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Sample records for buffered metal substrates

  1. Buffer layers on metal alloy substrates for superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Quanxi; Foltyn, Stephen R.; Arendt, Paul N.; Groves, James R.

    2004-10-05

    An article including a substrate, at least one intermediate layer upon the surface of the substrate, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the at least one intermediate layer, and a layer of a SrRuO.sub.3 buffer material upon the oriented cubic oxide material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon the layer of a SrRuO.sub.3 buffer material layer. With a HTS top-layer of YBCO upon at least one layer of the SrRuO.sub.3 buffer material in such an article, J.sub.c 's of up to 1.3.times.10.sup.6 A/cm.sup.2 have been demonstrated with projected I.sub.c 's of over 200 Amperes across a sample 1 cm wide.

  2. Buffer layers on metal alloy substrates for superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Quanxi; Foltyn, Stephen R.; Arendt, Paul N.; Groves, James R.

    2004-06-29

    An article including a substrate, a layer of an inert oxide material upon the surface of the substrate, a layer of an amorphous oxide or oxynitride material upon the inert oxide material layer, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the amorphous oxide material layer, and a layer of a SrRuO.sub.3 buffer material upon the oriented cubic oxide material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon the layer of a SrRuO.sub.3 buffer material layer. With a HTS top-layer of YBCO upon at least one layer of the SrRuO.sub.3 buffer material in such an article, J.sub.c 's of up to 1.3.times.10.sup.6 A/cm.sup.2 have been demonstrated with projected IC's of over 200 Amperes across a sample 1 cm wide.

  3. AC losses in arrays of superconducting strips on buffered metallic substrates

    International Nuclear Information System (INIS)

    Full text: The effect of subdividing superconducting YBCO films on YSZ-buffered hastelloy substrates into arrays of parallel strips on the AC loss was investigated theoretically and experimentally. The hysteretic and eddy current contributions to the AC loss of such arrays were calculated as a function of temperature and applied AC magnetic field amplitude and frequency for different width and lateral separation of the strips as well as substrate and film thickness. It is shown that subdivision of a strip into sub-strips reduces the hysteretic loss proportional to the number of sub-strips. Measurements of the loss component of the AC susceptibility, X'', confirm the theoretical predictions. When the film is subdivided into N parallel strips, the frequency-independent hysteretic contribution to X'', which is dominant at lower frequencies (f ∼ 100 Hz), decreases to 1/N of its original value. As the strips become wider or their separation becomes smaller, the hysteretic X'' increases. The eddy current contribution to X'', which originates from the metallic substrate, becomes prominent as the frequency increases, approaching a linear frequency dependence at high frequencies. Its weak temperature dependence reflects that of the hastelloy resistivity

  4. Growth and Characterization of Doped CeO2 Buffers on Ni-W Substrates for Coated Conductors Using Metal Organic Deposition Method

    Institute of Scientific and Technical Information of China (English)

    WANG Yao; ZHOU Lian; YU Zeming; LI Chengshan; LI Jinshan; JIN Lihu; LU Yafen

    2012-01-01

    CeO2 and Ce0 8Mo2O2-d films (M =Mn,Y,Gd,Sin,Nd and La) with (001) preferred orientation have been prepared on biaxially textured Ni-W substrates by metal organic decomposition (MOD) method.The factors influencing the formation of cracks on the surface of these CeO2 and doped CeO2 films on Ni-W substrates were explored by X-ray diffraction (XRD),scanning electron microscopy (SEM) analysis,atomic force microscopy (AFM) and differential scanning calorimetry (DSC).The results indicate that many factors,such as the change of the ionic radii of doping cations,the transformation of crystal structure and the formation of oxygen vacancies in lattices at high annealing temperature,may be related to the formation of cracks on the surface of these films.However,the crack formation shows no dependence on the crystal lattice mismatch degree of the films with Ni-W substrates.Moreover,the suppression of surface cracks is related to the change of intrinsic elasticity of CeO2 film with doping of cations with a larger radius.SEM and AFM investigations of Ce08Mo2O2-d(M =Y,Gd,Sm,Nd and La) films reveal the dense,smooth and crack-free microstructure,and their lattice parameters match well with that of YBCO,illuminating that they are potentially suitable to be as buffer layer,especially as cap layer in multi-layer architecture of buffer layer for coated conductors.

  5. Structural and magentic characterization of rare earth and transition metal films grown on epitaxial buffer films on semiconductor substrates

    International Nuclear Information System (INIS)

    Structural and magnetic data are presented and discussed for epitaxial films of rare earth metals (Dy, Ho, Er) on LaF3 films on the GaAs(TTT) surface and Fe on Ag films on the GaAs(001) surface. Both systems exhibit unusual structural characteristics which influence the magnetic properties of the metal films. In the case of rare earth epitaxy on LaF3 the authors present evidence for epitaxy across an incommensurate or discommensurate interface. Coherency strain is not transmitted into the metal which behaves much like bulk crystals of the rare earths. In the case of Fe films, tilted epitaxy and long-range coherency strain are confirmed by X- ray diffractometry. Methods of controlling some of these structural effects by modifying the epitaxial structures are presented

  6. Substrate dependent buffer-layer assisted growth of nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Honolka, Jan; Sessi, Violetta; Hertenberger, Simon; Kern, Klaus [Max-Planck Institute for Solid State Research, Stuttgart (Germany); Zhang, Jian [Max-Planck Institute for Solid State Research, Stuttgart (Germany); School of Material Science and Engineering, Hebei University of Technology, TianJin (China); Enders, Axel [Department of Physics and Astronomy and NCMN, University of Nebraska, Lincoln, Nebraska (United States)

    2010-05-15

    The role of the substrate on the morphology of nanometer size clusters fabricated by buffer layer assisted growth (BLAG) was studied using scanning tunneling microscopy. Clusters of Fe and Co were deposited on Ag(111), Cu(100), Rh(111), and Pt(111) surfaces using identical BLAG parameters, which are temperature, as well as metal and buffer layer coverage. Semi-hemispherical clusters are found on Ag(111) and Cu(100), while flat monolayer high islands are observed on Rh(111) and Pt(111) due to complete wetting. The results of this study are in agreement with the common notion that BLAG is useful to deposit clusters of virtually any material on any substrate, however, the shape, size, and lateral distribution of the resulting clusters depend strongly on the substrate surface free energy and diffusion processes. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Effect of maleic anhydride-aniline derivative buffer layer on the properties of flexible substrate heterostructures: Indium tin oxide/nucleic acid base/metal

    Energy Technology Data Exchange (ETDEWEB)

    Stanculescu, A., E-mail: sanca@infim.ro [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, M. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, G.; Mihailescu, I.N. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, 077125, Bucharest-Magurele (Romania); Girtan, M. [Laboratoire de Photonique d' Angers, Universite d' Angers, 2, Bd. Lavoisier, 49045, Angers (France); Preda, N. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Albu, A.-M. [Department of Polymer Science, University ' Politehnica' of Bucharest, Bucharest (Romania); Stanculescu, F. [University of Bucharest, Faculty of Physics, Str. Atomistilor nr.405, P.O. Box MG-11, Bucharest-Magurele, 077125 (Romania)

    2011-12-01

    This paper presents some investigations on the properties of guanine (G) and cytosine (C) based heterostructures deposited on flexible substrates. The effects of two types of maleic anhydride-aniline derivatives (maleic anhydride-cyano aniline or maleic anhydride-2,4 dinitroaniline) buffer layer, deposited between indium tin oxide and (G) or (C) layer, on the optical and electrical properties of the heterostructures have been identified. The heterostructures containing a film of maleic anhydride-2,4 dinitroaniline have shown a good transparency and low photoluminescence in visible range. This buffer layer has determined an increase in the conductance only in the heterostructures based on (G) and (C) deposited on biaxially-oriented polyethylene terephthalate substrate.

  8. Fabrication of Y1-xRE xBa2Cu3O y films on single crystalline substrates and IBAD buffered metallic tapes by advanced TFA-MOD process

    International Nuclear Information System (INIS)

    We fabricated Y1-xSm xBa2Cu3O y and YSm xBa2Cu3O y (YSmBCO) films on SrTiO3 (STO) single crystalline substrates and IBAD buffered metallic tapes (PLD-CeO2/IBAD-GZO/Hastelloy) by the advanced TFA-MOD process by mixing TFA salts of Y, Sm, Ba and Cu naphthenate, and tried to improve the superconductivity properties compared with those of the pure YBa2Cu3O7-δ (YBCO). As a result, J c values of Y1-xSm xBa2Cu3O y films with x = 0.05 or 0.3, which were fabricated on STO substrates, were improved under the high magnetic fields compared with those of the YBCO without substitution. However, Sm segregation was detected near the STO substrate which was obtained by the TEM-EDS (transmission electron microscopy-energy-dispersive X-ray spectroscopy) analysis. On the other hand, Y1-xSm xBa2Cu3O y films with x = 0.05 and YSm xBa2Cu3O y films with x = 0.3, which were fabricated on IBAD buffered metallic substrates, also improved I c value under the high magnetic fields compared with those of the YBCO without substitution. Moreover, from the TEM-EDS analysis, Y or Sm segregation was not found. The difference in the Sm segregation behavior between the film on STO and CeO2 buffered substrates could be explained by the difference in the ratios of the misfit parameters between YBCO/substrate and SmBCO/substrate. Additionally, it was considered that the above phenomenon might be unique in the MOD system and could not be observed in the PLD system, because of the difference in the crystal growth mechanism. In the film of YSm0.3Ba2Cu3O y, we observed the grains of (Y, Sm)2O3 and (Y, Sm)2Cu2O5 by TEM observation. We will further investigate the origin of pinning centers

  9. Elastic strain relief in nitridated Ga metal buffer layers for epitaxial GaN growth

    International Nuclear Information System (INIS)

    Gallium nitride epitaxial layers were grown on sapphire by molecular-beam epitaxy using nitridated gallium metal films as buffer layers. The mechanical properties of the buffer layers were investigated and correlated with their chemical composition as determined by synchrotron radiation photoelectron spectroscopy. Biaxial tension experiments were performed by bending the substrates in a pressure cell designed for simultaneous photoluminescence measurements. The shift of the excitonic luminescence peak was used to determine the stress induced in the main GaN epilayer. The fraction of stress transferred from substrate to main layer was as low as 27% for samples grown on nitridated metal buffer layers, compared to nearly 100% for samples on conventional low-temperature GaN buffer layers. The efficiency of stress relief increased in proportion to the fraction of metallic Ga in the nitridated metal buffer layers. These findings suggest GaN films containing residual metallic Ga may serve as compliant buffer layers for heteroepitaxy

  10. Fabrication and properties of epitaxial buffer layers on nonmagnetic textured Ni based alloy substrates

    International Nuclear Information System (INIS)

    Biaxially aligned YBCO thick films on oxide buffered metallic substrates is a promising route toward the fabrication of superconducting tapes operating at liquid nitrogen temperature. The role of buffer layer is to reduce the lattice mismatch between the substrate and the YBCO film, to adapt the thermal expansion coefficient, to hamper the diffusion of Ni in YBCO film and to prevent the oxidation of the metallic substrate surface. This paper presents a study regarding CeO2 buffer layer deposition on a new nonmagnetic (001)[100] textured Ni-V alloy substrates. The deposition of CeO2 was performed by both pulsed laser ablation and e-beam evaporation techniques. The θ-2θ X-ray diffraction pattern mainly exhibits the (00 ell) peaks of CeO2, indicating that the films are epitaxially grown with the c axis perpendicular to the substrate. Rocking curves through the CeO2 (002) peak have a FWHM of about 6 degree. The SEM studies have shown that the surface is smooth, continuous and free of cracks. Texture analysis reveals a good in-plane orientation for the ablated CeO2 film, whereas the electron beam evaporated CeO2 shows two textures in the growth plane. Further efforts are focused on the deposition of YBCO thick film on the as buffered nonmagnetic metallic substrate

  11. Fabrication and properties of epitaxial buffer layers on nonmagnetic textured Ni based alloy substrates

    Energy Technology Data Exchange (ETDEWEB)

    Celentano, G.; Boffa, V.; Ciontea, L.; Fabbri, F.; Galluzzi, V.; Mancini, A.; Petrisor, T. [ENEA Centro Ricerche Frascati, Rome (Italy); Ceresara, S. [Centro Innovazione Lecco (Italy); Scardi, P. [Univ. di Trento (Italy). Dipt. di Ingegneria dei Materiali

    1999-04-20

    Biaxially aligned YBCO thick films on oxide buffered metallic substrates is a promising route toward the fabrication of superconducting tapes operating at liquid nitrogen temperature. The role of buffer layer is to reduce the lattice mismatch between the substrate and the YBCO film, to adapt the thermal expansion coefficient, to hamper the diffusion of Ni in YBCO film and to prevent the oxidation of the metallic substrate surface. This paper presents a study regarding CeO{sub 2} buffer layer deposition on a new nonmagnetic (001)[100] textured Ni-V alloy substrates. The deposition of CeO{sub 2} was performed by both pulsed laser ablation and e-beam evaporation techniques. The {theta}-2{theta} X-ray diffraction pattern mainly exhibits the (00{ell}) peaks of CeO{sub 2}, indicating that the films are epitaxially grown with the c axis perpendicular to the substrate. Rocking curves through the CeO{sub 2} (002) peak have a FWHM of about 6{degree}. The SEM studies have shown that the surface is smooth, continuous and free of cracks. Texture analysis reveals a good in-plane orientation for the ablated CeO{sub 2} film, whereas the electron beam evaporated CeO{sub 2} shows two textures in the growth plane. Further efforts are focused on the deposition of YBCO thick film on the as buffered nonmagnetic metallic substrate.

  12. MgO buffer layers on rolled nickel or copper as superconductor substrates

    Science.gov (United States)

    Paranthaman, Mariappan; Goyal, Amit; Kroeger, Donald M.; List, III, Frederic A.

    2001-01-01

    Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

  13. Method for making MgO buffer layers on rolled nickel or copper as superconductor substrates

    Science.gov (United States)

    Paranthaman, Mariappan; Goyal, Amit; Kroeger, Donald M.; List, III, Frederic A.

    2002-01-01

    Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

  14. Clad buffer rod sensors for liquid metals

    International Nuclear Information System (INIS)

    Clad buffer rods, consisting of a core and a cladding, have been developed for ultrasonic monitoring of liquid metal processing. The cores of these rods are made of low ultrasonic-loss materials and the claddings are fabricated by thermal spray techniques. The clad geometry ensures proper ultrasonic guidance. The lengths of these rods ranges from tens of centimeters to 1m. On-line ultrasonic level measurements in liquid metals such as magnesium at 700 deg C and aluminum at 960 deg C are presented to demonstrate their operation at high temperature and their high ultrasonic performance. A spherical concave lens is machined at the rod end for improving the spatial resolution. High quality ultrasonic images have been obtained in the liquid zinc at 600 deg C. High spatial resolution is needed for the detection of inclusions in liquid metals during processing. We also show that the elastic properties such as density, longitudinal and shear wave velocities of liquid metals can be measured using a transducer which generates and receives both longitudinal and shear waves and is mounted at the end of a clad buffer rod. (author)

  15. Substrate surface treatment and YSZ buffer layers by IBAD method for coated conductors

    International Nuclear Information System (INIS)

    In this work, an Ion Beam Assisted Deposition (IBAD) system was utilized to fabricate Yttria-Stabilized Zirconia (YSZ) template films for coated conductors. The surface of the Hastelloy C276 substrate was modified by rolling and electropolishing. The effect of the electropolishing parameters of the substrate on the texture of the YSZ buffer layers was studied. The electropolishing current and time were optimized for short samples of 1 cmx1 cm square shape as 1 A and 60 s, respectively. And the relationship between the roughness of the substrate surface and the texture of the YSZ layer is discussed. Reel-to-reel metal tape moving apparatus was installed and used to produce meter-long buffer layer for coated conductors. The YSZ template film was deposited by IBAD method on meter-long Hastelloy tape with tape shifting speed of 15-20 m/h, and the thickness of the buffer layer was up to about 1.7 μm. The Hastelloy substrate surface was measured by Atomic Force Microscope. The thickness of the YSZ films over length was measured by Thermal Field Emission Scan Electronic Microscopy. X Ray Diffraction Ω-scan and φ-scan measurements were performed in order to examine the out-of-plane and in-plane texture of the YSZ buffer layers, respectively.

  16. Substrate surface treatment and YSZ buffer layers by IBAD method for coated conductors

    Science.gov (United States)

    Feng, F.; Liu, R.; Chen, H.; Shi, K.; Wang, Z.; Wu, W.; Han, Z.

    2009-10-01

    In this work, an Ion Beam Assisted Deposition (IBAD) system was utilized to fabricate Yttria-Stabilized Zirconia (YSZ) template films for coated conductors. The surface of the Hastelloy C276 substrate was modified by rolling and electropolishing. The effect of the electropolishing parameters of the substrate on the texture of the YSZ buffer layers was studied. The electropolishing current and time were optimized for short samples of 1 cm×1 cm square shape as 1 A and 60 s, respectively. And the relationship between the roughness of the substrate surface and the texture of the YSZ layer is discussed. Reel-to-reel metal tape moving apparatus was installed and used to produce meter-long buffer layer for coated conductors. The YSZ template film was deposited by IBAD method on meter-long Hastelloy tape with tape shifting speed of 15-20 m/h, and the thickness of the buffer layer was up to about 1.7 μm. The Hastelloy substrate surface was measured by Atomic Force Microscope. The thickness of the YSZ films over length was measured by Thermal Field Emission Scan Electronic Microscopy. X Ray Diffraction Ω-scan and ϕ-scan measurements were performed in order to examine the out-of-plane and in-plane texture of the YSZ buffer layers, respectively.

  17. Substrate surface treatment and YSZ buffer layers by IBAD method for coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Feng, F. [Department of Physics, Tsinghua University, Beijing 100084 (China); Liu, R. [Innova Superconductor Technology Co., Ltd., 7 Rongchang Dongjie, Longsheng Industrial Park, Beijing Economic and Technological Developemnt Area, Beijing 100176 (China); Chen, H. [Department of Physics, Tsinghua University, Beijing 100084 (China); Shi, K., E-mail: shikai@tsinghua.edu.c [Department of Physics, Tsinghua University, Beijing 100084 (China); Wang, Z. [Department of Physics, School of Science, Beijing Institute of Technology, Beijing 100081 (China); Wu, W.; Han, Z. [Department of Physics, Tsinghua University, Beijing 100084 (China)

    2009-10-15

    In this work, an Ion Beam Assisted Deposition (IBAD) system was utilized to fabricate Yttria-Stabilized Zirconia (YSZ) template films for coated conductors. The surface of the Hastelloy C276 substrate was modified by rolling and electropolishing. The effect of the electropolishing parameters of the substrate on the texture of the YSZ buffer layers was studied. The electropolishing current and time were optimized for short samples of 1 cmx1 cm square shape as 1 A and 60 s, respectively. And the relationship between the roughness of the substrate surface and the texture of the YSZ layer is discussed. Reel-to-reel metal tape moving apparatus was installed and used to produce meter-long buffer layer for coated conductors. The YSZ template film was deposited by IBAD method on meter-long Hastelloy tape with tape shifting speed of 15-20 m/h, and the thickness of the buffer layer was up to about 1.7 mum. The Hastelloy substrate surface was measured by Atomic Force Microscope. The thickness of the YSZ films over length was measured by Thermal Field Emission Scan Electronic Microscopy. X Ray Diffraction OMEGA-scan and phi-scan measurements were performed in order to examine the out-of-plane and in-plane texture of the YSZ buffer layers, respectively.

  18. Fabrication of STO buffer films on MgO substrates by the MOD method

    International Nuclear Information System (INIS)

    We fabricated SrTiO3 (STO) thin films, which are expected to be used as buffer layers on MgO substrates, by the metal-organic decomposition (MOD) method, and evaluated the properties of the films. By introducing a 2-step heat treatment and optimizing the precursor temperature, we could improve the full width at half maximum (FWHM) values of the rocking curves up to 1.81 deg in the X-ray diffraction (XRD) measurements of the STO films on MgO substrates. The minimum FWMH value of the in-plane rocking curves of the films was 2.60 deg and the films had a cube-on-cube structure on the MgO substrates. Furthermore, the root mean square (rms) roughness values of the surfaces of the STO thin films derived from atomic force microscopy (AFM) were 2.11-5.37 nm

  19. Growth of b-axis oriented VO2 thin films on glass substrates using ZnO buffer layer

    International Nuclear Information System (INIS)

    VO2 thin films are grown on glass substrates by pulsed laser deposition using vanadium metal as a target. In this study, a ZnO thin film was used as a buffer layer for the growth of VO2 thin films on glass substrates. X-ray diffraction studies showed that the VO2 thin film had b-axis preferential orientation on a c-axis oriented ZnO buffer layer. The thickness of the ZnO buffer layer and the oxygen pressure during VO2 deposition were optimized to grow highly b-axis oriented VO2 thin films. The metal-insulator transition properties of the VO2 film samples were investigated in terms of infrared reflectance and electrical resistance with varying temperatures.

  20. INVESTIGATION ON THE MORPHOLOGY OF PRECIPITATED CHEMICALS FROM TE BUFFER ON SOLID SUBSTRATES

    OpenAIRE

    HUABIN WANG; LIJUAN ZHANG; FENG ZHANG; HONGJIE AN; SHIMOU CHEN; HAI LI; PENG WANG; XINYANG WANG; YANG WANG; HAIJUN YANG

    2007-01-01

    Buffer is often involved in the biological studies on a surface with the scanning probe microscopy and the remnant of the salts of buffer may affect the correct interpretation of the experimental results. However, the knowledge on the performance of chemicals of buffer on a substrate is still very poor. TE solution (Tris–HCl, NaCl, and ethylene diamine tetraacetic acid (EDTA)) is a widely used buffer in stocking biological molecules. Herein, we report the performance of the precipitated chemi...

  1. Influence of AlGaN Buffer Growth Temperature on GaN Epilayer based on Si(lll) Substrate

    International Nuclear Information System (INIS)

    This paper investigated the influence of AlGaN buffer growth temperature on strain status and crystal quality of the GaN film on Si(111) sbustrates by metal organic chemical vapor deposition. It was demonstrated by the optical microscopy that AlGaN buffer gorwth temperature had a remarkable effect on compensating tensil stress in top GaN layer and preventing the formation of cracks. X-ray diffraction and atomic force microscopy analysis showed crystal quality and surface morphology of the GaN epilayer could be improved through increasing AlGaN buffer growth temperature. 1μm crack-free GaN epilayer on Si (111) substrates was obtained with graded AlGaN buffer layer at optimized temperature of 1050 deg. C. Transmission electron microscopy analysis revealed that a significant reduction in threading dislocations was achieved in GaN epilayer.

  2. Influence of AlGaN Buffer Growth Temperature on GaN Epilayer based on Si(lll) Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wei Meng; Wang Xiaoliang; Pan Xu; Xiao Hongling; Wang Cuimei; Zhang Minglan [Materials Science Center, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083 (China); Wang Zhanguo, E-mail: mengw@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083 (China)

    2011-02-01

    This paper investigated the influence of AlGaN buffer growth temperature on strain status and crystal quality of the GaN film on Si(111) sbustrates by metal organic chemical vapor deposition. It was demonstrated by the optical microscopy that AlGaN buffer gorwth temperature had a remarkable effect on compensating tensil stress in top GaN layer and preventing the formation of cracks. X-ray diffraction and atomic force microscopy analysis showed crystal quality and surface morphology of the GaN epilayer could be improved through increasing AlGaN buffer growth temperature. 1{mu}m crack-free GaN epilayer on Si (111) substrates was obtained with graded AlGaN buffer layer at optimized temperature of 1050 deg. C. Transmission electron microscopy analysis revealed that a significant reduction in threading dislocations was achieved in GaN epilayer.

  3. Carbon Nanotube Patterning on a Metal Substrate

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor)

    2016-01-01

    A CNT electron source, a method of manufacturing a CNT electron source, and a solar cell utilizing a CNT patterned sculptured substrate are disclosed. Embodiments utilize a metal substrate which enables CNTs to be grown directly from the substrate. An inhibitor may be applied to the metal substrate to inhibit growth of CNTs from the metal substrate. The inhibitor may be precisely applied to the metal substrate in any pattern, thereby enabling the positioning of the CNT groupings to be more precisely controlled. The surface roughness of the metal substrate may be varied to control the density of the CNTs within each CNT grouping. Further, an absorber layer and an acceptor layer may be applied to the CNT electron source to form a solar cell, where a voltage potential may be generated between the acceptor layer and the metal substrate in response to sunlight exposure.

  4. Pulsed laser deposition of YBCO films on ISD MgO buffered metal tapes

    CERN Document Server

    Ma, B; Koritala, R E; Fisher, B L; Markowitz, A R; Erck, R A; Baurceanu, R; Dorris, S E; Miller, D J; Balachandran, U

    2003-01-01

    Biaxially textured magnesium oxide (MgO) films deposited by inclined-substrate deposition (ISD) are desirable for rapid production of high-quality template layers for YBCO-coated conductors. High-quality YBCO films were grown on ISD MgO buffered metallic substrates by pulsed laser deposition (PLD). Columnar grains with a roof-tile surface structure were observed in the ISD MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD MgO films are tilted at an angle from the substrate normal. A small full-width at half maximum (FWHM) of approx 9deg was observed in the phi-scan for ISD MgO films deposited at an inclination angle of 55deg . In-plane texture in the ISD MgO films developed in the first approx 0.5 mu m from the substrate surface, and then stabilized with further increases in film thickness. Yttria-stabilized zirconia and ceria buffer layers were deposited on the ISD MgO grown on metallic substrates prior to the deposition of YBCO by PLD. YBCO films with the c-axis parallel to the...

  5. GaN Epitaxial Layer Grown with Conductive Al(x)Ga(1-x)N Buffer Layer on SiC Substrate Using Metal Organic Chemical Vapor Deposition.

    Science.gov (United States)

    So, Byeongchan; Lee, Kyungbae; Lee, Kyungjae; Heo, Cheon; Pyeon, Jaedo; Ko, Kwangse; Jang, Jongjin; Nam, Okhyun

    2016-05-01

    This study investigated GaN epitaxial layer growth with a conductive Al(x)Ga(1-x)N buffer layer on n-type 4H-SiC by high-temperature metalorganic chemical vapor deposition (HT-MOCVD). The Al composition of the Al(x)Ga(1-x)N buffer was varied from 0% to 100%. In terms of the crystal quality of the GaN layer, 79% Al was the optimal composition of the Al(x)Ga(1-x)N buffer layer in our experiment. A vertical conductive structure was fabricated to measure the current voltage (I-V) characteristics as a function of Al composition, and the I-V curves showed that the resistance increased with increasing Al concentration of the Al(x)Ga(1-x)N buffer layer. PMID:27483845

  6. Investigation on the Morphology of Precipitated Chemicals from te Buffer on Solid Substrates

    Science.gov (United States)

    Wang, Huabin; Zhang, Lijuan; Zhang, Feng; An, Hongjie; Chen, Shimou; Li, Hai; Wang, Peng; Wang, Xinyang; Wang, Yang; Yang, Haijun

    Buffer is often involved in the biological studies on a surface with the scanning probe microscopy and the remnant of the salts of buffer may affect the correct interpretation of the experimental results. However, the knowledge on the performance of chemicals of buffer on a substrate is still very poor. TE solution (Tris-HCl, NaCl, and ethylene diamine tetraacetic acid (EDTA)) is a widely used buffer in stocking biological molecules. Herein, we report the performance of the precipitated chemicals from TE solution on two typical substrates with several commonly used sample preparation methods. The results showed that the chemicals in TE solution could self-organize into parallel nanofilaments on hydrophobic highly oriented pyrolitic graphite (HOPG) surface by blotting the shortly incubated solution droplet from the substrate or by drying the diluted solution droplet naturally. In contrast, no such special structures were observed on hydrophilic mica using the same methods. By imaging in TE solutions, no special structures were found on either the HOPG or the mica. Moreover, the effects of the concentration of chemicals of TE buffer on the morphology of precipitated chemicals were also investigated.

  7. Coincident site lattice-matched growth of semiconductors on substrates using compliant buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Norman, Andrew

    2016-08-23

    A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a silicon substrate using a compliant buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The compliant buffer material and semiconductor materials may be deposited using coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The coincident site lattice matching epitaxial process, as well as the use of a ductile buffer material, reduce the internal stresses and associated crystal defects within the deposited semiconductor materials fabricated using the disclosed method. As a result, the semiconductor devices provided herein possess enhanced performance characteristics due to a relatively low density of crystal defects.

  8. Pulsed laser deposition of YBCO films on ISD MgO buffered metal tapes

    International Nuclear Information System (INIS)

    Biaxially textured magnesium oxide (MgO) films deposited by inclined-substrate deposition (ISD) are desirable for rapid production of high-quality template layers for YBCO-coated conductors. High-quality YBCO films were grown on ISD MgO buffered metallic substrates by pulsed laser deposition (PLD). Columnar grains with a roof-tile surface structure were observed in the ISD MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD MgO films are tilted at an angle from the substrate normal. A small full-width at half maximum (FWHM) of ∼9deg was observed in the φ-scan for ISD MgO films deposited at an inclination angle of 55deg . In-plane texture in the ISD MgO films developed in the first ∼0.5 μm from the substrate surface, and then stabilized with further increases in film thickness. Yttria-stabilized zirconia and ceria buffer layers were deposited on the ISD MgO grown on metallic substrates prior to the deposition of YBCO by PLD. YBCO films with the c-axis parallel to the substrate normal have a unique orientation relationship with the ISD MgO films. An orientation relationship of YBCO(100)||MgO(111) and YBCO(010)||MgO(110) was measured by x-ray pole figure analyses and confirmed by transmission electron microscopy. A Tc of 91 K with a sharp transition and transport Jc of 5.5 x 105 A cm-2 at 77 K in self-field were measured on a YBCO film that was 0.46 μm thick, 4 mm wide and 10 mm long

  9. Adhesion enhancement of hard coatings deposited on flexible plastic substrates using an interfacial buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Day-Shan; Wu, Cheng-Yang, E-mail: dsliu@sunws.nfu.edu.t [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei, Taiwan 63201 (China)

    2010-05-05

    An interfacial buffer layer has been developed to improve the silicon oxide (SiO{sub x}) hard coating adhered to a flexible plastic substrate through a consecutive plasma-enhanced chemical vapour deposition process, using the same organosilicon precursor. The adhesion of the hard coating structure, correlated with the buffer layer thickness, was rated by the standard tape-peeling test. An excellent adhesion (rank 5B) was available for the hard coating structure with an interfacial buffer layer deposited on polycarbonate and polymethylmethacrylate substrates. The degree of adhesion strength for the hard coating structures was measured by the standard scratch test. The increase in the critical loads determined from the scratch test was well correlated with the tape-peeling test results. The hard coating structure showed excellent adhesion and also corresponded to a minimum residual stress. The mechanisms responsible for the adhesion enhancement were linked to the specific chemical bonds of the hydrocarbon C-H bond, and cross-linking Si-C bond appeared in the interfacial buffer layer. The C-H bond was recognized as a hydrophobic group that was favourable for minimizing the adsorption of ambient contaminants potentially arising during deposition, while the cross-linking Si-C bond functioned to compensate the large tensile stress residing in the SiO{sub x} hard coating. As a consequence, a close contact and progressive morphology resulting in excellent adhesion were observed at the interface of the hard coating structure with an interfacial buffer layer.

  10. Methods of selectively incorporating metals onto substrates

    Science.gov (United States)

    Ernst; Richard D. , Eyring; Edward M. , Turpin; Gregory C. , Dunn; Brian C.

    2008-09-30

    A method for forming multi-metallic sites on a substrate is disclosed and described. A substrate including active groups such as hydroxyl can be reacted with a pretarget metal complex. The target metal attached to the active group can then be reacted with a secondary metal complex such that an oxidation-reduction (redox) reaction occurs to form a multi-metallic species. The substrate can be a highly porous material such as aerogels, xerogels, zeolites, and similar materials. Additional metal complexes can be reacted to increase catalyst loading or control co-catalyst content. The resulting compounds can be oxidized to form oxides or reduced to form metals in the ground state which are suitable for practical use.

  11. Deposition of CeO 2/YSZ buffer layer on Hastelloy substrates for MOD process of YBa 2Cu 3O 7- x film

    Science.gov (United States)

    Fuji, Hiroshi; Honjo, Tetsuji; Nakamura, Yuichi; Izumi, Teruo; Takeshi, Araki; Hirabayashi, Izumi; Shiohara, Yuh; Iijima, Yasuhiro; Takeda, Kaoru

    2001-08-01

    Trifluoroacetate metalorganic deposition (TFA-MOD) process is expected as a low cost process for mass production of coated conductors because it is a non-vacuum process. In order to apply the technique to fabrication of coated conductors, suitable buffer layers have to be considered to achieve a high orientation of superconducting layer and prevention of the reaction with metal substrate. The combination of CeO 2 on IBAD-YSZ is considered as an effective buffer for TFA-MOD process expecting to satisfy a high acid resistivity and high crystal grain alignment. The CeO 2 buffer layer was deposited on IBAD-YSZ/Hastelloy substrates by RF magnetron sputtering. From XRD analysis, the CeO 2 buffer layer showed very good in-plane alignment on YSZ-IBAD buffer layer. In a holding time of 1 h, the suitable maximum heat treatment temperature was found to be from 750°C to 775°C for TFA-Y123 on metal substrate. The Jc- B property of Y123 on CeO 2/YSZ/Hastelloy shows the Jc values of 1.4 MA/cm 2 at 77.3 K, 0 T and more than 10 5 A/cm 2 at 77.3 K, 2 T. The high performance under high magnetic field was confirmed.

  12. Thick lanthanum zirconate buffer layers from water-based precursor solutions on Ni-5%W substrates

    International Nuclear Information System (INIS)

    In this work, water-based precursor solutions suitable for dip-coating of thick La2Zr2O7 (LZO) buffer layers for coated conductors on Ni-5%W substrates were developed. The solutions were prepared based on chelate chemistry using water as the main solvent. The effect of polymer addition on the maximum crack-free thickness of the deposited films was investigated. This novel solution preparation method revealed the possibility to grow single, crack-free layers with thicknesses ranging 100-280 nm with good crystallinity and an in-plane grain misalignment with average FWHM of 6.55o. TEM studies illustrated the presence of nanovoids, typical for CSD-LZO films annealed under Ar-5%H2 gas flow. The appropriate buffer layer action of the film in preventing the Ni diffusion was studied using XPS. It was found that the Ni diffusion was restricted to the first 30 nm of a 140 nm thick film. The surface texture of the film was improved using a seed layer. - Graphical abstract: Thick LZO buffer layers from water-based precursor solutions were synthesized and their crystallinity, microstructure and buffer layer action were studied. The buffer layer action of the LZO layer was substantial to restrict the Ni penetration within 30 nm of a 140 nm thick film. Highlights: → LZO buffer layers with high thicknesses for use in coated conductors were prepared. → Prepared from water-based solutions. → Polymeric PVP increases the crack-free critical thickness of thick films. → Thick films showed good barrier action against Ni penetration. → Seed layers promote epitaxial growth of thick layers.

  13. Hydrogen production in microbial reverse-electrodialysis electrolysis cells using a substrate without buffer solution.

    Science.gov (United States)

    Song, Young-Hyun; Hidayat, Syarif; Kim, Han-Ki; Park, Joo-Yang

    2016-06-01

    The aim of this work was to use substrate without buffer solution in a microbial reverse-electrodialysis electrolysis cell (MREC) for hydrogen production under continuous flow condition (10 cell pairs of RED stacks, HRT=5, 7.5, and 15h). Decreasing in the HRT (increasing in the organic matter) made cell current stable and increased. Hydrogen gas was produced at a rate of 0.61m(3)-H2/m(3)-Van/d in H-MREC, with a COD removal efficiency of 81% (1.55g/L/d) and a Coulombic efficiency of 41%. This MREC system without buffer solution could successfully produce hydrogen gas at a consistent rate. PMID:26888336

  14. YBa2Cu3O7-x films on flexible, partially stabilized zirconia substrates with fully stabilized zirconia buffer layers

    International Nuclear Information System (INIS)

    Textured polycrystalline YBCO films with superconducting transition temperatures of ∼90 K have been prepared on flexible zirconia substrates, partially stabilized by 3 mol % yttria. X-ray data suggest undesirable (013) and [(110) (103)] texture in minor amounts within the predominantly c-axis oriented film. The transmission electron microscope data reveal clean, special crystallographic as well as silicon contaminated grain boundaries containing amorphous phases. By depositing a zirconia buffer layer, fully stabilized by 9 mol % yttria, we have demonstrated that the normal-state metallic and superconducting properties of the YBCO films can be considerably improved. These films exhibit critical-current densities of ∼0.9x104 A/cm2 at 77 K in zero field and 2x105 A/cm2 at 4.2 K in zero field

  15. The effect of the carbon nanotube buffer layer on the performance of a Li metal battery

    Science.gov (United States)

    Zhang, Ding; Zhou, Yi; Liu, Changhong; Fan, Shoushan

    2016-05-01

    Lithium (Li) metal is one of the most promising candidates as an anode for the next-generation energy storage systems because of its high specific capacity and lowest negative electrochemical potential. But the growth of Li dendrites limits the application of the Li metal battery. In this work, a type of modified Li metal battery with a carbon nanotube (CNT) buffer layer inserted between the separator and the Li metal electrode was reported. The electrochemical results show that the modified batteries have a much better rate capability and cycling performance than the conventional Li metal batteries. The mechanism study by electrochemical impedance spectroscopy reveals that the modified battery has a smaller charge transfer resistance and larger Li ion diffusion coefficient during the deposition process on the Li electrode than the conventional Li metal batteries. Symmetric battery tests show that the interfacial behavior of the Li metal electrode with the buffer layer is more stable than the naked Li metal electrode. The morphological characterization of the CNT buffer layer and Li metal lamina reveals that the CNT buffer layer has restrained the growth of Li dendrites. The CNT buffer layer has great potential to solve the safety problem of the Li metal battery.Lithium (Li) metal is one of the most promising candidates as an anode for the next-generation energy storage systems because of its high specific capacity and lowest negative electrochemical potential. But the growth of Li dendrites limits the application of the Li metal battery. In this work, a type of modified Li metal battery with a carbon nanotube (CNT) buffer layer inserted between the separator and the Li metal electrode was reported. The electrochemical results show that the modified batteries have a much better rate capability and cycling performance than the conventional Li metal batteries. The mechanism study by electrochemical impedance spectroscopy reveals that the modified battery has a

  16. Fractal analysis and atomic force microscopy measurements of surface roughness for Hastelloy C276 substrates and amorphous alumina buffer layers in coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Feng, F.; Shi, K.; Xiao, S.-Z.; Zhang, Y.-Y. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Zhao, Z.-J. [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Wang, Z., E-mail: wangzhi@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Wei, J.-J.; Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)

    2012-02-01

    In coated conductors, surface roughness of metallic substrates and buffer layers could significantly affect the texture of subsequently deposited buffer layers and the critical current density of superconductor layer. Atomic force microscopy (AFM) is usually utilized to measure surface roughness. However, the roughness values are actually relevant to scan scale. Fractal geometry could be exerted to analyze the scaling performance of surface roughness. In this study, four samples were prepared, which were electro polished Hastelloy C276 substrate, mechanically polished Hastelloy C276 substrate and the amorphous alumina buffer layers deposited on both the substrates by ion beam deposition. The surface roughness, described by root mean squared (RMS) and arithmetic average (R{sub a}) values, was analyzed considering the scan scale of AFM measurements. The surfaces of amorphous alumina layers were found to be fractal in nature because of the scaling performance of roughness, while the surfaces of Hastelloy substrates were not. The flatten modification of AFM images was discussed. And the calculation of surface roughness in smaller parts divided from the whole AFM images was studied, compared with the results of actual AFM measurements of the same scan scales.

  17. Fractal analysis and atomic force microscopy measurements of surface roughness for Hastelloy C276 substrates and amorphous alumina buffer layers in coated conductors

    Science.gov (United States)

    Feng, F.; Shi, K.; Xiao, S.-Z.; Zhang, Y.-Y.; Zhao, Z.-J.; Wang, Z.; Wei, J.-J.; Han, Z.

    2012-02-01

    In coated conductors, surface roughness of metallic substrates and buffer layers could significantly affect the texture of subsequently deposited buffer layers and the critical current density of superconductor layer. Atomic force microscopy (AFM) is usually utilized to measure surface roughness. However, the roughness values are actually relevant to scan scale. Fractal geometry could be exerted to analyze the scaling performance of surface roughness. In this study, four samples were prepared, which were electro polished Hastelloy C276 substrate, mechanically polished Hastelloy C276 substrate and the amorphous alumina buffer layers deposited on both the substrates by ion beam deposition. The surface roughness, described by root mean squared (RMS) and arithmetic average (Ra) values, was analyzed considering the scan scale of AFM measurements. The surfaces of amorphous alumina layers were found to be fractal in nature because of the scaling performance of roughness, while the surfaces of Hastelloy substrates were not. The flatten modification of AFM images was discussed. And the calculation of surface roughness in smaller parts divided from the whole AFM images was studied, compared with the results of actual AFM measurements of the same scan scales.

  18. Fractal analysis and atomic force microscopy measurements of surface roughness for Hastelloy C276 substrates and amorphous alumina buffer layers in coated conductors

    International Nuclear Information System (INIS)

    In coated conductors, surface roughness of metallic substrates and buffer layers could significantly affect the texture of subsequently deposited buffer layers and the critical current density of superconductor layer. Atomic force microscopy (AFM) is usually utilized to measure surface roughness. However, the roughness values are actually relevant to scan scale. Fractal geometry could be exerted to analyze the scaling performance of surface roughness. In this study, four samples were prepared, which were electro polished Hastelloy C276 substrate, mechanically polished Hastelloy C276 substrate and the amorphous alumina buffer layers deposited on both the substrates by ion beam deposition. The surface roughness, described by root mean squared (RMS) and arithmetic average (Ra) values, was analyzed considering the scan scale of AFM measurements. The surfaces of amorphous alumina layers were found to be fractal in nature because of the scaling performance of roughness, while the surfaces of Hastelloy substrates were not. The flatten modification of AFM images was discussed. And the calculation of surface roughness in smaller parts divided from the whole AFM images was studied, compared with the results of actual AFM measurements of the same scan scales.

  19. The effect of the carbon nanotube buffer layer on the performance of a Li metal battery.

    Science.gov (United States)

    Zhang, Ding; Zhou, Yi; Liu, Changhong; Fan, Shoushan

    2016-06-01

    Lithium (Li) metal is one of the most promising candidates as an anode for the next-generation energy storage systems because of its high specific capacity and lowest negative electrochemical potential. But the growth of Li dendrites limits the application of the Li metal battery. In this work, a type of modified Li metal battery with a carbon nanotube (CNT) buffer layer inserted between the separator and the Li metal electrode was reported. The electrochemical results show that the modified batteries have a much better rate capability and cycling performance than the conventional Li metal batteries. The mechanism study by electrochemical impedance spectroscopy reveals that the modified battery has a smaller charge transfer resistance and larger Li ion diffusion coefficient during the deposition process on the Li electrode than the conventional Li metal batteries. Symmetric battery tests show that the interfacial behavior of the Li metal electrode with the buffer layer is more stable than the naked Li metal electrode. The morphological characterization of the CNT buffer layer and Li metal lamina reveals that the CNT buffer layer has restrained the growth of Li dendrites. The CNT buffer layer has great potential to solve the safety problem of the Li metal battery. PMID:27181758

  20. Graphene on a metal surface with an h-BN buffer layer: gap opening and N-doping

    Science.gov (United States)

    Wang, Tao; Lu, Yunhao; Feng, Y. P.

    2016-04-01

    Graphene grown on a metal surface, Cu(111), with a boron-nitride (h-BN) buffer layer is studied. Our first-principles calculations reveal that charge is transferred from the copper substrate to graphene through the h-BN buffer layer which results in n-doped graphene in the absence of a gate voltage. More importantly, a gap of 0.2 eV, which is comparable to that of a typical narrow gap semiconductor, opens just 0.5 eV below the Fermi level at the Dirac point. The Fermi level can be easily shifted inside this gap to make graphene a semiconductor, which is crucial for graphene-based electronic devices. A graphene-based p-n junction can be realized with graphene eptaxially grown on a metal surface.

  1. Influence of electrode, buffer gas and control gear on metal halide lamp performance

    International Nuclear Information System (INIS)

    In this paper the influence of electrode composition, buffer gas fill pressure and control gear on the performance of metal halide lamps is investigated. It is shown that pure tungsten electrodes improve lumen maintenance and reduce voltage rise over lamp life. An optimum buffer gas fill pressure condition is discovered which allows for reduced electrode erosion during lamp starting as well as under normal operating conditions. Use of electronic control gear is shown to improve the performance of metal halide lamps

  2. Light Confinement by a Cylindric Metallic Waveguide in Dense Buffer Gas Environment

    CERN Document Server

    Vogl, Ulrich; Vewinger, Frank; Weitz, Martin; Solovev, Alexander; Mei, Yongfeng; Schmidt, Oliver

    2010-01-01

    We report on the implementation of metallic microtubes in a system of rubidium vapour at 230\\,bar of argon buffer gas. The high buffer gas pressure leads to a widely pressure broadened linewidth of several nanometers, interpolating between the sharp atomic physics spectra and the band structure of solid state systems. Tube-like metallic waveguide structures have been inserted in the high pressure buffer gas system, allowing for an enhancement of the atom-light interaction over an optical guiding length in the tube of up to 1\\,mm. The system holds promise for nonlinear optics experiments and the study of atom-light polariton condensation.

  3. Growth of YBCO film on SrRuO3-buffered MgO substrate

    International Nuclear Information System (INIS)

    The superconducting, crystalline, and morphological properties of YBCO films deposited on SrRuO3-buffered MgO substrates were studied at various deposition temperatures. The film deposited at T = 770 deg. C had the best superconducting properties (critical current density of 2.5 x 106 A cm-2 and critical transition temperature of 91 K). Scanning electron micrographs of this film revealed uniform and well-connected grains. X-ray analyses revealed that the Y BCO/SrRuO3/MgO film fabricated at 770 deg. C had good in-plane and out-of-plane textures. Raman spectroscopy showed that this film had the best out-of-plane texture and orthorhombic I domains

  4. Biaxially oriented CdTe films on glass substrate through nanostructured Ge/CaF2 buffer layers

    Science.gov (United States)

    Lord, R. J.; Su, P.-Y.; Bhat, I.; Zhang, S. B.; Lu, T.-M.; Wang, G.-C.

    2015-09-01

    Heteroepitaxial CdTe films were grown by metal organic chemical vapor deposition on glass substrates through nanostructured Ge/CaF2 buffer layers which were biaxially oriented. It allows us to explore the structural properties of multilayer biaxial semiconductor films which possess small angle grain boundaries and to test the principle of a solar cell made of such low-cost, low-growth-temperature semiconductor films. Through the x-ray diffraction and x-ray pole figure analysis, the heteroepitaxial relationships of the mutilayered films are determined as [111] in the out-of-plane direction and CdTe//Ge//{ }{{{CaF}}2} in the in-plane direction. The I-V curves measured from an ITO/CdS/CdTe/Ge/CaF2/glass solar cell test structure shows a power conversion efficiency of ˜η = 1.26%, illustrating the initial success of such an approach. The observed non-ideal efficiency is believed to be due to a low shunt resistance and high series resistance as well as some residual large-angle grain boundary effects, leaving room for significant further improvement.

  5. TiN-buffered substrates for photoelectrochemical measurements of oxynitride thin films

    Science.gov (United States)

    Pichler, Markus; Pergolesi, Daniele; Landsmann, Steve; Chawla, Vipin; Michler, Johann; Döbeli, Max; Wokaun, Alexander; Lippert, Thomas

    2016-04-01

    Developing novel materials for the conversion of solar to chemical energy is becoming an increasingly important endeavour. Perovskite compounds based on bandgap tunable oxynitrides represent an exciting class of novel photoactive materials. To date, literature mostly focuses on the characterization of oxynitride powder samples which have undeniable technological interest but do not allow the investigation of fundamental properties such as the role of the crystalline quality and/or the surface crystallographic orientation toward photo-catalytic activity. The challenge of growing high quality oxynitride thin films arises from the availability of a suitable substrate, owing to strict material and processing requirements: effective lattice matching, sufficiently high conductivities, stability under high temperatures and in strongly reducing environments. Here, we have established the foundations of a model system incorporating a TiN-buffer layer which enables fundamental investigations into crystallographic surface orientation and crystalline quality of the photocatalyst against photo(electro)chemical performance to be effectively performed. Furthermore, we find that TiN as current collector enables control over the nitrogen content of oxynitride thin films produced by a modified pulsed laser deposition method and allows the growth of highly ordered LaTiO3-xNx thin films.

  6. Effects of Si doping on the strain relaxation of metamorphic (Al)GaInP buffers grown on GaAs substrates

    Energy Technology Data Exchange (ETDEWEB)

    Li, K.L. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123, People’ s Republic of China (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Dong, J.R., E-mail: jrdong2007@sinano.ac.cn [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123, People’ s Republic of China (China); Sun, Y.R.; Zeng, X.L. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123, People’ s Republic of China (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Y.M.; Yu, S.Z.; Zhao, C.Y.; Yang, H. [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123, People’ s Republic of China (China)

    2014-01-01

    We investigate the effects of Si doping on the strain relaxation of the compositionally step-graded (Al)GaInP buffers grown by metal-organic chemical vapor deposition on (0 0 1) GaAs substrates with different miscuts toward (1 1 1)A. It is found that in the 2° samples, high Si doping can reduce both the α and β dislocation densities by delaying and suppressing the formation of phase separation in the buffer. In contrast, in the 7° samples, Si dopants deteriorate the buffer quality through increasing the dislocation density accompanying with the tilt reduction along the [1 1 0] direction, and a striking feature, bunches of β dislocations away from the interfaces, is observed in the [1 1 0] cross-sectional transmission electron microscopy images. A cross-slip mechanism closely associated with the pinning effect of Si on α dislocation motion is proposed to explain the multiplication of β dislocations. These results indicate that selecting a moderate Si doping density and substrate miscut are critical for the design and fabrication of metamorphic optoelectronic devices.

  7. Effects of Si doping on the strain relaxation of metamorphic (Al)GaInP buffers grown on GaAs substrates

    International Nuclear Information System (INIS)

    We investigate the effects of Si doping on the strain relaxation of the compositionally step-graded (Al)GaInP buffers grown by metal-organic chemical vapor deposition on (0 0 1) GaAs substrates with different miscuts toward (1 1 1)A. It is found that in the 2° samples, high Si doping can reduce both the α and β dislocation densities by delaying and suppressing the formation of phase separation in the buffer. In contrast, in the 7° samples, Si dopants deteriorate the buffer quality through increasing the dislocation density accompanying with the tilt reduction along the [1 1 0] direction, and a striking feature, bunches of β dislocations away from the interfaces, is observed in the [1 1 0] cross-sectional transmission electron microscopy images. A cross-slip mechanism closely associated with the pinning effect of Si on α dislocation motion is proposed to explain the multiplication of β dislocations. These results indicate that selecting a moderate Si doping density and substrate miscut are critical for the design and fabrication of metamorphic optoelectronic devices.

  8. A possibility of enhancing Jc in MgB2 film grown on metallic hastelloy tape with the use of SiC buffer layer

    International Nuclear Information System (INIS)

    We have grown MgB2 on SiC buffer layer by using metallic Hastelloy tape as the substrate. Hastelloy tape was chosen for its potential practical applications, mainly in the power cable industry. SiC buffer layers were deposited on Hastelloy tapes at 400, 500, and 600 degrees C by using a pulsed laser deposition method, and then by using a hybrid physical-chemical vapor deposition technique, MgB2 films were grown on the three different SiC buffer layers. An enhancement of critical current density values were noticed in the MgB2 films on SiC/Hastelloy deposited at 500 and 600 degrees C. From the surface analysis, smaller and denser grains of MgB2 tapes are likely to cause this enhancement. This result infers that the addition of SiC buffer layers may contribute to the improvement of superconducting properties of MgB2 tapes.

  9. Impact of buffer growth on crystalline quality of GaN grown on Si(111) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Drechsel, Philipp [OSRAM Opto Semiconductors GmbH, Regensburg (Germany); Paul-Drude Institute for Solid-State Electronics, Berlin (Germany); Stauss, Peter; Bergbauer, Werner; Rode, Patrick; Steegmueller, Ulrich [OSRAM Opto Semiconductors GmbH, Regensburg (Germany); Fritze, Stephanie; Krost, Alois [Otto-von-Guericke University of Magdeburg (Germany); Markurt, Toni; Schulz, Tobias; Albrecht, Martin [Leibniz Institute for Crystal Growth, Berlin (Germany); Riechert, Henning [Paul-Drude Institute for Solid-State Electronics, Berlin (Germany)

    2012-03-15

    In this work we focus on the impact of different buffer and nucleation layers on the corresponding crystalline quality of gallium nitride (GaN), grown by metal-organic chemical vapour deposition (MOCVD). In situ curvature measurements, X-ray diffraction (XRD) and transmission electron microscopy (TEM) are used for advanced characterization. The influence of various growth modes on meltback etching and cracking is analyzed. Also the effect of a silicon nitride (SiN) mask on the growth of GaN and its coalescence is investigated. Furthermore, associated potential consequences for the growth of aluminium nitride (AlN) interlayers are examined to obtain a homogeneous surface without cracks and with good crystalline quality. Our studies indicate that an incomplete coalesced GaN surface located underneath the AlN interlayer leads to an increased defect density. Additionally we studied the influence of growth temperature at nucleation on the material quality and the process stability. Finally we demonstrate interlayer induced compressive strain during GaN growth with an XRD rocking-curve full width half maximum (FWHM) as low as 450 arc seconds for the 10 anti 12 reflection. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Ligand-enhanced electrokinetic remediation of metal-contaminated marine sediments with high acid buffering capacity.

    Science.gov (United States)

    Masi, Matteo; Iannelli, Renato; Losito, Gabriella

    2016-06-01

    The suitability of electrokinetic remediation for removing heavy metals from dredged marine sediments with high acid buffering capacity was investigated. Laboratory-scale electrokinetic remediation experiments were carried out by applying two different voltage gradients to the sediment (0.5 and 0.8 V/cm) while circulating water or two different chelating agents at the electrode compartments. Tap water, 0.1 M citric acid and 0.1 M ethylenediaminetetraacetic acid (EDTA) solutions were used respectively. The investigated metals were Zn, Pb, V, Ni and Cu. In the unenhanced experiment, the acid front could not propagate due to the high acid buffering capacity of the sediments; the production of OH(-) ions at the cathode resulted in a high-pH environment causing the precipitation of CaCO3 and metal hydroxides. The use of citric acid prevented the formation of precipitates, but solubilisation and mobilisation of metal species were not sufficiently achieved. Metal removal was relevant when EDTA was used as the conditioning agent, and the electric potential was raised up to 0.8 V/cm. EDTA led to the formation of negatively charged complexes with metals which migrated towards the anode compartment by electromigration. This result shows that metal removal from sediments with high acid buffering capacity may be achieved by enhancing the electrokinetic process by EDTA addition when the acidification of the medium is not economically and/or environmentally sustainable. PMID:26490900

  11. Effects of parylene buffer layer on flexible substrate in organic light emitting diode

    International Nuclear Information System (INIS)

    Parylene was deposited on a bare polyethylene terephthalate (PET) and poly carbonate (PC) film surface to enhance the oxygen and water barrier properties at room temperature. The deposition rate of the parylene was observed to have increased linearly as the working pressure was increased. The oxygen plasma pre-treatment of the PET for the adhesion between bare film and parylene was mostly effective to 5B, while the treatment of N-(2-Aminoethyl)-3-Aminopropylmethyldimethoxysilane solution at PC film resulted in 3B. Surface morphology and roughness were observed by atomic force microscopy and the barrier property was measured by oxygen transmission rate and water vapor permeation test equipments. The oxygen transmission rate (OTR) and water vapor transmission rate (WTR) of the PET film were reduced from 13.2 to 11.3 cc/m2 day and from 4.6 to 2.0 g/m2 day, respectively. When the parylene layer was coated onto the PC film, however, the barrier effects were significant from out of detection limit to 53.9 cc/m2 day for the OTR, and from 24.7 to 3.5 g/m2 day for the WTR. The real organic light emitting diode (OLED) device was fabricated with a parylene coated flexible substrate, which was subsequently deposited by transparent conducting layer and scratch-resistant layer. The initial brightness of the OLED device with a parylene buffer layer was 173 cd/cm2, and 70% of its initial brightness was maintained after 40,000 s

  12. Investigations into alterntive substrate, absorber, and buffer layer processing for Cu(In,Ga)Se{sub 2}-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tuttle, J.R.; Berens, T.A.; Keane, J. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    High-performance Cu(In,Ga)Se{sub 2}(CIGS)-based solar cells are presently fabricated within a narrow range of processing options. In this contribution, alternative substrate, absorber, and buffer layer processing is considered. Cell performance varies considerably when alternative substrates are employed. These variations are narrowed with the addition of Na via a Na{sub 2}S compound. Sputtered and electrodeposited CIGS precursors and completed absorbers show promise as alternatives to evaporation. A recrystallization process is required to improve their quality. (In,Ga){sub y}Se buffer layers contribute to cell performance above 10. Further improvements in these alternatives will lead to combined cell performance greater than 10% in the near term.

  13. Palladium buffer-layered high performance ionic polymer–metal composites

    International Nuclear Information System (INIS)

    A new IPMC fabrication method—that is not a repetitive reduction processes—and a new supporting electrode material that is responsible for this procedure are described in this paper. A palladium metal, acting as a buffer layer, was deposited before plating the platinum electrode in order to articulate the surface morphology and the interfacial effect between the electrode and the membrane. The platinum layer was sequentially grown using an electroless chemical deposition on a palladium buffer layer on the polymer membrane. The surface morphology and conductivity of the electrode were enhanced by depositing a buffer layer. Under the same applied voltage, when compared to IPMCs without a buffer layer, the IPMCs with a palladium buffer layer showed a greater bending tendency and had a higher blocking force. The results also indicated that such IPMCs do not exhibit the back relaxation phenomenon under a sustained DC voltage. The amplitude of the transduction signal produced by the Pt/Pd IPMC shows much larger amplitude of the signal produced by the Pt IPMC. Thus, the IPMC with a palladium buffer layer has the potential for future applications as an actuator and transducer

  14. Study of High Quality Indium Nitride Films Grown on Si(100 Substrate by RF-MOMBE with GZO and AlN Buffer Layers

    Directory of Open Access Journals (Sweden)

    Wei-Chun Chen

    2012-01-01

    Full Text Available Wurtzite structure InN films were prepared on Si(100 substrates using radio-frequency metal-organic molecular beam epitaxy (RF-MOMBE system. Ga-doped ZnO (GZO and Amorphous AlN (a-AlN film were used as buffer layers for InN films growth. Structural, surface morphology and optical properties of InN films were investigated by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, and photoluminescence (PL. XRD results indicated that all InN films exhibited preferred growth orientation along the c-axis with different intermediate buffers. TEM images exhibit the InN/GZO growth by two-dimensional mode and thickness about 900 nm. Also, the InN films can be obtained by growth rate about ~1.8 μm/h. Optical properties indicated that the band gap of InN/GZO is about 0.79 eV. These results indicate that the control of buffer layer is essential for engineering the growth of InN on silicon wafer.

  15. Effect of noble metal buffer layers on superconducting YBa2Cu3O7 thin films

    International Nuclear Information System (INIS)

    Superconducting YBa2Cu3O7 thin films have been prepared by using a magnetron sputtering system in the single-source mode. Samples deposited on [100] single-crystal MgO with and without a Au buffer layer all show high transition temperatures (82--87 K). The use of a Au buffer layer significantly improves the superconducting properties, particularly the Meissner effect and critical current density (3.3 x 106 A/cm2 at T = 2 K and 3.5 x 104 A/cm2 at T = 77 K). The Au films remain metallic after high-temperature annealing in an oxygen atmosphere. We propose to use Au buffer layers as current shunts to protect superconducting films and devices

  16. The effects of buffer layers on the performance and stability of flexible InGaZnO thin film transistors on polyimide substrates

    Science.gov (United States)

    Ok, Kyung-Chul; Ko Park, Sang-Hee; Hwang, Chi-Sun; Kim, H.; Soo Shin, Hyun; Bae, Jonguk; Park, Jin-Seong

    2014-02-01

    We demonstrated the fabrication of flexible amorphous indium gallium zinc oxide thin-film transistors (TFTs) on high-temperature polyimide (PI) substrates, which were debonded from the carrier glass after TFT fabrication. The application of appropriate buffer layers on the PI substrates affected the TFT performance and stability. The adoption of the SiNx/AlOx buffer layers as water and hydrogen diffusion barriers significantly improved the device performance and stability against the thermal annealing and negative bias stress, compared to single SiNx or SiOx buffer layers. The substrates could be bent down to a radius of curvature of 15 mm and the devices remained normally functional.

  17. Epitaxial ZnO films grown on ZnO-buffered c-plane sapphire substrates by hydrothermal method

    International Nuclear Information System (INIS)

    ZnO films are hydrothermally grown on ZnO-buffered c-plane sapphire substrates at a low temperature of 70 deg. C. A radio-frequency (RF) reactive magnetron sputtering has been used to grow the ZnO buffer layers. X-ray diffraction, scanning electron microscopy, and room temperature photoluminescence are carried out to characterize the structure, morphology and optical property of the films. It is found that the films are stress-free. The epitaxial relationship between the ZnO film and the c-plane sapphire substrate is found to be ZnO (0 0 0 1)||Al2O3 (0 0 0 1) in the surface normal and ZnO[101-bar 0]||Al2O3[112-bar 0] in plane. Sapphire treatment, as such acid etching, nitridation, and oxidation are found to influence the nucleation of the film growth, and the buffer layers determine the crystalline quality of the ZnO films. The maximum PL quantum efficiency of ZnO films grown with hydrothermal method is found to be about 80% of single-crystal ZnO.

  18. Preparation of MgO Films as Buffer Layers by Laser-ablation at Various Substrate Temperatures

    Institute of Scientific and Technical Information of China (English)

    LI Ling; WANG Chuanbin; WANG Fang; SHEN Qiang; ZHANG Lianmeng

    2011-01-01

    MgO thin films were deposited on Si(100) substrates by laser ablation under various substrate temperatures (Tsub),expecting to provide a candidate buffer layer for the textured growth of functional perovskite oxide films on Si substrates.The effect of Tsub on the preferred orientation,crystallinity and surface morphology of the films was investigated.MgO films in single-phase were obtained at 473-973 K.With increasing Tsub,the preferred orientation of the films changed from (200) to (111).The crystallinity and surface morphology was different too,depending on Tsub·At Tsub=673 K,the MgO film became uniform and smooth,exhibiting high crystallinity and a dense texture.

  19. Control of threading dislocations by Al(Ga)InAs reverse-graded buffers grown on GaAs substrates

    Science.gov (United States)

    He, Yang; Sun, Yurun; Song, Yan; Zhao, Yongming; Yu, Shuzhen; Dong, Jianrong

    2016-06-01

    High-quality strain-relaxed InP layers with undulating step-graded Al(Ga)InAs buffers were grown on GaAs substrates by metal–organic chemical vapor deposition. Transmission electron microscopy, high-resolution electron microscopy (HREM), atom force microscopy, and photoluminescence were carried out to characterize the metamorphic buffers. V-shaped dislocations in [001] Al(Ga)InAs reverse-graded layers were observed by HREM and the behavior of reverse-graded layers was simulated theoretically using analytical models. Both the experimental and theoretical results indicated that the insertion of reverse-graded layers with appropriately designed thicknesses and In grading coefficients promotes the annihilation and coalescence reactions between threading dislocations and reduces threading dislocations density.

  20. The W-W02 Oxygen Fugacity Buffer at High Pressures and Temperatures: Implications for f02 Buffering and Metal-silicate Partitioning

    Science.gov (United States)

    Shofner, G. A.; Campbell, A. J.; Danielson, L.; Righter, K.

    2013-01-01

    Oxygen fugacity (fO2) controls multivalent phase equilibria and partitioning of redox-sensitive elements, and it is important to understand this thermodynamic parameter in experimental and natural systems. The coexistence of a metal and its oxide at equilibrium constitutes an oxygen buffer which can be used to control or calculate fO2 in high pressure experiments. Application of 1-bar buffers to high pressure conditions can lead to inaccuracies in fO2 calculations because of unconstrained pressure dependencies. Extending fO2 buffers to pressures and temperatures corresponding to the Earth's deep interior requires precise determinations of the difference in volume (Delta) V) between the buffer phases. Synchrotron x-ray diffraction data were obtained using diamond anvil cells (DAC) and a multi anvil press (MAP) to measure unit cell volumes of W and WO2 at pressures and temperatures up to 70 GPa and 2300 K. These data were fitted to Birch-Murnaghan 3rd-order thermal equations of state using a thermal pressure approach; parameters for W are KT = 306 GPa, KT' = 4.06, and aKT = 0.00417 GPa K-1. Two structural phase transitions were observed for WO2 at 4 and 32 GPa with structures in P21/c, Pnma and C2/c space groups. Equations of state were fitted for these phases over their respective pressure ranges yielding the parameters KT = 190, 213, 300 GPa, KT' = 4.24, 5.17, 4 (fixed), and aKT = 0.00506, 0.00419, 0.00467 GPa K-1 for the P21/c, Pnma and C2/c phases, respectively. The W-WO2 buffer (WWO) was extended to high pressure by inverting the W and WO2 equations of state to obtain phase volumes at discrete pressures (1-bar to 100 GPa, 1 GPa increments) along isotherms (300 to 3000K, 100 K increments). The slope of the absolute fO2 of the WWO buffer is positive with increasing temperature up to approximately 70 GPa and is negative above this pressure. The slope is positive along isotherms from 1000 to 3000K with increasing pressure up to at least 100 GPa. The WWO buffer is at

  1. Catalyst-free growth of InP nanowires on patterned Si (001) substrate by using GaAs buffer layer

    Science.gov (United States)

    Li, Shiyan; Zhou, Xuliang; Kong, Xiangting; Li, Mengke; Mi, Junping; Pan, Jiaoqing

    2016-04-01

    The catalyst-free metal organic vapor phase epitaxial growth of InP nanowires on silicon (001) substrate is investigated using selectively grown GaAs buffer layers in V-shaped trenches. A yield up to 70% of nanowires is self-aligned in uncommon directions under the optimized growth conditions. The evolution mechanism of self-aligned directions for nanowires is discussed and demonstrated. Using this growth method, we can achieve branched and direction switched InP nanowires by varying the V/III ratio in situ. The structure of the nanowires is characterized by scanning electron microscope and transmission electron microscopy measurements. The crystal structure of the InP nanowires is stacking-faults-free wurtzite with its c axis perpendicular to the nanowire axis.

  2. Improved heteroepitaxial MBE GaN growth with a Ga metal buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yihwan; Subramanya, Sudhir G.; Krueger, Joachim; Siegle, Henrik; Shapiro, Noad; Armitage, Robert; Feick, Henning; Weber, Eicke R.; Kisielowski, Christian; Yang, Yi; Cerrina, Franco

    2000-05-15

    We demonstrate that the use of pure gallium (Ga) as a buffer layer results in improved crystal quality of GaN epilayers grown by plasma-assisted molecular beam epitaxy on c-plane sapphire. The resulting epilayers show electron Hall mobilities as high as 400 cm 2 /Vs at a background carrier concentration of 4 x 10 17 cm -3 , an outstanding value for an MBE-grown GaN layer on sapphire. Structural properties are also improved; the asymmetric (101) X-ray rocking curve width is drastically reduced with respect to that of the reference GaN epilayer grown on a low-temperature GaN buffer layer. Nitrided Ga metal layers were investigated for different Ga deposition time. These layers can be regarded as templates for the subsequent Ga main layer growth. It was found that there is an optimum Ga metal layer deposition time for improving the electron mobility in the epilayer. Heating of the Ga metal layer to the epilayer growth temperature under nitrogen plasma is found to be sufficient to produce highly oriented GaN crystals. However, nonuniform surface morphology and incomplete surface coverage were observed after nitridation of comparatively thick Ga metal layers. This is shown to be the reason for the decreasing electron mobility of the epilayers as the Ga metal layer thickness exceeds the optimum value.

  3. Improved heteroepitaxial MBE GaN growth with a Ga metal buffer layer

    International Nuclear Information System (INIS)

    We demonstrate that the use of pure gallium (Ga) as a buffer layer results in improved crystal quality of GaN epilayers grown by plasma-assisted molecular beam epitaxy on c-plane sapphire. The resulting epilayers show electron Hall mobilities as high as 400 cm 2 /Vs at a background carrier concentration of 4 x 10 17 cm -3 , an outstanding value for an MBE-grown GaN layer on sapphire. Structural properties are also improved; the asymmetric (101) X-ray rocking curve width is drastically reduced with respect to that of the reference GaN epilayer grown on a low-temperature GaN buffer layer. Nitrided Ga metal layers were investigated for different Ga deposition time. These layers can be regarded as templates for the subsequent Ga main layer growth. It was found that there is an optimum Ga metal layer deposition time for improving the electron mobility in the epilayer. Heating of the Ga metal layer to the epilayer growth temperature under nitrogen plasma is found to be sufficient to produce highly oriented GaN crystals. However, nonuniform surface morphology and incomplete surface coverage were observed after nitridation of comparatively thick Ga metal layers. This is shown to be the reason for the decreasing electron mobility of the epilayers as the Ga metal layer thickness exceeds the optimum value

  4. Ultrathin films of YBaCuO grown on YSZ substrates with a new buffer layer Nd-Cu-O

    OpenAIRE

    Chui, TC; Tang, WH; Gao, J.

    1999-01-01

    YSZ is one of the most widely used substrates to grow oxide superconducting thin films. However, the large lattice mismatch and occurrence of intermediate layer often degrade the quality of grown films. We used a new buffer material, neodymium copper oxide (Nd2 CuO4), to improve the quality of YBCO ultrathin films grown on YSZ. Good superconducting transitions have been obtained on these films with thickness 10-12 nanometers. Such a Nd2CuO 4 layer has a stable crystal structure and behaves as...

  5. Application of a mixed metal oxide catalyst to a metallic substrate

    Science.gov (United States)

    Sevener, Kathleen M. (Inventor); Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Wisner, Daniel L. (Inventor)

    2009-01-01

    A method for applying a mixed metal oxide catalyst to a metallic substrate for the creation of a robust, high temperature catalyst system for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in propulsion systems. The method begins by forming a prepared substrate material consisting of a metallic inner substrate and a bound layer of a noble metal intermediate. Alternatively, a bound ceramic coating, or frit, may be introduced between the metallic inner substrate and noble metal intermediate when the metallic substrate is oxidation resistant. A high-activity catalyst slurry is applied to the surface of the prepared substrate and dried to remove the organic solvent. The catalyst layer is then heat treated to bind the catalyst layer to the surface. The bound catalyst layer is then activated using an activation treatment and calcinations to form the high-activity catalyst system.

  6. Stress of electroless copper deposits on insulating and metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Brüning, Ralf, E-mail: rbruening@mta.ca [Physics Department, Mount Allison University, Sackville, New Brunswick E4L 1E6 (Canada); Sibley, Allison; Sharma, Tanu; Brown, Delilah A.; Demay, Thibault [Physics Department, Mount Allison University, Sackville, New Brunswick E4L 1E6 (Canada); Brüning, Frank; Bernhard, Tobias [Atotech Deutschland GmbH, Erasmusstrasse 20, 10553 Berlin (Germany)

    2014-08-28

    In the fabrication of printed circuit boards, electroless copper is plated on insulating substrates. However, data for film stress by substrate bending are frequently obtained with metal substrates. We compare the stress evolution on an insulating substrate (acrylonitrile butadiene styrene) with results from commercial Ni–Fe and Cu–Fe alloy test strips, as well as X-ray diffraction based strain data. Tests were done with two plating bath formulations, one with and one without added nickel. Substrate type and condition determine the stress near the beginning of plating. Stress of the Ni-free films depends more strongly on the substrate material. Further, when the samples are cooled from the bath operating temperature to room temperature, the thermal contraction of the insulating substrate compresses the plated thin copper film. The measured stress change agrees with the change predicted by calculation. Data correction methods are discussed, and other substrate materials can be tested readily with the method employed here. - Highlights: • We report stress of electroless Cu deposits on insulating and metal substrates. • The final deposit stress is substrate-independent. • The final deposit stress and the X-ray diffraction based strain agree. • The stress change due to the thermal contraction of the substrate is observed. • Plating bath type, substrate and surface preparation alter the stress.

  7. Preparation of a Novel Ce0.9La0.1O2/Gd2Zr2O7 Buffer Layer Stack on NiW Alloy Substrates by the MOD Route

    DEFF Research Database (Denmark)

    Yue, Zhao; Grivel, Jean-Claude; Abrahamsen, Asger Bech;

    2011-01-01

    An optimized buffer layer architecture prepared by a metal organic deposition method on biaxially textured metallic substrate is proposed and developed successfully. The major achievement of this work is to choose a ${\\rm Ce}_{0.9}{\\rm La}_{0.1}{\\rm O}_{2}$ layer as cap layer that possesses an...

  8. Comparison of different pathways in metamorphic graded buffers on GaAs substrate: Indium incorporation with surface roughness

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rahul, E-mail: rkp203@gmail.com [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Mukhopadhyay, P. [Rajendra Mishra School of Engineering Entrepreneurship, Indian Institute of Technology, Kharagpur 721302 (India); Bag, A.; Jana, S. Kr. [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Chakraborty, A. [Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur 721 302 (India); Das, S.; Mahata, M. Kr. [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Biswas, D. [Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur 721 302 (India)

    2015-01-01

    Highlights: • In(Al,Ga)As metamorphic buffers on GaAs have been grown. • Surface morphology, strain relaxation and compositional variation have been studied. • Al containing buffers shows inferior surface roughness. • Surface roughness modulates the indium incorporation rate. - Abstract: In this work, compositionally graded In(Al,Ga)As metamorphic buffers (MBs) on GaAs substrate have been grown by MBE through three different paths. A comparative study has been done to comprehend the effect of underlying MB on the constant composition InAlAs healing layer by analyzing the relaxation behaviour, composition and surface morphology of the grown structures. The compositional variation between the constant composition healing layers on top of graded MB has been observed in all three samples although the growth conditions have been kept same. Indium incorporation rate has been found to be dependent on underlying MB. By combining the result of atomic force microscopy, photo-luminescence and X-ray reciprocal space mapping, varying surface roughness has been proposed as the probable driving force behind different Indium incorporation rate.

  9. Comparison of different pathways in metamorphic graded buffers on GaAs substrate: Indium incorporation with surface roughness

    International Nuclear Information System (INIS)

    Highlights: • In(Al,Ga)As metamorphic buffers on GaAs have been grown. • Surface morphology, strain relaxation and compositional variation have been studied. • Al containing buffers shows inferior surface roughness. • Surface roughness modulates the indium incorporation rate. - Abstract: In this work, compositionally graded In(Al,Ga)As metamorphic buffers (MBs) on GaAs substrate have been grown by MBE through three different paths. A comparative study has been done to comprehend the effect of underlying MB on the constant composition InAlAs healing layer by analyzing the relaxation behaviour, composition and surface morphology of the grown structures. The compositional variation between the constant composition healing layers on top of graded MB has been observed in all three samples although the growth conditions have been kept same. Indium incorporation rate has been found to be dependent on underlying MB. By combining the result of atomic force microscopy, photo-luminescence and X-ray reciprocal space mapping, varying surface roughness has been proposed as the probable driving force behind different Indium incorporation rate

  10. Heteroepitaxial growth of nonpolar Cu-doped ZnO thin film on MnS-buffered (100) Si substrate

    Science.gov (United States)

    Nakamura, Tatsuru; Nguyen, Nam; Nagata, Takahiro; Takahashi, Kenichiro; Ri, Sung-Gi; Ishibashi, Keiji; Suzuki, Setsu; Chikyow, Toyohiro

    2015-06-01

    The preparation of nonpolar ZnO and Cu-doped ZnO thin films on Si substrates was studied for the application to the fabrication of green-light-emitting diodes. The use of rocksalt MnS and wurtzite AlN as buffer layers is a key technology for achieving the heteroepitaxial growth of nonpolar ZnO thin film on a (100) Si substrate. X-ray diffraction and photoluminescence measurements revealed that deposition under a high oxygen partial pressure (∼1 Torr) can enhance the nonpolar crystallization of undoped ZnO, and can simultaneously suppress the formation of defects such as oxygen vacancies. These techniques can be also applied to the growth of Cu-doped ZnO. A room-temperature photoluminescence study revealed that nonpolar [11\\bar{2}0]-oriented Cu-doped ZnO film exhibits enhanced green emission owing to the doped Cu ions.

  11. Epitaxial strontium titanate films grown by atomic layer deposition on SrTiO3-buffered Si(001) substrates

    International Nuclear Information System (INIS)

    Epitaxial strontium titanate (STO) films have been grown by atomic layer deposition (ALD) on Si(001) substrates with a thin STO buffer layer grown by molecular beam epitaxy (MBE). Four unit cells of STO grown by MBE serve as the surface template for ALD growth. The STO films grown by ALD are crystalline as-deposited with minimal, if any, amorphous SiOx layer at the STO-Si interface. The growth of STO was achieved using bis(triisopropylcyclopentadienyl)-strontium, titanium tetraisopropoxide, and water as the coreactants at a substrate temperature of 250 °C. In situ x-ray photoelectron spectroscopy (XPS) analysis revealed that the ALD process did not induce additional Si–O bonding at the STO-Si interface. Postdeposition XPS analysis also revealed sporadic carbon incorporation in the as-deposited films. However, annealing at a temperature of 250 °C for 30 min in moderate to high vacuum (10−6–10−9 Torr) removed the carbon species. Higher annealing temperatures (>275 °C) gave rise to a small increase in Si–O bonding, as indicated by XPS, but no reduced Ti species were observed. X-ray diffraction revealed that the as-deposited STO films were c-axis oriented and fully crystalline. A rocking curve around the STO(002) reflection gave a full width at half maximum of 0.30° ± 0.06° for film thicknesses ranging from 5 to 25 nm. Cross-sectional transmission electron microscopy revealed that the STO films were continuous with conformal growth to the substrate and smooth interfaces between the ALD- and MBE-grown STO. Overall, the results indicate that thick, crystalline STO can be grown on Si(001) substrates by ALD with minimal formation of an amorphous SiOx layer using a four-unit-cell STO buffer layer grown by MBE to serve as the surface template.

  12. Process for forming a metal compound coating on a substrate

    International Nuclear Information System (INIS)

    This patent describes a method of coating a substrate with a thin layer of a metal compound by forming a dispersion of an electrophoretically active organic colloid and a precursor of the metal compound in an electrolytic cell in which the substrate is an electrode. Upon application of an electric potential, the electrode is coated with a mixture of the organic colloid and the precursor to the metal compound, and the coated substrate is then heated in the presence of an atmosphere or vacuum to decompose the organic colloid and form a coating of either a combination of metal compound and carbon, or optionally forming a porous metal compound coating by heating to a temperature high enough to chemically react the carbon

  13. Strontium Titanate Buffer Layers on Cu/33%Ni Substrates using a Novel Solution Chemistry

    DEFF Research Database (Denmark)

    Pallewatta, Pallewatta G A P; Yue, Zhao; Hui, Tian;

    2013-01-01

    textured Cu/33%Ni substrates using dip-coating in a precursor solution followed by drying and annealing under controlled oxygen partial pressures. The control of the ambient atmosphere during annealing is an important experimental issue in order to achieve thin films with high quality surface texture. We...

  14. Characterization of PZT thin films on metal substrates

    International Nuclear Information System (INIS)

    stresses within the films. The magnitude of the lattice distortion is independent of the crystallite size and its extent is generally smaller for crystallites in Nd-doped films than for such in undoped films. After the detailed analysis of the development of the boundary layer between metal substrate and PZT-film, it is identified as a non-ferroelectric, dielectric buffer-layer containing crystalline NiO und NiCr2O4, different chromium oxides and Pb2(CrO4)O between the PZT film and the conductive substrate significantly diminishing the resulting dielectric properties of the system. By applying a non-stoichiometric La0,75Sr0,2MnO3 (ULSM)-electrode below the PZT-film, a better electrical contact is achieved, the (001)-orientation in undoped films is enhanced and narrow P-E-hysteresis loops can be obtained. (orig.)

  15. Effects of Varied Cleaning Methods on Ni-5% W Substrate for Dip-Coating of Water-based Buffer Layers: An X-ray Photoelectron Spectroscopy Study

    OpenAIRE

    Isabel Van Driessche; Ruben Hühne; Els Bruneel; Vyshnavi Narayanan

    2012-01-01

    This work describes various combinations of cleaning methods involved in the preparation of Ni-5% W substrates for the deposition of buffer layers using water-based solvents. The substrate has been studied for its surface properties using X-ray photoelectron spectroscopy (XPS). The contaminants in the substrates have been quantified and the appropriate cleaning method was chosen in terms of contaminants level and showing good surface crystallinity to further consider them for depositing chemi...

  16. Energy buffering of DNA structure fails when Escherichia coli runs out of substrate

    DEFF Research Database (Denmark)

    Jensen, Peter Ruhdal; Loman, Leine; Petra, Bob; Coehn, Van Der Weijkden; Westerhoff, Dhans V.

    1995-01-01

    in the absence of growth substrate, since rifampin had virtually no effect on the plasmid linking number. To examine whether DNA supercoiling depends more strongly on the cellular energy state at low (ATP)/(ADP) ratios than at high ratios, we used cells that were already at a low energy state after...... number of our reporter plasmid (corresponding to a small decrease in negative supercoiling). However, when cells depleted their carbon and energy source, the ensuing drop in energy state was accompanied by a strong increase in linking number. This increase was not due to reduced transcription of the DNA...... substrate depletion; after the addition of an uncoupler to these cells, the (ATP)/(ADP) ratio decreased further, which resulted in a strong increase in plasmid linking number. Our results suggest that the strong thermodynamic control of DNA supercoiling takes over at low (ATP)/(ADP) ratios, whereas at high...

  17. Influence of the deposition techniques on the quality of the epitaxial buffer layers on textured Ni substrates

    Energy Technology Data Exchange (ETDEWEB)

    Fabbri, F.; Boffa, V.; Celentano, G.; Ciontea, L.; Galluzzi, V.; Petrisor, T. [ENEA, Rome (Italy). Centro Ricerche Frascati; Ceresara, S. [Centro Innovazione Lecco (Italy); Scardi, P. [Univ. di Trento (Italy). Dipt. di Ingegneria dei Materiali

    1999-04-20

    In order to fabricate high temperature superconducting tapes for power applications, the authors have analyzed different buffer layer architectures grown on textured Ni substrates suitable for YBCO deposition. Due to its optimal lattice matching the studied structures present as top layer a CeO{sub 2} film. The deposition of CeO{sub 2} on Ni substrates was performed by pulsed laser ablation and by e-beam evaporation at different temperatures. The films obtained by the two deposition techniques have not optimal structural properties, having a polycrystalline component. The misorientation of CeO{sub 2} is probably due to the formation of NiO at the interface between the film and the substrate during the deposition process even if no oxygen is introduced. In order to prevent Ni oxidation an intermediate 2000 {angstrom} Pd thick film was deposited by e-beam. Furthermore, the lattice mismatch between Pd and CeO{sub 2} is smaller than that between Ni and CeO{sub 2}. The Pd layer inhibits nickel oxide formation and improves the CeO{sub 2} epitaxial growth: the XRD pattern contains only the (001) peaks of Pd and CeO{sub 2}. SEM analysis on CeO{sub 2}/Pd/Ni shows a smooth surface free of cracks, contrary to that observed for CeO{sub 2}/Ni structure.

  18. Influence of the deposition techniques on the quality of the epitaxial buffer layers on textured Ni substrates

    International Nuclear Information System (INIS)

    In order to fabricate high temperature superconducting tapes for power applications, the authors have analyzed different buffer layer architectures grown on textured Ni substrates suitable for YBCO deposition. Due to its optimal lattice matching the studied structures present as top layer a CeO2 film. The deposition of CeO2 on Ni substrates was performed by pulsed laser ablation and by e-beam evaporation at different temperatures. The films obtained by the two deposition techniques have not optimal structural properties, having a polycrystalline component. The misorientation of CeO2 is probably due to the formation of NiO at the interface between the film and the substrate during the deposition process even if no oxygen is introduced. In order to prevent Ni oxidation an intermediate 2000 angstrom Pd thick film was deposited by e-beam. Furthermore, the lattice mismatch between Pd and CeO2 is smaller than that between Ni and CeO2. The Pd layer inhibits nickel oxide formation and improves the CeO2 epitaxial growth: the XRD pattern contains only the (001) peaks of Pd and CeO2. SEM analysis on CeO2/Pd/Ni shows a smooth surface free of cracks, contrary to that observed for CeO2/Ni structure

  19. Effect of CoSi2 buffer layer on structure and magnetic properties of Co films grown on Si (001) substrate

    International Nuclear Information System (INIS)

    Buffer layer provides an opportunity to enhance the quality of ultrathin magnetic films. In this paper, Co films with different thickness of CoSi2 buffer layers were grown on Si (001) substrates. In order to investigate morphology, structure, and magnetic properties of films, scanning tunneling microscope (STM), low energy electron diffraction (LEED), high resolution transmission electron microscopy (HRTEM), and surface magneto-optical Kerr effect (SMOKE) were used. The results show that the crystal quality and magnetic anisotropies of the Co films are strongly affected by the thickness of CoSi2 buffer layers. Few CoSi2 monolayers can prevent the interdiffusion of Si substrate and Co film and enhance the Co film quality. Furthermore, the in-plane magnetic anisotropy of Co film with optimal buffer layer shows four-fold symmetry and exhibits the two-jumps of magnetization reversal process, which is the typical phenomenon in cubic (001) films. (paper)

  20. Investigation of ZnO thin films deposited on ferromagnetic metallic buffer layer by molecular beam epitaxy toward realization of ZnO-based magnetic tunneling junctions

    International Nuclear Information System (INIS)

    Deposition of ZnO thin films on a ferromagnetic metallic buffer layer (Co3Pt) by molecular beam epitaxy technique was investigated for realization of ZnO-based magnetic tunneling junctions with good quality hexagonal ZnO films as tunnel barriers. For substrate temperature of 600 °C, ZnO films exhibited low oxygen defects and high electrical resistivity of 130 Ω cm. This value exceeded that of hexagonal ZnO films grown by sputtering technique, which are used as tunnel barriers in ZnO-MTJs. Also, the effect of oxygen flow during deposition on epitaxial growth conditions and Co3Pt surface oxidation was discussed.

  1. Magnetic anisotropy of crystalline Fe films grown on (001) GaAs substrates using Ge buffer layers

    Science.gov (United States)

    Bac, Seul-Ki; Lee, Hakjoon; Lee, Sangyeop; Choi, Seonghoon; Yoo, Taehee; Lee, Sanghoon; Liu, X.; Furdyna, J. K.

    2016-05-01

    Magnetic anisotropy of Fe films grown on (001) GaAs substrates using Ge buffer layers were investigated by planar Hall effect measurements. In addition to phenomena arising from dominant cubic symmetry of the Fe specimen, the study of angular dependence of magnetization reversal revealed breaking of this symmetry in the form of systematic asymmetric shifts of magnetic hysteresis loops around the crystallographic directions. We ascribe such symmetry breaking to an admixture of uniaxial anisotropy associated with the [100] direction in the Fe film. To determine the parameters associated with this uniaxial anisotropy, we quantitatively analyze the asymmetric shifts of the hysteresis loop centers from the directions. Even though the value of these parameters turns out to be relatively small compared to that of the cubic anisotropy (by about two orders of magnitude), they survive up to room temperature.

  2. Influence of double AlN buffer layers on the qualities of GaN films prepared by metal-organic chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Lin Zhi-Yu; Hao Yue; Zhang Jin-Cheng; Zhou Hao; Li Xiao-Gang; Meng Fan-Na; Zhang Lin-Xia; Ai Shan; Xu Sheng-Rui; Zhao Yi

    2012-01-01

    In this paper we report that the GaN thin film is grown by metal-organic chemical vapour deposition on a sapphire (0001) substrate with double AlN buffer layers.The buffer layer consists of a low-temperature (LT) AlN layer and a high-temperature (HT) AlN layer that are grown at 600 ℃ and 1000 ℃,respectively.It is observed that the thickness of the LT-AlN layer drastically influences the quality of GaN thin film,and that the optimized 4.25-min-LT-AlN layer minimizes the dislocation density of GaN thin film.The reason for the improved properties is discussed in this paper.

  3. Improvement in the quality of ZnTe epilayers grown on GaAs substrates by introducing a low-temperature buffer layer

    International Nuclear Information System (INIS)

    The effects of a low-temperature ZnTe buffer layer on the crystallinity and surface roughness of ZnTe epilayers grown on (100) GaAs substrates by metalorganic vapor phase epitaxy are investigated. X-ray rocking curves, Raman spectra, and atomic force microscopy analysis results prove that both the crystallinity and surface roughness of ZnTe epilayers can be markedly improved by introducing a low-temperature ZnTe buffer layer, and that the thickness of the low-temperature ZnTe buffer layer is critical for obtaining a high-crystallinity ZnTe epilayer with a smooth surface. (author)

  4. Analysis and optimization of oxide buffer layers related to YBCO films deposited by CSD and MOCVD on biaxially textured NiW substrates

    International Nuclear Information System (INIS)

    The studies based on epitaxial buffer layers of CeO2 and Yttria-stabilised ZrO2 (YSZ) having been deposited on biaxially textured nickel substrates using thermal reactive evaporation and rf sputtering in continuous deposition processes in reel-to-reel systems. Starting from the well known architecture of CeO2/YSZ/CeO2 the thickness of the different buffer layers was varied. Misorientation, porosity and roughness was analyzed and optimized for YBCO deposition by MOCVD und CSD. The grain morphology and the behavior of the grain boundary networks in YBCO coated conductors have been shown to depend on both the YBCO deposition method and the buffers layer. The possibility of using only one and two buffers layer and conductive layers of perovskite type was studied. X-ray-diffraction, SEM and TEM have been used to investigate the microstructure of both the buffer layers and the YBCO films. Optimal growth conditions of YBCO for the different buffer layers have been determined. YBCO films were deposited by CSD, MOCVD and for comparison by high pressure dc sputtering, resulting on CeO2/YSZ/CeO2 buffered substrates Jc values higher than 2 MA/cm2. The resulting superconducting properties were measured by inductive characterization and by Hall probe measurements of the magnetic field due to induced magnetization currents. (orig.)

  5. LSMO thin films with high metal–insulator transition temperature on buffered SOI substrates for uncooled microbolometers

    Energy Technology Data Exchange (ETDEWEB)

    Chromik, Š., E-mail: stefan.chromik@savba.sk [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Štrbík, V.; Dobročka, E. [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Roch, T. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 84248 Bratislava (Slovakia); Rosová, A.; Španková, M.; Lalinský, T.; Vanko, G.; Lobotka, P. [Institute of Electrical Engineering, SAS, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Ralbovský, M. [Slovak Institute of Metrology, Karloveská 63, 842 55 Bratislava (Slovakia); Choleva, P. [Vorarlberg University of Applied Sciences, Dornbirn A-6850 (Austria)

    2014-09-01

    Highlights: • SOI substrate for uncooled bolometer. • LSMO thin films on Bi{sub 4}Ti{sub 3}O{sub 12}/CeO{sub 2}/YSZ/SOI substrate. • The highest resistivity of metal–insulator transition is at temperature T{sub P} above 400 K. • TCR coefficient about 3.4% K{sup −1} at 325 K. • Rotation of Bi{sub 4}Ti{sub 3}O{sub 12} and LSMO films of 45° with regard to YSZ and SOI substrate. - Abstract: La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) thin films have been grown by a pulsed laser deposition (PLD) on Bi{sub 4}Ti{sub 3}O{sub 12}(BTO)/CeO{sub 2}/YSZ buffered silicon-on-insulator (SOI) substrates. We compare the properties of these films with results of other authors. We analyse structural properties of LSMO/BTO/CeO{sub 2}/YSZ/SOI multilayer structure prepared using PLD. Electrical measurements have shown that the temperature corresponding to maximum of resistance derivative (operating temperature of a microbolometer) is about 330 K (well above room temperature) and the highest resistivity of metal–insulator transition is at temperature (T{sub P}) above 400 K. Temperature coefficient of the resistance (TCR) has achieved values of 3.4% K{sup −1} at 325 K for some LSMO films. Transmission electron microscopy analysis has confirmed epitaxial growth of all the layers and showed a mosaic character of the LSMO films due to strain relaxation.

  6. Tuning Fluorescence Direction with Plasmonic Metal–Dielectric– Metal Substrates

    OpenAIRE

    Choudhury, Sharmistha Dutta; Badugu, Ramachandram; Nowaczyk, Kazimierz; Ray, Krishanu; Lakowicz, Joseph R.

    2013-01-01

    Controlling the emission properties of fluorophores is essential for improving the performance of fluorescence-based techniques in modern biochemical research, medical diagnosis, and sensing. Fluorescence emission is isotropic in nature, which makes it difficult to capture more than a small fraction of the total emission. Metal– dielectric–metal (MDM) substrates, discussed in this Letter, convert isotropic fluorescence into beaming emission normal to the substrate. This improves fluorescence ...

  7. High temperature coefficient of resistance of low-temperature-grown VO2 films on TiO2-buffered SiO2/Si (100) substrates

    International Nuclear Information System (INIS)

    The introduction of a TiO2 buffer layer significantly improved the temperature coefficient of resistance (TCR), a measure of the sharpness of the metal–insulator transition, for films of VO2 grown on SiO2/Si (100) substrates at growth temperatures below 670 K. X-ray diffraction and Raman scattering measurements revealed that polycrystalline VO2 films were formed on the TiO2-buffered substrates at low temperatures below 600 K, whereas amorphous films were formed at these temperatures on SiO2/Si (100) substrates without a TiO2 buffer layer. Electron microscopy studies confirmed that the TiO2 buffer layer enhanced the grain growth of VO2 films at low growth temperatures. The VO2 films grown at 600 K on TiO2-buffered substrates showed a large TCR of more than 80%/K as a result of the improved crystallinity and grain size of the VO2 films. Our results provide an effective approach toward the integration of VO2-based devices onto Si platforms at process temperatures below 670 K

  8. Spectroscopic Ellipsometry Measurements of Wurtzite Gallium Nitride Surfaces as a Function of Buffered Oxide Etch Substrate Submersion

    Science.gov (United States)

    Szwejkowski, Chester; Constantin, Costel; Duda, John; Hopkins, Patrick; Optical Studies of GaN interfaces Collaboration

    2013-03-01

    Gallium nitride (GaN) is considered the most important semiconductor after the discovery of silicon. Understanding the optical properties of GaN surfaces is imperative in determining the utility and applicability of this class of materials to devices. In this work, we present preliminary results of spectroscopic ellipsometry measurements as a function of surface root mean square (RMS). We used commercially available 5mm x 5mm, one side polished GaN (3-7 μm)/Sapphire (430 μm) substrates that have a wurtzite crystal structure and they are slightly n-type doped. The GaN substrates were cleaned with Acetone (20 min)/Isopropanol(20 min)/DI water (20 min) before they were submerged into Buffered Oxide Etch (BOE) for 10s - 60s steps. This BOE treatment produced RMS values of 1-30 nm as measured with an atomic force microscope. Preliminary qualitative ellipsometric measurements show that the complex refractive index and the complex dielectric function decrease with an increase of RMS. More measurements need to be done in order to provide explicit quantitative results. This work was supported by the 4-VA Collaborative effort between James Madison University and University of Virginia.

  9. Materials properties and dislocation dynamics in InAsP compositionally graded buffers on InP substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jandl, Adam, E-mail: jandl@mit.edu; Bulsara, Mayank T.; Fitzgerald, Eugene A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave. Cambridge, Massachusetts 02139 (United States)

    2014-04-21

    The properties of InAs{sub x}P{sub 1−x} compositionally graded buffers grown by metal organic chemical vapor deposition are investigated. We report the effects of strain gradient (ε/thickness), growth temperature, and strain initiation sequence (gradual or abrupt strain introduction) on threading dislocation density, surface roughness, epi-layer relaxation, and tilt. We find that gradual introduction of strain causes increased dislocation densities (>10{sup 6}/cm{sup 2}) and tilt of the epi-layer (>0.1°). A method of abrupt strain initiation is proposed which can result in dislocation densities as low as 1.01 × 10{sup 5} cm{sup −2} for films graded from the InP lattice constant to InAs{sub 0.15}P{sub 0.85}. A model for a two-energy level dislocation nucleation system is proposed based on our results.

  10. Materials properties and dislocation dynamics in InAsP compositionally graded buffers on InP substrates

    Science.gov (United States)

    Jandl, Adam; Bulsara, Mayank T.; Fitzgerald, Eugene A.

    2014-04-01

    The properties of InAsxP1-x compositionally graded buffers grown by metal organic chemical vapor deposition are investigated. We report the effects of strain gradient (ɛ/thickness), growth temperature, and strain initiation sequence (gradual or abrupt strain introduction) on threading dislocation density, surface roughness, epi-layer relaxation, and tilt. We find that gradual introduction of strain causes increased dislocation densities (>106/cm2) and tilt of the epi-layer (>0.1°). A method of abrupt strain initiation is proposed which can result in dislocation densities as low as 1.01 × 105 cm-2 for films graded from the InP lattice constant to InAs0.15P0.85. A model for a two-energy level dislocation nucleation system is proposed based on our results.

  11. Study of the Nucleation and Growth of YBCO on Oxide Buffered Metallic Tapes

    Energy Technology Data Exchange (ETDEWEB)

    Solovyov, Vyacheslav

    2009-04-10

    The CRADA collaboration concentrated on developing the scientific understanding of the factors necessary for commercialization of high temperature superconductors (HTS) based on the YBCO coated conductor technology for electric power applications. The project pursued the following objectives: 1. Establish the correlations between the YBCO nuclei density and the properties of the CeO{sub 2} layer of the RABiTS{trademark} template; 2. Compare the nucleation and growth of e-beam and MOD based precursors on the buffered RABiTS{trademark} templates and clarify the materials science behind the difference; and 3. Explore routes for the optimization of the nucleation and growth of thick film MOD precursors in order to achieve high critical current densities in thick films. The CRADA work proceeded in two steps: 1. Detailed characterization of epitaxial ceria layers on “model” substrates, such as (001) YSZ and on RABiTS tapes; and 2. Study of YBCO nucleation on well-defined substrates and on long-length RABiTS.

  12. Perpendicularly magnetized (001)-textured D022 MnGa films grown on an (Mg0.2Ti0.8)O buffer with thermally oxidized Si substrates

    International Nuclear Information System (INIS)

    We report the growth of (001)-textured polycrystalline D022 MnGa films with perpendicular magnetic anisotropy (PMA) on thermally oxidized Si substrates using an (Mg0.2Ti0.8)O (MTO) buffer layer. The ordered D022 MnGa film grown at the optimum substrate temperature of 530 °C on the MTO buffer layer shows PMA with magnetization of 80 kA/m, PMA energy density of 0.28 MJ/m3, and coercivity of 2.3 T. The scanning transmission electron microscope analysis confirms the formation of a highly (001)-textured structure and the elementally sharp interfaces between the MTO layer and the MnGa layer. The achieved D022 MnGa PMA films on an amorphous substrate will provide the possible pathway of integration of a Mn-based PMA film into Si-based substrates

  13. Effect of a ZnO buffer layer on the properties of epitaxial ZnO:Ga films deposited on c-sapphire substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhiyun, E-mail: zhangzhiyun01@163.com [School of Materials Science and Engineering, Xi’an University of Science and Technology, Xi’an, Shaanxi Province 710054 (China); Bao, Chonggao [State Key Laboratory for Mechanical Behaviour of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi Province 710049 (China); Yi, Dawei [School of Materials Science and Engineering, Xi’an University of Science and Technology, Xi’an, Shaanxi Province 710054 (China); Yang, Bo [No. 95 Binhai Road, Jiaojiang, Taizhou, Zhejiang Province 318000 (China); Li, Qun; Hou, Shuzeng [State Key Laboratory for Mechanical Behaviour of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi Province 710049 (China); Han, Z.H. [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an, Shaanxi Province 710068 (China)

    2014-09-01

    Highlights: • The lowest resistivity of 1.2 × 10{sup –4} Ω cm was obtained at a ZnO buffered substrate. • The characteristic of c-axis oriented texture grows up at different substrates. • Two kinds of stacking faults were observed at Fourier-filtered images. • Origin and consequences of stacking faults were discussed. • Lower defect density of film has a benefit effect on the resistivity. - Abstract: Bi-layer ZnO films with 2 wt.% Al (AZO; ZnO:Al) and 4 wt.% Ga-doped (GZO; ZnO:Ga) were deposited on the non-buffered and buffered c(0 0 0 1)-sapphire(Al{sub 2}O{sub 3}) substrates respectively by Pulsed Laser Deposition (PLD). The effect of a ZnO buffer layer on the crystallinity and electrical properties of the GZO thin films was investigated. X-ray Diffraction (XRD) peaks and High Resolution Transmission Electron Microscopy (HRTEM) studies showed that the GZO thin film on a buffered substrate was epitaxially grown with an orientation relationship of (0 0 0 1) [112{sup ¯}0]{sub GZO}||(0001)[112{sup ¯}0]{sub Al{sub 2O{sub 3}}}. However, GZO thin film on a non-buffered substrate was grown as a monocrystalline hexagonal wurtzite phase with c-axis preferred, out-of-plane orientation, and random in-plane orientation. The electrical resistivity of the GZO thin films was improved by introducing a ZnO buffer layer from 2.2 × 10{sup -4} Ω cm to 1.2 × 10{sup -4} Ω cm, respectively. In a word, it was found in the films that more preferred c-axis orientation texture and reduction of the defects such as stacking faults and dislocations, with introducing a ZnO buffer layer. It was seen that the ZnO buffer layer had a great influence on the orientation and defect density of GZO thin films from X-ray Diffraction (XRD) peaks and High Resolution Transmission Electron Microscopy (HRTEM) images.

  14. A resin-buffered nutrient solution for controlling metal speciation in the algal bottle assay

    Energy Technology Data Exchange (ETDEWEB)

    Verheyen, L., E-mail: liesbeth.verheyen@ees.kuleuven.be [Division of Soil and Water Management, Department of Earth and Environmental Sciences, K.U.Leuven, Kasteelpark Arenberg 20 - box 2459, 3001 Heverlee (Belgium); Merckx, R.; Smolders, E. [Division of Soil and Water Management, Department of Earth and Environmental Sciences, K.U.Leuven, Kasteelpark Arenberg 20 - box 2459, 3001 Heverlee (Belgium)

    2012-06-15

    Metal speciation in solution is uncontrolled during algal growth in the traditional algal bottle assay. A resin-buffered nutrient solution was developed to overcome this problem and this was applied to test the effect of chloride (Cl{sup -}) on cadmium (Cd) uptake. Standard nutrient solution was enriched with 40 mM of either NaNO{sub 3} or NaCl, and was prepared to contain equal Cd{sup 2+} but varying dissolved Cd due to the presence of CdCl{sub n}{sup 2-n} complexes. Both solutions were subsequently used in an algal assay in 100 mL beakers that contained only the solution (designated '-R') or contained the solution together with a cation exchange sulfonate resin (2 g L{sup -1}, designated '+R') as a deposit on the bottom of the beaker. Pseudokirchneriella subcapitata was grown for 72 h (1.4 Multiplication-Sign 10{sup 5}-1.4 Multiplication-Sign 10{sup 6} cells mL{sup -1}) in stagnant solution and shaken three times a day. Growth was unaffected by the presence of the resin (p > 0.05). The Cd concentrations in solution of the -R devices decreased with 50-58% of initial values due to Cd uptake. No such changes were found in the +R devices or in abiotic controls. Cd uptake was unaffected by either NaNO{sub 3} or NaCl treatment in the +R device, confirming that Cd{sup 2+} is the preferred Cd species in line with the general concept of metal bioavailability. In contrast, Cd uptake in the -R devices was two-fold larger in the NaCl treatment than in the NaNO{sub 3} treatment (p < 0.001), suggesting that CdCl{sub n}{sup 2-n} complexes are bioavailable in this traditional set-up. However this bioavailability is partially, but not completely, an apparent one, because of the considerable depletion of solution {sup 109}Cd in this set-up. Resin-buffered solutions are advocated in the algal bottle assay to control trace metal supply and to better identify the role of metal complexes on bioavailability.

  15. A resin-buffered nutrient solution for controlling metal speciation in the algal bottle assay

    International Nuclear Information System (INIS)

    Metal speciation in solution is uncontrolled during algal growth in the traditional algal bottle assay. A resin-buffered nutrient solution was developed to overcome this problem and this was applied to test the effect of chloride (Cl−) on cadmium (Cd) uptake. Standard nutrient solution was enriched with 40 mM of either NaNO3 or NaCl, and was prepared to contain equal Cd2+ but varying dissolved Cd due to the presence of CdCln2−n complexes. Both solutions were subsequently used in an algal assay in 100 mL beakers that contained only the solution (designated “−R”) or contained the solution together with a cation exchange sulfonate resin (2 g L−1, designated “+R”) as a deposit on the bottom of the beaker. Pseudokirchneriella subcapitata was grown for 72 h (1.4 × 105–1.4 × 106 cells mL−1) in stagnant solution and shaken three times a day. Growth was unaffected by the presence of the resin (p > 0.05). The Cd concentrations in solution of the −R devices decreased with 50–58% of initial values due to Cd uptake. No such changes were found in the +R devices or in abiotic controls. Cd uptake was unaffected by either NaNO3 or NaCl treatment in the +R device, confirming that Cd2+ is the preferred Cd species in line with the general concept of metal bioavailability. In contrast, Cd uptake in the −R devices was two-fold larger in the NaCl treatment than in the NaNO3 treatment (p n2−n complexes are bioavailable in this traditional set-up. However this bioavailability is partially, but not completely, an apparent one, because of the considerable depletion of solution 109Cd in this set-up. Resin-buffered solutions are advocated in the algal bottle assay to control trace metal supply and to better identify the role of metal complexes on bioavailability.

  16. Enhanced electrical and magnetic properties in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films deposited on CaTiO{sub 3}-buffered silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, C. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Méchin, L.; Guillet, B.; Wu, S.; Routoure, J.-M. [Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, (GREYC-UMR 6072), CNRS-ENSICAEN—Université de Caen Basse-Normandie, 6 Boulevard Maréchal Juin, 14050 Caen Cedex (France); Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Katz, M.; Pan, X. Q. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Mercone, S. [Laboratoire de Sciences des Procédés et des Matériaux, UPR3407, CNRS, Institut Galilee, Universite Paris-Nord, Villetaneuse (France); Schubert, J.; Zander, W. [Peter Grünberg Institute (PGI9-IT), JARA-Fundamentals of Future Information Technology, Research Centre Jülich, Jülich D-52425 (Germany); Misra, R. [Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Schiffer, P. [Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); and others

    2015-06-01

    We investigate the suitability of an epitaxial CaTiO{sub 3} buffer layer deposited onto (100) Si by reactive molecular-beam epitaxy (MBE) for the epitaxial integration of the colossal magnetoresistive material La{sub 0.7}Sr{sub 0.3}MnO{sub 3} with silicon. The magnetic and electrical properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films deposited by MBE on CaTiO{sub 3}-buffered silicon (CaTiO{sub 3}/Si) are compared with those deposited on SrTiO{sub 3}-buffered silicon (SrTiO{sub 3}/Si). In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO{sub 3} buffer layer. These results are relevant to device applications of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films on silicon substrates.

  17. Enhanced electrical and magnetic properties in La0.7Sr0.3MnO3 thin films deposited on CaTiO3-buffered silicon substrates

    Directory of Open Access Journals (Sweden)

    C. Adamo

    2015-06-01

    Full Text Available We investigate the suitability of an epitaxial CaTiO3 buffer layer deposited onto (100 Si by reactive molecular-beam epitaxy (MBE for the epitaxial integration of the colossal magnetoresistive material La0.7Sr0.3MnO3 with silicon. The magnetic and electrical properties of La0.7Sr0.3MnO3 films deposited by MBE on CaTiO3-buffered silicon (CaTiO3/Si are compared with those deposited on SrTiO3-buffered silicon (SrTiO3/Si. In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO3 buffer layer. These results are relevant to device applications of La0.7Sr0.3MnO3 thin films on silicon substrates.

  18. Effects of annealing in Be/W and Be/C bilayers deposited on Si(0 0 1) substrates with Fe buffer layers

    International Nuclear Information System (INIS)

    Highlights: • Be/W, Be/C layers deposited by TVA on Si substrate with thin sputtered Fe buffers. • Fe films were hydrogenated (300 °C); Be/W and Be/C were annealed in vacuum (600 °C). • Increase of oxidation near the surface; the hydrogenation reduces oxidation. • The annealing induces high interatomic diffusion all over the structure. • Mixed phases are formed by annealing: Fe–Be, Fe–C; no Fe–W phases are evidenced. - Abstract: Atomic intermixing processes in relation to structural aspects and phase formation in Be based thin films subjected to different annealing treatments simulating the case of re-deposited layered structures on plasma facing components in nuclear fusion devices are reported. Accordingly, bilayers of Be/W and Be/C have been deposited on Si(0 0 1) substrates with Fe buffer layers. The Fe films have been prepared by radiofrequency sputtering and further processed by annealing in hydrogen atmosphere at 300 °C, for 90 min, at a pressure of 10 bars of H2. After the Be/W and Be/C bilayer deposition by means of thermionic vacuum arc method, annealing in vacuum at 600 °C, for 10 min has been applied to the complex structures. The influence of annealing on the phase composition and atomic intermixing processes in the complex structures has been studied by means of X-ray photoelectron spectroscopy (XPS) and conversion electron Mössbauer spectroscopy (CEMS). The layered structures present an oxidation gradient with oxide phases in the uppermost layers and non-oxidized phases in the lower layers, as observed from the XPS data. The CEMS results revealed that the as-deposited structures contain a main metallic Fe phase and secondary superparamagnetic Fe oxide phases at the Fe/Be interface, while annealed samples present a large contribution of Fe–Be and Fe–C mixtures. The annealing treatment induces considerable atomic interdiffusion, strongly dependent on the nature of the upper layer. In the case of Be/W system, the annealing

  19. Effects of annealing in Be/W and Be/C bilayers deposited on Si(0 0 1) substrates with Fe buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Schinteie, G. [National Institute of Materials Physics, P.O. Box MG-7, 77125 Bucharest-Magurele (Romania); Greculeasa, S.G., E-mail: simona.greculeasa@infim.ro [National Institute of Materials Physics, P.O. Box MG-7, 77125 Bucharest-Magurele (Romania); Bucharest University, Faculty of Physics, 077125 Bucharest-Magurele (Romania); Palade, P.; Lungu, G.A. [National Institute of Materials Physics, P.O. Box MG-7, 77125 Bucharest-Magurele (Romania); Porosnicu, C.; Jepu, I.; Lungu, C.P. [National Institute for Laser, Plasma and Radiation Physics, 77125 Bucharest-Magurele (Romania); Filoti, G.; Kuncser, V. [National Institute of Materials Physics, P.O. Box MG-7, 77125 Bucharest-Magurele (Romania)

    2015-02-15

    Highlights: • Be/W, Be/C layers deposited by TVA on Si substrate with thin sputtered Fe buffers. • Fe films were hydrogenated (300 °C); Be/W and Be/C were annealed in vacuum (600 °C). • Increase of oxidation near the surface; the hydrogenation reduces oxidation. • The annealing induces high interatomic diffusion all over the structure. • Mixed phases are formed by annealing: Fe–Be, Fe–C; no Fe–W phases are evidenced. - Abstract: Atomic intermixing processes in relation to structural aspects and phase formation in Be based thin films subjected to different annealing treatments simulating the case of re-deposited layered structures on plasma facing components in nuclear fusion devices are reported. Accordingly, bilayers of Be/W and Be/C have been deposited on Si(0 0 1) substrates with Fe buffer layers. The Fe films have been prepared by radiofrequency sputtering and further processed by annealing in hydrogen atmosphere at 300 °C, for 90 min, at a pressure of 10 bars of H{sub 2}. After the Be/W and Be/C bilayer deposition by means of thermionic vacuum arc method, annealing in vacuum at 600 °C, for 10 min has been applied to the complex structures. The influence of annealing on the phase composition and atomic intermixing processes in the complex structures has been studied by means of X-ray photoelectron spectroscopy (XPS) and conversion electron Mössbauer spectroscopy (CEMS). The layered structures present an oxidation gradient with oxide phases in the uppermost layers and non-oxidized phases in the lower layers, as observed from the XPS data. The CEMS results revealed that the as-deposited structures contain a main metallic Fe phase and secondary superparamagnetic Fe oxide phases at the Fe/Be interface, while annealed samples present a large contribution of Fe–Be and Fe–C mixtures. The annealing treatment induces considerable atomic interdiffusion, strongly dependent on the nature of the upper layer. In the case of Be/W system, the annealing

  20. Control of metamorphic buffer structure and device performance of InxGa1−xAs epitaxial layers fabricated by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Using a step-graded (SG) buffer structure via metal-organic chemical vapor deposition, we demonstrate a high suitability of In0.5Ga0.5As epitaxial layers on a GaAs substrate for electronic device application. Taking advantage of the technique’s precise control, we were able to increase the number of SG layers to achieve a fairly low dislocation density (∼106 cm−2), while keeping each individual SG layer slightly exceeding the critical thickness (∼80 nm) for strain relaxation. This met the demanded but contradictory requirements, and even offered excellent scalability by lowering the whole buffer structure down to 2.3 μm. This scalability overwhelmingly excels the forefront studies. The effects of the SG misfit strain on the crystal quality and surface morphology of In0.5Ga0.5As epitaxial layers were carefully investigated, and were correlated to threading dislocation (TD) blocking mechanisms. From microstructural analyses, TDs can be blocked effectively through self-annihilation reactions, or hindered randomly by misfit dislocation mechanisms. Growth conditions for avoiding phase separation were also explored and identified. The buffer-improved, high-quality In0.5Ga0.5As epitaxial layers enabled a high-performance, metal-oxide-semiconductor capacitor on a GaAs substrate. The devices displayed remarkable capacitance–voltage responses with small frequency dispersion. A promising interface trap density of 3 × 1012 eV−1 cm−2 in a conductance test was also obtained. These electrical performances are competitive to those using lattice-coherent but pricey InGaAs/InP systems. (paper)

  1. Controlled growth of vertically aligned carbon nanotubes on metal substrates

    Science.gov (United States)

    Gao, Zhaoli

    Carbon nanotube (CNT) is a fascinating material with extraordinary electrical thermal and mechanical properties. Growing vertically aligned CNT (VACNT) arrays on metal substrates is an important step in bringing CNT into practical applications such as thermal interface materials (TIMs) and microelectrodes. However, the growth process is challenging due to the difficulties in preventing catalyst diffusion and controlling catalyst dewetting on metal substrates with physical surface heterogeneity. In this work, the catalyst diffusion mechanism and catalyst dewetting theory were studied for the controlled growth of VACNTs on metal substrates. The diffusion time of the catalyst, the diffusion coefficients for the catalyst in the substrate materials and the number density of catalyst nanoparticles after dewetting are identified as the key parameters, based on which three strategies are developed. Firstly, a fast-heating catalyst pretreatment strategy was used, aiming at preserving the amount of catalyst prior to CNT growth by reducing the catalyst diffusion time. The catalyst lifetime is extended from half an hour to one hour on a patterned Al thin film and a VACNT height of 106 mum, about twenty fold of that reported in the literature, was attained. Secondly, a diffusion barrier layer strategy is employed for a reduction of catalyst diffusion into the substrate materials. Enhancement of VACNT growth on Cu substrates was achieved by adopting a conformal Al2O 3 diffusion barrier layer fabricated by a specially designed atomic layer deposition (ALD) system. Lastly, a novel catalyst glancing angle deposition (GLAD) strategy is performed to manipulate the morphology of a relatively thick catalyst on metal substrates with physical surface heterogeneity, aiming to obtain uniform and dense catalyst nanoparticles after dewetting in the pretreatment process for enhanced VACNT growth. We are able to control the VACNT growth conditions on metal substrates in terms of their

  2. Cube Texture Formation of Cu-33at.%Ni Alloy Substrates and CeO2 Buffer Layer for YBCO Coated Conductors

    DEFF Research Database (Denmark)

    Tian, Hui; Li, Suo Hong; Ru, Liang Ya;

    2014-01-01

    Cube texture formation of Cu-33 at.%Ni alloy substartes and CeO2 buffer layer prepared by chemical solution deposition on the textured substrate were investigated by electron back scattered diffraction (EBSD) and XRD technics systematically. The results shown that a strong cube textured Cu-33at...... epitaxially grown CeO2 buffer layer was 95 % (<10°), and the FWHM values of phi-scan and omega-scan being 6.98° and 5.92°, respectively....

  3. Formation of conductive spontaneous via holes in AlN buffer layer on n+Si substrate by filling the vias with n-AlGaN by metal organic chemical vapor deposition and application to vertical deep ultraviolet photo-sensor

    Directory of Open Access Journals (Sweden)

    N. Kurose

    2014-12-01

    Full Text Available We have grown conductive aluminum nitride (AlN layers using the spontaneous via holes formation technique on an n+-Si substrate for vertical-type device fabrication. The size and density of the via holes are controlled through the crystal growth conditions used for the layer, and this enables the conductance of the layer to be controlled. Using this technique, we demonstrate the fabrication of a vertical-type deep ultraviolet (DUV photo-sensor. This technique opens up the possibility of fabrication of monolithically integrated on-chip DUV sensors and DUV light-emitting devices (LEDs, including amplifiers, controllers and other necessary functional circuits, on a Si substrate.

  4. Graded plasma spraying of premixed metalceramic powders on metallic substrates

    Science.gov (United States)

    Lima, C. R. C.; Trevisan, R.-E.

    1997-06-01

    The mismatch between the thermal expansion coefficients of ceramics and metals and the differential stresses it causes at the interface create problems in metal to ceramic joining. Research has been con-ducted to solve this problem in thermal barrier coating technology. Previous studies have considered met-al-ceramic multilayers or graded-coatings, which include a metallic bond coat. In this study, a graded plasma-sprayed metal-ceramic coating is developed using the deposition of premixed metal and ceramic powders without the conventional metallic bond coat. Influences of thickness variations, number, and composition of the layers are investigated. Coatings are prepared by atmospheric plasma-spraying on In-conel 718 superalloy substrates. Ni-Cr-Al and ZrO2 -8 % Y2O3 powders are used for plasma spraying. Ad-hesive and cohesive strength of the coatings are determined. The concentration profile of the elements is determined by x-ray energy-dispersive analysis. The microstructure and morphology of the coatings are investigated by optical and scanning electron microscopy (SEM). Results show that the mixed metal-ce-ramic coating obtained with the deposition of premixed powders is homogeneous. The morphology and microstructure of the coatings are considered satisfactory.

  5. Interaction of silicene and germanene with non-metallic substrates

    Science.gov (United States)

    Houssa, M.; Scalise, E.; van den Broek, B.; Lu, A.; Pourtois, G.; Afanas'ev, V. V.; Stesmans, A.

    2015-01-01

    By using first-principles simulations, we investigate the interaction of silicene and germanene with various non-metallic substrates. We first consider weak van der Waals interactions between the 2D layers and dichalcogenide substrates, like MoX2 (X=S, Se, Te). The buckling of the silicene or germanene layer is correlated to the lattice mismatch between the 2D material and the MoX2 template. The electronic properties of silicene or germanene on these different templates then largely depend on the buckling of the 2D material layer: highly buckled silicene or germanene on MoS2 are predicted to be metallic, while low buckled silicene on MoTe2 is predicted to be semi-metallic, with preserved Dirac cones at the K points. We next study the covalent bonding of silicene and germanene on (0001) ZnS and ZnSe surfaces. On these substrates, silicene or germanene are found to be semiconducting. Remarkably, the nature and magnitude of their energy band gap can be controlled by an out-of-plane electric field.

  6. Epitaxial growth of nobel metals on alumina substrates

    International Nuclear Information System (INIS)

    The influence of the reconstructed (0001) α-Al2O3 surface on the heteroepitaxial growth and adhesion properties of small metal particles (gold, silver and copper) of noncontinuous thin films has been investigated. The crystallographic structure and morphology of substrate surfaces were examined by Reflection High Energy Electron Diffraction and Atomic Force Microscopy techniques. The reconstructed surfaces are terminated by one or more Aluminum atomic layers. By means of the Transmission Electronic Microscopy, the various granulometric and lattice parameters variations are investigated during different stages of the heteroepitaxial growth of metallic thin films. We estimated the adhesion energy values for each case of metal//(0001)α-Al2O3 interfaces by two methods: the maximum cluster density and the Lifshits theory of Van der Waals energy of interfaces. The results of both methods are in good agreement. Using these methods, we found interfaces Hamaker's constants values and we investigated all the heteroepitaxial growth steps.(author)

  7. Compatibility of the selective area growth of GaN nanowires on AlN-buffered Si substrates with the operation of light emitting diodes

    International Nuclear Information System (INIS)

    AlN layers with thicknesses between 2 and 14 nm were grown on Si(111) substrates by molecular beam epitaxy. The effect of the AlN layer thickness on the morphology and nucleation time of spontaneously formed GaN nanowires (NWs) was investigated by scanning electron microscopy and line-of-sight quadrupole mass spectrometry, respectively. We observed that the alignment of the NWs grown on these layers improves with increasing layer thickness while their nucleation time decreases. Our results show that 4 nm is the smallest thickness of the AlN layer that allows the growth of well-aligned NWs with short nucleation time. Such an AlN buffer layer was successfully employed, together with a patterned SiOx mask, for the selective-area growth (SAG) of vertical GaN NWs. In addition, we fabricated light-emitting diodes (LEDs) from NW ensembles that were grown by means of self-organization phenomena on bare and on AlN-buffered Si substrates. A careful characterization of the optoelectronic properties of the two devices showed that the performance of NW-LEDs on bare and AlN-buffered Si is similar. Electrical conduction across the AlN buffer is facilitated by a high number of grain boundaries that were revealed by transmission electron microscopy. These results demonstrate that grainy AlN buffer layers on Si are compatible both with the SAG of GaN NWs and LED operation. Therefore, this study is a first step towards the fabrication of LEDs on Si substrates based on homogeneous NW ensembles. (paper)

  8. Effect of Ga2O3 buffer layer thickness on the properties of Cu/ITO thin films deposited on flexible substrates

    International Nuclear Information System (INIS)

    Cu and Cu/ITO films were prepared on polyethylene terephthalate (PET) substrates with a Ga2O3 buffer layer using radio frequency (RF) and direct current (DC) magnetron sputtering. The effect of Cu layer thickness on the optical and electrical properties of the Cu film deposited on a PET substrate with a Ga2O3 buffer layer was studied, and an appropriate Cu layer thickness of 4.2 nm was obtained. Changes in the optoelectrical properties of Cu(4.2 nm)/ITO(30 nm) films were investigated with respect to the Ga2O3 buffer layer thickness. The optical and electrical properties of the Cu/ITO films were significantly influenced by the thickness of the Ga2O3 buffer layer. A maximum transmission of 86%, sheet resistance of 45 Ω/□ and figure of merit of 3.96 × 10−3 Ω−1 were achieved for Cu(4.2 nm)/ITO(30 nm) films with a Ga2O3 layer thickness of 15 nm. (semiconductor materials)

  9. Development of biaxially textured buffer layers on rolled-Ni substrates for high current YBa2Cu3O7-y coated conductors

    International Nuclear Information System (INIS)

    This paper describes the development of 3 buffer layer architectures with good biaxial textures on rolled-Ni substrates using vacuum processing techniques. The techniques include pulsed laser ablation, e-beam evaporation, dc and rf magnetron sputtering. The first buffer layer architecture consists of an epitaxial laminate of Ag/Pd(Pt)/Ni. The second buffer layer consists of an epitaxial laminate of CeO2/Pd/Ni. The third alternative buffer layer architecture consists of an epitaxial laminate of YSZ/CeO2/Ni. The cube (100) texture in the Ni was produced by cold rolling followed by recrystallization. Crystallographic orientations of the Pd, Ag, CeO2, and YSZ films grown were all (100). We recently demonstrated a critical- current density of 0.73x106 A/cm2 at 77 K and zero field on 1.4 μm thick YBa2Cu3O7-y (YBCO) film. This film was deposited by pulsed laser ablation on a YBCO/YSZ/CeO2/Ni substrate

  10. Buffer layers for REBCO films for use in superconducting devices

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Amit; Wee, Sung-Hun

    2014-06-10

    A superconducting article includes a substrate having a biaxially textured surface. A biaxially textured buffer layer, which can be a cap layer, is supported by the substrate. The buffer layer includes a double perovskite of the formula A.sub.2B'B''O.sub.6, where A is rare earth or alkaline earth metal and B' and B'' are different transition metal cations. A biaxially textured superconductor layer is deposited so as to be supported by the buffer layer. A method of making a superconducting article is also disclosed.

  11. The growth of AgGaTe2 layers on glass substrates with Ag2Te buffer layer by closed space sublimation method

    International Nuclear Information System (INIS)

    The AgGaTe2 layer growth was performed by the closed space sublimation method on the Mo/glass substrate. The Ag2Te buffer layer was inserted between AgGaTe2 and Mo layers, to improve the quality of grown layers. Crystallographic properties were analyzed by x-ray diffraction (XRD), and the surface morphologies were analyzed by scanning electron microscopy (SEM). The Ag2Te layer grown on the Mo/glass exhibited a membrane filter structure from the SEM observation. XRD spectra of layers grown with and without the buffer layer were compared. The AgGaTe2 layer with the Ag2Te buffer layer exhibited peaks originating from AgGaTe2, and a very strong diffraction peak of 112 was observed. On the other hand, it was cleared that the layer grown without the buffer layer exhibited no strong peaks associated with AgGaTe2, but Ga-Te compounds. From this, crystallographic properties of the AgGaTe2 layer were drastically improved by the insertion of the Ag2Te buffer layer. Moreover, the surface morphology exhibited a smooth surface when the Ag2Te buffer layer was inserted. The nucleation site density of AgGaTe2 was probably increased since the membrane filter structure exhibited numbers of kinks at the edge. Chemical reaction between Ga and Mo was also eliminated. It was cleared that the insertion of the buffer layer and its surface morphology were an important parameter to grow high quality AgGaTe2 layers. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. The growth of AgGaTe{sub 2} layers on glass substrates with Ag{sub 2}Te buffer layer by closed space sublimation method

    Energy Technology Data Exchange (ETDEWEB)

    Uruno, Aya; Usui, Ayaka; Takeda, Yuji; Inoue, Tomohiro [Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kobayashi, Masakazu [Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051 (Japan)

    2015-06-15

    The AgGaTe{sub 2} layer growth was performed by the closed space sublimation method on the Mo/glass substrate. The Ag{sub 2}Te buffer layer was inserted between AgGaTe{sub 2} and Mo layers, to improve the quality of grown layers. Crystallographic properties were analyzed by x-ray diffraction (XRD), and the surface morphologies were analyzed by scanning electron microscopy (SEM). The Ag{sub 2}Te layer grown on the Mo/glass exhibited a membrane filter structure from the SEM observation. XRD spectra of layers grown with and without the buffer layer were compared. The AgGaTe{sub 2} layer with the Ag{sub 2}Te buffer layer exhibited peaks originating from AgGaTe{sub 2}, and a very strong diffraction peak of 112 was observed. On the other hand, it was cleared that the layer grown without the buffer layer exhibited no strong peaks associated with AgGaTe{sub 2}, but Ga-Te compounds. From this, crystallographic properties of the AgGaTe{sub 2} layer were drastically improved by the insertion of the Ag{sub 2}Te buffer layer. Moreover, the surface morphology exhibited a smooth surface when the Ag{sub 2}Te buffer layer was inserted. The nucleation site density of AgGaTe{sub 2} was probably increased since the membrane filter structure exhibited numbers of kinks at the edge. Chemical reaction between Ga and Mo was also eliminated. It was cleared that the insertion of the buffer layer and its surface morphology were an important parameter to grow high quality AgGaTe{sub 2} layers. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Improved breakdown voltage of AlGaN/GaN HEMTs grown on Si substrates using partially Mg-doped GaN buffer layer by MOCVD

    Institute of Scientific and Technical Information of China (English)

    LAU; KeiMay

    2010-01-01

    AlGaN/GaN high electron mobility transistors(HEMTs) were grown on Si substrates by MOCVD.In the HEMT structure,a 1 μm GaN buffer layer was partially doped with Mg in an attempt to increase the resistivity and minimize the buffer leakage.The AlGaN/GaN HEMTs grown on undoped and partially Mg-doped GaN buffer layers were processed and the DC characteristics of the devices were characterized for comparing the effect of Mg doping.For the device with the partially Mg-doped GaN buffer layer,a lower drain leakage current density of 55.8 nA/mm,a lower gate leakage current density of 2.73 μA/mm,and a higher off-state breakdown voltage of 104 V were achieved with device dimensions Lg/Wg/Lgs/Lgd=1/10/1/1 μm,better than the device with the undoped GaN buffer layer,which has a higher drain leakage current density of 9.2 μA/mm,a higher gate leakage current density of 91.8 μA/mm,and a lower off-state breakdown voltage of 87 V with the same device dimensions.

  14. Microstructure and texture evolution of CeO{sub 2} buffer layers prepared via dip-coating sol-gel method on IBAD-YSZ/Hastelloy substrates

    Energy Technology Data Exchange (ETDEWEB)

    Du, P. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)], E-mail: honey00@mails.tsinghua.edu.cn; Wang, S.S.; Chen, H.; Wang, Z.; Sun, J.C.; Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Schmidt, W.; Neumuller, H.W. [Siemens AG, CT PS 3, Erlangen 91052 (Germany)

    2007-10-01

    We have fabricated CeO{sub 2} buffer layers on IBAD-YSZ/Hastelloy substrates via dip-coating sol-gel method using inorganic salts as starting materials. X-ray diffraction (XRD), scanning electron microscopy (SEM) and scanning probe microscope (SPM) were applied to investigate the influential factors in film formation and texture evolution. Flat, crack-free CeO{sub 2} films with sharp (0 0 2) c-axis orientation and good texture were obtained by carefully controlling the precursor solution quality, dip-coating and heating process. Compared with IBAD-YSZ/Hastelloy substrates, textures of CeO{sub 2} films were effectively improved.

  15. Structural characterisation of BaTiO3 thin films deposited on SrRuO3/YSZ buffered silicon substrates and silicon microcantilevers

    OpenAIRE

    Colder, Héloïse; Domengès, B.; Jorel, Corentin; Marie, P.; Boisserie, M.; Guillon, Samuel; Nicu, Liviu; Galdi, Alice; Mechin, Laurence

    2014-01-01

    We report on the progress towards an all epitaxial oxide layer technology on silicon substrates for epitaxial piezoelectric microelectromechanical systems. (101)-oriented epitaxial tetragonal BaTiO3 (BTO) thin films were deposited at two different oxygen pressures, 5.10 2 mbar and 5.10 3 mbar, on SrRuO3/Yttria-stabilized zirconia (YSZ) buffered silicon substrates by pulsed laser deposition. The YSZ layer full (001) orientation allowed the further growth of a fully (110)-oriented conductive Sr...

  16. Preparation and mechanoluminescent properties of SrAl2O4:Eu film grown on silicon substrate using double buffer layers

    International Nuclear Information System (INIS)

    In this paper, we utilized double layer method to prepare SrAl2O4:Eu (SAOE) film on silicon substrate (400). The Al2O3 layer (about 200 nm) was used as a hetero-buffer layer to eliminate the large difference of crystal lattice and thermal mismatch between the SAOE and silicon substrate. Thin SAOE layer (about 600 nm) was grown on Al2O3 layer as homo-buffer layer to reduce internal stress during film growth process. On double buffer layers, continuous sputtering formed about 1.5 μm SAOE film. The resulting thick SAOE/Al2O3/Si film possessed both excellent photoluminescence (PL) and mechanoluminescence (ML) properties. The similarity of PL and ML spectra suggested that PL and ML both originated from same emitting center of Eu2+. The strong ML intensity showed that the as-prepared SAOE film can be regarded as an indicator to detect stress distribution of an object. The thermoluminescent (ThL) results indicated that a large amount of trapped electrons existing in the resulting film answered for the strong ML intensity. - Highlights: • Double-layer method used to prepare SrAl2O4:Eu film on silicon substrate (400). • SrAl2O4:Eu film with excellent photoluminescent and mechanoluminescent properties • The film can be used as an indicator to detect stress distribution of an object

  17. Assessment of Automotive Coatings Used on Different Metallic Substrates

    Directory of Open Access Journals (Sweden)

    W. Bensalah

    2014-01-01

    Full Text Available Four epoxy primers commonly used in the automotive industry were applied by gravity pneumatic spray gun over metallic substrates, specifically, steel, electrogalvanized steel, hot-dip galvanized steel, and aluminum. A two-component polyurethane resin was used as topcoat. To evaluate the performance of the different coating systems, the treated panels were submitted to mechanical testing using Persoz hardness, impact resistance, cupping, lattice method, and bending. Tribological properties of different coating systems were conducted using pin on disc machine. Immersion tests were carried out in 5% NaCl and immersion tests in 3% NaOH solutions. Results showed which of the coating systems is more suitable for each substrate in terms of mechanical, tribological, and anticorrosive performance.

  18. Deposition of carbon nanostructures on metal substrates at atmospheric pressure

    Science.gov (United States)

    Dimitrov, Zh; Nikovski, M.; Kiss'ovski, Zh

    2016-03-01

    The microwave-plasma-enhanced CVD of carbon nanostructures at atmospheric pressure allows shorter deposition times and reduces the complexity of the experimental set-up. In our study, the substrate temperature was varied in a wide range (300 – 700 C) using microwave plasma heating, as well as an additional heater. The distance between the substrate and the plasma flame was also varied in order to establish the conditions for an efficient deposition process, the latter being carried out at specific argon/hydrogen/methane gas mixtures. Optical measurements of the plasma flame spectrum were conducted to obtain the gas temperature and the plasma density and to analyze the existence of reactive species. The carbon nanostructures deposited on the metal samples were investigated by SEM. The relation between the morphology and the gas-discharge conditions is discussed.

  19. Flexible metal-insulator-metal capacitors on polyethylene terephthalate plastic substrates

    Science.gov (United States)

    Hota, M. K.; Bera, M. K.; Maiti, C. K.

    2012-10-01

    Realization of flexible electronic devices on polyethylene terephthalate flexible plastic substrates is reported. Metal-insulator-metal capacitors have been fabricated using radio frequency sputtered deposited thin films of Nb2O5 on the flexible substrate. Good electrical characteristics have been obtained in terms of quadratic voltage coefficient of capacitance, high capacitance density (˜ 11 fF µm-2), high dielectric constant (˜37) and low dissipation factor (<0.1). Besides, in repetitive bending test, the devices show excellent electrical stability and high mechanical flexibility due to the high ductility of niobium and low-temperature processing used in this study.

  20. Characterization of ZrO2 buffer layers for sequentially evaporated Y-Ba-CuO on Si and Al2O3 substrates

    Science.gov (United States)

    Valco, George J.; Rohrer, Norman J.; Pouch, John J.; Warner, Joseph D.; Bhasin, Kul B.

    1988-01-01

    Thin film high temperature superconductors have the potential to change the microwave technology for space communications systems. For such applications it is desirable that the films be formed on substrates such as Al2O3 which have good microwave properties. The use of ZrO2 buffer layers between Y-Ba-Cu-O and the substrate has been investigated. These superconducting films have been formed by multilayer sequential electron beam evaporation of Cu, BaF2 and Y with subsequent annealing. The three layer sequence of Y/BaF2/Cu is repeated four times for a total of twelve layers. Such a multilayer film, approximately 1 micron thick, deposited directly on SrTiO3 and annealed at 900 C for 45 min produces a film with a superconducting onset of 93 K and critical temperature of 85 K. Auger electron spectroscopy in conjunction with argon ion sputtering was used to obtain the distribution of each element as a function of depth for an unannealed film, the annealed film on SrTiO3 and annealed films on ZrO2 buffer layers. The individual layers were apparent. After annealing, the bulk of the film on SrTiO3 is observed to be fairly uniform while films on the substrates with buffer layers are less uniform. The Y-Ba-Cu-O/ZrO2 interface is broad with a long Ba tail into the ZrO2, suggesting interaction between the film and the buffer layer. The underlying ZrO2/Si interface is sharper. The detailed Auger results are presented and compared with samples annealed at different temperatures and durations.

  1. Effect of substrate temperatures on evaporated In2S3 thin film buffer layers for Cu(In,Ga)Se2 solar cells

    International Nuclear Information System (INIS)

    For the realization of vacuum in-line process in the fabrication of Cu(In,Ga)Se2 (CIGS) solar cells, In2S3 thin film buffer layers for CIGS have been deposited on glasses and CIGS layers with a thickness of about 650 Å by thermal evaporation process. During the thermal evaporation, the temperature of the substrate was varied from room temperature to 500 °C by heating and the grown In2S3 films were investigated and analyzed in terms of the optimized buffer layer for CIGS solar cells. From the results of scanning electron microscope and X-ray diffraction, the In2S3 thin film deposited at a higher substrate temperature showed the larger grain size and the films have amorphous structural characteristics. Although the structural characteristics such as the atomic ratio of In to S and transmittance of the In2S3 thin films were not proportional to temperature, it was possible to obtain the large optical band gap of In2S3 films of about 3.8–3.9 eV enough to be used as the buffer layer of CIGS. - Highlights: • In2S3 films were deposited at various substrate temperatures by thermal evaporation. • The atomic ratio of In to S in the In2S3 film has the highest value at 300 °C. • The In2S3 film has a band gap of about 3.8 eV because of its amorphous structure. • The In2S3 film is expected to be used as a buffer layer by in-line vacuum process

  2. Improved high temperature integration of Al2O3 on MoS2 by using a metal oxide buffer layer

    International Nuclear Information System (INIS)

    We deposited a metal oxide buffer layer before atomic layer deposition (ALD) of Al2O3 onto exfoliated molybdenum disulfide (MoS2) in order to accomplish enhanced integration. We demonstrate that even at a high temperature, functionalization of MoS2 by means of a metal oxide buffer layer can effectively provide nucleation sites for ALD precursors, enabling much better surface coverage of Al2O3. It is shown that using a metal oxide buffer layer not only allows high temperature ALD process, resulting in highly improved quality of Al2O3/MoS2 interface, but also leaves MoS2 intact

  3. COATING OF POLYMERIC SUBSTRATE CATALYSTS ON METALLIC SURFACES

    Directory of Open Access Journals (Sweden)

    H. HOSSEINI

    2010-12-01

    Full Text Available This article presents results of a study on coating of a polymeric substrate ca-talyst on metallic surface. Stability of coating on metallic surfaces is a proper specification. Sol-gel technology was used to synthesize adhesion promoters of polysilane compounds that act as a mediator. The intermediate layer was coated by synthesized sulfonated polystyrene-divinylbenzene as a catalyst for production of MTBE in catalytic distillation process. Swelling of catalyst and its separation from the metal surface was improved by i increasing the quantity of divinylbenzene in the resin’s production process and ii applying adhesion pro¬moters based on the sol-gel process. The rate of ethyl silicate hydrolysis was intensified by increasing the concentration of utilized acid while the conden¬sation polymerization was enhanced in the presence of OH–. Sol was formed at pH 2, while the pH should be 8 for the formation of gel. By setting the ratio of the initial concentrations of water to ethyl silicate to 8, the gel formation time was minimized.

  4. Metal oxide films on glass and steel substrates

    CERN Document Server

    Sohi, A M

    1987-01-01

    in the pH8 electrolyte supports the view that the rate limiting reduction reaction is possibly oxygen (or water) reduction although some contribution from an organic 'impurity' cannot be ruled out. Coatings of Fe sub 3 O sub 4 on mild steel have been prepared by CVD using pneumatic spraying techniques and the corrosion behaviour of coated electrodes in organic-phosphate electrolyte (pH8) has been examined. A variety of thin (10-1000nm) metal oxide films have been deposited on flat glass substrates by the pyrolysis of an aerosol of metal acetylacetonates in a suitable carrier. The optical characteristics and thickness of the films have been measured and particular interest has centered on the use of a novel pin on disc apparatus to measure the physical durability of such thin films. Characteristic friction/penetration force traces have been established for 1st Series transition metal oxide films and some ranking in terms of 'hardness' established. The use of SnO sub 2 - coated glass for electrodes in a light m...

  5. Fabrication of a strain-induced high performance NbN ultrathin film by a Nb5N6 buffer layer on Si substrate

    International Nuclear Information System (INIS)

    Lattice mismatch between NbN and silicon (Si) reduces the superconducting properties of NbN film on Si substrate, and this in turn affects the performance of devices such as the hot electron bolometer (HEB) and superconducting nanowire single photon detector (SNSPD). We have found that the superconducting properties of NbN film on Si will be significantly improved by a Nb5N6 buffer layer. The strain of the NbN film was optimized by varying the thickness of the buffer layer. With 30  nm thick Nb5N6, the zero resistance superconducting transition temperature (TC0) of a 6 nm thick NbN film on Si is up to 13.5 K and the critical current density (JC) of the film is more than 107 A cm−2. All the details of preparation, improvement and characteristics of this film are also presented. (paper)

  6. Aspartate buffer and divalent metal ions affect oxytocin in aqueous solution and protect it from degradation

    DEFF Research Database (Denmark)

    Avanti, Christina; Oktaviani, Nur Alia; Hinrichs, Wouther L.J.;

    2013-01-01

    favorable. These interactions may explain the protection of the disulfide bridge against intermolecular reactions that lead to dimerization.Mg or Zn, using 2D NOESY, TOCSY, H-C HSQC and H- N HSQC NMR spectroscopy. Almost all H, C and N resonances of oxytocin could be assigned using HSQC spectroscopy....... Furthermore, LC–MS (MS) measurements indicated that the combination of aspartate buffer and Zn2+ in particular suppressed intermolecular degradation reactions near the Cys1,6 disulfide bridge. These results lead to the hypothesis that in aspartate buffer, Zn2+ changes the conformation of oxytocin in such a...... way that the Cys1,6 disulfide bridge is shielded from its environment thereby suppressing intermolecular reactions involving this region of the molecule. To verify this hypothesis, we investigate here the conformation of oxytocin in aspartate buffer in the presence of Mg2+ or Zn2+, using 2D NOESY...

  7. Thermodynamic studies on complexation of divalent transition metal ions with some zwitterionic buffers for biochemical and physiological research

    International Nuclear Information System (INIS)

    The interaction between the zwitterionic buffers (3-[N-bis(2-hydroxyethyl)amino]-2-hydroxy propane sulfonic acid, N-(2-actamido)-2-aminoethane sulfonic acid, and 3-[(1,1-dimethyl-2-hydroxyethyl)amino]-2-hydroxy propane sulfonic acid) with some divalent transition metal ions (CuII, NiII, CoII, ZnII, and MnII) were studied at different temperatures (298.15 to 328.15) K at ionic strength I = 0.1 mol . dm-3 NaNO3 and in the presence of 10%, 30%, and 50% (w/w) dioxene by using potentiometry. The thermodynamic stability constants were calculated as well as the free energy change for the 1:1 binary complexation. The protonation constants of the zwitterionic buffers were also determined potentiometrically under the above conditions

  8. Oxidized Nano-Porous-Silicon Buffer Layers for Suppressing the Visible Photoresponsivity of ZnO Ultraviolet Photodetectors on Si Substrates

    Directory of Open Access Journals (Sweden)

    Kuen-Hsien Wu

    2014-01-01

    Full Text Available This paper demonstrated the fabrication and optoelectronic characteristics of ZnO ultraviolet (UV photodetectors fabricated on Si substrates with oxidized nano-porous-Si (ONPS buffer layers. ONPS layers were prepared on the surfaces of Si substrates by use of an electrochemical anodization technique following a rapid-thermal-oxidation process. Experimental results indicated that application of ONPS buffer layers not only improved the crystallinty of the deposited ZnO thin films but also greatly restricted the visible-to-infrared photoresponse that was generated from the light absorption of Si substrates. The developed ZnO-on-ONPS photodiodes achieved high photoresponsivity for the incident UV light of 300 ∼ 400 nm and got a large photo-to-dark current ratio up to 104 at wavelength of 375 nm under a bias of 5 V. Therefore, ZnO on ONPS provides a highly potential approach for the development of low-cost visible-blind UV photodetectors.

  9. Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate

    Science.gov (United States)

    Tuttle, J. R.; Noufi, R.; Hasoon, F. S.

    2006-05-30

    A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

  10. The effect of metal-buffer bilayer drain/source electrodes on the operational stability of the organic field effect transistors

    International Nuclear Information System (INIS)

    In this paper, we have investigated experimentally the effect of different drain/source (D/S) electrodes and charge injection buffer layers on the electrical properties and operational stability of a stilbene organic field effect transistor (OFET). The results show that the organic buffer layer of copper phthalocyanine (CuPc) considerably improves the electrical properties of the transistors, but has a negligible effect on their temporal behavior. On the other hand, inorganic metal-oxide buffer layer of molybdenum oxide (MoO3) drastically changes both the electrical properties and operational stability. The functionalities of this metal-oxide tightly depend on the properties of the D/S metallic electrodes. OFETs with Al/MoO3 as the bilayer D/S electrodes have the best electrical properties: field effect mobility μeff = 0.32 cm2 V−1 s−1 and threshold voltage VTH = − 5 V and the transistors with Ag/MoO3 have the longest operational stability. It was concluded that the chemical stability of the metal/metal-oxide or metal/organic interfaces of the bilayer D/S electrodes determine the operational stability of the OFETs. - Highlights: • The effect of buffer layers on the performance of the stilbene OFETs has been investigated. • Inorganic buffer layer improved the electrical and temporal behaviors simultaneously. • Organic buffer layer only changes the electrical properties. • Chemical stability of the interfaces determines the operational stability of the transistor

  11. Aspartate buffer and divalent metal ions affect oxytocin in aqueous solution and protect it from degradation

    NARCIS (Netherlands)

    Avanti, Christina; Oktaviani, Nur Alia; Hinrichs, Wouter L J; Frijlink, Henderik W; Mulder, Frans A A

    2013-01-01

    Oxytocin is a peptide drug used to induce labor and prevent bleeding after childbirth. Due to its instability, transport and storage of oxytocin formulations under tropical conditions is problematic. In a previous study, we have found that the stability of oxytocin in aspartate buffered formulation

  12. Charge movement in a GaN-based hetero-structure field effect transistor structure with carbon doped buffer under applied substrate bias

    Energy Technology Data Exchange (ETDEWEB)

    Pooth, Alexander, E-mail: a.pooth@bristol.ac.uk [Center for Device Thermography and Reliability, H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); IQE (Europe) Ltd., Pascal Close, St. Mellons, Cardiff CF3 0LW (United Kingdom); Uren, Michael J.; Cäsar, Markus; Kuball, Martin [Center for Device Thermography and Reliability, H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Martin, Trevor [IQE (Europe) Ltd., Pascal Close, St. Mellons, Cardiff CF3 0LW (United Kingdom)

    2015-12-07

    Charge trapping and transport in the carbon doped GaN buffer of a GaN-based hetero-structure field effect transistor (HFET) has been investigated under both positive and negative substrate bias. Clear evidence of redistribution of charges in the carbon doped region by thermally generated holes is seen, with electron injection and capture observed during positive bias. Excellent agreement is found with simulations. It is shown that these effects are intrinsic to the carbon doped GaN and need to be controlled to provide reliable and efficient GaN-based power HFETs.

  13. Charge movement in a GaN-based hetero-structure field effect transistor structure with carbon doped buffer under applied substrate bias

    International Nuclear Information System (INIS)

    Charge trapping and transport in the carbon doped GaN buffer of a GaN-based hetero-structure field effect transistor (HFET) has been investigated under both positive and negative substrate bias. Clear evidence of redistribution of charges in the carbon doped region by thermally generated holes is seen, with electron injection and capture observed during positive bias. Excellent agreement is found with simulations. It is shown that these effects are intrinsic to the carbon doped GaN and need to be controlled to provide reliable and efficient GaN-based power HFETs

  14. In vitro tensile strength of luting cements on metallic substrate.

    Science.gov (United States)

    Orsi, Iara A; Varoli, Fernando K; Pieroni, Carlos H P; Ferreira, Marly C C G; Borie, Eduardo

    2014-01-01

    The aim of this study was to determine the tensile strength of crowns cemented on metallic substrate with four different types of luting agents. Twenty human maxillary molars with similar diameters were selected and prepared to receive metallic core castings (Cu-Al). After cementation and preparation the cores were measured and the area of crown's portion was calculated. The teeth were divided into four groups based on the luting agent used to cement the crowns: zinc phosphate cement; glass ionomer cement; resin cement Rely X; and resin cement Panavia F. The teeth with the crowns cemented were subjected to thermocycling and later to the tensile strength test using universal testing machine with a load cell of 200 kgf and a crosshead speed of 0.5 mm/min. The load required to dislodge the crowns was recorded and converted to MPa/mm(2). Data were subjected to Kruskal-Wallis analysis with a significance level of 1%. Panavia F showed significantly higher retention in core casts (3.067 MPa/mm(2)), when compared with the other cements. Rely X showed a mean retention value of 1.877 MPa/mm(2) and the zinc phosphate cement with 1.155 MPa/mm(2). Glass ionomer cement (0.884 MPa/mm(2)) exhibited the lowest tensile strength value. Crowns cemented with Panavia F on cast metallic posts and cores presented higher tensile strength. The glass ionomer cement showed the lowest tensile strength among all the cements studied. PMID:25140718

  15. Metal oxide films on glass and steel substrates

    International Nuclear Information System (INIS)

    A variety of thin (10-1000nm) metal oxide films have been deposited on flat glass substrates by the pyrolysis of an aerosol of metal acetylacetonates in a suitable carrier. The optical characteristics and thickness of the films have been measured and particular interest has centered on the use of a novel pin on disc apparatus to measure the physical durability of such thin films. Characteristic friction/penetration force traces have been established for 1st Series transition metal oxide films and some ranking in terms of 'hardness' established. The use of SnO2 - coated glass for electrodes in a light modulator cell has been examined. The electrochromic behaviour of a silver matrix in DMSO electrolyte has been observed in a small glass cell and by cyclic voltammetry on a vitreous carbon electrode. Optimum conditions for practical light-shutter have been established and electrode processes elucidated. A corrosion study of mild steel in two different water/organic electrolytes of industrial importance has been carried out. Mechanisms to account for the corrosion observed have been presented. Support for the usual anodic reaction is presented Fe → Fe2+ + 2e but in the electrolyte operated at low pH film formation of a water soluble organic 'tar' has been confirmed and the proposed reaction Fe2+ + H2O → FeOH+ + H+ leads to a local increase in [H+] which accounts for the observed corrosion rate. In contrast, corrosion behaviour in the pH8 electrolyte supports the view that the rate limiting reduction reaction is possibly oxygen (or water) reduction although some contribution from an organic 'impurity' cannot be ruled out. Coatings of Fe3O4 on mild steel have been prepared by CVD using pneumatic spraying techniques and the corrosion behaviour of coated electrodes in organic-phosphate electrolyte (pH8) has been examined. (author)

  16. Deposition and Characterization of Thin Films on Metallic Substrates

    Science.gov (United States)

    Gatica, Jorge E.

    2005-01-01

    on aluminum and other metallic substrates.

  17. Increased upper critical field for nanocrystalline MoN thin films deposited on AlN buffered substrates at ambient temperature

    Science.gov (United States)

    Baskaran, R.; Thanikai Arasu, A. V.; Amaladass, E. P.; Vaidhyanathan, L. S.; Baisnab, D. K.

    2016-05-01

    Molybdenum nitride (MoN) thin films have been deposited using reactive DC magnetron sputtering on aluminum nitride buffered oxidized silicon substrates at ambient temperature. GIXRD of aluminum nitride (AlN) deposited under similar conditions has revealed the formation of wurtzite phase AlN. GIXRD characterization of molybdenum thin films deposited on AlN buffered oxidized silicon substrates has indicated the formation of nanocrystalline MoN thin films. The electrical resistivity measurements indicate MoN thin films have a superconducting transition temperature of ~8 K. The minimum transition width of the MoN thin film is 0.05 K at 0 T. The inferred upper critical field B c2(0) for these nanocrystalline MoN thin films obtained by fitting the temperature dependence of critical field with Werthamer, Helfand and Hohenberg theory lies in the range of 17–18 T which is the highest reported in literature for MoN thin films.

  18. Effects of the buffering capacity of the soil on the mobilization of heavy metals. Equilibrium and kinetics.

    Science.gov (United States)

    Villen-Guzman, Maria; Paz-Garcia, Juan M; Amaya-Santos, Gema; Rodriguez-Maroto, Jose M; Vereda-Alonso, Carlos; Gomez-Lahoz, Cesar

    2015-07-01

    Understanding the possible pH-buffering processes is of maximum importance for risk assessment and remediation feasibility studies of heavy-metal contaminated soils. This paper presents the results about the effect of the buffering capacity of a polluted soil, rich in carbonates, on the pH and on the leaching evolution of its main contaminant (lead) when a weak acid (acetic acid) or a strong one (nitric acid) are slowly added. In both cases, the behavior of lead dissolution could be predicted using available (scientifically verified freeware) models assuming equilibrium between the solid and the aqueous phase. However, the experimental results indicate that the dissolution of calcium and magnesium carbonates is kinetically controlled. These kinetic limitations affect the overall behavior, and should be considered to understand also the response of the metals under local equilibrium. The well-known BCR sequential extraction procedure was used before- and after-treatment, to fractionate the lead concentration in the soil according to its mobility. The BCR results were also in agreement with the predictions of the equilibrium model. This agreement allows new insights about the information that could be derived from the BCR fractionation analysis. PMID:25781866

  19. Silver metal colloidal film on a flexible polymer substrate

    Science.gov (United States)

    del Rocío Balaguera Gelves, Marcia; El Burai-Félix, Alia; De La Cruz-Montoya, Edwin; Jeréz Rozo, Jaqueline I.; Hernández-Rivera, Samuel P.

    2006-05-01

    A method to prepare metallic nanoparticles films in the presence of a hydrophilic copolymer with the aim of inhibiting the formation of clusters in the nanoparticles has been developed. Thin films prepared could be used in applications such as sensors development and substrates for surface-enhanced Raman spectroscopy. The synthesis of colloidal solutions of silver nanoparticles was achieved by the reduction AgNO 3 using sodium citrate with thermal treatment which results in a robust fabrication of gold and silver films. The polymeric films were prepared by polymerization 2-hydroxyethyl methacrylate with methacrylic acid (method 1). The other procedure employed (method 2) incorporated the use of polyvinyl pyrrolidone and polyethylene glycol as copolymers. A scanning electron microscope was used to provide microstructural information of coverage achieved. The ability to tune the nanocoating structure and spectral and electronic properties can be used for applications such as sensors used in the detection of explosives. Silver nanoparticles were also characterized by surface-enhanced Raman scattering (SERS), which integrates high chemical sensitivity with spectroscopic identification and has enormous potential for applications involving ultra-sensitive chemical detection. Spectra were obtained using a Renishaw RM2000 Raman Microspectrometer system operating in the visible region excitation (532 nm).

  20. Tuning molecule-substrate coupling via deposition of metal adatoms

    Science.gov (United States)

    Yang, Hung-Hsiang; Tsai, Hsu-Han; Ying, Chi-Feng; Yang, Tsung-Han; Kaun, Chao-Cheng; Chen, Chun-hsien; Lin, Minn-Tsong

    2015-11-01

    Organic-inorganic hybrids constitute an important class of functional materials. The fundamentals at the molecular levels are, however, relatively unexplored. PTCDA (perylene-3,4,9,10-tetracarboxylic dianhydride) is a colorant and extensively applied in organic-based optoelectronic devices. PTCDA/Cu(111) and Fe-PTCDA/Cu(111) metal-organic hybrid monolayers are studied by low temperature scanning tunneling microscopy and spectroscopy (STS) and density functional theory (DFT). The former exhibits Moiré pattern-modulated molecular density of states while the latter adapts a commensurate adlattice. Both imaging and spectroscopic results suggest a strong hybridization between PTCDA molecules and Cu(111) substrate. Weak PTCDA-Cu(111) coupling can be obtained by the introduction of Fe adatoms. Compared to PTCDA/Cu(111), STS spectra of Fe-PTCDA/Cu(111) exhibit a higher energy and sharper features of the frontier orbitals. Together with the DFT results, we found that the PTCDA-Cu(111) coupling is attenuated by the presence of Fe adatoms and Fe-PTCDA coordination.

  1. Electrical properties of n-type GaSb substrates and p-type GaSb buffer layers for InAs/InGaSb superlattice infrared detectors

    International Nuclear Information System (INIS)

    Lightly doped n-type GaSb substrates with p-type GaSb buffer layers are the preferred templates for growth of InAs/InGaSb superlattices used in infrared detector applications because of relatively high infrared transmission and a close lattice match to the superlattices. We report here temperature dependent resistivity and Hall effect measurements of bare substrates and substrate-p-type buffer layer structures grown by molecular beam epitaxy. Multicarrier analysis of the resistivity and Hall coefficient data demonstrate that high temperature transport in the substrates is due to conduction in both the high mobility zone center Γ band and the low mobility off-center L band. High overall mobility values indicate the absence of close compensation and that improved infrared and transport properties were achieved by a reduction in intrinsic acceptor concentration. Standard transport measurements of the undoped buffer layers show p-type conduction up to 300 K indicating electrical isolation of the buffer layer from the lightly n-type GaSb substrate. However, the highest temperature data indicate the early stages of the expected p to n type conversion which leads to apparent anomalously high carrier concentrations and lower than expected mobilities. Data at 77 K indicate very high quality buffer layers

  2. Electrical properties of n-type GaSb substrates and p-type GaSb buffer layers for InAs/InGaSb superlattice infrared detectors

    Directory of Open Access Journals (Sweden)

    W. C. Mitchel

    2015-09-01

    Full Text Available Lightly doped n-type GaSb substrates with p-type GaSb buffer layers are the preferred templates for growth of InAs/InGaSb superlattices used in infrared detector applications because of relatively high infrared transmission and a close lattice match to the superlattices. We report here temperature dependent resistivity and Hall effect measurements of bare substrates and substrate-p-type buffer layer structures grown by molecular beam epitaxy. Multicarrier analysis of the resistivity and Hall coefficient data demonstrate that high temperature transport in the substrates is due to conduction in both the high mobility zone center Γ band and the low mobility off-center L band. High overall mobility values indicate the absence of close compensation and that improved infrared and transport properties were achieved by a reduction in intrinsic acceptor concentration. Standard transport measurements of the undoped buffer layers show p-type conduction up to 300 K indicating electrical isolation of the buffer layer from the lightly n-type GaSb substrate. However, the highest temperature data indicate the early stages of the expected p to n type conversion which leads to apparent anomalously high carrier concentrations and lower than expected mobilities. Data at 77 K indicate very high quality buffer layers.

  3. Adlayer Core-Level Shifts of Random Metal Overlayers on Transition-Metal Substrates

    DEFF Research Database (Denmark)

    Ganduglia-Pirovano, M. V.; Kudrnovský, J.; Scheffler, M.

    1997-01-01

    We calculate the difference of the ionization energies of a core electron of a surface alloy, i.e., a B atom in a A(1-x)B(x) overlayer on a fee B(001) substrate, and a core electron of the clean fee B(001) surface using density-functional theory. We analyze the initial-state contributions and the...... the initial-state trends are explained in terms of the change of inter- and intra-atomic screening upon alloying. A possible role of alloying on the chemical reactivity of metal surfaces is discussed....

  4. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    (001)-oriented BiFeO 3 (BFO) thin films were grown on Sr xCa 1-xRuO 3- (SCRO; x = 1, 0.67, 0.33, 0) buffered SrTiO 3 (001) substrates using pulsed laser deposition. The microstructural, electrical, ferroelectric, and piezoelectric properties of the thin films were considerably affected by the buffer layers. The interface between the BFO films and the SCRO-buffer layer was found to play a dominant role in determining the electrical and piezoelectric behaviors of the films. We found that films grown on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  5. Epitaxial growth of YBa2Cu3O7-δ on Ni89V11 non-magnetic biaxially textured substrate using NiO as buffer layer

    International Nuclear Information System (INIS)

    The superconducting YBa2Cu3O7-δ/CeO2/NiO multilayer structure was grown in situ by pulsed-laser deposition on biaxially textured Ni89V11 non-magnetic alloy. The role of vanadium is to decrease the Curie temperature of Ni and to favour the formation of oriented NiO. The (00l)NiO buffer layer has been formed by the controlled oxidation of the Ni-V substrate under 10 mTorr oxygen pressure and at 700 deg. C. The critical current density of 0.6 MA cm-2, at 77 K and zero magnetic field, was obtained for 0.7 μm thick YBa2Cu3O7-δ films. (author)

  6. Lattice pulling effect and strain relaxation in axial (In,Ga)N/GaN nanowire heterostructures grown on GaN-buffered Si(111) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kong, X.; Trampert, A. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117, Berlin (Germany); Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M.A.; Calleja, E. [Dpto. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica, Ciudad Universitaria, 28040, Madrid (Spain)

    2015-04-01

    Transmission electron microscopy and spatially resolved electron energy-loss spectroscopy have been applied to investigate the indium distribution and the interface morphology in axial (In,Ga)N/GaN nanowire heterostructures. The ordered axial (In,Ga)N/GaN nanowire heterostructures with an indium concentration up to 80% are grown by molecular beam epitaxy on GaN-buffered Si(111) substrates. We observed a pronounced lattice pulling effect in all the nanowire samples given in a broad transition region at the interface. The lattice pulling effect becomes smaller and the (In,Ga)N/GaN interface width is reduced as the indium concentration is increased in the (In,Ga)N section. The result can be interpreted in terms of the increased plastic strain relaxation via the generation of the misfit dislocations at the interface. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Buffer-Free GeSn and SiGeSn Growth on Si Substrate Using In Situ SnD4 Gas Mixing

    Science.gov (United States)

    Mosleh, Aboozar; Alher, Murtadha; Cousar, Larry C.; Du, Wei; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Dou, Wei; Grant, Perry C.; Sun, Greg; Soref, Richard A.; Li, Baohua; Naseem, Hameed A.; Yu, Shui-Qing

    2016-04-01

    Buffer-free GeSn and SiGeSn films have been deposited on Si via a cold-wall, ultra-high vacuum chemical vapor deposition reactor using in situ gas mixing of deuterated stannane, silane and germane. Material characterization of the films using x-ray diffraction and transmission electron microscopy shows crystalline growth with an array of misfit dislocation formed at the Si substrate interface. Energy dispersive x-ray maps attained from the samples show uniform incorporation of the elements. The Z-contrast map of the high-angle annular dark-field of the film cross section shows uniform incorporation along the growth as well. Optical characterization of the GeSn films through photoluminescence technique shows reduction in the bandgap edge of the materials.

  8. The effect of metal-buffer bilayer drain/source electrodes on the operational stability of the organic field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Karimi-Alavijeh, H.R., E-mail: h.karimi@eng.ui.ac.ir [Department of Electrical Engineering, University of Isfahan, Isfahan (Iran, Islamic Republic of); Ehsani, A. [Department of Electrical and Avionics Engineering, Malek-Ashtar University of Technology, Isfahan (Iran, Islamic Republic of)

    2015-09-01

    In this paper, we have investigated experimentally the effect of different drain/source (D/S) electrodes and charge injection buffer layers on the electrical properties and operational stability of a stilbene organic field effect transistor (OFET). The results show that the organic buffer layer of copper phthalocyanine (CuPc) considerably improves the electrical properties of the transistors, but has a negligible effect on their temporal behavior. On the other hand, inorganic metal-oxide buffer layer of molybdenum oxide (MoO{sub 3}) drastically changes both the electrical properties and operational stability. The functionalities of this metal-oxide tightly depend on the properties of the D/S metallic electrodes. OFETs with Al/MoO{sub 3} as the bilayer D/S electrodes have the best electrical properties: field effect mobility μ{sub eff} = 0.32 cm{sup 2} V{sup −1} s{sup −1} and threshold voltage V{sub TH} = − 5 V and the transistors with Ag/MoO{sub 3} have the longest operational stability. It was concluded that the chemical stability of the metal/metal-oxide or metal/organic interfaces of the bilayer D/S electrodes determine the operational stability of the OFETs. - Highlights: • The effect of buffer layers on the performance of the stilbene OFETs has been investigated. • Inorganic buffer layer improved the electrical and temporal behaviors simultaneously. • Organic buffer layer only changes the electrical properties. • Chemical stability of the interfaces determines the operational stability of the transistor.

  9. Mechanism of buffer gases influence on the rate of photostimulated laser-chemical deposition from vapors on transition metal carbonyls

    International Nuclear Information System (INIS)

    A method is proposed for deactivation of the excited state of molecules of transitional-metal carbonyls due to collisions with atoms or molecules of buffer gas, enabling the explanation of the experimental results of the photostimulated laser-chemical deposition (LCD). The model is constructed according to which deactivation of the excited state as a result of a translational relaxation of the kinetic energy of fragments in the molecule during the transition. The conclusion is drawn that owing to a high correlation of the experimental results and the model calculations it is possible to use the LCD method as an analytical tool for quantitative measurements of the parameters of photochemical reactions proceeding under the action of laser radiation, in particular, constants of monomolecular decay of excited molecules

  10. Fabrication of Sr silicate buffer layer on Si(100) substrate by pulsed laser deposition using a SrO target

    Energy Technology Data Exchange (ETDEWEB)

    Imanaka, Atsuhiro; Sasaki, Tsubasa [Department of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Hotta, Yasushi, E-mail: hotta@eng.u-hyogo.ac.jp; Satoh, Shin-ichi [Department of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan and CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2014-09-01

    The authors fabricated 2 × 1 Sr-reconstructed Si(100) substrates using thin SrO layers, and used them to direct growth of crystalline perovskite oxide on Si. The SrO layers used to reconstruct the Si(100) substrates were grown by pulsed laser deposition from a SrO single crystal target, followed by postdeposition-annealing (PDA) of the SrO/Si(100) structure. In situ observations of reflective high-energy electron diffraction during PDA confirmed a 2 × 1 reconstruction of the Si surface and x-ray photoemission spectroscopy of the annealed samples confirmed the existence of Sr atoms in a silicate phase, which indicated that a 2 × 1 Sr-reconstructed Si surface was achieved. The optimal fabrication conditions were annealing at 720 °C for 1 min and an equivalent SrO layer thickness (ML{sub eq}) of 2.5 ML{sub eq}. The temperature condition was very narrow, at 720 ± 20 °C, for an acceptable product. Subsequently, the authors demonstrated the growth of crystalline SrTiO{sub 3} films on the 2 × 1 Sr-reconstructed Si(100) surfaces.

  11. Textured tape substrates from binary copper alloys with vanadium and yttrium for the epitaxial deposition of buffer and superconducting layers

    Science.gov (United States)

    Khlebnikova, Yu. V.; Rodionov, D. P.; Egorova, L. Yu.; Suaridze, T. R.

    2016-05-01

    The structure of tapes of binary Cu-0.6 wt % V and Cu-1 wt % Y alloys and texturing process of them in the course of cold deformation by rolling to 99% and subsequent recrystallizing annealing have been studied. The possibility of achieving the perfect cube texture in thin tapes made from binary copper-based alloys with vanadium and yttrium additions has in principle been shown. This opens the prospect of using them as substrates when manufacturing tapes of second-generation high-temperature superconductors. Optimum annealing conditions for the studied alloys have been determined, which have made it possible to produce the perfect biaxial texture with a content of cube {001} ± 10° grains on the surfaces of textured tapes of more than 95%.

  12. The effect of design parameters of metallic substrate on the reproducibility of SERS measurement for biosensing

    Science.gov (United States)

    Fu, Chit Yaw; Koh, Zhen Yu; Kho, Kiang Wei; S, Dinish U.; Praveen, Thoniyot; Olivo, Malini

    2009-08-01

    A successful detection of inherently weak Raman signal from molecules is possible with giant enhancement of signal by the process of surface-enhanced Raman scattering (SERS). The SERS-induced enhancement is typically achieved when the molecules adsorbed onto the surface of a noble-metal substrate with nanometric roughness. Such SERS-substrate could be economically fabricated by convective assembly of polystyrene beads followed by metal deposition. The characterization of mono-metallic substrate showed that the SERS enhancement factor increases with increasing thickness of Ag or Au, with Ag-substrate giving the greatest SERS enhancement. However, the formation of silver oxide layer could reduce the shelf-life of the Ag-substrate. Alternatively, Au is also used as the coating material owing to its chemical inertness and biocompatibility. Despite the decent enhancement of the Au-substrate, Au-layer was found to be unstable after prolonged incubation in crystal violet solution. The inherent deficiency in adhesiveness of Au to the glass limits its use as a reliable and cost-effective substrate. In an attempt to improve the SERS-substrate, bimetallic substrate was fabricated by depositing the Au-film, as a protective layer, on the Ag-substrate. In this case, the top layer of Au of the bimetallic substrate remained intact after chemical treatment. Furthermore, the bimetallic substrate was shown to give comparable level of enhancement as an Ag-substrate by choosing a proper thickness ratio of the bimetallic layers. The result suggests that the design of bimetallic substrate could be optimized to maximize the SERS enhancement while retaining a decent stability after laser illumination and chemical treatment. Our findings suggest that bimetallic substrates are potentially useful for a reliable SERS-based biosensing.

  13. Structural characterisation of BaTiO{sub 3} thin films deposited on SrRuO{sub 3}/YSZ buffered silicon substrates and silicon microcantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Colder, H.; Jorel, C., E-mail: corentin.jorel@unicaen.fr; Méchin, L. [GREYC, UMR 6072, CNRS, ENSICAEN, UCBN, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Domengès, B. [LAMIPS, CRISMAT-NXP Semiconductors-Presto Engineering laboratory, CNRS-UMR 6508, ENSICAEN, UCBN, 2 rue de la Girafe, 14 000 Caen (France); Marie, P.; Boisserie, M. [CIMAP, UMR 6252, CNRS, ENSICAEN, UCBN, CEA, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Guillon, S.; Nicu, L. [LAAS, CNRS, Univ de Toulouse, 7 avenue du Colonel Roche, 31400 Toulouse (France); Galdi, A. [GREYC, UMR 6072, CNRS, ENSICAEN, UCBN, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Department of Industrial Engineering, CNR-SPIN Salerno, Università di Salerno, 84084 Fisciano, Salerno (Italy)

    2014-02-07

    We report on the progress towards an all epitaxial oxide layer technology on silicon substrates for epitaxial piezoelectric microelectromechanical systems. (101)-oriented epitaxial tetragonal BaTiO{sub 3} (BTO) thin films were deposited at two different oxygen pressures, 5.10{sup −2} mbar and 5.10{sup −3} mbar, on SrRuO{sub 3}/Yttria-stabilized zirconia (YSZ) buffered silicon substrates by pulsed laser deposition. The YSZ layer full (001) orientation allowed the further growth of a fully (110)-oriented conductive SrRuO{sub 3} electrode as shown by X-ray diffraction. The tetragonal structure of the BTO films, which is a prerequisite for the piezoelectric effect, was identified by Raman spectroscopy. In the BTO film deposited at 5.10{sup −2} mbar strain was mostly localized inside the BTO grains whereas at 5.10{sup −3} mbar, it was localized at the grain boundaries. The BTO/SRO/YSZ layers were finally deposited on Si microcantilevers at an O{sub 2} pressure of 5.10{sup −3} mbar. The strain level was low enough to evaluate the BTO Young modulus. Transmission electron microscopy (TEM) was used to investigate the epitaxial quality of the layers and their epitaxial relationship on plain silicon wafers as well as on released microcantilevers, thanks to Focused-Ion-Beam TEM lamella preparation.

  14. Structural characterisation of BaTiO3 thin films deposited on SrRuO3/YSZ buffered silicon substrates and silicon microcantilevers

    International Nuclear Information System (INIS)

    We report on the progress towards an all epitaxial oxide layer technology on silicon substrates for epitaxial piezoelectric microelectromechanical systems. (101)-oriented epitaxial tetragonal BaTiO3 (BTO) thin films were deposited at two different oxygen pressures, 5.10−2 mbar and 5.10−3 mbar, on SrRuO3/Yttria-stabilized zirconia (YSZ) buffered silicon substrates by pulsed laser deposition. The YSZ layer full (001) orientation allowed the further growth of a fully (110)-oriented conductive SrRuO3 electrode as shown by X-ray diffraction. The tetragonal structure of the BTO films, which is a prerequisite for the piezoelectric effect, was identified by Raman spectroscopy. In the BTO film deposited at 5.10−2 mbar strain was mostly localized inside the BTO grains whereas at 5.10−3 mbar, it was localized at the grain boundaries. The BTO/SRO/YSZ layers were finally deposited on Si microcantilevers at an O2 pressure of 5.10−3 mbar. The strain level was low enough to evaluate the BTO Young modulus. Transmission electron microscopy (TEM) was used to investigate the epitaxial quality of the layers and their epitaxial relationship on plain silicon wafers as well as on released microcantilevers, thanks to Focused-Ion-Beam TEM lamella preparation

  15. Fabrication and characterization of ferroelectric PLZT film capacitors on metallic substrates.

    Energy Technology Data Exchange (ETDEWEB)

    Ma, B.; Narayanan, M.; Tong, S.; Balachandran, U.; Energy Systems

    2010-01-01

    We have grown ferroelectric Pb{sub 0.92}La{sub 0.08}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} (PLZT) films on Hastelloy C276 (HC) substrates by chemical solution deposition. Samples of 1.15-{micro}m-thick PLZT films were prepared on HC with and without lanthanum nickel oxide (LNO) films as an intermediate buffer layer. On samples with and without LNO buffers at room temperature, we measured dielectric constants of {approx}1,300 and {approx}450 and loss tangents of {approx}0.06 and {approx}0.07, respectively. For PLZT films grown on HC with LNO buffer, the dielectric constant increases, while the dielectric loss decreases, with increasing temperature. A dielectric constant of {approx}2,000 and loss of {approx}0.05 were observed at 150 C. Samples with LNO buffer also exhibited slimmer hysteresis loops and lower leakage current density when compared to samples without LNO buffer. The following results were measured on samples with and without LNO buffers: remanent polarization (P{sub r}) values of 21.3 and 36.4 {micro}C/cm{sup 2}, coercive electric field (E{sub c}) values of 41 and 173 kV/cm, and leakage current densities of {approx}1.1 x 10{sup -8} and {approx}1.6 x 10{sup -7} A/cm{sup 2}, respectively. The energy storage capability was measured at {approx}65 J/cm{sup 3} for the PLZT film-on-foil capacitor deposited on HC with LNO buffer.

  16. Enhanced Lifetime of Polymer Solar Cells by Surface Passivation of Metal Oxide Buffer Layers.

    Science.gov (United States)

    Venkatesan, Swaminathan; Ngo, Evan; Khatiwada, Devendra; Zhang, Cheng; Qiao, Qiquan

    2015-07-29

    The role of electron selective interfaces on the performance and lifetime of polymer solar cells were compared and analyzed. Bilayer interfaces consisting of metal oxide films with cationic polymer modification namely poly ethylenimine ethoxylated (PEIE) were found to enhance device lifetime compared to bare metal oxide films when used as an electron selective cathode interface. Devices utilizing surface-modified metal oxide layers showed enhanced lifetimes, retaining up to 85% of their original efficiency when stored in ambient atmosphere for 180 days without any encapsulation. The work function and surface potential of zinc oxide (ZnO) and ZnO/PEIE interlayers were evaluated using Kelvin probe and Kelvin probe force microscopy (KPFM) respectively. Kelvin probe measurements showed a smaller reduction in work function of ZnO/PEIE films compared to bare ZnO films when aged in atmospheric conditions. KPFM measurements showed that the surface potential of the ZnO surface drastically reduces when stored in ambient air for 7 days because of surface oxidation. Surface oxidation of the interface led to a substantial decrease in the performance in aged devices. The enhancement in the lifetime of devices with a bilayer interface was correlated to the suppressed surface oxidation of the metal oxide layers. The PEIE passivated surface retained a lower Fermi level when aged, which led to lower trap-assisted recombination at the polymer-cathode interface. Further photocharge extraction by linearly increasing voltage (Photo-CELIV) measurements were performed on fresh and aged samples to evaluate the field required to extract maximum charges. Fresh devices with a bare ZnO cathode interlayer required a lower field than devices with ZnO/PEIE cathode interface. However, aged devices with ZnO required a much higher field to extract charges while aged devices with ZnO/PEIE showed a minor increase compared to the fresh devices. Results indicate that surface modification can act as a

  17. Influence of the Substrate on the Formation of Metallic Glass Coatings by Cold Gas Spraying

    Science.gov (United States)

    Henao, John; Concustell, Amadeu; Dosta, Sergi; Cinca, Núria; Cano, Irene G.; Guilemany, Josep M.

    2016-06-01

    Cold gas spray technology has been used to build up coatings of Fe-base metallic glass onto different metallic substrates. In this work, the effect of the substrate properties on the viscoplastic response of metallic glass particles during their impact has been studied. Thick coatings with high deposition efficiencies have been built-up in conditions of homogeneous flow on substrates such as Mild Steel AISI 1040, Stainless Steel 316L, Inconel 625, Aluminum 7075-T6, and Copper (99.9%). Properties of the substrate have been identified to play an important role in the viscoplastic response of the metallic glass particles at impact. Depending on the process gas conditions, the impact morphologies show not only inhomogeneous deformation but also homogeneous plastic flow despite the high strain rates, 108 to 109 s-1, involved in the technique. Interestingly, homogenous deformation of metallic glass particles is promoted depending on the hardness and the thermal diffusivity of the substrate and it is not exclusively a function of the kinetic energy and the temperature of the particle at impact. Coating formation is discussed in terms of fundamentals of dynamics of undercooled liquids, viscoplastic flow mechanisms of metallic glasses, and substrate properties. The findings presented in this work have been used to build up a detailed scheme of the deposition mechanism of metallic glass coatings by the cold gas spraying technology.

  18. Investigation of localized necking in substrate-supported metal layers: comparison of bifurcation and imperfection analyses

    OpenAIRE

    Ben Bettaieb, Mohamed; ABED-MERAIM, Farid

    2015-01-01

    Localized necking is often considered as precursor to failure in metal components. In modern technologies, functional components (e.g., in flexible electronic devices) may be affected by this necking phenomenon, and to avoid the occurrence of strain localization, elastomer substrates are bonded to the metal layers. This paper proposes an investigation of the development of localized necking in both freestanding metal layers and elastomer/metal bilayers. Finite strain versions of both rigid–pl...

  19. Synthesis of organolanthanides by metal addition on insaturated substrates in ether and reactivity

    International Nuclear Information System (INIS)

    The aim of the study is the extension to rare earths of the synthesis, well known for alkaline or alkaline earth metals, by direct metal addition to insaturated substrates in ether and where the metal is directly bound to carbon. A definition of formation conditions and affinity rules is attempled, both with substrates (essentially aromatic hydrocarbons and ketones) and with metals: Yb, Sm, Ce, Nd and others. The nature of obtained products by reaction of electrophiles on synthetised organometallics, allows investigations specific reactivity and structure. Potential catalytic transformation of olefins is precised

  20. Intercalation of metals and silicon at the interface of epitaxial graphene and its substrates

    International Nuclear Information System (INIS)

    Intercalations of metals and silicon between epitaxial graphene and its substrates are reviewed. For metal intercalation, seven different metals have been successfully intercalated at the interface of graphene/Ru(0001) and form different intercalated structures. Meanwhile, graphene maintains its original high quality after the intercalation and shows features of weakened interaction with the substrate. For silicon intercalation, two systems, graphene on Ru(0001) and on Ir(111), have been investigated. In both cases, graphene preserves its high quality and regains its original superlative properties after the silicon intercalation. More importantly, we demonstrate that thicker silicon layers can be intercalated at the interface, which allows the atomic control of the distance between graphene and the metal substrates. These results show the great potential of the intercalation method as a non-damaging approach to decouple epitaxial graphene from its substrates and even form a dielectric layer for future electronic applications. (topical review - low-dimensional nanostructures and devices)

  1. Surface-Enhanced Raman Scattering Study on Graphene-Coated Metallic Nanostructure Substrates

    Science.gov (United States)

    Hao, Qingzhen; Wang, Bei; Bossard, Jeremy A.; Kiraly, Brian; Zeng, Yong; Chiang, I-Kao; Jensen, Lasse; Werner, Douglas H.; Huang, Tony Jun

    2014-01-01

    Graphene, which has a linear electronic band structure, is widely considered as a semimetal. In the present study, we combine graphene with conventional metallic surface-enhanced Raman scattering (SERS) substrates to achieve higher sensitivity of SERS detection. We synthesize high-quality, single-layer graphene sheets by chemical vapor deposition (CVD) and transfer them from copper foils to gold nanostructures, i.e., nanoparticle or nanohole arrays. SERS measurements are carried out on methylene blue (MB) molecules. The combined graphene nanostructure substrates show about threefold or ninefold enhancement in the Raman signal of MB, compared with the bare nanohole or nanoparticle substrates, respectively. The difference in the enhancement factors is explained by the different morphologies of graphene on the two substrates with the aid of numerical simulations. Our study indicates that applying graphene to SERS substrates can be an effective way to improve the sensitivity of conventional metallic SERS substrates. PMID:24772200

  2. Structural and electrical properties of Pb(Zr,Ti)O3 thin films on NiCr substrate modified by LaNiO3 and PbTiO3 buffer layers

    Science.gov (United States)

    He, Liang; Cheng, Jinrong; Meng, Zhongyan

    2004-12-01

    Ferroelectric Pb(Zr,Ti)O3 (PZT) thin films were deposited onto the NiCr (NC) substrate by using sol-gel techniques. LaNiO3 (LNO) and PbTiO3 (PT) buffer layers have been introduced to grow single-phase perovskite PZT thin films at the lower temperature of 550°C. The (110) preferred orientation of PZT thin films was favored using LNO and PT buffer layers. Dielectric constant and remnant polarization of PZT thin films on NC with a LNO buffer layer achieved ~ 430 and 13 μC/cm2 respectively. The ferroelectric P-E loops of PZT thin films were shifted towards the positive field by introducing LNO buffer layers. In addition, the coercive field and internal bias field increased with increasing the thickness of LNO layer.

  3. Laser assisted removal of fixed contamination from metallic substrate

    International Nuclear Information System (INIS)

    A single mode pulsed fiber laser was used to remove fixed contamination from stainless steel substrate by ablation. Samples were simulated by electro-deposition technique with 232U as the test contaminant. Laser power, repetition rate, laser beam scanning speed and number of passes were optimised to obtain the desired ablation depth in the substrate. Ablation depth varying between few microns to few hundreds of microns could be achieved through careful control of these processing parameters. The absence of any activity in laser treated samples provided experimental signature of the efficacy of the laser assisted removal of fixed contamination. (author)

  4. Chemical solution deposition (CSD) of CeO2 and La2Zr2O7 buffer layers on cube textured NiW substrates

    International Nuclear Information System (INIS)

    We present results of crack free layers of CeO2 and La2Zr2O7 deposited by means of CSD on cube textured Ni-4 at.% W substrates. EBSD-data show histograms with very good inplane- and out-of-plane textures and were used to simulate the critical current density in the YBCO layer. The surface roughness, a sensitive feature for good deposition results, was analyzed with a profilometer. In the CSD process we applied, the 2, 4-pentanedionates of the metal cations in glacial acetic acid and methanol served as starting substances

  5. Plasma-Spraying Ceramics Onto Smooth Metallic Substrates

    Science.gov (United States)

    Miller, Robert A.; Brindley, William J.; Rouge, Carl J.; Leissler, George

    1992-01-01

    In fabrication process, plasma-sprayed ceramic coats bonded strongly to smooth metallic surfaces. Principal use of such coats in protecting metal parts in hot-gas paths of advanced gas turbine engines. Process consists of application of initial thin layer of ceramic on smooth surface by low-pressure-plasma spraying followed by application of layer of conventional, low-thermal-conductivity atmospheric-pressure plasma-sprayed ceramic.

  6. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    International Nuclear Information System (INIS)

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  7. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    Science.gov (United States)

    Li, Peiyuan; Yang, Fang; Li, Xiangcheng; He, Chunling; Su, Wei; Chen, Jinhao; Huo, Lini; Chen, Rui; Lu, Chensheng; Liang, Lifang

    2013-09-01

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  8. Investigation of porous metallic substrates for plasma sprayed thin-film SOFC

    International Nuclear Information System (INIS)

    For plasma sprayed thin-film SOFCs porous metallic substrates were investigated regarding the required properties. The main essential properties are a sufficient electrical conductivity, a high temperature corrosion resistance and an adapted thermal expansion coefficient with respect to the other SOFC components. Proceeding from these requirements metallic materials such as a porous Cr-ODS alloy (Cr-5Fe-1Y2O3), a stainless steel plate (Fe-18Cr-12Ni-2Mo) and a Ni felt were tested. Additionally, to investigate the metallic substrates and their interaction with the layers of the cells completely plasma sprayed SOFCs were fabricated and electrochemically characterized. (author)

  9. Characterization of PZT thin films on metal substrates; Charakterisierung von PZT-Duennschichten auf Metallsubstraten

    Energy Technology Data Exchange (ETDEWEB)

    Dutschke, A.

    2008-02-02

    state due to strong stresses within the films. The magnitude of the lattice distortion is independent of the crystallite size and its extent is generally smaller for crystallites in Nd-doped films than for such in undoped films. After the detailed analysis of the development of the boundary layer between metal substrate and PZT-film, it is identified as a non-ferroelectric, dielectric buffer-layer containing crystalline NiO und NiCr{sub 2}O{sub 4}, different chromium oxides and Pb{sub 2}(CrO{sub 4})O between the PZT film and the conductive substrate significantly diminishing the resulting dielectric properties of the system. By applying a non-stoichiometric La{sub 0,75}Sr{sub 0,2}MnO{sub 3} (ULSM)-electrode below the PZT-film, a better electrical contact is achieved, the (001)-orientation in undoped films is enhanced and narrow P-E-hysteresis loops can be obtained. (orig.)

  10. Influence of major elements and geological substrate on heavy metal composition of river sediments

    OpenAIRE

    Cappuyns, Valérie; De Saedeleer, Valerie; De Cooman, Ward; Swennen, Rudy

    2009-01-01

    Organic matter and clay content are generally used as predicting variables for background values of heavy metals in soils and sediments. For example, in environmental legislation, a standardization of total concentrations of heavy metals and organic pollutants is performed based on the clay- and organic carbon content and pH(KCl) of soils and sediments. In the present study, the relationship between total concentrations of heavy metals, major elements, the location and/or geological substrate...

  11. Zr-based conversion coatings for multi-metal substrates

    OpenAIRE

    Cerezo Palacios, J.M.

    2015-01-01

    In this PhD work, a new surface treatment based on the application of Zr-based conversion coatings by immersion in a Cu containing Zr-based conversion solution was investigated as a replacement of the traditional phosphating process for the automotive industry. Nowadays most of the cars are made of a combination of different metals, therefore, one of the aims of this work is to study the formation mechanism of Zr-based conversion coatings on different metallic surfaces. Prior to the immersion...

  12. Structural study of ZnSe films grown on substrate with InxGa1-xAs and Al1-xGaxAs buffer layers: strain, relaxation and lattice parameter

    International Nuclear Information System (INIS)

    ZnSe layers of various thickness were grown on (001) GaAs substrates, using InxGa1-xAs or Al1-xGaxAs as buffer layers by molecular beam epitaxy and were studied by high-resolution x-ray diffraction. The principal structural characteristics of ZnSe layer and buffer layer were determined using several reflections, such as (004) and two pairs of coupled asymmetric reflections, namely (224), (-2-24) and (115) (-1-15). In order to evaluate their validity, the experimental data obtained from these reflections were handled by means of two known expressions found in the literature. We have found the relaxation process of ZnSe layers is well described by a geometrical model including the thermal strain and small strain due to work hardening. The relaxation process is faster for ZnSe grown on ternary buffer layers despite the fact that, some buffer layers are pseudomorphically grown to the substrate; therefore we conclude that not only the lattice mismatches have effect on the relaxation process but also the surface state of the buffer layer has an influence in this process. (author)

  13. Effect of noble metal buffer layers on superconducting YBa/sub 2/Cu/sub 3/O/sub 7/ thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chien, C.L.; Xiao, G.; Streitz, F.H.; Gavrin, A.; Cieplak, M.Z.

    1987-12-21

    Superconducting YBa/sub 2/Cu/sub 3/O/sub 7/ thin films have been prepared by using a magnetron sputtering system in the single-source mode. Samples deposited on (100) single-crystal MgO with and without a Au buffer layer all show high transition temperatures (82--87 K). The use of a Au buffer layer significantly improves the superconducting properties, particularly the Meissner effect and critical current density (3.3 x 10/sup 6/ A/cm/sup 2/ at T = 2 K and 3.5 x 10/sup 4/ A/cm/sup 2/ at T = 77 K). The Au films remain metallic after high-temperature annealing in an oxygen atmosphere. We propose to use Au buffer layers as current shunts to protect superconducting films and devices.

  14. An all chemical solution deposition approach for the growth of highly textured CeO2 cap layers on La2Zr2O7-buffered long lengths of biaxially textured Ni-W substrates for YBCO-coated conductors

    International Nuclear Information System (INIS)

    A reel-to-reel, dip coating process has been developed to continuously deposit epitaxial La2Zr2O7 (LZO) and CeO2 on 5 m long cube-textured {100} (001)Ni tapes. Recent results for La2Zr2O7 and CeO2 buffer layers deposited on long lengths of Ni substrate for the realization of YBa2Cu3O7-x (YBCO)-coated conductors are presented. The major achievement is the development of a new all chemical solution deposition (CSD) process leading to the formation of highly textured buffer layers at moderate annealing temperatures. Reproducible highly textured, dense and crack-free LZO buffer layers and CeO2 cap layers were obtained for annealing temperatures as low as 900 deg. C in a reducing atmosphere (Ar-5 at.%-H2). The thickness of the LZO buffer layers was determined to be (200 ± 10) nm per single coating; prepared cerium oxide layers showed a thickness of 60 nm ± 10 nm. Pulsed laser deposition (PLD) was used to grow YBCO films on these substrates. A Tc0 of T = 90.5 K and ΔTc = 1.4 K was obtained on PLD-YBCO/CSD-CeO2 /CSD-LZO/Ni-5 at.% W, which shows the outstanding features of this new buffer layer architecture processed by CSD. The large layer thickness combined with low annealing temperatures is the main advantage of this new process for low-cost buffer layer deposition on Ni-RABiTS (rolling-assisted biaxially textured substrates)

  15. Biaxially textured composite substrates

    Energy Technology Data Exchange (ETDEWEB)

    Groves, James R.; Foltyn, Stephen R.; Arendt, Paul N.

    2005-04-26

    An article including a substrate, a layer of a metal phosphate material such as an aluminum phosphate material upon the surface of the substrate, and a layer of an oriented cubic oxide material having a rock-salt-like structure upon the metal phosphate material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon a layer of a buffer material such as a SrTi.sub.x Ru.sub.1-x O.sub.3 layer.

  16. ZnO deposition on metal substrates: Relating fabrication, morphology, and wettability

    Science.gov (United States)

    Beaini, Sara S.; Kronawitter, Coleman X.; Carey, Van P.; Mao, Samuel S.

    2013-05-01

    It is not common practice to deposit thin films on metal substrates, especially copper, which is a common heat exchanger metal and practical engineering material known for its heat transfer properties. While single crystal substrates offer ideal surfaces with uniform structure for compatibility with oxide deposition, metallic surfaces needed for industrial applications exhibit non-idealities that complicate the fabrication of oxide nanostructure arrays. The following study explored different ZnO fabrication techniques to deposit a (super)hydrophobic thin film of ZnO on a metal substrate, specifically copper, in order to explore its feasibility as an enhanced condensing surface. ZnO was selected for its non-toxicity, ability to be made (super)hydrophobic with hierarchical roughness, and its photoinduced hydrophilicity characteristic, which could be utilized to pattern it to have both hydrophobic-hydrophilic regions. We investigated the variation of ZnO's morphology and wetting state, using SEMs and sessile drop contact angle measurements, as a function of different fabrication techniques: sputtering, pulsed laser deposition (PLD), electrodeposition and annealing Zn. We successfully fabricated (super)hydrophobic ZnO on a mirror finish, commercially available copper substrate using the scalable electrodeposition technique. PLD for ZnO deposition did not prove viable, as the ZnO samples on metal substrates were hydrophilic and the process does not lend itself to scalability. The annealed Zn sheets did not exhibit consistent wetting state results.

  17. Micro-scale metallization on flexible polyimide substrate by Cu electroplating using SU-8 photoresist mask

    International Nuclear Information System (INIS)

    Technologies for flexible electronics have been developed to make electronic or microelectromechanical (MEMS) devices on inexpensive and flexible organic substrates. In order to fabricate the interconnect lines between device elements or layers in flexible electronic devices, metallization on the flexible substrate is essential. In this case, the width and conductivity of metallization line are very important for minimizing the size of device. Therefore, the realization of metallization process with the scale of a few micrometers on the flexible substrate is required. In this work, micro-scale metallization lines of Cu were fabricated on the flexible substrate by electroplating using the patterned mask of a negative-tone SU-8 photoresist. Polyimide surface was treated by O2/Ar atmospheric plasma for the improvement in adhesion between Cr layer and polyimide and in situ sputter deposition of 100-nm-thick Cu seed layers on the sputter-deposited 50-nm-thick Cr adhesion layer was followed. SU-8 photoresist was spin-coated and patterned by photolithography. Electroplating of Cu line, removal of SU-8, and selective wet etch of Cr adhesion and Cu seed layers were carried out. Gap between the Cu lines was successfully filled by spin-coating of polyimide. Micro-scale Cu metal lines with gap filling on the polyimide substrate with a thickness of 6-12 μm and an aspect ratio of 1-3 were successfully fabricated

  18. Effect of interface wetting on flattening of freely fallen metal droplet onto flat substrate surface

    Science.gov (United States)

    Fukumoto, Masahiro; Nishioka, Eiji; Matsubara, Toshikazu

    2002-03-01

    A free-falling experiment was conducted as a simulation of a thermal spray process. The flattening behavior of the freely fallen metal droplet impinged onto a flat substrate surface was investigated in a fundamental way. The substrates were kept at various temperatures, and the substrates were coated with gold by physical vapor deposition (PVD) and were prepared in order to investigate the effect of wetting at the splat-substrate interface on the flattening behavior of the droplet. A falling atmosphere was created with atmospheric pressure of nitrogen to prevent the oxidation of the melted droplet. Experiments under low-pressure conditions also were conducted. The different types of splat morphology were recognized in experiments conducted under a nitrogen atmosphere with atmospheric pressure. The splat morphology on a substrate at room temperature was of the splash type, whereas that on a substrate at high temperature was of the disk type. The microstructure observed on a cross-section of the splat obtained on the substrate at room temperature was an isotropic coarse grain, whereas that on the substrate at high temperature was a fine columnar grain. The grain size changed transitionally with increasing substrate temperature. The temperature of the transition on the gold-coated substrate was higher than that on the naked substrate. The microstructure of the cross-section of the splat obtained under low pressure was finely columnar even on the substrate at room temperature. The results indicate that the metal droplet wets better under the low-pressure condition than under the atmospheric pressure nitrogen condition and that wetting has a significant role in the flattening of the droplet.

  19. Development of a four-zone carousel process packed with metal ion-imprinted polymer for continuous separation of copper ions from manganese ions, cobalt ions, and the constituent metal ions of the buffer solution used as eluent.

    Science.gov (United States)

    Jo, Se-Hee; Park, Chanhun; Yi, Sung Chul; Kim, Dukjoon; Mun, Sungyong

    2011-08-19

    A three-zone carousel process, in which Cu(II)-imprinted polymer (Cu-MIP) and a buffer solution were employed as adsorbent and eluent respectively, has been developed previously for continuous separation of Cu²⁺ (product) from Mn²⁺ and Co²⁺ (impurities). Although this process was reported to be successful in the aforementioned separation task, the way of using a buffer solution as eluent made it inevitable that the product stream included the buffer-related metal ions (i.e., the constituent metal ions of the buffer solution) as well as copper ions. For a more perfect recovery of copper ions, it would be necessary to improve the previous carousel process such that it can remove the buffer-related metal ions from copper ions while maintaining the previous function of separating copper ions from the other 2 impure heavy-metal ions. This improvement was made in this study by proposing a four-zone carousel process based on the following strategy: (1) the addition of one more zone for performing the two-step re-equilibration tasks and (2) the use of water as the eluent of the washing step in the separation zone. The operating conditions of such a proposed process were determined on the basis of the data from a series of single-column experiments. Under the determined operating conditions, 3 runs of carousel experiments were carried out. The results of these experiments revealed that the feed-loading time was a key parameter affecting the performance of the proposed process. Consequently, the continuous separation of copper ions from both the impure heavy-metal ions and the buffer-related metal ions could be achieved with a purity of 91.9% and a yield of 92.8% by using the proposed carousel process based on a properly chosen feed-loading time. PMID:21764065

  20. Direct metal transfer printing on flexible substrate for fabricating optics functional devices

    Science.gov (United States)

    Jiang, Yingjie; Zhou, Xiaohong; Zhang, Feng; Shi, Zhenwu; Chen, Linsen; Peng, Changsi

    2015-11-01

    New functional materials and devices based on metal patterns can be widely used in many new and expanding industries,such as flat panel displays, alternative energy,sensors and so on. In this paper, we introduce a new transfer printing method for fabricating metal optics functional devices. This method can directly transfer a metal pattern from a polyethylene terephthalate (PET)supported UV or polydimethylsiloxane (PDMS) pattern to another PET substrate. Purely taking advantage of the anaerobic UV curing adhesive (a-UV) on PET substrate, metal film can be easily peeled off from micro/nano-structured surface. As a result, metal film on the protrusion can be selectively transferred onto the target substrate, to make it the metal functional surface. But which on the bottom can not be transferred. This method provides low cost fabrication of metal thin film devices by avoiding high cost lithography process. Compared with conventional approach, this method can get more smooth rough edges and has wider tolerance range for the original master mold. Future developments and potential applications of this metal transfer method will be addressed.

  1. Removing paint from a metal substrate using a flattened top laser

    Institute of Scientific and Technical Information of China (English)

    Shi Shu-Dong; Li Wei; Du Peng; Wang Meng; Song Feng; Liu Shu-Jing; Chen Nian-Jiang; Zhao Hong; Yang Wen-Shi

    2012-01-01

    In this paper,we investigate laser cleaning using a flattened top laser to remove paint coating from a metal substrate.Under the irradiation of a flattened top laser,the coating paint of the metal substrate can be removed efficiently by laser induced ablation,stress,and displacement force.The temperature distribution,stress,and displacement are calculated in the coating layer and substrate using finite element analysis.The effects of a Gaussian laser and a flattened top laser and the results of different diameters of laser spot are compared.The investigation shows that the flattened top laser can reduce the substrate damage and enhance the cleaning efficiency.This method meets the need of large area industrial cleaning applications by optimizing the flattened top laser parameters.

  2. Enhanced Transmission and Second Harmonic Generation from Subwavelength Slits on Metal Substrates

    CERN Document Server

    Vincenti, M A; Petruzzelli, V; D'Orazio, A; Prudenzano, F; De Ceglia, D; Akozbekb, N; Bloemerb, M J; Ashley, P; Scalora, M

    2008-01-01

    We theoretically investigate second harmonic generation that originates from the nonlinear, magnetic Lorentz force term from single and multiple apertures carved on thick, opaque metal substrates. The linear transmission properties of apertures on metal substrates have been previously studied in the context of the extraordinary transmission of light. The transmission process is driven by a number of physical mechanisms, whose characteristics and relative importance depend on the thickness of the metallic substrate, slit size, and slit separation. In this work we show that a combination of cavity effects and surface plasmon generation gives rise to enhanced second harmonic generation in the regime of extraordinary transmittance of the pump field. We have studied both forward and backward second harmonic generation conversion efficiencies as functions of the geometrical parameters, and how they relate to pump transmission efficiency. The resonance phenomenon is evident in the generated second harmonic signal, a...

  3. Evaluation and Characterization of Plasma Sprayed Cu Slag-Al Composite Coatings on Metal Substrates

    OpenAIRE

    S. Mantry; Jha, B. B.; Satapathy, A.

    2013-01-01

    Copper slag is a waste product obtained during matte smelting and refining of copper. The present work explores the coating potential of copper slag by plasma spraying. This work shows that copper slag is eminently coatable. An attempt has been made in the present investigation to use the composites coatings of copper slag and Al powder in suitable combination on aluminium and mild steel substrates in order to improve the surface properties of these ductile metal-alloy substrates. When premix...

  4. Repairing Chipped Silicide Coatings on Refractory Metal Substrates

    Science.gov (United States)

    Youngquist, Robert

    2006-01-01

    The space shuttle orbiter s reaction control system (RCS) is a series of small thrusters that use hypergolic fuels to orient the orbiter in space. The RCS thrusters are constructed from a special niobium-based alloy -- the C-103. This alloy retains excellent mechanical properties from cryogenic temperature all the way up to 2,500 F (1,370 C). C-103 is susceptible to rapid oxidation at elevated temperatures. The authors have developed two methods to repair damaged R512a coatings on C-103. For the first repair technique, metal foundries, semiconductor manufacturers, and many other industries have developed and routinely use coatings that can easily be painted on metal to protect it from corrosion, including oxidation, to temperatures in excess of 2,500 F (1,370 C). This first repair technique is considered somewhat temporary. The second repair technique is based on using the native coating material of the RCS nozzles. the chipped area is ground out and a "green" R512a coating is applied to the repair area. Both repair techniques can be applied for moderate protection until the permanent laser-repair technique is available to the repair area.

  5. Reduction in edge dislocation density in corundum-structured α-Ga2O3 layers on sapphire substrates with quasi-graded α-(Al,Ga)2O3 buffer layers

    Science.gov (United States)

    Jinno, Riena; Uchida, Takayuki; Kaneko, Kentaro; Fujita, Shizuo

    2016-07-01

    Efforts have been made to reduce the density of defects in corundum-structured α-Ga2O3 thin films on sapphire substrates by applying quasi-graded α-(Al x Ga1‑ x )2O3 buffer layers. Transmission electron microscopy images revealed that most strains were located in the α-(Al x Ga1‑ x )2O3 buffer layers, and that the total density of dislocations in the α-Ga2O3 thin films was successfully decreased by more than one order of magnitude compared with that without buffer layers, that is, the screw and edge dislocation densities were about 3 × 108 and 6 × 108 cm‑2, respectively.

  6. Effects of AlN buffer layer thickness on the crystallinity and surface morphology of 10-µm-thick a-plane AlN films grown on r-plane sapphire substrates

    Science.gov (United States)

    Lin, Chia-Hung; Tamaki, Shinya; Yamashita, Yasuhiro; Miyake, Hideto; Hiramatsu, Kazumasa

    2016-08-01

    10-µm-thick a-plane AlN(11\\bar{2}0) films containing a low-temperature AlN (LT-AlN) buffer layer and a high-temperature AlN (HT-AlN) film were prepared on r-plane sapphire (1\\bar{1}02) substrates. The crystallinity of all the samples with different LT-AlN buffer layer thicknesses was improved after thermal annealing and HT-AlN growth, mainly owing to the elimination of domain boundaries and the concurrent suppression of facet formation. The optimum crystallinity of HT-AlN films was obtained with full widths at half maximum of the X-ray rocking curves of 660 arcsec for AlN(11\\bar{2}0)\\parallel [1\\bar{1}00]AlN and 840 arcsec for (0002) using a 200-nm-thick LT-AlN buffer layer.

  7. Electroless deposition of metal nanoparticles on graphene with substrate-assisted techniques

    Science.gov (United States)

    Zaniewski, Anna M.; Trimble, Christie J.; Meeks, Veronica; Nemanich, Robert J.

    2015-03-01

    We present the electroless reduction of solution-based metal ions for nanoparticle deposition on a variety of substrates. The substrates include graphene-coated metals, insulators, doped semiconductors, and patterned ferroelectrics. We find that the metal ions are spontaneously reduced on a wide variety of graphene substrates, and the substrates play a large role in the nanoparticle coverage. For example, the reduction of gold chloride to gold nanoparticles on graphene/lithium niobate results in 3% nanoparticle coverage compared to 20% coverage on graphene/silicon and 60% on graphene/copper. Given that the work function of graphene is approximately 4.4eV, the Fermi level is -0.1 V vs the normal hydrogen electrode (NHE). Since the reduction potential of gold chloride is +1.002 V, the spontaneous transfer of electrons from the graphene to the metal ion is energetically favorable. However, we find substrates with similar work functions nevertheless result in varied deposition rates, which we attribute to electron availability. We also find that patterned ferrolectrics can be used as a template for patterned nanoparticle deposition, with and without graphene. This work is supported by the National Science Foundation under Grant # DMR-1206935.

  8. Salt-Driven Deposition of Thermoresponsive Polymer-Coated Metal Nanoparticles on Solid Substrates.

    Science.gov (United States)

    Zhang, Zhiyue; Maji, Samarendra; da Fonseca Antunes, André B; De Rycke, Riet; Hoogenboom, Richard; De Geest, Bruno G

    2016-06-13

    Here we report on a simple, generally applicable method for depositing metal nanoparticles on a wide variety of solid surfaces under all aqueous conditions. Noble-metal nanoparticles obtained by citrate reduction followed by coating with thermoresponsive polymers spontaneously form a monolayer-like structure on a wide variety of substrates in presence of sodium chloride whereas this phenomenon does not occur in salt-free medium. Interestingly, this phenomenon occurs below the cloud point temperature of the polymers and we hypothesize that salt ion-induced screening of electrostatic charges on the nanoparticle surface entropically favors hydrophobic association between the polymer-coated nanoparticles and a hydrophobic substrate. PMID:27142455

  9. Characterization of NiC/Ti supermirror deposited on a metallic substrate

    International Nuclear Information System (INIS)

    Neutron guide tubes, which are installed near reactor cores, are damaged by neutrons and gamma rays irradiation. Those glass substrates which contain boron material are affected by (n, α) reaction, and ionization effect of gamma rays on material strength decrease duration of use of neutron guide tubes. In order to increase resistance to radiation, we have fabricated a supermirror with Ni-P metallic substrate. The substrate roughness with 0.3 - 0.4 nm (rms) was produced by superpolishing. The neutron reflectivity reached 76% for an m=3 supermirror. (author)

  10. Vacuum deposition of high quality metal films on porous substrates

    International Nuclear Information System (INIS)

    A composite mandrel has been developed consisting of a core of low density polymethylpentene foam overcoated with a thin layer of film-forming polymer. The surface tension and viscosity of the coating solution are important parameters in obtaining a polymer film which forms a continuous, smooth skin over the core without penetrating into the foam matrix. Water soluble film formers with surface tensions in the range of 45 dyn/cm and minimum viscosities of a few hundred centipoises have been found most satisfactory for coating polymethylpentene foam. By means of this technique, continuous polymer fims with thicknesses of 10--20 μm have been formed on the surface of machined polymethylpentene foam blanks. Aluminum has been vacuum deposited onto these composite mandrels to produce metal films which appear smooth and generally defect free even at 10 000 times magnification

  11. Incorporation of metal nanoparticles into wood substrate and methods

    Energy Technology Data Exchange (ETDEWEB)

    Rector, Kirk D; Lucas, Marcel

    2015-11-04

    Metal nanoparticles were incorporated into wood. Ionic liquids were used to expand the wood cell wall structure for nanoparticle incorporation into the cell wall structure. Nanoparticles of elemental gold or silver were found to be effective surface enhanced Raman spectroscopy (SERS) imaging contrast or sensing agents. Nanoparticles of elemental iron were found to be efficient microwave absorbers and caused localized heating for disrupting the integrity of the lignocellulosic matrix. Controls suggest that the localized heating around the iron nanoparticles reduces losses of cellulose in the form of water, volatiles and CO.sub.2. The ionic liquid is needed during the incorporation process at room temperature. The use of small amounts of ionic liquid combined with the absence of an ionic liquid purification step and a lower energy and water use are expected to reduce costs in an up-scaled pretreatment process.

  12. Highly textured oxypnictide superconducting thin films on metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Kazumasa, E-mail: iida@nuap.nagoya-u.ac.jp; Kurth, Fritz; Grinenko, Vadim; Hänisch, Jens [Institute for Metallic Materials, IFW Dresden, D-01171 Dresden (Germany); Chihara, Masashi; Sumiya, Naoki; Hatano, Takafumi; Ikuta, Hiroshi [Department of Crystalline Materials Science, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Ichinose, Ataru; Tsukada, Ichiro [Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196 (Japan); Matias, Vladimir [iBeam Materials, Inc., 2778A Agua Fria Street, Santa Fe, New Mexico 87507 (United States); Holzapfel, Bernhard [Institute for Technical Physics, Karlsruhe Institute of Technology, Hermann von Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)

    2014-10-27

    Highly textured NdFeAs(O,F) thin films have been grown on ion beam assisted deposition-MgO/Y{sub 2}O{sub 3}/Hastelloy substrates by molecular beam epitaxy. The oxypnictide coated conductors showed a superconducting transition temperature (T{sub c}) of 43 K with a self-field critical current density (J{sub c}) of 7.0×10{sup 4} A/cm{sup 2} at 5 K, more than 20 times higher than powder-in-tube processed SmFeAs(O,F) wires. Albeit higher T{sub c} as well as better crystalline quality than Co-doped BaFe{sub 2}As{sub 2} coated conductors, in-field J{sub c} of NdFeAs(O,F) was lower than that of Co-doped BaFe{sub 2}As{sub 2}. These results suggest that grain boundaries in oxypnictides reduce J{sub c} significantly compared to that in Co-doped BaFe{sub 2}As{sub 2} and, hence biaxial texture is necessary for high J{sub c.}.

  13. Enhancement of the lithium cycling capability using Li–Zn alloy substrate for lithium metal batteries

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Li-Zn alloy substrate is novelly formed by Li electrodeposition on the Zn substrate precursor. • The coulombic efficiency of Li deposition/stripping on the Li-Zn alloy substrate remains high at 96.7% after 400 cycles. • The SEI film formed during the formation of Li-Zn alloy is stable during Li deposition/stripping cycling on the Li-Zn substrate. • The exchange current density of Li deposition on the Li-Zn substrate is 9.21 × 10−4 A cm−2 which is nearly eight times larger than that on the Cu substrate. - Abstract: The cycling performance of a Li metal electrode in rechargeable Li batteries is studied using a novelly formed Li–Zn alloy as a substrate. A Zn layer electrodeposited on a Cu disk with ultrasonic assistance is used as a substrate precursor. Li electrodeposition followed to form the Li–Zn alloy. The morphologies of the substrate before and after Li deposition and stripping are investigated by scanning electron microscopy (SEM), and the electrochemical properties of the substrate are investigated by galvanostatic charge-discharge and cyclic voltammetry (CV). The growth states of solid electrolyte interface (SEI) films of Li deposits on the Li–Zn alloy and Cu surfaces are compared by electrochemical impedance spectroscopy (EIS); exchange current densities of Li electrodeposition on Cu, Zn, and Li–Zn alloy substrates are also compared based on tests of constant current pulse deposition. The efficiency of Li deposition/stripping on the Li–Zn alloy substrate remains high at 96.7% after 400 cycles at a current density of 0.1 mA cm−2 and 250 cycles at the current density of 0.2 mA cm−2. These results can be attributed to the formation of a stable SEI film on the Li–Zn substrate and the high exchange current density of Li deposition and stripping on this substrate. The Li–Zn alloy proposed in this work may be a perfect substrate for enhancing the cycling capability of Li metal electrode

  14. Effect of heavy metals on pH buffering capacity and solubility of Ca, Mg, K, and P in non-spiked and heavy metal-spiked soils.

    Science.gov (United States)

    Najafi, Sarvenaz; Jalali, Mohsen

    2016-06-01

    In many parts of the world, soil acidification and heavy metal contamination has become a serious concern due to the adverse effects on chemical properties of soil and crop yield. The aim of this study was to investigate the effect of pH (in the range of 1 to 3 units above and below the native pH of soils) on calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P) solubility in non-spiked and heavy metal-spiked soil samples. Spiked samples were prepared by cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) as chloride salts and incubating soils for 40 days. The pH buffering capacity (pHBC) of each sample was determined by plotting the amount of H(+) or OH(-) added (mmol kg(-1)) versus the related pH value. The pHBC of soils ranged from 47.1 to 1302.5 mmol kg(-1) for non-spiked samples and from 45.0 to 1187.4 mmol kg(-1) for spiked soil samples. The pHBC values were higher in soil 2 (non-spiked and spiked) which had higher calcium carbonate content. The results indicated the presence of heavy metals in soils generally decreased the solution pH and pHBC values in spiked samples. In general, solubility of Ca, Mg, and K decreased with increasing equilibrium pH of non-spiked and spiked soil samples. In the case of P, increasing the pH to about 7, decreased the solubility in all soils but further increase of pH from 7, enhanced P solubility. The solubility trends and values for Ca, Mg, and K did not differed significantly in non-spiked and spiked samples. But in the case of P, a reduction in solubility was observed in heavy metal-spiked soils. The information obtained in this study can be useful to make better estimation of the effects of soil pollutants on anion and cation solubility from agricultural and environmental viewpoints. PMID:27168329

  15. Epitaxial growth of YBa2Cu3O7−x films on Ce0.9La0.1O2−y buffered yttria-stabilized zirconia substrates by an all-chemical-solution route

    DEFF Research Database (Denmark)

    Yue, Zhao; Wu, Wei; Tang, Xiao;

    2014-01-01

    In view of high rate fabrication of coated conductors at low-cost, YBa2Cu3O7 (YBCO) films on Ce0.9La0.1O2−y buffered yttria-stabilized zirconia substrates were deposited by means of a novel low-fluorine metal–organic solution route. A high critical current density of 3 MA cm−2 (77 K, self field...

  16. Enhancement of multiferroic properties of Pb(Fe1/2Nb1/2)O-3 thin films on SrRuO3 buffered SrTiO3 substrates

    OpenAIRE

    Yan, Li; Zhao, X.; Li, Jiefang; Viehland, Dwight D.

    2009-01-01

    We report multiferroic properties of Pb(Fe1/2Nb1/2)O-3 (or PFN) epitaxial thin layers grown on (001), (110), and (111) SrTiO3 substrates with and without a SrRuO3 (SRO) buffer. Our findings are as follows: (i) the constraint stress on (001) substrates is more than ten times larger than those on (110) and (111); (ii) this large constraint stress induces higher piezoelectric constants, magnetic permeability and magnetization for (001) PFN compared with (110) and (111) layers; (iii) epitaxy dist...

  17. Growth of c-plane ZnO on γ-LiAlO2 (1 0 0) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy

    International Nuclear Information System (INIS)

    Highlights: • ZnO epilayers were grown on LiAlO2 (1 0 0) substrate with a GaN buffer layer by MBE. • A high Zn/O flux ratio is beneficial for reducing the density of screw dislocations. • Reciprocal space maps demonstrate that the misfit strain in ZnO has been relaxed. • No interfacial layer is formed at ZnO/GaN interface using a Zn pre-exposure strategy. - Abstract: C-plane ZnO epilayers were grown on LiAlO2 (1 0 0) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy. Both the X-ray rocking curves and the transmission electron microscopy analyses indicate that the ZnO epilayers exhibit a lower threading dislocation density (∼1 × 1010 cm−2) as compared to those grown on LiAlO2 substrate without the buffer layer. A high Zn/O flux ratio is beneficial for reducing the density of screw-type dislocations. Reciprocal space maps demonstrate that the misfit strain has been relaxed. No interfacial layer is formed at the ZnO/GaN interface by using a Zn pre-exposure strategy. The ZnO epilayers exhibit a strong near band edge emission at 3.28 eV at room temperature with a negligible green band emission

  18. Growth of c-plane ZnO on γ-LiAlO{sub 2} (1 0 0) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Yan, T. [Department of Materials and Optoelectronic Science/Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China); Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002 (China); Lu, C.-Y.J. [Department of Materials and Optoelectronic Science/Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China); Schuber, R. [Institute of Applied Physics/DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, DE-76131 Karlsruhe (Germany); Chang, L., E-mail: lwchang@mail.nsysu.edu.tw [Department of Materials and Optoelectronic Science/Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China); Schaadt, D.M. [Institute of Applied Physics/DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, DE-76131 Karlsruhe (Germany); Institute of Energy Research and Phyiscal Technologies, Clausthal Technical University, Am Stollen 19B, D-38640 Goslar (Germany); Chou, M.M.C.; Ploog, K.H. [Department of Materials and Optoelectronic Science/Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China); Chiang, C.-M. [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC (China)

    2015-10-01

    Highlights: • ZnO epilayers were grown on LiAlO{sub 2} (1 0 0) substrate with a GaN buffer layer by MBE. • A high Zn/O flux ratio is beneficial for reducing the density of screw dislocations. • Reciprocal space maps demonstrate that the misfit strain in ZnO has been relaxed. • No interfacial layer is formed at ZnO/GaN interface using a Zn pre-exposure strategy. - Abstract: C-plane ZnO epilayers were grown on LiAlO{sub 2} (1 0 0) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy. Both the X-ray rocking curves and the transmission electron microscopy analyses indicate that the ZnO epilayers exhibit a lower threading dislocation density (∼1 × 10{sup 10} cm{sup −2}) as compared to those grown on LiAlO{sub 2} substrate without the buffer layer. A high Zn/O flux ratio is beneficial for reducing the density of screw-type dislocations. Reciprocal space maps demonstrate that the misfit strain has been relaxed. No interfacial layer is formed at the ZnO/GaN interface by using a Zn pre-exposure strategy. The ZnO epilayers exhibit a strong near band edge emission at 3.28 eV at room temperature with a negligible green band emission.

  19. Preparation of C-axis textured LiNbO3 thin films on SiO2/Si substrates with a ZnO buffer layer by pulsed laser deposition process

    International Nuclear Information System (INIS)

    Highly C-axis textured LiNbO3 thin films were grown on SiO2/Si substrates with a ZnO buffer layer by XeCl excimer pulsed laser deposition technique. We fixed the target-substrate spacing at 40 mm, oxygen flow rate of 20 sccm and the repetition rate of 5 Hz, and then changed the substrate temperature, energy density and oxygen pressure to obtain the optimum deposition conditions. The effect of post-annealing process on improving the structural properties of the as-deposited LiNbO3 thin films was also studied. The ZnO buffer layers and LiNbO3 films were characterized by X-ray diffraction (XRD), atomic force microscopy and scanning electron microscopy to analyze their crystalline structure, surface roughness and surface morphology, respectively. For the optimum deposition parameters such as substrate temperature of 700 deg. C, energy density of 4.6 J/cm2 and oxygen pressure of 150 Pa, the full width at half maximum intensity (FWHM) of LiNbO3(0 0 6) peak was 0.22 deg. The FWHM of LiNbO3(0 0 6) peak was further reduced to 0.19 deg. via. in-situ post-treatment at 750 deg. C for 30 min. The results could be useful for integrating the surface acoustic wave device, optical waveguide and semiconductor device on the same Si substrate.

  20. Thin film pc-Si by aluminium induced crystallization on metallic substrate

    Science.gov (United States)

    Delachat, F.; Antoni, F.; Prathap, P.; Slaoui, A.; Cayron, C.; Ducros, C.

    2013-04-01

    Thin film polycrystalline silicon (pc-Si) on flexible metallic substrates is promising for low cost production of photovoltaic solar cells. One of the attractive methods to produce pc-Si solar cells consists in thickening a large-grained seed layer by epitaxy. In this work, the deposited seed layer is made by aluminium induced crystallization (AIC) of an amorphous silicon (a-Si) thin film on metallic substrates (Ni/Fe alloy) initially coated with a tantalum nitride (TaN) conductive diffusion barrier layer. Effect of the thermal budget on the AIC grown pc-Si seed layer was investigated in order to optimize the process (i.e. the quality of the pc-Si thin film). Structural and optical characterizations were carried out using optical microscopy, μ-Raman and Electron Backscatter Diffraction (EBSD). At optimal thermal annealing conditions, the continuous AIC grown pc-Si thin film showed an average grain size around 15 μm. The grains were preferably (001) oriented which is favorable for its epitaxial thickening. This work proves the feasibility of the AIC method to grow large grains pc-Si seed layer on TaN coated metal substrates. These results are, in terms of grains size, the finest obtained by AIC on metallic substrates.

  1. Thin film pc-Si by aluminium induced crystallization on metallic substrate

    Directory of Open Access Journals (Sweden)

    Cayron C.

    2013-04-01

    Full Text Available Thin film polycrystalline silicon (pc-Si on flexible metallic substrates is promising for low cost production of photovoltaic solar cells. One of the attractive methods to produce pc-Si solar cells consists in thickening a large-grained seed layer by epitaxy. In this work, the deposited seed layer is made by aluminium induced crystallization (AIC of an amorphous silicon (a-Si thin film on metallic substrates (Ni/Fe alloy initially coated with a tantalum nitride (TaN conductive diffusion barrier layer. Effect of the thermal budget on the AIC grown pc-Si seed layer was investigated in order to optimize the process (i.e. the quality of the pc-Si thin film. Structural and optical characterizations were carried out using optical microscopy, μ-Raman and Electron Backscatter Diffraction (EBSD. At optimal thermal annealing conditions, the continuous AIC grown pc-Si thin film showed an average grain size around 15 μm. The grains were preferably (001 oriented which is favorable for its epitaxial thickening. This work proves the feasibility of the AIC method to grow large grains pc-Si seed layer on TaN coated metal substrates. These results are, in terms of grains size, the finest obtained by AIC on metallic substrates.

  2. Physical masking process for integrating micro metallic structures on polymer substrate

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Hansen, Hans Nørgaard

    2009-01-01

    current study shows a novel approach for fabricating thin micro metallic structures on polymer substrates using a simple physical mask and a PVD equipment. The new process involves fewer process steps, it is cost effective and suitable for high volume industrial production. Current study suggests that...

  3. Design and synthesis of thin palladium membranes on porous metal substrate for hydrogen extraction

    Science.gov (United States)

    Shi, Z.; Szpunar, J. A.; Wu, S.

    2009-05-01

    Membrane separation is regarded nowadays as a preferred method for production of purified hydrogen. Palladium (Pd) is an attractive membrane material due to its ability to dissociate molecular hydrogen into atoms. It is usually deposited on the porous substrate that can provide good mechanical support and reduce the thickness of the membrane for maximizing hydrogen permeability. Pd membrane used for hydrogen separation must be thin enough to increase hydrogen flux and reduce cost while remaining thick enough to retain adhesion, attrition resistance and mechanical integrity during high temperature cycles. In this paper, the progress of electroless deposition of Pd around the pore area at surface of porous stainless steel was recorded and a bridge structure that was formed during the membrane deposition around the pore area of the substrate was illustrated. After that, the porous substrate was modified using micro-or nano-size metal or metal oxide particles in order to reduce pore size in the substrate surface. The experimental results obtained from hydrogen permeation through the Pd membranes having the thickness from 400 nm to 18 μm built on both modified and original porous stainless steel substrates demonstrate that these thin membranes are solid and they can be used at the temperature of 550°C and hydrogen pressure difference of 3.447x105 Pa. The proposed processing will allow optimizing the design and fabrication of thin Pd membranes on different porous substrates for hydrogen separation.

  4. Design and synthesis of thin palladium membranes on porous metal substrate for hydrogen extraction

    International Nuclear Information System (INIS)

    Membrane separation is regarded nowadays as a preferred method for production of purified hydrogen. Palladium (Pd) is an attractive membrane material due to its ability to dissociate molecular hydrogen into atoms. It is usually deposited on the porous substrate that can provide good mechanical support and reduce the thickness of the membrane for maximizing hydrogen permeability. Pd membrane used for hydrogen separation must be thin enough to increase hydrogen flux and reduce cost while remaining thick enough to retain adhesion, attrition resistance and mechanical integrity during high temperature cycles. In this paper, the progress of electroless deposition of Pd around the pore area at surface of porous stainless steel was recorded and a bridge structure that was formed during the membrane deposition around the pore area of the substrate was illustrated. After that, the porous substrate was modified using micro-or nano-size metal or metal oxide particles in order to reduce pore size in the substrate surface. The experimental results obtained from hydrogen permeation through the Pd membranes having the thickness from 400 nm to 18 μm built on both modified and original porous stainless steel substrates demonstrate that these thin membranes are solid and they can be used at the temperature of 550 deg. C and hydrogen pressure difference of 3.447x105 Pa. The proposed processing will allow optimizing the design and fabrication of thin Pd membranes on different porous substrates for hydrogen separation.

  5. Microplasmas for direct, substrate-independent deposition of nanostructured metal oxides

    Science.gov (United States)

    Mackie, Katherine E.; Pebley, Andrew C.; Butala, Megan M.; Zhang, Jinping; Stucky, Galen D.; Gordon, Michael J.

    2016-07-01

    A general, substrate-independent method for plasma deposition of nanostructured, crystalline metal oxides is presented. The technique uses a flow-through, micro-hollow cathode plasma discharge (supersonic microplasma jet) with a "remote" ring anode to deliver a highly directed flux of growth species to the substrate. A diverse range of nanostructured materials (e.g., CuO, α-Fe2O3, and NiO) can be deposited on any room temperature surface, e.g., conductors, insulators, plastics, fibers, and patterned surfaces, in a conformal fashion. The effects of deposition conditions, substrate type, and patterning on film morphology, nanostructure, and surface coverage are highlighted. The synthesis approach presented herein provides a general and tunable method to deposit a variety of functional and hierarchical metal oxide materials on many different surfaces. High surface area, conversion-type CuO electrodes for Li-ion batteries are demonstrated as a proof-of-concept example.

  6. Determination of interfacial adhesion strength between oxide scale and substrate for metallic SOFC interconnects

    Science.gov (United States)

    Sun, X.; Liu, W. N.; Stephens, E.; Khaleel, M. A.

    The interfacial adhesion strength between the oxide scale and the substrate is crucial to the reliability and durability of metallic interconnects in solid oxide fuel cell (SOFC) operating environments. It is necessary, therefore, to establish a methodology to quantify the interfacial adhesion strength between the oxide scale and the metallic interconnect substrate, and furthermore to design and optimize the interconnect material as well as the coating materials to meet the design life of an SOFC system. In this paper, we present an integrated experimental/analytical methodology for quantifying the interfacial adhesion strength between the oxide scale and a ferritic stainless steel interconnect. Stair-stepping indentation tests are used in conjunction with subsequent finite element analyses to predict the interfacial strength between the oxide scale and Crofer 22 APU substrate.

  7. Self-heating technique of metallic substrate for reel-to-reel and double-sided deposition of YBa2Cu3O7- δ films

    Science.gov (United States)

    Zhang, Fei; Zhao, Ruipeng; Xue, Yan; Wang, Hui; He, Yuanying; Zhang, Pan; Tao, Bowan; Xiong, Jie; Li, Yanrong

    2016-02-01

    A new, simple, and highly efficient heating technology for metal tape substrates is proposed and applied to reel-to-reel and double-sided film deposition. In this technology, direct electrical current ( I DC) is conducted into the metal layer of oxide-buffered metal substrate to induce heat. Different substrate surface temperatures were achieved by varying I DC from 22 to 25 A. At these temperatures, a series of 1-μm-thick and 5-cm-long YBa2Cu3O7- δ (YBCO) films were fabricated on ion-beam-assisted deposition (IBAD) templates through metal organic chemical vapor deposition. X-ray diffraction analysis on the samples revealed that the YBCO film changed its growth mode from mixed a-axis and c-axis to purely c-axis with increasing I DC. The optimal out-of-plane and in-plane texture reached ~1.4° and 3.5°, respectively. A 30-m-long and 500-nm-thick single-sided YBCO-coated conductor was also prepared through reel-to-reel deposition using the proposed heating method. The fabricated conductor presented homogeneous crystallization and texture and exhibited a critical current density at self-field and 77 K ( J c 77K, 0T ) of 2.8-3.2 MA/cm2. Moreover, 500-nm-thick YBCO films were fabricated simultaneously on both sides of the double-sided IBAD template. The two sides of films demonstrated uniform texture and J c 77K, 0T of 3.2 MA/cm2. Results demonstrated that the proposed substrate heating technology can be used for reel-to-reel and double-sided deposition of YBCO-coated conductors.

  8. Spinel-structured metal oxide on a substrate and method of making same by molecular beam epitaxy

    Science.gov (United States)

    Chambers, Scott A.

    2006-02-21

    A method of making a spinel-structured metal oxide on a substrate by molecular beam epitaxy, comprising the step of supplying activated oxygen, a first metal atom flux, and at least one other metal atom flux to the surface of the substrate, wherein the metal atom fluxes are individually controlled at the substrate so as to grow the spinel-structured metal oxide on the substrate and the metal oxide is substantially in a thermodynamically stable state during the growth of the metal oxide. A particular embodiment of the present invention encompasses a method of making a spinel-structured binary ferrite, including Co ferrite, without the need of a post-growth anneal to obtain the desired equilibrium state.

  9. Low-Temperature in Situ Growth of Graphene on Metallic Substrates and Its Application in Anticorrosion.

    Science.gov (United States)

    Zhu, Minmin; Du, Zehui; Yin, Zongyou; Zhou, Wenwen; Liu, Zhengdong; Tsang, Siu Hon; Teo, Edwin Hang Tong

    2016-01-13

    Metal or alloy corrosion brings about huge economic cost annually, which is becoming one area of growing concern in various industries, being in bulk state or nanoscale range. Here, single layer or few layers of graphene are deposited on various metallic substrates directly at a low temperature down to 400 °C. These substrates can be varied from hundreds-micrometer bulk metallic or alloy foils to tens of nanometer nanofibers (NFs). Corrosion analysis reveals that both graphene-grown steel sheets and NFs have reduced the corrosion rate of up to ten times lower than that of their bare corresponding counterparts. Moreover, such low-temperature in situ growth of graphene demonstrates stable and long-lasting anticorrosion after long-term immersion. This new class of graphene coated nanomaterials shows high potentials in anticorrosion applications for submarines, oil tankers/pipelines, and ruggedized electronics. PMID:26683895

  10. Novel Pretreatment of Hard Metal Substrate for Better Performance of Diamond Coated Cutting Tools

    Institute of Scientific and Technical Information of China (English)

    LU Fan-xiu; TANG Wei-zhong; MIAO Jin-qi; HE Li-fu; LI Cheng-ming; CHEN Guang-chao

    2004-01-01

    A surface engineering approach for a novel pre-treatment of hard metal tool substrate for optimum adhesion of diamond coatings is presented. Firstly, an alkaline solution was used to etch the WC grains to generate a rough surface for better mechanical interlocking. Subsequently, surface Co was removed by etching in acid solution. Then the hard metal substrate was boronized to form a compound interlayer which acted as an efficient diffusion barrier to prevent the outward diffusion of Co. Novel nano-microcrystalline composite diamond film coatings with a very smooth surface was deposited on the surface engineering pre-treated hard metal surface. Promising results of measurement in adhesion strength as well as field cutting tests have been obtained.

  11. Development of a large plano-elliptical neutron-focusing supermirror with metallic substrates.

    Science.gov (United States)

    Takeda, Shin; Yamagata, Yutaka; Yamada, Norifumi L; Hino, Masahiro; Hosobata, Takuya; Guo, Jiang; Morita, Shin-Ya; Oda, Tatsuro; Furusaka, Michihiro

    2016-06-13

    Results of this study demonstrated that electroless nickel-phosphorus (NiP) plated metal substrate is an excellent material for producing large aspherical neutron-focusing supermirrors. A large plano-elliptical neutron-focusing supermirror comprising two metallic segments was fabricated using single-point diamond cutting, precision polishing and supermirror coating. The average surface roughness of the metallic substrates was approximately 0.3 nm rms. For evaluation, the focusing supermirror was installed at the SOFIA neutron reflectometer, showing high neutron reflectivity and giving minimal beam width of 0.34 mm in FWHM. Because of the large beam divergence accepted by the mirror, the count rate with the focusing mirror was 3.3 times higher than that obtained using conventional two-slit collimation. PMID:27410268

  12. Malic enzyme: Tritium isotope effects with alternative dinucleotide substrates and divalent metal ions

    International Nuclear Information System (INIS)

    The NAD-malic enzyme from Ascaris suum catalyzes the divalent metal ion dependent oxidative decarboxylation of L-malate to yield pyruvate, carbon dioxide and NADH. Multiple isotope effect studies suggest a stepwise chemical mechanism with hydride transfer from L-malate to NAD occurring first to form oxalacetate, followed by decarboxylation. Utilizing L-malate-2-T, tritium V/K isotope effects have been determined for the hydride transfer step using a variety of alternative dinucleotide substrates and divalent metal ions. Combination of these data with deuterium isotope effects data and previously determined 13C isotope effects has allowed the calculation of intrinsic isotope effects for the malic enzyme catalyzed reaction. The identity of both the dinucleotide substrate and divalent metal ion has an effect of the size of the intrinsic isotope effect for hydride transfer

  13. Malic enzyme: Tritium isotope effects with alternative dinucleotide substrates and divalent metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Karsten, W.E.; Harris, B.G.; Cook, P.F. (Texas College of Osteopathic Medicine, Fort Worth (United States))

    1992-01-01

    The NAD-malic enzyme from Ascaris suum catalyzes the divalent metal ion dependent oxidative decarboxylation of L-malate to yield pyruvate, carbon dioxide and NADH. Multiple isotope effect studies suggest a stepwise chemical mechanism with hydride transfer from L-malate to NAD occurring first to form oxalacetate, followed by decarboxylation. Utilizing L-malate-2-T, tritium V/K isotope effects have been determined for the hydride transfer step using a variety of alternative dinucleotide substrates and divalent metal ions. Combination of these data with deuterium isotope effects data and previously determined [sup 13]C isotope effects has allowed the calculation of intrinsic isotope effects for the malic enzyme catalyzed reaction. The identity of both the dinucleotide substrate and divalent metal ion has an effect of the size of the intrinsic isotope effect for hydride transfer.

  14. Calcium and Zinc Containing Bactericidal Glass Coatings for Biomedical Metallic Substrates

    Directory of Open Access Journals (Sweden)

    Leticia Esteban-Tejeda

    2014-07-01

    Full Text Available The present work presents new bactericidal coatings, based on two families of non-toxic, antimicrobial glasses belonging to B2O3–SiO2–Na2O–ZnO and SiO2–Na2O–Al2O3–CaO–B2O3 systems. Free of cracking, single layer direct coatings on different biomedical metallic substrates (titanium alloy, Nb, Ta, and stainless steel have been developed. Thermal expansion mismatch was adjusted by changing glass composition of the glass type, as well as the firing atmosphere (air or Ar according to the biomedical metallic substrates. Formation of bubbles in some of the glassy coatings has been rationalized considering the reactions that take place at the different metal/coating interfaces. All the obtained coatings were proven to be strongly antibacterial versus Escherichia coli (>4 log.

  15. Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

    Directory of Open Access Journals (Sweden)

    Tyagi Renu

    2009-01-01

    Full Text Available Abstract Self-assembled InAs quantum dots (QDs were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs. The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.

  16. Perpendicularly magnetized (001)-textured D0{sub 22} MnGa films grown on an (Mg{sub 0.2}Ti{sub 0.8})O buffer with thermally oxidized Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hwachol; Sukegawa, Hiroaki, E-mail: sukegawa.hiroaki@nims.go.jp [National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba 305-0047 (Japan); Liu, Jun; Mitani, Seiji; Hono, Kazuhiro [National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8577 (Japan)

    2015-10-28

    We report the growth of (001)-textured polycrystalline D0{sub 22} MnGa films with perpendicular magnetic anisotropy (PMA) on thermally oxidized Si substrates using an (Mg{sub 0.2}Ti{sub 0.8})O (MTO) buffer layer. The ordered D0{sub 22} MnGa film grown at the optimum substrate temperature of 530 °C on the MTO buffer layer shows PMA with magnetization of 80 kA/m, PMA energy density of 0.28 MJ/m{sup 3}, and coercivity of 2.3 T. The scanning transmission electron microscope analysis confirms the formation of a highly (001)-textured structure and the elementally sharp interfaces between the MTO layer and the MnGa layer. The achieved D0{sub 22} MnGa PMA films on an amorphous substrate will provide the possible pathway of integration of a Mn-based PMA film into Si-based substrates.

  17. Microstructure of planar glass substrates modified by Laser Ablation Backwriting (LAB) of metal targets

    International Nuclear Information System (INIS)

    Geometrically controlled, channel-like structures were prepared on commercial, soda-lime glass substrates, by a Laser Ablation Backwriting (LAB) process using a commercial Nd:YVO4 laser fitted with a beam steering galvanometer mirror unit. 70Cu30Zn Brass alloy, Ag and Al metal targets were evaporated onto glass substrates by simple irradiation through the same glass substrates. The resultant structures were characterized by SEM, TEM, and UV-vis-nIR spectroscopy. These revealed the presence of metal nanostructures in the case of brass and Ag targets, with their typical local surface plasmon resonance (LSPR) bands. In contrast, Al was not found in its elemental form, but rather integrated into the glass substrate. These results were confirmed by energy dispersive X-ray microanalysis (EDS) studies, performed with TEM and SEM observation on representative, polished cross section samples. Preliminary light guiding studies demonstrated the potential to develop burried waveguides just below the surface of the glass substrates in all cases, suggesting that LAB may be a convenient method to prepare stable waveguides by modifying inexpensive, commercial window glass.

  18. Improved textured La2Zr2O7 buffer layers on bi-axially textured Ni–W substrates using CeO2 seed layers for YBa2Cu3O7−x coated conductors

    International Nuclear Information System (INIS)

    La2Zr2O7 (LZO) buffer layers were deposited on bi-axially textured Ni–W substrates with CeO2 seed layer by radio-frequency magnetron sputtering for the large-scale application of YBa2Cu3O7−x (YBCO) coated conductors. The microstructure and surface morphology of LZO buffer layers were studied by X-ray diffraction, optical microscopy, field emission scanning electron microscopy and atomic force microscopy. The influences of substrate temperature and oxygen partial pressure on the microstructure and surface morphology of LZO buffer layers were discussed. It was found that epitaxial LZO films were preferentially c-axis oriented without microcracks, with no degradation of crystallographic texture and with high surface crystallinity. Crack-free and strong c-axis aligned LZO films with no random orientation were obtained at relatively low substrate temperatures of 600–800 °C and in flowing 40 Pa gas mixtures of Ar–O2 with an effective oxygen partial pressure of 0.1–20 Pa. In addition, LZO films grown in low oxygen partial pressure have a smoother surface than films in higher oxygen partial pressure. Then, we fabricated YBCO coated conductors on the high-quality LZO buffer layers by pulsed laser deposition. The critical current density Jc = 2.25 MA/cm2 and critical current Ic = 180 A/cm of 0.8-μm-thick YBCO film at 77 K, self field were obtained. The magnetic field and angular dependences of critical current per width were discussed. Highly textured LZO films grown on CeO2 seed layer were suitable as a buffer layer for the growth of YBCO coated conductors with high currents. - Highlights: • La2Zr2O7 (LZO) films were firstly fabricated by magnetron sputtering. • We firstly used the buffer architecture LZO/CeO2 (seed). • We firstly fabricated YBa2Cu3O7+x films directly on LZO films

  19. Sub-surface alloying largely influences graphene nucleation and growth over transition metal substrates.

    Science.gov (United States)

    Zhang, Liying; Zhao, Xingju; Xue, Xinlian; Shi, Jinlei; Li, Chong; Ren, Xiaoyan; Niu, Chunyao; Jia, Yu; Guo, Zhengxiao; Li, Shunfang

    2015-11-11

    Sub-surface alloying (SSA) can be an effective approach to tuning surface functionalities. Focusing on Rh(111) as a typical substrate for graphene nucleation, we show strong modulation by SSA atoms of both the energetics and kinetics of graphene nucleation simulated by first-principles calculations. Counter-intuitively, when the sub-surface atoms are replaced by more active solute metal elements to the left of Rh in the periodic table, such as the early transition metals (TMs), Ru and Tc, the binding between a C atom and the substrate is weakened and two C atoms favor dimerization. Alternatively, when the alloying elements are the late TMs to the right of Rh, such as the relatively inert Pd and Ag, the repulsion between the two C atoms is enhanced. Such distinct results can be well addressed by the delicately modulated activities of the surface host atoms in the framework of the d-band theory. More specifically, we establish a very simple selection rule for optimizing the metal substrate for high quality graphene growth: the introduction of an early (late) solute TM in the SSA lowers (raises) the d-band center and the activity of the top-most host metal atoms, weakening (strengthening) the C-substrate binding, meanwhile both energetically and kinetically facilitating (hindering) the graphene nucleation, and simultaneously promoting (suppressing) the orientation disordering the graphene domains. Importantly, our preliminary theoretical results also show that such a simple rule is also proposed to be operative for graphene growth on the widely invoked Cu(111) catalytic substrate. PMID:26257125

  20. Fabrication and Characterisation of Rutile-TiO2 Coatings on Metallic Alloy Substrates

    Institute of Scientific and Technical Information of China (English)

    Y.Sun,D; D.SivaRamaKrishna

    2004-01-01

    In the present work, attempts have been made to extend the use of the tribological and chemical properties of rutile-TiO2 to metallic alloy systems, by forming a rutile coating on the metallic substrates. Two metallic alloys were selected in this study, including AISI316L austenitic stainless steel and aluminium alloy. The rutile-based coatings were fabricated by magnetron sputter deposition of a pure titanium coating first, and then thermal oxidation of the coated specimens to partially convert the titanium coating to rutile oxide and to promote interracial reactions which can significantly enhance the coating-substrate adhesion strength. The structures and properties of the coating-substrate systems were characterized by a variety of analytical and experimental techniques, including X-ray diffraction, glow discharge spectrometry, high resolution SEM, nanoindentation, microscratch, friction and wear testing, as well as electrochemical testing. The results show that the friction and wear properties, as well as the corrosion resistance of the metallic alloys can be significant enhanced by surface engineering with rutile-TiO2.

  1. Fabrication and Characterisation of Rutile-TiO2 Coatings on Metallic Alloy Substrates

    Institute of Scientific and Technical Information of China (English)

    Y. Sun; D. Siva Rama Krishna

    2004-01-01

    In the present work, attempts have been made to extend the use of the tribological and chemical properties of rutile-TiO2 to metallic alloy systems, by forming a rutile coating on the metallic substrates. Two metallic alloys were selected in this study, including AISI316L austenitic stainless steel and aluminium alloy. The rutile-based coatings were fabricated by magnetron sputter deposition of a pure titanium coating first, and then thermal oxidation of the coated specimens to partially convert the titanium coating to rutile oxide and to promote interfacial reactions which can significantly enhance the coating-substrate adhesion strength. The structures and properties of the coating-substrate systems were characterized by a variety of analytical and experimental techniques, including X-ray diffraction, glow discharge spectrometry, high resolution SEM, nanoindentation, microscratch, friction and wear testing, as well as electrochemical testing. The results show that the friction and wear properties, as well as the corrosion resistance of the metallic alloys can be significant enhanced by surface engineering with rutile-TiO2.

  2. Flexible metal–insulator–metal capacitors on polyethylene terephthalate plastic substrates

    International Nuclear Information System (INIS)

    Realization of flexible electronic devices on polyethylene terephthalate flexible plastic substrates is reported. Metal–insulator–metal capacitors have been fabricated using radio frequency sputtered deposited thin films of Nb2O5 on the flexible substrate. Good electrical characteristics have been obtained in terms of quadratic voltage coefficient of capacitance, high capacitance density (∼ 11 fF µm−2), high dielectric constant (∼37) and low dissipation factor (<0.1). Besides, in repetitive bending test, the devices show excellent electrical stability and high mechanical flexibility due to the high ductility of niobium and low-temperature processing used in this study. (paper)

  3. Layered transition metal dichalcogenides: promising near-lattice-matched substrates for GaN growth

    OpenAIRE

    Gupta, Priti; A. A. Rahman; Subramanian, Shruti; Gupta, Shalini; Thamizhavel, Arumugam; Orlova, Tatyana; Rouvimov, Sergei; Vishwanath, Suresh; Protasenko, Vladimir; Laskar, Masihhur R.; Xing, Huili Grace; Jena, Debdeep; Bhattacharya, Arnab

    2015-01-01

    Most III-nitride semiconductors are grown on non-lattice-matched substrates like sapphire or silicon due to the extreme difficulty of obtaining a native GaN substrate. We show that several layered transition-metal dichalcogenides are closely lattice matched to GaN and report the growth of GaN on a range of such layered materials. We report detailed studies of the growth of GaN on mechanically-exfoliated flakes WS$_2$ and MoS$_2$ by metalorganic vapour phase epitaxy. Structural and optical cha...

  4. Kelvin probe force microscopy of C60 on metal substrates: towards molecular resolution

    International Nuclear Information System (INIS)

    Surface workfunction changes upon C60 adsorption onto different metal single crystals are investigated by Kelvin probe force microscopy (KPFM). Literature values for similar metal/organic systems, showing a broad variation for both the measured metal workfunction and workfunction change, are compared to the acquired KPFM values. Good agreement is found between nanoscopic KPFM results and macroscopic photoelectron spectroscopy or Kelvin probe literature data. The model of a linear dependence between the metal substrate workfunction and the C60-induced workfunction change is confirmed. Former numerical simulations predicted a lateral quantitative KPFM resolution in the range of 10 nm, in this work results are published that show the achievement of this resolution with Cr coated, sharp tips. Furthermore, numerical simulations are presented that show the possibility of molecular contrast for KPFM

  5. Streamlining CdSe/CdS PEC characteristics using Cd metal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Martirosyan, S. [Department of Chemical Technologies and Ecology, State Engineering University of Armenia, Teryan Str. 105, Yerevan (Armenia)

    2001-12-15

    Ti or Ni metals - used conventionally as substrates - were substituted with Cd metal to improve the output characteristics and the reproducibility of the CdSe/CdS PEC (photoelectrochemical converter - photoelectrochemical solar cell). This approach proved valid and the following mean results were obtained: light to electric energy efficiency - Ca. 4.5% filling factor - approx. 0.37, open-circuit voltage - around 500mV and short-circuited current density - about 35mA/cm{sup 2} at light illumination intensity of 70mW/cm{sup 2}.

  6. Transfer-Free Electrical Insulation of Epitaxial Graphene from its Metal Substrate

    DEFF Research Database (Denmark)

    Lizzit, Silvano; Larciprete, Rosanna; Lacovig, Paolo;

    2012-01-01

    High-quality, large-area epitaxial graphene can be grown on metal surfaces, but its transport properties cannot be exploited because the electrical conduction is dominated by the substrate. Here we insulate epitaxial graphene on Ru(0001) by a stepwise intercalation of silicon and oxygen, and the...... eventual formation of a SiO2 layer between the graphene and the metal. We follow the reaction steps by X-ray photoemission spectroscopy and demonstrate the electrical insulation using a nanoscale multipoint probe technique....

  7. Long-range surface plasmons in dielectric-metal-dielectric structure with highly anisotropic substrates

    Science.gov (United States)

    Nagaraj; Krokhin, A. A.

    2010-02-01

    We present a theoretical study of long-range surface plasmons propagating in a thin metallic film clad between two identical uniaxial anisotropic dielectric crystals. We show that the proper orientation of the optical axis of the crystal with respect to the metal surface enhances the propagation length of surface plasmons. Since the proper orientation depends on surface plasmon frequency, we give the results for the propagation length in a wide range of frequencies, including the telecommunication region. To increase the role of anisotropy, we consider artificial substrates from photonic crystals, which possess an order of magnitude stronger anisotropy than the natural optical crystals. We propose Kronig-Penney model for plasmonic crystal where the substrate is a periodic sequence of dielectric delta peaks. In this model the dispersion relation for surface plasmon has a band structure where the band width tends to zero when the frequency approaches the resonant frequency.

  8. Small divergence substrate emitting quantum cascade laser by subwavelength metallic grating.

    Science.gov (United States)

    Yao, Dan-Yang; Zhang, Jin-Chuan; Liu, Ying-Hui; Zhuo, Ning; Jia, Zhi-Wei; Liu, Feng-Qi; Wang, Zhan-Guo

    2015-05-01

    Metallic periodic structure in subwavelength scale offers an exciting way to couple light into surface plasmons (SPs), thus manipulating the properties of near-field optics. We show that subwavelength metallic grating (SMG) defined on the substrate side of substrate emitting quantum cascade lasers enables far-field improvement in mid-infrared spectrum. The SMG is designed to tailor the interaction of SPs with single mode transverse magnetic light. The experiment results are in good agreement with the simulated model. A far-field full width at half maximum (FWHM) divergence angle of 3.9 ° in the direction perpendicular to the laser waveguide layers is obtained, improved by a factor of 8.5 compared with traditional surface emitting device. PMID:25969241

  9. Cube-textured metal substrates for reel-to-reel processing of coated conductors

    DEFF Research Database (Denmark)

    Wulff, Anders Christian

    This thesis presents the results of a study aimed at investigating important fabrication aspects of reel-to-reel processing of metal substrates for coated conductors and identifying a new substrate candidate material with improved magnetic properties. The eect of mechanical polishing on surface...... roughness and texture in Ni-5at.%W tapes in the cold-rolled condition was studied as a function of polishing grade. The surface roughness of the tape in the polished and annealed condition, and after subsequent coating with a Gd2Zr2O7 buer layer was investigated taking grain boundaries into account. It was...... observed that the initial mean surface roughness decreased after annealing except after very ne polishing. Additionally, the roughness of the buer layers were found to increase slightly for the ne polished substrates. Grain boundary grooving was observed to impose a lower limit for the mean surface...

  10. Chemical Stripping of ceramic films of titanium aluminum nitride from hard metal substrates

    OpenAIRE

    U. Bardi; D. Bonacchi; Rizzi, G.; Scrivani, A.

    2003-01-01

    We report here the result of a study of different chemical stripping methodologies for ceramic coatings deposited by PVD on hard metal substrates. We show that an approach based on the study of the system by surface science techniques leads to the possibility of developing effective stripping methods as well as guidelines for improving the process. We will report about two methods tested for the stripping of layers of titanium aluminum nitride (TINALOX) deposited by Physical Vapor De...

  11. Flexible Metal Oxide/Graphene Oxide Hybrid Neuromorphic Transistors on Flexible Conducting Graphene Substrates.

    Science.gov (United States)

    Wan, Chang Jin; Liu, Yang Hui; Feng, Ping; Wang, Wei; Zhu, Li Qiang; Liu, Zhao Ping; Shi, Yi; Wan, Qing

    2016-07-01

    Flexible metal oxide/graphene oxide hybrid multi-gate neuromorphic transistors are fabricated on flexible conducting graphene substrates. Dendritic integrations in both spatial and temporal modes are emulated, and spatiotemporal correlated logics are obtained. A proof-of-principle visual system model for emulating Lobula Giant Motion Detector neuron is also investigated. The results are of great significance for flexible sensors and neuromorphic cognitive systems. PMID:27159546

  12. Surface-Enhanced Raman Scattering Study on Graphene-Coated Metallic Nanostructure Substrates

    OpenAIRE

    Hao, Qingzhen; Wang, Bei; Bossard, Jeremy A.; Kiraly, Brian; Zeng, Yong; Chiang, I-Kao; Jensen, Lasse; Werner, Douglas H.; Huang, Tony Jun

    2012-01-01

    Graphene, which has a linear electronic band structure, is widely considered as a semimetal. In the present study, we combine graphene with conventional metallic surface-enhanced Raman scattering (SERS) substrates to achieve higher sensitivity of SERS detection. We synthesize high-quality, single-layer graphene sheets by chemical vapor deposition (CVD) and transfer them from copper foils to gold nanostructures, i.e., nanoparticle or nanohole arrays. SERS measurements are carried out on methyl...

  13. Development of 1 m HTS conductor using YBCO on textured metal substrate

    International Nuclear Information System (INIS)

    We fabricated 1 m high temperature superconducting conductor (HTS conductor) using YBa2Cu3O7-x coated conductors (YBCO tapes) on textured metal substrates, which are expected to be lower in cost than YBCO tapes using ion-beam assisted deposition. Those substrate and intermediate layers were manufactured by Furukawa Electric, and YBCO and a protective layer were applied to the intermediate layer by Chubu Electric Power. Before fabricating the conductor, a 0.1 mm thick copper tape was soldered to the YBCO tape, and 10 mm wide YBCO tape was divided into three strips by a YAG laser. To have sufficient current capacity for 1 kA, a two-layer conductor was fabricated, and its critical current (Ic) was 1976 A, but the magnetic properties of the textured metal substrates affected the increase in AC loss. In a low current region, the AC loss in this conductor was much higher than the Norris strip model, but approached the Norris strip model in the high current region because the magnetization was almost saturated. Low AC loss of 0.144 W/m at 1 kArms was achieved even though the conductor had a small outer diameter of 20 mm and was composed of YBCO tapes with magnetic substrates.

  14. Development of 1 m HTS conductor using YBCO on textured metal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, M., E-mail: m-yagi@ch.furukawa.co.j [Furukawa Electric Co., Ltd, 6, Yawata-Kaigandori, Ichihara, Chiba 290-8555 (Japan); Sakamoto, H. [Furukawa Electric Co., Ltd, 500, Kiyotaki-machi, Nikko, Tochigi 321-1493 (Japan); Mukoyama, S. [Furukawa Electric Co., Ltd, 6, Yawata-Kaigandori, Ichihara, Chiba 290-8555 (Japan); Yamamoto, K. [Furukawa Electric Co., Ltd, 500, Kiyotaki-machi, Nikko, Tochigi 321-1493 (Japan); Amemiya, N. [Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510 (Japan); Nagaya, S.; Kashima, N. [Chubu Electric Power Co., Inc., 20-1, Kitasekiyama, Ohdaka-cho, Midori-ku, Nagoya 459-8522 (Japan); Shiohara, Y. [Superconductivity Research Laboratory, 1-10-13, Shinonome, Koto-ku, Tokyo 135-0062 (Japan)

    2009-10-15

    We fabricated 1 m high temperature superconducting conductor (HTS conductor) using YBa{sub 2}Cu{sub 3}O{sub 7-x} coated conductors (YBCO tapes) on textured metal substrates, which are expected to be lower in cost than YBCO tapes using ion-beam assisted deposition. Those substrate and intermediate layers were manufactured by Furukawa Electric, and YBCO and a protective layer were applied to the intermediate layer by Chubu Electric Power. Before fabricating the conductor, a 0.1 mm thick copper tape was soldered to the YBCO tape, and 10 mm wide YBCO tape was divided into three strips by a YAG laser. To have sufficient current capacity for 1 kA, a two-layer conductor was fabricated, and its critical current (I{sub c}) was 1976 A, but the magnetic properties of the textured metal substrates affected the increase in AC loss. In a low current region, the AC loss in this conductor was much higher than the Norris strip model, but approached the Norris strip model in the high current region because the magnetization was almost saturated. Low AC loss of 0.144 W/m at 1 kA{sub rms} was achieved even though the conductor had a small outer diameter of 20 mm and was composed of YBCO tapes with magnetic substrates.

  15. Effect of hydroxyapatite thickness on metal ion release from Ti6Al4V substrates.

    Science.gov (United States)

    Sousa, S R; Barbosa, M A

    1996-02-01

    The electrochemical dissolution behaviour of Ti6Al4V alloy coated with hydroxyapatite (HA) by plasma spraying was studied in Hank's balanced salt solution (HBSS) and compared with that of polished and grit-blasted passivated surfaces. Two different nominal thicknesses of HA (50 and 200 micro m) were used. Taking a polished passivated surface as reference, grit blasting of the substrate increased the electrical charge used in the oxidation of Ti6Al4V alloy at constant potential, as a result of increased surface area. However, only HA coatings with a thickness of 200 micro m were capable of reducing the charge to values lower than those measured for polished surfaces. Electrochemical impedance spectroscopy has also shown that only 200 micro m thick coatings are effective in reducing the oxidation rate of the substrate. Furthermore, in potentiostatic experiments the 50 micro m thick coating detached from the substrate, which did not occur with the 200 micro m thick coating. However, after 6 months immersion in HBSS, detachment occurred in some regions of both coatings. No titanium, aluminium or vanadium were detected in solution by electrothermal atomic absorption spectroscopy. These data indicate that HA is an effective barrier to metal ion release, even for the thinner coatings, due to formation of metal phosphates or to incorporation of metal ions in the HA structure. PMID:8938233

  16. Recent Developments of Flexible CdTe Solar Cells on Metallic Substrates: Issues and Prospects

    Directory of Open Access Journals (Sweden)

    M. M. Aliyu

    2012-01-01

    Full Text Available This study investigates the key issues in the fabrication of CdTe solar cells on metallic substrates, their trends, and characteristics as well as effects on solar cell performance. Previous research works are reviewed while the successes, potentials, and problems of such technology are highlighted. Flexible solar cells offer several advantages in terms of production, cost, and application over glass-based types. Of all the metals studied as substrates for CdTe solar cells, molybdenum appears the most favorable candidate, while close spaced sublimation (CSS, electrodeposition (ED, magnetic sputtering (MS, and high vacuum thermal evaporation (HVE have been found to be most common deposition technologies used for CdTe on metal foils. The advantages of these techniques include large grain size (CSS, ease of constituent control (ED, high material incorporation (MS, and low temperature process (MS, HVE, ED. These invert-structured thin film CdTe solar cells, like their superstrate counterparts, suffer from problems of poor ohmic contact at the back electrode. Thus similar strategies are applied to minimize this problem. Despite the challenges faced by flexible structures, efficiencies of up to 13.8% and 7.8% have been achieved in superstrate and substrate cell, respectively. Based on these analyses, new strategies have been proposed for obtaining cheaper, more efficient, and viable flexible CdTe solar cells of the future.

  17. Growth and spectroscopic characterization of monolayer and few-layer hexagonal boron nitride on metal substrates

    Science.gov (United States)

    Feigelson, Boris N.; Bermudez, Victor M.; Hite, Jennifer K.; Robinson, Zachary R.; Wheeler, Virginia D.; Sridhara, Karthik; Hernández, Sandra C.

    2015-02-01

    Atomically thin two dimensional hexagonal boron nitride (2D h-BN) is one of the key materials in the development of new van der Waals heterostructures due to its outstanding properties including an atomically smooth surface, high thermal conductivity, high mechanical strength, chemical inertness and high electrical resistance. The development of 2D h-BN growth is still in the early stages and largely depends on rapid and accurate characterization of the grown monolayer or few layers h-BN films. This paper demonstrates a new approach to characterizing monolayer h-BN films directly on metal substrates by grazing-incidence infrared reflection absorption spectroscopy (IRRAS). Using h-BN films grown by atmospheric-pressure chemical vapor deposition on Cu and Ni substrates, two new sub-bands are found for the A2u out-of-plane stretching mode. It is shown, using both experimental and computational methods, that the lower-energy sub-band is related to 2D h-BN coupled with substrate, while the higher energy sub-band is related to decoupled (or free-standing) 2D h-BN. It is further shown that this newly-observed fine structure in the A2u mode can be used to assess, quickly and easily, the homogeneity of the h-BN-metal interface and the effects of metal surface contamination on adhesion of the layer.

  18. Metal particle compaction during drop-substrate impact for inkjet printing and drop-casting processes

    Science.gov (United States)

    Clancy, I.; Amarandei, G.; Nash, C.; Glowacki, B. A.

    2016-02-01

    Direct coating methods using metal particles from aqueous solutions or solvent-based inks become central in the roll-to-roll fabrication processes as these methods can lead to continuous or pre-defined conductive layers on a large variety of substrates. For good electrical conductivity, the metal particles have to be brought into contact, and traditionally, additional sintering treatments are required. Such treatments can degrade the sensitive substrates as paper or polymer films. In this study, the possibility of obtaining conductive layers at room temperature is investigated for direct coating methods with an emphasis on drop-casting and inkjet printing. Thus, it is shown that electrical conductive layers can be achieved if the metal particles can compact during the drop-substrate impact interaction. It is theoretically shown that the compaction process is directly related to the particle and ink drop size, the initial fractional particle loading of the ink, solvent viscosity, and drop velocity. The theoretical predictions on compaction are experimentally validated, and the particle compaction's influence on changes in the electrical conductivity of the resulting layers is demonstrated.

  19. Organic substrates as electron donors in permeable reactive barriers for removal of heavy metals from acid mine drainage.

    Science.gov (United States)

    Kijjanapanich, P; Pakdeerattanamint, K; Lens, P N L; Annachhatre, A P

    2012-12-01

    This research was conducted to select suitable natural organic substrates as potential carbon sources for use as electron donors for biological sulphate reduction in a permeable reactive barrier (PRB). A number of organic substrates were assessed through batch and continuous column experiments under anaerobic conditions with acid mine drainage (AMD) obtained from an abandoned lignite coal mine. To keep the heavy metal concentration at a constant level, the AMD was supplemented with heavy metals whenever necessary. Under anaerobic conditions, sulphate-reducing bacteria (SRB) converted sulphate into sulphide using the organic substrates as electron donors. The sulphide that was generated precipitated heavy metals as metal sulphides. Organic substrates, which yielded the highest sulphate reduction in batch tests, were selected for continuous column experiments which lasted over 200 days. A mixture of pig-farm wastewater treatment sludge, rice husk and coconut husk chips yielded the best heavy metal (Fe, Cu, Zn and Mn) removal efficiencies of over 90%. PMID:23437664

  20. Substrate temperature control for the formation of metal nanohelices by glancing angle deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sumigawa, Takashi, E-mail: sumigawa@cyber.kues.kyoto-u.ac.jp; Sakurai, Atsushi; Iwata, Kazuya; Chen, Shaoguang; Kitamura, Takayuki [Department of Mechanical Engineering and Science, Kyoto University, Kyoto-daigaku-Katsura, Nishikyo-ku, Kyoto 615-8540 (Japan); Tanie, Hisashi [Research and Development Group, Hitachi, Ltd., 832-2, Horiguchi, Hitachinaka, Ibaraki 312-0034 (Japan)

    2015-11-15

    The targets of this study are to develop a device to precisely control the temperature during glancing angle deposition, to make films consisting of low melting temperature metal nanoelements with a controlled shape (helix), and to explore the substrate temperature for controlling the nanoshapes. A vacuum evaporation system capable of both cooling a substrate and measurement of its temperature was used to form thin films consisting of arrays of Cu and Al nanohelices on silicon substrates by maintaining the substrate temperature at T{sub s}/T{sub m} < 0.22 (T{sub s} is the substrate temperature and T{sub m} is the melting temperature of target material). The critical T{sub s}/T{sub m} to produce Cu and Al nanohelices corresponds to the transitional homologous temperature between zones I and II in the structure zone model for the solid film, where surface diffusion becomes dominant. X-ray diffraction analysis indicated that the Cu and Al nanohelix thin films were composed of coarse oriented grains with diameters of several tens of nanometers.

  1. Metal-doped ZnS(O) thin films on glass substrates using chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Inamdar, Akbar I.; Lee, Seulgi; Kim, Duhwan [Department of Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Gurav, K.V.; Kim, J.H. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Im, Hyunsik, E-mail: hyunsik7@dongguk.edu [Department of Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Jung, Woong [Department of Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Kim, Hyungsang [Department of Physics, Dongguk University, Seoul 100-715 (Korea, Republic of)

    2013-06-30

    Zinc sulfide (ZnS(O)) thin films doped with Mn, Ni, and Co ions are synthesized by chemical bath deposition technique onto glass substrates. X-ray diffraction study reveals that the undoped and metal-doped ZnS(O) films possess a hexagonal wurtzite crystal structure. The morphological change, upon metal-ions doping, from nanorod structures to cluster (Mn doping), compact (Ni doping), and granular shapes (Co doping) is observed. X-ray photoelectron spectroscopy reveals the presence and incorporation of metal ions into ZnS(O) lattice sites and the formation of a metal–ZnS combined structure. The band gap energy of the undoped ZnS(O) film is found to be larger than 4.0 eV, while it is 3.8, 3.7, and 3.6 eV for the Mn–ZnS(O), Ni–ZnS(O), and Co–ZnS(O) films, respectively. All the undoped and metal-doped ZnS(O) samples exhibit blue luminescence, which originates from the surface defects and trap centers. Thus, the photoluminescence (PL) (blue light emission) is due to the radiative recombination from various trap levels (shallow donor levels) to the valence band. The decrease in the PL peak intensity for the doped samples indicates the reduction of surface defects suggesting the incorporation of metal ions into the host lattice of ZnS(O). Based on the PL results, the PL energy-level diagram for the undoped and metal-doped ZnS(O) samples is proposed. - Highlights: • We report on synthesis of metal-doped ZnS (O) using a chemical bath deposition. • Structural properties of metal-doped ZnS films are investigated. • Optical properties of metal-doped ZnS (O) films are studied. • Optical band-gap energies are extracted. • Photoluminescence model for different metal–dopants is presented.

  2. Characterization of the porous anodic alumina nanostructures with a metal interlayer on Si substrates

    International Nuclear Information System (INIS)

    Porous anodic alumina (PAA) films produced by the anodization technique have made possible the mass production of porous nano-scale structures where the pore height and diameter are controllable. A metal interlayer is observed to have a significant influence on the characteristics of these PAA nanostructures. In this study, we investigate in-depth the effect of the current density on the properties of porous anodic alumina nanostructures with a metal interlayer. A thin film layer of tungsten (W) and titanium (Ti) was sandwiched between a porous anodic alumina film and a silicon (Si) substrate to form PAA/W/Si and PAA/Ti/Si structures. The material and optical characteristics of the porous anodic alumina nanostructures, with and without a metal interlayer, on silicon substrates were studied using the scanning electron microscopy, X-ray diffraction (XRD), and temperature-dependent photoluminescence (PL) measurements. The current densities of the porous anodic alumina nanostructures with the metal interlayer are higher than for the PAA/Si, resulting in an increase of the growth rate of the oxide layer. It can be observed from the X-ray diffraction curves that there is more aluminum oxide inside the structure with the metal interlayer. Furthermore, it has been found that there is a reduction in the photoluminescence intensity of the oxygen vacancy with only one electron due to the formation of oxygen vacancies inside the aluminum oxide during the re-crystallization process. This leads to competition between the two kinds of different oxygen-deficient defect centers (F+ and F centers) in the carrier recombination mechanism from the PL spectra of the porous anodic alumina nanostructures, with and without a metal interlayer, on silicon substrates. -- Highlights: • Study of porous anodic alumina (PAA) films with metal interlayers on silicon. • The highly ordered PAA film with a fairly regular nano-porous structure. • The luminescence properties of PAA films were

  3. Ab initio investigations of magnetic properties of ultrathin transition-metal films on 4d substrates

    International Nuclear Information System (INIS)

    In this thesis, we investigate the magnetic properties of 3d transition-metal monolayers on 4d transition-metal substrates by means of state of the art first-principles quantum theory. In order to reveal the underlying physics of these systems we study trends by performing systematic investigations across the transition-metal series. Case studies are presented for which Rh has been chosen as exemplary 4d substrate. We consider two substrate orientations, a square lattice provided by Rh(001) and a hexagonal lattice provided by Rh(111). We find, all 3d transition-metal (V, Cr, Mn, Fe, Co and Ni) monolayers deposited on the Rh substrate are magnetic and exhibit large local moments which follow Hund's rule with a maximum magnetic moment for Mn of about 3.7 μB depending on the substrate orientation. The largest induced magnetic moment of about 0.46 μB is found for Rh atoms adjacent to the Co(001)-film. On Rh(001) we predict a ferromagnetic (FM) ground state for V, Co and Ni, while Cr, Mn and Fe monolayers favor a c(2 x 2) antiferromagnetic (AFM) state, a checkerboard arrangement of up and down magnetic moments. The magnetic anisotropy energies of these ultrathin magnetic films are calculated for the FM and the AFM states. With the exception of V and Cr, the easy axis of the magnetization is predicted to be in the film plane. With the exception of Fe, analogous results are obtained for the 3d-metal monolayers on Rh(111). For Fe on Rh(111) a novel magnetic ground state is predicted, a double-row-wise antiferromagnetic state along the [11 anti 2] direction, a sequence of ferromagnetic double-rows of atoms, whose magnetic moments couple antiferromagnetically from double row to double row. The magnetic structure can be understood as superposition of a left- and right-rotating flat spin spiral. In a second set of case studies the properties of an Fe monolayer deposited on varies hexagonally terminated hcp (0001) and fcc (111) surfaces of 4d-transition metals (Tc, Ru, Rh, to

  4. Ab initio investigations of magnetic properties of ultrathin transition-metal films on 4d substrates

    Energy Technology Data Exchange (ETDEWEB)

    Al-Zubi, Ali

    2010-12-22

    In this thesis, we investigate the magnetic properties of 3d transition-metal monolayers on 4d transition-metal substrates by means of state of the art first-principles quantum theory. In order to reveal the underlying physics of these systems we study trends by performing systematic investigations across the transition-metal series. Case studies are presented for which Rh has been chosen as exemplary 4d substrate. We consider two substrate orientations, a square lattice provided by Rh(001) and a hexagonal lattice provided by Rh(111). We find, all 3d transition-metal (V, Cr, Mn, Fe, Co and Ni) monolayers deposited on the Rh substrate are magnetic and exhibit large local moments which follow Hund's rule with a maximum magnetic moment for Mn of about 3.7 {mu}{sub B} depending on the substrate orientation. The largest induced magnetic moment of about 0.46 {mu}{sub B} is found for Rh atoms adjacent to the Co(001)-film. On Rh(001) we predict a ferromagnetic (FM) ground state for V, Co and Ni, while Cr, Mn and Fe monolayers favor a c(2 x 2) antiferromagnetic (AFM) state, a checkerboard arrangement of up and down magnetic moments. The magnetic anisotropy energies of these ultrathin magnetic films are calculated for the FM and the AFM states. With the exception of V and Cr, the easy axis of the magnetization is predicted to be in the film plane. With the exception of Fe, analogous results are obtained for the 3d-metal monolayers on Rh(111). For Fe on Rh(111) a novel magnetic ground state is predicted, a double-row-wise antiferromagnetic state along the [11 anti 2] direction, a sequence of ferromagnetic double-rows of atoms, whose magnetic moments couple antiferromagnetically from double row to double row. The magnetic structure can be understood as superposition of a left- and right-rotating flat spin spiral. In a second set of case studies the properties of an Fe monolayer deposited on varies hexagonally terminated hcp (0001) and fcc (111) surfaces of 4d

  5. Selective synthesis of double helices of carbon nanotube bundles grown on treated metallic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes-Sodi, Felipe; Iniguez-Rabago, Agustin; Rosas-Melendez, Samuel; Ballesteros-Villarreal, Monica [Departamento de Fisica y Matematicas, Universidad Iberoamericana, Prolongacion Paseo de la Reforma 880, Lomas de Santa Fe (Mexico); Vilatela, Juan J. [IMDEA Materials Institute, E.T.S. de Ingenieros de Caminos, Madrid (Spain); Reyes-Gutierrez, Lucio G.; Jimenez-Rodriguez, Jose A. [Ingenieria Industrial, Grupo JUMEX, Ecatepec de Morelos, Estado de Mexico (Mexico); Palacios, Eduardo [Lab. de Microscopia Electronica de Ultra Alta Resolucion, Instituto Mexicano del Petroleo, San Bartolo Atepehuacan (Mexico); Terrones, Mauricio [Department of Physics, Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, University Park, PA (United States); Research Center for Exotic Nanocarbons (JST), Shinshu University, Nagano (Japan)

    2012-12-15

    Double-helix microstructures consisting of two parallel strands of hundreds of multi-walled carbon nanotubes (MWCNTs) have been synthesized by chemical vapour deposition of ferrocene/toluene vapours on metal substrates. Growth of coiled carbon nanostructures with site selectivity is achieved by varying the duration of thermochemical pretreatment to deposit a layer of SiO{sub x} on the metallic substrate. Production of multibranched structures of MWCNTs converging in SiO{sub x} microstructure is also reported. In the abstract figure, panel (a) shows a coloured micrograph of a typical double-helix coiled microstructure of MWCNTs grown on SiO{sub x} covered steel substrate. Green and blue show each of the two individual strands of MWCNTs. Panel (b) is an amplification of a SiO{sub x} microparticle (white) on the tip of the double-stranded coil (green and blue). The microparticle guides the collective growth of hundreds of MWCNTs to form the coiled structure. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Protein-associated water and secondary structure effect removal of blood proteins from metallic substrates.

    Science.gov (United States)

    Anand, Gaurav; Zhang, Fuming; Linhardt, Robert J; Belfort, Georges

    2011-03-01

    Removing adsorbed protein from metals has significant health and industrial consequences. There are numerous protein-adsorption studies using model self-assembled monolayers or polymeric substrates but hardly any high-resolution measurements of adsorption and removal of proteins on industrially relevant transition metals. Surgeons and ship owners desire clean metal surfaces to reduce transmission of disease via surgical instruments and minimize surface fouling (to reduce friction and corrosion), respectively. A major finding of this work is that, besides hydrophobic interaction adhesion energy, water content in an adsorbed protein layer and secondary structure of proteins determined the access and hence ability to remove adsorbed proteins from metal surfaces with a strong alkaline-surfactant solution (NaOH and 5 mg/mL SDS in PBS at pH 11). This is demonstrated with three blood proteins (bovine serum albumin, immunoglobulin, and fibrinogen) and four transition metal substrates and stainless steel (platinum (Pt), gold (Au), tungsten (W), titanium (Ti), and 316 grade stainless steel (SS)). All the metallic substrates were checked for chemical contaminations like carbon and sulfur and were characterized using X-ray photoelectron spectroscopy (XPS). While Pt and Au surfaces were oxide-free (fairly inert elements), W, Ti, and SS substrates were associated with native oxide. Difference measurements between a quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance spectroscopy (SPR) provided a measure of the water content in the protein-adsorbed layers. Hydrophobic adhesion forces, obtained with atomic force microscopy, between the proteins and the metals correlated with the amount of the adsorbed protein-water complex. Thus, the amount of protein adsorbed decreased with Pt, Au, W, Ti and SS, in this order. Neither sessile contact angle nor surface roughness of the metal substrates was useful as predictors here. All three globular proteins

  7. Controlling Electronic and Geometrical Structure of Honeycomb-Lattice Materials Supported on Metal Substrates : Graphene and Hexagonal Boron Nitride

    OpenAIRE

    Vinogradov, Nikolay

    2013-01-01

    The present thesis is focused on various methods of controlling electronic and geometrical structure of two-dimensional overlayers adsorbed on metal surfaces exemplified by graphene and hexagonal boron nitride (h-BN) grown on transition metal (TM) substrates. Combining synchrotron-radiation-based spectroscopic and various microscopic techniques with in situ sample preparation, we are able to trace the evolution of overlayer electronic and geometrical properties in overlayer/substrate systems,...

  8. Atomistic view in the initial stages of growth of epitaxial graphene on metal substrates

    Science.gov (United States)

    Zhang, Zhenyu

    2011-03-01

    For both fundamental studies and potential development of graphene electronics, it is pressing to search for reliable methods for mass production of quality graphene. Epitaxial growth of graphene on catalytic metal substrates combined with post-growth transfer has become a promising route towards this goal [1,2]. However, to better control the quality and yield of graphene, a comprehensive understanding of the growth kinetics is essential. In particular, how the carbon atoms adsorbed on the metal surface (or dissolved into the metal) meet to nucleate into stable carbon islands will greatly influence both the growth rate and quality of larger carbon entities such as graphene sheets. In this talk, we first show that the delicate competition between carbon-carbon bonding and carbon-metal bonding dictates the initial nucleation sites of graphene on metal surfaces. These results are discussed in connection with the experimental findings that on Ir(111) and Ru(0001) substrates graphene nucleates from the step edges [4,5]. We also predict that on Cu(111) nucleation should take place everywhere on a terrace. Next we study larger carbon clusters on Cu(111) and explicitly compare the stability of linear and compact structures. We find that the linear carbon ``nanoarches'' are more stable than compact islands consisting of up to 13 carbon atoms, and these nanoarched structures may serve as the missing bridge between carbon dimers and larger graphene nanodomes. Based on these improved understanding of the atomistic rate processes involved, we propose a few kinetic pathways that may lead to better growth control of bilayer graphene and graphene nanoribbons as elemental building blocks for developing graphene electronics. Work done in collaboration with Hua Chen, Wenguang Zhu, Robert Van Wesep, Wei Chen, Ping Cui, and Haiping Lan, and supported by USDOE, USNSF, and NNSF of China.

  9. Growth of CsLiB6O10 thin films on Si substrate by pulsed laser deposition using SiO2 and CaF2 as buffer layers

    Science.gov (United States)

    Yeo, J. S.; Akella, A.; Huang, T. F.; Hesselink, L.

    1998-03-01

    CsLiB6O10 (CLBO) thin films are grown on Si (100) and (111) substrates using lower index SiO2 and CaF2 as buffer layers by pulsed KrF (248 nm) excimer laser ablation of stoichiometric CLBO targets over a temperature range of 425 to 725°C. A CaF2 buffer layer is grown on Si by laser ablation while SiO2 is prepared by standard thermal oxidation. From extended x-ray analysis, it is determined that CaF2 is growth with preferred orientation on Si (100) at temperatures lower than 525°C while on Si (111) substrate, CaF2 is grown epitaxially over the temperature range; this agrees well with observed reflection high energy electron diffraction patterns. X-ray 2θ-scans indicate that crystalline CLBO are grown on SiO2/Si and CaF2/Si (100). Analysis of reflectance spectra from CLBO/SiO2/Si yields the absorption edge at 182 nm. Surface roughness of the CaF2 and CLBO/CaF2/Si film are 19 and 15 nm, respectively. This relatively rough surface caused by the ablation of wide bandgap CaF2 and CLBO limits the application of CLBO for waveguiding measurement.

  10. Angular properties of pure and Ca-substituted YBa2Cu3O7-δ superconducting thin films grown on SrTiO3 and CeO2 buffered Al2O3 substrates

    International Nuclear Information System (INIS)

    In this work transport properties of superconducting 10 at.% Ca-substituted YBCO thin films grown on (1 0 0)-SrTiO3 single crystal substrate (STO) and superconducting pure and 10 at.% Ca-substituted YBCO thin films grown on CeO2 buffered Al2O3 substrates (CAO) have been analyzed as a function of the temperature, applied magnetic field and angle between magnetic field direction and the direction normal to the film surfaces. Particularly, the angular analysis provides an easy way to discriminate between isotropic point defects and correlated pinning sites. Despite the intragrain pinning mechanisms remained unaffected by Ca substitution, a detrimental effect on grain boundary properties clearly emerged for 10 at.% Ca concentration. This effect is enhanced in sample grown on CeO2 buffered sapphire where a more disturbed grain boundary is expected resulting in an enhancement of the correlated pinning, already observed in pure YBCO films grown on CAO, and in a reduction of the intrinsic pinning efficiency

  11. Floating substrate luminescence from silicon rich oxide metal-oxide-semiconductor devices

    International Nuclear Information System (INIS)

    The electro-optical properties of metal-oxide-semiconductor devices with embedded Si nanoparticles in silicon-rich (4 at.%) oxide films have been studied. Devices show intense visible continuous luminescence not only in the regular metal-oxide-semiconductor configuration, but when biased via surface electrodes (floating substrate) separated 10 μm. Electroluminescence manifests as extremely bright randomly scattered discrete spots on the gate area or the periphery of the devices depending on the bias direction. The mechanism responsible for the surface-electroluminescence has been related to the recombination of electron–hole pairs injected through enhanced current paths within the silicon-rich oxide film. - Highlights: ► Silicon rich oxide (SRO) based metal-oxide-semiconductor like luminescent devices. ► Electroluminescence (EL) in floating-substrate, horizontal electrodes configuration. ► EL is observed as multiple shining spots with surface electrodes. ► Preferential current paths established in the SRO between several electrodes

  12. Role of metallic substrate on the plasmon modes in double-layer graphene structures

    Science.gov (United States)

    Cruz, G. Gonzalez de la

    2015-07-01

    Novel heterostructures combining different layered materials offer new opportunities for applications and fundamental studies of collective excitations driven by interlayer Coulomb interactions. In this work, we have investigated the influence of the metallic-like substrate on the plasmon spectrum of a double layer graphene system and a structure consisting of conventional two-dimensional electron gas (2DEG) immersed in a semiconductor quantum well and a graphene sheet with an interlayer separation of d. Long-range Coulomb interactions between substrate and graphene layered systems lead a new set of spectrum plasmons. At long wavelengths (q→0) the acoustic modes (ω~q) depend, besides on the carrier density in each layer, on the distance between the first carrier layer and the substrate in both structures. Furthermore, in the relativistic/nonrelativistic layered structure an undamped acoustic mode emerges for a certain interlayer critical distance dc. On the other hand, the optical plasmon modes emerging from the coupling of the double-layer systems and the substrate, both start at finite frequency at q=0 in contrast to the collective excitation spectrum ω~q1/2 reported in the literature for double-layer graphene structures.

  13. Stretchable metal oxide thin film transistors on engineered substrate for electronic skin applications.

    Science.gov (United States)

    Romeo, Alessia; Lacour, Stphanie P

    2015-08-01

    Electronic skins aim at providing distributed sensing and computation in a large-area and elastic membrane. Control and addressing of high-density soft sensors will be achieved when thin film transistor matrices are also integrated in the soft carrier substrate. Here, we report on the design, manufacturing and characterization of metal oxide thin film transistors on these stretchable substrates. The TFTs are integrated onto an engineered silicone substrate with embedded strain relief to protect the devices from catastrophic cracking. The TFT stack is composed of an amorphous In-Ga-Zn-O active layer, a hybrid AlxOy/Parylene dielectric film, gold electrodes and interconnects. All layers are prepared and patterned with planar, low temperature and dry processing. We demonstrate the interconnected IGZO TFTs sustain applied tensile strain up to 20% without electrical degradation and mechanical fracture. Active devices are critical for distributed sensing. The compatibility of IGZO TFTs with soft and biocompatible substrates is an encouraging step towards wearable electronic skins. PMID:26738152

  14. High-density metallic nanogaps fabricated on solid substrates used for surface enhanced Raman scattering.

    Science.gov (United States)

    Lu, Gang; Li, Hai; Wu, Shixin; Chen, Peng; Zhang, Hua

    2012-02-01

    The Raman signal of adsorbed molecules can be significantly enhanced by utilizing metallic structures with high-density Raman hot spots used as surface enhanced Raman scattering (SERS) substrates. In this work, we develop a simple, convenient and tunable method to fabricate high-density Ag or Au nanogaps on Si wafers. These nanogaps can serve as Raman hot spots, leading to dramatic enhancement of the Raman signal. The high-density nanogaps can be formed by repeating the electroless deposition of Ag NPs (or Au NPs) and coating of p-aminothiophenol (PATP, a Raman probe) on the deposited Ag NPs (or Au NPs) through the self-assembly process. After removal of PATP by O(2) plasma, the as-fabricated SERS substrate can be reused for the detection of other molecules. PMID:22159183

  15. The effect of polyimide imidization conditions on adhesion strength of thin metal films on polyimide substrates

    CERN Document Server

    Yoo, S H

    1999-01-01

    The effects of Ar sup + RF plasma precleaning and polyimide curing conditions on the peel strength between Al thin films and polyimides have been studied. The BPDA-PDA polyimide precursor of PI-2611 (Du pont) was spin-coated and cured under various imidization conditions. The cured polyimide substrates were in-situ AR sup + RF plasma cleaned prior to metal deposition. Al-1 % Si-0.5 % Cu thin films were deposited onto the polyimide substrates by using DC magnetron sputtering. The peel strength was enhanced by Ar sup + RF plasma precleaning. The Al/modified PI specimen failed cohesively in the polyimide. The polyimide curing conditions strongly affect the peel strength in the Al/modified PI system.

  16. Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping

    Science.gov (United States)

    Glynn, Colm; Aureau, Damien; Collins, Gillian; O'Hanlon, Sally; Etcheberry, Arnaud; O'Dwyer, Colm

    2015-11-01

    Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species.Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings

  17. Facile graphene transfer directly to target substrates with a reusable metal catalyst

    Science.gov (United States)

    Mafra, D. L.; Ming, T.; Kong, J.

    2015-09-01

    High-throughput, roll-to-roll growth and transferring of high-quality, large-area chemical vapor deposited (CVD) graphene directly onto a target substrate with a reusable metal catalyst is an enabling technology for flexible optoelectronics. We explore the direct transfer via hot lamination of CVD graphene onto a flexible substrate, followed by electrochemical delamination (bubble transfer) of the graphene. The transfer method investigated here does not require any intermediate transfer layer and allows the copper to be reused, which will reduce the production cost and avoid the generation of chemical waste. Such integration is one necessary step forward toward the economical and industrial scale production of graphene. Our method bares promise in various applications. As an example, we fabricated flexible solution-gated graphene field-effect-transistors, which exhibited transconductance as high as 200 μS.High-throughput, roll-to-roll growth and transferring of high-quality, large-area chemical vapor deposited (CVD) graphene directly onto a target substrate with a reusable metal catalyst is an enabling technology for flexible optoelectronics. We explore the direct transfer via hot lamination of CVD graphene onto a flexible substrate, followed by electrochemical delamination (bubble transfer) of the graphene. The transfer method investigated here does not require any intermediate transfer layer and allows the copper to be reused, which will reduce the production cost and avoid the generation of chemical waste. Such integration is one necessary step forward toward the economical and industrial scale production of graphene. Our method bares promise in various applications. As an example, we fabricated flexible solution-gated graphene field-effect-transistors, which exhibited transconductance as high as 200 μS. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03892h

  18. Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping.

    Science.gov (United States)

    Glynn, Colm; Aureau, Damien; Collins, Gillian; O'Hanlon, Sally; Etcheberry, Arnaud; O'Dwyer, Colm

    2015-12-21

    Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species. PMID:26575987

  19. Deposition of perpendicular c-axis oriented BaM thin films on (001) Al{sub 2}O{sub 3} substrates by introducing an interfacial BaM buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhiyong, E-mail: xzy831230@yahoo.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhaoqing Science and Technology Center, Zhaoqing 526020 (China); Lan, Zhongwen; Sun, Ke; Yu, Zhong; Guo, Rongdi; Zhu, Guangwei; Huang, Xiaodong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2013-11-15

    M-type barium ferrite (BaM) thin films with two different structures (single layered and double layered) were deposited on (001) Al{sub 2}O{sub 3} single crystal substrates using an RF magnetron sputtering system. The changes in the surface morphologies, crystallographic and magnetic properties of BaM thin films corresponding to the different structures and substrate temperatures (T{sub s}) were investigated in detail. The results indicated that the interfacial BaM buffer layer plays an important role in improving the crystallographic and magnetic properties of BaM thin films. The single layered BaM thin films deposited at T{sub s}=300 °C and T{sub s}=500 °C are both randomly c-axis oriented. Whereas, by introducing a thin BaM layer which acts as an interfacial buffer layer, an excellent perpendicular c-axis orientation with an epitaxial structure for the double layered BaM thin film was obtained. The c-axis dispersion angle (Δθ{sub c}) decreased to 0.49°, and the perpendicular squareness ratio increased to 0.85 for the double layered film. The mechanism for improving the perpendicular c-axis orientation with an interfacial BaM buffer layer was attributed to two reasons. One is a relative increase in the nucleation sites for perpendicularly oriented grains over the nucleation sites for in-plane and/or randomly oriented grains, and the other is the release of the stress that comes from the interface between BaM thin film and Al{sub 2}O{sub 3} substrate. - Highlights: • BaM thin films were deposited on (001) Al{sub 2}O{sub 3} substrates by RF magnetron sputtering. • Single layered and double layered BaM films deposited at different T{sub s} were studied. • The single layered films are both randomly c-axis oriented. • The double layered film is perpendicularly c-axis oriented with an epitaxial texture. • The mechanism is attributed to the change of nucleation sites and release of stress.

  20. Picosecond Laser Machining of Metallic and Polymer Substrates for Fluidic Driven Self-Alignment

    Science.gov (United States)

    Römer, G. R. B. E.; Cerro, D. Arnaldo Del; Pohl, R.; Chang, B.; Liimatainen, V.; Zhou, Q.; Veld, A. J. Huis In `t.

    Fluidic self-alignment of micro-components relies on creating a receptor site that is able to confine a liquid droplet. When a micro-component is brought in contact with the droplet, capillary forces move the component to its final position. A method to stop the advancing of a liquid from a receptor site, consists of creating geometrical features, such as edges around the site. A picosecond pulsed laser source was used to create suitable edges in a metallic and a polyimide substrate. Subsequently, the self-alignment capabilities of these sites were tested. The receptor sites in polyimide showed the highest success rate.

  1. Picosecond Laser Machining of Metallic and Polymer Substrates for Fluidic Driven Self-Alignment

    OpenAIRE

    Römer, G.R.B.E.; Cerro, D. Arnaldo Del; Pohl, R.; Chang, B.; Liimatainen, V.; Q. Zhou; Veld, A.J. Huis In ‘t

    2012-01-01

    Fluidic self-alignment of micro-components relies on creating a receptor site that is able to confine a liquid droplet. When a micro-component is brought in contact with the droplet, capillary forces move the component to its final position. A method to stop the advancing of a liquid from a receptor site, consists of creating geometrical features, such as edges around the site. A picosecond pulsed laser source was used to create suitable edges in a metallic and a polyimide substrate. Subseque...

  2. Direct Metal Deposition of H13 Tool Steel on Copper Alloy Substrate: Parametric Investigation

    Science.gov (United States)

    Imran, M. Khalid; Masood, S. H.; Brandt, Milan

    2015-12-01

    Over the past decade, researchers have demonstrated interest in tribology and prototyping by the laser aided material deposition process. Laser aided direct metal deposition (DMD) enables the formation of a uniform clad by melting the powder to form desired component from metal powder materials. In this research H13 tool steel has been used to clad on a copper alloy substrate using DMD. The effects of laser parameters on the quality of DMD deposited clad have been investigated and acceptable processing parameters have been determined largely through trial-and-error approaches. The relationships between DMD process parameters and the product characteristics such as porosity, micro-cracks and microhardness have been analysed using scanning electron microscope (SEM), image analysis software (ImageJ) and microhardness tester. It has been found that DMD parameters such as laser power, powder mass flow rate, feed rate and focus size have an important role in clad quality and crack formation.

  3. Oxidation stress evolution and relaxation of oxide film/metal substrate system

    Science.gov (United States)

    Dong, Xuelin; Feng, Xue; Hwang, Keh-Chih

    2012-07-01

    Stresses in the oxide film/metal substrate system are crucial to the reliability of the system at high temperature. Two models for predicting the stress evolution during isothermal oxidation are proposed. The deformation of the system is depicted by the curvature for single surface oxidation. The creep strain of the oxide and metal, and the lateral growth strain of the oxide are considered. The proposed models are compared with the experimental results in literature, which demonstrates that the elastic model only considering for elastic strain gives an overestimated stress in magnitude, but the creep model is consistent with the experimental data and captures the stress relaxation phenomenon during oxidation. The effects of the parameter for the lateral growth strain rate are also analyzed.

  4. The copper spoil heap Knappenberg, Austria, as a model for metal habitats - Vegetation, substrate and contamination.

    Science.gov (United States)

    Adlassnig, Wolfram; Weiss, Yasmin S; Sassmann, Stefan; Steinhauser, Georg; Hofhansl, Florian; Baumann, Nils; Lichtscheidl, Irene K; Lang, Ingeborg

    2016-09-01

    Historic mining in the Eastern Alps has left us with a legacy of numerous spoil heaps hosting specific, metal tolerant vegetation. Such habitats are characterized by elevated concentrations of toxic elements but also by high irradiation, a poorly developed substrate or extreme pH of the soil. This study investigates the distribution of vascular plants, mosses and lichens on a copper spoil heap on the ore bearing Knappenberg formed by Prebichl Layers and Werfener Schist in Lower Austria. It serves as a model for discriminating between various ecological traits and their effects on vegetation. Five distinct clusters were distinguished: (1) The bare, metal rich Central Spoil Heap was only colonised by highly resistant specialists. (2) The Northern and (3) Southern Peripheries contained less copper; the contrasting vegetation was best explained by the different microclimate. (4) A forest over acidic bedrock hosted a vegetation overlapping with the periphery of the spoil heap. (5) A forest over calcareous bedrock was similar to the spoil heap with regard to pH and humus content but hosted a vegetation differing strongly to all other habitats. Among the multiple toxic elements at the spoil heap, only Cu seems to exert a crucial influence on the vegetation pattern. Besides metal concentrations, irradiation, humidity, humus, pH and grain size distribution are important for the establishment of a metal tolerant vegetation. The difference between the species poor Northern and the diverse Southern Periphery can be explained by the microclimate rather than by the substrate. All plant species penetrating from the forest into the periphery of the spoil heap originate from the acidic but not from the calcareous bedrock. PMID:27185350

  5. Modification of opto-electronic properties of ZnO by incorporating metallic tin for buffer layer in thin film solar cells

    International Nuclear Information System (INIS)

    In this report, the effect of incorporation of metallic tin (Sn) on opto-electronic properties of ZnO thin films is presented. ZnO thin films were deposited through ‘automated chemical spray pyrolysis’ (CSP) technique; later different quantities of ‘Sn’ were evaporated on it and subsequently annealed. Vacuum annealing showed a positive effect on crystallinity of films. Creation of sub band gap levels due to ‘Sn’ diffusion was evident from the absorption and PL spectra. The tin incorporated films showed good photo response in visible region. Tin incorporated ZnO thin films seem to satisfy the desirable criteria for buffer layer in thin film solar cells

  6. Modification of opto-electronic properties of ZnO by incorporating metallic tin for buffer layer in thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Deepu, D. R.; Jubimol, J.; Kartha, C. Sudha; Louis, Godfrey; Vijayakumar, K. P., E-mail: kpv@cusat.ac.in [Department of Physics, Cochin University of Science and Technology, Cochin-682022 (India); Kumar, K. Rajeev [Department of Instrumentation, Cochin University of Science and Technology, Cochin-682022 (India)

    2015-06-24

    In this report, the effect of incorporation of metallic tin (Sn) on opto-electronic properties of ZnO thin films is presented. ZnO thin films were deposited through ‘automated chemical spray pyrolysis’ (CSP) technique; later different quantities of ‘Sn’ were evaporated on it and subsequently annealed. Vacuum annealing showed a positive effect on crystallinity of films. Creation of sub band gap levels due to ‘Sn’ diffusion was evident from the absorption and PL spectra. The tin incorporated films showed good photo response in visible region. Tin incorporated ZnO thin films seem to satisfy the desirable criteria for buffer layer in thin film solar cells.

  7. Dispersion of plasmon polaritons guided by a metal film of finite width deposited on a uniaxial substrate

    International Nuclear Information System (INIS)

    We discuss the propagation characteristics of surface plasmon modes supported by a thin lossy metal film of finite width deposited on a uniaxially anisotropic substrate, numerically evaluated using the method of lines. The metal film with finite width (strip waveguide) has been a subject of intensive study, both theoretically and experimentally, since it is the platform of choice for constructing plasmon circuits for optoelectronic integration, over the past few years. Plasmon waveguides with anisotropic dielectric environment have gained importance in research recently. Specifically, artificial substrate materials with strong anisotropy have been proposed as a means of improving the propagation range of plasmon polaritons in wide metal films. In our investigation, it is observed that the anisotropic nature of the substrate removes the degeneracy of the fundamental pair modes which are degenerate in an asymmetric strip waveguide with isotropic substrates.

  8. Composition-dependent electrical properties of (Pb, La)(Zr, Sn, Ti)O3 antiferroelectric thin films grown on platinum-buffered silicon substrates

    International Nuclear Information System (INIS)

    (Pb, La)(Zr, Sn, Ti)O3 (PLZST) antiferroelectric (AFE) thin films with different compositions were deposited on Pt-buffered silicon wafers by the sol-gel process. The phase structure and the surface morphology of the PLZST AFE thin films were analysed by XRD and SEM, respectively. The electric field induced AFE-to-ferroelectric (AFE-FE) phase transformation behaviour of the PLZST thin films was examined by polarization versus field (P-E) and relative permittivity versus field (εr-E) measurements, with emphasis placed on composition-dependent phase switching field. The phase switching current was investigated as a function of a gradually changed dc electric field. Furthermore, the effect of the composition of the PLZST thin films on the Curie temperature (Tc) was also studied in detail

  9. Effect of process pressure and substrate temperature on CdS buffer layers deposited by using RF sputtering for Cu(In,Ga)Se2 solar cells

    Science.gov (United States)

    Choi, Ji Hyun; Jung, Sung Hee; Chung, Chee Won

    2016-02-01

    The characteristics of CdS films deposited on Cu(In,Ga)Se2(CIGS)/Mo/glass and glass substrates by using RF magnetron sputtering were investigated. The deposition pressure and the substrate temperature were selected as key parameters to examine the electrical, compositional and optical properties of the films. As the deposition pressure was increased, the resistivity increased while the carrier concentration decreased owing to a stoichiometric change and Cd-O incorporation at high pressure. Field-emission scanning electron microscopy(FE-SEM) revealed that the CdS films on CIGS/Mo became denser as the pressure was increased, which was responsible for the high transmittance of the film deposited at high pressure. As the substrate temperature was increased, the deposition rate decreased, which could be explained by using Langmuir theory. As the temperature was increased from room temperature to 573 K, the resistivity increased and the carrier concentration decreased, which was attributed to an increase in [S]/[Cd] ratio. In addition, as the temperature was increased, the small grains were agglomerated to form larger grains due to the increase in the activity of grains at high temperature. CdS films were confirmed to be uniformly deposited on the CIGS layer by using RF sputtering. The large amount of interdiffusion between the CIGS and the CdS films deposited at a high substrate temperature were observed by using X-ray photoelectron spectroscopy.

  10. Interfacial Structure and Photocatalytic Activity of Magnetron Sputtered TiO2 on Conducting Metal Substrates

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Petit, Jean-Pierre; Mermoux, Michel;

    2014-01-01

    using X-ray diffraction, Raman spectroscopy, atomic force microscope, and scanning and transmission electron microscopy. Photocatalytic behavior of the coating was explored by using optical spectrophotometry and electrochemical methods via photovoltage, photocurrent, and scanning kelvin probe microscopy......The photocatalytic behavior of magnetron sputtered anatase TiO2 coatings on copper, nickel, and gold was investigated with the aim of understanding the effect of the metallic substrate and coating-substrate interface structure. Stoichiometry and nanoscale structure of the coating were investigated...... measurements. The nature of the metal substrate and coating-substrate interface had profound influence on the photocatalytic behavior. Less photon energy was required for TiO2 excitation on a nickel substrate, whereas TiO2 coating on copper showed a higher band gap attributed to quantum confinement. However...

  11. Back contact to film silicon on metal for photovoltaic cells

    Science.gov (United States)

    Branz, Howard M.; Teplin, Charles; Stradins, Pauls

    2013-06-18

    A crystal oriented metal back contact for solar cells is disclosed herein. In one embodiment, a photovoltaic device and methods for making the photovoltaic device are disclosed. The photovoltaic device includes a metal substrate with a crystalline orientation and a heteroepitaxial crystal silicon layer having the same crystal orientation of the metal substrate. A heteroepitaxial buffer layer having the crystal orientation of the metal substrate is positioned between the substrate and the crystal silicon layer to reduce diffusion of metal from the metal foil into the crystal silicon layer and provide chemical compatibility with the heteroepitaxial crystal silicon layer. Additionally, the buffer layer includes one or more electrically conductive pathways to electrically couple the crystal silicon layer and the metal substrate.

  12. Investigation of Dissolution Behavior of Metallic Substrates and Intermetallic Compound in Molten Lead-free Solders

    Science.gov (United States)

    Yen, Yee-Wen; Chou, Weng-Ting; Tseng, Yu; Lee, Chiapyng; Hsu, Chun-Lei

    2008-01-01

    This study investigates the dissolution behavior of the metallic substrates Cu and Ag and the intermetallic compound (IMC)-Ag3Sn in molten Sn, Sn-3.0Ag-0.5Cu, Sn-58Bi and Sn-9Zn (in wt.%) at 300, 270 and 240°C. The dissolution rates of both Cu and Ag in molten solder follow the order Sn > Sn-3.0Ag-0.5Cu >Sn-58Bi > Sn-9Zn. Planar Cu3Sn and scalloped Cu6Sn5 phases in Cu/solders and the scalloped Ag3Sn phase in Ag/solders are observed at the metallic substrate/solder interface. The dissolution mechanism is controlled by grain boundary diffusion. The planar Cu5Zn8 layer formed in the Sn-9Zn/Cu systems. AgZn3, Ag5Zn8 and AgZn phases are found in the Sn-9Zn/Ag system and the dissolution mechanism is controlled by lattice diffusion. Massive Ag3Sn phases dissolved into the solders and formed during solidification processes in the Ag3Sn/Sn or Sn-3.0Ag-0.5Cu systems. AgZn3 and Ag5Zn8 phases are formed at the Sn-9Zn/Ag3Sn interface. Zn atoms diffuse through Ag-Zn IMCs to form (Ag, Zn)Sn4 and Sn-rich regions between Ag5Zn8 and Ag3Sn.

  13. Long-range wetting transparency on top of layered metal-dielectric substrates

    Science.gov (United States)

    Noginov, M. A.; Barnakov, Yuri A.; Liberman, Vladimir; Prayakarao, Srujana; Bonner, Carl E.; Narimanov, Evgenii E.

    2016-06-01

    It has been recently shown that scores of physical and chemical phenomena (including spontaneous emission, scattering and Förster energy transfer) can be controlled by nonlocal dielectric environments provided by metamaterials with hyperbolic dispersion and simpler metal/dielectric structures. At this time, we have researched van der Waals interactions and experimentally studied wetting of several metallic, dielectric and composite multilayered substrates. We have found that the wetting angle of water on top of MgF2 is highly sensitive to the thickness of the MgF2 layer and the nature of the underlying substrate that could be positioned as far as ~100 nm beneath the water/MgF2 interface. We refer to this phenomenon as long range wetting transparency. The latter effect cannot be described in terms of the most basic model of dispersion van der Waals-London forces based on pair-wise summation of dipole-dipole interactions across an interface or a gap separating the two media. We infer that the experimentally observed gradual change of the wetting angle with increase of the thickness of the MgF2 layer can possibly be explained by the distance dependence of the Hamaker function (describing the strength of interaction), which originates from retardation of electromagnetic waves at the distances comparable to a wavelength.

  14. Greatly Enhancing Catalytic Activity of Graphene by Doping the Underlying Metal Substrate.

    Science.gov (United States)

    Guo, Na; Xi, Yongjie; Liu, Shuanglong; Zhang, Chun

    2015-01-01

    Graphene-based solid-state catalysis represents a new direction in applications of graphene and has attracted a lot of interests recently. However, the difficulty in fine control and large-scale production of previously proposed graphene catalysts greatly limits their industrial applications. Here we present a novel way to enhance the catalytic activity of graphene, which is highly efficient yet easy to fabricate and control. By first-principles calculations, we show that when the underlying metal substrate is doped with impurities, the catalytic activity of the supported graphene can be drastically enhanced. Graphene supported on a Fe/Ni(111) surface is chosen as a model catalyst, and the chemical reaction of CO oxidation is used to probe the catalytic activity of graphene. When the underlying Fe/Ni(111) substrate is impurity free, the graphene is catalytically inactive. When a Zn atom is doped into the substrate, the catalytic activity of the supported graphene is greatly enhanced, and the reaction barrier of the catalyzed CO oxidation is reduced to less than 0.5 eV. Intriguing reaction mechanism of catalyzed CO oxidation is revealed. These studies suggest a new class of graphene-based catalysts and pave the way for future applications of graphene in solid-state catalysis. PMID:26156332

  15. Evaluation and Characterization of Plasma Sprayed Cu Slag-Al Composite Coatings on Metal Substrates

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2013-01-01

    Full Text Available Copper slag is a waste product obtained during matte smelting and refining of copper. The present work explores the coating potential of copper slag by plasma spraying. This work shows that copper slag is eminently coatable. An attempt has been made in the present investigation to use the composites coatings of copper slag and Al powder in suitable combination on aluminium and mild steel substrates in order to improve the surface properties of these ductile metal-alloy substrates. When premixed with Al powder, the coating exhibits higher interfacial adhesion as compared to pure copper slag coatings. Maximum adhesion strengths of about 23 MPa and 21 MPa are recorded for the coatings of copper slag with 15 wt% of Al on aluminium and mild steel substrates, respectively. The input power to the plasma torch is found to affect the coating deposition efficiency and morphology of the coatings. It also suggests value addition of an industrial waste.

  16. Active vacuum brazing of CNT films to metal substrates for superior electron field emission performance

    International Nuclear Information System (INIS)

    The joining of macroscopic films of vertically aligned multiwalled carbon nanotubes (CNTs) to titanium substrates is demonstrated by active vacuum brazing at 820 °C with a Ag–Cu–Ti alloy and at 880 °C with a Cu–Sn–Ti–Zr alloy. The brazing methodology was elaborated in order to enable the production of highly electrically and thermally conductive CNT/metal substrate contacts. The interfacial electrical resistances of the joints were measured to be as low as 0.35 Ω. The improved interfacial transport properties in the brazed films lead to superior electron field-emission properties when compared to the as-grown films. An emission current of 150 μA was drawn from the brazed nanotubes at an applied electric field of 0.6 V μm−1. The improvement in electron field-emission is mainly attributed to the reduction of the contact resistance between the nanotubes and the substrate. The joints have high re-melting temperatures up to the solidus temperatures of the alloys; far greater than what is achievable with standard solders, thus expanding the application potential of CNT films to high-current and high-power applications where substantial frictional or resistive heating is expected. (paper)

  17. Nanotribological properties of water films adsorbing atop, and absorbing below, graphene layers supported by metal substrates

    Science.gov (United States)

    Liu, Zijian; Curtis, C. K.; Stine, R.; Sheehan, P.; Krim, J.

    The tribological properties of graphite, a common lubricant with known sensitivity to the presence of water, have been studied extensively at the macroscopic and microscopic scales. Although far less attention has been devoted to the tribological properties of graphene, it has been established that the tribological response to the presence of water is dissimilar from that of graphite. We report here a quartz crystal microbalance study of the nanotribological properties of water films adsorbed/absorbed on graphene layers prepared by either chemical decomposition on nickel(111) substrates or transfer of freestanding graphene layers to aluminum substrates. Sliding friction levels of the water films were also measured for metal surfaces in the absence of a graphene layer. We observe very high friction levels for water adsorbed atop graphene on Ni(111) and very low levels for water on aluminum. For the case of graphene/aluminum, the data indicate that the water is absorbing between the graphene layer and the aluminum. Dissipation levels moreover indicate the presence of an interstitial water increases sliding friction between the graphene and the aluminum substrate Work supported by NSF and NRL.

  18. Laser-induced spalling of thin metal film from silica substrate followed by inflation of microbump

    Science.gov (United States)

    Inogamov, N. A.; Zhakhovsky, V. V.; Migdal, K. P.

    2016-04-01

    Dynamics of a thin gold film on a silica substrate triggered by fast heating with the use of a subpicosecond laser pulse is studied. The pressure waves generated by such heating may result in spalling (delamination) of the film and its flying away from the substrate after an acoustic time defined by the film thickness and speed of sound in metal. Intensity of the heating laser beam has the spatial Gaussian distribution in a cross section. Therefore, the heating of film surface is non-uniform along cylindrical radius measured from the beam axis. As a result of such heating, the velocity distribution in material flying away from the substrate has a maximum at the beam axis. Thus, the separated film has dome-like shape which inflates with time. Volume of an empty cavity between the separated film and the substrate increases during inflation. Typical flight velocities are in the range of 30-200 m/s. The inflation stage can last from few to several tens of nanoseconds if the diffraction-limited micron-sized laser focal spots are used. Capillary forces acting along the warped flying film decelerate the inflation of dome. Capillary deceleration of a bulging dome focuses mass flow along the dome shell in the direction of its axis. This results in formation of an axial jet and droplet in a tip of the dome. Our new simulation results and comparisons with experiments are presented. The results explain appearance of debris in a form of frozen droplets on a surface of an irradiated spot. This is the consequence of the capillary return of a droplet.

  19. Effect of a dielectric substrate with a subwavelength thickness on light diffraction by rectangular hole arrays on metallic film

    Energy Technology Data Exchange (ETDEWEB)

    Park, D. J.; Jeong, M. S. [Sungkyunkwan University, Suwon (Korea, Republic of); Choi, S. B. [Incheon National University, Incheon (Korea, Republic of)

    2014-11-15

    A theoretical study of the effect of ultrathin dielectric substrate in THz wave diffraction phenomena on a subwavelength nanostructured system is conducted. The proposed system is composed of a dielectric substrate with a thickness of ∼ λ/1000 and a subwavelength-scaled rectangular hole array on a metal thin film in THz wavelength region. A modified Rayleigh diffraction theory has been developed to take into account the contribution of reflection at the air-substrate interface. A calculation of the terahertz transmission while varying the thickness shows that the effect of a thin dielectric substrate starts to vanish when the thickness becomes ∼1/100 of the incident light's wavelength. Theoretically, the results are well explained because most electric fields are confined near the rectangular aperture, which results in the dominant existence of the field inside the thin substrate. Additionally, the effect of a thin dispersive substrate is discussed.

  20. Mechanical strength and tribological behavior of ion-beam deposited boron nitride films on non-metallic substrates

    International Nuclear Information System (INIS)

    An investigation was conducted to examine the mechanical strength and tribological properties of boron nitride (BN) films ion-beam deposited on silicon (Si), fused silica (SiO2), gallium arsenide (GaAs), and indium phosphide (InP) substrates in sliding contact with a diamond pin under a load. The results of the investigation indicate that BN films on nonmetallic substrates, like metal films on metallic substrates, deform elastically and plastically in the interfacial region when in contact with a diamond pin. However, unlike metal films and substrates, BN films on nonmetallic substrates can fracture when they are critically loaded. Not only does the yield pressure (hardness) of Si and SiO2 substrates increase by a factor of 2 in the presence of a BN film, but the critical load needed to fracture increases as well. The presence of films on the brittle substrates can arrest crack formation. The BN film reduces adhesion and friction in the sliding contact. BN adheres to Si and SiO2 and forms a good quality film, while it adheres poorly to GaAs and InP. The interfacial adhesive strengths were 1 GPa for a BN film on Si and appreciably higher than 1 GPa for a BN film on SiO2

  1. Nanoscale “Quantum” Islands on Metal Substrates: Microscopy Studies and Electronic Structure Analyses

    Directory of Open Access Journals (Sweden)

    Da-Jiang Liu

    2010-07-01

    Full Text Available Confinement of electrons can occur in metal islands or in continuous films grown heteroepitaxially upon a substrate of a different metal or on a metallic alloy. Associated quantum size effects (QSE can produce a significant height-dependence of the surface free energy for nanoscale thicknesses of up to 10–20 layers. This may suffice to induce height selection during film growth. Scanning STM analysis has revealed remarkable flat-topped or mesa-like island and film morphologies in various systems. We discuss in detail observations of QSE and associated film growth behavior for Pb/Cu(111, Ag/Fe(100, and Cu/fcc-Fe/Cu(100 [A/B or A/B/A], and for Ag/NiAl(110 with brief comments offered for Fe/Cu3Au(001 [A/BC binary alloys]. We also describe these issues for Ag/5-fold i-Al-Pd-Mn and Bi/5-fold i-Al-Cu-Fe [A/BCD ternary icosohedral quasicrystals]. Electronic structure theory analysis, either at the level of simple free electron gas models or more sophisticated Density Functional Theory calculations, can provide insight into the QSE-mediated thermodynamic driving force underlying height selection.

  2. Corrosion resistance of Ni-50Cr HVOF coatings on 310S alloy substrates in a metal dusting atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Saaedi, J. [Centre for Advanced Coating Technologies, Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4 (Canada); Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Arabi, H.; Mirdamadi, S.; Ghorbani, H. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Coyle, T.W. [Centre for Advanced Coating Technologies, Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4 (Canada)

    2011-09-15

    Metal dusting attack has been examined after three 168 h cycles on two Ni-50Cr coatings with different microstructures deposited on 310S alloy substrates by the high velocity oxy-fuel (HVOF) thermal-spray process. Metal dusting in uncoated 310S alloy specimens was found to be still in the initiation stage after 504 h of exposure in the 50H{sub 2}:50CO gas environment at 620 C. Dense Ni-50Cr coatings offered suitable resistance to metal dusting. Metal dusting was observed in the 310S substrates adjacent to pores at the interface between the substrate and a porous Ni-50Cr coating. The porosity present in the as-deposited coatings was shown to introduce a large variability into coating performance. Carbon formed by decomposition of the gaseous species accumulated in the surface pores and resulted in the dislodgement of surface splats due to stresses generated by the volume changes. When the corrosive gas atmosphere was able to penetrate through the interconnected pores and reach the coating-substrate interface, the 310S substrate was carburized, metal dusting attack occurred, and the resulting formation of coke in the pores led to local failure of the coating. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Epitaxial growth of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} on Ni{sub 89}V{sub 11} non-magnetic biaxially textured substrate using NiO as buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Boffa, V. [ENEA, Centro Ricerche Frascati, Via E. Fermi, 45, 00044 Frascati, Rome (Italy). E-mail: boffa at frascati.enea.it; Petrisor, T.; Celentano, G.; Fabbri, F.; Annino, C.; Ciontea, L.; Galluzzi, V.; Gambardella, U.; Grimaldi, G.; Mancini, A. [ENEA, Centro Ricerche Frascati, Via E. Fermi, 45, 00044 Frascati, Rome (Italy); Ceresara, S. [CNR-TEMPE, C.so Promessi Sposi, 29, 22053 Lecco (Italy)

    2000-10-01

    The superconducting YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}/CeO{sub 2}/NiO multilayer structure was grown in situ by pulsed-laser deposition on biaxially textured Ni{sub 89}V{sub 11} non-magnetic alloy. The role of vanadium is to decrease the Curie temperature of Ni and to favour the formation of oriented NiO. The (00l)NiO buffer layer has been formed by the controlled oxidation of the Ni-V substrate under 10 mTorr oxygen pressure and at 700 deg. C. The critical current density of 0.6 MA cm{sup -2}, at 77 K and zero magnetic field, was obtained for 0.7 {mu}m thick YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} films. (author)

  4. Influence of buffer-layer construction and substrate orientation on the electron mobilities in metamorphic In0.70Al0.30As/In0.76Ga0.24As/In0.70Al0.30As structures on GaAs substrates

    International Nuclear Information System (INIS)

    The influence of construction of the buffer layer and misorientation of the substrate on the electrical properties of In0.70Al0.30As/In0.76Ga0.24As/In0.70Al0.30As quantum wells on a GaAs substrate is studied. The temperature dependences (in the temperature range of 4.2 K < T < 300 K) and field dependences (in magnetic fields as high as 6 T) of the sample resistances are measured. Anisotropy of the resistances in different crystallographic directions is detected; this anisotropy depends on the substrate orientation and construction of the metamorphic buffer layer. In addition, the Hall effect and the Shubnikov–de Haas effect are studied. The Shubnikov–de Haas effect is used to determine the mobilities of electrons separately in several occupied dimensionally quantized subbands in different crystallographic directions. The calculated anisotropy of mobilities is in agreement with experimental data on the anisotropy of the resistances

  5. Semiconductor films on flexible iridium substrates

    Science.gov (United States)

    Goyal, Amit

    2005-03-29

    A laminate semiconductor article includes a flexible substrate, an optional biaxially textured oxide buffer system on the flexible substrate, a biaxially textured Ir-based buffer layer on the substrate or the buffer system, and an epitaxial layer of a semiconductor. Ir can serve as a substrate with an epitaxial layer of a semiconductor thereon.

  6. Radio frequency surface resistance of Tl-Ba-Ca-Cu-O films on metal and single-crystal substrates

    Science.gov (United States)

    Arendt, P. N.; Reeves, G. A.; Elliott, N. E.; Cooke, D. W.; Gray, E. R.; Houlton, R. J.; Brown, D. R.

    1990-01-01

    Films of Tl-Ba-Ca-Cu were dc magnetron sputtered from a single multielement target. The films were deposited onto substrates of: (1) magnesium oxide, (2) a silver based alloy (Consil 995), (3) a nickel based alloy (Haynes 230), and (4) buffer layers of barium fluoride or copper oxide on Consil. To form superconducting phases, post-deposition anneals were made on these films using an alumina crucible with an over pressure of thallium and flowing oxygen. After annealing, the film phases were determined using x-ray diffraction. The film surface resistances (Rs) were measured at 22 GHz in a TE011 cavity.

  7. Integrated pinning centers in YBa2Cu3Ox thick films on single-crystalline and textured metal substrates

    International Nuclear Information System (INIS)

    The second-generation coated tapes of high temperature superconductors (HTS) deposited on textured metal substrates strongly rely on the introduction of extended nano-defects in order to enhance their critical current. A proven effective way to introduce such defects is growing BaZrO3 (BZO) nano-rods and an alternative way is to generate HTS columnar growth using nanoparticles of noble metals. Here we report the combination of these methods. It allows achieving controlled pinning and high critical current in YBa2Cu3Ox films deposited on single crystal substrates and significantly improves critical current in coated conductors deposited on rolling-assisted biaxially-textured metal substrates (RABiTS). The superconducting properties of thick (up to 5 micron) conductors are analysed using DC-magnetisation, AC-susceptibility and angle-dependent transport measurements. TEM imaging is used to confirm the presence of extended defects in the tapes.

  8. Modifying the characteristics of carbon nanotubes grown on metallic substrates for ultracapacitor applications

    International Nuclear Information System (INIS)

    This paper reports the design, fabrication, and testing of carbon nanotube (CNT)-based ultracapacitor electrodes and provides quantitative results, showing that total electrode surface area—and, correspondingly, the total cell capacitance—is highly sensitive to the amount of catalyst material deposited prior to CNT growth. We deposit between 0.6 and 1.0 nm of iron catalyst on metallic (tungsten) substrates and synthesized vertically aligned CNT forests directly by thermal chemical vapor deposition. A capacitance maximum is observed with electrodes prepared with 0.8 nm of catalyst. Geometrical arguments based on average CNT diameter and areal density are used to corroborate this result. The CNTs' differential capacitance is found to be independent of their areal density, mean diameter, length, and the amount of catalyst used to grow them.

  9. Modifying the characteristics of carbon nanotubes grown on metallic substrates for ultracapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Jenicek, D. P., E-mail: djenicek@mit.edu; Kassakian, J. G. [Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); McCarthy, A. [Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-05-28

    This paper reports the design, fabrication, and testing of carbon nanotube (CNT)-based ultracapacitor electrodes and provides quantitative results, showing that total electrode surface area—and, correspondingly, the total cell capacitance—is highly sensitive to the amount of catalyst material deposited prior to CNT growth. We deposit between 0.6 and 1.0 nm of iron catalyst on metallic (tungsten) substrates and synthesized vertically aligned CNT forests directly by thermal chemical vapor deposition. A capacitance maximum is observed with electrodes prepared with 0.8 nm of catalyst. Geometrical arguments based on average CNT diameter and areal density are used to corroborate this result. The CNTs' differential capacitance is found to be independent of their areal density, mean diameter, length, and the amount of catalyst used to grow them.

  10. Deposition and STM characterization of luminescent organic molecules on metal substrates

    International Nuclear Information System (INIS)

    The porphyrin-based molecules including H2TBPP, ZnTBPP and PtTBPP as well as the perinone derivatives (PD) molecules were deposited on Au(100), Au(111) and Cu(100) substrates in the form of single molecule, molecular line, submonolayer, monolayer and multilayer. The features of the performed molecular nanostructures were characterized by an ultrahigh vacuum scanning tunneling microscopy (STM) at room temperature. The observed molecular topographies matched very well with the molecule structures in spite of the fact that the molecular adsorption states were influenced by different metal surface. STM-induced photon emission was generated from the surface of H2TBPP multilayer structures on Au(100) in tunneling junction when the applied bias exceeds the 'turn-on' voltages ∼- 1.6 V or + 1.3 V at 0.5 nA

  11. Aluminum clad ferritic stainless steel foil for metallic catalytic converter substrate applications

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.S.; Pandey, A.; Jha, B.

    1996-09-01

    A roll bonding process was developed to produce Al clad ferritic stainless steel foil for the metallic catalytic converter substrate application. Clad foils with different chemistry were produced and their properties were evaluated. Heat treatment conditions for the homogenization of clad foils were identified. This article includes results from oxidation tests and mechanical tests on as-rolled and heat treated clad foil. Results from commercial ingot metallurgy foil were also included for comparison. The oxidation weight gain study indicates that the Al content in the foils is directly related to the usable life of the foil. However, rare earth addition is necessary to improve the oxidation resistance of this material for the high temperature applications by slowing down the weight gain kinetics and thus extend the usable life of foils. The heat treated clad foil also exhibit excellent tensile ductility when compared to the ingot metallurgy foil.

  12. Composite anodes based on nanotube titanium oxide from electro-oxidation of Ti metal substrate

    Science.gov (United States)

    Pozio, A.; Carewska, M.; Mura, F.; D'Amato, R.; Falconieri, M.; De Francesco, M.; Appetecchi, G. B.

    2014-02-01

    In this manuscript is reported an investigation on lithium-ion battery composite anodes based on nanotube titanium oxide active material obtained from electrochemical oxidation of titanium metal substrates. Nanotube TiO2 showed a good nominal capacity, particularly taking into account that no electronic conductive additive as well as no binder was incorporated into the TiO2 material. The performance of nanotube titanium oxide anode tapes was compared with that of electrodes based on TiO2 both commercially available and obtained from laser pyrolysis. Cycling tests have indicated that the anodes based on electrosynthesized nanotube TiO2 exhibit the best performance in terms of capacity values and rate capability in combination with very good capacity retention and coulombic efficiency leveling 100% even at high rates.

  13. Analysis of the Micromachining Process of Dielectric and Metallic Substrates Immersed in Water with Femtosecond Pulses

    Directory of Open Access Journals (Sweden)

    Simas Butkus

    2015-12-01

    Full Text Available Micromachining of 1 mm thick dielectric and metallic substrates was conducted using femtosecond pulse generated filaments in water. Several hundred microjoule energy pulses were focused within a water layer covering the samples. Within this water layer, non-linear self-action mechanisms transform the beam, which enables higher quality and throughput micromachining results compared to focusing in air. Evidence of beam transformation into multiple light filaments is presented along with theoretical modeling results. In addition, multiparametric optimization of the fabrication process was performed using statistical methods and certain acquired dependencies are further explained and tested using laser shadowgraphy. We demonstrate that this micromachining process exhibits complicated dynamics within the water layer, which are influenced by the chosen parameters.

  14. Electrodeposition of metallic tungsten coating from binary oxide molten salt on low activation steel substrate

    International Nuclear Information System (INIS)

    Tungsten is considered a promising plasma facing armor material for future fusion devices. An electrodeposited metallic tungsten coating from Na2WO4–WO3 binary oxide molten salt on low activation steel (LAS) substrate was investigated in this paper. Tungsten coatings were deposited under various pulsed currents conditions at 1173 K in atmosphere. Cathodic current density and pulsed duty cycle were investigated for pulsed current electrolysis. The crystal structure and microstructure of tungsten coatings were characterized by X-ray diffractometry, scanning electron microscopy, and energy X-ray dispersive analysis techniques. The results indicated that pulsed current density and duty cycle significantly influence tungsten nucleation and electro-crystallization phenomena. The average grain size of the coating becomes much larger with increasing cathodic current density, which demonstrates that appropriate high cathodic current density can accelerate the growth of grains on the surface of the substrate. The micro-hardness of tungsten coatings increases with the increasing thickness of coatings; the maximum micro-hardness is 482 HV. The prepared tungsten coatings have a smooth surface, a porosity of less than 1%, and an oxygen content of 0.024 wt%

  15. In-situ wafer bowing measurements of GaN grown on Si (111) substrate by reflectivity mapping in metal organic chemical vapor deposition system

    Science.gov (United States)

    Yang, Yi-Bin; Liu, Ming-Gang; Chen, Wei-Jie; Han, Xiao-Biao; Chen, Jie; Lin, Xiu-Qi; Lin, Jia-Li; Luo, Hui; Liao, Qiang; Zang, Wen-Jie; Chen, Yin-Song; Qiu, Yun-Ling; Wu, Zhi-Sheng; Liu, Yang; Zhang, Bai-Jun

    2015-09-01

    In this work, the wafer bowing during growth can be in-situ measured by a reflectivity mapping method in the 3×2″ Thomas Swan close coupled showerhead metal organic chemical vapor deposition (MOCVD) system. The reflectivity mapping method is usually used to measure the film thickness and growth rate. The wafer bowing caused by stresses (tensile and compressive) during the epitaxial growth leads to a temperature variation at different positions on the wafer, and the lower growth temperature leads to a faster growth rate and vice versa. Therefore, the wafer bowing can be measured by analyzing the discrepancy of growth rates at different positions on the wafer. Furthermore, the wafer bowings were confirmed by the ex-situ wafer bowing measurement. High-resistivity and low-resistivity Si substrates were used for epitaxial growth. In comparison with low-resistivity Si substrate, GaN grown on high-resistivity substrate shows a larger wafer bowing caused by the highly compressive stress introduced by compositionally graded AlGaN buffer layer. This transition of wafer bowing can be clearly in-situ measured by using the reflectivity mapping method. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274039 and 51177175), the National Basic Research Program of China (Grant No. 2011CB301903), the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20110171110021), the International Science and Technology Collaboration Program of China (Grant No. 2012DFG52260), the International Science and Technology Collaboration Program of Guangdong Province, China (Grant No. 2013B051000041), the Science and Technology Plan of Guangdong Province, China (Grant No. 2013B010401013), the National High Technology Research and Development Program of China (Grant No. 2014AA032606), and the Opened Fund of the State Key Laboratory on Integrated Optoelectronics, China (Grant No. IOSKL2014KF17).

  16. Metal nanoparticle-doped coloured films on glass and polycarbonate substrates

    Indian Academy of Sciences (India)

    S K Medda; M Mitra; S De; S Pal; G De

    2005-11-01

    In a program on the development of metal (e.g. Au, Ag, Cu and their alloy) nanoparticles in sol{gel derived films, attempts were made to synthesize different coloured coatings on glasses and plastics. The absorption position of surface plasmon resonance (SPR) band arising from the embedded metal nanoparticles was tailored by controlling the refractive index of the matrix for the development of different colours. Thus different coloured (pink to blue) coatings on ordinary sheet glasses were prepared by generating Au nanoparticles in mixed SiO2-TiO2 matrices having refractive index values ranging from about 1.41 to 1.93. In another development, in situ generation of Ag nanoparticles in the inorganic{organic hybrid host leads to the formation of different abrasion resistant coloured coatings (yellow to pink) on polycarbonate substrates after curing. As expected, the SPR peak of Ag or Au is gradually red-shifted due to the increase of refractive index of the coating matrices causing a systematic change of colour.

  17. Crack-free micromachining on glass substrates by visible LIBWE using liquid metallic absorbers

    International Nuclear Information System (INIS)

    Laser induced backside wet etching (LIBWE) is a promising laser direct-write technique for etching transparent materials and for producing high precision and near-optical quality surfaces. In this study, visible LIBWE using gallium and eutectic indium/gallium as absorbers was used for crack-free microfabrication of sodalime and quartz. Eutectic indium/gallium (In/Ga) has a melting temperature lower than metallic gallium does and the etching rate by using In/Ga was found to be similar to that by gallium for visible LIBWE. When using the gallium absorber, the etching threshold of quartz by visible LIBWE was about one-third of that by UV LIBWE. The heat-affected zone of the quartz etching was negligible at the trench rim in the visible LIBWE process. The wettability of the metallic absorbers on the substrates affects aspect ratio and is a new important factor for LIBWE. In addition, etching rate decreased when repetition rate was increased.

  18. Crack-free micromachining on glass substrates by visible LIBWE using liquid metallic absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Yen, Meng-Hua; Huang, Ching-Wen [Institute of Biomedical Engineering, National Taiwan University, Taiwan (China); Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan (China); Hsu, Wen-Chi [Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan (China); Young, Tai-Horng [Institute of Biomedical Engineering, National Taiwan University, Taiwan (China); Zimmer, Klaus [Leibniz Institute of Surface Modification, Leipzig (Germany); Cheng, Ji-Yen, E-mail: jycheng@gate.sinica.edu.tw [Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan (China); Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Taiwan (China); Institute of Biophotonics, National Yang-Ming University, Taiwan (China)

    2010-10-15

    Laser induced backside wet etching (LIBWE) is a promising laser direct-write technique for etching transparent materials and for producing high precision and near-optical quality surfaces. In this study, visible LIBWE using gallium and eutectic indium/gallium as absorbers was used for crack-free microfabrication of sodalime and quartz. Eutectic indium/gallium (In/Ga) has a melting temperature lower than metallic gallium does and the etching rate by using In/Ga was found to be similar to that by gallium for visible LIBWE. When using the gallium absorber, the etching threshold of quartz by visible LIBWE was about one-third of that by UV LIBWE. The heat-affected zone of the quartz etching was negligible at the trench rim in the visible LIBWE process. The wettability of the metallic absorbers on the substrates affects aspect ratio and is a new important factor for LIBWE. In addition, etching rate decreased when repetition rate was increased.

  19. Laser Induced Reverse Transfer with metal and hybrid material prepared with sol–gel process used on glass substrate

    International Nuclear Information System (INIS)

    This article presents a possible use of Laser Induced Reverse Transfer (LIRT) for metal deposition combined with hybrid material prepared using the sol–gel process. The goal was to obtain two dimensional metal gratings with inorganic–organic hybrid material protection on low cost glass substrates. The hybrid material using the sol–gel material is employed here to give better adhesion of metal deposited by LIRT on glass substrates, and also to possibly cover the metal structure. The hybrid material was an organically modified silicate glass based on methacryloxypropyltri-methoxysilane (MATPMS) and zirconium propoxide. The proposed process permits to prototype rapidly small diffractive structure in amplitude mode or to mark two dimensional complicated patterns without complex technologies employing a focalized and computer controlled Nd–YAG laser at 1064 nm. The different steps of the technology are also discussed.

  20. Effects of the annealing duration of the ZnO buffer layer on structural and optical properties of ZnO rods grown by a hydrothermal process

    International Nuclear Information System (INIS)

    In this study, the effects of the annealing duration of a zinc oxide (ZnO) buffer layer on structural and optical properties of ZnO rods grown by a hydrothermal process are discussed. A ZnO buffer layer was deposited on p-type Si (1 1 1) substrates by the metal organic chemical vapor deposition (MOCVD) method. After that, ZnO rods were grown on the ZnO-buffer/Si (1 1 1) substrate by a hydrothermal process. In order to determine the optimum annealing duration of the buffer layer for the growth of ZnO rods, durations ranging from 0.5 to 30 min were tried. The morphology and crystal structure of the ZnO/ZnO-buffer/Si (1 1 1) were measured by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The optical properties were investigated by photoluminescence (PL) measurement.

  1. CONTROLLED GROWTH OF CARBON NANOTUBES ON CONDUCTIVE METAL SUBSTRATES FOR ENERGY STORAGE APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.; Engtrakul, C.

    2009-01-01

    The impressive mechanical and electronic properties of carbon nanotubes (CNTs) make them ideally suited for use in a variety of nanostructured devices, especially in the realm of energy production and storage. In particular, vertically-aligned CNT “forests” have been the focus of increasing investigation for use in supercapacitor electrodes and as hydrogen adsorption substrates. Vertically-aligned CNT growth was attempted on metal substrates by waterassisted chemical vapor deposition (CVD). CNT growth was catalyzed by iron-molybdenum (FeMo) nanoparticle catalysts synthesized by a colloidal method, which were then spin-coated onto Inconel® foils. The substrates were loaded into a custom-built CVD apparatus, where CNT growth was initiated by heating the substrates to 750 °C under the fl ow of He, H2, C2H4 and a controlled amount of water vapor. The resultant CNTs were characterized by a variety of methods including Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and the growth parameters were varied in an attempt to optimize the purity and growth yield of the CNTs. The surface area and hydrogen adsorption characteristics of the CNTs were quantifi ed by the Brunauer- Emmett-Teller (BET) and Sieverts methods, and their capacitance was measured via cyclic voltammetry. While vertically-aligned CNT growth could not be verifi ed, TEM and SEM analysis indicated that CNT growth was still obtained, resulting in multiwalled CNTs of a wide range in diameter along with some amorphous carbon impurities. These microscopy fi ndings were reinforced by Raman spectroscopy, which resulted in a G/D ratio ranging from 1.5 to 3 across different samples, suggestive of multiwalled CNTs. Changes in gas fl ow rates and water concentration during CNT growth were not found to have a discernable effect on the purity of the CNTs. The specifi c capacitance of a CNT/FeMo/Inconel® electrode was found to be 3.2 F/g, and the BET surface area of

  2. Substrate Structures For Growth Of Highly Oriented And/Or Epitaxial Layers Thereon

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Paul N. (Los Alamos, NM); Foltyn, Stephen R. (Los Alamos, NM); Groves, James R. (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM)

    2005-07-26

    A composite substrate structure including a substrate, a layer of a crystalline metal oxide or crystalline metal oxynitride material upon the substrate, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the crystalline metal oxide or crystalline metal oxynitride material layer is provided together with additional layers such as one or more layers of a buffer material upon the oriented cubic oxide material layer. Jc's of 2.3×106 A/cm2 have been demonstrated with projected Ic's of 320 Amperes across a sample 1 cm wide for a superconducting article including a flexible polycrystalline metallic substrate, an inert oxide material layer upon the surface of the flexible polycrystalline metallic substrate, a layer of a crystalline metal oxide or crystalline metal oxynitride material upon the layer of the inert oxide material, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the crystalline metal oxide or crystalline metal oxynitride material layer, a layer of a buffer material upon the oriented cubic oxide material layer, and, a top-layer of a high temperature superconducting material upon the layer of a buffer material.

  3. Atomized spraying of liquid metal droplets on desired substrate surfaces as a generalized way for ubiquitous printed electronics

    Science.gov (United States)

    Zhang, Qin; Gao, Yunxia; Liu, Jing

    2014-09-01

    A direct electronics printing technique through atomized spraying for patterning room-temperature liquid metal droplets on desired substrate surfaces is proposed and experimentally demonstrated for the first time. This method is highly flexible and capable of fabricating electronic components on various target objects, with either flat or rough surfaces, made of different materials, or having different orientations from 2D to 3D geometrical configurations. With a pre-designed mask, the liquid metal ink can be directly deposited on the substrate to form various specific patterns which lead to the rapid prototyping of electronic devices. Further, extended printing strategies were also suggested to illustrate the adaptability of the method. For example, it can be used for making transparent conductive film with an optical transmittance of 47 % and a sheet resistance of 5.167Ω/□ due to natural porous structure. Different from the former direct writing technology where large surface tension and poor adhesion between the liquid metal and the substrate often impede the flexible printing process, the liquid metal here no longer needs to be pre-oxidized to guarantee its applicability on target substrates. One critical mechanism was that the atomized liquid metal microdroplets can be quickly oxidized in the air due to its large specific surface area, resulting in a significant increase of the adhesion capacity and thus firm deposition of the ink to the substrate. This study paved a generalized way for pervasively and directly printing electronics on various substrates which are expected to be significant in a wide spectrum of electrical engineering areas.

  4. Microtransfer printing of metal ink patterns onto plastic substrates utilizing an adhesion-controlled polymeric donor layer

    Science.gov (United States)

    Park, Ji-Sub; Choi, Jun-Chan; Park, Min-Kyu; Bae, Jeong Min; Bae, Jin-Hyuk; Kim, Hak-Rin

    2016-06-01

    We propose a method for transfer-printed electrode patterns onto flexible/plastic substrates, specifically intended for metal ink that requires a high sintering temperature. Typically, metal-ink-based electrodes cannot be picked up for microtransfer printing because the adhesion between the electrodes and the donor substrate greatly increases after the sintering process due to the binding materials. We introduced a polymeric donor layer between the printed electrodes and the donor substrate and effectively reduced the adhesion between the Ag pattern and the polymeric donor layer by controlling the interfacial contact area. After completing a wet-etching process for the polymeric donor layer, we obtained Ag patterns supported on the fine polymeric anchor structures; the Ag patterns could be picked up onto the stamp surface even after the sintering process by utilizing the viscoelastic properties of the elastomeric stamp with a pick-up velocity control. The proposed method enables highly conductive metal-ink-based electrode patterns to be applied on thermally weak plastic substrates via an all-solution process. Metal electrodes transferred onto a film showed superior electrical and mechanical stability under the bending stress test required for use in printed flexible electronics.

  5. Thin-Film Solar Cells on Metal Foil Substrates for Space Power

    Science.gov (United States)

    Raffaelle, Ryne P.; Hepp, Aloysius F.; Hoffman, David J.; Dhere, N.; Tuttle, J. R.; Jin, Michael H.

    2004-01-01

    Photovoltaic arrays have played a key role in power generation in space. The current technology will continue to evolve but is limited in the important mass specific power metric (MSP or power/weight ratio) because it is based on bulk crystal technology. The objective of this research is to continue development of an innovative photovoltaic technology for satellite power sources that could provide up to an order of magnitude saving in both weight and cost, and is inherently radiation-tolerant through use of thin film technology and thin foil substrates such as 5-mil thick stainless steel foil or 1-mil thick Ti. Current single crystal technology for space power can cost more than $300 per watt at the array level and weigh more than 1 kg/sq m equivalent to specific power of approx. 65 W/kg. Thin film material such as CuIn(1-x),Ga(x)S2, (CIGS2), CuIn(1-x), G(x)Se(2-y),S(y), (CIGSS) or amorphous hydrogenated silicon (a-Si:H) may be able to reduce both the cost and mass per unit area by an order of magnitude. Manufacturing costs for solar arrays are an important consideration for total spacecraft budget. For a medium sized 5kW satellite, for example, the array manufacturing cost alone may exceed $2 million. Moving to thin film technology could reduce this expense to less than $500 K. Previous work at FSEC demonstrated the potential of achieving higher efficiencies from CIGSS thin film solar cells on 5-mil thick stainless steel foil as well as initial stages of facility augmentation for depositing thin film solar cells on larger (6"x 4") substrates. This paper presents further progress in processing on metal foil substrates. Also, previous work at DayStar demonstrated the feasibility of flexible-thin-film copper-indium-gallium-diselenide (CIGS) solar cells with a power-to-weight ratio in excess of 1000 W/kg. We will comment on progress on the critical issue of scale-up of the solar cell absorber deposition process. Several important technical issues need to be resolved

  6. Self-heating technique of metallic substrate for reel-to-reel and double-sided deposition of YBa{sub 2}Cu{sub 3}O{sub 7-δ} films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei; Zhao, Ruipeng; Xue, Yan; He, Yuanying; Zhang, Pan; Tao, Bowan; Xiong, Jie; Li, Yanrong [University of Electronic Science and Technology of China, State Key Laboratory of Electronic Thin Film and Integrated Devices, Chengdu (China); Wang, Hui [Chinese Academy of Sciences, Applied Research Laboratory of Superconduction and New Material, Institute of Electrical Engineering, Beijing (China)

    2016-02-15

    A new, simple, and highly efficient heating technology for metal tape substrates is proposed and applied to reel-to-reel and double-sided film deposition. In this technology, direct electrical current (I{sub DC}) is conducted into the metal layer of oxide-buffered metal substrate to induce heat. Different substrate surface temperatures were achieved by varying I{sub DC} from 22 to 25 A. At these temperatures, a series of 1-μm-thick and 5-cm-long YBa{sub 2}Cu{sub 3}O{sub 7-δ} (YBCO) films were fabricated on ion-beam-assisted deposition (IBAD) templates through metal organic chemical vapor deposition. X-ray diffraction analysis on the samples revealed that the YBCO film changed its growth mode from mixed a-axis and c-axis to purely c-axis with increasing I{sub DC}. The optimal out-of-plane and in-plane texture reached ∝1.4 and 3.5 , respectively. A 30-m-long and 500-nm-thick single-sided YBCO-coated conductor was also prepared through reel-to-reel deposition using the proposed heating method. The fabricated conductor presented homogeneous crystallization and texture and exhibited a critical current density at self-field and 77 K (J{sub c} {sub 77K,} {sub 0T}) of 2.8-3.2 MA/cm{sup 2}. Moreover, 500-nm-thick YBCO films were fabricated simultaneously on both sides of the double-sided IBAD template. The two sides of films demonstrated uniform texture and J{sub c} {sub 77K,} {sub 0T} of 3.2 MA/cm{sup 2}. Results demonstrated that the proposed substrate heating technology can be used for reel-to-reel and double-sided deposition of YBCO-coated conductors. (orig.)

  7. The effect of substrate orientation on the kinetics and thermodynamics of initial oxide-film growth on metals

    Energy Technology Data Exchange (ETDEWEB)

    Reichel, Friederike

    2007-11-19

    This thesis addresses the effect of the parent metal-substrate orientation on the thermodynamics and kinetics of ultra-thin oxide-film growth on bare metals upon their exposure to oxygen gas at low temperatures (up to 650 K). A model description has been developed to predict the thermodynamically stable microstructure of a thin oxide film grown on its bare metal substrate as function of the oxidation conditions and the substrate orientation. For Mg and Ni, the critical oxide-film thickness is less than 1 oxide monolayer and therefore the initial development of an amorphous oxide phase on these metal substrates is unlikely. Finally, for Cu and densely packed Cr and Fe metal surfaces, oxide overgrowth is predicted to proceed by the direct formation and growth of a crystalline oxide phase. Further, polished Al single-crystals with {l_brace}111{r_brace}, {l_brace}100{r_brace} and {l_brace}110{r_brace} surface orientations were introduced in an ultra-high vacuum system for specimen processing and analysis. After surface cleaning and annealing, the bare Al substrates have been oxidized by exposure to pure oxygen gas. During the oxidation, the oxide-film growth kinetics has been established by real-time in-situ spectroscopic ellipsometry. After the oxidation, the oxide-film microstructures were investigated by angle-resolved X-ray photoelectron spectroscopy and low energy electron diffraction. Finally, high-resolution transmission electron microscopic analysis was applied to study the microstructure and morphology of the grown oxide films on an atomic scale. (orig.)

  8. Jet formation in spallation of metal film from substrate under action of femtosecond laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Inogamov, N. A., E-mail: nailinogamov@googlemail.com [Russian Academy of Sciences, Landau Institute for Theoretical Physics (Russian Federation); Zhakhovskii, V. V. [Dukhov All-Russia Research Institute of Automatics (Russian Federation); Khokhlov, V. A. [Russian Academy of Sciences, Landau Institute for Theoretical Physics (Russian Federation)

    2015-01-15

    It is well known that during ablation by an ultrashort laser pulse, the main contribution to ablation of the substance is determined not by evaporation, but by the thermomechanical spallation of the substance. For identical metals and pulse parameters, the type of spallation is determined by film thickness d{sub f}. An important gauge is metal heating depth d{sub T} at the two-temperature stage, at which electron temperature is higher than ion temperature. We compare cases with d{sub f} < d{sub T} (thin film) and d{sub f} ≫ d{sub T} (bulk target). Radius R{sub L} of the spot of heating by an optical laser is the next (after d{sub f}) important geometrical parameter. The morphology of film bulging in cases where d{sub f} < d{sub T} on the substrate (blistering) changes upon a change in radius R{sub L} in the range from diffraction limit R{sub L} ∼ λ to high values of R{sub L} ≫ λ, where λ ∼ 1 μm is the wavelength of optical laser radiation. When d{sub f} < d{sub T}, R{sub L} ∼ λ, and F{sub abs} > F{sub m}, gold film deposited on the glass target acquires a cupola-shaped blister with a miniature frozen nanojet in the form of a tip on the circular top of the cupola (F{sub abs} and F{sub m} are the absorbed energy and the melting threshold of the film per unit surface area of the film). A new physical mechanism leading to the formation of the nanojet is proposed.

  9. Oxidative damage to collagen and related substrates by metal ion/hydrogen peroxide systems

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    1997-01-01

    (II)-H2O2 instead of Fe(II)-H2O2, evidence has been obtained for: i) altered sites of attack and fragmentation, ii) C-terminal decarboxylation, and iii) hydrogen abstraction at N-terminal alpha-carbon sites. This altered behaviour is believed to be due to the binding of copper ions to some substrates and...... (.CHR'R"), and alpha-carbon[.C(R)(NH-)CO-,R = side-chain]radicals. Reaction with collagen gave both broad anisotropic signals, from high-molecular-weight protein-derived radicals, and isotropic signals from mobile species. The latter may be low-molecular-weight fragments, or mobile side-chain species......; these signals are similar to those from the alpha-carbon site of peptides and the side-chain of lysine. Enzymatic digestion of the large, protein-derived, species releases similar low-molecular-weight adducts. The metal ion employed has a dramatic effect on the species observed. With Cu(I)-H2O2 or Cu...

  10. Modeling of metal nanocluster growth on patterned substrates and surface pattern formation under ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, Satoshi

    2012-11-01

    This work addresses the metal nanocluster growth process on prepatterned substrates, the development of atomistic simulation method with respect to an acceleration of the atomistic transition states, and the continuum model of the ion-beam inducing semiconductor surface pattern formation mechanism. Experimentally, highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO{sub 2} surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well-separated. The first topic is the investigation of this growth process with a continuum theoretical approach to the surface gas condensation as well as an atomistic cluster growth model. The atomistic simulation model is a lattice-based kinetic Monte-Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag monomers and {approx}1 nm square surface migration ranges of Ag monomers. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns. The second topic specifies the acceleration scheme utilized in the metallic cluster growth model. Concerning the atomistic movements, a classical harmonic transition state theory is considered and applied in discrete lattice cells with hierarchical transition levels. The model results in an effective reduction of KMC simulation steps by utilizing a classification scheme of transition levels for thermally activated atomistic diffusion processes. Thermally activated atomistic movements

  11. Investigating the molecule-substrate interaction of prototypic tetrapyrrole compounds: Adsorption and self-metalation of porphine on Cu(111)

    International Nuclear Information System (INIS)

    We report on the adsorption and self-metalation of a prototypic tetrapyrrole compound, the free-base porphine (2H-P), on the Cu(111) surface. Our multitechnique study combines scanning tunneling microscopy (STM) results with near-edge X-ray absorption fine-structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) data whose interpretation is supported by density functional theory calculations. In the first layer in contact with the copper substrate the molecules adsorb coplanar with the surface as shown by angle-resolved NEXAFS measurements. The quenching of the first resonance in the magic angle spectra of both carbon and nitrogen regions indicates a substantial electron transfer from the substrate to the LUMO of the molecule. The stepwise annealing of a bilayer of 2H-P molecules sequentially transforms the XP and NEXAFS signatures of the nitrogen regions into those indicative of the coordinated nitrogen species of the metalated copper porphine (Cu-P), i.e., we observe a temperature-induced self-metalation of the system. Pre- and post-metalation species are clearly discriminable by STM, corroborating the spectroscopic results. Similar to the free-base porphine, the Cu-P adsorbs flat in the first layer without distortion of the macrocycle. Additionally, the electron transfer from the copper surface to the molecule is preserved upon metalation. This behavior contrasts the self-metalation of tetraphenylporphyrin (2H-TPP) on Cu(111), where both the molecular conformation and the interaction with the substrate are strongly affected by the metalation process.

  12. Investigating the molecule-substrate interaction of prototypic tetrapyrrole compounds: Adsorption and self-metalation of porphine on Cu(111)

    Energy Technology Data Exchange (ETDEWEB)

    Diller, K.; Klappenberger, F.; Allegretti, F.; Papageorgiou, A. C.; Fischer, S.; Wiengarten, A.; Joshi, S.; Seufert, K.; Ecija, D.; Auwaerter, W.; Barth, J. V. [Physik Department E20, Technische Universitaet Muenchen, James-Franck-Str. 1, D-85748 Garching (Germany)

    2013-04-21

    We report on the adsorption and self-metalation of a prototypic tetrapyrrole compound, the free-base porphine (2H-P), on the Cu(111) surface. Our multitechnique study combines scanning tunneling microscopy (STM) results with near-edge X-ray absorption fine-structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) data whose interpretation is supported by density functional theory calculations. In the first layer in contact with the copper substrate the molecules adsorb coplanar with the surface as shown by angle-resolved NEXAFS measurements. The quenching of the first resonance in the magic angle spectra of both carbon and nitrogen regions indicates a substantial electron transfer from the substrate to the LUMO of the molecule. The stepwise annealing of a bilayer of 2H-P molecules sequentially transforms the XP and NEXAFS signatures of the nitrogen regions into those indicative of the coordinated nitrogen species of the metalated copper porphine (Cu-P), i.e., we observe a temperature-induced self-metalation of the system. Pre- and post-metalation species are clearly discriminable by STM, corroborating the spectroscopic results. Similar to the free-base porphine, the Cu-P adsorbs flat in the first layer without distortion of the macrocycle. Additionally, the electron transfer from the copper surface to the molecule is preserved upon metalation. This behavior contrasts the self-metalation of tetraphenylporphyrin (2H-TPP) on Cu(111), where both the molecular conformation and the interaction with the substrate are strongly affected by the metalation process.

  13. Mechanical behaviour of metallic thin films on polymeric substrates and the effect of ion beam assistance on crack propagation

    International Nuclear Information System (INIS)

    The mechanisms of crack propagation in metallic films on polymeric substrates have been studied through in situ atomic force microscopy observations of thin films under tensile stresses and finite element stress calculations. Two series of films - ones deposited with ion beam assistance, the others without - have been investigated. The observations and stress calculations show that ion beam assistance can change drastically the propagation of cracks in coated materials: by improving the adhesion film/substrate, it slows down the delamination process, but in the same time enhances the cracks growth in the thickness of the material

  14. Structural study of ZnSe films grown on substrate with In{sub x}Ga{sub 1-x}As and Al{sub 1-x}Ga{sub x}As buffer layers: strain, relaxation and lattice parameter

    Energy Technology Data Exchange (ETDEWEB)

    Perez Ladron de Guevara, H.; Gaona-Couto, A.; Vidal, M.A. [Instituto de Investigacion En Comunicacion Optica (IICO), Universidad Autonoma de San Luis Potosi, San Luis Potosi (Mexico)]. E-mail: mavidal@cactus.iico.uaslp.mx; Luyo Alvarado, J.; Melendez Lira, M.; Lopez-Lopez, M. [Departamento de Fisica, Centro de Investigacion y Estudios Avanzados del IPN, Mexico DF (Mexico)

    2002-06-21

    ZnSe layers of various thickness were grown on (001) GaAs substrates, using In{sub x}Ga{sub 1-x}As or Al{sub 1-x}Ga{sub x}As as buffer layers by molecular beam epitaxy and were studied by high-resolution x-ray diffraction. The principal structural characteristics of ZnSe layer and buffer layer were determined using several reflections, such as (004) and two pairs of coupled asymmetric reflections, namely (224), (-2-24) and (115) (-1-15). In order to evaluate their validity, the experimental data obtained from these reflections were handled by means of two known expressions found in the literature. We have found the relaxation process of ZnSe layers is well described by a geometrical model including the thermal strain and small strain due to work hardening. The relaxation process is faster for ZnSe grown on ternary buffer layers despite the fact that, some buffer layers are pseudomorphically grown to the substrate; therefore we conclude that not only the lattice mismatches have effect on the relaxation process but also the surface state of the buffer layer has an influence in this process. (author)

  15. Development and characterization of a metallic substrat for nanostructured membranes in the separation of gas mixtures; Entwicklung und Charakterisierung eines metallischen Substrats fuer nanostrukturierte Gastrennmembranen

    Energy Technology Data Exchange (ETDEWEB)

    Brands, Katharina

    2010-07-01

    In order to minimize the further increase of CO{sub 2}-content in the atmosphere, efforts are made to separate and store CO{sub 2} from exhaust gases of fossil power plants. Beside well-established separation techniques like chemical scrubber, the application of membrane technology is intensively investigated. One focus of this thesis is the development of metal supported substrates for microporous ceramic gas separation membranes, which are expected to have a higher mechanical stability than ceramic supported substrates. Starting with commercial porous steel substrates, interlayers are applied by wet powder spraying. For the interlayers the materials 1.4404-stainless steel and TiO{sub 2} or 1.4845-stainless steel and yttria stabilized zirconia (8YSZ) are chosen. The interlayers have to be defect-free, as minimal defects can deteriorate the membrane performance. By a subsequent mechanical treatment and an adjustment of the viscosity of the 8YSZ-suspension, the surface quality is considerably increased. At the same time the limits of the wet powder spraying process become obvious, as sporadic agglomerates, which are formed during the spraying process, cannot be totally avoided. The metal supported substrates are characterized regarding to the interaction between steel and ceramic, the roughness of the layers compared to polished ceramic substrates, the mechanical properties and the flow through the substrates. Furthermore microporous ceramic gas separation membranes are deposited on wet powder sprayed and dip coated substrates. The selectivity of these membranes is above Knudsen selectivity. The other focus of the thesis is the exposure of substrates and membranes to real flue gas conditions. Beside microporous ceramic membranes polymer membranes are analysed as a reference, which show a higher state of development compared to microporous ceramic membranes. For this purpose a test bed is built up in the EnBW ''Rheinhafendampfkraftwerk RDK 7&apos

  16. Determination of physical properties for β-TCP + chitosan biomaterial obtained on metallic 316L substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mina, A. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Tecno-Academia ASTIN SENA Reginal Valle (Colombia); Castaño, A. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Caicedo, J.C., E-mail: julio.cesar.caicedo@correo.univalle.edu.co [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Caicedo, H.H. [Biologics Research, Biotechnology Center of Excellence, Janssen R& D, LLC, Pharmaceutical Companies of Johnson & Johnson, Spring House, PA 19477 (United States); National Biotechnology & Pharmaceutical Association, Chicago, IL 60606 (United States); Aguilar, Y. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia)

    2015-06-15

    Material surface modification, particularly the deposition of special coatings on the surface of surgical implants, is extensively used in bone tissue engineering applications. β-Tricalcium phosphate/Chitosan (β-TCP/Ch) coatings were deposited on 316L stainless steel (316L SS) substrates by a cathodic electro-deposition technique at different coating compositions. The crystal lattice arrangements were analyzed by X-Ray diffraction (XRD), and the results indicated that the crystallographic structure of β-TCP was affected by the inclusion of the chitosan content. The changes in the surface morphology as a function of increasing chitosan in the coatings via scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that root-mean square values of the β-TCP/Ch coatings decreased by further increasing chitosan percentage. The elastic–plastic characteristics of the coatings were determined by conducting nanoindentation test, indicating that increase of chitosan percentage is directly related to increase of hardness and elastic modulus of the β-TCP/Ch coatings. Tribological characterization was performed by scratch test and pin-on-disk test to analyze the changes in the surface wear of β-TCP/Ch coatings. Finally, the results indicated an improvement in the mechanical and tribological properties of the β-TCP/Ch coatings as a function of increasing of the chitosan percentage. This new class of coatings, comprising the bioactive components, is expected not only to enhance the bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. - Highlights: • Superficial phenomenon that occurs in tribological surface of β-tricalcium phosphate-chitosan coatings. • Improvement on surface mechanical properties of ceramic-polymeric and response to surface tribological damage. • β-tricalcium phosphate-chitosan coatings that offer highest performance in the biomedical devices.

  17. Diameter distribution of thermally evaporated indium metal islands on silicon substrates

    Science.gov (United States)

    Balch, Joleyn; Tsakalakos, Loucas; Huber, William; Grande, James; Knussman, Michael; Cale, Timothy S.

    2007-09-01

    Although many groups have studied the initial growth stages of various metals, including indium, there is little information in literature on diameter distributions of indium in relation to film thickness or annealing conditions. This paper reports island size distributions of thermally evaporated In islands on Si (100) and Si (111) substrates for nominal film thicknesses ranging from 5 to 50 nm. Because indium has a low melting temperature, and therefore a high homologous temperature at room temperature, 3-dimensional islands form during deposition with no subsequent heat treatments needed. Island diameters were calculated using commercial image analysis software in conjunction with SEM images of the samples. It is found that there is a bimodal island diameter distribution for nominal indium thicknesses greater than 5 nm. While the diameters of the larger islands increase exponentially with nominal thickness, those of the smaller islands increase linearly, and therefore more slowly, with nominal thickness. For nominal thickness of 50 nm, the average diameters of the small and large islands differ by almost an order of magnitude. Anneal conditions were studied in an attempt to narrow diameter distributions. Samples of each nominal thickness were annealed at temperatures ranging from 360°C to 550°C and the diameters again measured. The range of island diameters become narrower with 360°C anneal and volume average island diameter increases by ~30-50%. This narrowing of the distribution occurs due to smaller islands being absorbed by the larger in a process akin to Ostwald ripening, which is facilitated by higher surface diffusivities at higher homologous temperatures.

  18. Determination of physical properties for β-TCP + chitosan biomaterial obtained on metallic 316L substrates

    International Nuclear Information System (INIS)

    Material surface modification, particularly the deposition of special coatings on the surface of surgical implants, is extensively used in bone tissue engineering applications. β-Tricalcium phosphate/Chitosan (β-TCP/Ch) coatings were deposited on 316L stainless steel (316L SS) substrates by a cathodic electro-deposition technique at different coating compositions. The crystal lattice arrangements were analyzed by X-Ray diffraction (XRD), and the results indicated that the crystallographic structure of β-TCP was affected by the inclusion of the chitosan content. The changes in the surface morphology as a function of increasing chitosan in the coatings via scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that root-mean square values of the β-TCP/Ch coatings decreased by further increasing chitosan percentage. The elastic–plastic characteristics of the coatings were determined by conducting nanoindentation test, indicating that increase of chitosan percentage is directly related to increase of hardness and elastic modulus of the β-TCP/Ch coatings. Tribological characterization was performed by scratch test and pin-on-disk test to analyze the changes in the surface wear of β-TCP/Ch coatings. Finally, the results indicated an improvement in the mechanical and tribological properties of the β-TCP/Ch coatings as a function of increasing of the chitosan percentage. This new class of coatings, comprising the bioactive components, is expected not only to enhance the bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. - Highlights: • Superficial phenomenon that occurs in tribological surface of β-tricalcium phosphate-chitosan coatings. • Improvement on surface mechanical properties of ceramic-polymeric and response to surface tribological damage. • β-tricalcium phosphate-chitosan coatings that offer highest performance in the biomedical devices

  19. Chemically-modified graphene sheets as an active layer for eco-friendly metal electroplating on plastic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Joon-Suk; Hwang, Taeseon; Nam, Gi-Yong; Hong, Jung-Pyo [Department of Polymer Science and Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-gu, Suwon, 440-746 (Korea, Republic of); Bae, Ah-Hyun; Son, Sang-Ik; Lee, Geun-Ho; Sung, Hak kyung [Manufacturing Tech. Center, Samsung Electronics Co., Ltd., Maetan-dong, Yeongtong-gu, Suwon, 443-742 (Korea, Republic of); Choi, Hyouk Ryeol; Koo, Ja Choon [School of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Nam, Jae-Do, E-mail: jdnam@skku.edu [Department of Polymer Science and Engineering, Sungkyunkwan University, Chunchun-dong, Jangan-gu, Suwon, 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon (Korea, Republic of)

    2012-10-30

    Eco-friendly nickel (Ni) electroplating was carried out on a plastic substrate using chemically modified graphene sheets as an active and conductive layer to initiate electroplating without using conventional pre-treatment or electroless metal-seeding processes. A graphene oxide (GO) solution was self-assembled on a polyethylene terephthalate (PET) film followed by evaporation to give GO layers (thickness around 6.5 {mu}m) on PET (GO/PET) film. Then, the GO/PET film was chemically and thermally reduced to convert the GO layers to reduced graphene oxide (RGO) layers on the PET substrate. The RGO-coated PET (RGO/PET) film showed the sheet resistance of 100 {Omega} per square. On RGO/PET film, Ni electroplating was conducted under the constant-current condition and the entire surface of the PET film was completely metalized with Ni without any voids.

  20. Chemically-modified graphene sheets as an active layer for eco-friendly metal electroplating on plastic substrates

    International Nuclear Information System (INIS)

    Eco-friendly nickel (Ni) electroplating was carried out on a plastic substrate using chemically modified graphene sheets as an active and conductive layer to initiate electroplating without using conventional pre-treatment or electroless metal-seeding processes. A graphene oxide (GO) solution was self-assembled on a polyethylene terephthalate (PET) film followed by evaporation to give GO layers (thickness around 6.5 μm) on PET (GO/PET) film. Then, the GO/PET film was chemically and thermally reduced to convert the GO layers to reduced graphene oxide (RGO) layers on the PET substrate. The RGO-coated PET (RGO/PET) film showed the sheet resistance of 100 Ω per square. On RGO/PET film, Ni electroplating was conducted under the constant-current condition and the entire surface of the PET film was completely metalized with Ni without any voids.

  1. Direct growth of Keggin polyoxometalates incorporated copper 1,3,5-benzenetricarboxylate metal organic framework films on a copper metal substrate

    International Nuclear Information System (INIS)

    Keggin heteropolyacid incorporated Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylic acid) thin films were grown on metallic Cu substrates in various solvents at ambient conditions. The Keggin heteropolyacid templated the growth of Cu3(BTC)2 crystals while the Cu substrate served as Cu2+-ion source. To obtain smooth, homogeneous films the optimal growth conditions found were in an ethanolic solution in contact with ambient air. X-ray diffraction measurements showed a preferred (100) orientation of the Cu3(BTC)2 crystals in ethanol while the use of a water-based solvent yielded a dominating (111) orientation. - Research Highlights: → Direct MOF formation without salt as metal-ion source. → Tunable growth speed by supplying oxidizing agents. → Tunable crystal orientation by choice of solvent.

  2. Epitaxial growth of bcc transition metal films and superlattices onto MgO (111), (011) and (001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mattson, J.E.; Fullerton, E.E.; Sowers, C.H.; Bader, S.D.

    1994-04-01

    We demonstrate epitaxial growth of the bcc transition metals Nb, Mo, Fe, and Cr via sputtering onto single crystal MgO substrates. The epitaxial growth orientations are (011), (112) and (001) when grown onto MgO (111), (011) and (001), respectively. Further we demonstrate that under appropriate growth conditions, superlattices of these materials (e.g., Fe/Cr, Fe/V and Mo/V) can be grown with the same epitaxial order as the films.

  3. A facile metal-free "grafting-from" route from acrylamide-based substrate toward complex macromolecular combs

    KAUST Repository

    Zhao, Junpeng

    2013-01-01

    High-molecular-weight poly(N,N-dimethylacrylamide-co-acrylamide) was used as a model functional substrate to investigate phosphazene base (t-BuP 4)-promoted metal-free anionic graft polymerization utilizing primary amide moieties as initiating sites. The (co)polymerization of epoxides was proven to be effective, leading to macromolecular combs with side chains being single- or double-graft homopolymer, block copolymer and statistical copolymer. © 2013 The Royal Society of Chemistry.

  4. Atomized Spraying of Liquid Metal Droplets on Desired Substrate Surfaces as a Generalized Way for Ubiquitous Printed Electronics

    OpenAIRE

    Zhang, Qin; Gao, Yunxia; Liu, Jing

    2013-01-01

    A direct electronics printing technique through atomized spraying for patterning room temperature liquid metal droplets on desired substrate surfaces is proposed and experimentally demonstrated for the first time. This method has generalized purpose and is highly flexible and capable of fabricating electronic components on any desired target objects, with either flat or rough surfaces, made of different materials, or different orientations from 1-D to 3-D geometrical configurations. With a pr...

  5. Molecular dynamics simulation of fabrication of Cu mono-component metallic glass by physical vapor deposition on Zr substrate

    CERN Document Server

    Yu, Yang; Cui, Fenping

    2016-01-01

    In this work, the single-component Cu metallic glass was fabricated by the physical vapor deposition on the Zr (0001) crystal substrate at 100 K using the classical molecular dynamic simulation. The same deposition process was performed on the Cu (1 0 0) and Ni (1 0 0) crystal substrate for comparison, only the Cu crystal deposited layer with the fcc structure can be obtained. When depositing the Cu atoms on the Zr substrate at 300 K, the crystal structure was formed, which indicates that except the suitable substrate, low temperature is also a key factor for the amorphous structure formation. The Cu liquid quenching from 2000 K to 100 K were also simulated with the cooling rate 1012 K/s to form the Cu glass film in this work. The Cu metallic glass from the two different processes (physical vapor deposition and rapid thermal quenching from liquid) revealed the same radial distribution function and X-ray diffraction pattern, but the different microstructure from the coordination number and Voronoi tessellation...

  6. Adhesion of ceramic coating on thin and smooth metal substrate: A novel approach with a nano-structured ceramic interlayer

    International Nuclear Information System (INIS)

    The adhesion of plasma-sprayed coating is, to a large extent, controlled by the cleanness and roughness of the surface on which the coating is deposited. So, most of the plasma spray procedures involve surface pretreatment by grit-blasting to adapt the roughness of the surface to the size of the impacting particles. This preparation process brings about compressive stresses that make it inappropriate for thin substrates. The present works aim to elaborate a thick ceramic coating (about 0.5 mm thick) on a thin metal substrate (1 mm thick) with a smooth surface (Ra of about 0.4 μm). The coating system is intended for use in a Generation-IV nuclear energy system. It must exhibit a good adhesion between the ceramic topcoat and the smooth metal substrate to meet the specifications of the application. Our approach consisted of depositing the ceramic topcoat by air plasma spraying on a few micrometers thick ceramic layer made by suspension plasma spraying. This nano-structured layer played the role of a bond coat for the topcoat and made it possible to deposit it on the as-received substrate. The adhesion of the nano-structured layer was measured by the Vickers indentation cracking technique and that of the ceramic duplex coating system by tensile test. (authors)

  7. Microstructural analysis of InGaN/GaN epitaxial layers of metal organic chemical vapor deposition on c-plane of convex patterned sapphire substrate

    International Nuclear Information System (INIS)

    The microstructures of the P-GaN (250 nm)/GaN cap (∼ 35 nm)/7 pairs of InGaN/GaN MQWs (multi-quantum wells)/n-GaN (3 μm)/HT (high temperature)-GaN (3 μm)/LT (low temperature)-GaN buffer (5 nm) on c-plane convex patterned sapphire substrate were analyzed using transmission electron microscopy (TEM). High density of dislocations in the LT-GaN buffer layer at both flat and convex patterned regions was observed to form. At the flat region, some of high dislocations formed at LT-GaN buffer grew over, bended to from stair-like dislocations extended along the edge of the convex pattern and then transformed to TDs (threading dislocations) extending through the InGaN/GaN epitaxial layers. However, few TDs reached the top of the epitaxial layers. Quantitative analysis revealed that the dislocation density has been drastically reduced to ∼ 106 cm−2, reducing formation of V-defects at the 7 pairs of multi-quantum-wells near the surface. - Highlights: • The InGaN/GaN epitaxial layers were grown on convex patterned sapphire substrate. • We systematically study the defect structures by transmission electron microscopy. • Reduce threading dislocation and V defect by growth on convex pattered substrate. • Improving of overall microstructure by growth on convex pattern substrate

  8. Probing the structural dependency of photoinduced properties of colloidal quantum dots using metal-oxide photo-active substrates

    Energy Technology Data Exchange (ETDEWEB)

    Patty, Kira; Campbell, Quinn; Hamilton, Nathan; West, Robert G. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Sadeghi, Seyed M., E-mail: seyed.sadeghi@uah.edu [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Nano and Micro Device Center, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Mao, Chuanbin [Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma 73019 (United States)

    2014-09-21

    We used photoactive substrates consisting of about 1 nm coating of a metal oxide on glass substrates to investigate the impact of the structures of colloidal quantum dots on their photophysical and photochemical properties. We showed during irradiation these substrates can interact uniquely with such quantum dots, inducing distinct forms of photo-induced processes when they have different cores, shells, or ligands. In particular, our results showed that for certain types of core-shell quantum dot structures an ultrathin layer of a metal oxide can reduce suppression of quantum efficiency of the quantum dots happening when they undergo extensive photo-oxidation. This suggests the possibility of shrinking the sizes of quantum dots without significant enhancement of their non-radiative decay rates. We show that such quantum dots are not influenced significantly by Coulomb blockade or photoionization, while those without a shell can undergo a large amount of photo-induced fluorescence enhancement via such blockade when they are in touch with the metal oxide.

  9. The influence of metal substrates and porcelains on the shade of metal-ceramic complex: A spectrophotometric study

    OpenAIRE

    Kavitha Janardanan; Sreelal Thankappan Pillai; Harshakumar Karunakaran

    2012-01-01

    Background: The final esthetic outcome of a metal-ceramic restoration is influenced by several factors including the type of the underlying metal as well as the brand of the ceramic. Settings and Design: An in vitro study. Aims: The purpose of the in vitro study was to investigate the influence of four types of metal-ceramic alloys and two porcelain systems on the color co-ordinates of the metal-ceramic complex. It also aimed at establishing a color index which correlated the color of t...

  10. Do CVD grown graphene films have antibacterial activity on metallic substrates?

    CERN Document Server

    Dellieu, Louis; Reckinger, Nicolas; Didembourg, Christian; Letesson, Jean-Jacques; Sarrazin, Michael; Deparis, Olivier; Matroule, Jean-Yves; Colomer, Jean-François

    2014-01-01

    Accurate assessment of the antibacterial activity of graphene requires consideration of both the graphene fabrication method and, for supported films, the properties of the substrate. Large-area graphene films produced by chemical vapor deposition were grown directly on copper substrates or transferred on a gold substrate and their effect on the viability and proliferation of the Gram-positive bacteria Staphylococcus aureus and the Gram-negative bacteria Escherichia coli were assessed. The viability and the proliferation of both bacterial species were not affected when they were grown on a graphene film entirely covering the gold substrate, indicating that conductivity plays no role on bacterial viability and graphene has no antibacterial activity against S. aureus and E. coli. On the other hand, antibacterial activity was observed when graphene coated the copper substrates, resulting from the release of bactericidal cupric ions in inverse proportion to the graphene surface coverage.

  11. Determination of the thickness of two-dimensional transition-metal dichalcogenide by the Raman intensity of the substrate

    Science.gov (United States)

    Wang, Ying Ying; Zhi Li, Ai; Hao Wang, Yi; Liang, Yao; Jiang, Jie; Nan, Hai Yan; Ni, Zhen Hua; Wang, Dong; Zhong, Bo; Wen, Guang Wu

    2016-02-01

    Two-dimensional (2D) transition-metal dichalcogenide (TMD) exhibits thickness-dependent optical, electronic, mechanical, chemical and vibrational properties, and a fast, non-destructive thickness characterization technique is very important for fully understanding the thickness-dependent properties of TMD nanosheets. MoS2 and WSe2 nanosheets with different layer numbers are fabricated by a mechanical exfoliation method and transferred onto SiO2 (300 nm)/Si substrate. In this work, it is found that the Raman area (i.e. the integrated intensity) ratio between the Si peak from SiO2/Si substrate underneath TMD nanosheets (ASi) and that from bare SiO2/Si substrate (ASi(0)), ASi/ASi(0), can be used to accurately identify the layer number of those TMD nanosheets. ASi/ASi(0) is then calculated using the Fresnel equations, the absorption of TMD nanosheets is included in the calculation, which has not been considered in previous work. The consideration of absorption is especially necessary for TMD which has a quite large extinction coefficient. Identification of single-layer TMD with different complex refractive indices on SiO2/Si substrate and on Si substrate using this method is given. The effects of thickness of SiO2 and excitation wavelength on the layer number identification using this method are also discussed.

  12. Buffer layer for thin film structures

    Energy Technology Data Exchange (ETDEWEB)

    Foltyn, Stephen R.; Jia, Quanxi; Arendt, Paul N.; Wang, Haiyan

    2010-06-15

    A composite structure including a base substrate and a layer of a mixture of strontium titanate and strontium ruthenate is provided. A superconducting article can include a composite structure including an outermost layer of magnesium oxide, a buffer layer of strontium titanate or a mixture of strontium titanate and strontium ruthenate and a top-layer of a superconducting material such as YBCO upon the buffer layer.

  13. Buffer layer for thin film structures

    Energy Technology Data Exchange (ETDEWEB)

    Foltyn, Stephen R.; Jia, Quanxi; Arendt, Paul N.; Wang, Haiyan

    2006-10-31

    A composite structure including a base substrate and a layer of a mixture of strontium titanate and strontium ruthenate is provided. A superconducting article can include a composite structure including an outermost layer of magnesium oxide, a buffer layer of strontium titanate or a mixture of strontium titanate and strontium ruthenate and a top-layer of a superconducting material such as YBCO upon the buffer layer.

  14. Crystal quality and electrical properties of p-type GaN thin film on Si(111 substrate by metal-organic chemical vapor deposition MOCVD

    Directory of Open Access Journals (Sweden)

    G.M. Wu

    2007-09-01

    Full Text Available Purpose: In this paper, p-GaN samples have been grown on silicon substrates under various processing conditions. The effects of growth tenperature and thermal annealing on the crystal quality and strain were carefully investigated. The electrical properties such as hole concentration and mobility would be discussed.Design/methodology/approach: GaN-based III–V semiconductors have become promising materials for short-wavelength optoelectronic devices because of their large and direct band gap energies. In this paper, p-GaN has been grown by metal-organic chemical vapor deposition (MOCVD at 900°C, 950°C, 1000°C, and 1050°C with low temperature LT-deposited AlN/AlGaN buffer layer.Findings: The mobility was achieved at 150 cm2/Vs and the hole concentration was 8x1017 cm-3. SIMS and XRD were used to measure and explain the relationships between hole concentration and the growth temperature. When the growth temperature was increased to 1000°C, the hole concentration was increased by ten times. According to the experimental results, the optimal growth temperature was 1000°C. After the thermal annealing process at temperature 850°C for 2 minutes, the FWHM of p-GaN was lowered to 617 arcsec. The effects of growth temperature were explained in the two temperature regions. From 900°C to 1000°C, the incorporation rate of Mg was slightly increased and the strain decreased with the growth temperature. Mg would provide holes and the lower strain would result in better crystal quality. The crystal quality and Mg concentration effects on hole concentration below 1000°C was thus beneficiary. On the other hand, when the growth temperature was further increased, the strain and FWHM increased while hole concentration decreased at 1050°C. At this high temperature, Si might become donor in GaN.Research limitations/implications: It was suggested that the hole concentration reduced at 1050°C due to the Si diffusion and the strain caused by Mg dopant

  15. New Failure Mode of Flip-Chip Solder Joints Related to the Metallization of an Organic Substrate

    Science.gov (United States)

    Jang, J. W.; Yoo, S. J.; Hwang, H. I.; Yuk, S. Y.; Kim, C. K.; Kim, S. J.; Han, J. S.; An, S. H.

    2015-10-01

    We report a new failure phenomenon during flip-chip die attach. After reflow, flip-chip bumps were separated between the Al and Ti layers on the Si die side. This was mainly observed at the Si die corner. Transmission electron microscopy images revealed corrosion of the Al layer at the edge of the solder bump metallization. The corrosion at the metallization edge exhibited a notch shape with high stress concentration factor. The organic substrate had Cu metallization with an organic solderable preservative (OSP) coating layer, where a small amount of Cl ions were detected. A solder bump separation mechanism is suggested based on the reaction between Al and Cl, related to the flow of soldering flux. During reflow, the flux will dissolve the Cl-containing OSP layer and flow up to the Al layer on the Si die side. Then, the Cl-dissolved flux will actively react with Al, forming AlCl3. During cooling, solder bumps at the Si die corner will separate through the location of Al corrosion. This demonstrated that the chemistry of the substrate metallization can affect the thermomechanical reliability of flip-chip solder joints.

  16. Fabrication of single-phase ε-GaSe films on Si(100) substrate by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Single-phase ε-gallium selenide (GaSe) films were fabricated on Si(100) substrate by metal organic chemical vapor deposition using dual-source precursors: triethylgallium (TEG) and hydrogen selenide (H2Se) with the flow ratio of [H2Se]/[TEG] being maintained at 1.2. In particular, an arsine (AsH3) flow was introduced to the Si substrate before the film deposition to induce an arsenic (As)-passivation effect on the substrate. The crystalline structure of GaSe films prepared was analyzed using X-ray diffraction and the surface morphology of them was characterized by scanning electron microscopy. It was found that the film quality could be improved by the As-passivation effect. The optical properties of the films were studied by temperature dependent photoluminescence (PL) measurements. PL spectra obtained with different distributions and intensities favored for resolving the superior material quality of the films produced on the substrate with As-passivation compared to those produced on the substrate without As-passivation. The former was dominated by the excitonic emissions for the whole temperature range of 20–300 K examined, while the latter was initially dominated by the defect-related emission at 1.907 eV for a low-temperature range ≦ 80 K and then became dominated by the weak excitonic emission band instead. The ε modification of GaSe films prepared was further recognized by the Raman scattering measurements conducted at room temperature. - Highlights: • Gallium selenide (GaSe) layered structures are fabricated on Si(100) substrate. • Metal–organic chemical vapor deposition is used for film fabrication. • Arsenic-passivation effects of Si substrate on the GaSe film quality are analyzed. • Photoluminescence measurements of GaSe polycrystals are reported

  17. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, P., E-mail: pdutta2@central.uh.edu; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V. [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); Zheng, N.; Ahrenkiel, P. [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States); Martinez, J. [Materials Evaluation Laboratory, NASA Johnson Space Center, Houston, Texas 77085 (United States)

    2014-09-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10{sup 7 }cm{sup −2}. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm{sup 2}/V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  18. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Bajikar, Sateesh S.; DeCarlo, Francesco; Song, Joshua J.

    1998-05-22

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized from pyromellitic anhydride and oxydianiline (PMDA-ODA).

  19. On the use, characterization and performance of silane coupling agents between organic coatings and metallic or ceramic substrates

    International Nuclear Information System (INIS)

    Examples are given of the use of organofunctional silane coupling agents for promoting bonding between organic coatings and metallic or ceramic (i.e. oxide) substrates. The orientation of the silane molecules and the type of bonding with the metal oxide can be determined successfully by Time-of-Flight SIMS. Oriented films of aminosilanes are demonstrated to be unstable in air. A prerinse with an inorganic silicate is introduced as a suitable method for masking the ubiquitous carbonaceous contamination at the metal surface, thus promoting the proper orientation and covalent bonding. Some practical applications are described, such as the pretreatment of Galvalumesqbullet surfaces as a replacement of existing chromate treatments in coil coating applications. Electrochemical Impedance Spectroscopy (EIS) is shown to be a powerful tool for studying the performance of the silane treatment under a paint. copyright 1996 American Institute of Physics

  20. Supercritical CO2 assisted electroless plating on polypropylene substrate-effect of injection speed on adhesive force of metal to polymer

    Science.gov (United States)

    Ohshima, Masahiro; Tsubouchi, Kensuke; Ishihara, Shota; Hikima, Yuta; Tengsuwan, Siwach

    2016-03-01

    The aqueous plating solution cannot be diffused into a plain polypropylene (PP) substrate and consequently Ni-P metal layer cannot be formed by electroless plating on the PP substrate with a satisfied degree of adhesive force unless the hydrophilicity of the substrate surface was increased. A block copolymer PP-b-polyethylene oxide (PP-b-PEO) was used to increase the hydrophilicity of the surface and the adhesive force of the metal layer to the satisfactory level. Our previous study showed the morphology of PP-b-PEO domain near the surface of substrate strongly affected the adhesiveness of the metal layer to the substrate. The degrees of elongation and orientation of the PP-b-PEO domains in PP matrix were the key factors of determining the thickness of the metal-PP composite layer and the resulting adhesive strength. In this study, the effect of injection molding condition on the degrees of elongation and orientation was investigated: PP/PP-b-PEO blend substrates were prepared by injection molding at different injection speed. The higher injection speed increased the degrees of elongation and orientation of copolymer and formed multilayered structure of the copolymer domains. It could produce the electroless plating PP substrate with the higher adhesive strength of the Ni-P metal layer to the PP substrate.

  1. Influence of vicinal sapphire substrate on the properties of N-polar GaN films grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhiyu; Zhang, Jincheng, E-mail: jchzhang@xidian.edu.cn; Xu, Shengrui; Chen, Zhibin; Yang, Shuangyong; Tian, Kun; Hao, Yue [Key Lab of Wide Band-Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi' an, Shaanxi 710071 (China); Su, Xujun [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215123 (China); Shi, Xuefang [School of Advanced Materials and Nanotechnology, Xidian University, Xi' an, Shaanxi 710071 (China)

    2014-08-25

    The influence of vicinal sapphire substrates on the growth of N-polar GaN films by metal-organic chemical vapor deposition is investigated. Smooth GaN films without hexagonal surface feature are obtained on vicinal substrate. Transmission electron microscope results reveal that basal-plane stacking faults are formed in GaN on vicinal substrate, leading to a reduction in threading dislocation density. Furthermore, it has been found that there is a weaker yellow luminescence in GaN on vicinal substrate than that on (0001) substrate, which might be explained by the different trends of the carbon impurity incorporation.

  2. Identification of novel in vivo MAP kinase substrates in Arabidopsis thaliana through use of tandem metal oxide affinity chromatography.

    Science.gov (United States)

    Hoehenwarter, Wolfgang; Thomas, Martin; Nukarinen, Ella; Egelhofer, Volker; Röhrig, Horst; Weckwerth, Wolfram; Conrath, Uwe; Beckers, Gerold J M

    2013-02-01

    Mitogen-activated protein kinase (MPK) cascades are important for eukaryotic signal transduction. They convert extracellular stimuli (e.g. some hormones, growth factors, cytokines, microbe- or damage-associated molecular patterns) into intracellular responses while at the same time amplifying the transmitting signal. By doing so, they ensure proper performance, and eventually survival, of a given organism, for example in times of stress. MPK cascades function via reversible phosphorylation of cascade components MEKKs, MEKs, and MPKs. In plants the identity of most MPK substrates remained elusive until now. Here, we provide a robust and powerful approach to identify and quantify, with high selectivity, site-specific phosphorylation of MPK substrate candidates in the model plant Arabidopsis thaliana. Our approach represents a two-step chromatography combining phosphoprotein enrichment using Al(OH)(3)-based metal oxide affinity chromatography, tryptic digest of enriched phosphoproteins, and TiO(2)-based metal oxide affinity chromatography to enrich phosphopeptides from complex protein samples. When applied to transgenic conditional gain-of-function Arabidopsis plants supporting in planta activation of MPKs, the approach allows direct measurement and quantification ex vivo of site-specific phosphorylation of several reported and many yet unknown putative MPK substrates in just a single experiment. PMID:23172892

  3. Performance characterization of metallic substrates coated by HVOF WC–Co

    International Nuclear Information System (INIS)

    Integral to the performance of high-velocity oxygen-fuel (HVOF) coatings is the thermo-mechanical interaction associated with the thermal misfit, or differences in thermal expansion coefficients (CTEs), between coating and substrate. This investigation reports results on the microstructures, chemical phase content, coating–substrate misfit residual stress, and wear resistance. For this purpose a systematic characterization of WC–Co sprayed coatings on a number of substrates covering a range of CTE values were pursued for both the as-coated and heat-treated conditions. The neutron diffraction technique in conjunction with sub-millimeter sized gauge volumes enabled depth-resolved studies of the stress in the coatings and substrates by paying special attention to the determination of the stress contribution attributed by the final spray process. In the as-coated condition the stress values in the coatings were compressive for CTEs larger than that of WC–Co and tensile for CTE lower than WC–Co. Wear resistance increased for increased compressive stress and macrohardness. In the heat-treated condition, this trend became enhanced due to increased compressive stress in the coatings. - Highlights: • Four different substrate systems coated with HVOF WC-Co has been investigated. • Each substrate set encompassed the grit-blast surface and as-coated conditions, as well as their heat-treated counterparts. • Microstructural, macrohardness, wear performance and depth-resolved residual stress characterised. • Successful application of neutron strain scanning to investigating the combined systems, coatings and substrates. • Link observed between macrohardness, residual stress and wear performance

  4. Performance characterization of metallic substrates coated by HVOF WC–Co

    Energy Technology Data Exchange (ETDEWEB)

    Venter, Andrew M., E-mail: andrew.venter@necsa.co.za [Research and Development Division, Necsa Limited, Pretoria (South Africa); School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa); Oladijo, O. Philip [School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa); Luzin, Vladimir [ANSTO (Australian Nuclear Science and Technology Organisation), Lucas Height (Australia); Cornish, Lesley A.; Sacks, Natasha [School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa)

    2013-12-31

    Integral to the performance of high-velocity oxygen-fuel (HVOF) coatings is the thermo-mechanical interaction associated with the thermal misfit, or differences in thermal expansion coefficients (CTEs), between coating and substrate. This investigation reports results on the microstructures, chemical phase content, coating–substrate misfit residual stress, and wear resistance. For this purpose a systematic characterization of WC–Co sprayed coatings on a number of substrates covering a range of CTE values were pursued for both the as-coated and heat-treated conditions. The neutron diffraction technique in conjunction with sub-millimeter sized gauge volumes enabled depth-resolved studies of the stress in the coatings and substrates by paying special attention to the determination of the stress contribution attributed by the final spray process. In the as-coated condition the stress values in the coatings were compressive for CTEs larger than that of WC–Co and tensile for CTE lower than WC–Co. Wear resistance increased for increased compressive stress and macrohardness. In the heat-treated condition, this trend became enhanced due to increased compressive stress in the coatings. - Highlights: • Four different substrate systems coated with HVOF WC-Co has been investigated. • Each substrate set encompassed the grit-blast surface and as-coated conditions, as well as their heat-treated counterparts. • Microstructural, macrohardness, wear performance and depth-resolved residual stress characterised. • Successful application of neutron strain scanning to investigating the combined systems, coatings and substrates. • Link observed between macrohardness, residual stress and wear performance.

  5. High-quality eutectic-metal-bonded AlGaAs-GaAs thin films on Si substrates

    Science.gov (United States)

    Venkatasubramanian, R.; Timmons, M. L.; Humphreys, T. P.; Keyes, B. M.; Ahrenkiel, R. K.

    1992-02-01

    Device quality GaAs-AlGaAs thin films have been obtained on Si substrates, using a novel approach called eutectic-metal-bonding (EMB). This involves the lattice-matched growth of GaAs-AlGaAs thin films on Ge substrates, followed by bonding onto a Si wafer. The Ge substrates are selectively removed by a CF4/O2 plasma etch, leaving high-quality GaAs-AlGaAs thin films on Si substrates. A minority-carrier lifetime of 103 ns has been obtained in a EMB GaAs-AlGaAs double heterostructure on Si, which is nearly forty times higher than the state-of-the-art lifetime for heteroepitaxial GaAs on Si, and represents the largest reported minority-carrier lifetime for a freestanding GaAs thin film. In addition, a negligible residual elastic strain in the EMB GaAs-AlGaAs films has been determined from Raman spectroscopy measurements.

  6. Evaluation of the barrier capability of Zr-Si films with different substrate temperature for Cu metallization

    International Nuclear Information System (INIS)

    Barrier capability of Zr-Si diffusion barriers in Cu metallization has been investigated. Amorphous Zr-Si diffusion barriers were deposited on the Si substrates by RF reactive magnetron sputtering under various substrate temperatures. An increase in substrate temperature results in a slightly decreased deposition rate together with an increase in mass density. An increase in substrate temperature also results in grain growth as deduced from field emission scanning electron microscopy (FE-SEM) micrographs. X-ray diffraction (XRD) spectra and Auger electron spectroscopy (AES) depth profiles for Cu/Zr-Si(RT)/Si and Cu/Zr-Si(300 deg. C)/Si samples subjected to anneal at various temperatures show that the thermal stability was strongly correlated with the deposition temperature (consequently different density and chemical composition etc.) of the Zr-Si barrier layers. ZrSi(300 deg. C) with higher mass density make the Cu/Zr-Si(300 deg. C)/Si sample more stable. The appearance of Cu3Si in the Cu/Zr-Si/Si sample is attributed to the failure mechanism which may be associated with the diffusion of Cu and Si via the grain boundaries of the Zr-Si barriers.

  7. Investigation of CeO2 Buffer Layer Effects on the Voltage Response of YBCO Transition Edge Bolometers

    DEFF Research Database (Denmark)

    Mohajeri, Roya; Nazifi, Rana; Wulff, Anders Christian;

    2016-01-01

    The effect on the thermal parameters of superconducting transition edge bolometers produced on a single crystalline SrTiO3 (STO) substrate with and without a CeO2 buffer layer was investigated. Metal organic deposition was used to deposit the 20 nm CeO2 buffer layer, while RF magnetron sputtering...... made by fitting the thermal parameters in the model with and without an additional CeO2 layer were found to be in agreement with the experimental observations....

  8. The role of substrate electrons in the wetting of a metal surface

    DEFF Research Database (Denmark)

    Schiros, T.; Takahashi, O.; Andersson, Klas Jerker;

    2010-01-01

    We address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution...

  9. Fabrication of a metal membrane on a perforated polymer substrate by palladium aerosol activation and subsequent electroless plating.

    Science.gov (United States)

    Byeon, Jeong Hoon; Hwang, Jungho

    2009-02-01

    Fabrication of a metal membrane on a perforated flexible poly(tetrafluoroethylene) (PTFE) substrate was developed by employing spark-generated palladium (Pd) aerosol activation and the subsequent electroless plating of Pd. After aerosol activation, Pd agglomerates of spark-generated primary particles (approximately 2.6 nm in diameter) with a face-centered-cubic structure were deposited uniformly on the PTFE substrate. Homogeneous Pd particles with an average size of 188 nm were tightly packed together to form a Pd membrane after Pd plating. The average plating rate of Pd during 30 min of plating at an activation intensity of 25 microg/cm(2) was 14.2 microg/cm(2) x min. PMID:20353212

  10. Metal capped polystyrene nanotubes arrays as super-hydrophobic substrates for SERS applications

    Science.gov (United States)

    Lovera, Pierre; Creedon, Niamh; Alatawi, Hanan; O'Riordan, Alan

    2014-05-01

    We present a low-cost and rapid fabrication and characterisations of polymer nanotubes based substrates inspired by a Gecko's foot, and demonstrate its suitability for Surface Enhanced Raman Scattering (SERS) applications. Substrates are fabricated in a simple, scalable and cost efficient way by melt wetting of polystyrene (PS) in an anodised alumina (AAO) template, followed by silver or gold evaporation. Scanning electron microscopy reveals the substrates are composed of a dense array of free-standing polystyrene nanotubes topped by silver nanocaps. The gaps (electromagnetic hot spots) between adjacent nanotubes are measured to be 30nm +/-15nm. SERS characterisation of the substrates, employing a monolayer of 4-aminothiophenol (4-ABT) as a model molecule, exhibits an enhancement factor of ~1.6 × 106. This value is consistent with the one obtained from 3D-Finite Difference Time Domain (3D-FDTD) simulations of a simplified version of the sample. The contact angle of the substrates is measured to be 150°, making them super-hydrophobic. This later property renders the samples compatible to very low sample volumes and highly sensitive detection (down to 408ppt) of the environmental pollutant crystal violet in water is demonstrated.

  11. Direct patterning of metallic micro/nano-structures on flexible polymer substrates by roller-based contact printing and infrared heating

    International Nuclear Information System (INIS)

    This paper presents a new micro/nano-fabrication method which can directly transfer a patterned metallic film from a silicon mold to a flexible polymer substrate. The basic idea is to coat a metallic thin layer on a silicon mold which has pre-defined surface features in micro- or nano-scale. Prior to the metallic film deposition, an anti-adhesion layer is first applied to the mold's surface so that the subsequently deposited metallic layer is only weakly attached to the mold. The silicon mold is then pressed by a roller against a polymer substrate while an infrared light source, such as an infrared lamp, is used to heat up the mold/substrate assembly. Energy of the infrared heating source is absorbed by the metal layer and subsequently heats up the polymer material in contact with the metal film through heat conduction. The temperature rising and the contact pressure at the metal/polymer interface create a stronger bonding interface which finally transfers the metallic patterns defined by the mold's surface features to the polymer substrate. Experiments have been carried out to demonstrate the feasibility and capabilities of the proposed method. Metallic structures with a smallest feature size of 60 nm and an imprinted area of 4 × 4 cm2 have been successfully patterned into PET films.

  12. Wood-Reinforced Polyphthalamide Resins: MultiFunctional Composite Coating for Metal Substrates

    Directory of Open Access Journals (Sweden)

    M. Barletta

    2014-01-01

    Full Text Available Protective layers were deposited on aluminum substrates by dipping them inside a fluidized bed (FB of wood and polyphthalamide powders. The experimental investigation looked into the influence of the main process parameters (number and composition of superimposed layers, heating temperature, and dipping time on the visual appearance, scratch adhesion, wear resistance, and thermal insulation of the resulting coatings. Micromechanical and tribological responses of the coatings were significantly improved by the effect of the wooden particles dispersed inside the polyphthalamide binder. An improvement of the thermal insulation was also achieved whatever the setting of the process parameters. Further, the coatings displayed good adhesion to the substrate and wear endurance.

  13. Localization of substrate-induced modification in the electronic structure of C-60 at fullerene-metal interfaces

    OpenAIRE

    Hunt, Michael R. C.; Rudolf, Petra; Modesti, Silvio

    1997-01-01

    Photoemission and electron-energy-loss-spectroscopy studies of C60 films deposited on Au(110) demonstrate that only the first layer of molecules, directly in contact with the metal substrate, display significant changes in electronic structure. If the Au(110) surface is precovered with Cs it is found that, at 298 K, the Cs can diffuse readily into a C60 thin film, preventing the formation of a localized interface. However, if a Cs precovered Au(110) sample is held at 98 K, subsequent depositi...

  14. Bias dependence of tunneling-electron-induced molecular fluorescence from porphyrin films on noble-metal substrates

    OpenAIRE

    Liu, H.W.; Le, Y.; Nishitani, Ryusuke; Aso, Y; Iwasaki, H.

    2007-01-01

    We investigated scanning tunneling microscope (STM)-excited luminescence from porphyrin (PhTPP and H2TPP) thin films on metal substrate (Au and Ag) under ambient conditions. Molecular fluorescence similar to the corresponding photoluminescence was observed from PhTPP/Au and H2TPP/Ag at both STM bias polarities. We found that at the same experimental condition and parameters, the STM-induced luminescence intensities of maxima peak are similar for PhTPP and H2TPP but weaker by a factor of about...

  15. State of the art and prospective of large scale applications of YBCO thick films grown on metallic substrates

    International Nuclear Information System (INIS)

    In the framework of the high temperature superconducting materials, YBa2Cu3O7 (YBCO) shows very interesting intrinsic superconducting transport properties at temperature higher than the liquid nitrogen temperature. These properties are very important in large scale applications: transport of energy, magnets, transformers, etc. Unfortunately the potential of this material cannot be achieved today, since it is very difficult to manufacture YBCO based tapes or cables. In the last years several groups have tried to overcome the problems with new fabrication techniques. In the present report the state of the art and the prospective in the field of YBCO film fabrication on metallic substrates are presented

  16. Protective conversion coating on mixed-metal substrates and methods thereof

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Matthew J.; Maddela, Surender

    2016-09-06

    Mixed-metal automotive vehicle bodies-in-white comprising ferrous metal surfaces, zinc surfaces, aluminum alloy surfaces, and magnesium alloy surfaces are cleaned and immersed in an aqueous bath comprising an adhesion promoter and an aqueous electrocoat bath (the adhesion promoter may be in the electrocoat bath. The adhesion promoter, which may be a cerium salt, is selected to react with each metal in the body surfaces to form an oxide layer that provides corrosion resistance for the surface and adherence for the deposited polymeric paint coating. The body is cathodic in the electrocoat deposition.

  17. The role of substrate electrons in the wetting of a metal surface

    OpenAIRE

    Schiros, T.; Takahashi, O; Andersson, Klas Jerker; Ostrom, H.; Pettersson, L. G. M.; Nilsson, A.; Ogasawara, H.

    2010-01-01

    We address how the electronic and geometric structures of metal surfaces determine water-metal bonding by affecting the balance between Pauli repulsion and electrostatic attraction. We show how the rigid d-electrons and the softer s-electrons utilize different mechanisms for the redistribution of charge that enables surface wetting. On open d-shell Pt(111), the ligand field of water alters the distribution of metal d-electrons to reduce the repulsion. The closed-shell Cu d(10) configuration o...

  18. Influence of various thickness metallic interlayers on opto-electric and mechanical properties of AZO thin films on PET substrates

    Science.gov (United States)

    Chang, R. C.; Li, T. C.; Lin, C. W.

    2012-02-01

    Various thickness metallic interlayers to improve the opto-electric and mechanical properties of aluminum-doped zinc oxide (AZO) thin films deposited on flexible polyethylene terephtalate (PET) substrates are studied. The effects of the interlayers on the resistance and transmittance of the AZO thin films are discussed. The result shows that the metallic interlayers effectively improve the electric resistance but reduce the optical transmittance of the AZO thin films. These phenomena become more obvious as the interlayer thickness increases. However, the AZO with an aluminum interlayer still behaves an acceptable transmittance. Moreover, mechanical tests indicate that the aluminum interlayer increases the hardness and modulus, and reduce the residual stress of the AZO thin films. In contrast, the silver and copper interlayers decrease the AZO's mechanical properties. Comparing to those without any interlayer, the results show that the best interlayer is the 6 nm thick aluminum film.

  19. On the possibility of contact-induced spin polarization in interfaces of armchair nanotubes with transition metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kuzubov, Alexander A. [Siberian Federal University, 79 Svobodny Prospect, 660041 Krasnoyarsk (Russian Federation); Kirensky Institute of Physics, 50 Akademgorodok, 660036 Krasnoyarsk (Russian Federation); Kovaleva, Evgenia A., E-mail: kovaleva.evgeniya1991@mail.ru [Siberian Federal University, 79 Svobodny Prospect, 660041 Krasnoyarsk (Russian Federation); Kirensky Institute of Physics, 50 Akademgorodok, 660036 Krasnoyarsk (Russian Federation); Tomilin, Felix N.; Mikhaleva, Natalya S.; Kuklin, Artem V. [Siberian Federal University, 79 Svobodny Prospect, 660041 Krasnoyarsk (Russian Federation); Kirensky Institute of Physics, 50 Akademgorodok, 660036 Krasnoyarsk (Russian Federation)

    2015-12-15

    The interaction between armchair carbon and boron nitride nanotubes (NT) with ferromagnetic transition metal (TM) surfaces, namely, Ni(111) and Co(0001), was studied by means of density functional theory. Different configurations of composite compartments mutual arrangement were considered. Partial densities of states and spin density spatial distribution of optimized structures were investigated. Influence of ferromagnetic substrate on nanotubes’ electronic properties was discussed. The values of spin polarization magnitude at the Fermi level are also presented and confirm the patterns of spin density spatial distribution. - Highlights: • Interaction of armchair nanotubes with ferromagnetic metal surfaces was investigated. • Different configurations of nanotube's location were considered. • For all nanotubes the energy difference between configurations is negligible. • Nanotubes were found to be more or less spin-polarized regarding to the configuration. • BN nanotubes demonstrate vanishing of the band gap and contact-induced conductivity.

  20. Influence of various thickness metallic interlayers on opto-electric and mechanical properties of AZO thin films on PET substrates

    International Nuclear Information System (INIS)

    Various thickness metallic interlayers to improve the opto-electric and mechanical properties of aluminum-doped zinc oxide (AZO) thin films deposited on flexible polyethylene terephtalate (PET) substrates are studied. The effects of the interlayers on the resistance and transmittance of the AZO thin films are discussed. The result shows that the metallic interlayers effectively improve the electric resistance but reduce the optical transmittance of the AZO thin films. These phenomena become more obvious as the interlayer thickness increases. However, the AZO with an aluminum interlayer still behaves an acceptable transmittance. Moreover, mechanical tests indicate that the aluminum interlayer increases the hardness and modulus, and reduce the residual stress of the AZO thin films. In contrast, the silver and copper interlayers decrease the AZO's mechanical properties. Comparing to those without any interlayer, the results show that the best interlayer is the 6 nm thick aluminum film.

  1. Metal-free magnetic conductor substrates for placement-immune antenna assemblies

    Science.gov (United States)

    Eubanks, Travis Wayne; Loui, Hung; McDonald, Jacob Jeremiah

    2015-09-29

    A magnetic conductor substrate produced for mounting to an antenna includes a sheet of dielectric lattice material having a length, a width and a thickness that is less than the length and less than the width. Within the sheet of dielectric lattice material is disposed an array of dielectric elements.

  2. Investigation of photocatalytic activity of titanium dioxide deposited on metallic substrates by DC magnetron sputtering

    DEFF Research Database (Denmark)

    Daviðsdóttir, Svava; Canulescu, Stela; Dirscherl, Kai;

    2013-01-01

    The photocatalytic properties of titanium dioxide (TiO2) coating in the anatase crystalline structure deposited on aluminium AA1050 alloy and stainless steel S316L substrates were investigated. The coating was prepared by DC magnetron sputtering. The microstructure and surface morphology of the...

  3. Bottom-up synthesis of ordered metal/oxide/metal nanodots on substrates for nanoscale resistive switching memory

    Science.gov (United States)

    Han, Un-Bin; Lee, Jang-Sik

    2016-05-01

    The bottom-up approach using self-assembled materials/processes is thought to be a promising solution for next-generation device fabrication, but it is often found to be not feasible for use in real device fabrication. Here, we report a feasible and versatile way to fabricate high-density, nanoscale memory devices by direct bottom-up filling of memory elements. An ordered array of metal/oxide/metal (copper/copper oxide/copper) nanodots was synthesized with a uniform size and thickness defined by self-organized nanotemplate mask by sequential electrochemical deposition (ECD) of each layer. The fabricated memory devices showed bipolar resistive switching behaviors confirmed by conductive atomic force microscopy. This study demonstrates that ECD with bottom-up growth has great potential to fabricate high-density nanoelectronic devices beyond the scaling limit of top-down device fabrication processes.

  4. Bottom-up synthesis of ordered metal/oxide/metal nanodots on substrates for nanoscale resistive switching memory

    Science.gov (United States)

    Han, Un-Bin; Lee, Jang-Sik

    2016-01-01

    The bottom-up approach using self-assembled materials/processes is thought to be a promising solution for next-generation device fabrication, but it is often found to be not feasible for use in real device fabrication. Here, we report a feasible and versatile way to fabricate high-density, nanoscale memory devices by direct bottom-up filling of memory elements. An ordered array of metal/oxide/metal (copper/copper oxide/copper) nanodots was synthesized with a uniform size and thickness defined by self-organized nanotemplate mask by sequential electrochemical deposition (ECD) of each layer. The fabricated memory devices showed bipolar resistive switching behaviors confirmed by conductive atomic force microscopy. This study demonstrates that ECD with bottom-up growth has great potential to fabricate high-density nanoelectronic devices beyond the scaling limit of top-down device fabrication processes. PMID:27157385

  5. Aqueous Chemical Solution Deposition of Novel, Thick and Dense Lattice-Matched Single Buffer Layers Suitable for YBCO Coated Conductors: Preparation and Characterization

    Directory of Open Access Journals (Sweden)

    Isabel van Driessche

    2012-09-01

    Full Text Available In this work we present the preparation and characterization of cerium doped lanthanum zirconate (LCZO films and non-stoichiometric lanthanum zirconate (LZO buffer layers on metallic Ni-5% W substrates using chemical solution deposition (CSD, starting from aqueous precursor solutions. La2Zr2O7 films doped with varying percentages of Ce at constant La concentration (La0.5CexZr1−xOy were prepared as well as non-stoichiometric La0.5+xZr0.5−xOy buffer layers with different percentages of La and Zr ratios. The variation in the composition of these thin films enables the creation of novel buffer layers with tailored lattice parameters. This leads to different lattice mismatches with the YBa2Cu3O7−x (YBCO superconducting layer on top and with the buffer layers or substrate underneath. This possibility of minimized lattice mismatch should allow the use of one single buffer layer instead of the current complicated buffer architectures such as Ni-(5% W/LZO/LZO/CeO2. Here, single, crack-free LCZO and non-stoichiometric LZO layers with thicknesses of up to 140 nm could be obtained in one single CSD step. The crystallinity and microstructure of these layers were studied by XRD, and SEM and the effective buffer layer action was studied using XPS depth profiling.

  6. Three-dimensional noble-metal nanostructure: A new kind of substrate for sensitive, uniform, and reproducible surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Surface-enhanced Raman spectroscopy (SERS) is a powerful vibrational spectroscopy technique for highly sensitive structural detection of low concentration analyte. The SERS activities largely depend on the topography of the substrate. In this review, we summarize the recent progress in SERS substrate, especially focusing on the three-dimensional (3D) noble-metal substrate with hierarchical nanostructure. Firstly, we introduce the background and general mechanism of 3D hierarchical SERS nanostructures. Then, a systematic overview on the fabrication, growth mechanism, and SERS property of various noble-metal substrates with 3D hierarchical nanostructures is presented. Finally, the applications of 3D hierarchical nanostructures as SERS substrates in many fields are discussed. (invited review — international conference on nanoscience and technology, china 2013)

  7. Corrosion Monitoring of Flexible Metallic Substrates for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Trystan Watson

    2013-01-01

    Full Text Available Two techniques for monitoring corrosion within a dye-sensitized solar cell (DSC system are presented, which enable continuous, high sensitivity, in situ measurement of electrolyte breakdown associated with DSCs fabricated on metals. The first method uses UV/Vis reflectance spectrophotometry in conjunction with encapsulation cells, which incorporate a 25 μm thick electrolyte layer, to provide highly resolved triiodide absorption data. The second method uses digital image capture to extract colour intensity data. Whilst the two methods provide very similar kinetic data on corrosion, the photographic method has the advantage that it can be used to image multiple samples in large arrays for rapid screening and is also relatively low cost. This work shows that the triiodide electrolyte attacks most metals that might be used for structural applications. Even a corrosion resistant metal, such as aluminium, can be induced to corrode through surface abrasion. This result should be set in the context with the finding reported here that certain nitrogen containing heterocyclics used in the electrolyte to enhance performance also act as corrosion inhibitors with significant stabilization for metals such as iron. These new techniques will be important tools to help develop corrosion resistant metal surfaces and corrosion inhibiting electrolytes for use in industrial scale devices.

  8. Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sujan, G.K., E-mail: sgkumer@gmail.com; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Afifi, A.B.M., E-mail: amalina@um.edu.my

    2014-11-15

    Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu{sub 6}Sn{sub 5} from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping

  9. Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

    International Nuclear Information System (INIS)

    Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu6Sn5 from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping of flux with

  10. Growth of ZnO nanowires through thermal oxidation of metallic zinc films on CdTe substrates

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, O., E-mail: oscar@fmc.uva.es [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011, Valladolid (Spain); Hortelano, V.; Jimenez, J. [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011, Valladolid (Spain); Plaza, J.L.; Dios, S. de; Olvera, J.; Dieguez, E. [Laboratorio de Crecimiento de Cristales, Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Fath, R.; Lozano, J.G.; Ben, T.; Gonzalez, D. [Dpto. Ciencia de los Materiales e Ingenieria Metalurgica y Q.I., Facultad de Ciencias, Apdo. 40, 11510 Puerto Real, Cadiz (Spain); Mass, J. [Dpto. de Fisica, Universidad del Norte, Km.5 Via Puerto Colombia, Barranquilla (Colombia)

    2011-04-28

    Research highlights: > ZnO nanowires grown from thermal Zn oxidation. > TEM reveals high quality thin nanowires several microns long. > New phase formation at long oxidation time. > Good spectroscopic properties measured by Raman, Photo and Cathodoluminsecence spectroscopies. - Abstract: <112-bar 0> wurtzite ZnO nanowires (NWs) have been obtained by oxidizing in air at 500 deg. C thermally evaporated Zn metal films deposited onto CdTe substrates. The presence of Cd atoms from the substrate on the ZnO seeding layer and NWs seems to affect the growth of the NWs. The effects of the oxidation time on the structural and optical properties of the NWs are described in detail. It is shown that the NWs density decreases and their length increases when increasing the oxidation time. Thicker Zn layers result in thinner and longer ZnO NWs. Very long oxidation times also lead to the formation of a new CdO phase which is related to the partial destruction and quality reduction of the NWs. The possible process for ZnO NW formation on CdTe substrates is discussed.

  11. Roll-to-Roll Encapsulation of Metal Nanowires between Graphene and Plastic Substrate for High-Performance Flexible Transparent Electrodes.

    Science.gov (United States)

    Deng, Bing; Hsu, Po-Chun; Chen, Guanchu; Chandrashekar, B N; Liao, Lei; Ayitimuda, Zhawulie; Wu, Jinxiong; Guo, Yunfan; Lin, Li; Zhou, Yu; Aisijiang, Mahaya; Xie, Qin; Cui, Yi; Liu, Zhongfan; Peng, Hailin

    2015-06-10

    Transparent conductive film on plastic substrate is a critical component in low-cost, flexible, and lightweight optoelectronics. Industrial-scale manufacturing of high-performance transparent conductive flexible plastic is needed to enable wide-ranging applications. Here, we demonstrate a continuous roll-to-roll (R2R) production of transparent conductive flexible plastic based on a metal nanowire network fully encapsulated between graphene monolayer and plastic substrate. Large-area graphene film grown on Cu foil via a R2R chemical vapor deposition process was hot-laminated onto nanowires precoated EVA/PET film, followed by a R2R electrochemical delamination that preserves the Cu foil for reuse. The encapsulated structure minimized the resistance of both wire-to-wire junctions and graphene grain boundaries and strengthened adhesion of nanowires and graphene to plastic substrate, resulting in superior optoelectronic properties (sheet resistance of ∼8 Ω sq(-1) at 94% transmittance), remarkable corrosion resistance, and excellent mechanical flexibility. With these advantages, long-cycle life flexible electrochromic devices are demonstrated, showing up to 10000 cycles. PMID:26020567

  12. Metallic substrate materials for thin film oxygen transport membranes for application in a fossil power plant

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Y.; Baumann, S.; Sebold, D.; Meulenberg, W.A.; Stoever, D. [Forschungszentrum Juelich GmbH (DE). Inst. fuer Energieforschung (IEF) - IEF-1 Materials Synthesis and Processing

    2010-07-01

    La{sub 0.58}Sr{sub 0.4}CO{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCF58428) and Ba{sub 0.5}Sr{sub 0.5}CO{sub 0.8}Fe{sub 3-{delta}} (BSCF5582) exhibit high oxygen permeability due to their high ionic and electronic conductivity. For this reason they are under discussion for application in oxygen transport membranes (OTMs) in zero-emission power plants using oxyfuel technology. A thin film membrane which can increase the oxygen flux is beneficial and a structural substrate is required. Two types of Ni-base alloys were studied as substrate material candidates with a number of advantages, such as high strength, high temperature stability, easy joining and similar thermal expansion coefficient to the selected perovskite materials. Chemical compositions and thermal expansion coefficients of Ni-base alloys were measured in this study. LSCF58428 and BSCF5582 layers were screen printed on Ni-based alloys and co-fired at high temperature in air. The microstructure and element analysis of samples were characterized by scanning electron microscopy (SEM and EDX). A Ni-base alloy, MCrAlY, with a high Al content was the most suitable substrate material, and showed better chemical compatibility with perovskite materials at high temperature than Hastelloy X, which is a chromia-forming Ni-base alloy. A reaction occurred between Sr in the perovskite and the alumina surface layers on MCr-AlY. However, the reaction zone did not increase in thickness during medium-term annealing at 800 C in air. Hence, it is expected that this reaction will not prevent the application of MCr-AlY as a substrate material. (orig.)

  13. Towards an electroless deposition of gold on metallic substrates using ionic liquids as electrolytes

    OpenAIRE

    Sá, A. I. Correia de; Quaresma, S.; Eugénio, S.; Rangel, C. M.; Vilar, Rui

    2010-01-01

    Recent research has suggested a number of applications for gold in fuel cells and related hydrogen fuel processing, which include coatings for light weight corrosion resistance bipolar plates and the incorporation of gold as catalyst to provide improvements in electrode conductivity, among others. This paper reports on the electroless deposition of gold on copper substrates from a HAuCl4.3H2O solution in 1-butyl-1-methylpyrrolidinium dicyanamide (BMP-DCA), in normal atmospheric conditions. Th...

  14. Ceramic on Metal Substrates Produced by Plasma Spraying for Thick Film Technology

    OpenAIRE

    Lech Pawłowski; Leszek Gołonka

    1983-01-01

    The arc plasma spraying process was applied to obtain ceramic coatings on stainless steel substrates. The outer coatings were formed from pure alumina or alumina + 2 wt. % titania mixture. The nichrome intermediate coating was applied to increase adhesion of ceramic coating to stainless steel. The X-ray analysis, metallographic and SEM investigations of the sprayed coatings were also carried out. The effect of interaction of thick film conductor and resistor compositions was studied. Conducto...

  15. Laser engineered multilayer coating of biphasic calcium phosphate/titanium nanocomposite on metal substrates.

    Science.gov (United States)

    Zhang, Martin Yi; Ye, Chang; Erasquin, Uriel Joseph; Huynh, Toan; Cai, Chengzhi; Cheng, Gary J

    2011-02-01

    In this work, laser coating of biphasic calcium phosphate/titanium (BCP/Ti) nanocomposite on Ti-6Al-4 V substrates was developed. A continuous wave neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was used to form a robust multilayer of BCP/Ti nanocomposite starting from hydroxyapatite and titanium nanoparticles. In this process, low power coating is realized because of the strong laser-nanoparticle interaction and good sinterability of nanosized titanium. To guide the optimization of laser processing conditions for the coating process, a multiphysics model coupling electromagnetic module with heat transfer module was developed. This model was validated by laser coating experiments. Important features of the coated samples, including microstructures, chemical compositions, and interfacial bonding strength, were characterized. We found that a multilayer of BCP, consisting of 72% hydroxyapatite (HA) and 28% beta-tricalcium phosphate (β-TCP), and titanium nanocomposite was formed on Ti-6Al-4 V substrates. Significantly, the coating/substrate interfacial bonding strength was found to be two times higher than that of the commercial plasma sprayed coatings. Preliminary cell culture studies showed that the resultant BCP/Ti nanocomposite coating supported the adhesion and proliferation of osteoblast-like UMR-106 cells. PMID:21207950

  16. Liquid phase deposition methods monitoring techniques influence for solid substrates and thin metal oxide films properties

    Directory of Open Access Journals (Sweden)

    A.V. Valiulis

    2007-09-01

    Full Text Available Purpose: Liquid phase deposition (LPD method is a useful method to create thin oxide films from aqueous solutions under ambient conditions. Deposition of ceramic layers on polymers is a technological challenge because of polymer sensitivity to chemicals and high temperature processing.Design/methodology/approach: The work attempts to elucidate the role of the substrate during LPD of TiO2 films by using Kapton with different types of surface treatments.Findings: Was found that small differences in pH, temperature, and solution composition can lead to dramatic differences in the film’s crystallinity, adherence, and growth rate. Thin films are very smooth, uniform with small amount of cracks.Research limitations/implications: Independent of technique and substrate, film thicker than a few hundred nm exhibited cracks, attributed to stresses that result during drying of the film.Originality/value: Techniques for monitoring the surface chemistry of the solid substrate and the deposited ceramic film have been developed.

  17. Chemical approach to the deposition of textured CeO2 buffer layers based on sol gel dip coating

    International Nuclear Information System (INIS)

    The widespread use of vacuum techniques for the development of coated conductors, in which buffer and superconducting (REBa2Cu3O7-δ) layers are deposited epitaxially on a substrate, is well established in the research environment. However, obtaining uninterrupted deposition at high speed, increasing flexibility in composition and in film thickness and attaining independence of geometric constraints are areas in which many vacuum techniques will need sustained development in order to answer industrial demands. This work describes the deposition of textured CeO2 buffer layers based on sol gel dip coating under atmospheric environment and from aqueous precursor materials. Research has been performed towards the deposition of CeO2-buffer layers using the amorphous citrate method on sapphire substrates and Ni-W foils. Coating is performed using the dip-coating technique, which allows extension to a continuous system. The withdrawal speed and the thermal treatment have been optimised in order to obtain highly oriented (001) layers exhibiting a smooth and crack-free morphology both on ceramic and metallic substrates. From the results it was concluded that sintering atmosphere and sintering temperature play a crucial role in the growth mechanism. This study describes the structural and morphological analysis of the thin layer with special attention to the difference between ceramic and metallic substrates. (orig.)

  18. Can a carbon nano-coating resist metallic phase transformation in silicon substrate during nanoimpact?

    OpenAIRE

    Goel, Saurav; Agrawal, Anupam; Nadimul H. Faisal

    2014-01-01

    Nanomechanical response of a silicon specimen coated with a sp3 crystalline carbon coating (1.8 nm thickness) was investigated using MD simulation. A sharp conical rigid tip was impacted at the speed of 50 m/sec up to a depth of ~80% of the coating thickness. Unlike pure silicon specimen, no metallic phase transformation was observed i.e. a thin coating was able to resist Si-I to Si-II metallic phase transformation signifying that the coating could alter the stress distribution and thereby th...

  19. Application of carbohydrate polymers as corrosion inhibitors for metal substrates in different media: A review.

    Science.gov (United States)

    Umoren, Saviour A; Eduok, Ubong M

    2016-04-20

    Naturally occurring polysaccharides are biopolymers existing as products of biochemical processes in living systems. A wide variety of them have been employed for various material applications; as binders, coatings, drug delivery, corrosion inhibitors etc. This review describes the application of some green and benign carbohydrate biopolymers and their derivatives for inhibition of metal corrosion. Their modes and mechanisms of protection have also been described as directly related to their macromolecular weights, chemical composition and their unique molecular and electronic structures. For instance, cellulose and chitosan possess free amine and hydroxyl groups capable of metal ion chelation and their lone pairs of electrons are readily utilized for coordinate bonding at the metal/solution interface. Some of the carbohydrate polymers reviewed in this work are either pure or modified forms; their grafted systems and nanoparticle composites with multitude potentials for metal protection applications have also been highlighted. Few inhibitors grafted to introduce more compact structures with polar groups capable of increasing the total energy of the surface have also been mentioned. Exudate gums, carboxymethyl and hydroxyethyl cellulose, starch, pectin and pectates, substituted/modified chitosans, carrageenan, dextrin/cyclodextrins and alginates have been elaborately reviewed, including the effects of halide additives on their anticorrosion performances. Aspects of computational/theoretical approach to corrosion monitoring have been recommended for future studies. This non-experimental approach to corrosion could foster a better understanding of the corrosion inhibition processes by correlating actual inhibition mechanisms with molecular structures of these carbohydrate polymers. PMID:26876859

  20. Biaxially aligned YSZ and CeO2 buffer layers on hastelloy prepared by magnetron IBAD

    International Nuclear Information System (INIS)

    Full text: The development of high-current, flexible superconducting YBCO tapes is based on a metal substrates overcoated with a biaxially aligned oxide buffer layer to serve as a template for the epitaxial growth of c-axis oriented Yba2Cu3O7 thin films. A secondary function of the buffer is to act as a diffusion barrier to metal species to prevent them from poisoning the superconducting film. Widely studied oxide buffer layers include yttria-stabilised zirconia (YSZ) and cerium oxide (CeO2) produced by ion-beam-assisted deposition (IBAD). We have combined IBAD with magnetron sputtering to deposit biaxially aligned YSZ and CeO2 on Hastelloy C276 substrates held at room temperature. The ion beam is directed at 55deg to the normal of the film plane. In addition, we achieved room temperature epitaxial growth of CeO2 films on IBAD YSZ films by bias sputtering to form biaxially aligned CeO2/YSZ bilayers. The crystalline quality and inplane orientation of the films (200 nm thick) were investigated by x-ray diffraction techniques including ω and φ scans and pole figures. The IBAD YSZ and CeO2 films have a (111) pole in the ion beam direction with a full width at half maximum, FWHM = 24 - 30 deg; the CeO2/YSZ bilayer is similarly aligned with FWHM = 32 deg

  1. Tunable surface plasmon polaritons in metal-strip waveguides with magnetized semiconductor substrates in Voigt configuration

    Science.gov (United States)

    Mathew, Gishamol; Mathew, Vincent

    2012-05-01

    The properties of surface plasmon polaritons (SPPs) in a magnetically tunable strip waveguide geometry comprising of a metal film of finite width deposited on a magnetized semiconductor and covered by an isotropic dielectric material were studied in Voigt configuration. The method of lines was used to compute the dispersion relation of fundamental modes, and the dependence of the propagation constant on metal film dimensions, material parameters and biasing magnetic field was considered. The bounded SPPs are nonreciprocal with respect to the direction of the biasing magnetic field, producing a nonreciprocal phase shift of the order of 2-18 rad mm-1 at a wavelength of excitation 1.55 μm. Moreover, controlled propagation of SPP modes and their effective tuning are possible in this strip geometry, which enables the design and development of tunable optoelectronic devices.

  2. Ultra-Thin Deformable Silicon Substrates with Lateral Segmentation and Flexible Metal Interconnect

    OpenAIRE

    Zoumpouidis, T.; Wang, L.; Bartek, M.; Jansen, K.M.B.; Ernst, L.J.

    2007-01-01

    Our progress in developing technology modules for deformable single-crystalline-silicon electronics is presented in this contribution. Additional deformability/reliability is accomplished by modifications of the previously reported ultra-thin and flexible CIRCONFLEX technology (1). The flexibility is added in the last steps of the process flow using a combination of lateral segmentation and flexible metal interconnects. The post-processing nature of the added mechanical flexibility is thought...

  3. Metal nanoparticle-enhanced room temperature phosphorescence of diiodofluorescein on the filter paper substrate

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Metal-enhanced room temperature phosphorescence of diiodofluorescein was first observed on filter paper surface.The phosphorescence intensity is 2.5-fold brighter from diiodofluorescein on silver nanoparticles-deposited filter paper as compared with an identical control sample without silver nanoparticles.Furthermore,enhanced absorption was also observed for the same system.Our findings suggest that both singlet and triplet states can couple to surface plasmons and enhance phosphorescence quantum yields ...

  4. Effect of substrate concentration on the bioleaching of heavy metals from sewage sludge

    Institute of Scientific and Technical Information of China (English)

    CHEN Ying-xu; HUA Yu-mei; ZHANG Shao-hui

    2004-01-01

    The effect of elemental sulfur concentration on bioleaching of Cu, Zn and Pb and loss of fertilizer value from sewage sludge was investigated in flasks by batch experiments. The results showed that the ultimate pH of sludges with 3-5 g/L of sulfur added was about 1.3 and the production of SO42- had good correlation with the elemental sulfur concentration. The sensitivity of removal efficiency of metals to sulfur concentration was: Pb>Cu>Zn. The sulfur concentration except for 3-5 g/L had significant effect on the solubilization of Cu, Pb and Zn. The highest solubilization efficiency for sludge with 3 g/L of sulfur was 87.86% for Cu, 32.72% for Pb and 92.14% for Zn, which could make the treated sludge easily meet the metal limitations for land application. The sulfur concentration of 3 g/L was enough for the solubilization of all three heavy metals. The influence of sulfur concentration on solubilization of total nitrogen and potassium from sludge was negligible, but that on solublization of total phosphorus was of great importance. The loss of nitrogen, phosphorus and potassium of sludge with 3 g/L of sulfur by bioleaching was 38.2%, 52.1% and 42.8% respectively, and the sludge still remained satisfactory fertilizer value after bioleaching.

  5. Influence of Temporary Cements on the Bond Strength of Self-Adhesive Cement to the Metal Coronal Substrate.

    Science.gov (United States)

    Peixoto, Raniel Fernandes; De Aguiar, Caio Rocha; Jacob, Eduardo Santana; Macedo, Ana Paula; De Mattos, Maria da Gloria Chiarello; Antunes, Rossana Pereira de Almeida

    2015-01-01

    This research evaluated the influence of temporary cements (eugenol-containing [EC] or eugenol-free [EF]) on the tensile strength of Ni-Cr copings fixed with self-adhesive resin cement to the metal coronal substrate. Thirty-six temporary crowns were divided into 4 groups (n=9) according to the temporary cements: Provy, Dentsply (eugenol-containing), Temp Cem, Vigodent (eugenol-containing), RelyX Temp NE, 3M ESPE (eugenol-free) and Temp Bond NE, Kerr Corp (eugenol-free). After 24 h of temporary cementation, tensile strength tests were performed in a universal testing machine at a crosshead speed of 0.5 mm/min and 1 kN (100 kgf) load cell. Afterwards, the cast metal cores were cleaned by scraping with curettes and air jet. Thirty-six Ni-Cr copings were cemented to the cast metal cores with self-adhesive resin cement (RelyX U200, 3M ESPE). Tensile strength tests were performed again. In the temporary cementation, Temp Bond NE (12.91 ± 2.54) and Temp Cem (12.22 ± 2.96) presented the highest values of tensile strength and were statistically similar to each other (p>0.05). Statistically significant difference (pcementation of Ni-Cr copings with self-adhesive resin cement. In addition, Temp Cem (120.68 ± 48.27) and RelyX Temp NE (103.04 ± 26.09) showed intermediate tensile strength values. In conclusion, the Provy eugenol-containing temporary cement was associated with the highest bond strength among the resin cements when Ni-Cr copings were cemented to cast metal cores. However, the eugenol cannot be considered a determining factor in increased bond strength, since the other tested cements (1 eugenol-containing and 2 eugenol-free) were similar. PMID:26963209

  6. Recrystallization Texture and Microstructure of Metal Substrate for Y123 Coated Superconductor

    Institute of Scientific and Technical Information of China (English)

    刘慧舟; 史锴; 杨坚; 袁冠森

    2003-01-01

    The cube textured pure Ni and non-magnetic Cu-Ni tapes were obtained by rolling and recrystallization, and these tapes are suitable as substrates of the second generation high temperature superconducting tape. The texture of tapes was studied using Orientation Distribution Function (ODF) and φ-scans. The results indicate that sharp cube texture of Cu0.70Ni0.30 and pure Ni was formed at 1000 ℃ and that of Cu0.85Ni0.15 was formed at 900 ℃. The intensities of cube texture differ from each other. Uniform equiaxial crystallites are formed in all the tapes and the size of Cu0.85Ni0.15 is larger than that of Cu0.70Ni0.30 and pure Ni. Annealing twin is formed in Cu0.85Ni0.15 and Cu0.70Ni0.30.

  7. Tension assisted metal transfer of graphene for Schottky diodes onto wafer scale substrates

    Science.gov (United States)

    Lee, Jooho; Lee, Su Chan; Kim, Yongsung; Heo, Jinseong; Lee, Kiyoung; Lee, Dongwook; Kim, Jaekwan; Lee, Sunghee; Lee, Chang Seung; Nam, Min Sik; Jun, Seong Chan

    2016-02-01

    We developed an effective graphene transfer method for graphene/silicon Schottky diodes on a wafer as large as 6 inches. Graphene grown on a large scale substrate was passivated and sealed with a gold layer, protecting graphene from any possible contaminant and keeping good electrical contact. The Au/graphene was transferred by the tension-assisted transfer process without polymer residues. The gold film itself was used directly as the electrodes of a Schottky diode. We demonstrated wafer-scale integration of graphene/silicon Schottky diode using the proposed transfer process. The transmission electron microscopy analysis and relatively low ideality factor of the diodes indicated fewer defects on the interface than those obtained using the conventional poly(methyl methacrylate)-assisted transfer method. We further demonstrated gas sensors as an application of graphene Schottky diodes.

  8. Silicene on metal substrates: A first-principles study on the emergence of a hierarchy of honeycomb structures

    International Nuclear Information System (INIS)

    Experimental studies have reported several types of Si monolayer structures that are formed on metal surfaces. These structures typically show the topology of a honeycomb bonding network, but differ in terms of corrugation and surface coverage. Using first-principles calculations, we identify atomic-scale mechanisms that underlie the appearance of different configurations as coverage increases during Si deposition on silver. The key point is that any extra Si adatoms that land on preformed silicene films can be incorporated in the honeycomb network and form bonds with underlying Ag atoms. As a result, the corrugation profile changes, giving rise to varying overlayer geometries. We also show that the same set of mechanisms control the appearance of silicene films on an iridium substrate. The results address available experimental data, but also probe the stability and properties of silicene wetting films that have not been observed yet.

  9. Recent advances and perspectives in analytical methodologies for monitoring the bioavailability of trace metals in environmental solid substrates

    DEFF Research Database (Denmark)

    Miró, Manuel; Hansen, Elo Harald

    2006-01-01

    In the last decades, researchers have realised that the impact of trace elements (TE) in environmental solid substrates on ecological systems and biota cannot be ascertained appropriately by means of total metal content measurements. Assessment of TE chemical forms, types of binding and reactivity...... of their associations with particulate forms has, thus, been commonly performed via batch-wise equilibrium-based sequential extraction fractionation methods able to discern TE bound to different soil-phase compartments. In this paper, novel analytical strategies for monitoring the mobility......, bioavailability and the eventual impact of anthropogenic TE in environmental solids are addressed. The potential of passive dosimeters based on microdialysis sampling for on-site, real-time monitoring of chemical contaminants in pore soil solution is thoroughly discussed and critically compared with active...

  10. Effect of Si interlayer thickness and post-metallization annealing on Ge MOS capacitor on Ge-on-Si substrate

    International Nuclear Information System (INIS)

    We demonstrated the effect of post-metallization annealing and Si interlayer thickness on Ge MOS capacitor on Ge-on-Si substrate with HfO2/TaN. Ge outdiffusion and oxygen interdiffusion were completely suppressed by thick Si interfacial layer. As a result, formation of insufficient low-k Ge oxides was effectively inhibited. It is confirmed that gate current of Si passivated Ge MOS was decreased by Si IL and decrease of gate current, Jg is saturated after Si IL of 2 nm. It was also observed that when Si IL is thick enough to restrict Ge outdiffusion, increase of Jg is not due to the temperature-induced Ge outdiffusion but due to the partial crystallization of HfO2 at higher annealing temperature

  11. Characterization of AlInN/AlN/GaN Heterostructures with Different AlN Buffer Thickness

    Science.gov (United States)

    Çörekçi, S.; Dugan, S.; Öztürk, M. K.; Çetin, S. Ş.; Çakmak, M.; Özçelik, S.; Özbay, E.

    2016-07-01

    Two AlInN/AlN/GaN heterostructures with 280-nm- and 400-nm-thick AlN buffer grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and Hall-effect measurements. The symmetric (0002) plane with respect to the asymmetric (10bar{1}2) plane in the 280-nm-thick AlN buffer has a higher crystal quality, as opposed to the 400-nm-thick buffer. The thinner buffer improves the crystallinity of both (0002) and (10bar{1}2) planes in the GaN layers, it also provides a sizeable reduction in dislocation density of GaN. Furthermore, the lower buffer thickness leads to a good quality surface with an rms roughness of 0.30 nm and a dark spot density of 4.0 × 108 cm-2. The optical and transport properties of the AlInN/AlN/GaN structure with the relatively thin buffer are compatible with the enhancement in its structural quality, as verified by XRD and AFM results.

  12. Metal-assisted exfoliation (MAE): green, roll-to-roll compatible method for transferring graphene to flexible substrates

    International Nuclear Information System (INIS)

    Graphene is expected to play a significant role in future technologies that span a range from consumer electronics, to devices for the conversion and storage of energy, to conformable biomedical devices for healthcare. To realize these applications, however, a low-cost method of synthesizing large areas of high-quality graphene is required. Currently, the only method to generate large-area single-layer graphene that is compatible with roll-to-roll manufacturing destroys approximately 300 kg of copper foil (thickness = 25 μm) for every 1 g of graphene produced. This paper describes a new environmentally benign and scalable process of transferring graphene to flexible substrates. The process is based on the preferential adhesion of certain thin metallic films to graphene; separation of the graphene from the catalytic copper foil is followed by lamination to a flexible target substrate in a process that is compatible with roll-to-roll manufacturing. The copper substrate is indefinitely reusable and the method is substantially greener than the current process that uses relatively large amounts of corrosive etchants to remove the copper. The sheet resistance of the graphene produced by this new process is unoptimized but should be comparable in principle to that produced by the standard method, given the defects observable by Raman spectroscopy and the presence of process-induced cracks. With further improvements, this green, inexpensive synthesis of single-layer graphene could enable applications in flexible, stretchable, and disposable electronics, low-profile and lightweight barrier materials, and in large-area displays and photovoltaic modules. (paper)

  13. Metal-assisted exfoliation (MAE): green, roll-to-roll compatible method for transferring graphene to flexible substrates

    Science.gov (United States)

    Zaretski, Aliaksandr V.; Moetazedi, Herad; Kong, Casey; Sawyer, Eric J.; Savagatrup, Suchol; Valle, Eduardo; O'Connor, Timothy F.; Printz, Adam D.; Lipomi, Darren J.

    2015-01-01

    Graphene is expected to play a significant role in future technologies that span a range from consumer electronics, to devices for the conversion and storage of energy, to conformable biomedical devices for healthcare. To realize these applications, however, a low-cost method of synthesizing large areas of high-quality graphene is required. Currently, the only method to generate large-area single-layer graphene that is compatible with roll-to-roll manufacturing destroys approximately 300 kg of copper foil (thickness = 25 μm) for every 1 g of graphene produced. This paper describes a new environmentally benign and scalable process of transferring graphene to flexible substrates. The process is based on the preferential adhesion of certain thin metallic films to graphene; separation of the graphene from the catalytic copper foil is followed by lamination to a flexible target substrate in a process that is compatible with roll-to-roll manufacturing. The copper substrate is indefinitely reusable and the method is substantially greener than the current process that uses relatively large amounts of corrosive etchants to remove the copper. The sheet resistance of the graphene produced by this new process is unoptimized but should be comparable in principle to that produced by the standard method, given the defects observable by Raman spectroscopy and the presence of process-induced cracks. With further improvements, this green, inexpensive synthesis of single-layer graphene could enable applications in flexible, stretchable, and disposable electronics, low-profile and lightweight barrier materials, and in large-area displays and photovoltaic modules.

  14. High mobility field effect transistors of SnOx on glass substrates made by reactive sputtering of Sn metal

    Science.gov (United States)

    Ju, Chanjong; Park, Chulkwon; Yang, Hyeonseok; Kim, Useong; Kim, Young Mo; Char, Kookrin

    2015-03-01

    We report on the electrical properties of SnOx thin films and the performance of their field effect transistors on glass substrates made by reactive sputtering of a Sn metal target. We investigated the electrical properties of SnOx films as a function of the oxygen pressure. The mobility of the SnOx films on glass substrates after post-deposition annealing at 400 C was as high as 15.3 cm2/Vs while its carrier density was 4.42 × 1018 cm-3. By x-ray diffraction, we have found that the films are mixture of SnO and SnO2 phases, suggesting possibility of further enhancement of the electrical properties if the phase can be controlled. Nevertheless, we will report on the performance of thin film transistors using polycrystalline SnOx as the channel layer and the atomic-layer-deposited AlOx and HfOx as the gate oxide.

  15. Influence of hydrogen on the structure and stability of ultra-thin ZnO on metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Bieniek, Bjoern [Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin (Germany); Hofmann, Oliver T. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin (Germany); Institut für Festkörperphysik, TU Graz, 8010 Graz (Austria); Rinke, Patrick, E-mail: patrick.rinke@aalto.fi [Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin (Germany); School of Science, Aalto University, FI-00076 Aalto (Finland)

    2015-03-30

    We investigate the atomic and electronic structure of ultra-thin ZnO films (1 to 4 layers) on the (111) surfaces of Ag, Cu, Pd, Pt, Ni, and Rh by means of density-functional theory. The ZnO monolayer is found to adopt an α-BN structure on the metal substrates with coincidence structures in good agreement with experiment. Thicker ZnO layers change into a wurtzite structure. The films exhibit a strong corrugation, which can be smoothed by hydrogen (H) adsorption. An H over-layer with 50% coverage is formed at chemical potentials that range from low to ultra-high vacuum H{sub 2} pressures. For the Ag substrate, both α-BN and wurtzite ZnO films are accessible in this pressure range, while for Cu, Pd, Pt, Rh, and Ni wurtzite films are favored. The surface structure and the density of states of these H passivated ZnO thin films agree well with those of the bulk ZnO(0001{sup ¯})-2×1-H surface.

  16. Versatile Oxidation Methods for Organic and Inorganic Substrates Catalyzed by Platinum-Group Metals on Carbons.

    Science.gov (United States)

    Sawama, Yoshinari; Asai, Shota; Monguchi, Yasunari; Sajiki, Hironao

    2016-02-01

    Platinum-group metals on activated carbon catalysts, represented by Pd/C, Ru/C, Rh/C, etc., are widely utilized to accomplish green and sustainable organic reactions due to their favorable features, such as easy handling, recoverability, and reusability. The efficient oxidation methods of various organic compounds using heterogeneous platinum-group metals on carbons with or without added oxidants are summarized in this Personal Account. The oxidation of internal alkynes into diketones was effectively catalyzed by Pd/C in the presence of dimethyl sulfoxide and molecular oxygen or pyridine N-oxide. The Pd/C-catalyzed mild combustion of gaseous hydrogen with molecular oxygen provided hydrogen peroxide, which could be directly utilized for the oxidation of sulfide derivatives into sulfoxides. Furthermore, the Ru/C-catalyzed aerobic oxidation of primary and secondary alcohols gave the corresponding aldehydes and ketones, respectively. On the other hand, the dehydrogenative oxidation of secondary alcohols into ketones was achieved using Rh/C in water, and primary alcohols were effectively dehydrogenated by Pd/C in water under mildly reduced pressure to produce carboxylic acids. PMID:26666634

  17. The modulation effect of substrate doping on multi-node charge collection and single-event transient propagation in 90-nm bulk complementary metal-oxidesemiconductor technology

    Institute of Scientific and Technical Information of China (English)

    Qin Jun-Rui; Chen Shu-Ming; Liu Bi-Wei; Liu Zheng; Liang Bin; Du Yan-Kang

    2011-01-01

    Variation of substrate background doping will affect the charge collection of active and passive MOSFETs in complementary metal-oxide semiconductor (CMOS) technologies,which are significant for charge sharing,thus affecting the propagated single event transient pulsewidths in circuits.The trends of charge collected by the drain of a positive channel metal-oxide semiconductor (PMOS) and an N metal-oxide semiconductor (NMOS) are opposite as the substrate doping increases.The PMOS source will inject carriers after strike and the amount of charge injected will increase as the substrate doping increases,whereas the source of the NMOS will mainly collect carriers and the source of the NMOS can also inject electrons when the substrate doping is light enough.Additionally,it indicates that substrate doping mainly affects the bipolar amplification component of a single-event transient current,and has little effect on the drift and diffusion.The change in substrate doping has a much greater effect on PMOS than on NMOS.

  18. Effects of substrate temperature on the unusual non-Fermi liquid metal to insulator transition in perovskite SrIrO3 thin films

    OpenAIRE

    Biswas, Abhijit; Jeong, Yoon Hee

    2015-01-01

    Electronic transport has been investigated for strong spin-orbit coupled perovskite SrIrO3 thin films grown at various substrate temperatures. The electronic transport of the SrIrO3 films is found to be very sensitive to the growth parameters; in particular, the film can either be a metal or an insulator depending upon the substrate growth temperature. While all the metallic films show unusual sublinear temperature dependent non-Fermi liquid behaviors in resistivity, the insulating film grown...

  19. [Coating modification of anthracite substrates in vertical-flow constructed wetlands by LDHs synthesized from different metal compounds and the nitrogen removal efficiencies].

    Science.gov (United States)

    Zhang, Xiang-Ling; Guo, Lu; Chen, Jun-Jie; Liu, Xiao-Ting; Xu, Lu; Chen, Qiao-Zhen; Wang, Xiao-Xiao

    2014-08-01

    As one kind of vertical-flow constructed wetlands substrates, anthracite was selected in this experiment. LDHs (layered double hydroxides) were synthesized in alkaline conditions by co-precipitation of different kinds of metal compounds, such as CaCl2, ZnCl2, MgCl2, FeCl3, AlCl3, CoCl3. The synthesized LDHs were in-situ coated onto the surface of anthracite substrate to achieve the aim of modification. Simulated test columns were constructed to study the nitrogen removal efficiency of the urban sewage using the original anthracite substrates and 9 kinds of modified anthracite substrates. The results showed that: LDHs synthesized by all the 9 different kinds of methods could effectively modify the anthracite substrate by in-situ coating. With Mg2+ involved in the synthesis of modified substrates, good TN and ammonia nitrogen removal efficiencies were observed. The modified anthracite substrates coated with MgCo-LDHs had the optimal performance with average TN and ammonia nitrogen removal efficiencies of higher than 80% and 85%, respectively. The ammonia nitrogen removal efficiencies by the modified anthracite substrates coated by LDHs reacted with Mg2+ and Fe3+ were also high. The ammonia nitrogen removal efficiencies by modified anthracite substrates coated with CaFe-LDHs and MgFe-LDHs were higher than 85%. PMID:25340214

  20. High-T(sub c) Edge-geometry SNS Weak Links on Silicon-on-sapphire Substrates

    Science.gov (United States)

    Hunt, B.; Foote, M.; Pike, W.; Barner, J.; Vasquez, R.

    1994-01-01

    High-quality superconductor/normal-metal/superconductor(SNS) edge-geometry weak links have been produced on silicon-on-sapphire (SOS) substrates using a new SrTiO(sub 3)/'seed layer'/cubic-zirconia (YS2) buffer system.

  1. Fabrication of periodic arrays of metallic nanoparticles by block copolymer templates on HfO2 substrates.

    Science.gov (United States)

    Frascaroli, Jacopo; Seguini, Gabriele; Spiga, Sabina; Perego, Michele; Boarino, Luca

    2015-05-29

    Block copolymer-based templates can be exploited for the fabrication of ordered arrays of metal nanoparticles (NPs) with a diameter down to a few nanometers. In order to develop this technique on metal oxide substrates, we studied the self-assembly of polymeric templates directly on the HfO₂ surface. Using a random copolymer neutralization layer, we obtained an effective HfO₂ surface neutralization, while the effects of surface cleaning and annealing temperature were carefully examined. Varying the block copolymer molecular weight, we produced regular nanoporous templates with feature size variable between 10 and 30 nm and a density up to 1.5 × 10¹¹ cm⁻². With the adoption of a pattern transfer process, we produced ordered arrays of Pt and Pt/Ti NPs with diameters of 12, 21 and 29 nm and a constant size dispersion (σ) of 2.5 nm. For the smallest template adopted, the NP diameter is significantly lower than the original template dimension. In this specific configuration, the granularity of the deposited film probably influences the pattern transfer process and very small NPs of 12 nm were achieved without a significant broadening of the size distribution. PMID:25948389

  2. Effect of EDTA washing of metal polluted garden soils. Part II: Can remediated soil be used as a plant substrate?

    Science.gov (United States)

    Jelusic, Masa; Vodnik, Dominik; Macek, Irena; Lestan, Domen

    2014-03-15

    In a field experiment on metal contaminated and EDTA-remediated soil we studied plant performance, mycorrhizal associations and prospects of potential re-use of remediated soil as a garden substrate. Two experimental plots of 4 × 1 × 0.3 m were filled, one with remediated and the other with original contaminated soil. Selected cultivars were rotated over the course of 16months. Pb, Zn, Cd and micronutrient plant uptake was measured and their phytoaccessibility was analyzed by the DTPA method. Plant fitness was assessed by chlorophyll fluorescence and gas exchange measurements and evaluation of root colonization were analyzed with mycorrhizal fungi. Remediation reduced Pb and Cd concentrations in roots, green parts and fruits in most of the plants. Phytoaccumulation of Zn was reduced in one half of the cultivars. Some plants suffered from Mn deficiency as total soil Mn was reduced 4-fold and phytoaccessibility of micronutrients Cu, Fe and Mn for 54, 26 and 79%, respectively. Plant biomass was reduced. Photosynthetic parameters of plants grown in original and remediated soil were similar, except for the reduction in Spinacia oleracea. The frequency of mycorrhizal colonization in the roots of Pisum sativum was reduced five-fold and no significant changes were found in Allium cepa roots. Remediation reduced plant uptake of Pb below the concentration stipulated by legislation. Measures to reduce plant accumulation of other toxic metals and to revitalize remediated soil are needed. PMID:24342493

  3. Fabrication of large-grained thin polycrystalline silicon films on foreign substrates by titanium-assisted metal-induced layer exchange

    Science.gov (United States)

    Antesberger, T.; Wassner, T. A.; Kashani, M.; Scholz, M.; Lechner, R.; Matich, S.; Stutzmann, M.

    2012-12-01

    Metal-induced layer exchange (MILE) is a well-known method to grow large-grained high quality polycrystalline silicon on foreign substrates. We have modified the commonly used layer stack by an additional titanium interfacial layer (substrate/metal/titanium/oxide/amorphous silicon). The resulting layer exchange process is called titanium-assisted metal-induced layer exchange (Ti.MILE). For the investigated metals, Al (Ti.ALILE) and Ag (Ti.AgILE), the additional Ti layer does not affect the overall layer exchange process but results in a strong enlargement of the grains in the resulting polycrystalline silicon layer up to 250 μm. We have investigated the influence of the titanium interfacial layer on the process dynamics and grain growth. Furthermore, the structural and optical properties of the resulting polycrystalline silicon layer are investigated by means of different analysis methods.

  4. Improved properties of barium strontium titanate thin films grown on copper foils by pulsed laser deposition using a self-buffered layer

    International Nuclear Information System (INIS)

    Ba0.6Sr0.4TiO3 (BST) films were deposited by pulsed laser deposition on copper foils with low-temperature self-buffered layers. The deposition conditions included a low oxygen partial pressure and a temperature of 700 °C to crystallize the films without the formation of secondary phases and substrate oxidation. The results from x-ray diffraction and scanning electron microscopy indicated that the microstructure of the BST films strongly depended on the growth temperature. The use of the self-buffered layer improved the dielectric properties of the deposited BST films. The leakage current density of the BST films on the copper foil was 4.4 × 10-9 A cm-2 and 3.3 × 10-6 A cm-2 with and without the self-buffered layer, respectively. The ferroelectric hysteresis loop for the BST thin film with buffer layer was slim, in contrast to the distorted loop observed for the film without the buffer layer. The permittivity (700) and dielectric loss tangent (0.013) of the BST film on the copper foil with self-buffered layer at room temperature were comparable to those of the film on metal and single-crystal substrates. (paper)

  5. Molten-Metal Droplet Deposition on a Moving Substrate in Microgravity: Aiding the Development of Novel Technologies for Microelectronic Assembly

    Science.gov (United States)

    Megaridis, C. M.; Bayer, I. S.; Poulikakos, D.; Nayagam, V.

    2002-01-01

    Driven by advancements in microelectronics manufacturing, this research investigates the oblique (non-axisymmetric) impact of liquid-metal droplets on flat substrates. The problem of interest is relevant to the development of the novel technology of on-demand dispension (printing) of microscopic solder deposits for the surface mounting of microelectronic devices. The technology, known as solder jetting, features on-demand deposition of miniature solder droplets (30 to 120 microns in diameter) in very fine, very accurate patterns using techniques analogous to those developed for the ink-jet printing industry. Despite its promise, severe limitations exist currently with regards to the throughput rates of the technology; some of these limitations are largely due to the lack of the capability for reliable prediction of solder bump positioning and shapes, especially under ballistic deposition conditions where the droplet impact phenomena are inherently three-dimensional. The study consists of a theoretical and an experimental component. The theoretical work uses a finite element formulation to simulate numerically the non-axisymmetric (3-D) fluid mechanics and heat transfer phenomena of a liquid solder droplet impacting at an angle alpha on a flat substrate. The work focuses on the pre-solidification regime. The modeling of the most challenging fluid mechanics part of the process has been completed successfully. It is based upon the full laminar Navier-Stokes equations employing a Lagrangian frame of reference. Due to the large droplet deformation, the surface (skin) as well as the volumetric mesh have to be regenerated during the calculations in order to maintain the high accuracy of the numerical scheme. The pressure and velocity fields are then interpolated on the newly created mesh. The numerical predictions are being tested against experiments, for cases where wetting phenomena are not important. For the impact parameters used in the example shown (We = 2.38, Fr

  6. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals

    OpenAIRE

    Liu, Yuanyue; Merinov, Boris V.; Goddard III, William A.

    2016-01-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same...

  7. Area estimate for buffer area of loading/unloading site for metal-concrete casks with BN-350 spent nuclear fuel

    International Nuclear Information System (INIS)

    Calculation results are presented for radiation fields induced by BN-350 spent nuclear fuel transported in seven-pack metal-concrete cask. The results are used to evaluate dose load on personnel and population at the cask loading/unloading operations. For the purpose of calculations, MCNP code was applied. (author)

  8. Buffer design 2012

    International Nuclear Information System (INIS)

    Posiva's spent nuclear fuel disposal is based on the KBS-3V concept and on the characteristics of the Olkiluoto site. In this concept single canisters containing spent nuclear fuel surrounded by a bentonite buffer are emplaced in individual vertical boreholes drilled in the floor of deposition tunnels in bedrock at about 420 m depth below ground level. Disk type bentonite blocks are installed at the bottom of the hole and on the top of the disposal canister. Ring type bentonite blocks surround the canisters. This report describes the detailed design of the buffer for a KBS-3V repository. The report presents the design basis, the reference design, and summarises the performance analyses carried out for the design. This report addresses aspects concerning the manufacture, quality control, mechanical strength, chemical resistance, thermal dimensioning, handling of buffer components and material ageing phenomena including the effect of radiation. Interaction of buffer and other engineered barriers are included in the study. The long-term evolution of the repository and its effective drivers are considered if they have an impact on the buffer performance but operational safety aspects are also included because they may affect long-term safety. (orig.)

  9. Aqueous Chemical Solution Deposition of Novel, Thick and Dense Lattice-Matched Single Buffer Layers Suitable for YBCO Coated Conductors: Preparation and Characterization

    OpenAIRE

    Isabel Van Driessche; Petra Lommens; Sigelinde van Steenberge; Vyshnavi Narayanan

    2012-01-01

    In this work we present the preparation and characterization of cerium doped lanthanum zirconate (LCZO) films and non-stoichiometric lanthanum zirconate (LZO) buffer layers on metallic Ni-5% W substrates using chemical solution deposition (CSD), starting from aqueous precursor solutions. La2Zr2O7 films doped with varying percentages of Ce at constant La concentration (La0.5CexZr1−xOy) were prepared as well as non-stoichiometric La0.5+xZr0.5−xOy buffer layers with different percentages of La a...

  10. Strain-driven synthesis of direction InAs nanowires in V-grooved trenches on Si using InP/GaAs buffer layers

    Science.gov (United States)

    Li, Shiyan; Zhou, Xuliang; Kong, Xiangting; Li, Mengke; Mi, Junping; Wang, Mengqi; Pan, Jiaoqing

    2016-09-01

    The catalyst-free metal organic vapor phase epitaxial growth of InAs nanowires on silicon (001) substrates is investigated by using selectively grown InP/GaAs buffer layers in V-grooved trenches. A strain-driven mechanism of self-aligned direction InAs nanowires growing is proposed and demonstrated by the transmission electron microscopy measurement. The morphology of InAs nanowires is tapered in diameter and exhibits a hexagonal cross-section. The defect-free InAs nanowire shows a pure zinc blende crystal structure and an epitaxial relationship with InP buffer layer.

  11. Effect of Adhesive Type on the Shear Bond Strength of Metal Brackets to Two Ceramic Substrates

    Directory of Open Access Journals (Sweden)

    Mohammad Sadegh Ahmad Akhoundi

    2014-04-01

    Full Text Available Increased number of adult patients requesting orthodontic treatment result in bonding bracket to ceramic restorations more than before. The aim of this study was to evaluate and compare the shear bond strength of orthodontic brackets bonded to two types of ceramic bases with conventional orthodontic bonding resin and a new nano-filled composite resin.Twenty four feldespathic porcelain and 24 lithium disilicate ceramic disks were fabricated. All of the samples were conditioned by sandblasting, hydrofluoric acid and silane. Maxillary incisor metal brackets were bonded to half of the disks in each group by conventional orthodontic bonding resin and the other half bonded with a nano-filled composite. The samples then were thermocycled for 2000 cycle between 5-55° C. Shear bond strength was measured and the mode of failure was examined. Randomly selected samples were also evaluated by SEM.The lowest bond strength value was found infeldespathic ceramic bonded by nano-filled composite (p<0.05. There was not any statistically significant difference between other groups regarding bond strength. The mode of failure in the all groups except group 1 was cohesive and porcelain damages were detected.Since less damages to feldspathic porcelain was observed when the nano-filled composite was used to bond brackets, the use of nano-filled composite resins can be suggested for bonding brackets to feldspathic porcelain restorations.

  12. An InGaAs graded buffer layer in solar cells

    International Nuclear Information System (INIS)

    This paper uses an InGaAs graded buffer layer to solve the problem of lattice mismatch and device performance degradation. In the graded buffer layer, we choose the ''transition layer'' and the ''cover layer'' to accommodate the 3.9% mismatch. No threading dislocations were observed in the uppermost part of the epitaxial layer stack when using a transmission electron microscope (TEM). We analyze the factors which influence the saturation current. Simulation data shows that the cells grown by metal organic vapor phase epitaxy (MOVPE) have considerable open circuit voltage, short circuit current, and photoelectric conversion efficiency. Finally we propose that InP may have great development potential as a substrate material. (semiconductor devices)

  13. A parallel buffer tree

    DEFF Research Database (Denmark)

    Sitchinava, Nodar; Zeh, Norbert

    2012-01-01

    We present the parallel buffer tree, a parallel external memory (PEM) data structure for batched search problems. This data structure is a non-trivial extension of Arge's sequential buffer tree to a private-cache multiprocessor environment and reduces the number of I/O operations by the number...... of available processor cores compared to its sequential counterpart, thereby taking full advantage of multicore parallelism. The parallel buffer tree is a search tree data structure that supports the batched parallel processing of a sequence of N insertions, deletions, membership queries, and range queries...... in the optimal OhOf(psortN + K/PB) parallel I/O complexity, where K is the size of the output reported in the process and psortN is the parallel I/O complexity of sorting N elements using P processors....

  14. Angular properties of pure and Ca-substituted YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} superconducting thin films grown on SrTiO{sub 3} and CeO{sub 2} buffered Al{sub 2}O{sub 3} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Augieri, A. [ENEA Research Center, Via E. Fermi 45, 00044 Frascati, Rome (Italy)], E-mail: augieri@frascati.enea.it; Celentano, G. [ENEA Research Center, Via E. Fermi 45, 00044 Frascati, Rome (Italy); Ciontea, L. [Technical university of Cluj-Napoca, Str. C. Daicoviciu 15, 3400 Cluj-Napoca (Romania); Galluzzi, V. [ENEA Research Center, Via E. Fermi 45, 00044 Frascati, Rome (Italy); Gambardella, U. [INFN-LNF, Via E. Fermi 40, 00044 Frascati, Rome (Italy); Halbritter, J. [IHM, FZK, Postfach 3640, 76021 Karlsruhe (Germany); Petrisor, T. [Technical university of Cluj-Napoca, Str. C. Daicoviciu 15, 3400 Cluj-Napoca (Romania); Rufoloni, A.; Vannozzi, A. [ENEA Research Center, Via E. Fermi 45, 00044 Frascati, Rome (Italy)

    2007-09-01

    In this work transport properties of superconducting 10 at.% Ca-substituted YBCO thin films grown on (1 0 0)-SrTiO{sub 3} single crystal substrate (STO) and superconducting pure and 10 at.% Ca-substituted YBCO thin films grown on CeO{sub 2} buffered Al{sub 2}O{sub 3} substrates (CAO) have been analyzed as a function of the temperature, applied magnetic field and angle between magnetic field direction and the direction normal to the film surfaces. Particularly, the angular analysis provides an easy way to discriminate between isotropic point defects and correlated pinning sites. Despite the intragrain pinning mechanisms remained unaffected by Ca substitution, a detrimental effect on grain boundary properties clearly emerged for 10 at.% Ca concentration. This effect is enhanced in sample grown on CeO{sub 2} buffered sapphire where a more disturbed grain boundary is expected resulting in an enhancement of the correlated pinning, already observed in pure YBCO films grown on CAO, and in a reduction of the intrinsic pinning efficiency.

  15. BaxSr1−xTi1.02O3 metal–insulator–metal capacitors on planarized alumina substrates

    NARCIS (Netherlands)

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Mauczok, R.; Keur, W.; Hueting, R.J.E.

    2010-01-01

    Nanocrystalline barium strontium titanate (BaxSr1−xTi1.02O3) thin films with a barium content of x=0.8, 0.9 and 1 have been fabricated in a metal–insulator–metal configuration on glass-planarized alumina substrates. Cost-effective processing measures have been utilized by using poly-crystalline alum

  16. LETTER TO THE EDITOR: Variation of adatom to substrate charge transfer value along the first-row transition metal series on Mo(110)

    Science.gov (United States)

    Magkoev, T. T.; Christmann, K.; Lecante, P.; Moutinho, A. M. C.

    2002-04-01

    Adsorption of the first-row transition 3d metals (Ti-Cu) on the atomically clean Mo(110) surface in ultra-high-vacuum conditions has been studied by Auger electron spectroscopy and work function measurements (Anderson method). In this letter it is shown that adsorption behaviour of the metals under consideration systematically changes along the 3d series. The observed correlation between the systematic change of the dipole moments and the values of the charge transfer from adatom to substrate along the period leads us to the conclusion that the metal 3d orbitals play an important role in the formation of the chemisorption bond.

  17. Final report on LDRD project: Low-cost Pd-catalyzed metallization technology for rapid prototyping of electronic substrates and devices

    Energy Technology Data Exchange (ETDEWEB)

    Chen, K.S.; Morgan, W.P.; Zich, J.L.

    1998-02-01

    A low-cost, thermally-activated, palladium-catalyzed metallization process was developed for rapid prototyping of polymeric electronic substrates and devices. The process was successfully applied in producing adhesiveless copper/polyimide laminates with high peel strengths and thick copper coating; copper/polyimide laminates are widely used in fabricating interconnects such as printed wiring boards (PWBs) and flexible circuits. Also successfully metallized using this low-cost metallization process were: (1) scaled-down models of radar-and-communication antenna and waveguide; (2) scaled-down model of pulsed-power-accelerator electrode; (3) three-dimensional micro-porous, open-cell vitreous carbon foams. Moreover, additive patterned metallization was successfully achieved by selectively printing or plotting the catalyst ink only on areas where metallization is desired, and by uniform thermal activation. Additive patterned metallization eliminates the time-consuming, costly and environmentally-unfriendly etching process that is routinely carried out in conventional subtractive patterned metallization. A metallization process via ultraviolet (UV) irradiation activation was also demonstrated. In this process palladium-catalyst solution is first uniformly coated onto the substrate. A masking pattern is used to cover the areas where metallization is not wanted. UV irradiation is applied uniformly to activate the palladium catalyst and to cure the polymer carrier in areas that are not covered by the mask. Metal is then deposited by electroless plating only or by a combination of electroless and electrolytic plating. This UV-activation technique is particularly useful in additive fine-line patterned metallization. Lastly, computer models for electrolytic and electroless plating processes were developed to provide guidance in plating-process design.

  18. A New Sample Substrate for Imaging and Correlating Organic and Trace Metal Composition in Biological Cells and Tissues

    International Nuclear Information System (INIS)

    Many disease processes involve alterations in the chemical makeup of tissue. Synchrotron-based infrared (IR) and X-ray fluorescence (XRF) microscopes are becoming increasingly popular tools for imaging the organic and trace metal compositions of biological materials, respectively, without the need for extrinsic labels or stains. Fourier transform infrared microspectroscopy (FTIRM) provides chemical information on the organic components of a material at a diffraction-limited spatial resolution of 2-10 μm in the mid-infrared region. The synchrotron X-ray fluorescence (SXRF) microprobe is a complementary technique used to probe trace element content in the same systems with a similar spatial resolution. However to be most beneficial, it is important to combine the results from both imaging techniques on a single sample, which requires precise overlap of the IR and X-ray images. In this work, we have developed a sample substrate containing a gold grid pattern on its surface, which can be imaged with both the IR and X-ray microscopes. The substrate consists of a low trace element glass slide that has a gold grid patterned on its surface, where the major and minor parts of the grid contain 25 and 12 nm gold, respectively. This grid pattern can be imaged with the IR microscope because the reflectivity of gold differs as a function of thickness. The pattern can also be imaged with the SXRF microprobe because the Au fluorescence intensity changes with gold thickness. The tissue sample is placed on top of the patterned substrate. The grid pattern's IR reflectivity image and the gold SXRF image are used as fiducial markers for spatially overlapping the IR and SXRF images from the tissue. Results show that IR and X-ray images can be correlated precisely, with a spatial resolution of less than one pixel (i.e., 2-3 microns). The development of this new tool will be presented along with applications to paraffin-embedded metalloprotein crystals, Alzheimer's disease, and hair

  19. Effect of dual buffer layer structure on the epitaxial growth of AlN on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, D.G., E-mail: dgzhao@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, D.S.; Wu, L.L.; Le, L.C.; Li, L.; Chen, P.; Liu, Z.S. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhu, J.J.; Wang, H.; Zhang, S.M. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China); Yang, H. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer A dual AlN buffer layer structure is proposed to grow AlN films. Black-Right-Pointing-Pointer AlN films could be improved obviously by using the dual AlN buffer layer. Black-Right-Pointing-Pointer The physical mechanism are discussed. - Abstract: A dual AlN buffer layer structure, including an isolated layer and a nucleation layer, is proposed to improve the growth of AlN films on sapphire substrate by metal organic chemical vapor deposition. This method is aimed to weaken the negative nitridation effect and improve lateral growth condition in the initial growth stage. It is found that suitably increasing the thickness of the nucleation layer is in favor of a better structural quality of the AlN film. An examination of surface morphology by atomic force microscopy suggests that the thicker the dual AlN buffer layer, the rougher the surface, and a higher quality of AlN epilayer is resulted.

  20. Effect of dual buffer layer structure on the epitaxial growth of AlN on sapphire

    International Nuclear Information System (INIS)

    Highlights: ► A dual AlN buffer layer structure is proposed to grow AlN films. ► AlN films could be improved obviously by using the dual AlN buffer layer. ► The physical mechanism are discussed. - Abstract: A dual AlN buffer layer structure, including an isolated layer and a nucleation layer, is proposed to improve the growth of AlN films on sapphire substrate by metal organic chemical vapor deposition. This method is aimed to weaken the negative nitridation effect and improve lateral growth condition in the initial growth stage. It is found that suitably increasing the thickness of the nucleation layer is in favor of a better structural quality of the AlN film. An examination of surface morphology by atomic force microscopy suggests that the thicker the dual AlN buffer layer, the rougher the surface, and a higher quality of AlN epilayer is resulted.

  1. Controllability of self-aligned four-terminal planar embedded metal double-gate low-temperature polycrystalline-silicon thin-film transistors on a glass substrate

    Science.gov (United States)

    Ohsawa, Hiroki; Sasaki, Shun; Hara, Akito

    2016-03-01

    Self-aligned four-terminal n-channel (n-ch) and p-channel (p-ch) planar embedded metal double-gate polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) were fabricated on a glass substrate at a low temperature of 550 °C. This device includes a metal top gate (TG) and a metal bottom gate (BG), which are used as the drive and control gates or vice versa. The BG was embedded in a glass substrate, and a poly-Si channel with large lateral grains was fabricated by continuous-wave laser lateral crystallization. The threshold voltage modulation factors under various control gate voltages (γ = ΔVth/ΔVCG) were nearly equal to the theoretical predictions in both the n- and p-ch TFTs. By exploiting this high controllability, an enhancement depletion (ED) inverter was fabricated, and successful operation at 2.0 V was confirmed.

  2. Electrosynthesis of hydrogel films on metal substrates for the development of coatings with tunable drug delivery performances.

    Science.gov (United States)

    De Giglio, E; Cometa, S; Satriano, C; Sabbatini, L; Zambonin, P G

    2009-03-15

    Novel polyacrylates-based hydrogel thin films were prepared by electrochemical polymerization, a new method to obtain hydrogels directly onto metal substrates. 2-Hydroxy-ethyl-methacrylate (HEMA), a macromer poly (ethylene-glycol diacrylate) (PEGDA) and PEGDA copolymerized with acrylic acid (AA) were used to obtain hydrogels. The electrosynthesized coatings were characterized by X-ray photoelectron spectroscopy, to assess their surface chemical composition, and by water content determination measurements, to characterize the swelling behavior. In particular, quartz crystal microbalance with dissipation monitoring was used to evaluate the pH-dependency of the swelling for AA-containing hydrogels. Moreover, a model protein (bovine serum albumin) and a model drug (caffeine) were entrapped within the hydrogel coatings during electrosynthesis, to examine the release performances and mechanisms of the electrosynthesized hydrogels. It was observed that all the examined polymers showed significant release properties and, in particular, AA-containing hydrogel films confirmed a strong pH-dependence as expected. These coatings seem to be promising in orthopedic field for in situ drug delivery applications. PMID:18404708

  3. Optoelectronic properties of eutectic-metal-bonded (EMB) GaAs-AlGaAs structures on Si substrates

    Science.gov (United States)

    Venkatasubramanian, R.; Timmons, M. L.

    1994-11-01

    Device-quality GaAsAlGaAs thin-film hetero-structures have been obtained on Si substrates using a novel approach called eutectic-metal-bonding (EMB). The optoelectronic material properties of the thin-films have been evaluated by a variety of techniques including, Raman spectroscopy, room temperature photoluminescence (PL), and cathodoluminescence (CL) imaging. Transient PL measurement indicates that the minority-carrier lifetime in an EMB GaAs-on-Si thin-film is about 40 times higher than that in state-of-the-art hetero-epitaxial GaAs-on-Si layer. The PL characteristics of the EMB GaAs-on-Si structures have been used to obtain the long-wavelength dispersion values for GaAs thin-film structures. The minority carrier device quality of these thin-films have been evaluated using dark log I- V measurements on n+- p GaAs diodes, spectral-response characterization and solar cell performance data.

  4. Metal oxide nanostructures synthesized on flexible and solid substrates and used for catalysts, UV detectors, and chemical sensors

    Science.gov (United States)

    Willander, Magnus; Sadollahkhani, Azar; Echresh, Ahmad; Nur, Omer

    2014-03-01

    In this paper we demonstrate the visibility of the low temperature chemical synthesis for developing device quality material grown on flexible and solid substrates. Both colorimetric sensors and UV photodetectors will be presented. The colorimetric sensors developed on paper were demonstrated for heavy metal detection, in particular for detecting copper ions in aqueous solutions. The demonstrated colorimetric copper ion sensors developed here are based on ZnO@ZnS core-shell nanoparticles (CSNPs). These sensors demonstrated an excellent low detection limit of less than 1 ppm of copper ions. Further the colorimetric sensors operate efficiently in a wide pH range between 4 and 11, and even in turbulent water. The CSNPs were additionally used as efficient photocatalytic degradation element and were found to be more efficient than pure ZnO nanoparticles (NPs). Also p-NiO/n-ZnO thin film/nanorods pn junctions were synthesized by a two-step synthesis process and were found to act as efficient UV photodetectors. Additionally we show the effect of the morphology of different CuO nanostructures on the efficiency of photo catalytic degradation of Congo red organic dye.

  5. InAs/GaSb core-shell nanowires grown on Si substrates by metal-organic chemical vapor deposition.

    Science.gov (United States)

    Ji, Xianghai; Yang, Xiaoguang; Du, Wenna; Pan, Huayong; Luo, Shuai; Ji, Haiming; Xu, H Q; Yang, Tao

    2016-07-01

    We report the growth of InAs/GaSb core-shell heterostructure nanowires with smooth sidewalls on Si substrates using metal-organic chemical vapor deposition with no assistance from foreign catalysts. Sb adatoms were observed to strongly influence the morphology of the GaSb shell. In particular, Ga droplets form on the nanowire tips when a relatively low TMSb flow rate is used, whereas the droplets are missing and the radial growth of the GaSb is enhanced due to a reduction in the diffusion length of the Ga adatoms when the TMSb flow rate is increased. Moreover, transmission electron microscopy measurements revealed that the GaSb shell coherently grew on the InAs core. The results obtained here show that the InAs/GaSb core-shell nanowires grown using the Si platform have strong potential in the fabrication of future nanometer-scale devices and in the study of fundamental quantum physics. PMID:27232079

  6. Phase transitions in [001]-oriented morphotropic PbZr0.52Ti0.48O3 thin film deposited onto SrTiO3-buffered Si substrate

    International Nuclear Information System (INIS)

    An 85 nm-thick morphotropic PbZr0.52Ti0.48O3 (PZT) film grown epitaxially and [001]-oriented onto a SrTiO3-buffered Si-wafer is investigated using temperature dependent X-ray diffraction. Two phase transitions, at Trt ∼ 500 K and Tc ∼ 685 K, are evidenced and are attributed to structural phase transitions from monoclinic-like to tetragonal-like phase and from tetragonal to paraelectric phase, respectively. The stronger upper shift of Trt value with respect to the bulk one and the weakly affected Tc (Tc bulk ∼ 665 K) are explained assuming misfit strain changes when crossing Trt. This finding opens new perspectives for piezoelectric PZT films in harsh applications.

  7. Preparation of superconducting YBa2Cu3O7-xfilms on metallic substrates by pulsed-laser deposition

    Science.gov (United States)

    Wang, You-qing; Su, Biao; Huang, Xintang; Wang, Qiulang; An, Chengwu; Fan, Yongchang; Lu, Dongsheng

    1998-08-01

    The YBa2Cu3O7-x (YBCO) superconducting thin films with Tc(R equals 0) of 84 K and Jc of 2 X 103 A/cm2 at 77 K, on polycrystalline Ni-based alloys with buffer layers of Yttria-Stabilized-Zirconia (YSZ), have been prepared in situ by excimer laser. The orientation of laser-deposited YSZ buffer layers on NiCr alloys can be improved by choosing the suitable preparing parameters. The microstructure of YBCO thin films, investigated with a scanning tunneling microscopy, shows that the spiral growth structure may be an important characteristic of the high quality YBCO superconducting thin films.

  8. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V.; Goddard, William A., III

    2016-04-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems.

  9. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals.

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V; Goddard, William A

    2016-04-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems. PMID:27001855

  10. Ion-beam-assisted deposition of biaxially aligned yttria-stabilized zirconia template films on metallic substrates for YBCO-coated conductors

    Science.gov (United States)

    Ma, B.; Li, M.; Fisher, B. L.; Balachandran, U.

    2002-07-01

    Biaxially textured yttria-stabilized zirconia (YSZ) films were grown on mechanically polished Hastelloy C276 (HC) substrates by ion-beam-assisted deposition and electron-beam evaporation. The surface root-mean-square (RMS) roughness of the polished HC substrates was ≈3 nm, as measured by atomic force microscopy (AFM). A water-cooled sample stage was used to hold the substrate temperature below 100 °C during deposition. RMS roughness of ≈3.3 nm was measured on the deposited YSZ films by AFM. X-ray pole figures were conducted for texture analysis; in-plane texture measured from YSZ (111) φ-scan FWHM was 13.2° and out-of-plane texture from the YSZ (002) ω-scan FWHM was 7.7°. An ≈10 nm thick CeO2 buffer layer was deposited on the YSZ film at 800 °C before YBCO films were ablated by pulsed laser deposition at 780 °C in a 250 mTorr flowing oxygen environment. Good in-plane texture with FWHM ≈ 7° was observed in YBCO films. Tc = 90 K, with sharp transition, and transport Jc of ≈2.2 × 106 A cm-2 were observed in a 0.5 μm thick, 5 mm wide, and 1 cm long sample at 77 K in self-field.

  11. Ion-beam-assisted deposition of biaxially aligned yttria-stabilized zirconia template films on metallic substrates for YBCO-coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Ma, B. [Energy Technology Division, Argonne National Laboratory, Argonne, IL (United States)]. E-mail: bma@anl.gov; Li, M.; Fisher, B.L.; Balachandran, U. [Energy Technology Division, Argonne National Laboratory, Argonne, IL (United States)

    2002-07-01

    Biaxially textured yttria-stabilized zirconia (YSZ) films were grown on mechanically polished Hastelloy C276 (HC) substrates by ion-beam-assisted deposition and electron-beam evaporation. The surface root-mean-square (RMS) roughness of the polished HC substrates was {approx}3 nm, as measured by atomic force microscopy (AFM). A water-cooled sample stage was used to hold the substrate temperature below 100 deg. C during deposition. RMS roughness of {approx}3.3 nm was measured on the deposited YSZ films by AFM. X-ray pole figures were conducted for texture analysis; in-plane texture measured from YSZ (111) {phi}-scan FWHM was 13.2 deg. and out-of-plane texture from the YSZ (002) {omega}-scan FWHM was 7.7 deg. An {approx}10 nm thick CeO{sub 2} buffer layer was deposited on the YSZ film at 800 deg. C before YBCO films were ablated by pulsed laser deposition at 780 deg. C in a 250 mTorr flowing oxygen environment. Good in-plane texture with FWHM {approx}7 deg. was observed in YBCO films. T{sub c} 90 K, with sharp transition, and transport J{sub c} of {approx}2.2x10{sup 6} A cm{sup -2} were observed in a 0.5 {mu}m thick, 5 mm wide, and 1 cm long sample at 77 K in self-field. (author)

  12. Ion-beam-assisted deposition of biaxially aligned yttria-stabilized zirconia template films on metallic substrates for YBCO-coated conductors

    International Nuclear Information System (INIS)

    Biaxially textured yttria-stabilized zirconia (YSZ) films were grown on mechanically polished Hastelloy C276 (HC) substrates by ion-beam-assisted deposition and electron-beam evaporation. The surface root-mean-square (RMS) roughness of the polished HC substrates was ∼3 nm, as measured by atomic force microscopy (AFM). A water-cooled sample stage was used to hold the substrate temperature below 100 deg. C during deposition. RMS roughness of ∼3.3 nm was measured on the deposited YSZ films by AFM. X-ray pole figures were conducted for texture analysis; in-plane texture measured from YSZ (111) φ-scan FWHM was 13.2 deg. and out-of-plane texture from the YSZ (002) ω-scan FWHM was 7.7 deg. An ∼10 nm thick CeO2 buffer layer was deposited on the YSZ film at 800 deg. C before YBCO films were ablated by pulsed laser deposition at 780 deg. C in a 250 mTorr flowing oxygen environment. Good in-plane texture with FWHM ∼7 deg. was observed in YBCO films. Tc 90 K, with sharp transition, and transport Jc of ∼2.2x106 A cm-2 were observed in a 0.5 μm thick, 5 mm wide, and 1 cm long sample at 77 K in self-field. (author)

  13. GaN Micromechanical Resonators with Meshed Metal Bottom Electrode

    OpenAIRE

    Azadeh Ansari; Che-Yu Liu; Chien-Chung Lin; Hao-Chung Kuo; Pei-Cheng Ku; Mina Rais-Zadeh

    2015-01-01

    This work describes a novel architecture to realize high-performance gallium nitride (GaN) bulk acoustic wave (BAW) resonators. The method is based on the growth of a thick GaN layer on a metal electrode grid. The fabrication process starts with the growth of a thin GaN buffer layer on a Si (111) substrate. The GaN buffer layer is patterned and trenches are made and refilled with sputtered tungsten (W)/silicon dioxide (SiO2) forming passivated metal electrode grids. GaN is then regrown, nucle...

  14. Oxidations of Organic and Inorganic Substrates by Superoxo-, hydroperoxo-, and oxo-compounds of the transition metals.

    Energy Technology Data Exchange (ETDEWEB)

    Michael John Vasbinder

    2006-12-12

    Hammett correlation. It was found that the values of the Hammett reaction constant PN were -1.0(1) for 4-nitro-2-methylpyridine-N-oxide and -2.6(4) for 4-methylpyridine-N-oxide as substrates. The negative value confirms pyridine is acting as a nucleophile. Nucleophiles other than pyridine derivatives were also tested. In the end, it was found that the most effective nucleophiles were the pyridine-N-oxides themselves, meaning that a second equivalent of substrate serves as the most efficient promoter of this oxygen-atom transfer reaction. This relative nucleophilicity of pyridines and pyridine-N-oxides is similar to what is observed in other OAT reactions generating high-valent metal-oxo species.

  15. Oxidations of Organic and Inorganic Substrates by Superoxo-, hydroperoxo-, and oxo-compounds of the transition metals

    International Nuclear Information System (INIS)

    reaction constant PN were -1.0(1) for 4-nitro-2-methylpyridine-N-oxide and -2.6(4) for 4-methylpyridine-N-oxide as substrates. The negative value confirms pyridine is acting as a nucleophile. Nucleophiles other than pyridine derivatives were also tested. In the end, it was found that the most effective nucleophiles were the pyridine-N-oxides themselves, meaning that a second equivalent of substrate serves as the most efficient promoter of this oxygen-atom transfer reaction. This relative nucleophilicity of pyridines and pyridine-N-oxides is similar to what is observed in other OAT reactions generating high-valent metal-oxo species

  16. Dependence of the heavy-metal uptake of higher fungi on substrate composition and site factors. Abhaengigkeit der Schwermetallaufnahme hoeherer Pilze von der Substratzusammensetzung und von Standortsfaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Dietl, G.

    1987-01-01

    The first part of the work investigates the effect of Cd (in the form of the nitrate) on self-cultured champignons (Agaricus bisporus) as regards mycelium growth and fruit development as well as influences on the toxic effect from various substrate additives. The experiments show A. bisporus to be a suitable species for producing standard materials for different heavy-metal concentrations and combinations. In the second part, the heavy-metal content in four different species, Mycena pura s.str., M. rosea, M. pelianthina and M. diosma from different sites (needle and leaf-wood) is established. According to the conclusion drawn, these mushrooms, because of their heavy-metal-accumulating properties, are definitely suited as biological indicators of heavy metal in soil. (MG) With 14 figs., 37 tabs.

  17. Efficiency enhancement of organic light-emitting diodes with an oxygen-plasma-treated ITO substrate and an electron-injection layer of alkali-metal carbonates

    International Nuclear Information System (INIS)

    The efficiency enhancement of organic light-emitting diodes with an oxygen-plasma-treated substrate and an electron-injection layer of alkali-metal carbonates (Li2CO3 and Cs2CO3) was studied. The Li2CO3 and the Cs2CO3 carbonates were thermally evaporated to a thickness of 1 nm. For the device with a Li2CO3 layer, the luminance at 9.25 V of the device with the plasma-treated ITO substrate was found to be improved by approximately 10% compared to that of the device with the plasma-untreated ITO substrate, and the maximum luminance driving voltage was lowered by 1.0 V. For the device with a Cs2CO3 layer, the luminance at 11.25 V of the device with the oxygen plasma-treated ITO substrate was found to be improved by approximately 42.3% compared to that of the device with plasma-untreated ITO substrate, and the maximum luminance driving voltage was lowered by 1.25 V. Especially, the luminous efficiencies of the devices with the Li2CO3 and the Cs2CO3 layers were confirmed to have been increased by 50.0% and 78.1%, respectively, when the oxygen-plasma-treated ITO substrate was used.

  18. Effects of substrate temperature on the unusual non-Fermi liquid metal to insulator transition in perovskite SrIrO3 thin films

    International Nuclear Information System (INIS)

    Electronic transport has been investigated for strong spin-orbit coupled perovskite SrIrO3 thin films grown at various substrate temperatures. The electronic transport of the SrIrO3 films is found to be very sensitive to the growth parameters; in particular, the film can either be a metal or an insulator depending upon the substrate growth temperature. While all the metallic films show unusual sublinear temperature dependent non-Fermi liquid behaviors in resistivity, the insulating film grown at a higher temperature stands out for its inhomogeneous Ir distribution, as analyzed by secondary ion mass spectrometry. This observation demonstrates that the inhomogeneous distribution of cations can be one of the fundamental factors in affecting the electronic transport in heavy element based oxide films and heterostructures. (paper)

  19. Substrate-induced microstructure effects on the dynamics of the photo-induced Metal-insulator transition in VO$_2$ thin films

    CERN Document Server

    Radue, E; Kittiwatanakul, S; Lu, J; Wolf, S A; Rossi, E; Lukaszew, R A; Novikova, I

    2014-01-01

    We investigate the differences in the dynamics of the ultrafast photo-induced metal-insulator transition (MIT) of two VO$_2$ thin films deposited on different substrates, TiO$_2$ and Al$_2$O$_3$, and in particular the temperature dependence of the threshold laser fluence values required to induce various MIT stages in a wide range of sample temperatures (150 K - 320 K). We identified that, although the general pattern of MIT evolution was similar for the two samples, there were several differences. Most notably, the threshold values of laser fluence required to reach the transition to a fully metallic phase in the VO$_2$ film on the TiO$_2$ substrate were nearly constant in the range of temperatures considered, whereas the VO$_2$/Al$_2$O$_3$ sample showed clear temperature dependence. Our analysis qualitatively connects such behavior to the structural differences in the two VO$_2$ films.

  20. Synthesis of Gold Nanoparticles with Buffer-Dependent Variations of Size and Morphology in Biological Buffers

    Science.gov (United States)

    Ahmed, Syed Rahin; Oh, Sangjin; Baba, Rina; Zhou, Hongjian; Hwang, Sungu; Lee, Jaebeom; Park, Enoch Y.

    2016-02-01

    The demand for biologically compatible and stable noble metal nanoparticles (NPs) has increased in recent years due to their inert nature and unique optical properties. In this article, we present 11 different synthetic methods for obtaining gold nanoparticles (Au NPs) through the use of common biological buffers. The results demonstrate that the sizes, shapes, and monodispersity of the NPs could be varied depending on the type of buffer used, as these buffers acted as both a reducing agent and a stabilizer in each synthesis. Theoretical simulations and electrochemical experiments were performed to understand the buffer-dependent variations of size and morphology exhibited by these Au NPs, which revealed that surface interactions and the electrostatic energy on the (111) surface of Au were the determining factors. The long-term stability of the synthesized NPs in buffer solution was also investigated. Most NPs synthesized using buffers showed a uniquely wide range of pH stability and excellent cell viability without the need for further modifications.

  1. Synthesis of Gold Nanoparticles with Buffer-Dependent Variations of Size and Morphology in Biological Buffers.

    Science.gov (United States)

    Ahmed, Syed Rahin; Oh, Sangjin; Baba, Rina; Zhou, Hongjian; Hwang, Sungu; Lee, Jaebeom; Park, Enoch Y

    2016-12-01

    The demand for biologically compatible and stable noble metal nanoparticles (NPs) has increased in recent years due to their inert nature and unique optical properties. In this article, we present 11 different synthetic methods for obtaining gold nanoparticles (Au NPs) through the use of common biological buffers. The results demonstrate that the sizes, shapes, and monodispersity of the NPs could be varied depending on the type of buffer used, as these buffers acted as both a reducing agent and a stabilizer in each synthesis. Theoretical simulations and electrochemical experiments were performed to understand the buffer-dependent variations of size and morphology exhibited by these Au NPs, which revealed that surface interactions and the electrostatic energy on the (111) surface of Au were the determining factors. The long-term stability of the synthesized NPs in buffer solution was also investigated. Most NPs synthesized using buffers showed a uniquely wide range of pH stability and excellent cell viability without the need for further modifications. PMID:26847691

  2. Epitaxial growth and multiferroic properties of cation-engineered (Bi{sub 0.45}La{sub 0.05}Ba{sub 0.5})(Fe{sub 0.75}Nb{sub 0.25})O{sub 3} thin film on Ir-buffered (0 0 1) MgO substrate

    Energy Technology Data Exchange (ETDEWEB)

    Paik, Hanjong [Department of Materials Science and Engineering, Cornell University, Ithaca NY 14853 (United States); Kim, Hyun-Suk [Department of Materials Engineering, Chungnam University, Daejeon 305-764 (Korea, Republic of); Hong, Jongin, E-mail: hongj@cau.ac.kr [Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756 (Korea, Republic of)

    2015-04-15

    Highlights: • Epitaxial (Bi{sub 0.45}La{sub 0.05}Ba{sub 0.5})(Fe{sub 0.75}Nb{sub 0.25})O{sub 3} thin film was grown on the Ir-buffered (0 0 1) MgO substrate by pulsed laser deposition. • Its ferroelectric polarization switching was investigated by piezoresponse force microscopy. • Its ferromagnetic hysteresis at room temperature and ferrimagnetic–ferromagnetic transition at low temperature were evaluated. • Artificial A- and B-site cation engineering would result in stable multiferroic properties at room temperature. - Abstract: An epitaxial (Bi{sub 0.45}La{sub 0.05}Ba{sub 0.5})(Fe{sub 0.75}Nb{sub 0.25})O{sub 3} (BLB-FNO) thin film was successfully grown on an Ir-buffered (0 0 1) MgO substrate by pulsed laser deposition (PLD). The “cube-on-cube” epitaxial relation, (0 0 1)[1 0 0] BLB-FNO//(0 0 1)[1 0 0] Ir//(0 0 1)[1 0 0] MgO, was confirmed by X-ray diffraction (XRD) pole figures and cross-sectional high-resolution transmission electron microscopy (HRTEM). The ferroelectric polarization switching of the BLB-FNO thin film was investigated by piezoresponse force microscopy (PFM). Its magnetic properties, such as ferromagnetic hysteresis at room temperature and possible magnetic transition at low temperature, were also evaluated. Accordingly, we successfully demonstrated that artificial A- and B-site cation engineering would allow for stable multiferroic properties at room temperature.

  3. Evaluation of the Accumulation of Trace Metals (as, U, CR, CU, PB, Zn) on Iron-Manganese Coatings on in Situ Stream Pebbles and Emplaced Substrates

    Science.gov (United States)

    Turpin, M. M.; Blake, J.; Crossey, L. J.; Ali, A.; Hansson, L.

    2015-12-01

    Exposure to trace metals (As, U, Cr, Cu, Pb, Zn) has potential negative health effects on human populations and wildlife. Geothermal waters often have elevated concentrations of trace elements and understanding the geochemical cycling of these elements can be challenging. Previous studies have utilized in situ stream pebbles and glass or ceramic substrates with iron-manganese oxide coatings to understand contamination and or chemical cycling. This project's main focus is to develop an ideal tracing method using adsorption onto substrate surfaces and to define key parameters that are necessary for the phenomenon of adsorption between trace metals and these surface coatings to occur. Sampling locations include the Jemez River and Rio San Antonio in the Jemez mountains, northern New Mexico. Both streams have significant geothermal inputs. Pebbles and cobbles were gathered from the active stream channel and 6mm glass beads and 2 X1 in. ceramic plates were placed in streams for three weeks to allow for coating accumulation. Factors such as leachate type, water pH, substrate type, coating accumulation period and leach time were all considered in this experiment. It was found that of the three leachates (aqua regia, 10% aqua regia and hydroxylamine), hydroxylamine was the most effective at leaching coatings without dissolving substrates. Samples leached with aqua regia and 10% aqua regia were found to lose weight and mass over the following 5, 7, and 10 day measurements. Glass beads were determined to be more effective than in stream pebbles as an accumulation substrate: coatings were more easily controlled and monitored. Samples leached with hydroxylamine for 5 hours and 72 hours showed little difference in their leachate concentrations, suggesting that leach time has little impact on the concentration of leachate samples. This research aims to find the best method for trace metal accumulation in streams to aid in understanding geochemical cycling.

  4. Buffer layers for superconducting Y-Ba-Cu-O thin films on silicon and SiO sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Reus, R. de; Saris, F.W. (FOM-Institute for Atomic and Molecular Physics, Amsterdam (Netherlands)); Kolk, G.J. van der; Witmer, C.; Dam, B. (Philips Research Labs., Eindhoven (Netherlands)); Blank, D.H.A.; Adelerhof, D.J.; Flokstra, J. (Twente Univ., Enschede (Netherlands))

    1990-09-01

    By direct deposition onto hot substrates, using laser ablation, crystalline YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (123) was obtained at 650deg C on SiO{sub 2}, but not on (100) Si substrates. The 123 film did not show a superconducting transition due to interfacial reactions. The failure temperature of insulating buffer layers, such as tantalum oxide and hafnium oxide, is around 500deg C. Although MgO and BaZrO{sub 3} show a high stability in contact with 123 at 900deg C, they fail as a diffusion barrier at much lower temperatures. Below 400deg C barium diffuses through MgO, which itself remains unaffected. Using BaZrO{sub 3} the same happens around 700deg C. BaF{sub 2} fails as a diffusion barrier below 400deg C. Using laser ablation, high quality 123 films were grown on ZrO{sub 2} buffer layers above 650deg C. For the first time we report superconducting transitions of 123 deposited at 650deg C onto an amorphous metal alloy, Ir{sub 45}Ta{sub 55}. The problems encountered using conducting buffer layers are either a low reaction temperature with 123 (HfB{sub 2} and HfN) or oxidation of the metal alloy (Ir{sub 45}Ta{sub 55}) around 400deg C. Intermediate noble metal layers silver and Ag/Au/Ag could not prevent oxygen diffusion towards the underlying buffer layer. (orig.).

  5. Deposition of Metal-Organic Frameworks by Liquid-Phase Epitaxy: The Influence of Substrate Functional Group Density on Film Orientation

    OpenAIRE

    Christof Wöll; Andreas Terfort; Björn Schüpbach; Bo Liu; Arslan, Hasan K.; Xia Stammer; Osama Shekhah; Jinxuan Liu

    2012-01-01

    The liquid phase epitaxy (LPE) of the metal-organic framework (MOF) HKUST-1 has been studied for three different COOH-terminated templating organic surfaces prepared by the adsorption of self-assembled monolayers (SAMs) on gold substrates. Three different SAMs were used, mercaptohexadecanoic acid (MHDA), 4’-carboxyterphenyl-4-methanethiol (TPMTA) and 9-carboxy-10-(mercaptomethyl)triptycene (CMMT). The XRD data demonstrate that highly oriented HKUST-1 SURMOFs with an orientation along the (100...

  6. Pulsed-laser crystallization and epitaxial growth of metal-organic films of Ca-doped LaMnO{sub 3} on STO and LSAT substrates

    Energy Technology Data Exchange (ETDEWEB)

    Daoudi, K. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, 305-8565 Tsukuba (Japan)]. E-mail: kais.daoudi@gmail.com; Tsuchiya, T. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, 305-8565 Tsukuba (Japan); Kumagai, T. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, 305-8565 Tsukuba (Japan)

    2007-05-30

    Ca-doped LaMnO{sub 3} (LCMO) thin films have been successfully prepared on SrTiO{sub 3} (STO) and [(LaAlO{sub 3}){sub 0.3}-(SrAlTaO{sub 6}){sub 0.7}] (LSAT) substrates using the excimer laser assisted metal-organic deposition (ELAMOD) process. The crystallization and the epitaxial growth of the amorphous metal-organic LCMO thin films have been achieved using a KrF excimer laser irradiation while the substrates were kept at constant temperature of 500 deg. C. Epitaxial films were obtained using laser fluence in the interval of 50-120 mJ/cm{sup 2}. The microstructure of the LCMO films was studied using cross-section transmission electron microscopy. High quality of LCMO films having smooth surfaces and sharp interfaces were obtained on both the STO and the LSAT substrates. The effect of the laser fluence on the temperature coefficient of resistance (TCR) was investigated. The largest values of TCR of the LCMO grown on the LSAT and the STO substrates of 8.3% K{sup -1} and 7.46% K{sup -1} were obtained at different laser fluence of 80 mJ/cm{sup 2} and 70 mJ/cm{sup 2}, respectively.

  7. Influence of metal-support interaction on the surface structure of gold nanoclusters deposited on native SiO(x)/Si substrates.

    Science.gov (United States)

    Portale, Giuseppe; Sciortino, Luisa; Albonetti, Cristiano; Giannici, Francesco; Martorana, Antonino; Bras, Wim; Biscarini, Fabio; Longo, Alessandro

    2014-04-14

    The structure of small gold nanoclusters (around 2.5 nm) deposited on different silica-on-silicon (SiOx/Si) substrates is investigated using several characterization techniques (AFM, XRD, EXAFS and GISAXS). The grain morphology and the surface roughness of the deposited gold cluster layers are determined by AFM. The in-plane GISAXS intensity is modelled in order to obtain information about the cluster size and the characteristic length scale of the surface roughness. The surface morphology of the deposited clusters depends on whether the native defect-rich (n-SiOx/Si) or the defect-poor substrate obtained by thermal treatment (t-SiO2/Si) is used. Gold clusters show a stronger tendency to aggregate when deposited on n-SiOx/Si, resulting in films characterized by a larger grain dimension (around 20 nm) and by a higher surface roughness (up to 5 nm). The more noticeable cluster aggregation on n-SiOx/Si substrates is explained in terms of metal-support interaction mediated by the defects located on the surface of the native silica substrate. Evidence of metal-support interaction is provided by EXAFS, demonstrating the existence of an Au-O distance for clusters deposited on n-SiOx/Si that is not found on t-SiO2/Si. PMID:24576989

  8. Aggregation and adhesion of gold nanoparticles in phosphate buffered saline

    International Nuclear Information System (INIS)

    In applications in medicine and more specifically drug delivery, the dispersion stability of nanoparticles plays a significant role on their final performances. In this study, with the use of two laser technologies, dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA), we report a simple method to estimate the stability of nanoparticles dispersed in phosphate buffered saline (PBS). Stability has two features: (1) self-aggregation as the particles tend to stick to each other; (2) disappearance of particles as they adhere to surrounding substrate surfaces such as glass, metal, or polymer. By investigating the effects of sonication treatment and surface modification by five types of surfactants, including nonylphenol ethoxylate (NP9), polyvinyl pyrrolidone (PVP), human serum albumin (HSA), sodium dodecyl sulfate (SDS) and citrate ions on the dispersion stability, the varying self-aggregation and adhesion of gold nanoparticles dispersed in PBS are demonstrated. The results showed that PVP effectively prevented aggregation, while HSA exhibited the best performance in avoiding the adhesion of gold nanoparticle in PBS onto glass and metal. The simple principle of this method makes it a high potential to be applied to other nanoparticles, including virus particles, used in dispersing and processing.

  9. Aggregation and adhesion of gold nanoparticles in phosphate buffered saline

    Energy Technology Data Exchange (ETDEWEB)

    Du Shangfeng, E-mail: s.du@bham.ac.uk; Kendall, Kevin; Toloueinia, Panteha; Mehrabadi, Yasamin; Gupta, Gaurav; Newton, Jill [University of Birmingham, School of Chemical Engineering (United Kingdom)

    2012-03-15

    In applications in medicine and more specifically drug delivery, the dispersion stability of nanoparticles plays a significant role on their final performances. In this study, with the use of two laser technologies, dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA), we report a simple method to estimate the stability of nanoparticles dispersed in phosphate buffered saline (PBS). Stability has two features: (1) self-aggregation as the particles tend to stick to each other; (2) disappearance of particles as they adhere to surrounding substrate surfaces such as glass, metal, or polymer. By investigating the effects of sonication treatment and surface modification by five types of surfactants, including nonylphenol ethoxylate (NP9), polyvinyl pyrrolidone (PVP), human serum albumin (HSA), sodium dodecyl sulfate (SDS) and citrate ions on the dispersion stability, the varying self-aggregation and adhesion of gold nanoparticles dispersed in PBS are demonstrated. The results showed that PVP effectively prevented aggregation, while HSA exhibited the best performance in avoiding the adhesion of gold nanoparticle in PBS onto glass and metal. The simple principle of this method makes it a high potential to be applied to other nanoparticles, including virus particles, used in dispersing and processing.

  10. Synthesis of Poly-Silicon Thin Films on Glass Substrate Using Laser Initiated Metal Induced Crystallization of Amorphous Silicon for Space Power Application

    Science.gov (United States)

    Abu-Safe, Husam H.; Naseem, Hameed A.; Brown, William D.

    2007-01-01

    Poly-silicon thin films on glass substrates are synthesized using laser initiated metal induced crystallization of hydrogenated amorphous silicon films. These films can be used to fabricate solar cells on low cost glass and flexible substrates. The process starts by depositing 200 nm amorphous silicon films on the glass substrates. Following this, 200 nm of sputtered aluminum films were deposited on top of the silicon layers. The samples are irradiated with an argon ion cw laser beam for annealing. Laser power densities ranging from 4 to 9 W/cm2 were used in the annealing process. Each area on the sample is irradiated for a different exposure time. Optical microscopy was used to examine any cracks in the films and loss of adhesion to the substrates. X-Ray diffraction patterns from the initial results indicated the crystallization in the films. Scanning electron microscopy shows dendritic growth. The composition analysis of the crystallized films was conducted using Energy Dispersive x-ray Spectroscopy. The results of poly-silicon films synthesis on space qualified flexible substrates such as Kapton are also presented.

  11. Growth and characterization of well-aligned densely-packed rutile TiO(2) nanocrystals on sapphire substrates via metal-organic chemical vapor deposition.

    Science.gov (United States)

    Chen, C A; Chen, Y M; Korotcov, A; Huang, Y S; Tsai, D S; Tiong, K K

    2008-02-20

    Well-aligned densely-packed rutile TiO(2) nanocrystals (NCs) have been grown on sapphire (SA) (100) and (012) substrates via metal-organic chemical vapor deposition (MOCVD), using titanium-tetraisopropoxide (TTIP, Ti(OC(3)H(7))(4)) as a source reagent. The surface morphology as well as structural and spectroscopic properties of the as-deposited NCs were characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffractometry (SAED), x-ray diffraction (XRD) and micro-Raman spectroscopy. FESEM micrographs reveal that vertically aligned NCs were grown on SA(100), whereas the NCs on the SA(012) were grown with a tilt angle of ∼33° from the normal to substrates. TEM and SAED measurements showed that the TiO(2) NCs on SA(100) with square cross section have their long axis directed along the [001] direction. The XRD results reveal TiO(2) NCs with either (002) orientation on SA(100) substrate or (101) orientation on SA(012) substrate. A strong substrate effect on the alignment of the growth of TiO(2) NCs has been demonstrated and the probable mechanism for the formation of these NCs has been discussed. PMID:21817648

  12. Growth and characterization of well-aligned densely-packed rutile TiO{sub 2} nanocrystals on sapphire substrates via metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C A; Chen, Y M; Korotcov, A; Huang, Y S [Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Tsai, D S [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Tiong, K K [Department of Electrical Engineering, National Taiwan Ocean University, Keelung 202, Taiwan (China)], E-mail: ysh@mail.ntust.edu.tw

    2008-02-20

    Well-aligned densely-packed rutile TiO{sub 2} nanocrystals (NCs) have been grown on sapphire (SA) (100) and (012) substrates via metal-organic chemical vapor deposition (MOCVD), using titanium-tetraisopropoxide (TTIP, Ti(OC{sub 3}H{sub 7}){sub 4}) as a source reagent. The surface morphology as well as structural and spectroscopic properties of the as-deposited NCs were characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffractometry (SAED), x-ray diffraction (XRD) and micro-Raman spectroscopy. FESEM micrographs reveal that vertically aligned NCs were grown on SA(100), whereas the NCs on the SA(012) were grown with a tilt angle of {approx}33 deg. from the normal to substrates. TEM and SAED measurements showed that the TiO{sub 2} NCs on SA(100) with square cross section have their long axis directed along the [001] direction. The XRD results reveal TiO{sub 2} NCs with either (002) orientation on SA(100) substrate or (101) orientation on SA(012) substrate. A strong substrate effect on the alignment of the growth of TiO{sub 2} NCs has been demonstrated and the probable mechanism for the formation of these NCs has been discussed.

  13. Growth and characterization of well-aligned densely-packed rutile TiO2 nanocrystals on sapphire substrates via metal organic chemical vapor deposition

    Science.gov (United States)

    Chen, C. A.; Chen, Y. M.; Korotcov, A.; Huang, Y. S.; Tsai, D. S.; Tiong, K. K.

    2008-02-01

    Well-aligned densely-packed rutile TiO2 nanocrystals (NCs) have been grown on sapphire (SA) (100) and (012) substrates via metal-organic chemical vapor deposition (MOCVD), using titanium-tetraisopropoxide (TTIP, Ti(OC3H7)4) as a source reagent. The surface morphology as well as structural and spectroscopic properties of the as-deposited NCs were characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffractometry (SAED), x-ray diffraction (XRD) and micro-Raman spectroscopy. FESEM micrographs reveal that vertically aligned NCs were grown on SA(100), whereas the NCs on the SA(012) were grown with a tilt angle of ~33° from the normal to substrates. TEM and SAED measurements showed that the TiO2 NCs on SA(100) with square cross section have their long axis directed along the [001] direction. The XRD results reveal TiO2 NCs with either (002) orientation on SA(100) substrate or (101) orientation on SA(012) substrate. A strong substrate effect on the alignment of the growth of TiO2 NCs has been demonstrated and the probable mechanism for the formation of these NCs has been discussed.

  14. Propagation of misfit dislocations from buffer/Si interface into Si

    Science.gov (United States)

    Liliental-Weber, Zuzanna; Maltez, Rogerio Luis; Morkoc, Hadis; Xie, Jinqiao

    2011-08-30

    Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.

  15. Simulation on near-field light generated by metal nano-dot on GaAs substrate for heat source of heat-assisted magnetic recording

    Science.gov (United States)

    Katayama, Ryuichi

    2014-09-01

    Heat-assisted magnetic recording (HAMR) is promising for achieving more than 1 Tb/inch2 recording density. A near-field transducer (NFT), which forms a hot spot of 10-100 nm in diameter on a recording medium, is necessary in HAMR. In this study, localized surface plasmons generated by a metal nano-dot in a novel device for a heat source of heat-assisted magnetic recording were analyzed using a simple model in which a metal hemisphere was formed on a GaAs substrate and a quasi-electrostatic approximation. The scattering and absorption efficiencies as well as the enhancement factor were investigated for several kinds of metal. As a result, their dependence on the wavelength and the polarization direction of the incident light was clarified.

  16. Structural and electrical properties of 0.7Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3} thin films grown on Ir/MgO buffered Si(100) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Wu, F.; Zhang, X. [Chinese Academy of Sciences, State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Shanghai (China); Graduate School of Chinese Academy of Science, Beijing (China); Li, X.M.; Yu, W.D.; Gao, X.D. [Chinese Academy of Sciences, State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Shanghai (China)

    2007-09-15

    Thin films of 0.7Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3} (PMN-PT) have been grown on Ir/MgO buffered Si(100) substrates at different substrate temperatures by pulsed laser deposition. Crystalline phases as well as preferred orientations in the PMN-PT films were investigated by X-ray diffraction analysis (XRD). The microstructure, dielectric and ferroelectric properties of PMN-PT film prepared at 650 C were studied. The results show that the film prepared at 650 C exhibits pure perovskite phase and single c-axis orientation. The dielectric constant and dissipation factor of the single c-axis oriented film are 1000 and 0.04 at a frequency of 1 kHz, while the remnant polarization and coercive field are about 13.0 {mu}C/cm{sup 2} and 100 kV/cm under an electric field of 480 kV/cm, respectively. (orig.)

  17. Buffer moisture protection system

    International Nuclear Information System (INIS)

    With the present knowledge, bentonite blocks have to be protected from the air relative humidity and from any moisture leakages in the environment that might cause swelling of the bentonite blocks during the 'open' installation phase before backfilling. The purpose of this work was to design the structural reference solution both for the bottom of the deposition hole and for the buffer moisture protection and dewatering system with their integrated equipment needed in the deposition hole. This report describes the Posiva's reference solution for the buffer moisture protection system and the bottom plate on basis of the demands and functional requirements set by long-term safety. The reference solution with structural details has been developed in research work made 2010-2011. The structural solution of the moisture protection system has not yet been tested in practice. On the bottom of the deposition hole a copper plate which protects the lowest bentonite block from the gathered water is installed straight to machined and even rock surface. The moisture protection sheet made of EPDM rubber is attached to the copper plate with an inflatable seal. The upper part of the moisture protection sheet is fixed to the collar structures of the lid which protects the deposition hole in the disposal tunnel. The main function of the moisture protection sheet is to protect bentonite blocks from the leaking water and from the influence of the air humidity at their installation stage. The leaking water is controlled by the dewatering and alarm system which has been integrated into the moisture protection liner. (orig.)

  18. Buffer moisture protection system

    Energy Technology Data Exchange (ETDEWEB)

    Ritola, J.; Peura, J. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2013-11-15

    With the present knowledge, bentonite blocks have to be protected from the air relative humidity and from any moisture leakages in the environment that might cause swelling of the bentonite blocks during the 'open' installation phase before backfilling. The purpose of this work was to design the structural reference solution both for the bottom of the deposition hole and for the buffer moisture protection and dewatering system with their integrated equipment needed in the deposition hole. This report describes the Posiva's reference solution for the buffer moisture protection system and the bottom plate on basis of the demands and functional requirements set by long-term safety. The reference solution with structural details has been developed in research work made 2010-2011. The structural solution of the moisture protection system has not yet been tested in practice. On the bottom of the deposition hole a copper plate which protects the lowest bentonite block from the gathered water is installed straight to machined and even rock surface. The moisture protection sheet made of EPDM rubber is attached to the copper plate with an inflatable seal. The upper part of the moisture protection sheet is fixed to the collar structures of the lid which protects the deposition hole in the disposal tunnel. The main function of the moisture protection sheet is to protect bentonite blocks from the leaking water and from the influence of the air humidity at their installation stage. The leaking water is controlled by the dewatering and alarm system which has been integrated into the moisture protection liner. (orig.)

  19. Photo-induced wettability of TiO{sub 2} film with Au buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Purkayastha, Debarun Dhar; Sangani, L. D. Varma; Krishna, M. Ghanashyam [School of Physics, University of Hyderabad, Hyderabad-500046 (India); Madhurima, V., E-mail: madhurima.v@gmail.com [Department of Physics, Central University of Tamil Nadu, Thiruvarur-610004 (India)

    2014-04-24

    The effect of thickness of Au buffer layer (15-25 nm) between TiO{sub 2} film and substrate on the wettability of TiO{sub 2} films is reported. TiO{sub 2} films grown on Au buffer layer have a higher contact angle of 96-;100° as compared to 47.6o for the film grown without buffer layer. The transition from hydrophobicity to hydrophilicity under UV irradiation occurs within 10 min. for the buffer layered films whereas it is almost 30 min. for the film grown without buffer layer. The enhanced photo induced hydrophilicity is shown to be surface energy driven.

  20. Comparison of corrosion behaviors between SS304 and Ti substrate coated with (Ti,Zr)N thin films as Metal bipolar plate for unitized regenerative fuel cell

    International Nuclear Information System (INIS)

    In this study, a (Ti,Zr)N coating consisting of nano-composite structure of the TiN and ZrN phases is deposited on SS304 and titanium substrates as the metal bipolar plate through the cathodic arc evaporation techniques. This improves the corrosion resistance of SS304 and Ti metal when used in a unitized regenerative fuel cell (URFC). The corrosion behaviors of these two substrates are compared. Scanning electron microscope, energy dispersive spectrometer, and X-ray diffractometer are used to characterize the microstructure, thickness, chemical composition, as well as crystalline and phase states of the deposited thin films. The potentiodynamic polarization of the (Ti,Zr)N coating is tested in a simulated URFC H2 environment, i.e., 0.50 M H2SO4 with 3 ppm NaF solution purging with H2 gas at 60 °C. Experimental results demonstrate that the (Ti,Zr)N coating improves the corrosion resistance of SS304 (about 215 times that of uncoated SS304) better than that of the Ti substrate (about 200 times that of uncoated Ti). The enhanced corrosion resistance is attributed to the nano-composite structure of TiN and ZrN, which has a dense and columnar microstructure that is impermeable to a corrosive medium. The coating of the (Ti,Zr)N layer has better corrosion resistance than the increased sheet resistance for both substrates. Therefore, the (Ti,Zr)N–SS304 and (Ti,Zr)N–Ti samples, specifically the (Ti,Zr)N–SS304 sample, are good candidates as the material for URFC H2 side metal bipolar plate. - Highlights: • A (Ti,Zr)N coating is deposited on SS304 and titanium substrates. • This coating contains a nano-composite structure of TiN and ZrN phases. • Effective improvement of corrosion resistance on substrates has been obtained. • Coating on SS304 has better enhancement of corrosion resistance than that on Ti. • It can be used for bipolar-plate material of the unitized regenerative fuel cell

  1. Structure and energetics of benzene adsorbed on transition-metal surfaces: density-functional theory with van der Waals interactions including collective substrate response

    International Nuclear Information System (INIS)

    The adsorption of benzene on metal surfaces is an important benchmark system for hybrid inorganic/organic interfaces. The reliable determination of the interface geometry and binding energy presents a significant challenge for both theory and experiment. Using the Perdew–Burke–Ernzerhof (PBE), PBE + vdW (van der Waals) and the recently developed PBE + vdWsurf (density-functional theory with vdW interactions that include the collective electronic response of the substrate) methods, we calculated the structures and energetics for benzene on transition-metal surfaces: Cu, Ag, Au, Pd, Pt, Rh and Ir. Our calculations demonstrate that vdW interactions increase the binding energy by more than 0.70 eV for physisorbed systems (Cu, Ag and Au) and by an even larger amount for strongly bound systems (Pd, Pt, Rh and Ir). The collective response of the substrate electrons captured via the vdWsurf method plays a significant role for most substrates, shortening the equilibrium distance by 0.25 Å for Cu and decreasing the binding energy by 0.27 eV for Rh. The reliability of our results is assessed by comparison with calculations using the random-phase approximation including renormalized single excitations, and the experimental data from temperature-programmed desorption, microcalorimetry measurements and low-energy electron diffraction. (paper)

  2. Ceramic barrier layers for flexible thin film solar cells on metallic substrates: a laboratory scale study for process optimization and barrier layer properties.

    Science.gov (United States)

    Delgado-Sanchez, Jose-Maria; Guilera, Nuria; Francesch, Laia; Alba, Maria D; Lopez, Laura; Sanchez, Emilio

    2014-11-12

    Flexible thin film solar cells are an alternative to both utility-scale and building integrated photovoltaic installations. The fabrication of these devices over electrically conducting low-cost foils requires the deposition of dielectric barrier layers to flatten the substrate surface, provide electrical isolation between the substrate and the device, and avoid the diffusion of metal impurities during the relatively high temperatures required to deposit the rest of the solar cell device layers. The typical roughness of low-cost stainless-steel foils is in the hundred-nanometer range, which is comparable or larger than the thin film layers comprising the device and this may result in electrical shunts that decrease solar cell performance. This manuscript assesses the properties of different single-layer and bilayer structures containing ceramics inks formulations based on Al2O3, AlN, or Si3N4 nanoparticles and deposited over stainless-steel foils using a rotogravure printing process. The best control of the substrate roughness was achieved for bilayers of Al2O3 or AlN with mixed particle size, which reduced the roughness and prevented the diffusion of metals impurities but AlN bilayers exhibited as well the best electrical insulation properties. PMID:25296706

  3. Buffer capacity of biologics--from buffer salts to buffering by antibodies.

    Science.gov (United States)

    Karow, Anne R; Bahrenburg, Sven; Garidel, Patrick

    2013-01-01

    Controlling pH is essential for a variety of biopharmaceutical process steps. The chemical stability of biologics such as monoclonal antibodies is pH-dependent and slightly acidic conditions are favorable for stability in a number of cases. Since control of pH is widely provided by added buffer salts, the current study summarizes the buffer characteristics of acetate, citrate, histidine, succinate, and phosphate buffers. Experimentally derived values largely coincide with values calculated from a model that had been proposed in 1922 by van Slyke. As high concentrated protein formulations become more and more prevalent for biologics, the self-buffering potential of proteins becomes of relevance. The current study provides information on buffer characteristics for pH ranges down to 4.0 and up to 8.0 and shows that a monoclonal antibody at 50 mg/mL exhibits similar buffer capacity as 6 mM citrate or 14 mM histidine (pH 5.0-6.0). Buffer capacity of antibody solutions scales linearly with protein concentration up to more than 200 mg/mL. At a protein concentration of 220 mg/mL, the buffer capacity resembles the buffer capacity of 30 mM citrate or 50 mM histidine (pH 5.0-6.0). The buffer capacity of monoclonal antibodies is practically identical at the process relevant temperatures 5, 25, and 40°C. Changes in ionic strength of ΔI=0.15, in contrast, can alter the buffer capacity up to 35%. In conclusion, due to efficient self-buffering by antibodies in the pH range of favored chemical stability, conventional buffer excipients could be dispensable for pH stabilization of high concentrated protein solutions. PMID:23296746

  4. Universal buffers for use in biochemistry and biophysical experiments

    Directory of Open Access Journals (Sweden)

    Dewey Brooke

    2015-08-01

    Full Text Available The use of buffers that mimic biological solutions is a foundation of biochemical and biophysical studies. However, buffering agents have both specific and nonspecific interactions with proteins. Buffer molecules can induce changes in conformational equilibria, dynamic behavior, and catalytic properties merely by their presence in solution. This effect is of concern because many of the standard experiments used to investigate protein structure and function involve changing solution conditions such as pH and/or temperature. In experiments in which pH is varied, it is common practice to switch buffering agents so that the pH is within the working range of the weak acid and conjugate base. If multiple buffers are used, it is not always possible to decouple buffer induced change from pH or temperature induced change. We have developed a series of mixed biological buffers for protein analysis that can be used across a broad pH range, are compatible with biologically relevant metal ions, and avoid complications that may arise from changing the small molecule composition of buffers when pH is used as an experimental variable.

  5. Effect of the substrate on the properties of ZnO-MgO thin films grown by atmospheric pressure metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Huerta, A.M., E-mail: atohuer@hotmail.com [Instituto Politecnico Nacional, Grupo de Ingenieria en Procesamiento de Materiales CICATA-IPN, Unidad Altamira, km 14.5, Carretera Tampico-Puerto Industrial Altamira. C. P. 89600, Altamira, Tamps (Mexico); Dominguez-Crespo, M.A. [Instituto Politecnico Nacional, Grupo de Ingenieria en Procesamiento de Materiales CICATA-IPN, Unidad Altamira, km 14.5, Carretera Tampico-Puerto Industrial Altamira. C. P. 89600, Altamira, Tamps (Mexico); Brachetti-Sibaja, S.B. [Alumna del postgrado en Tecnologia Avanzada del CICATA-IPN, Unidad Altamira IPN, km 14.5, Carretera Tampico-Puerto Industrial Altamira. C. P. 89600, Altamira, Tamps (Mexico); Arenas-Alatorre, J. [Instituto de Fisica, UNAM, Apartado Postal 20-364, 01000, D.F. (Mexico); Rodriguez-Pulido, A. [Unidad Profesional Adolfo Lopez Mateos, Luis Enrique Erro s/n, 07738, D. F. (Mexico)

    2011-07-01

    The ZnO-MgO alloys possess attractive properties for possible applications in optoelectronic and display devices; however, the optical properties are strongly dependent on the deposition parameters. In this work, the effect of the glassy and metallic substrates on the structural, morphological and optical properties of ZnO-MgO thin films using atmospheric pressure metal-organic chemical vapor deposition was investigated at relatively low deposition temperature, 500 deg. C. Magnesium and zinc acetylacetonates were used as the metal-organic source. X-ray diffraction experiments provided evidence that the kind of substrates cause a deviation of c-axis lattice constant due to the constitution of a oxide mixture (ZnO and MgO) in combination with different intermetallic compounds(Mg{sub 2}Zn{sub 11} and Mg{sub 4}Zn{sub 7}) in the growth films. The substitutional and interstitial sites of Mg{sup 2+} instead of Zn{sup 2+} ions in the lattice are the most probable mechanism to form intermetallic compounds. The optical parameters as well as thickness of the films were calculated by Spectroscopic Ellipsometry using the classical dispersion model based on the sum of the single and double Lorentz and Drude oscillators in combination with Kato-Adachi equations, as well as X-ray reflectivity.

  6. Effect of the substrate on the properties of ZnO-MgO thin films grown by atmospheric pressure metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    The ZnO-MgO alloys possess attractive properties for possible applications in optoelectronic and display devices; however, the optical properties are strongly dependent on the deposition parameters. In this work, the effect of the glassy and metallic substrates on the structural, morphological and optical properties of ZnO-MgO thin films using atmospheric pressure metal-organic chemical vapor deposition was investigated at relatively low deposition temperature, 500 deg. C. Magnesium and zinc acetylacetonates were used as the metal-organic source. X-ray diffraction experiments provided evidence that the kind of substrates cause a deviation of c-axis lattice constant due to the constitution of a oxide mixture (ZnO and MgO) in combination with different intermetallic compounds(Mg2Zn11 and Mg4Zn7) in the growth films. The substitutional and interstitial sites of Mg2+ instead of Zn2+ ions in the lattice are the most probable mechanism to form intermetallic compounds. The optical parameters as well as thickness of the films were calculated by Spectroscopic Ellipsometry using the classical dispersion model based on the sum of the single and double Lorentz and Drude oscillators in combination with Kato-Adachi equations, as well as X-ray reflectivity.

  7. Structural properties and metallic conductivity of Ti1-x Nb x O2 films grown by atomic layer deposition on crystalline substrates

    Science.gov (United States)

    Luka, Grzegorz; Wachnicki, Lukasz; Jakiela, Rafal; Lusakowska, Elzbieta

    2015-12-01

    Niobium-doped titanium dioxide (Ti1-x Nb x O2, x  ≈  0.04, TNO) films were grown by atomic layer deposition (ALD) at a low growth temperature (220 °C) on LaAlO3(1 0 0) (LAO) and Al2O3(0 0 0 1) (c-sapphire) substrates. The films were without any post-deposition annealing. The films grown on both kinds of substrates have anatase structure. However, the films grown on LAO substrates have (0 0 1) predominant orientation compared to a higher content of (1 1 2) orientation in the films grown on sapphire. TNO/LAO films showed low resistivities (~10-3 Ω cm at room temperature) and a metallic-type electrical conductivity as opposed to higher resistivities (~10-2 Ω cm) and a thermally activated conductivity of TNO/sapphire layers. ALD growth mechanisms of TNO films on crystalline substrates were described.

  8. Thin SiGe virtual substrates for Ge heterostructures integration on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Cecchi, S., E-mail: stefano.cecchi@mdm.imm.cnr.it; Chrastina, D.; Frigerio, J.; Isella, G. [L-NESS, Dipartimento di Fisica, Politecnico di Milano–Polo Territoriale di Como, Via Anzani 42, I-22100 Como (Italy); Gatti, E.; Guzzi, M. [L-NESS, Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, via Cozzi 53, I-20126 Milano (Italy); Müller Gubler, E. [Electron Microscopy ETH Zurich, ETH Zurich, Auguste-Piccard-Hof 1, CH-8093 Zurich (Switzerland); Paul, D. J. [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT (United Kingdom)

    2014-03-07

    The possibility to reduce the thickness of the SiGe virtual substrate, required for the integration of Ge heterostructures on Si, without heavily affecting the crystal quality is becoming fundamental in several applications. In this work, we present 1 μm thick Si{sub 1−x}Ge{sub x} buffers (with x > 0.7) having different designs which could be suitable for applications requiring a thin virtual substrate. The rationale is to reduce the lattice mismatch at the interface with the Si substrate by introducing composition steps and/or partial grading. The relatively low growth temperature (475 °C) makes this approach appealing for complementary metal-oxide-semiconductor integration. For all the investigated designs, a reduction of the threading dislocation density compared to constant composition Si{sub 1−x}Ge{sub x} layers was observed. The best buffer in terms of defects reduction was used as a virtual substrate for the deposition of a Ge/SiGe multiple quantum well structure. Room temperature optical absorption and photoluminescence analysis performed on nominally identical quantum wells grown on both a thick graded virtual substrate and the selected thin buffer demonstrates a comparable optical quality, confirming the effectiveness of the proposed approach.

  9. Growth and characterization of a multi-dimensional ZnO hybrid structure on a glass substrate by using metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae-Sik; Lee, Do-Han; Lee, Je-Haeng; Byun, Dong-Jin [Korea University, Seoul (Korea, Republic of)

    2014-05-15

    A multi-dimensional zinc oxide (ZnO) hybrid structure was successfully grown on a glass substrate by using metal organic chemical vapor deposition (MOCVD). The ZnO hybrid structure was composed of nanorods grown continuously on the ZnO film without any catalysts. The growth mode could be changed from a two-dimensional (2D) film to one-dimensional (1D) nanorods by simply controlling the substrate's temperature. The ZnO with a hybrid structure showed improved electrical and optical properties. The ZnO hybrid structure grown by using MOCVD has excellent potential for applications in opto-electronic devices and solar cells as anti-reflection coatings (ARCs), transparent conductive oxides (TCOs) and transparent thin-film transistors (TTFTs).

  10. GaAs Photovoltaics on Polycrystalline Ge Substrates

    Science.gov (United States)

    Wilt, David M.; Pal, AnnaMaria T.; McNatt, Jeremiah S.; Wolford, David S.; Landis, Geoffrey A.; Smith, Mark A.; Scheiman, David; Jenkins, Phillip P.; McElroy Bruce

    2007-01-01

    High efficiency III-V multijunction solar cells deposited on metal foil or even polymer substrates can provide tremendous advantages in mass and stowage, particularly for planetary missions. As a first step towards that goal, poly-crystalline p/i/n GaAs solar cells are under development on polycrystalline Ge substrates. Organo Metallic Vapor Phase Epitaxy (OMVPE) parameters for pre-growth bake, nucleation and deposition have been examined. Single junction p/i/n GaAs photovoltaic devices, incorporating InGaP front and back window layers, have been grown and processed. Device performance has shown a dependence upon the thickness of a GaAs buffer layer deposited between the Ge substrate and the active device structure. A thick (2 m) GaAs buffer provides for both increased average device performance as well as reduced sensitivity to variations in grain size and orientation. Illumination under IR light (lambda > 1 micron), the cells showed a Voc, demonstrating the presence of an unintended photoactive junction at the GaAs/Ge interface. The presence of this junction limited the efficiency to approx.13% (estimated with an anti-refection coating) due to the current mismatch and lack of tunnel junction interconnect.

  11. Monitoring Liverworts to Evaluate the Effectiveness of Hydroriparian Buffers

    Science.gov (United States)

    Higgins, Kellina L.; Yasué, Maï

    2014-01-01

    In the coastal temperate rainforest of British Columbia (BC) in western Canada, government policies stipulate that foresters leave unlogged hydroriparian buffer strips up to 25 m on each side of streams to protect wildlife habitat. At present, studies on the effectiveness of these buffers focus on mammals, birds, and amphibians while there is comparably little information on smaller organisms such as liverworts in these hydroriparian buffers. To address this gap of knowledge, we conducted field surveys of liverworts comparing the percent cover and community composition in hydroriparian forested areas ( n = 4 sites, n = 32 plots with nested design) to hydroriparian buffer zones ( n = 4 sites, n = 32 plots). We also examined how substrate type affected the cover of liverworts. Liverwort communities in buffers were similar to those in riparian forest areas and most liverworts were found on downed wood. Thus, hydroriparian buffers of 25-35 m on each side in a coastal temperate rainforest effectively provide habitat for liverworts as long as downed wood is left intact in the landscape. Because liverworts are particularly sensitive to changes in humidity, these results may indicate that hydroriparian buffers are an effective management strategy for bryophytes and possibly for a range of other riparian species that are particularly sensitive to forestry-related changes in microclimate.

  12. Laser-direct process of Cu nano-ink to coat highly conductive and adhesive metallization patterns on plastic substrate

    Science.gov (United States)

    Min, Hyungsuk; Lee, Byoungyoon; Jeong, Sooncheol; Lee, Myeongkyu

    2016-05-01

    We here present a simple, low-cost laser-direct process to fabricate conductive Cu patterns on plastic substrate. A Cu nano-ink was synthesized using Cu formate as a precursor. The Cu ink spin-coated on a polyimide substrate was selectively sintered using a pulsed ultraviolet laser beam. The unexposed regions of the coated ink could be removed by rinsing the whole film in the dispersion agent of the synthesized ink, which revealed a conductive Cu pattern. This allowed sintering and patterning to be simultaneously accomplished, with a minimum line width of ~20 μm available. The fabricated pattern remained strongly adhesive to the substrate and exhibited only a slight increase in resistance even after 1000 bending cycles to a radius of curvature of 4.8 mm.

  13. Growth of Cu{sub 2}ZnSnS{sub 4} absorber layer on flexible metallic substrates for thin film solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Yazici, Sebnem [Department of Physics, Izmir Institute of Technology, Urla, Izmir 35430 (Turkey); Olgar, Mehmet Ali [Department of Physics, Karadeniz Technical University, Trabzon (Turkey); Akca, Fatime Gulsah; Cantas, Ayten; Kurt, Metin; Aygun, Gulnur; Tarhan, Enver [Department of Physics, Izmir Institute of Technology, Urla, Izmir 35430 (Turkey); Yanmaz, Ekrem [Department of Physics, Karadeniz Technical University, Trabzon (Turkey); Ozyuzer, Lutfi, E-mail: ozyuzer@iyte.edu.tr [Department of Physics, Izmir Institute of Technology, Urla, Izmir 35430 (Turkey)

    2015-08-31

    In this work, Cu{sub 2}ZnSnS{sub 4} (CZTS) absorber layers were fabricated using a two-stage process. Sequentially deposited Cu–Zn–Sn thin film layers on metallic foils were annealed in an Ar + S{sub 2(g)} atmosphere. We aimed to investigate the role of flexible titanium and molybdenum foil substrates in the growth mechanism of CZTS thin films. The Raman spectra and X-ray photoelectron spectroscopy analyses of the sulfurized thin films revealed that, except for the presence of Sn-based secondary phases, nearly pure CZTS thin films were obtained. Additionally, the intense and sharp X-ray diffraction peak from the (112) plane provided evidence of good crystallinity. Electron dispersive spectroscopy analysis indicated sufficient sulfur content but poor Zn atomic weight percentage in the films. Absorption and band-gap energy analyses were carried out to confirm the suitability of CZTS thin films as the absorber layer in solar cell applications. Hall effect measurements showed the p-type semiconductor behavior of the CZTS samples. Moreover, the back contact behavior of these metallic flexible substrates was investigated and compared. We detected formation of cracks in the CZTS layer on the molybdenum foils, which indicates the incompatibility of molybdenum's thermal expansion coefficient with the CZTS structure. We demonstrated the application of the magnetron sputtering technique for the fabrication of CZTS thin films on titanium foils having lightweight, flexible properties and suitable for roll-to-roll manufacturing for high throughput fabrication. Titanium foils are also cost competitive compared to molybdenum foils. - Highlights: • Growth of CZTS layer for thin film solar cell applications • CZTS growth on metallic flexible foil substrates by magnetron sputtering technique • Lightweight and flexible substrate is feasible for roll-to-roll manufacturing. • Crack formation on Mo foil substrate due to mismatch of CTE between Mo and CZTS • Ti foil is

  14. BUFFERS AND VEGETATIVE FILTER STRIPS

    Science.gov (United States)

    Buffers and filter strips are areas of permanent vegetation located within and between agricultural fields and the water courses to which they drain. These buffers are intended to intercept and slow runoff thereby providing water quality benefits. In addition, in many settings they are intended to...

  15. Preparation of alumina coatings on metallic nickel substrate using a room-temperature wet chemical pretreatment method

    International Nuclear Information System (INIS)

    Research highlights: → We have developed a new wet chemical pretreatment method for nickel surface roughening. → The nickel substrate etched for 3 min at room temperature has a high large surface area. → A crack-free primer coating and a slurry coating have very little tiny crack. → This pretreatment method can obtain well-adhered alumina coating. - Abstract: Electrodeposited nickel substrate was effectively micro-roughened with an acidic bath containing 5 wt% H2SO4 and 10 wt% (NH4)2S2O8 at room temperature. The uniformly roughened surface was then sequentially wash-coated with boehmite sol and alumina slurries. The microstructure and the surface performance of the wash-coat/substrate were investigated by scanning electron microscopy and ultrasonic vibration test. The nickel substrate that was etched for 3 min at room temperature yielded a foam-like roughened surface morphology with a high large surface area. A crack-free primer coating and a slurry coating with very little tiny crack can be prepared by using this convenient, energy-saving, and time-efficient pretreatment method.

  16. Preparation and Characterization of CeO2/YSZ/CeO2 Buffer Layers for YBCO Coated Conductors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CeO2 seed layer was deposited on rolling-assisted biaxially textured metal substrates by direct-current (DC) magnetron reactive sputtering. The effect of deposition temperature on epitaxial orientation of CeO2 thin films was examined. High quality CeO2 layers were achieved at deposition temperature from 750℃ to 850℃.Subsequently yttria-stabilized zirconia (YSZ) and CeO2 films were deposited to complete the buffer layer structure via the same process. The best samples exhibited a highly biaxial texture, as indicated by FWHM (full width half maximum) values in the range of 4°-5°, and 2°-4° for in-plane and out-of-plane orientations,respectively. Secondary ion mass spectrometer analysis confirmed the effective prevention of buffer layer against Ni and W metal interdiffusion. Atomic force microscope observations revealed a smooth, dense and crack-free surface morphology, which provided themselves as the good buffer structure to the YBa2Cu3O7-δ(YBCO) coated conductors.

  17. Electronic and magnetic properties of hybrid interfaces. From single molecules to ultra-thin molecular films on metallic substrates

    OpenAIRE

    Gruber, Manuel

    2014-01-01

    Understanding the properties of molecules at the interface with metals is a fundamental issue for organic spintronics. The first part of this thesis is devoted to the study of magnetic properties of planar manganese-phthalocyanine molecules and Co films. The second part of the thesis is focused on the study of a spin-crossover complex, Fe(phen)2(NCS)2 sublimed on different metallic surfaces.

  18. Electroless copper on refractory and noble metal substrates with an ultra-thin plasma-assisted atomic layer deposited palladium layer

    International Nuclear Information System (INIS)

    Electroless Cu was investigated on refractory metal, W and TaN X, and Ir noble metal substrates with a plasma-assisted atomic layer deposited palladium layer for the potential back-end-of-the-line (BEOL) metallization of advanced integrated devices. The sodium and potassium-free Cu electroless bath consisted of: ethylenediamine tetraacetic acid (EDTA) as a chelating agent, glyoxylic acid as a reducing agent, and additional chemicals such as polyethylene glycol, 2,2'-dipyridine and RE-610 as surfactant, stabilizer and wetting agent respectively. The growth and chemical characterization of the Cu films was carried out with a field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS). Group VIII metals such as Pt, Pd, etc., are stable in the electroless bath and catalytic towards the oxidation of glyoxylic acid and therefore work well for the electroless deposition of Cu. From RBS analysis, the amount of carbon and oxygen in Cu films were less than 1-3%. The Cu films were electroless deposited at 45-50 deg. C on patterned tantalum nitride with plasma-assisted atomic layer deposited (PA-ALD) Pd as a catalytic layer. Electroless Cu trench fill was successful with ultrasonic vibration, RE-610, and lowering the temperature to 45-50 deg. C on TaN X with the PA-ALD Pd catalytic layer

  19. Variation of power generation at different buffer types and conductivities in single chamber microbial fuel cells

    KAUST Repository

    Nam, Joo-Youn

    2010-01-15

    Microbial fuel cells (MFCs) are operated with solutions containing various chemical species required for the growth of electrochemically active microorganisms including nutrients and vitamins, substrates, and chemical buffers. Many different buffers are used in laboratory media, but the effects of these buffers and their inherent electrolyte conductivities have not been examined relative to current generation in MFCs. We investigated the effect of several common buffers (phosphate, MES, HEPES, and PIPES) on power production in single chambered MFCs compared to a non-buffered control. At the same concentrations the buffers produced different solution conductivities which resulted in different ohmic resistances and power densities. Increasing the solution conductivities to the same values using NaCl produced comparable power densities for all buffers. Very large increases in conductivity resulted in a rapid voltage drop at high current densities. Our results suggest that solution conductivity at a specific pH for each buffer is more important in MFC studies than the buffer itself given relatively constant pH conditions. Based on our analysis of internal resistance and a set neutral pH, phosphate and PIPES are the most useful buffers of those examined here because pH was maintained close to the pKa of the buffer, maximizing the ability of the buffer to contribute to increase current generation at high power densities. © 2009 Elsevier B.V. All rights reserved.

  20. Heuristics for the Buffer Allocation Problem with Collision Probability Using Computer Simulation

    Directory of Open Access Journals (Sweden)

    Eishi Chiba

    2015-01-01

    Full Text Available The standard manufacturing system for Flat Panel Displays (FPDs consists of a number of pieces of equipment in series. Each piece of equipment usually has a number of buffers to prevent collision between glass substrates. However, in reality, very few of these buffers seem to be used. This means that redundant buffers exist. In order to reduce cost and space necessary for manufacturing, the number of buffers should be minimized with consideration of possible collisions. In this paper, we focus on an in-line system in which each piece of equipment can have any number of buffers. In this in-line system, we present a computer simulation method for the computation of the probability of a collision occurring. Based on this method, we try to find a buffer allocation that achieves the smallest total number of buffers under an arbitrarily specified collision probability. We also implement our proposed method and present some computational results.

  1. Effect of Substrate Movement Speed by Synchronous Rolling-casting Freeform Manufacturing for Metal on Microstructure and Mechanical Property of ZLl04 Aluminum Alloy Slurry

    Institute of Scientific and Technical Information of China (English)

    LUO Xiaoqiang; LI Zhengyang; CHEN Guangnan; XU Wanli; YAN Qingzhi

    2015-01-01

    Synchronous rolling-casting freeform manufacturing for Metal (SRCFMM) means that the refined liquid metal is continuously pressed out from the bottom of crucible. There is a horizontal movable plate beneath the outlet. The clearance between the outlet and the plate is about several hundred micrometers. SRCFMM, similar to additive manufacturing, implies layer by layer shaping and consolidation of feedstock to arbitrary conifgurations, normally using a computer controlled movable plate. The primary dendritic crystal is easily crushed by movement of substrate in the rolling-casting area. ZL104 was used as the test materials, determi-ning the control temperature by differential scanning thermal analysis (DSC), preparing a kind of samples by SR CFMM, then analyzing microstructures and mechanical property of the samples. Characteristics and distribution of the primary particles were assessed by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) and image analysis software. Mechanical property of the samples was assessed by vickers hardness. The results show that the samples fabricated by SRCFMM have uniform structures and good performances with the velocity of the substrate controlled about 10 cm/s and temperature at about 580℃.

  2. Optimization of Grit-Blasting Process Parameters for Production of Dense Coatings on Open Pores Metallic Foam Substrates Using Statistical Methods

    Science.gov (United States)

    Salavati, S.; Coyle, T. W.; Mostaghimi, J.

    2015-10-01

    Open pore metallic foam core sandwich panels prepared by thermal spraying of a coating on the foam structures can be used as high-efficiency heat transfer devices due to their high surface area to volume ratio. The structural, mechanical, and physical properties of thermally sprayed skins play a significant role in the performance of the related devices. These properties are mainly controlled by the porosity content, oxide content, adhesion strength, and stiffness of the deposited coating. In this study, the effects of grit-blasting process parameters on the characteristics of the temporary surface created on the metallic foam substrate and on the twin-wire arc-sprayed alloy 625 coating subsequently deposited on the foam were investigated through response surface methodology. Characterization of the prepared surface and sprayed coating was conducted by scanning electron microscopy, roughness measurements, and adhesion testing. Using statistical design of experiments, response surface method, a model was developed to predict the effect of grit-blasting parameters on the surface roughness of the prepared foam and also the porosity content of the sprayed coating. The coating porosity and adhesion strength were found to be determined by the substrate surface roughness, which could be controlled by grit-blasting parameters. Optimization of the grit-blasting parameters was conducted using the fitted model to minimize the porosity content of the coating while maintaining a high adhesion strength.

  3. Growth of TiO2 anti-reflection layer on textured Si (100) wafer substrate by metal-organic chemical vapor deposition method.

    Science.gov (United States)

    Nam, Sang-Hun; Choi, Jin-Woo; Cho, Sang-Jin; Kimt, Keun Soo; Boo, Jin-Hyo

    2011-08-01

    Recently anti-reflective films (AR) have been intensely studied. Particularly for textured silicon solar cells, the AR films can further reduce the reflection of the incident light through trapping the incident light into the cells. In this work, TiO2 anti-reflection films have been grown on the textured Si (100) substrate which is processed in two steps, and the films are deposited using metal-organic chemical vapor deposition (MOCVD) with a precursor of titanium tetra-isopropoxide (TTIP). The effect of the substrate texture and the growth conditions of TiO2 films on the reflectance has been investigated. Pyramid size of textured silicon had approximately 2-9 microm. A well-textured silicon surface can lower the reflectance to 10%. For more reduced reflection, TiO2 anti-reflection films on the textured silicon were deposited at 600 degrees C using titanium tetra-isopropoxide (TTIP) as a precursor by metal-organic chemical vapor deposition (MOCVD), and the deposited TiO2 layers were then treated by annealing for 2 h in air at 600 and 1000 degrees C, respectively. In this process, the treated samples by annealing showed anatase and rutile phases, respectively. The thickness of TiO2 films was about 75 +/- 5 nm. The reflectance at specific wavelength can be reduced to 3% in optimum layer. PMID:22103185

  4. Buffering capacity: its relevance in soil and water pollution

    Energy Technology Data Exchange (ETDEWEB)

    Stigliani, W.M. [University of Northern Iowa, Cedar Falls (United States)

    1996-02-01

    Buffering capacities in soils are essential for neutralizing or immobilizing inputs of acids and heavy metals. There are four major buffering regimes, each of which operates in a defined pH range. When the rate of pollutant inputs exceeds the rate of natural replenishment of the buffer in a specific regime, the supply of buffer will be exhausted over time, and the soil may switch to a regime at lower pH. As the pH of the soil declines, so does its capacity to immobilize heavy metals. If the soil initially has a moderately high buffering capacity, the time scale before exhaustion is on the order of decades to a century. Over this time there may be no observable environmental effects. When the effects do become obvious, it may be too late to reverse the damage. The importance of buffering capacity as a valued environmental resource must be recognized, and its preservation must be a major component of long-term soil protection policies. (Author). 17 refs., 6 figs., 1 tab.

  5. Metal Decoration Effects on the Gas-Sensing Properties of 2D Hybrid-Structures on Flexible Substrates

    Directory of Open Access Journals (Sweden)

    Byungjin Cho

    2015-09-01

    Full Text Available We have investigated the effects of metal decoration on the gas-sensing properties of a device with two-dimensional (2D molybdenum disulfide (MoS2 flake channels and graphene electrodes. The 2D hybrid-structure device sensitively detected NO2 gas molecules (>1.2 ppm as well as NH3 (>10 ppm. Metal nanoparticles (NPs could tune the electronic properties of the 2D graphene/MoS2 device, increasing sensitivity to a specific gas molecule. For instance, palladium NPs accumulate hole carriers of graphene/MoS2, electronically sensitizing NH3 gas molecules. Contrarily, aluminum NPs deplete hole carriers, enhancing NO2 sensitivity. The synergistic combination of metal NPs and 2D hybrid layers could be also applied to a flexible gas sensor. There was no serious degradation in the sensing performance of metal-decorated MoS2 flexible devices before/after 5000 bending cycles. Thus, highly sensitive and endurable gas sensor could be achieved through the metal-decorated 2D hybrid-structure, offering a useful route to wearable electronic sensing platforms.

  6. Pb-Free Glass Paste: A Metallization-Free Die-Attachment Solution for High-Temperature Application on Ceramic Substrates

    Science.gov (United States)

    Sharif, Ahmed; Lim, Jun zhang; Made, Riko I.; Lau, Fu Long; Phua, Eric Jian Rong; Lim, Ju Dy; Wong, Chee Cheong; Gan, Chee Lip; Chen, Zhong

    2013-08-01

    A lead-free glass frit paste as a die-attach material for high-temperature microelectronic application is proposed in this study. The glass paste containing Bi-based powder with a moderate amount of solvent was used for joining Si dice on ceramic substrates without any metallization preparation for either of the bonding surfaces. The die was bonded to a ceramic substrate at 430°C for 10 min. The study focuses on the mechanical and microstructural characterization of the joints with Si dice on two different types of ceramic substrate. Shear strength measurements were carried out at both ambient and 250°C to evaluate room- and high-temperature performance. Furthermore, the effect of aging at 300°C for 500 h on the mechanical properties is presented. The results of the mechanical and microstructural characterization demonstrate that low-temperature glass frit bonding is an effective die-attach method for harsh-environment electronic packaging.

  7. Growth of TiO2 nanorods on a Ta substrate by metal-organic chemical vapor deposition.

    Science.gov (United States)

    Lee, Kang Suk; Hyun, Jae-Sung; Seo, Hyun Ook; Kim, Young Dok; Boo, Jin-Hyo

    2010-05-01

    TiO2 nanorods were successfully grown on Tantalum (Ta) substrates using titanium tetra isopropoxide (TTIP) as a single precursor without any carriers or bubbling gases. For characterization of the TiO2 structures, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed. For substrate temperatures below 800 degrees C, a rough film structure without nanorods could be found. However, at a sample temperature of 800 degrees C, nanorod structures with a respective diameter and length of 0.1 approximately 0.2 microm and 0.7 approximately 1.5 microm, respectively, could be synthesized. The nanorods exhibited a rutile phase with a 2:1 stoichiometry of O:Ti, identified using XRD and XPS. When the growth temperature exceeded 800 degrees C, agglomeration of the nanorods was identified. PMID:20358953

  8. A study of the initial stages of the electrochemical deposition of metals on foreign substrates: Lead and thallium on copper and silver surfaces: General discussion

    Directory of Open Access Journals (Sweden)

    Jovićević Jovan N.

    2005-01-01

    Full Text Available The basic applicability of the UPD theory of Gerischer et al. has been confirmed in the case of lead and thallium deposition on copper and silver single crystals, but it was shown also that this is only one of the important factors. It was established that the effect of substrate structure on the mechanism of the UPD monolayer formation plays an important role in the addition to the effect of electronegativity difference between the substrate and depositing atoms. An effect of changing the concentration of depositing metal and specifically adsorbing anion were found and attributed to the changes in the electronegativity of the substrate and underpotential layer as a result of changing the electrode potential. It was conclusively proven by the analysis of the peaked current-time transients obtained by potential step measurements and the very sharp voltammetry peaks, that first order 2D phase transformations are possible in UPD systems. It was also found that the L.S.V. peaks reflecting such processes must not be expected to be free from the influence of slow kinetics. It was established that the 2D crystalline metal-like phases with the closest-packed epitaxial structure exist as a stable, final product in UPD. Moreover, the possibility of higher order 2D transformations in UPD has been given strong support by the evidence of gradual monolayer density change with increasing driving force. Lead UPD on vitreous carbon was found to be the result of substrate reconstruction induced by the repeated deposition and dissolution leading to surface condition changes favoring deposition of the first layer. UPD monolayers on copper and silver surfaces always preceded OPD and had a profound effect on its nucleation overpotential (making it very small indeed or even changing its character from 3D into 2D (in the case of vitreous carbon substrate. It was also shown that lead and thallium OPD on copper and silver single crystals starts off by charge transfer

  9. Scanning Tunneling Spectroscopic Studies of the Effects of Dielectrics and Metallic Substrates on the Local Electronic Characteristics of Graphene

    OpenAIRE

    Yeh, N.-C.; Teague, M.-L.; Boyd, D A; Bockrath, M. W.; Velasco, J.; Lau, C.-N.

    2010-01-01

    Atomically resolved imaging and spectroscopic characteristics of graphene grown by chemical vapor deposition (CVD) on copper foils are investigated and compared with those of mechanical exfoliated graphene on SiO_2. For exfoliated graphene, the local spectral deviations from ideal behavior may be attributed to strain induced by the SiO_2 substrate. For CVD grown graphene, the lattice structure appears strongly distorted by the underlying copper, with regions in direct con...

  10. The effect of Cr buffer layer thickness on voltage generation of thin-film thermoelectric modules

    International Nuclear Information System (INIS)

    The effect of Cr buffer layer thickness on the open-circuit voltage generated by thin-film thermoelectric modules of Bi0.5Sb1.5Te3 (p-type) and Bi2Te2.7Se0.3 (n-type) materials was investigated. A Cr buffer layer, whose thickness generally needs to be optimized to improve adhesion depending on the substrate surface condition, such as roughness, was deposited between thermoelectric thin films and glass substrates. When the Cr buffer layer was 1 nm thick, the Seebeck coefficients and electrical conductivity of 1 µm thermoelectric thin films with the buffer layers were approximately equal to those of the thermoelectric films without the buffer layers. When the thickness of the Cr buffer layer was 1 µm, the same as the thermoelectric films, the Seebeck coefficients of the bilayer films were reduced by an electrical current flowing inside the Cr buffer layer and the generation of Cr2Te3. The open-circuit voltage of the thin-film thermoelectric modules decreased with an increase in the thickness of the Cr buffer layer, which was primarily induced by the electrical current flow. The reduction caused by the Cr2Te3 generation was less than 10% of the total voltage generation of the modules without the Cr buffer layers. The voltage generation of thin-film thermoelectric modules could be controlled by the Cr buffer layer thickness. (paper)

  11. Evaluation of shear bond strengths of gingiva-colored composite resin to porcelain, metal and zirconia substrates

    OpenAIRE

    An, Hong-Seok; Park, Ji-Man; Park, Eun-Jin

    2011-01-01

    PURPOSE The purpose of this study is to evaluate and compare the shear bond strength of the gingiva-colored composite resin and the tooth-colored composite resin to porcelain, metal and zirconia. MATERIALS AND METHODS Sixty cylindrical specimens were fabricated and divided into the following 6 groups (Group 1-W: tooth-colored composite bonded to porcelain, Group 1-P: gingiva-colored composite bonded to porcelain, Group 2-W: tooth-colored composite bonded to base metal, Group 2-P: gingiva-colo...

  12. PLZT capacitor on glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Fairchild, Manuel Ray; Taylor, Ralph S.; Berlin, Carl W.; Wong, Celine Wk; Ma, Beihai; Balachandran, Uthamalingam

    2016-03-29

    A lead-lanthanum-zirconium-titanate (PLZT) capacitor on a substrate formed of glass. The first metallization layer is deposited on a top side of the substrate to form a first electrode. The dielectric layer of PLZT is deposited over the first metallization layer. The second metallization layer deposited over the dielectric layer to form a second electrode. The glass substrate is advantageous as glass is compatible with an annealing process used to form the capacitor.

  13. EXAMINATION OF DISLOCATIONS IN LATTICE-MISMATCHED GaInAs/BUFFER LAYER/GaAs FOR III-V PHOTOVOLTAICS

    Energy Technology Data Exchange (ETDEWEB)

    Levander, A.; Geisz, J.

    2007-01-01

    Dislocations act as sites for nonradiative electron/hole pair recombination, which reduces the effi ciency of photovoltaics. Lattice-matched materials can be grown on top of one another without forming a high density of dislocations. However, when the growth of lattice-mismatched (LMM) materials is attempted, many dislocations result from the relaxation of strain in the crystal structure. In an attempt to reduce the number of dislocations that propagate into a solar device when using LMM materials, a compositionally step-graded buffer is placed between the two LMM materials. In order to confi ne the dislocations to the buffer layer and therefore increase material quality and device effi ciency, the growth temperature and thickness of the buffer layer were varied. A GaInP compositionally graded buffer and GaInAs p-n junction were grown on a GaAs substrate in a metal-organic chemical vapor deposition (MOCVD) system. A multibeam optical stress sensor (MOSS) and X-ray diffraction (XRD) were used to characterize the strain in the epilayers. Electrical and optoelectronic properties were measured using a probe station and multimeter setup, solar simulator, and a quantum effi ciency instrument. It was determined that device functionality was highly dependent on the growth temperature of the graded buffer. As growth temperature increased, so did the dislocation density in the device despite an increase in the dislocation velocity, which should have increased the dislocation annihilation rate and the diffusion of dislocations to the edge of the crystal. The thickness of the graded buffer also affected device effi ciency with thinner samples performing poorly. The thinner graded buffer layers had high internal resistances from reduced carrier concentrations. In terms of effi ciency, the empirically derived recipe developed by the scientists at the National Renewable Energy Laboratory (NREL) produced the highest quality cells.

  14. Studies of metal ammonia interactions with aromatic substrates: Progress report for the period February 1, 1987 to December 31, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Rabideau, P.W.

    1987-07-01

    This report details the accomplishments since the previous report which was submitted for the activities of 1986. A brief description is provided relating to publications and presentations. Technical work in progress which is not available in reprint form is also described. This includes metal-ammonia reduction results, NMR analysis of hydroaromatics and theoretical calculations on hydroaromatics anions.

  15. Heat conductivity of buffer materials

    International Nuclear Information System (INIS)

    The report deals with the thermal conductivity of bentonite based buffer materials. An improved technique for measuring the thermal conductivity of buffer materials is described. Measurements of FLAC calculations applying this technique have led to a proposal of how standardized tests should be conducted and evaluated. The thermal conductivity of bentonite with different void ratio and degree of water saturation has been determined in the following different ways: * Theoretically according to three different investigations by other researchers. * Laboratory measurements with the proposed method. * Results from back-calculated field tests. Comparison and evaluation showed that these results agreed very well, when the buffer material was almost water saturated. However, the influence of the degree of saturation was not very well predicted with the theoretical methods. Furthermore, the field tests showed that the average thermal conductivity in situ of buffer material (compacted to blocks) with low degree of water saturation was lower than expected from laboratory tests. 12 refs, 29 figs, 11 tabs

  16. Evaluation of methods for application of epitaxial layers of superconductor and buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-06-01

    The recent achievements in a number of laboratories of critical currents in excess of 1.0x10{sup 6} amp/cm{sup 2} at 77K in YBCO deposited over suitably textured buffer/substrate composites have stimulated interest in the potential applications of coated conductors at high temperatures and high magnetic fields. As of today, two different approaches for obtaining the textured substrates have been identified. These are: Los Alamos National Laboratory`s (LANL) ion-beam assisted deposition called IBAD, to obtain a highly textured yttria-stabilized zirconia (YSZ) buffer on nickel alloy strips, and Oak Ridge National Laboratory`s (ORNL) rolling assisted, bi-axial texturized substrate option called RABiTS. Similarly, based on the published literature, the available options to form High Temperature Superconductor (HTS) films on metallic, semi-metallic or ceramic substrates can be divided into: physical methods, and non-physical or chemical methods. Under these two major groups, the schemes being proposed consist of: - Sputtering - Electron-Beam Evaporation - Flash Evaporation - Molecular Beam Epitaxy - Laser Ablation - Electrophoresis - Chemical Vapor Deposition (Including Metal-Organic Chemical Vapor Deposition) - Sol-Gel - Metal-Organic Decomposition - Electrodeposition, and - Aerosol/Spray Pyrolysis. In general, a spool- to-spool or reel-to-reel type of continuous manufacturing scheme developed out of any of the above techniques, would consist of: - Preparation of Substrate Material - Preparation and Application of the Buffer Layer(s) - Preparation and Application of the HTS Material and Required Post-Annealing, and - Preparation and Application of the External Protective Layer. These operations would be affected by various process parameters which can be classified into: Chemistry and Material Related Parameters; and Engineering and Environmental Based Parameters. Thus, one can see that for successful development of the coated conductors manufacturing process, an

  17. Evaluation of methods for application of epitaxial buffer and superconductor layers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-30

    The recent achievements of critical currents exceeding million amperes per square centimeter at 77K in YBCO deposited over suitably textured substrate have stimulated interest in the potential applications of coated conductors at high temperatures and in high magnetic fields. Currently, ion-beam assisted deposition (IBAD), and rolling assisted bi-axially textured substrate (RABiTS), represent two available options for obtaining textured substrates. For applying suitable coatings of buffer and high temperature superconductor (HTS) material over textured substrates, several options are available which include sputtering, electron-beam evaporation, laser ablation, electrophoresis, chemical vapor deposition (including metal organics chemical vapor deposition), sol-gel, metal organics decomposition, electrodeposition and aerosol/spray pyrolysis. A commercial continuous long-length wire/tape manufacturing scheme developed out of any suitable combination of the above techniques would consist of operations involving preparation of the substrate and application of buffer, HTS and passivation/insulation materials and special treatment steps such as post-annealing. These operations can be effected by various process parameters that can be classified into chemistry, materials, engineering and environmental related parameters. Under the DOE-sponsored program, to carry out an engineering evaluation, first, the process flow schemes were developed for various candidate options identifying the major operating steps, process conditions, and process streams. Next, to evaluate quantifiable parameters such as process severity (e.g. temperature and pressure), coating thickness and deposition rate for HTS material, achieved maximum J{sub c} value (for films >1{micro}m thick) and cost of chemical and material utilization efficiency, the multi-attribute method was used to determine attributes/merits for various parameters and candidate options. To determine similar attribute values for the

  18. Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

    International Nuclear Information System (INIS)

    A highly dense, 4 μm-thick Pb(Zr,Ti)O3 (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longer-wavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas film-composites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices

  19. Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Palneedi, Haribabu [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Functional Ceramics Group, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of); Maurya, Deepam; Priya, Shashank [Bio-inspired Materials and Devices Laboratory (BMDL), Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Kim, Gi-Yeop; Choi, Si-Young, E-mail: youngchoi@kims.re.kr [Materials Modeling and Characterization Department, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of); Kang, Suk-Joong L. [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Kim, Kwang-Ho [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Ryu, Jungho, E-mail: jhryu@kims.re.kr [Functional Ceramics Group, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of)

    2015-07-06

    A highly dense, 4 μm-thick Pb(Zr,Ti)O{sub 3} (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longer-wavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas film-composites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices.

  20. Characteristics of ion spectrum in a low energy nitrogen operated plasma focus: application to the metallic substrates thermal treatment

    International Nuclear Information System (INIS)

    Full text: This work presents the nitrogen ion spectrum characteristics in a Plasma Focus device, determined using a Thomson spectrometer and a Faraday cup, operated in the secondary electron collective mode. It is also discussed the thermal treatment and the re coating induce by ions incident on a metallic surface (AISI 304 steel) placed in front of the coaxial gun, when the device is operated with a Ti implant at the end of the central electrode