important part of the piezoelectric actuator.Not only positioning accuracy,but also dynamic performance and power are demanded more and more highly. At present piezoelectric amplifier are mainly used in static applications, power and frequency response are usually incompatible.This paper developed a new type of piezoelectric amplifier to meet high demand for dynamic,which takes dual-power supply, bridge-output

Changhai Ru; Zhenhua Wang

2011-01-01

352

Piezoelectric biosensor with a ladder polymer substrate coating  

DOEpatents

A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor.

Renschler, Clifford L. (Tijeras, NM); White, Christine A. (Albuquerque, NM); Carter, Robert M. (New Orleans, LA)

1998-01-01

353

Multilayer piezoelectric linear ultrasonic motor for camera module  

Microsoft Academic Search

Piezoelectric linear ultrasonic motors have been widely studied for auto focusing devices of digital cameras and cellular\\u000a phones due to their simple structure. A piezoelectric motor operated at low voltages, not achievable using bulk piezoelectrics,\\u000a is required for the camera module of cellular phone. In this study, a tiny piezoelectric linear motor was fabricated and its\\u000a dynamic properties at low

Dong-Soo Paik; Kyoung-Ho Yoo; Chong-Yun Kang; Bong-Hee Cho; Sahn Nam; Seok-Jin Yoon

2009-01-01

354

Multilayer Piezoelectric Stack Actuator Characterization  

NASA Technical Reports Server (NTRS)

Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

2008-01-01

355

A multiaxial piezoelectric energy harvester  

NASA Astrophysics Data System (ADS)

An important limitation in the classical energy harvesters based on cantilever beam structure is its monodirectional sensibility. The external excitation must generate an orthogonal acceleration from the beam plane to induced flexural deformation. If the direction of the excitation deviates from this privileged direction, the harvester output power is drastically reduced. This point is obviously very restrictive in the case of an arbitrary excitation direction induced for example by human body movements or vehicles vibrations. In order to overcome this issue of the conventional resonant cantilever configuration with seismic mass, a multidirectional harvester is introduced here by the authors. The multidirectional ability relies on the exploitation of 3 degenerate structural vibration modes where each of them is induced by the corresponding component of the acceleration vector. This specific structure has been already used for 3 axis accelerometers but the approach is here totally revisited because the final functional goal is different. This paper presents the principle and the design considerations of such multidirectional piezoelectric energy harvester. A finite element model has been used for the harvester optimisation. It has been shown that the seismic mass is a relevant parameter for the modes tuning because the resonant frequency of the 1st exploited flexural mode directly depends on the mass whereas the resonance frequency of the 2nd flexural mode depends on its moment of inertia. A simplified centimetric prototype limited to a two orthogonal direction sensibility has permitted to valid the theoretical approach.

Mousselmal, H. D.; Cottinet, P. J.; Quiquerez, L.; Remaki, B.; Petit, L.

2013-04-01

356

Narcotics detection using piezoelectric ringing  

NASA Astrophysics Data System (ADS)

Piezo-electric ringing (PER) has been demonstrated to be an effective means of scanning cargo for the presence of hidden narcotics. The PER signal is characteristic of certain types of crystallized material, such as cocaine hydrochloride. However, the PER signal cannot be used to conclusively identify all types of narcotic material, as the signal is not unique. For the purposes of cargo scanning, the PER technique is therefore most effective when used in combination with quadrupole resonance analysis (QRA). PER shares the same methodology as QRA technology, and can therefore be very easily and inexpensively integrated into existing QRA detectors. PER can be used as a pre-scanning technique before the QRA scan is applied and, because the PER scan is of a very short duration, can effectively offset some of the throughput limitations of standard QRA narcotics detectors. Following is a discussion of a PER detector developed by Quantum Manetics under contract to United States Customs. Design philosophy and performance are discussed, supported by results from recent tests conducted by the U.S. Drug Enforcement Agency and U.S. Customs.

Rayner, Timothy J.; Magnuson, Erik E.; West, Rebecca; Lyndquist, R.

1997-02-01

357

VDER 12P0S 2MM VERT GOLD -87831-1220 http://parts.digikey.eom/l/parts/350398-conn-header-12pos-2inm-ver.. ^ Lead free  

E-print Network

VDER 12P0S 2MM VERT GOLD - 87831-1220 http://parts.digikey.eom/l/parts/350398-conn-header-12pos-2inm-ver.. Keywords:: ° In stock ^ Lead free ^ RoHS Compliant ^: Search/\\gain. Gold Through Hole-1220 CONN HEADER 12P0S 2MM VERT GOLD - 87831-1220 - Connectors, Interconnects Digi-Key Part Number

Kleinfeld, David

358

High-Fidelity Piezoelectric Audio Device  

NASA Technical Reports Server (NTRS)

ModalMax is a very innovative means of harnessing the vibration of a piezoelectric actuator to produce an energy efficient low-profile device with high-bandwidth high-fidelity audio response. The piezoelectric audio device outperforms many commercially available speakers made using speaker cones. The piezoelectric device weighs substantially less (4 g) than the speaker cones which use magnets (10 g). ModalMax devices have extreme fabrication simplicity. The entire audio device is fabricated by lamination. The simplicity of the design lends itself to lower cost. The piezoelectric audio device can be used without its acoustic chambers and thereby resulting in a very low thickness of 0.023 in. (0.58 mm). The piezoelectric audio device can be completely encapsulated, which makes it very attractive for use in wet environments. Encapsulation does not significantly alter the audio response. Its small size (see Figure 1) is applicable to many consumer electronic products, such as pagers, portable radios, headphones, laptop computers, computer monitors, toys, and electronic games. The audio device can also be used in automobile or aircraft sound systems.

Woodward, Stanley E.; Fox, Robert L.; Bryant, Robert G.

2003-01-01

359

Ultrasonic wave propagation in multilayered piezoelectric substrates  

SciTech Connect

Due to the increasing demand for higher operating frequency, lower attenuation, and stronger piezoelectricity, use of the layered structure has become necessary. Theoretical studies are carried out for ultrasonic waves propagating in the multilayered piezoelectric substrates. Each layer processes up to as low as monoclinic symmetry with various thickness and orientation. A plane acoustic wave is assumed to be incident, at varied frequency and incidence angle, from a fluid upon a multilayered substrate. Simple analytical expressions for the reflection and transmission coefficients are derived from which all propagation characteristics are identified. Such expressions contain, as a by-product, the secular equation for the propagation of free harmonic waves on the multilayered piezoelectric substrates. Solutions are obtained for the individual layers which relate the field variables at the upper layer surfaces. The response of the total system proceeds by satisfying appropriate interfacial conditions across the layers. Based on the boundary conditions, two cases, {open_quotes}shorted{close_quotes} and {open_quotes}free{close_quotes}, are derived from which a so-called piezoelectric coupling factor is calculated to show the piezoelectric efficiency. Our results are rather general and show that the phase velocity is a function of frequency, layer thickness, and orientation.

Chien, H.T.; Sheen, S.H.; Raptis, A.C.

1994-04-11

360

Rapid Communications Strong piezoelectricity in individual GaN nanowires  

E-print Network

microscopy (PFM). PFM is a method based on AFM for probing converse piezoelectric effects at the nanoscale piezoelectricity in individual single-crystal GaN nanowires revealed by direct measurement of the piezoelectric, optoelectronic devices, and nanogenerators for self-powered nanodevices.[1,2] Recent dem- onstrations of energy

Espinosa, Horacio D.

361

Piezoelectric coefficients of l-alanine doped TGS crystals  

Microsoft Academic Search

Double beam laser interferometry has been used to study small displacement of LATGS crystals caused by the converse piezoelectric effect. All eight nonzero mutually independent piezoelectric coefficients di? have been derived. The temperature dependence of the piezoelectric coefficient d22 has been measured using the single beam Michelson interferometer. The phase transition temperature was determined near 324K.

Dagmar Barosova; Stanislav Panos

2004-01-01

362

Multilayer Piezoelectric Ceramic Actuator with Interdigital Internal Electrodes  

Microsoft Academic Search

A multilayer piezoelectric ceramic actuator with interdigital internal electrodes has been developed. The internal electrodes of this actuator are line electrodes which are printed on piezoelectric ceramic green sheets and stacked such that alternating electrode lines are displaced by one-half pitch. This actuator is displaced at right angles to the stacking direction due to the piezoelectric longitudinal effect. Therefore, it

Junichi Ohashi; Yoshiaki Fuda; Tomeji Ohno

1993-01-01

363

Finite element analyses of cracks in piezoelectric structures: a survey  

Microsoft Academic Search

Piezoelectric materials have widespread applications in modern technical areas such as mechatronics, smart structures or microsystem technology, where they serve as sensors or actuators. For the assessment of strength and reliability of piezoelectric structures under combined electrical and mechanical loading, the existence of cracklike defects plays an important role. Meanwhile, piezoelectric fracture mechanics has been established quite well, but its

M. Kuna

2006-01-01

364

Nonlinear Control Design for a Piezoelectric-Driven Nanopositioning Stage  

E-print Network

in the piezoelectric actuator. The nonlinear control design is compared to Proportional-Integral-Derivative (PID the nonlinear, hysteretic and relaxation behavior of the piezoelectric actuator. The constitutive model is implemented in a structural model of a nanopositioning stage that uses piezoelectric stack actuators. Both

365

HYBRID DC ACCURATE CHARGE AMPLIFIER FOR LINEAR PIEZOELECTRIC POSITIONING  

E-print Network

HYBRID DC ACCURATE CHARGE AMPLIFIER FOR LINEAR PIEZOELECTRIC POSITIONING Andrew J. Fleming, S. O-frequency and DC operation of the amplifier. Keywords: Charge, Amplifier, Driver, Source, DC, Piezoelectric, Load 1., 2000) (Jaffe et al., 1971). When used in an actuating role, piezoelectric trans- ducers display

Fleming, Andrew J.

366

Chandrasekaran and Lindner 1 Power Flow Through Controlled Piezoelectric Actuators  

E-print Network

augmentation loop. When the piezoelectric actuator is driven by a current amplifier, we show that accelerationRevised Chandrasekaran and Lindner 1 Power Flow Through Controlled Piezoelectric Actuators Sriram of Intelligent Material Systems and Structures JIMSS-00-033 October, 2000 Keywords : piezoelectric actuators

Lindner, Douglas K.

367

Technical Communication Piezoelectric Vibrating Needle and Catheter for  

E-print Network

) were customized by adhering in place two piezoelectric actuators. These created 1­8 kHz vibrations when by removing the proximal insulation and soldering in place a piezoelectric actuator (Fig. 1). Similarly, a 20 of the catheter and another piezoelectric actua- tor was epoxied to the exposed metal (Fig. 2). The actuators

Smith, Stephen

368

DRIVING MODES AND THEIR MR-COMPATIBILITY OF PIEZOELECTRIC ACTUATOR  

Microsoft Academic Search

http:\\/\\/unit.aist.go.jp\\/humanbiomed\\/surgical\\/ Abstract: In this research, piezoelectric actua- tor's noise to MRI (Magnetic Resonance Imag- ing) was tested by signal-to-noise ratio (SNR) of phantom images to validate the MR-compatibility of piezoelectric actuator. Piezoelectric actuators of various strokes (4\\

Yoshihiko KOSEKI; T. TSUMUKI; K. MIZUHARA; K. CHINZEI

369

Nonlinear Optimal Tracking Control of a Piezoelectric Nanopositioning Stage  

E-print Network

, piezoelectric materials are chosen as actuators in nanopositioning stages as well as embedded actuators within and hysteresis in the piezoelectric actuator and subsequently in the positioning stage. In addition, low scan in piezoelectric actuators used in nanopositioning stages [3, 12, 13, 14, 19

370

Piezoelectric pick-up device for internal combustion engine  

Microsoft Academic Search

A piezoelectric pick-up device is described for an internal combustion engine comprising: a metal housing having a threaded bottom projection; threaded metal mounting rod means projecting from the inner bottom surface of the metal housing into the interior thereof; a piezoelectric element disposed in the housing interior and fitted on the mounting rod means. The piezoelectric element is electrically coupled

H. Miyata; S. Kawajiri

1987-01-01

371

Cooperativity in the enhanced piezoelectric response of polymer nanowires.  

PubMed

Multilayered, aligned arrays of organic nanowires show unique advantages in their piezoelectric response. Here, the cooperative, electromechanical mechanism at the base of the enhanced response of aligned arrays of piezoelectric nanostructures in mutual contact is unveiled. An enhancement of the piezoelectric voltage by two orders of magnitude compared with individual nanofibers is demonstrated in the arrays. PMID:25355372

Persano, Luana; Dagdeviren, Canan; Maruccio, Claudio; De Lorenzis, Laura; Pisignano, Dario

2014-12-01

372

Design, fabrication and testing of piezoelectric polymer PVDF microactuators  

Microsoft Academic Search

Piezoelectric polymers are increasingly considered as favorable materials for microactuator applications due to their fast response, low operating voltages and greater efficiencies of operation. However, the difficulty of forming structures and shapes has so far limited the range of mechanical design. In this work, the design and fabrication of a unimorph piezoelectric cantilever actuator using piezoelectric polymer polyvinylidene fluoride (PVDF)

Yao Fu; Erol C Harvey; Muralidhar K Ghantasala; Geoff M Spinks

2006-01-01

373

Modelling of piezoelectric behaviour for actuator and sensor applications  

Microsoft Academic Search

A significant amount of research has shown that piezoelectric sensors and actuators can be used successfully to damp vibrations in large flexible space structures. In this report, the equations used to characterize the behavior of piezoelectric materials are developed. The equations are then used to develop electro mechanical models of piezoelectric actuator and sensor operations. The physics associated with the

Anthony Faria Vaz

1991-01-01

374

Simultaneous liquid viscosity and density determination with piezoelectric unimorph cantilevers  

E-print Network

Simultaneous liquid viscosity and density determination with piezoelectric unimorph cantilevers Wan a piezoelectric unimorph cantilever as a liquid viscosity-and-density sensor. The fabricated piezoelectric mass and the damping coefficient of the liquid, we show that for a given liquid density and viscosity

Aksay, Ilhan A.

375

Ferroelectric materials for piezoelectric actuators by optimal design  

Microsoft Academic Search

Optimization methods provide a systematic means of designing heterogeneous materials with tailored properties and microstructures focussing on a specific objective. An optimization procedure incorporating a continuum modeling is used in this work to identify the ideal orientation distribution of ferroelectrics (FEs) for application in piezoelectric actuators. Piezoelectric actuation is dictated primarily by the piezoelectric strain coefficients di?. Crystallographic orientation is

K. P. Jayachandran; J. M. Guedes; H. C. Rodrigues

2011-01-01

376

Engineering of piezoelectric properties in ferroelectric ceramics and thin films  

Microsoft Academic Search

The paper discusses different possibilities for controlling piezoelectric properties of ferroelectric materials and devices. The piezoelectric properties engineering can be made on different scales. Tuning of the piezoelectric response by controlling con- tributions from domain walls displacement is used to illustrate engineering on nanometer scale. Texture control in ferroelec- tric films and grain size control is discussed as an example

D. DAMJANOVIC; F. CHU; D. V. TAYLOR; M. DEMARTIN MAEDER; L. SAGALOWICZ; P. DURAN MARTIN; N. SETTER

377

Low-power piezoelectric micro-machined valve  

NASA Technical Reports Server (NTRS)

A piezoelectric microvalve employs a valve element formed of hermetically sealed and opposed plates flexed together by a cross axis piezoelectric element. Large flow modulation with small piezoelectric actuator displacement is obtained by perimeter augmentation of the valve seat which dramatically increases the change in valve flow area for small deflections.

Gianchandani, Yogesh B. (Inventor); Nellis, Gregory Francis (Inventor); Klein, Sanford A. (Inventor); Park, John Moon (Inventor); Evans, Allan Thomas (Inventor); Taylor, Ryan (Inventor); Brosten, Tyler R. (Inventor)

2010-01-01

378

Pulsed DC magnetron sputtered piezoelectric thin film aluminum nitride - Technology and piezoelectric properties  

NASA Astrophysics Data System (ADS)

Pulsed DC magnetron sputtered aluminum nitride (AlN) thin films are prepared on several seed layers and at different sputtering conditions. The piezoelectric c-axis (002) orientation of the AlN is analyzed with X-ray diffraction method. The transverse piezoelectric coefficient d31 is determined with a Laser-Doppler-Vibrometer at cantilevers and membranes by analytical calculations and finite element method. Additionally, thin film AlN on bulk silicon is used to characterize the longitudinal piezoelectric charge coefficient d33.

Stoeckel, C.; Kaufmann, C.; Hahn, R.; Schulze, R.; Billep, D.; Gessner, T.

2014-07-01

379

Magnetocaloric piezoelectric composites for energy harvesting  

NASA Astrophysics Data System (ADS)

Magnetocaloric alloy, Gd5Si2Ge2, was developed into a composite with the poly(vinylidene fluoride) (PVDF) piezoelectric polymer. This multifunctional material possesses unique properties that are suitable for energy conversion and harvesting. Experimental approaches include using an arc melting technique to synthesize the Gd5Si2Ge2 (GSG) alloy and the spinning casting method to fabricate the composite. The materials were characterized using various techniques at different length scales. These include atomic force microscopy (AFM), optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The results indicated that the phase transformation of the magnetocaloric material close to its Curie temperature induced a significant increase in power generation in the piezoelectric polymer. The power output of a laminated structure was 1.1 mW, more than 200 thousand times higher than the piezoelectric materials alone (5.1 nW).

Cleveland, Michael; Liang, Hong

2012-04-01

380

Design, fabrication, and properties of 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution  

NASA Astrophysics Data System (ADS)

The laminated 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramic as active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction of piezoelectric phase have large piezoelectric strain constant and relative permittivity, and the piezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction of piezoelectric phase have large piezoelectric voltage constant, but also large dielectric loss. The composite with gradually increased dimension of piezoelectric ceramic layer has the smallest dielectric loss, and that with the gradually increased dimension of matrix layer has the largest piezoelectric voltage constant. The novel piezoelectric composites show potential applications in fabricating ultrasonic transducers with varied surface vibration amplitude of the transducer.

Dongyu, Xu; Xin, Cheng; Banerjee, Sourav; Shifeng, Huang

2014-12-01

381

Radial-Electric-Field Piezoelectric Diaphragm Pumps  

NASA Technical Reports Server (NTRS)

In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.

Bryant, Robert G.; Working, Dennis C.; Mossi, Karla; Castro, Nicholas D.; Mane, Pooma

2009-01-01

382

A self diagnostic system for piezoelectric sensors  

NASA Technical Reports Server (NTRS)

A technique for determining the mounting conditions of a piezoelectric accelerometer is presented. This technique electrically stimulates the piezoelectric element in the 'diagnostic' frequency band measuring the electrical frequency response characteristics across a capacitive load impedance. The diagnostic frequency band is tipically much higher than the operating bandwidth of the accelerometer. The resonant frequencies of the accelerometer are included in the diagnostic band. By monitoring the shift in these resonant frequencies, via electrical stimulation techniques, certain diagnostic conditions including mounting conditions can be determined. Experimental data from a compression mode accelerometer is used to demonstrate this technique.

Atherton, William J.; Flanagan, Patrick M.

1989-01-01

383

Surface-Acoustic-Wave Piezoelectric Microbalance  

NASA Technical Reports Server (NTRS)

Improved piezoelectric microbalances developed for use in measuring masses of volcanic, aerosol, and other small particles suspended in air. Sensitive microbalance used to analyze airborne particles in real time in environments as diverse as clean rooms or upper atmosphere. Surface-acoustic-wave resonator includes input and output sets of interdigitated electrodes and two passive conductive patterns acting as reflectors. Mechanical energy travels both ways out from middle and reflected back toward middle. Microbalance and associated circuitry fit in small package. Circuit draws only 80 mA at 5 V. Sensitivity more than 400 times that of bulk piezoelectric microbalance.

Chuan, Raymond L.; Bowers, William D.

1992-01-01

384

Broadband pulsed flow using piezoelectric microjets  

NASA Astrophysics Data System (ADS)

A piezohydraulic microjet design and experimental results are presented to demonstrate broadband active flow control for applications on various aircraft structures including impinging jets, rotor blades, cavity bays, etc. The microjet actuator includes a piezoelectric stack actuator and hydraulic circuit that is used to throttle a 400 ?m diameter microjet using hydraulic amplification of the piezoelectric stack actuator. This system is shown to provide broadband pulsed flow actuation up to 800 Hz. Unsteady pressure measurements of the microjet's exit flow are coupled with high-speed phase imagery using micro-Schlieren techniques to quantify the flow field. These results are compared with in situ stack actuator displacements using strain gauge measurements.

Hogue, Joshua; Solomon, John; Hays, Michael; Alvi, Farrukh; Oates, William

2010-04-01

385

Telescoping cylindrical piezoelectric fiber composite actuator assemblies  

NASA Technical Reports Server (NTRS)

A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

2010-01-01

386

Lead-free and lead-based ABO3 perovskite relaxors with mixed-valence A-site and B-site disorder: Comparative neutron scattering structural study of (Na1/2Bi1/2)TiO3 and Pb(Mg1/3Nb2/3)O3  

NASA Astrophysics Data System (ADS)

We report the results of neutron elastic-scattering measurements made between -250 °C and 620 °C on the lead-free relaxor (Na1/2Bi1/2)TiO3 (NBT). Strong, anisotropic, elastic diffuse scattering intensity decorates the (100), (110), (111), (200), (210), and (220) Bragg peaks at room temperature. The wave-vector dependence of this diffuse scattering is compared to that in the lead-based relaxor Pb(Mg1/3Nb2/3)O3 (PMN) to determine if any features might be common to relaxors. Prominent ridges in the elastic diffuse scattering intensity contours that extend along ?110? are seen that exhibit the same zone dependence as those observed in PMN and other lead-based relaxors. These ridges disappear gradually on heating above the cubic-to-tetragonal phase transition temperature TCT = 523 °C, which is also near the temperature at which the dielectric permittivity begins to deviate from Curie-Weiss behavior. We thus identify the ?110?-oriented ridges as a relaxor-specific property. The diffuse scattering contours also display narrower ridges oriented along ?100? that are consistent with the x-ray results of Kreisel [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.68.014113 68, 014113 (2003)]; these vanish near 320 °C, indicating that they have a different physical origin. The ?100?-oriented ridges are not observed in PMN. We observe no equivalent relaxor-specific elastic diffuse scattering from the homovalent relaxor analogues K0.95Li0.05TiO3 (A-site disordered) and KTa0.95Nb0.05O3 (B-site disordered). This suggests that the ?110?-oriented diffuse scattering ridges are correlated with the presence of strong random electric fields and invites a reassessment of what defines the relaxor phase. We find that doping NBT with 5.6% BaTiO3, a composition close to the morphotropic phase boundary with enhanced piezoelectric properties, increases the room-temperature correlation length along [11¯0] from 40 to 60 Å while doubling the associated integrated diffuse scattering. Similar behavior was reported by Matsuura [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.74.144107 74, 144107 (2006)] for morphotropic compositions of PMN doped with PbTiO3. Finally, we comment on the recent observation of monoclinicity in NBT at room temperature by placing a strict bound on the strength of the (½½½) superlattice reflection associated with the Cc space group based on the atomic coordinates published in the x-ray study by Aksel [Appl. Phys. Lett.APPLAB0003-695110.1063/1.3573826 98, 152901 (2011)] for NBT. We show that a skin effect, analogous to that reported in the relaxors PZN-xPT and PMN-xPT, can reconcile our neutron single-crystal data with the x-ray powder data of Aksel [Appl. Phys. Lett.APPLAB0003-695110.1063/1.3573826 98, 152901 (2011)]. Our finding of a skin effect in a lead-free, A-site disordered, heterovalent relaxor supports the idea that it arises in the presence of strong random electric fields.

Ge, Wenwei; Devreugd, Christopher P.; Phelan, D.; Zhang, Qinhui; Ahart, Muhtar; Li, Jiefang; Luo, Haosu; Boatner, Lynn A.; Viehland, Dwight; Gehring, Peter M.

2013-11-01

387

Lead-free and lead-based ABO3 perovskite relaxors with mixed-valence A-site and B-site disorder: A comparative neutron scattering structural study of (Na1/2Bi1/2)TiO3 and Pb(Mg1/3Nb2/3)O3  

SciTech Connect

We report the results of neutron elastic scattering measurements between -250oC and 620oC on the lead-free relaxor Na1/2Bi1/2TiO3 (NBT). Strong, anisotropic, elastic diffuse scattering intensity decorates the (100), (110), (111), (200), (220), and (210) Bragg peaks at room temperature. The wavevector dependence of this diffuse scattering is compared to that in the lead-based relaxor PbMg1/3Nb2/3O3 (PMN) to determine if any features might be common to relaxors. Prominent ridges in the elastic diffuse scattering intensity contours that extend along <110> are seen that exhibit the same zone dependence as those observed in PMN and other lead-based relaxors. These ridges disappear gradually on heating above the cubic-to-tetragonal phase transition temperature TCT = 523oC, which is also near the temperature at which the dielectric permittivity begins to deviate from Curie-Weiss behavior. We thus identify the <110>-oriented ridges as a relaxor-specific property. The diffuse scattering contours also display narrower ridges oriented along <100> that are consistent with the x-ray results of Kreisel et al. (2003); these vanish below 320oC indicating that they have a different physical origin. The <100>-oriented ridges are not observed in PMN. We observe no equivalent relaxor-specific elastic diffuse scattering from the homovalent relaxor analogues K0.95Li0.05TiO3 (A-site disordered) and KTa0.95Nb0.05O3 (B-site disordered). This suggests that the <110>-oriented diffuse scattering ridges are correlated with the presence of strong random electric fields and invites a reassessment of what defines the relaxor phase. We find that doping NBT with 5.6% BaTiO3, a composition close to the morphotropic phase boundary with enhanced piezoelectric properties, increases the room temperature correlation length along [1 1 0] from 40 to 60 while doubling the associated integrated diffuse scattering. Similar behavior was reported by Matsuura et al. (2006) for compositions of PMN doped with PbTiO3. Finally, we comment on the recent observation of monoclinicity in NBT at room temperature by placing a strict bound on the strength of the ( ) superlattice reflection associated with the Cc space group based on the atomic coordinates published in the x-ray study by Aksel et al. (2011) for NBT. We argue that a skin effect, analogous to that reported in the relaxors PZN and PMN-10%PT, can reconcile our single-crystal data with the powder data of Aksel et al. We believe this represents the first evidence of the relaxor skin effect in a lead-free relaxor.

Ge, Wenwei [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Devreugd, Christopher [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Phelan, Daniel [National Institute of Standards and Technology (NIST), Gaithersburg, MD] [National Institute of Standards and Technology (NIST), Gaithersburg, MD; Zhang, Qinjui [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS)] [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS); Muhtar, Aheart [Carnegie Institution of Washington] [Carnegie Institution of Washington; Li, Jiefang [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Luo, Haosu [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS)] [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS); Boatner, Lynn A [ORNL] [ORNL; Viehland, Dwight [Virginia Polytechnic Institute and State University] [Virginia Polytechnic Institute and State University; Gehring, P. M. [National Institute of Standards and Technology (NIST)] [National Institute of Standards and Technology (NIST)

2013-01-01

388

Flow energy piezoelectric bimorph nozzle harvester  

NASA Astrophysics Data System (ADS)

There is a need for a long-life power generation scheme that could be used downhole in an oil well to produce 1 Watt average power. There are a variety of existing or proposed energy harvesting schemes that could be used in this environment but each of these has its own limitations. The vibrating piezoelectric structure is in principle capable of operating for very long lifetimes (decades) thereby possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. In order to determine the feasibility of using piezoelectrics to produce suitable flow energy harvesting, we surveyed experimentally a variety of nozzle configurations that could be used to excite a vibrating piezoelectric structure in such a way as to enable conversion of flow energy into useful amounts of electrical power. These included reed structures, spring mass-structures, drag and lift bluff bodies and a variety of nozzles with varying flow profiles. Although not an exhaustive survey we identified a spline nozzle/piezoelectric bimorph system that experimentally produced up to 3.4 mW per bimorph. This paper will discuss these results and present our initial analyses of the device using dimensional analysis and constitutive electromechanical modeling. The analysis suggests that an order-of-magnitude improvement in power generation from the current design is possible.

Sherrit, Stewart; Lee, Hyeong Jae; Walkemeyer, Phillip; Hasenoehrl, Jennifer; Hall, Jeffrey L.; Colonius, Tim; Tosi, Luis Phillipe; Arrazola, Alvaro; Kim, Namhyo; Sun, Kai; Corbett, Gary

2014-04-01

389

Templated Grain Growth of Textured Piezoelectric Ceramics  

Microsoft Academic Search

Crystallographic texturing of polycrystalline ferroelectric ceramics offers a means of achieving significant enhancements in the piezoelectric response. Templated grain growth (TGG) en- ables the fabrication of textured ceramics with single crystal-like properties, as well as single crystals. In TGG, nucleation and growth of the desired crystal on aligned single crystal template particles results in an increased fraction of oriented material

G. L. Messing; S. Trolier-McKinstry; E. M. Sabolsky; C. Duran; S. Kwon; B. Brahmaroutu; H. Yilmaz; P. W. Rehrig; K. B. Eitel; E. Suvaci; M. Seabaugh; K. S. Oh

2004-01-01

390

Miniature piezoelectric triaxial accelerometer measures cranial accelerations  

NASA Technical Reports Server (NTRS)

Tiny triaxial accelerometer whose sensing elements are piezoelectric ceramic beams measures human cranial accelerations when a subject is exposed to a centrifuge or other simulators of g environments. This device could be considered for application in dental, medical, and automotive safety research.

Deboo, G. J.; Rogallo, V. L.

1966-01-01

391

Piezoelectric nanoribbons for monitoring cellular deformations  

E-print Network

Piezoelectric nanoribbons for monitoring cellular deformations Thanh D. Nguyen1 , Nikhil Deshmukh2 cellular forces agree with a theoretical model in 15 which depolarization caused by an applied voltage a silicone elastomer and measure mechanical defor- 20 mations on a cow lung that mimic respiration

Purohit, Prashant

392

Miniature piezoelectric hollow sphere transducers (BBs)  

Microsoft Academic Search

Miniature piezoelectric transducers were prepared from millimeter size hollow spheres which were formed from PZT-5A powder slurries using a coaxial nozzle process. After sintering, the spheres were poled in two ways: radially and tangentially. Principal modes of vibration were found to be a breathing mode near 700 kHz and a thickness mode near 13 MHz for the radially poled spheres,

Sedat Alkoy; Aydin Dogan; Anne-Christine Hladky; P. Langlet; J. E. Cochran; N. E. Newnham

1997-01-01

393

Amplified Piezoelectric Actuators: Static & Dynamic Applications  

Microsoft Academic Search

Amplified Piezoelectric Actuators offer the advantage of large deformation (up to 8%) and large strokes. Because of a prestress applied to the piezo ceramics and an efficient mechanical amplifier, they can produce large strokes both in static and dynamic conditions including resonance. For these reasons, these actuators can be used for micro positioning, structure shaping, structure active damping, vibration generation,

Frank Claeyssen; R. Le Letty; F. Barillot; O. Sosnicki

2007-01-01

394

The theory of a piezoelectric disc gyroscope  

Microsoft Academic Search

The theory of a new type of vibratory rate gyroscope is considered. The design considered is based upon a disk of piezoelectric material on which are deposited drive and pick-off electrodes. The equations of motion of the disk are derived and the response of the gyroscope to constant and harmonic rates of turn determined.

J. S. Burdess; T. Wren

1986-01-01

395

Optimization of switching amplifiers for piezoelectric actuators  

Microsoft Academic Search

The formulation of an optimization problem for the design of a current controlled switching power amplifier to drive a piezoelectric actuator is the subject of this paper. The design is formulated as a continuous optimization problem. A detailed model that includes the anhysteretic nonlinearity between the electric field and polarization is developed and is coupled with a dynamic model of

Sriram Chandrasekaran; Douglas K. Lindner; Ralph C. Smith

2000-01-01

396

A power drive control for piezoelectric actuators  

Microsoft Academic Search

Today piezoelectric actuators are used in a growing number of applications. This article presents a new switching amplifier circuit for multilayer actuators, which allows a fast and precise driving as well as the recovery of energy from the actuator. Having modeled the power electronic analog circuit, its behavior could be well reproduced by a simulation. The design of a digital

G. Gnad; R. Kasper

2004-01-01

397

An Improved Wideband Amplifier for Piezoelectric Actuator  

Microsoft Academic Search

Piezoelectric actuators are becoming increasingly important in such fields as vibration control, precision positioning, acoustics and sonar, and it is mainly driven by voltage in practical application. The amplifier driven by voltage has good stability and static characteristic, but in high speed motion conditions, we have to sacrifice frequency response bandwidth to ensure stability, so its closed loop frequency response

Changhai Ru; Chun Huang; Xiufen Ye; Shuxiang Guo

2007-01-01

398

Piezoelectric Polymer Actuators in Microgravity Applications  

Microsoft Academic Search

We present the continuing development of a full 3-d (six degrees of freedom) active vibration isolation system. Designed for space applications, the project incorporates piezoelectric actuators made of PVDF polymer to dampen systems in microgravity. Position sensitive devices continually update and feed back the relative position of the system to a PC, thereby providing the necessary information to determine the

Paul Cook; V. Hugo Schmidt

2003-01-01

399

Direct measurement of piezoelectric shear coefficient  

NASA Astrophysics Data System (ADS)

Piezoelectric materials exhibit electromechanical coupling which has led to their widespread application for sensors, actuators, and energy harvesters. These materials possess anisotropic behavior with the shear coefficient, and have the largest electromechanical coupling coefficient. However, the shear mode is difficult to measure with existing techniques and thus has not been fully capitalized upon in recent devices. Better understanding of the full shear response with respect to the driving electric field would significantly help the design of optimized piezoelectric shear devices. Here, a simple and low cost direct measurement method based on digital image correlation is developed to characterize the shear response of piezoelectric materials and its nonlinear behavior as a function of external field. The piezoelectric shear coefficient (d15) of a commercial shear plate actuator is investigated in both bipolar and unipolar electric fields. Two different nonlinearities and hysteresis behaviors of the actuators were observed, and the relation between the driving field amplitude and the corresponding d15 coefficient is determined. Moreover, the measured transverse displacement of the plate actuator in simple shear condition is validated through a laser interferometry technique.

Malakooti, Mohammad H.; Sodano, Henry A.

2013-06-01

400

Piezoelectric forceps actuator: theory and experiments.  

PubMed

This paper studies the characteristic performances of a novel piezoelectric forceps actuator (PFA) that has several potential applications for minimally invasive surgery and assembly lines of semiconductor industries. The first part of the paper treats the PFA model, which is comprised of a piezoelectric slightly curved composite beam derived using Hamilton's principle. In the latter part of the paper, the distributed transfer function method is applied to evaluate the transfer function formulation of the cantilevered PFA associated with its boundary conditions. This method will be used to resolve the radial displacements and natural frequencies of the PFA in an exact and closed-form solution, which is validated by in situ fiber optic curvature sensing measurements. The theoretical model predicted the natural frequencies of the first- and second-mode responses of the experimental quite accurately. For a cyclical low-field input, the field-induced displacement appears approximately linear, which seems comparable to the theoretical prediction and reflects primarily the converse piezoelectric effect. A cyclical high-field butterfly-shaped displacement behavior is also analogous to the behavior predicted by the model in that it demonstrates the range of validity of the linear converse piezoelectric effect without consideration of the ferroelectric domain switch effect. PMID:19045912

Susanto, Ken

2008-11-01

401

Piezoelectricity and Electrostriction in Ferroelectric Actuators  

Microsoft Academic Search

Large amplitude driving of ferroelectric actuators has been investigated. Displacement xi, electric charge Q and current I were measured with varying alternating voltage VAC at various frequencies f (120, 500 and 1000 Hz) under voltage bias Vbias (0 to 75 V). Effective piezoelectric and dielectric constants were evaluated from initial slopes of xi and Q vs VAC, respectively. It is

Atsushi Kurihara; Koji Nomura; Ken-ichi Hirota; Takuro Ikeda

1992-01-01

402

Shape control using embedded piezoelectric actuators  

Microsoft Academic Search

This paper describes a Carbon Fibre Re-enforced Polymer (CFRP) panel with a number of piezoelectric bimorph actuators embedded in the neutral plane of the CFRP panel. The shape of the composite panel was controlled by applying a voltage across one or more of the embedded bimorph actuators. The displacement of the composite panel was monitored as a function of position

J. B. Wallace; B. E. Pettit; S. E. Prasad; E. Stenne; S. Kalaycioglu; M. Giray

1996-01-01

403

Instrument For Simulation Of Piezoelectric Transducers  

NASA Technical Reports Server (NTRS)

Electronic instrument designed to simulate dynamic output of integrated-circuit piezoelectric acceleration or pressure transducer. Operates in conjunction with external signal-conditioning circuit, generating square-wave signal of known amplitude for use in calibrating signal-conditioning circuit. Instrument also useful as special-purpose square-wave generator in other applications.

Mcnichol, Randal S.

1996-01-01

404

Using Piezoelectric Materials for Wearable Electronic Textiles  

E-print Network

Using Piezoelectric Materials for Wearable Electronic Textiles Joshua Edmison, Mark Jones, Zahi · Summary Oct. 8, 2002 Tom Martin, ISWC 3 Introduction · Electronic textiles ­ Fabrics with components, 2002 Tom Martin, ISWC 6 Related work: E-textiles · Virginia Tech/ISI-East: STRETCH project ­ Electronic

405

POWER HARVESTING PIEZOELECTRIC SHUNT DAMPING 1  

E-print Network

POWER HARVESTING PIEZOELECTRIC SHUNT DAMPING 1 A. J. Fleming ¤ S. O. R. Moheimani ¤ ¤ School of harvesting the real power normally dissipated by resistive network elements. Keywords: Dampers, Passive, the passive network combined with the inherent capacitance of the PZT creates a damped electrical resonance

Fleming, Andrew J.

406

Piezoelectric Diffraction-Based Optical Switches  

NASA Technical Reports Server (NTRS)

Piezoelectric diffraction-based optoelectronic devices have been invented to satisfy requirements for switching signals quickly among alternative optical paths in optical communication networks. These devices are capable of operating with switching times as short as microseconds or even nanoseconds in some cases.

Spremo, Stevan; Fuhr, Peter; Schipper, John

2003-01-01

407

How Hard is Chocolate?  

NSDL National Science Digital Library

Hardness is probably a concept you are well familiar with. You already know that certain materials are harder than others; in fact, you prove it everyday when you chew your food and your teeth don’t break (because your teeth are harder than the foods you chew). Hardness can be defined as a material's ability to resist a change in shape. Modern hardness testers take a well-defined shape and press it into a material with a certain force, observing the indent it leaves in the material when it is removed. In this lesson, you will be performing hardness testing on different bars of chocolate.

2007-12-20

408

Room temperature electro-caloric effect in lead-free Ba(Zr0.1Ti0.9)1-xSnxO3 (x=0, x=0.075) ceramics  

NASA Astrophysics Data System (ADS)

Electrocaloric effect of lead-free Ba(Zr0.1Ti0.9)1-xSnxO3 (x=0 and x=0.075) ceramics is investigated. In the composition x=0, the electrocaloric strength (?) was about 0.23 K mm/kV at Curie temperature. The incorporation of a small amount of tin (Sn) ions in the matrix of Ba(Zr0.1Ti0.9)O3 was found to decrease the Curie temperature TC toward room temperature while the value of the electrocaloric strength remained practically unchanged (?=0.22 K mm/kV).

Kaddoussi, H.; Gagou, Y.; Lahmar, A.; Belhadi, J.; Allouche, B.; Dellis, J.-L.; Courty, M.; Khemakhem, H.; El Marssi, M.

2015-01-01

409

Piezoelectric energy harvesting: State-of-the-art and challenges  

NASA Astrophysics Data System (ADS)

Piezoelectric energy harvesting has attracted wide attention from researchers especially in the last decade due to its advantages such as high power density, architectural simplicity, and scalability. As a result, the number of studies on piezoelectric energy harvesting published in the last 5 years is more than twice the sum of publications on its electromagnetic and electrostatic counterparts. This paper presents a comprehensive review on the history and current state-of-the art of piezoelectric energy harvesting. A brief theory section presents the basic principles of piezoelectric energy conversion and introduces the most commonly used mechanical architectures. The theory section is followed by a literature survey on piezoelectric energy harvesters, which are classified into three groups: (i) macro- and mesoscale, (ii) MEMS scale, and (iii) nanoscale. The size of a piezoelectric energy harvester affects a variety of parameters such as its weight, fabrication method, achievable power output level, and potential application areas. Consequently, size-based classification provides a reliable and effective basis to study various piezoelectric energy harvesters. The literature survey on each scale group is concluded with a summary, potential application areas, and future directions. In a separate section, the most prominent challenges in piezoelectric energy harvesting and the studies focusing on these challenges are discussed. The conclusion part summarizes the current standing of piezoelectric energy harvesters as possible candidates for various applications and discusses the issues that need to be addressed for realization of practical piezoelectric energy harvesting devices.

Toprak, Alperen; Tigli, Onur

2014-09-01

410

Mn dopant on the "domain stabilization" effect of aged BaTiO3 and PbTiO3-based piezoelectrics  

NASA Astrophysics Data System (ADS)

We report that an obvious difference in the "domain stabilization" effect between 1.0 mol. % Mn doped (Ba1-xSrx)TiO3 and (Pb1-xSrx)TiO3 piezoelectrics with a similar c/a ratio and aging treatment, though typically "increased" stabilization effect occurs with the increase of c/a in each system. The three-time larger microscopic defect dipole field Ei in lead-system from P-E measurements suggests the more aligned defect dipoles through kinetically easier hopping of oxygen vacancy originated from local structure rather than the average structure like c/a may be a primary cause of the strong domain stabilization effect. This may help on the hardening functionality improvement of lead-free systems.

Zhang, Lixue; Liu, Wenfeng; Chen, Wei; Ren, Xiaobing; Sun, Jun; Gurdal, Erkan A.; Ural, Seyit O.; Uchino, Kenji

2012-12-01

411

Session: Hard Rock Penetration  

SciTech Connect

This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hard Rock Penetration - Summary'' by George P. Tennyson, Jr.; ''Overview - Hard Rock Penetration'' by James C. Dunn; ''An Overview of Acoustic Telemetry'' by Douglas S. Drumheller; ''Lost Circulation Technology Development Status'' by David A. Glowka; ''Downhole Memory-Logging Tools'' by Peter Lysne.

Tennyson, George P. Jr.; Dunn, James C.; Drumheller, Douglas S.; Glowka, David A.; Lysne, Peter

1992-01-01

412

Memory Hard Drive Peripherals  

E-print Network

1! CSI3131 Topics CPU Memory Hard Drive Peripherals Computing Systems OS Overview StructureDeadlocks M em ory M anagem ent Basic Memory Managermtn Virtual Memory Storage and I/O File Systems Hard Drive Management Swap I/O Management 2 Module 7: Memory Management Reading: Chapter 8 § To provide a detailed

Stojmenovic, Ivan

413

The hard metal diseases  

SciTech Connect

Hard metal is a mixture of tungsten carbide and cobalt, to which small amounts of other metals may be added. It is widely used for industrial purposes whenever extreme hardness and high temperature resistance are needed, such as for cutting tools, oil well drilling bits, and jet engine exhaust ports. Cobalt is the component of hard metal that can be a health hazard. Respiratory diseases occur in workers exposed to cobalt--either in the production of hard metal, from machining hard metal parts, or from other sources. Adverse pulmonary reactions include asthma, hypersensitivity pneumonitis, and interstitial fibrosis. A peculiar, almost unique form of lung fibrosis, giant cell interstitial pneumonia, is closely linked with cobalt exposure.66 references.

Cugell, D.W. (Department of Medicine, Northwestern University Medical School, Chicago, IL (United States))

1992-06-01

414

Diaphragm Pump With Resonant Piezoelectric Drive  

NASA Technical Reports Server (NTRS)

A diaphragm pump driven by a piezoelectric actuator is undergoing development. This pump is intended to be a prototype of lightweight, highly reliable pumps for circulating cooling liquids in protective garments and high-power electronic circuits, and perhaps for some medical applications. The pump would be highly reliable because it would contain no sliding seals or bearings that could wear, the only parts subject to wear would be two check valves, and the diaphragm and other flexing parts could be designed, by use of proven methods, for extremely long life. Because the pump would be capable of a large volumetric flow rate and would have only a small dead volume, its operation would not be disrupted by ingestion of gas, and it could be started reliably under all conditions. The prior art includes a number piezoelectrically actuated diaphragm pumps. Because of the smallness of the motions of piezoelectric actuators (typical maximum strains only about 0.001), the volumetric flow rates of those pumps are much too small for typical cooling applications. In the pump now undergoing development, mechanical resonance would be utilized to amplify the motion generated by the piezoelectric actuator and thereby multiply the volumetric flow rate. The prime mover in this pump would be a stack of piezoelectric ceramic actuators, one end of which would be connected to a spring that would be part of a spring-and-mass resonator structure. The mass part of the resonator structure would include the pump diaphragm (see Figure 1). Contraction of the spring would draw the diaphragm to the left, causing the volume of the fluid chamber to increase and thereby causing fluid to flow into the chamber. Subsequent expansion of the spring would push the diaphragm to the right, causing the volume of the fluid chamber to decrease, and thereby expelling fluid from the chamber. The fluid would enter and leave the chamber through check valves. The piezoelectric stack would be driven electrically to make it oscillate at the resonance frequency of the spring and- mass structure. This frequency could be made high enough (of the order of 400 Hz) that the masses of all components could be made conveniently small. The resonance would amplify the relatively small motion of the piezoelectric stack (a stroke of the order of 10 m) to a diaphragm stroke of the order of 0.5 mm. The exact amplification factor would depend on the rate of damping of oscillations; this, in turn, would depend on details of design and operation, including (but not limited to) the desired pressure rise and volumetric flow rate. In order to obtain resonance with large displacement, the damping rate must be low enough that the energy imparted to the pumped fluid on each stroke is much less than the kinetic and potential energy exchanged between the mass and spring during each cycle of oscillation. To minimize the power demand of the pump, a highly efficient drive circuit would be used to excite the piezoelectric stack. This circuit (see Figure 2) would amount to a special-purpose regenerative, switching power supply that would operate in a power-source mode during the part of an oscillation cycle when the excitation waveform was positive and in a power-recovery mode during the part of the cycle when the excitation waveform was negative. The circuit would include a voltage-boosting dc-to-dc converter that would convert between a supply potential of 24 Vdc and the high voltage needed to drive the piezoelectric stack. Because of the power-recovery feature, the circuit would consume little power. It should be possible to build the circuit as a compact unit, using readily available components.

Izenson, Michael G.; Kline-Schoder, Robert J.; Shimko, Martin A.

2007-01-01

415

System identification and controller design for dual actuated hard disk drive  

Microsoft Academic Search

This paper describes classical system identification and control design techniques for the dual actuated servomechanism of a hard disk drive. The dual actuated servomechanism consists of a electromechanical coarse actuator and a piezo-electric micro-actuator. The coarse actuator provides the motion required to move the read–write head from one data track to another, while the micro-actuator improves the tracking performance of

T. Suthasun; I. Mareels; A. Al-Mamun

2004-01-01

416

Settling control and performance of a dual-actuator system for hard disk drives  

Microsoft Academic Search

This paper presents a settling control of a dual-actuator system for hard disk drives. The dual-actuator system consists of a voice coil motor (VCM) as a first stage actuator and a push-pull-type piezo-electric transducer (PZT) as a second-stage actuator. The settling controller is designed in three steps. In the first step, the VCM controller is designed so that the VCM

Hidehiko Numasato; Masayoshi Tomizuka

2003-01-01

417

Dual-stage servo with on-slider PZT microactuator for hard disk drives  

Microsoft Academic Search

A dual-stage servo system with an on-slider piezoelectric (PZT) microactuator is developed for future high-density hard disk drives. The parallel control scheme is used in servo design with considerations over the stroke limitation and the hysteresis of the microactuator. Experimental results on a spin-stand with a laser Doppler vibrometer as the position sensor demonstrate that the system has a servo

Yaolong Lou; Peng Gao; Bin Qin; Guoxiao Guo; Eng-Hong Ong; A. Takada; K. Okada

2002-01-01

418

Using piezoelectric sensors for ultrasonic pulse velocity measurements in concrete  

NASA Astrophysics Data System (ADS)

The ultrasonic pulse velocity (UPV) test has been a widely used non-destructive testing method for concrete structures. However, the conventional UPV test has limitations in consistency of results and applicability in hard-to-access regions of structures. The authors explore the feasibility of embedded piezoelectric (PZT) sensors for ultrasonic measurements in concrete structures. Two PZT sensors were embedded in a reinforced concrete specimen. One sensor worked as an actuator driven by an ultrasonic pulse-receiver, and another sensor worked as a receiver. A series of ultrasonic tests were conducted to investigate the performance of the embedded sensors in crack-free concrete and concrete specimens having a surface-breaking crack under various external loadings. Signals measured by the embedded sensors show a broad bandwidth with a centre frequency around 80 kHz, and very good coherence in the frequency range from 30 to 180 kHz. Furthermore, experimental variability in ultrasonic pulse velocity and attenuation is substantially reduced compared to previously reported values from conventional UPV equipment. Findings from this study demonstrate that the embedded sensors have great potential as a low-cost solution for ultrasonic transducers for health monitoring of concrete in structures.

Kee, Seong-Hoon; Zhu, Jinying

2013-11-01

419

Engineering domain configurations for enhanced piezoelectricity in barium titanate single crystals  

E-print Network

Engineering domain configurations for enhanced piezoelectricity in barium titanate single crystals piezoelectric responses of barium titanate single crystals under different crystallographic orientations, and use it to explain the ultrahigh piezoelectric response recently observed in a 270 cut barium titanate

Li, Jiangyu

420

Structural, ferroelectric, optical properties of A-site-modified Bi0.5(Na0.78K0.22)0.5Ti0.97Zr0.03O3 lead-free piezoceramics  

NASA Astrophysics Data System (ADS)

We reported the role of A-site modification on the structural, ferroelectric, optical and electrical field-induced strain properties of Bi0.5(Na0.78K0.22)0.5Ti0.97Zr0.03O3 lead-free piezoceramics. The Li+ ions with concentration from 0 to 5 mol% were used to substitute at A-site. There was no phase transition when Li+ ions was added up to 5 mol%. The electric field-induced strain (Smax/Emax) values increased from 600 to 643 pm/V for 2 mol% Li+-added which results from distortion both rhombohedral and tetragonal phase structures. The band gap reduced from 2.88 to 2.68 eV and the saturation polarization decreased from 46.2 to 26.1 ?C/cm2 when Li+ ions concentration increased from 0 to 5 mol% respectively. We expect that this work could be helpful for further understanding the role of A-site dopants in comparison with B-site modification in lead-free Bi0.5(Na,K)0.5TiO3-based ceramics.

Quan, N. D.; Quyet, N. V.; Bac, L. H.; Thiet, D. V.; Hung, V. N.; Dung, D. D.

2015-02-01

421

Observation of magnetoelectric coupling and local piezoresponse in modified (Na0.5Bi0.5)TiO3-BaTiO3-CoFe2O4 lead-free composites.  

PubMed

Lead-free particulate multiferroic composites of [0.94(Na0.5Bi0.5)TiO3-0.06 BaTiO3]:(Co0.6Zn0.4)(Fe1.7Mn0.3)O4 were synthesized and magnetoelectric (ME) properties were studied. X-ray diffraction and microstructural studies indicated the formation of a two-phase composite system without any impurities. The shift of Raman modes corresponding to ferroelectric and ferrite phases was assigned to the induced strain amid the formation of a two-phase system, in relation to the fraction of each phase in the samples. A strong local piezoresponse and hysteresis loops observed for composites established the ferroelectric properties at a nanoscale. Magnetostriction measurements revealed values of ?11 = -10.4 and ?12 = 5.3 ppm and piezomagnetic coefficient d?11/dH = -0.0087 ppm Oe(-1) at 0.45 kOe for a composite with a ferrite concentration of 35 mol%. A maximum change of 18.5% in magnetization after electrical poling indicates a strong magnetoelectric response of the present composites followed by a direct ME coefficient of 8.2 mV cm(-1) Oe(-1). Our studies point to the fact that the present multiferroic composites having strong ME coupling are useful for lead-free electronic applications. PMID:24849499

Ramana, E Venkata; Figueiras, F; Graça, M P F; Valente, M A

2014-07-14

422

Vibration analysis of composite laminate plate excited by piezoelectric actuators.  

PubMed

Piezoelectric materials can be used as actuators for the active vibration control of smart structural systems. In this work, piezoelectric patches are surface bonded to a composite laminate plate and used as vibration actuators. A static analysis based on the piezoelectricity and elasticity is conducted to evaluate the loads induced by the piezoelectric actuators to the host structure. The loads are then employed to develop the vibration response of a simply supported laminate rectangular plate excited by piezoelectric patches subjected to time harmonic voltages. An analytical solution of the vibration response of a simply supported laminate rectangular plate under time harmonic electrical loading is obtained and compared with finite element results to validate the present approach. The effects of location and exciting frequency of piezoelectric actuators on the vibration response of the laminate plate are investigated through a parametric study. Numerical results show that modes can be selectively excited, leading to structural vibration control. PMID:23529121

Her, Shiuh-Chuan; Lin, Chi-Sheng

2013-01-01

423

Piezoelectric resonators based on self-assembled diphenylalanine microtubes  

NASA Astrophysics Data System (ADS)

Piezoelectric actuation has been widely used in microelectromechanical devices including resonance-based biosensors, mass detectors, resonators, etc. These were mainly produced by micromachining of Si and deposited inorganic piezoelectrics based on metal oxides or perovskite-type materials which have to be further functionalized in order to be used in biological applications. In this work, we demonstrate piezoelectrically driven micromechanical resonators based on individual self-assembled diphenylalanine microtubes with strong intrinsic piezoelectric effect. Tubes of different diameters and lengths were grown from the solution and assembled on a rigid support. The conducting tip of the commercial atomic force microscope was then used to both excite vibrations and study resonance behavior. Efficient piezoelectric actuation at the fundamental resonance frequency ?2.7 MHz was achieved with a quality factor of 114 for a microtube of 277 ?m long. A possibility of using piezoelectric dipeptides for biosensor applications is discussed.

Bosne, E. D.; Heredia, A.; Kopyl, S.; Karpinsky, D. V.; Pinto, A. G.; Kholkin, A. L.

2013-02-01

424

Structure-Property Study of Piezoelectricity in Polyimides  

NASA Technical Reports Server (NTRS)

High performance piezoelectric polymers are of interest to NASA as they may be useful for a variety of sensor applications. Over the past few years research on piezoelectric polymers has led to the development of promising high temperature piezoelectric responses in some novel polyimides. In this study, a series of polyimides have been studied with systematic variations in the diamine monomers that comprise the polyimide while holding the dianhydride constant. The effect of structural changes, including variations in the nature and concentration of dipolar groups, on the remanent polarization and piezoelectric coefficient is examined. Fundamental structure-piezoelectric property insight will enable the molecular design of polymers possessing distinct improvements over state-of-the-art piezoelectric polymers including enhanced polarization, polarization stability at elevated temperatures, and improved processability.

Ounaies, Zoubeida; Park, Cheol; Harrison, Joycelyn S.; Smith, Joseph G.; Hinkley, Jeffrey

1999-01-01

425

Vibration Analysis of Composite Laminate Plate Excited by Piezoelectric Actuators  

PubMed Central

Piezoelectric materials can be used as actuators for the active vibration control of smart structural systems. In this work, piezoelectric patches are surface bonded to a composite laminate plate and used as vibration actuators. A static analysis based on the piezoelectricity and elasticity is conducted to evaluate the loads induced by the piezoelectric actuators to the host structure. The loads are then employed to develop the vibration response of a simply supported laminate rectangular plate excited by piezoelectric patches subjected to time harmonic voltages. An analytical solution of the vibration response of a simply supported laminate rectangular plate under time harmonic electrical loading is obtained and compared with finite element results to validate the present approach. The effects of location and exciting frequency of piezoelectric actuators on the vibration response of the laminate plate are investigated through a parametric study. Numerical results show that modes can be selectively excited, leading to structural vibration control. PMID:23529121

Her, Shiuh-Chuan; Lin, Chi-Sheng

2013-01-01

426

Enhanced energy harvesting performance of the piezoelectric unimorph with perpendicular electrodes  

NASA Astrophysics Data System (ADS)

In this paper, we presented a combined piezoelectric effect between perpendicular faces of the piezoelectric unimorph with polarization along the thickness direction, which was decomposed into shear and transverse piezoelectric effects in analytical model. Nine types of output electrode configurations based on perpendicular electrodes were designed for the combined piezoelectric effect. In the prototype, compared with traditional transverse piezoelectric effect, the superimposed piezoelectric effect can produce 1.5 times open circuit voltage and 3.9 times power for energy harvesting.

Ma, Ming; Xia, Song; Li, Zhenrong; Xu, Zhuo; Yao, Xi

2014-07-01

427

Piezoelectric anisotropy - phase transition relations in perovskite single crystals  

Microsoft Academic Search

The orientation dependence of the longitudinal piezoelectric coefficient is investigated as a function of temperature in BaTiO3 and PbTiO3 crystals using Landau-Ginsburg-Devonshire theory. We show that a presence of the ferroelectric - ferroelectric phase transitions in BaTiO3 leads to an enhanced piezoelectric longitudinal response along nonpolar directions. The reason for this is the abrupt increase of the shear piezoelectric coefficients

Marko Budimir; Dragan Damjanovic; Nava Setter

2004-01-01

428

Elastomer degradation sensor using a piezoelectric material  

DOEpatents

A method and apparatus for monitoring the degradation of elastomeric materials is provided. Piezoelectric oscillators are placed in contact with the elastomeric material so that a forced harmonic oscillator with damping is formed. The piezoelectric material is connected to an oscillator circuit,. A parameter such as the resonant frequency, amplitude or Q value of the oscillating system is related to the elasticity of the elastomeric material. Degradation of the elastomeric material causes changes in its elasticity which, in turn, causes the resonant frequency, amplitude or Q of the oscillator to change. These changes are monitored with a peak height monitor, frequency counter, Q-meter, spectrum analyzer, or other measurement circuit. Elasticity of elastomers can be monitored in situ, using miniaturized sensors.

Olness, Dolores U. (Livermore, CA); Hirschfeld, deceased, Tomas B. (late of Livermore, CA)

1990-01-01

429

Finite element modeling of piezoelectric energy harvesters  

NASA Astrophysics Data System (ADS)

This article reports a novel finite element model of piezoelectric energy harvesters accounting for the effect of nonlinear interface circuits. The idea is to replace the energy harvesting circuit in parallel with the parasitic piezoelectric capacitance by an equivalent load impedance. This approach offers many advantages. First, the model itself can be implemented conveniently in commercial finite element softwares. Second, it directly provides system-level designs on the whole without resorting to circuit solvers. Third, the extensions to complicated structures such as array configurations are straightforward. The proposed finite element model is validated by considering the case of an array system endowed with the standard, parallel-/series-SSHI (synchronized switch harvesting on inductor) interfaces. Good agreement is found between simulation results and analytic estimates.

Wu, P. H.; Shu, Y. C.

2014-03-01

430

Piezoelectric film load cell robot collision detector  

DOEpatents

A piezoelectric load cell which can be utilized for detecting collisions and obstruction of a robot arm end effector includes a force sensing element of metallized polyvinylidene fluoride (PVDF) film. The piezoelectric film sensing element and a resilient support pad are clamped in compression between upper and lower plates. The lower plate has a central recess in its upper face for supporting the support pad and sensing element, while the upper plate has a corresponding central projection formed on its lower face for bearing on the sensing element and support pad. The upper and lower plates are dowelled together for concentric alignment and screwed together. The upper and lower plates are also adapted for mounting between the robot arm wrist and end effector. 3 figs.

Lembke, J.R.

1988-03-15

431

Piezoelectric film load cell robot collision detector  

DOEpatents

A piezoelectric load cell which can be utilized for detecting collisions and obstruction of a robot arm end effector includes a force sensing element of metallized polyvinylidene fluoride (PVDF) film. The piezoelectric film sensing element and a resilient support pad are clamped in compression between upper and lower plates. The lower plate has a central recess in its upper face for supporting the support pad and sensing element, while the upper plate has a corresponding central projection formed on its lower face for bearing on the sensing element and support pad. The upper and lower plates are dowelled together for concentric alignment and screwed together. The upper and lower plates are also adapted for mounting between the robot arm wrist and end effector.

Lembke, John R. (Overland Park, KS)

1989-04-18

432

Piezoelectric film load cell robot collision detector  

DOEpatents

A piezoelectric load cell which can be utilized for detecting collisions and obstruction of a robot arm end effector includes a force sensing element of metallized polyvinylidene fluoride (PVDF) film. The piezoelectric film sensing element and a resilient support pad are clamped in compression between upper and lower plates. The lower plate has a central recess in its upper face for supporting the support pad and sensing element, while the upper plate has a corresponding central projection formed on its lower face for bearing on the sensing element and support pad. The upper and lower plates are doweled together for concentric alignment and screwed together. The upper and lower plates are also adapted for mounting between the robot arm wrist and end effector. 3 figs.

Lembke, J.R.

1989-04-18

433

Enhanced piezoelectric performance from carbon fluoropolymer nanocomposites  

NASA Astrophysics Data System (ADS)

The piezoelectric performance of polyvinylidene fluoride (PVDF) is shown to double through the controlled incorporation of carbon nanomaterial. Specifically, PVDF composites containing carbon fullerenes (C60) and single-walled carbon nanotubes (SWNT) are fabricated over a range of compositions and optimized for their Young's modulus, dielectric constant, and d31 piezoelectric coefficient. Thermally stimulated current measurements show a large increase in internal charge and polarization in the composites over pure PVDF. The electromechanical coupling coefficients (k31) at optimal loading levels are found to be 1.84 and 2 times greater than pure PVDF for the PVDF-C60 and PVDF-SWNT composites, respectively. Such property-enhanced nanocomposites could have significant benefit to electromechanical systems employed for structural sensing, energy scavenging, sonar, and biomedical imaging.

Baur, Cary; DiMaio, Jeffrey R.; McAllister, Elliot; Hossini, Reza; Wagener, Earl; Ballato, John; Priya, Shashank; Ballato, Arthur; Smith, Dennis W.

2012-12-01

434

Novel Parametric Actuation Scheme in Piezoelectric NEMS  

NASA Astrophysics Data System (ADS)

Resonant nanoelectromechanical systems (NEMS) are attracting interest in a broad variety of applications ranging from ultrasensitive mass and force detectors to quantum limited devices. However, an efficient, fully integrated scheme for actuation and detection remains a challenge. This talk reviews our recent progress in addressing this problem. First, we obtain excellent actuation efficiency using multilayered piezoelectric nanostructures. Second, we employ the piezoelectric properties of these structures for parametric amplification of mechanical motion. Finally, we excite arrays of coupled NEMS resonators and find that their response agrees with theoretical predictions. We use such parametrically-driven resonant devices to demonstrate a thousand-fold amplitude gain, as well as a significant quality factor enhancement, both in vacuum and in air, suggesting that this scheme may provide significant improvement to sensor performance.

Karabalin, Rassul; Masmanidis, Sotiris; Lifshitz, Ron; Cross, Michael; Roukes, Michael

2007-03-01

435

Optimizing Voided Piezoelectric Polymers For Acoustic Sensors  

NASA Astrophysics Data System (ADS)

Polymer piezoelectric materials offer lower density and more flexibility than piezoelectric ceramics for applications where rugged and lightweight acoustic sensors are required. This paper discusses constraints imposed by material stiffness and dielectric constants and aims to derive a generalized closed-form solution for optimizing charged foamed polymers. Optimized solutions are reached in the limits of very large and small void fraction and permittivity ratio. The permittivity ratio is the ratio of the dielectric constants of the polymer and the material that fills the voids. Demonstrations indicate that, in the oblique asymptote, the optimized void fraction becomes equivalent to the permittivity ratio. This effort was conducted under the auspices of the Undersea Warfare Business Area (UWBA) Independent Research & Development (IRAD) Board of the Johns Hopkins University Applied Physics Laboratory (JHU/APL).

Arvelo, Juan I.

2009-07-01

436

Energy Harvesting Using PVDF Piezoelectric Nanofabric  

NASA Astrophysics Data System (ADS)

Energy harvesting using piezoelectric nanomaterial provides an opportunity for advancement towards self-powered electronics. The fabrication complexities and limited power output of these nano/micro generators have hindered these advancements thus far. This thesis presents a fabrication technique with electrospinning using a grounded cylinder as the collector. This method addresses the difficulties with the production and scalability of the nanogenerators. The non-aligned nanofibers are woven into a textile form onto the cylindrical drum that can be easily removed. The electrical poling and mechanical stretching induced by the electric field and the drum rotation increase the concentration of the piezoelectric beta phase in the PVDF nanofabric. The nanofabric is placed between two layers of polyethylene terephthalate (PET) that have interdigitated electrodes painted on them with silver paint. Applying continuous load onto the flexible PVDF nanofabric at 35Hz produces a peak voltage of 320 mV and maximum power of 2200 pW/(cm2) .

Shafii, Chakameh Shafii

437

Cantilevered probe detector with piezoelectric element  

DOEpatents

A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

2014-04-29

438

Piezoelectric films for high frequency ultrasonic transducers in biomedical applications  

PubMed Central

Piezoelectric films have recently attracted considerable attention in the development of various sensor and actuator devices such as nonvolatile memories, tunable microwave circuits and ultrasound transducers. In this paper, an overview of the state of art in piezoelectric films for high frequency transducer applications is presented. Firstly, the basic principles of piezoelectric materials and design considerations for ultrasound transducers will be introduced. Following the review, the current status of the piezoelectric films and recent progress in the development of high frequency ultrasonic transducers will be discussed. Then details for preparation and structure of the materials derived from piezoelectric thick film technologies will be described. Both chemical and physical methods are included in the discussion, namely, the sol–gel approach, aerosol technology and hydrothermal method. The electric and piezoelectric properties of the piezoelectric films, which are very important for transducer applications, such as permittivity and electromechanical coupling factor, are also addressed. Finally, the recent developments in the high frequency transducers and arrays with piezoelectric ZnO and PZT thick film using MEMS technology are presented. In addition, current problems and further direction of the piezoelectric films for very high frequency ultrasound application (up to GHz) are also discussed. PMID:21720451

Zhou, Qifa; Lau, Sienting; Wu, Dawei; Shung, K. Kirk

2011-01-01

439

Energy harvesting from low frequency applications using piezoelectric materials  

NASA Astrophysics Data System (ADS)

In an effort to eliminate the replacement of the batteries of electronic devices that are difficult or impractical to service once deployed, harvesting energy from mechanical vibrations or impacts using piezoelectric materials has been researched over the last several decades. However, a majority of these applications have very low input frequencies. This presents a challenge for the researchers to optimize the energy output of piezoelectric energy harvesters, due to the relatively high elastic moduli of piezoelectric materials used to date. This paper reviews the current state of research on piezoelectric energy harvesting devices for low frequency (0-100 Hz) applications and the methods that have been developed to improve the power outputs of the piezoelectric energy harvesters. Various key aspects that contribute to the overall performance of a piezoelectric energy harvester are discussed, including geometries of the piezoelectric element, types of piezoelectric material used, techniques employed to match the resonance frequency of the piezoelectric element to input frequency of the host structure, and electronic circuits specifically designed for energy harvesters.

Li, Huidong; Tian, Chuan; Deng, Z. Daniel

2014-12-01

440

Electrospinning of continuous piezoelectric yarns for composite application  

NASA Astrophysics Data System (ADS)

The focus of this research is to electrospin continuous yarns of piezoelectric nanofibers. Incorporating piezoelectric polymer fibers in traditional composites can add sensing and actuation capabilities, which creates a wide array of potential applications. To process nanofibers with piezoelectric properties, we are pursuing the electrospinning of poly (vinylidene fluoride) (PVDF) in DMAc. A method of electrospinning on water is used to form the continuous fibers, which are then tested using DSC, XRD, and microscopy. Through this technique, we see evidence that the non-polar ?-phase of PVDF is converted to the polar ?-phase, which is responsible for its piezoelectric behavior.

Lagoudas, Natasha C.; Ounaies, Zoubeida

2008-03-01

441

Piezoelectric biosensor with a ladder polymer substrate coating  

DOEpatents

A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor. 3 figs.

Renschler, C.L.; White, C.A.; Carter, R.M.

1998-09-29

442

Theoretical transducer properties of piezoelectric insulator FET transducers  

NASA Technical Reports Server (NTRS)

An oriented piezoelectric film incorporated in the insulator region of a silicon insulated-gate field-effect transistor (FET) results in a sensitive high-frequency strain transducer. Theory governing the transducer properties of the piezoelectric insulator FET transducer is presented. Equations are developed which relate the drain current of the device to induced polarizations of the piezoelectric layer. The highest frequency of surface strains to which the FET transducer can respond is determined by the FET frequency response - ultimately by the channel transit time. This frequency can extend to the GHz range. The low-frequency response to applied strain is determined by the dielectric relaxation frequency of the piezoelectric layer.

Greeneich, E. W.; Muller, R. S.

1975-01-01

443

Frequency modulation drive for a piezoelectric motor  

DOEpatents

A piezoelectric motor has peak performance at a specific frequency f.sub.1 that may vary over a range of frequencies. A drive system is disclosed for operating such a motor at peak performance without feedback. The drive system consists of the motor and an ac source connected to power the motor, the ac source repeatedly generating a frequency over a range from f.sub.1 -.DELTA.x to f.sub.1 +.DELTA.y.

Mittas, Anthony (Albuquerque, NM)

2001-01-01

444

Modeling of a piezoelectric micro-scanner  

Microsoft Academic Search

Micro-scanners have been widely used in many optical applications. The micro-scanner presented in this paper uses multimorph-type bending actuators to tilt a square plate mirror. This paper presents a complete analytical model of the piezoelectric micro-scanner. This theoretical model based on strength of material equations calculates the force generated by the multimorphs on the mirror, the profile of the structure

A. Chaehoi; M. Begbie; D. Cornez; K. Kirk

2008-01-01

445

Multilayer Piezoelectric Ceramic Vibrator with Internal Electrodes  

Microsoft Academic Search

Multilayer piezoelectric vibrators made from high mechanical quality factor (Q m) PbZrTiO3 ceramic material with internal electrodes have been investigated for application to ultrasonic devices. The existence of internal electrodes activates the ceramic sintering reaction and as a result, cofiring of the the multilayer vibrator at a lower temperature becomes possible. Multilayer vibrators with 2-9 layers of internal electrodes were

Yoshiaki Fuda; Hiroshi Ono; Futoshi Shiotani; Katsunori Kumasaka

1995-01-01

446

Piezoelectric ultrasonic micro\\/milli-scale actuators  

Microsoft Academic Search

A growing demand for actuators with a volume of less than 1mm3 has driven researchers to produce a varied range of micro\\/milli-scale designs. By examining the underlying physics of the actuator operation we are able to demonstrate why piezoelectric ultrasonic actuators have the greatest potential to meet this need. Moreover, it allows us to create a new classification system for

B. Watson; J. Friend; L. Yeo

2009-01-01

447

Mechanically amplified large displacement piezoelectric actuators  

Microsoft Academic Search

This paper deals with large displacement actuators based on mechanically amplified movements of pre-stressed piezoelectric disks. The bridge-type amplifier structures were made of laser cut polymer laminates fold to certain geometries to accomplish enhanced displacement of the input translation. Optimization of the lever lengths and their positions were carried out using computer-assisted design (by AutoCAD) and mathematical calculations (by MATLAB).

J. Juuti; K. Kordás; R. Lonnakko; V.-P. Moilanen; S. Leppävuori

2005-01-01

448

A strain amplifying piezoelectric MEMS actuator  

Microsoft Academic Search

A micro-scale, high-force, large displacement and low-voltage piezoelectric actuator has been developed using a compact strain amplifying flextensional mechanism. The device is fabricated using an SU-8 beam structure as an external amplifying mechanism for a thin-film PZT strip (area 11.4 × 10-4 cm2, thickness 0.4 µm) sandwiched between Pt top and bottom electrodes. Each actuator 'cell' can be arrayed in

Nicholas J. Conway; Zachary J. Traina; Sang-Gook Kim

2007-01-01

449

A strain amplifying piezoelectric MEMS actuator  

Microsoft Academic Search

A micro-scale, high-force, large displacement and low-voltage piezoelectric actuator has been developed using a compact strain amplifying flextensional mechanism. The device is fabricated using an SU-8 beam structure as an external amplifying mechanism for a thin-film PZT strip (area 11.4 × 10?4 cm2, thickness 0.4 µm) sandwiched between Pt top and bottom electrodes. Each actuator ‘cell’ can be arrayed in

Nicholas J Conway; Zachary J Traina; Sang-Gook Kim

2007-01-01

450

Piezoelectrically actuated time-averaged atomic microtraps  

NASA Astrophysics Data System (ADS)

We present a scheme for creating tight and adiabatic time-averaged atom-traps through the piezoelectric actuation of nanomagnetic structures. We show that potentials formed by the circular translation of magnetic structures have several advantages over conventional rotating-field techniques, particularly for high trap frequencies. As the magnitude of the actuation is changed, the trapping potential can be changed adiabatically between harmonic 3D confinement and a toroidal trap.

West, A. D.; Wade, C. G.; Weatherill, K. J.; Hughes, I. G.

2012-07-01

451

Piezoelectric Actuators On A Cold Finger  

NASA Technical Reports Server (NTRS)

Developmental system for active suppression of vibrations of cold finger includes three piezoelectric actuators bonded to outer surface. Actuators used to suppress longitudinal and lateral vibrations of upper end of cold finger by applying opposing vibrations. Cold finger in question is part of a cryogenic system associated with an infrared imaging detector. When fully developed, system would be feedback sensor/control/actuator system automatically adapting to changing vibrational environment and suppresses pressure-induced vibrations by imposing compensatory vibrations via actuators.

Kuo, Chin-Po; Garba, John A.; Glaser, Robert J.

1995-01-01

452

Piezoelectric-based apparatus for strain tuning  

NASA Astrophysics Data System (ADS)

We report the design and construction of piezoelectric-based apparatus for applying continuously tuneable compressive and tensile strains to test samples. It can be used across a wide temperature range, including cryogenic temperatures. The achievable strain is large, so far up to 0.23% at cryogenic temperatures. The apparatus is compact and compatible with a wide variety of experimental probes. In addition, we present a method for mounting high-aspect-ratio samples in order to achieve high strain homogeneity.

Hicks, Clifford W.; Barber, Mark E.; Edkins, Stephen D.; Brodsky, Daniel O.; Mackenzie, Andrew P.

2014-06-01

453

Piezoelectric cantilevers energy harvesting in MEMS technique  

NASA Astrophysics Data System (ADS)

Piezoelectric cantilevers energy harvesting made by micro-electromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed cantilevers energy harvesting are featured with resonate frequency and power output in microwatt level, which is sufficient to the self-supportive sensors for in-service integrity monitoring of large social and environmental infrastructures at remote locations. In this paper, piezoelectric energy harvesting based on thick-film piezoelectric cantilevers is investigated to resonate at specific frequencies of an external vibration energy source, which creating electrical energy via the piezoelectric effect. Our cantilever device has a multiple structure with a proof mass added to the end. The thick film lead zirconate titanate Pb(Zr,Ti)O3 (PZT) coated on the top of Au/Cr/SiO2/Si substrates by sol-gel-spin method. The thickness of the PZT membrane was up to 2?m and the cantilevers substrates thickness 50?m, wideness 1.5mm, length 4mm. The Au/Ti top electrode is patterned on top of the sol-gel-spin coated PZT thick film in order to employ the d31 mode. The prototype energy generator has a measured performance of 0.74?W effective electrical power, and 4.93 DC output voltages to resistance load. The effect of proof mass, beam shape and damping on the power generating performance are modeled to provide a design guideline for maximum power harvesting from environmentally available low frequency vibrations. A multiple structure cantilever is designed to achieve compactness, low resonant frequency and minimum damping coefficient, simultaneously. This device is promising to support networks of ultra-low-power sensor.

Shang, Yingqi; Qiu, Chengjun; Liu, Hongmei; Chen, Xiaojie; Qu, Wei; Dou, Yanwei

2011-11-01

454

Piezoelectric cantilevers energy harvesting in MEMS technique  

NASA Astrophysics Data System (ADS)

Piezoelectric cantilevers energy harvesting made by micro-electromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed cantilevers energy harvesting are featured with resonate frequency and power output in microwatt level, which is sufficient to the self-supportive sensors for in-service integrity monitoring of large social and environmental infrastructures at remote locations. In this paper, piezoelectric energy harvesting based on thick-film piezoelectric cantilevers is investigated to resonate at specific frequencies of an external vibration energy source, which creating electrical energy via the piezoelectric effect. Our cantilever device has a multiple structure with a proof mass added to the end. The thick film lead zirconate titanate Pb(Zr,Ti)O3 (PZT) coated on the top of Au/Cr/SiO2/Si substrates by sol-gel-spin method. The thickness of the PZT membrane was up to 2?m and the cantilevers substrates thickness 50?m, wideness 1.5mm, length 4mm. The Au/Ti top electrode is patterned on top of the sol-gel-spin coated PZT thick film in order to employ the d31 mode. The prototype energy generator has a measured performance of 0.74?W effective electrical power, and 4.93 DC output voltages to resistance load. The effect of proof mass, beam shape and damping on the power generating performance are modeled to provide a design guideline for maximum power harvesting from environmentally available low frequency vibrations. A multiple structure cantilever is designed to achieve compactness, low resonant frequency and minimum damping coefficient, simultaneously. This device is promising to support networks of ultra-low-power sensor.

Shang, Yingqi; Qiu, Chengjun; Liu, Hongmei; Chen, Xiaojie; Qu, Wei; Dou, Yanwei

2012-04-01

455

Plucked piezoelectric bimorphs for energy harvesting applications  

NASA Astrophysics Data System (ADS)

The modern drive towards mobility and wireless devices is motivating intense research in energy harvesting (EH) technologies. In an effort to reduce the battery burden of people, we are investigating a novel piezoelectric wearable energy harvester. As piezoelectric EH is significantly more effective at high frequencies, in opposition to the characteristically low-frequency human activities, we propose the use of an up-conversion strategy analogous to the pizzicato musical technique. In order to guide the design of such harvester, we have modelled with Finite Elements (FE) the response and power generation of a piezoelectric bimorph while it is "plucked", i.e. deflected, then released and permitted to vibrate freely. An experimental rig has been devised and set up to reproduce the action of the bimorph in the harvester. Measurements of the voltage output and the energy dissipated across a series resistor are reported and compared with the FE predictions. As the novel harvester will feature a number of bimorphs, each plucked tens of times per step, we predict a total power output of several mW, with imperceptible effect on the wearer's gait.

Pozzi, Michele; Zhu, Meiling

2011-06-01

456

Hybrid Piezoelectric/Fiber-Optic Sensor Sheets  

NASA Technical Reports Server (NTRS)

Hybrid piezoelectric/fiber-optic (HyPFO) sensor sheets are undergoing development. They are intended for use in nondestructive evaluation and long-term monitoring of the integrity of diverse structures, including aerospace, aeronautical, automotive, and large stationary ones. It is anticipated that the further development and subsequent commercialization of the HyPFO sensor systems will lead to economic benefits in the form of increased safety, reduction of life-cycle costs through real-time structural monitoring, increased structural reliability, reduction of maintenance costs, and increased readiness for service. The concept of a HyPFO sensor sheet is a generalization of the concept of a SMART Layer(TradeMark), which is a patented device that comprises a thin dielectric film containing an embedded network of distributed piezoelectric actuator/sensors. Such a device can be mounted on the surface of a metallic structure or embedded inside a composite-material structure during fabrication of the structure. There is has been substantial interest in incorporating sensors other than piezoelectric ones into SMART Layer(TradeMark) networks: in particular, because of the popularity of the use of fiber-optic sensors for monitoring the "health" of structures in recent years, it was decided to incorporate fiber-optic sensors, giving rise to the concept of HyPFO devices.

Lin, Mark; Qing, Xinlin

2004-01-01

457

Piezoelectric energy harvester under parquet floor  

NASA Astrophysics Data System (ADS)

The design, fabrication and testing of piezoelectric energy harvesting modules for floors is described. These modules are used beneath a parquet floor to harvest the energy of people walking over it. The harvesting modules consist of monoaxial stretched PVDF-foils. Multilayer modules are built up as roller-type capacitors. The fabrication process of the harvesting modules is simple and very suitable for mass production. Due to the use of organic polymers, the modules are characterized by a great flexibility and the possibility to create them in almost any geometrical size. The energy yield was determined depending on the dynamic loading force, the thickness of piezoelectric active material, the size of the piezoelectric modules, their alignment in the walking direction and their position on the floor. An increase of the energy yield at higher loading forces and higher thicknesses of the modules was observed. It was possible to generate up to 2.1mWs of electric energy with dynamic loads of 70kg using a specific module design. Furthermore a test floor was assembled to determine the influence of the size, alignment and position of the modules on the energy yield.

Bischur, E.; Schwesinger, N.

2011-03-01

458

Snap-through piezoelectric energy harvesting  

NASA Astrophysics Data System (ADS)

Snap-through mechanism is employed to harvest electricity from random vibration through piezoelectricity. The random excitation is assumed to be Gaussian white noise. The snap-through piezoelectric energy harvester possesses the bistability. For small-amplitude vibration in a potential well, the Ito stochastic differential equation of the electromechanical coupling system is derived from the Taylor approximation at a stable equilibrium point. The method of the moment differential equations is applied to determine the statistical moments of the displacement response and the output voltage. The effects of the system parameters on the output voltage and the output power are examined. The approximate analytical outcomes are qualitatively and quantitatively supported by the numerical simulations. For large-amplitude interwell motion, the effects of the parameters on the output voltage and the output power are numerically investigated. Nonlinearity produced by the snap-through improves energy harvesting so that the snap-through piezoelectric energy harvester can outperform the linear energy harvester in the similar size under Gaussian white noise excitations.

Jiang, Wen-An; Chen, Li-Qun

2014-09-01

459

Geometrically nonlinear behavior of piezoelectric laminated plates  

NASA Astrophysics Data System (ADS)

The geometrically nonlinear behavior of piezo-laminated plates actuated with isotropic or anisotropic piezoelectric layers is analytically investigated. The analytical model is derived using the variational principle of virtual work along with the lamination and plate theories, the von Karman large displacement and moderate rotation kinematic relations, and the anisotropic piezoelectric constitutive laws. A solution strategy that combines the approach of the method of lines, the advantages of the finite element concept, and the variational formulation is developed. This approach yields a set of nonlinear ordinary differential equations with nonlinear boundary conditions, which are solved using the multiple-shooting method. Convergence and verification of the model are examined through comparison with linear and nonlinear results of other approximation methods. The nonlinear response of two active plate structures is investigated numerically. The first plate is actuated in bending using monolithic piezoceramic layers and the second one is actuated in twist using macro-fiber composites. The results quantitatively reveal the complicated in-plane stress state associated with the piezoelectric actuation and the geometrically nonlinear coupling of the in-plane and out-of-plane responses of the plate. The influence of the nonlinear effects ranges from significant stiffening in certain combinations of electrical loads and boundary conditions to amplifications of the induced deflections in others. The paper closes with a summary and conclusions.

Rabinovitch, Oded

2005-08-01

460

Integration of bulk piezoelectric materials into microsystems  

NASA Astrophysics Data System (ADS)

Bulk piezoelectric ceramics, compared to deposited piezoelectric thin-films, provide greater electromechanical coupling and charge capacity, which are highly desirable in many MEMS applications. In this thesis, a technology platform is developed for wafer-level integration of bulk piezoelectric substrates on silicon, with a final film thickness of 5-100microm. The characterized processes include reliable low-temperature (200°C) AuIn diffusion bonding and parylene bonding of bulk-PZT on silicon, wafer-level lapping of bulk-PZT with high-uniformity (+/-0.5microm), and low-damage micro-machining of PZT films via dicing-saw patterning, laser ablation, and wet-etching. Preservation of ferroelectric and piezoelectric properties is confirmed with hysteresis and piezo-response measurements. The introduced technology offers higher material quality and unique advantages in fabrication flexibility over existing piezoelectric film deposition methods. In order to confirm the preserved bulk properties in the final film, diaphragm and cantilever beam actuators operating in the transverse-mode are designed, fabricated and tested. The diaphragm structure and electrode shapes/sizes are optimized for maximum deflection through finite-element simulations. During tests of fabricated devices, greater than 12microm PP displacement is obtained by actuation of a 1mm2 diaphragm at 111kHz with <7mW power consumption. The close match between test data and simulation results suggests that the piezoelectric properties of bulk-PZT5A are mostly preserved without any necessity of repolarization. Three generations of resonant vibration energy harvesters are designed, simulated and fabricated to demonstrate the competitive performance of the new fabrication process over traditional piezoelectric deposition systems. An unpackaged PZT/Si unimorph harvester with 27mm3 active device volume produces up to 205microW at 1.5g/154Hz. The prototypes have achieved the highest figure-of-merits (normalized-power-density x bandwidth) amongst previously reported inertial energy harvesters. The fabricated energy harvester is utilized to create an autonomous energy generation platform in 0.3cm3 by system-level integration of a 50-80% efficient power management IC, which incorporates a supply-independent bias circuitry, an active diode for low-dropout rectification, a bias-flip system for higher efficiency, and a trickle battery charger. The overall system does not require a pre-charged battery, and has power consumption of <1microW in active-mode (measured) and <5pA in sleep-mode (simulated). Under lg vibration at 155Hz, a 70mF ultra-capacitor is charged from OV to 1.85V in 50 minutes.

Aktakka, Ethem Erkan

461

Three-dimensional piezoelectric boundary elements  

NASA Astrophysics Data System (ADS)

The strong coupling between mechanical and electrical fields in piezoelectric ceramics makes them appropriate for use as actuation devices; as a result, they are an important part of the emerging technologies of smart materials and structures. These piezoceramics are very brittle and susceptible to fracture, especially under the severe loading conditions which may occur in service. A significant portion of the applications under investigation involve dynamic loading conditions. Once a crack is initiated in the piezoelectric medium, the mechanical and electrical fields can act to drive the crack growth. Failure of the actuator can result from a catastrophic fracture event or from the cumulative effects of cyclic fatigue. The presence of these cracks, or other types of material defects, alter the mechanical and electrical fields inside the body. Specifically, concentrations of stress and electric field are present near a flaw and can lead to material yielding or localized depoling, which in turn can affect the sensor/actuator performance or cause failure. Understanding these effects is critical to the success of these smart structures. The complex coupling behavior and the anisotropy of the material makes the use of numerical methods necessary for all but the simplest problems. To this end, a three-dimensional boundary element method program is developed to evaluate the effect of flaws on these piezoelectric materials. The program is based on the linear governing equations of piezoelectricity and relies on a numerically evaluated Green's function for solution. The boundary element method was selected as the evaluation tool due to its ability to model the interior domain exactly. Thus, for piezoelectric materials the coupling between mechanical and electrical fields is not approximated inside the body. Holes in infinite and finite piezoceramics are investigated, with the localized stresses and electric fields clearly developed. The accuracy of the piezoelectric boundary element method is demonstrated with two problems: a two-dimensional circular void and a three-dimensional spherical cavity, both inside infinite solids. Application of the program to a finite body with a centered, spherical void illustrates the complex nature of the mechanical and electrical coupling. Mode I fracture is also examined, combining the linear boundary element solution with the modified crack closure integral to determine strain energy release rates. Experimental research has shown that the strain, rather than the tot