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Sample records for cu-al bilayer films

  1. A metastable HCP intermetallic phase in Cu-Al bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Limei

    2006-07-01

    For the present study, three kinds of layered Cu/Al films have been fabricated. The first kind of samples were multilayered Cu/Al films deposited by sputtering on (001)Si. The individual layer thicknesses were 100 nm, 200 nm and 400 nm, while the total film thickness of 800 nm was kept constant, thus leading to multilayer systems with 8, 4 and 2 layers, respectively. The second type of samples were Cu/Al bilayer films grown on (0001) sapphire by sputtering, with individual layer thicknesses of 400 nm. The third type of samples were bilayer films (100 nm Cu and 100 nm Al) deposited on (0001)sapphire by MBE at room temperature. Applying conventional transmission electron microscopy and X-ray diffraction, different epitaxial growth behaviors were found in these films. All multilayer films from the first type were polycrystalline. The second type of films show a (111) FCC texture and possess intermetallic phases at the interfaces. HRTEM investigations displayed that along [111]FCC, the atomic structure of the interlayer has an ABAB stacking sequence, which is identical with a hexagonal close-packed (HCP) structure in [0001] direction, but not with the ABCABC stacking sequence of Cu and Al in [111]FCC. The lattice parameters of the HCP structure at the interlayer were determined from a model which gave the best agreement between the experimental and simulated images. The parameters are: a=b=0.256 nm, c=0.419 nm, ?=120 , with the space group of P6m2. Furthermore, lattice distortion analysis revealed that the lattice parameters of the HCP phase are increasing from the near-Cu-side to the near-Al-side. The chemical composition of the interlayer was investigated by energy dispersive X-ray spectroscopy (EDS). EDS linescans were performed from pure Al to pure Cu layers. In order to examine the stability of this HCP phase, in-situ heating experiments were performed in the HRTEM at {proportional_to}600 C. Ex-situ heating experiments were performed at different temperatures to

  2. Delafossite-CuAlO{sub 2} films prepared by annealing of amorphous Cu-Al-O films at high temperature under controlled atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hong-Ying, E-mail: hychen@cc.kuas.edu.tw; Tsai, Ming-Wei

    2011-07-01

    In this study, amorphous Cu-Al-O films were deposited onto a (100) p-type silicon substrate by a magnetron sputtering system. The films were then annealed at 700 deg. C and 800 deg. C for 2 h in N{sub 2}, air and O{sub 2}. X-ray diffraction patterns showed that the as-deposited films were amorphous. When the films were annealed at 700 deg. C, the monoclinic-CuO and spinel-CuAl{sub 2}O{sub 4} phases were detected in all atmospheres. As the annealing temperature increased to 800 deg. C, delafossite-CuAlO{sub 2} (R3-bar m and P6{sub 3}/mmc phases) appeared in N{sub 2} whereas monoclinic-CuO and spinel-CuAl{sub 2}O{sub 4} phases were detected in air and O{sub 2}. Thermodynamic calculations can explain the formation of delafossite-CuAlO{sub 2} films. The optical bandgap and conductivity of delafossite-CuAlO{sub 2} films were 3.30 eV and 6.8 x 10{sup -3} S/cm, respectively, which are compatible with other data in the literature. The p-type characteristic in delafossite-CuAlO{sub 2} films was verified by a hot-probe method.

  3. New type of Schottky diode-based Cu-Al-Mn-Cr shape memory material films

    Science.gov (United States)

    Aksu Canbay, C.; Dere, A.; Mensah-Darkwa, Kwadwo; Al-Ghamdi, Ahmed; Karagoz Genç, Z.; Gupta, R. K.; Yakuphanoglu, F.

    2016-07-01

    Cr-doped CuAlMn shape memory alloys were produced by arc melting method. The effects of Cr content on microstructure and transformation parameters of were investigated. The alloys were characterized by X-ray analysis, optical microscope observations and differential scanning calorimetry measurements. The grain size of the alloys was decreased by the addition of Cr into CuAlMn alloy system. The martensite transformation temperature was shifted both the lower temperature and higher temperature with the addition of chromium. This change was explained on the basis of the change in the thermodynamics such as enthalpy, entropy and activation energy values. The obtained results indicate that the phase transformation temperatures of the CuAlMn alloy system can be controlled by addition of Cr. We fabricated a Schottky barrier diode and observed that ideality factor and barrier height increase with increasing temperature. The diodes exhibited a thermal sensor behavior. This indicates that Schottky diode-based Cu-Al-Mn-Cr shape memory material films can be used as a sensor in high-temperature measurement applications.

  4. Formation of CuAlO2 Film by Ultrasonic Spray Pyrolysis

    Science.gov (United States)

    Iping, S.; Lockman, Zainovia; Hutagalung, S. D.; Kamsul, A.; Matsuda, Atsunori

    2011-10-01

    Smooth, crack free and homogenous CuAlO2 film was produced by chemical solution deposition process via spray pyrolysis technique on a cleaned Si substrate. The precursor solution used was comprised of a mixture of 45.87 mmol Cu(NO3)2.3H2O and 90 mmol Al(NO3)3.9H2O at ratio of Cu:Al = 1.2:1. The precursor solution was placed in a mist chamber and was atomized by a nebulizer to produce precursor mist. The precursor mist was then carried out by Ar gas and was sprayed onto a heated Si. Two main parameters were studied: the distance between the nozzle of the precursor mist chamber and the Si and the temperature of the Si substrate. It appears that from the XRD data, CuAlO2 can be detected for samples prepared by spraying the precursor mist at temperature of > 550 °C with distance between the nozzle and the substrate of 3cm. Reaction of the Cu and Al ions in the mist near the substrate may have promoted the crystallisation of CuAlO2.

  5. Formation of CuAlO{sub 2} Film by Ultrasonic Spray Pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Iping, S; Lockman, Zainovia; Hutagalung, S D [School of Materials and Mineral Resources, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Kamsul, A [Gadjah Mada University, Faculty of Mathematics and Natural Resources, Department of Physics, Sekip Utara Bulaksumur 55281 Yogyakarta (Indonesia); Matsuda, Atsunori, E-mail: zainovia@eng.usm.my [Toyohashi University of Technology, Faculty of Engineering, Department of Materials Science, 1-1 Hibarigaoka, Tempakucho, Toyohashi-shi, Aichi 441-8580 (Japan)

    2011-10-29

    Smooth, crack free and homogenous CuAlO{sub 2} film was produced by chemical solution deposition process via spray pyrolysis technique on a cleaned Si substrate. The precursor solution used was comprised of a mixture of 45.87 mmol Cu(NO{sub 3}){sub 2}.3H{sub 2}O and 90 mmol Al(NO{sub 3}){sub 3}.9H{sub 2}O at ratio of Cu:Al = 1.2:1. The precursor solution was placed in a mist chamber and was atomized by a nebulizer to produce precursor mist. The precursor mist was then carried out by Ar gas and was sprayed onto a heated Si. Two main parameters were studied: the distance between the nozzle of the precursor mist chamber and the Si and the temperature of the Si substrate. It appears that from the XRD data, CuAlO{sub 2} can be detected for samples prepared by spraying the precursor mist at temperature of > 550 deg. C with distance between the nozzle and the substrate of 3cm. Reaction of the Cu and Al ions in the mist near the substrate may have promoted the crystallisation of CuAlO{sub 2}.

  6. The structure of Cu-Al films prepared by unbalanced DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J.; Bell, A.J. [Czech Acad. of Sci., Prague (Czech Republic). Inst. of Phys.; Chepera, M.; Zeman, J. [Military Technical Institute, PO Box 574, 602 00 (Czech Republic)

    1997-11-25

    Recently, the formation of nanostructured and amorphous materials has been the focus of intense research owing to interest from a basic scientific point of view and their potential technological value. This paper reports on the variation in, and control of, the structure of Cu-Al films prepared in a state-of-the-art unbalanced DC magnetron sputtering system. The structure is shown to be considerably influenced by ion bombardment during growth with both the energy and ratio of impinging ions: arriving atoms playing dominant roles. In addition, the addition of different quantities of Al to the thin film is shown to have a dramatic impact on the structure. The conditions under which nanocrystalline Cu-Al films can be prepared are given. The films were deposited by the magnetron sputter ion plating (MSIP) process using negative substrate biases up to 1000 V and at different argon pressures down to 0.04 Pa. The structure of the films were determined from XRD analyses. An attempt to correlate obtained XRD spectra with the structure of the film is suggested. The resistivities of the films were measured using the four-point probe method, whilst the content of Al was determined from EDX measurements. (orig.) 15 refs.

  7. Preparation of CuAlO2 Thin Films by Sol-Gel Method Using Nitrate Solution Dip-Coating

    Directory of Open Access Journals (Sweden)

    Ehara Takashi

    2016-01-01

    Full Text Available CuAlO2 thin films are prepared by sol-gel dip-coating followed by annealing in nitrogen atmosphere using copper nitrate and aluminum nitrate as metal source materials. X-ray diffraction (XRD patterns show (003, (006 and (009 oriented peaks of CuAlO2 at annealing temperature of 800 – 1000°C. This result indicates that the CuAlO2 films prepared in the present work are c-axis oriented. XRD peak intensity increase with annealing temperature and becomes maximum at 850°C. The CuAlO2 XRD peak decreased at annealing temperature of 900°C with appearance of a peak of CuO, and then increased again with annealing temperature until 1000 °C. The films have bandgap of 3.4 eV at annealing temperature of 850°C in which the transparency becomes the highest. At the annealing temperature of 850°C, scanning electron microscope (SEM observation reveals that the films are consist of amorphous fraction and microcrystalline CuAlO2 fraction.

  8. Study of the growth of CuAlS{sub 2} thin films on oriented silicon (111)

    Energy Technology Data Exchange (ETDEWEB)

    Brini, R. [Laboratoire de Photovoltaique et Materiaux Semiconducteurs.(LPMS), Ecole Nationale d' ingenieurs de Tunis (ENIT), BP 37 le Belvedere 1002 Tunis (Tunisia)], E-mail: Brini_rawdha@yahoo.fr; Schmerber, G. [Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS) UMR7504 CNRS-ULP, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France); Kanzari, M. [Laboratoire de Photovoltaique et Materiaux Semiconducteurs.(LPMS), Ecole Nationale d' ingenieurs de Tunis (ENIT), BP 37 le Belvedere 1002 Tunis (Tunisia); Werckmann, J. [Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS) UMR7504 CNRS-ULP, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France); Rezig, B. [Laboratoire de Photovoltaique et Materiaux Semiconducteurs.(LPMS), Ecole Nationale d' ingenieurs de Tunis (ENIT), BP 37 le Belvedere 1002 Tunis (Tunisia)

    2009-02-02

    Within the chalcopyrite family the sulphur based compounds CuMS{sub 2} (M = In, Ga, Al) have attracted much interest in recent years because they show a direct wide band-gap covering from E{sub gap} = 1.53 eV (CuInS{sub 2}) over E{sub gap} = 2.43 eV (CuGaS{sub 2}) to E{sub gap} = 3.49 eV (CuAlS{sub 2}). Therefore they are particularly suitable for optoelectronic as well as photovoltaic applications. The CuAlS{sub 2} semiconductor is one of these compounds and has good luminescent properties and a wide direct gap of 3.5 eV making it suitable for the use as material for light-emitting devices in the blue region of the spectrum. To dig up fully its potential a better understanding of the fundamental properties of the CuAlS{sub 2} film itself is essential, which could be achieved from high-quality single-crystalline materials. So, the aim of this work has been to study the growth of multilayer CuAlS{sub 2} thin films on Si(111) substrates at a substrate temperature of 723 K. One, two and three layers with 60, 120 and 180 nm thicknesses, respectively, were deposited on Si(111) substrate. The effect of the CuAlS{sub 2} layer numbers on the structure, morphology and optical properties of the samples was investigated. The X-ray diffraction studies revealed that all the samples are polycrystalline in nature, single CuAlS{sub 2} phase and exhibiting chalcopyrite structure with a preferred orientation along the (112) direction. However, the sample with three CuAlS{sub 2} layers exhibit the highly oriented (112) plane with grain sizes of 80 nm. So we show that this experimental process affects significantly the structural properties of the CuAlS{sub 2} films. Raman spectroscopic measurements indicated five prominent peaks at 193, 205, 325, 335 and 370 cm{sup -1}. The possible origin of the 370 cm{sup -1} peak was investigated and was found to be some local vibration in the structure. The peaks at 193-205 and 335 cm{sup -1} were ascribed to A{sub 1} and B{sub 2} modes

  9. Study of the optical properties of CuAlS2 thin films prepared by two methods

    Science.gov (United States)

    Ahmad, S. M.

    2017-04-01

    CuAlS2 thin films were successfully deposited on glass substrates using two methods: chemical spray pyrolysis (CSP) and chemical bath deposition (CBD). It was confirmed from the X-ray diffraction (XRD) analysis that CSP films exhibited a polycrystalline nature while amorphous nature was diagnosed for CBD films. Also XRD analysis was utilized to compute grain size, strain and dislocation density. Surface morphology was characterized using scanning electron microscope and photomicroscope images. The optical absorption measurement revealed that the direct allowed electronic transition with band gaps 2.8 eV and 3.0 eV for CBD and CSP methods, respectively. The optical constants, such as extinction coefficient ( k), refractive index ( n), real and imaginary dielectric constants ( ɛ 1, ɛ 2) were discussed. The photoluminescence (PL) spectra of CuAlS2 thin films appeared as a single peak for each of them, and this is attributed to band-to-band transition.

  10. Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses

    Science.gov (United States)

    Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan

    2016-05-01

    Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.

  11. Preparation of highly oriented Al:ZnO and Cu/Al:ZnO thin films by sol-gel method and their characterization

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaprasath, G.; Murugan, R. [School of Physics, Alagappa University, Karaikudi 630 004, Tamil Nadu (India); Mahalingam, T. [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8011 (Japan); Ravi, G., E-mail: gravicrc@gmail.com [School of Physics, Alagappa University, Karaikudi 630 004, Tamil Nadu (India)

    2015-11-15

    Highly oriented thin films of Al doped ZnO (Al:ZnO) and Cu co-doped Al:ZnO (Cu/Al:ZnO) thin films were successfully deposited by sol–gel spin coating on glass substrates. The deposited films were characterized using X-ray diffraction analysis and found to exhibit hexagonal wurtzite structure with c-axis orientation. SEM images revealed that hexagonal rod shaped morphologies were grown perpendicular to the substrate surface due to repeated deposition process. High transmittance values were observed for pure ZnO compared to Al:ZnO and Cu/Al:ZnO thin films. The band gap widening is caused by the increase of carrier concentration, which is believed to be due to Burstein-Moss effect due to Al and Cu doping. PL spectra of Cu/Al:ZnO thin films indicate that the UV emission peaks slightly shifted towards lower energy side. XPS study was carried out for Zn{sub 0.80}Al{sub 0.10}Cu{sub 0.10}O thin films to analyze the binding energy of Al, Cu, Zn and O. Magnetic measurement studies exhibited ferromagnetic behavior at room temperature, which may be due to the increase in copper concentration in the doped films. The ferromagnetic behavior can be understood from the exchange coupling between localized ‘d’ spin of Cu ion mediated by free delocalized carriers. - Highlights: • High quality of Al:ZnO and Cu co-doped Al:ZnO thin films were fabricated by sol–gel method. • The XRD analyses revealed that the deposited thin films have hexagonal wurtzite structure. • XPS was carried out for Zn{sub 0.80}Al{sub 0.10}Cu{sub 0.10}O films to analyze the binding energy of Al, Cu, Zn and O. • SEM studies were made for Al:ZnO and Cu/Al:ZnO thin films. • RTFM was observed in Cu co-doped Al:ZnO thin films.

  12. Fabrication of CuAl1-xMxO2 (M = Fe, Cr)/Ni film delafossite compounds using spin coating and their microstructure and dielectric constant

    Science.gov (United States)

    Diantoro, Markus; Yuwita, Pelangi Eka; Olenka, Desyana; Nasikhudin

    2014-09-01

    The discovery of delafossite compound has encouraged more rapid technological developments particularly in transparent electronic devices. Copper oxide-based transparent thin films delafossite semiconductor recently give much attention in the field of optoelectronic technology, after the discovery of p-type CuAlO2. The potential applications of a p-type semiconductor transparent conductive oxides (TCO) have been applied in broad field of optoelectronics. To explore a broad physical properties interms of magnetic conducting subtitution is understudied. In this work we report the fabrication of delafossite film on Ni substrate and their characterization of CuAl1-xMxO2 delafossite compounds doped with Cr3+ and Fe3+ from the raw material of Cu(NO3)2˙3H2O, Al(NO3)3˙9H2O, Fe(NO3)3˙9H2O and Cr(NO3)3˙9H2O. The films were prepared using spin coating through a sol-gel technique at various concentrations of x = 0, 0.03, 0.04, and 0.05 for chromium and x = 0, 0.02, 0.04, 0.06, and 0.08 for iron doped. Crystal and microstructure were characterized by means of Cu-Kα Bragg-Brentano X-RD followed by High Score Plus and SEM-EDAX. The dielectric constants of the films were characterized using LCR meter. It was found that the CuAl1-xMxO2/Ni delafossite films were successfully fabricated. The CuAl1-xFexO2 compound crystallized with lattice parameters of a = b ranged from 2.8603 Å to 2.8675 Å and c ranged from 16.9576 to 17.0763 Å. The increase of the dopant give rise to the increase of the lattice parameters. Since iron has bigger ionic radius (69 pm) than original site of Al3+ with radius of 53 pm the crystal volume lattice also increase. Further analyses of increasing volume of the crystal, as expected, affected to the decreasing of its dielectric constant. The similar trends also shown by Cr3+ doped of CuAl1-xCrxO2 films with smaller effects.

  13. Oxygen diffusion in bilayer polymer films

    DEFF Research Database (Denmark)

    Poulsen, Lars; Zebger, Ingo; Tofte, Jannik Pentti;

    2004-01-01

    Experiments to quantify oxygen diffusion have been performed on polymer samples in which a film of poly(ethylene-co-norbornene) was cast onto a film of polystyrene which, in turn, was cast onto an oxygen-impermeable substrate. In the technique employed, the time evolution of oxygen transport...... through the film of poly(ethylene-co-norbornene) and into the polystyrene film was monitored using the phosphorescence of singlet oxygen as a spectroscopic probe. To analyze the data, it was necessary to solve Fick's second law of diffusion for both polymer films. Tractable analytical and numerical...... solutions were obtained for the problem. Moreover, the numerical solution is sufficiently general that it can be used to simulate oxygen concentration profiles in films consisting of more than two layers. Data obtained from the bilayer films yield a diffusion coefficient for oxygen in poly...

  14. /Cu-Al System

    Science.gov (United States)

    Kish, Orel; Froumin, Natalya; Aizenshtein, Michael; Frage, Nachum

    2014-05-01

    Wettability and interfacial interaction of the Ta2O5/Cu-Al system were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evaluation allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the final contact angle in the Ta2O5/Cu-Al system (50°) is determined by Ta adsorption on the newly formed alumina interlayer.

  15. Electronic and optical studies of pulse laser deposited ZnO/NiO bilayer film

    Science.gov (United States)

    Baraskar, P.; Dar, T. A.; Choudhary, R. J.; Sen, P. K.; Sen, P.

    2016-10-01

    We report the structural, optical and electronic properties of polycrystalline ZnO and NiO thin films and amorphous ZnO/NiO bilayer film, prepared by pulsed laser deposition technique. Despite of the presence of both Zn and Ni in +2 state in the bilayer film, the grown bilayer shows no reflections (in XRD) corresponding to ZnO or NiO. The difference in crystal structure of ZnO and NiO leads to the strain in the grown bilayer film. An increase in the band gap has been observed in bilayer film which can be attributed to the amorphous nature of the structure.

  16. Forming lipid bilayer membrane arrays on micropatterned polyelectrolyte film surfaces.

    Science.gov (United States)

    Zhang, Ying; Wang, Lei; Wang, Xuejing; Qi, Guodong; Han, Xiaojun

    2013-07-01

    A novel method of forming lipid bilayer membrane arrays on micropatterned polyelectrolyte film surfaces is introduced. Polyelectrolyte films were fabricated by the layer-by-layer technique on a silicon oxide surface modified with a 3-aminopropyltriethoxysilane (APTES) monolayer. The surface pK(a) value of the APTES monolayer was determined by cyclic voltammetry to be approximately 5.61, on the basis of which a pH value of 2.0 was chosen for layer-by-layer assembly. Micropatterned polyelectrolyte films were obtained by deep-UV (254 nm) photolysis though a mask. Absorbed fluorescent latex beads were used to visualize the patterned surfaces. Lipid bilayer arrays were fabricated on the micropatterned surfaces by immersing the patterned substrates into a solution containing egg phosphatidylcholine vesicles. Fluorescence recovery after photobleaching studies yielded a lateral diffusion coefficient for probe molecules of 1.31±0.17 μm(2) s(-1) in the bilayer region, and migration of the lipid NBD PE in bilayer lipid membrane arrays was observed in an electric field.

  17. Ultraviolet-induced erasable photochromism in bilayer metal oxide films

    Science.gov (United States)

    Terakado, Nobuaki; Tanaka, Keiji; Nakazawa, Akira

    2011-09-01

    We demonstrate that the optical transmittance of bilayer samples consisting of pyrolytically coated amorphous Mg-Sn-O and metal oxide films such as In 2O 3 and SnO 2 decreases upon ultraviolet illumination, but can be recovered by annealing in air at ˜300 ∘C. Spectral, structural, and compositional studies suggest that this photochromic phenomenon is induced by photoelectronic excitation in the Mg-Sn-O film, electron injection into the metal oxide, which becomes negatively charged, and subsequent formation of metallic particles, which absorb and/or scatter visible light.

  18. Study of annealing effects in Al–Sb bilayer thin films

    Indian Academy of Sciences (India)

    R K Mangal; B Tripathi; M Singh; Y K Vijay

    2007-02-01

    In this paper, we present preparation and characterization of Al–Sb bilayer thin films. Thin films of thicknesses, 3000/1000 Å and 3000/1500 Å, were obtained by the thermal evaporation (resistive heating) method. Vacuum annealing and rapid thermal annealing methods were used to mix bilayer thin film structure. Results obtained from optical band gap data and Rutherford back scattering spectrometry showed mixing of Al–Sb bilayer system.

  19. MARTENSITIC TRANSFORMATION AND THERMAL STABILITY IN Cu-Al-Co AND Cu-Al-Zr ALLOYS

    Institute of Scientific and Technical Information of China (English)

    Y. Q. Ma; C.B. Jiang; H.B. Xu

    2003-01-01

    Cu-Al-Co and Cu-Al-Zr alloys were explored with Co or Zr additions in Cu-Al alloys for high temperature shape memory alloys. Samples were quenched after homogenized at 850℃ for 48h. It was found that both Cu-Al-Co and Cu-Al-Zr show AlCu3 martensitic phase at room temperature and exhibit martensitic transformation temperatures higher than 200℃, showing the potentials for developing as high temperature shape memory alloys. Thermal cycles were performed by DSC instrument on both Cu-Al-Co and Cu-Al-Zr alloys. The results show that Cu-Al-Co loses its martensitic transformation after five thermal cycles, and Cu-Al-Zr exhibits no martensitic transformation in the second thermal cycle.

  20. Unexpected bilayer formation in Langmuir films of nucleolipids.

    Science.gov (United States)

    Desbat, Bernard; Arazam, Nessim; Khiati, Salim; Tonelli, Giovanni; Neri, Wilfrid; Barthélémy, Philippe; Navailles, Laurence

    2012-05-01

    Langmuir monolayers have been extensively investigated by various experimental techniques. These studies allowed an in-depth understanding of the molecular conformation in the layer, phase transitions, and the structure of the multilayer. As the monolayer is compressed and the surface pressure is increased beyond a critical value, usually occurring in the minimal closely packed molecular area, the monolayer fractures and/or folds, forming multilayers in a process referred to as collapse. Various mechanisms for monolayer collapse and the resulting reorganization of the film have been proposed, and only a few studies have demonstrated the formation of a bilayer after collapse and with the use of a Ca(2+) solution. In this work, Langmuir isotherms coupled with imaging ellipsometry and polarization modulation infrared reflection absorption spectroscopy were recorded to investigate the air-water interface properties of Langmuir films of anionic nucleolipids. We report for these new molecules the formation of a quasi-hexagonal packing of bilayer domains at a low compression rate, a singular behavior for lipids at the air-water interface that has not yet been documented.

  1. Alginate based bilayer hydrocolloid films as potential slow-release modern wound dressing.

    Science.gov (United States)

    Thu, Hnin-Ei; Zulfakar, Mohd Hanif; Ng, Shiow-Fern

    2012-09-15

    The aims of this research were to develop a novel bilayer hydrocolloid film based on alginate and to investigate its potential as slow-release wound healing vehicle. The bilayer is composed of an upper layer impregnated with model drug (ibuprofen) and a drug-free lower layer, which acted as a rate-controlling membrane. The thickness uniformity, solvent loss, moisture vapour transmission rate (MVTR), hydration rate, morphology, rheology, mechanical properties, in vitro drug release and in vivo wound healing profiles were investigated. A smooth bilayer film with two homogenous distinct layers was produced. The characterisation results showed that bilayer has superior mechanical and rheological properties than the single layer films. The bilayers also showed low MVTR, slower hydration rate and lower drug flux in vitro compared to single layer inferring that bilayer may be useful for treating low suppurating wounds and suitable for slow release application on wound surfaces. The bilayers also provided a significant higher healing rate in vivo, with well-formed epidermis with faster granulation tissue formation when compared to the controls. In conclusions, a novel alginate-based bilayer hydrocolloid film was developed and results suggested that they can be exploited as slow-release wound dressings.

  2. Combined effect of the transition layer and interfacial coupling on the properties of ferroelectric bilayer film

    Institute of Scientific and Technical Information of China (English)

    Sun Pu-Nan; Cui Lian; Lü Tian-Quan

    2009-01-01

    Within the framework of modified Ginzburg-Landau-Devonshire phenomenological theory,a ferroelectric bilayer film with a transition layer within each constituent film and an interfacial coupling between two materials has been studied.Properties including the Curie temperature and the spontaneous polarization of a bilayer film composed of two equally thick ferroelectric constituent films are discussed.The results show that the combined effect of the transition layer and the interfacial coupling plays an important role in explaining the interesting behaviour of ferroelectric multilayer structures consisting of two ferroelectric materials.

  3. Effect of annealing on the characteristics of Au/Ni50Fe50 bilayer films grown on glass

    Institute of Scientific and Technical Information of China (English)

    Hao Qian; Hong Qiu; Xiaobai Chen; Yue Tian; Ping Wu; Fengping Wang; Liqing Pan

    2007-01-01

    Sputter-deposited Au/Ni50Fe50 bilayer films were annealed in a vacuum of 5×10-4 Pa at 523 to 723 K for 30 or 90 min. The characteristics of the bilayer films were determined by Auger electron spectroscopy, field emission scanning electron microscopy, X-ray diffractometry, a four-point probe technique, and an alternating gradient magnetometer. When the annealing temperature and time reached 723 K and 90 min, Ni and Fe atoms markedly diffused into the Au layer. The grain size of the Au layer did not change markedly with the annealing condition. As the annealing time was 30 min and the annealing temperature exceeded 573 K, the resistance of the bilayer film increased with increasing the annealing temperature. Furthermore, the resistance of the bilayer film annealed at 723 K for 90 min was lower than that of the bilayer film annealed at 723 K for 30 min. All the bilayer films showed magnetic hysteresis loops. The as-deposited bilayer film showed a hard magnetization. The bilayer film represented an easy magnetization with increasing the annealing temperature. The Au/Ni50Fe50 film that annealed at 723 K for 90 min had the lowest saturation magnetization.

  4. Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Hu, Huimin [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 China (China)

    2017-04-15

    In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu{sub 2}(OH){sub 2}CO{sub 3}) and aluminum hydroxide (Al(OH){sub 3}) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

  5. Investigation of crystallization behavior of CIG-Se bi-layer thin films.

    Science.gov (United States)

    Park, Mi Sun; Sung, Shi-Joon; Kim, Dae-Hwan; Kang, Jin-Kyu

    2012-04-01

    Copper indium gallium diselenide (CIGSe) thin film was fabricated via a thermal treatment of GIG-Se bi-layer thin films. A CIG layer was prepared first, by a chemical solution deposition (CSD) process. The Se layer was deposited separately on the CIG layer by evaporation. The GIG-Se bi-layer then underwent a thermal treatment to cause a reaction between the two layers. In order to investigate the mechanism of CIG-Se bi-layer crystallization, the thermal treatment temperature was varied. The properties of the prepared CIGSe2 thin films were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometry (EDS), and UV-visible spectrophotometry.

  6. Raman Spectroscopy of DLC/a-Si Bilayer Film Prepared by Pulsed Filtered Cathodic Arc

    Directory of Open Access Journals (Sweden)

    C. Srisang

    2012-01-01

    Full Text Available DLC/a-Si bilayer film was deposited on germanium substrate. The a-Si layer, a seed layer, was firstly deposited on the substrate using DC magnetron sputtering and DLC layer was then deposited on the a-Si layer using pulsed filtered cathodic arc method. The bilayer films were deposited with different DLC/a-Si thickness ratios, including 2/2, 2/6, 4/4, 6/2, and 9/6. The effect of DLC/a-Si thickness ratios on the sp3 content of DLC was analyzed by Raman spectroscopy. The results show that a-Si layer has no effect on the structure of DLC film. Furthermore, the upper shift in G wavenumber and the decrease in ID/IG inform that sp3 content of the film is directly proportional to DLC thickness. The plot modified from the three-stage model informed that the structural characteristics of DLC/a-Si bilayer films are located close to the tetrahedral amorphous carbon. This information may be important for analyzing and developing bilayer protective films for future hard disk drive.

  7. Characteristics of Bilayer Molybdenum Films Deposited Using RF Sputtering for Back Contact of Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Sea-Fue Wang

    2014-01-01

    Full Text Available Mo films prepared under a single deposition condition seldom simultaneously obtain a low resistivity and a good adhesion necessary for use in solar cells. In order to surmount the obstacle, bilayer Mo films using DC sputtering at a higher working pressure and a lower working pressure have been attempted as reported in the literature. In this study, RF sputtering with different powers in conjunction with different working pressures was explored to prepare bilayer Mo film. The first bottom layer was grown at a RF sputtering power of 30 W and a working pressure of 12 mTorr, and the second top layer was deposited at 100 W and 4.5 mTorr. The films revealed a columnar growth with a preferred orientation along the (110 plane. The bilayer Mo films reported an electrical resistivity of 6.35 × 10−5 Ω-cm and passed the Scotch tape test for adhesion to the soda-lime glass substrate, thereby qualifying the bilayer Mo films for use as back metal contacts for CIGS substrates.

  8. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Science.gov (United States)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.

  9. Exchange coupling in MnBi/Fe-Co thin film bilayers

    Science.gov (United States)

    Fang, Lei; Gao, Tieren; Fackler, Sean; Maruyama, Shingo; Takeuchi, Ichiro; Cui, Jun; Krammer, M. J.; Johnson, Duane; Arenholz, Elke; Borchers, Julie; Kirby, Brian; Ratcliff, William; Skomski, Ralph; Lofland, Samuel

    2014-03-01

    To achieve enhanced energy products of MnBi for rare-earth free permanent magnet applications, we studied the exchange coupled soft/hard bilayers based on MnBi films. By using DC magnetron sputtering, we fabricated pure MnBi films with magnetization of 500 emu/cc and coercivity of 1.6 T. A (BH)max of 6.2 MGOe is obtained for pure MnBi films. A large enhancement in (BH)max due to exchange coupling in MnBi/Fe-Co bilayers is observed with Fe-Co thicknesses between 2 and 5 nm. The highest (BH)max obtained is 14.0 MGOe at room temperature with a single phase magnetization curve for a MnBi (20 nm)/Co (2 nm) bilayer. TEM and XPS studies indicate there is no oxidation between soft/hard interface. The XMCD results show that the soft moments of Fe/Co at a thickness of 2 nm are perpendicular to the MnBi plane, indicating nearly perfect hard-soft coupling. Moreover, a micromagnetic calculation on perpendicularly-coupled MnBi/Fe-Co bilayers suggests a critical coupling thickness of 4 nm of the soft layer. We will also discuss results from polarized neutron reflectometry measurements performed on the bilayers. This work is funded by ARPA-E.

  10. Microstructure and mechanical behavior of a shape memory Ni-Ti bi-layer thin film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Nili-Ahmadabadi, Mahmoud, E-mail: nili@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, University of Tehran, Tehran (Iran, Islamic Republic of); Ivanisenko, Julia [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Schwaiger, Ruth [Karlsruhe Institute of Technology, Institute for Applied Materials, 76021 Karlsruhe (Germany); Hahn, Horst; Chakravadhanula, Venkata Sai Kiran [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany)

    2015-05-29

    Two different single-layers and a bi-layer Ni-Ti thin films with chemical compositions of Ni{sub 45}Ti{sub 50}Cu{sub 5}, Ni{sub 50.8}Ti{sub 49.2} and Ni{sub 50.8}Ti{sub 49.2}/Ni{sub 45}Ti{sub 50}Cu{sub 5} (numbers indicate at.%) determined by energy dispersive X-ray spectroscopy were deposited on Si (111) substrates using DC magnetron sputtering. The structures, surface morphology and transformation temperatures of annealed thin films at 500 °C for 15 min and 1 h were studied using grazing incidence X-ray diffraction, transmission electron microscopy (TEM), atomic force microscopy and differential scanning calorimetry (DSC), respectively. Nanoindentation was used to characterize the mechanical properties. The DSC and X-ray diffraction results indicated the austenitic structure of the Ni{sub 50.8}Ti{sub 49.2} and martensitic structure of the Ni{sub 45}Ti{sub 50}Cu{sub 5} thin films while the bi-layer was composed of austenitic and martensitic thin films. TEM study revealed that copper encourages crystallization in the bi-layer such that crystal structure containing nano-precipitates in the Ni{sub 45}Ti{sub 50}Cu{sub 5} layer was detected after 15 min annealing while the Ni{sub 50.8}Ti{sub 49.2} layer crystallized after 60 min at 500 °C. Furthermore, after annealing at 500 °C for 15 min, a precipitate free zone and thin layer amorphous were observed closely to the interface in the top layer. The bi-layer was completely crystallized at 500 °C for 1 h and the orientation of the Ni-rich precipitates indicated a stress gradient in the bi-layer. The bi-layer thin film showed different transformation temperatures and mechanical behavior from the single-layers. The developed bi-layer has different phase transformation temperatures, the higher temperatures of shape memory effect and lower temperature of pseudo-elastic behavior compared to the single-layers. Also, the bi-layer thin film exhibited a combined pseudo-elastic behavior and shape memory effect with a reduced

  11. Coupling effects in bilayer thick metal films perforated with rectangular nanohole arrays

    Directory of Open Access Journals (Sweden)

    Li Yuan

    2013-09-01

    Full Text Available The coupling effects in bilayer thick metal (silver films perforated with rectangular nanohole arrays are investigated using the finite-difference time-domain technique. Many interesting light phenomena are observed as the distance between the metal rectangular nanohole arrays varies. Coupling effects are found to play very important roles on the optical and electronic properties of bilayer metal rectangular nanohole arrays: antisymmetric coupling between surface plasmon polaritons near the top and bottom film plane, and antisymmetric coupling between localized surface plasmon resonances near the two long sides of the rectangular hole, are probably excited in each layer of bilayer metal rectangular nanohole arrays; antisymmetric and symmetric magnetic coupling probably occur between the metal rectangular nanohole arrays.

  12. MAGNETIC EXCHANGE-COUPLING IN CoPt/Co BILAYER THIN FILMS

    Energy Technology Data Exchange (ETDEWEB)

    KIM,J.; BARMAK,K.; LEWIS,L.H.; CREW,D.C.; WELCH,D.O.

    1999-04-05

    Thin film CoPt/Co bilayers have been prepared as a model system to investigate the relationship between microstructure and exchange coupling in two-phase hard/soft composite magnets. CoPt films, with a thickness of 25 nm, were sputter-deposited from a nearly equiatomic alloy target onto oxidized Si wafers. The films were subsequently annealed at 700 C and fully transformed from the FCC phase to the magnetically hard, ordered L1{sub 0} phase. The coercivity of the films increased rapidly with annealing time until it reached a plateau at approximately 9.5 kOe. Fully-ordered CoPt films were then used as substrates for deposition of Co layers, with thicknesses in the range of 2.8--225 nm, in order to produce the hard/soft composite bilayers. As predicted by theory, the magnetic coherency between the soft Co phase and the hard, ordered CoPt phase decreased as the thickness of the soft phase increased. This decrease in coupling was clearly seen in the magnetic hysteresis loops of the bilayers. At small thicknesses of Co (a few nanometers), the shape of the loop was one of a uniform material showing no indication of the presence of two phases with extremely different coercivities. At larger Co thicknesses, constricted loops, i.e., ones showing the presence of a mixture of two ferromagnetic phases of different hardnesses, were obtained. The magnetic exchange present in the bilayer samples was qualitatively analyzed using magnetic recoil curves and the dependence of exchange coupling on the soft phase dimension in the bilayer hard/soft composite magnet films is discussed.

  13. Nanocrystals formation and fractal microstructural assessment in Au/Ge bilayer films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.W. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)]. E-mail: cnzwchen@yahoo.com.cn; Lai, J.K.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Shek, C.H. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Chen, H.D. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)

    2005-08-31

    Nanocrystals formation and fractal microstructural assessment in Au/Ge bilayer films upon annealing have been investigated by transmission electron microscopy and high-resolution transmission electron microscopy observations. Experimental results indicated that the microstructure of the metal Au film plays an important role in metal-induced crystallization for Au/Ge bilayer films upon annealing. Synchronously, the crystallization processes of amorphous Ge accompanied by the formation of Ge fractal clusters, which were composed of Ge nanocrystals. We found that the grain boundaries of polycrystalline Au film were the initial nucleation sites of Ge nanocrystals. High-resolution transmission electron microscopy observations showed successive nucleation of amorphous Ge at Au grain boundaries near fractal tips. The crystallization process was suggested to be diffusion controlled and a random successive nucleation and growth mechanism.

  14. Synthesis and Electrochemical Behavior of Ceria Based Bi-Layer Films by Dip Coating Technique.

    Science.gov (United States)

    Chinnu, M Karl; Anand, K Vijai; Kumar, R Mohan; Alagesan, T; Jayavel, R

    2015-01-01

    Ceria based bi-layer films of CeO2-CdS and CeO2-TiO2 were prepared by sol-gel based hydrothermal route combined with dip-coating. The synthesized samples were subjected to various characterizations such as X-ray diffraction, Field emission scanning electron microscopy, thermo-gravimetric analysis, UV-Vis absorption and photoluminescence studies. The prepared materials were dissolved in naffion solution and disposed as a thin film on glassy carbon electrode by dip coating technique. Electrochemical Li+ intercalation/deintercalation was performed by cyclic voltammetry and these results indicate that the CeO2/LiClO4 system is electrochemically reversible. The total intercalation/deintercalation of the CeO2 film, CeO2-CdS and CeO2-TiO2 bi-layer films was determined by cyclic voltammetry, which showed increased charge storage capacity.

  15. Electrochemomechanical Behaviour of Bilayer and Trilayer Films with PEDOT and PPY Conducting Polymers

    DEFF Research Database (Denmark)

    Zainudeen, Umer L.; Careem, M.A.; Skaarup, Steen

    2008-01-01

    a constant load of 1.5 g. The cyclic voltammograms as well as the UV-visible spectra of PEDOT and PPy are very different, pointing towards the possibility of being able to separate the two layers experimentally – even when combined in a single film. Bilayer results show combined characteristics of each...

  16. Electrochemomechanical Behaviour of Bilayer and Trilayer Films with PEDOT and PPY Conducting Polymers

    DEFF Research Database (Denmark)

    Zainudeen, Umer L.; Careem, M.A.; Skaarup, Steen

    2008-01-01

    a constant load of 1.5 g. The cyclic voltammograms as well as the UV-visible spectra of PEDOT and PPy are very different, pointing towards the possibility of being able to separate the two layers experimentally – even when combined in a single film. Bilayer results show combined characteristics of each...

  17. Synthesis of Cu-Al-Zn-O nanocomposite: effect of annealing on the physical properties

    Indian Academy of Sciences (India)

    Laya Dejam; Seyed Mohammad Elahi; Majid Mojtahedzade Larijani; Yousef Seyed Jalili

    2015-12-01

    We prepared Cu-Al-Zn-O (CAZO) nanocomposite thin films on quartz substrates by radio frequency (RF) magnetron sputtering method. The as-deposited CAZO film is amorphous in nature and annealing in air environment results in weak crystallization of the films and formation of CuAlO2 and CAZO. The surface morphology of the films was studied with atomic force microscopy images, while Rutherford backscattering spectrometry (RBS) was used to characterize material properties. The optical bandgap of films was found to be 3–4.2 eV depending on the annealing temperature. The photoluminescence (PL) of the samples was measured at room temperature. Violet, blue and green spectra peaks were observed from the PL spectra of the four samples. The emission spectrum indicates the suitability of CAZO nanocomposite for gas sensor applications and technology.

  18. Enhanced Piezoelectric Energy Harvesting Performance of Flexible PVDF-TrFE Bilayer Films with Graphene Oxide.

    Science.gov (United States)

    Bhavanasi, Venkateswarlu; Kumar, Vipin; Parida, Kaushik; Wang, Jiangxin; Lee, Pooi See

    2016-01-13

    Ferroelectric materials have attracted interest in recent years due to their application in energy harvesting owing to its piezoelectric nature. Ferroelectric polymers are flexible and can sustain larger strains compared to inorganic counterparts, making them attractive for harvesting energy from mechanical vibrations. Herein, we report, for the first time, the enhanced piezoelectric energy harvesting performance of the bilayer films of poled poly(vinylidene fluoride-trifluoroethylene) [PVDF-TrFE] and graphene oxide (GO). The bilayer film exhibits superior energy harvesting performance with a voltage output of 4 V and power output of 4.41 μWcm(-2) compared to poled PVDF-TrFE films alone (voltage output of 1.9 V and power output of 1.77 μWcm(-2)). The enhanced voltage and power output in the presence of GO film is due to the combined effect of electrostatic contribution from graphene oxide, residual tensile stress, enhanced Young's modulus of the bilayer films, and the presence of space charge at the interface of the PVDF-TrFE and GO films, arising from the uncompensated polarization of PVDF-TrFE. Higher Young's modulus and dielectric constant of GO led to the efficient transfer of mechanical and electrical energy.

  19. Silicon induced stability and mobility of indium zinc oxide based bilayer thin film transistors

    Science.gov (United States)

    Chauhan, Ram Narayan; Tiwari, Nidhi; Liu, Po-Tsun; Shieh, Han-Ping D.; Kumar, Jitendra

    2016-11-01

    Indium zinc oxide (IZO), silicon containing IZO, and IZO/IZO:Si bilayer thin films have been prepared by dual radio frequency magnetron sputtering on glass and SiO2/Si substrates for studying their chemical compositions and electrical characteristics in order to ascertain reliability for thin film transistor (TFT) applications. An attempt is therefore made here to fabricate single IZO and IZO/IZO:Si bilayer TFTs to study the effect of film thickness, silicon incorporation, and bilayer active channel on device performance and negative bias illumination stress (NBIS) stability. TFTs with increasing single active IZO layer thickness exhibit decrease in carrier mobility but steady improvement in NBIS; the best values being μFE ˜ 27.0, 22.0 cm2/Vs and ΔVth ˜ -13.00, -6.75 V for a channel thickness of 7 and 27 nm, respectively. While silicon incorporation is shown to reduce the mobility somewhat, it raises the stability markedly (ΔVth ˜ -1.20 V). Further, IZO (7 nm)/IZO:Si (27 nm) bilayer based TFTs display useful characteristics (field effect mobility, μFE = 15.3 cm2/Vs and NBIS value, ΔVth =-0.75 V) for their application in transparent electronics.

  20. Study of annealing effects in In–Sb bilayer thin films

    Indian Academy of Sciences (India)

    R K Mangal; Y K Vijay

    2007-04-01

    The thin films of In–Sb having different thicknesses of antimony keeping constant thickness of indium was deposited by thermal evaporation method on ITO coated conducting glass substrates at room temperature and a pressure of 10-5 torr. The samples were annealed for 1 h at 433 K at a pressure of 10-5 torr. The optical transmission spectra of as deposited and annealed films have been carried out at room temperature. The variation in optical band gap with thickness was also observed. Rutherford back scattering and X-ray diffraction analysis confirms mixing of bilayer system. The transverse – characteristic shows mixing effect after annealing at 433 K for 1 h. This study confirms mixing of bilayer structure of semiconductor thin films.

  1. Brillouin light scattering study of spin waves in NiFe/Co exchange spring bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Haldar, Arabinda; Banerjee, Chandrima; Laha, Pinaki; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata 700098 (India)

    2014-04-07

    Spin waves are investigated in Permalloy(Ni{sub 80}Fe{sub 20})/Cobalt(Co) exchange spring bilayer thin films using Brillouin light scattering (BLS) experiment. The magnetic hysteresis loops measured by magneto-optical Kerr effect show a monotonic decrease in coercivity of the bilayer films with increasing Py thickness. BLS study shows two distinct modes, which are modelled as Damon-Eshbach and perpendicular standing wave modes. Linewidths of the frequency peaks are found to increase significantly with decreasing Py layer thickness. Interfacial roughness causes to fluctuate exchange coupling at the nanoscale regimes and the effect is stronger for thinner Py films. A quantitative analysis of the magnon linewidths shows the presence of strong local exchange coupling field which is much larger compared to macroscopic exchange field.

  2. Crystallization study of amorphous sputtered NiTi bi-layer thin film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam, E-mail: mmohri@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany); Nili-Ahmadabadi, Mahmoud [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, University of Tehran, Tehran (Iran, Islamic Republic of); Chakravadhanula, Venkata Sai Kiran [Karlsruhe Institute of Technology, Institute of Nanotechnology, 76021 Karlsruhe (Germany)

    2015-05-15

    The crystallization of Ni-rich/NiTiCu bi-layer thin film deposited by magnetron sputtering from two separate alloy targets was investigated. To achieve the shape memory effect, the NiTi thin films deposited at room temperature with amorphous structure were annealed at 773 K for 15, 30, and 60 min for crystallization. Characterization of the films was carried out by differential scanning calorimetry to indicate the crystallization temperature, grazing incidence X-ray diffraction to identify the phase structures, atomic force microscopy to evaluate surface morphology, scanning transmission electron microscopy to study the cross section of the thin films. The results show that the structure of the annealed thin films strongly depends on the temperature and time of the annealing. Crystalline grains nucleated first at the surface and then grew inward to form columnar grains. Furthermore, the crystallization behavior was markedly affected by composition variations. - Highlights: • A developed bi-layer Ni45TiCu5/Ni50.8Ti was deposited on Si substrate and crystallized. • During crystallization, The Ni{sub 45}TiCu{sub 5} layer is thermally less stable than the Ni-rich layer. • The activation energy is 302 and 464 kJ/mol for Cu-rich and Ni-rich layer in bi-layer, respectively.

  3. Structural modifications to enhance the exciton diffusion in bilayer porphyrin fullerene thin films

    Science.gov (United States)

    Kaushal, Meesha; Srinivasamurthy, Praveen; Walter, Michael G.

    2016-09-01

    The effects of peripheral alkyl groups and thermal annealing on the exciton quenching efficiency in bilayer porphyrinfullerene thin films has been investigated. The thin film UV-vis absorbance spectra, steady-state fluorescence emission, and thermal properties of three carboalkoxyphenyl porphyrin derivatives have been studied: tetra(4-carbohexoxyphenyl)porphyrin (TCH4PP), tetra(4-carbo-2-ethylhexoxyphenyl)porphyrin (TCEH4PP), and tetra(4-carbooctoxyphenyl)-porphyrin (TCO4PP). The quenching efficiencies of these three derivatives have been calculated from their steady-state emission using pristine spin cast films and films with an evaporated C60 bilayer. Structural analyses have been performed using X-ray diffraction (XRD), UV-vis spectroscopy, and thermal properties were studied using differential scanning calorimetry measurements (DSC). Annealing the films caused significant structural changes as was observed in the UV-vis absorbance spectra and XRD diffraction patterns. Prior to thermal annealing, quenching efficiencies are greatest for the TCH4PP and TCO4PP (hexyl and octyl derivatives), which is in agreement with previous bulk quenching experiments to calculate exciton diffusion lengths.1 After annealing, the hexyl derivative (TCH4PP) showed the lowest bilayer quenching efficiency and indicated evidence of significant molecular rearrangements.

  4. Monolayer and bilayer structures in ionic liquids and their mixtures confined to nano-films.

    Science.gov (United States)

    Smith, Alexander M; Lovelock, Kevin R J; Perkin, Susan

    2013-01-01

    The confinement of liquids to thin films can lead to dramatic changes in their structural arrangement and dynamic properties. Ionic liquids display nano-structures in the bulk of the liquid, consisting of polar and non-polar domains, whereas a solid surface can induce layered structures in the near-surface liquid. Here we compare and contrast the layer structures in a series of imidazolium and pyrrolidinium-based ionic liquids upon confinement of the liquids to films of approximately 0-20 nm between two negatively charged mica surfaces. Using a surface force balance (SFB) we measured the force between the two atomically smooth mica surfaces with ionic liquid between, directly revealing the ion packing and dimensions of layered structures for each liquid. The ionic liquids with shorter alkyl chain substituents form alternating cation-anion monolayer structures on confinement, whilst a longer alkyl chain leads to alignment of the cations in bilayer formation. The crossover from monolayers to bilayers, however, occurs at different alkyl chain lengths for imidazolium- and pyrrolidinium-based ionic liquids with a common anion. In addition, we find that imidazolium cation bilayers are arranged in toe-to-toe orientation, whereas pyrrolidinium cations form bilayers consisting of fully interdigitated alkyl chains. Results for a mixture of monolayer-preferring (i.e. short alkyl chain) and bilayer-preferring (i.e. long alkyl chain) liquids indicate alkyl chain segregation and bilayer-like structures. We discuss the driving forces for these self-assembly effects, and the contrasting behaviour of the imidazolium and pyrrolidinium-type ionic liquids.

  5. Bi-layer functionally gradient thick film semiconducting methane sensors

    Indian Academy of Sciences (India)

    A Banerjee; A K Haldar; J Mondal; A Sen; H S Maiti

    2002-11-01

    Gas sensors based on metal oxide semiconductors like tin dioxide are widely used for the detection of toxic and combustible gases like carbon monoxide, methane and LPG. One of the problems of such sensors is their lack of sensitivity, which to some extent, can be circumvented by using different catalysts. However, highly reactive volatile organic compounds (VOC) coming from different industrial and domestic products (e.g. paints, lacquers, varnishes etc) can play havoc on such sensors and can give rise to false alarms. Any attempt to adsorb such VOCs (e.g. by using activated charcoal) results in sorption of the detecting gases (e.g. methane) too. To get round the problem, bi-layer sensors have been developed. Such tin oxide based functionally gradient bi-layer sensors have different compositions at the top and bottom layers. Here, instead of adsorbing the VOCs, they are allowed to interact and are consumed on the top layer of the sensors and a combustible gas like methane being less reactive, penetrates the top layer and interacts with the bottom layer. By modifying the chemical compositions of the top and bottom layers and by designing the electrode-lead wire arrangement properly, the top layer can be kept electrically shunted from the bottom layer and the electrical signal generated at the bottom layer from the combustible gas is collected. Such functionally gradient sensors, being very reliable, can find applications in domestic, industrial and strategic sectors.

  6. Controlling the alloy composition of PtNi nanocrystals using solid-state dewetting of bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Okkyun; Oh, Se An; Lee, Ji Yeon; Ha, Sung Soo; Kim, Jae Myung; Choi, Jung Won; Kim, Jin-Woo [Department of Physics and Photon Science & School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005 (Korea, Republic of); Kang, Hyon Chol [Department of Materials and Science Engineering, Chosun University, Gwangju 61542 (Korea, Republic of); Noh, Do Young, E-mail: dynoh@gist.ac.kr [Department of Physics and Photon Science & School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005 (Korea, Republic of)

    2016-05-15

    We demonstrate that solid-state dewetting of bilayer films is an effective way for obtaining bimetallic alloy nanocrystals of controlled composition. When a Pt–Ni bilayer film were annealed near 700 °C, Pt and Ni atoms inter-diffused to form a PtNi bimetallic alloy film. Upon annealing at higher temperatures, the bilayer films transformed into <111> oriented PtNi alloy nanocrystals in small-rhombicuboctahedron shape through solid-state dewetting process. The Pt content of the nanocrystals and the alloy films, estimated by applying the Vegard's law to the relaxed lattice constant, was closely related to the thickness of each layer in the as-grown bilayer films which can be readily controlled during bilayer deposition. - Highlights: • Composition control of PtNi nanoparticles using solid state dewetting is proposed. • PtNi alloy composition was controlled by thickness ratio of Pt–Ni bilayer films. • PtNi alloy nanocrystals were obtained in small-rhombicuboctahedron shape.

  7. Shape-alterable and -recoverable graphene/polyurethane bi-layered composite film for supercapacitor electrode

    Science.gov (United States)

    Tai, Zhixin; Yan, Xingbin; Xue, Qunji

    2012-09-01

    In this paper, a graphene/shape-memory polyurethane (PU) composite film, used for a supercapacitor electrode, is fabricated by a simple bonding method. In the composite, formerly prepared graphene paper is closely bonded on the surface of the PU slice, forming a bi-layered composite film. Based on the good flexibility of graphene paper and the outstanding shape holding capacity of PU phase, the resulting composite film can be changed into various shapes. Also, the composite film shows excellent shape recovery ability. The graphene/PU composite film used as the electrode maintains a satisfactory electrochemical capacitance of graphene material and there is no decay in the specific capacitance after long-cycle testing, making it attractive for novel supercapacitors with special shapes and shape-memory ability.

  8. Electric polarization in bi-layered ferromagnetic film with combined magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Gareeva, Z.V., E-mail: gzv@anrb.ru [Institute of Molecule and Crystal Physics, Academy of Sciences, 151, prospect Octobrya, Ufa 450075 (Russian Federation); Doroshenko, R.A. [Institute of Molecule and Crystal Physics, Academy of Sciences, 151, prospect Octobrya, Ufa 450075 (Russian Federation); Mazhitova, F.A. [Bashkir State University, 32 Z. Validi str., Ufa 450076 (Russian Federation); Shulga, N.V. [Institute of Molecule and Crystal Physics, Academy of Sciences, 151, prospect Octobrya, Ufa 450075 (Russian Federation)

    2015-07-01

    Magnetoelectric phenomena become one of the most attractive fields of magnetism. One of discussable items is inhomogeneous magnetoelectricity leading to appearance of electric polarization of magnetic domain walls, improper polarization of multiferroics etc. In our article we attract attention to the modulation of electric polarization by magnetic inhomogeneity in exchange coupled ferromagnetic film whose layers differ by magnetic anisotropy. Our goal is to explore the influence of combined magnetic anisotropy (especially its cubic component) on the behavior of electric polarization of bi-layered film placed in magnetic field. We perform theoretical analysis in a frame of phenomenological modeling of spins structures considering two geometries of magnetic field (magnetic field oriented perpendicular to a film plane and magnetic field oriented in a film plane along “hard magnetization” axis). Our results show that the presence of cubic magnetic anisotropy (K{sub c}<0) in the layers allocates the planes of magnetic inhomogeneities and correspondingly the directions of electric polarization. We demonstrate that magnetic field applied along the “hard magnetization” axis leads to the rotation of electric polarization in the 45° range and magnetic field applied along normal to a film influences the magnitude of electric polarization leading to the lowering of polarization after attaining the maximum value. - Highlights: • Magnetic inhomogeneity in bi-layered ferromagnetic film generates electric polarization. • Cubic magnetic anisotropy allocates the direction of electric polarization. • Magnetic field applied along “hard magnetization” axis rotates electric polarization.

  9. Bilayered Films Based on Novel Polymer Derivative for Improved Ocular Therapy of Gatifloxacin

    Directory of Open Access Journals (Sweden)

    Naval Dinesh Aher

    2014-01-01

    Full Text Available Context. Thiomers could prove to be suitable mucoadhesives for fabrication of ocular inserts. Objective. The study intends to explore the application of thiolated sodium alginate (TSA to the preparation of bilayered ocular inserts of gatifloxacin. Methods. Cysteine moieties were grafted onto sodium alginate (SA and the resultant thiomer was characterized for relevant physicochemical properties. Bilayered inserts were fabricated with a mucoadhesive immediate release layer composed of either SA or TSA and a sustained release layer composed of acrylates. Films were prepared by solvent evaporation and evaluated for mechanical properties, drug content, and in vitro release. Results and Discussion. The synthesized TSA possessed 248.80±49.7 μmol thiol groups/gm and its solutions thickened on standing due to disulphide bridging. Its films showed improved mucoadhesion and also a strikingly beneficial property of resisting erosion and remaining as a hydrated adhesive layer for the duration of drug release. The bilayered films were found to be flexible, with good folding endurance, uniform thickness, and appropriate drug content, and showed a release of about 80% of loaded gatifloxacin in 12 h. Conclusion. The study demonstrates promise in employing thiolated polymer in conjunction with acrylates for the design of ocular inserts for twice a day therapy with gatifloxacin.

  10. P-type Cu2O/SnO bilayer thin film transistors processed at low temperatures

    KAUST Repository

    Al-Jawhari, Hala A.

    2013-10-09

    P-type Cu2O/SnO bilayer thin film transistors (TFTs) with tunable performance were fabricated using room temperature sputtered copper and tin oxides. Using Cu2O film as capping layer on top of a SnO film to control its stoichiometry, we have optimized the performance of the resulting bilayer transistor. A transistor with 10 nm/15 nm Cu2O to SnO thickness ratio (25 nm total thickness) showed the best performance using a maximum process temperature of 170 C. The bilayer transistor exhibited p-type behavior with field-effect mobility, on-to-off current ratio, and threshold voltage of 0.66 cm2 V-1 s-1, 1.5×10 2, and -5.2 V, respectively. The advantages of the bilayer structure relative to single layer transistor are discussed. © 2013 American Chemical Society.

  11. Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression.

    Science.gov (United States)

    Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro

    2016-08-13

    This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu68Al16Zn16 (CuAlZn) and Cu73Al15Mn12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s(-1) (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (ΔTad) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hysteresis at each strain were compared. The stress at the maximum recoverable strain of 4.0% for CuAlMn was 120 MPa, which is 70% smaller than that of CuAlZn. A smaller hysteresis for the CuAlMn alloy was also obtained, about 70% less compared with the CuAlZn alloy. The latent heat, determined by differential scanning calorimetry, was 4.3 J g(-1) for the CuAlZn alloy and 5.0 J g(-1) for the CuAlMn alloy. Potential coefficients of performance (COPmat) for these two alloys were calculated based on their physical properties of measured latent heat and hysteresis, and a COPmat of approximately 13.3 for CuAlMn was obtained.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.

  12. Optical and water repellant properties of Ag/SnO2 bilayer thin films

    Directory of Open Access Journals (Sweden)

    Ravipati Praveena

    2016-02-01

    Full Text Available The optical and water repellant properties of single layer and bilayer films of Ag and SnO2 deposited on glass substrates by thermal evaporation have been reported. Ag/SnO2 bilayers were deposited in two sequences wherein the deposition of SnO2 layer was followed by Ag deposition and vice versa. X-ray diffraction studies show that the Ag films crystallize in the FCC structure and SnO2 is amorphous, while atomic force microscopy images indicate the formation of large clusters of the order of 12 nm. The single layer Ag films exhibit localized surface plasmon resonance (LSPR that shifts from visible region to the infrared with increase in thickness from 5 to 12 nm. It is observed that, only the Ag films of thickness ≤ 8 nm exhibits LSPR peak whereas the critical thickness is 5 nm for Ag/SnO2 films. A blue shift is observed in the LSPR peak position when the SnO2 layer caps the Ag film. Whereas, the LSPR of Ag is suppressed significantly when the SnO2 layer is introduced between the glass and the Ag film and also when Ag and SnO2 were co-evaporated. Water repellant properties indicate that the pure Ag film has an average contact angle of 104o which decreases to 100o when SnO2 caps the Ag layer and 97o when Ag is deposited on top of the SnO2 buffer layer. Co-evaporated Ag-SnO2 films show a contact angle of 93o.

  13. Synthesis of mono- and bi-layer MFI zeolite films on macroporous alumina tubular supports: Application to nanofiltration

    Science.gov (United States)

    Said, Ali; Limousy, Lionel; Nouali, Habiba; Michelin, Laure; Halawani, Jalal; Toufaily, Joumana; Hamieh, Tayssir; Dutournié, Patrick; Daou, T. Jean

    2015-10-01

    This work is dedicated to the development of MFI-type structure zeolite films (single-layer or bilayer) on the internal layer of a specific macroporous alumina tubular support for nanofiltration applications. The bottom MFI layer was obtained by direct hydrothermal synthesis while a secondary growth method was used for the top MFI layer. A complete characterization of the obtained MFI membranes (single-layer or bilayer) is proposed using various techniques, such as X-ray diffraction, scanning electron microscopy, mercury porosimetry and nitrogen sorption measurements. Dense and highly crystallized films of MFI-type structure zeolite were obtained for both single-layer and bilayer MFI films. The total film thickness were around 7.1±0.5 μm and 14.5±1 μm for single-layer and bilayer MFI films respectively. The Si/Al molar ratio of the MFI films varied between 185 and 305 for single-layer and bilayer MFI films respectively. The hydraulic permeability of the tubular MFI membrane was achieved by the filtration of pure water. The hydraulic permeability of the single-layer and bilayer MFI membranes decreased rapidly at the beginning of the conditioning process, and stabilized at 1.08×10-14 m3 m-2 and 1.02×10-15 m3 m-2 after 15 h and the rejection rates of neutral solute (Vb 12) are 10% and 50% for the single-layer and bilayer MFI films respectively.

  14. Giant electrocaloric effect in PZT bilayer thin films by utilizing the electric field engineering

    Science.gov (United States)

    Zhang, Tiandong; Li, Weili; Cao, Wenping; Hou, Yafei; Yu, Yang; Fei, Weidong

    2016-04-01

    The enhancement of the electrocaloric effect (ECE) was achieved by the amplifying effect of applied electric field through devising the thin films' structure. The PbZr0.95Ti0.05O3/PbZr0.52Ti0.48O3 bilayer structured thin films were fabricated on a Pt(111)/Ti/SiO2/Si substrate using sol-gel method. The ΔS = 20.5 J K-1 kg-1 and ΔT = 24.8 K for bilayer thin films is achieved around 125 °C much below Tc, which is caused by the amplifying electric field induced phase transition of OAFE/RFE in PZr0.95Ti0.05O3 layer. It is also worth mentioning that the films exhibit outstanding ECE at room temperature; ΔS = 11.9 J K-1 kg-1 and ΔT = 10.7 K are observed, which are attributed to the effect of amplifying electric field in PbZr0.95Ti0.05O3 layer and RFE/TFE at morphotropic phase boundaries (MPB) in PbZr0.52Ti0.48O3 layer. This result indicates that to amplify the local electric field engineering and to maximize the number of coexisting phases in heterostructures or multilayer thin films may be an effective way for cooling applications.

  15. SnO2/TiO2 bilayer thin films exhibiting superhydrophilic properties

    Science.gov (United States)

    Talinungsang, Nibedita Paul; Purkayastha, Debarun Dhar

    2017-05-01

    Nanostructured thin films of TiO2, SnO2, and SnO2/TiO2 have been deposited by sol-gel method. The films are characterized by X-ray diffraction, wettability and optical properties. In the present work, we have achieved a way of converting hydrophilic to super-hydrophilic state by incorporating TiO2 buffer layer in between substrate and SnO2 film, which has its utility in anti-fogging surfaces. The decrease in contact angle of water over SnO2/TiO2 bilayer is attributed to the increase in roughness of the film as well as surface energy of the substrate.

  16. Thickness dependencies of structural and magnetic properties of cubic and tetragonal Heusler alloy bilayer films

    Science.gov (United States)

    Ranjbar, R.; Suzuki, K. Z.; Sugihara, A.; Ando, Y.; Miyazaki, T.; Mizukami, S.

    2017-07-01

    The thickness dependencies of the structural and magnetic properties for bilayers of cubic Co-based Heusler alloys (CCHAs: Co2FeAl (CFA), Co2FeSi (CFS), Co2MnAl (CMA), and Co2MnSi (CMS)) and D022-MnGa were investigated. Epitaxy of the B2 structure of CCHAs on a MnGa film was achieved; the smallest thickness with the B2 structure was found for 3-nm-thick CMS and CFS. The interfacial exchange coupling (Jex) was antiferromagnetic (AFM) for all of the CCHAs/MnGa bilayers except for unannealed CFA/MnGa samples. A critical thickness (tcrit) at which perpendicular magnetization appears of approximately 4-10 nm for the CMA/MnGa and CMS/MnGa bilayers was observed, whereas this thickness was 1-3 nm for the CFA/MnGa and CFS/MnGa films. The critical thickness for different CCHAs materials is discussed in terms of saturation magnetization (Ms) and the Jex .

  17. Enhanced photoactivity in bilayer films with buried rutile-anatase heterojunctions.

    Science.gov (United States)

    Romero-Gomez, Pablo; Borras, Ana; Barranco, Angel; Espinos, Juan P; Gonzalez-Elipe, Agustin R

    2011-01-17

    Herein, we study the photoactivity of anatase-rutile bilayer thin films consisting of an anatase overlayer of variable thickness from some tenths to some hundred nanometers deposited onto a rutile thin film. As references single anatase layers of equivalent thickness were deposited onto silicon. All the films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. The photoactivity of the samples was assessed by following the evolution with the UV illumination time of both the wetting angle on the thin film surface and the decoloration of a dye in a water solution. While a similar efficiency is found for the first type of experiments irrespective of the anatase thickness, in the second type a maximum in the photoactivity is found for a thickness of the anatase layer of about 130 nm. This enhanced photoactivity in bilayer systems with a buried anatase-rutile heterojunction is related to the formation of different Schottky potential barriers in the anatase layer, depending on its thickness and the substrate (i.e. rutile or SiO(2)) where it is deposited.

  18. Active Bilayer PE/PCL Films for Food Packaging Modified with Zinc Oxide and Casein

    Directory of Open Access Journals (Sweden)

    Ana Rešček

    2015-12-01

    Full Text Available This paper studies the properties of active polymer food packaging bilayer polyethylene/polycaprolactone (PE/PCL films. Such packaging material consists of primary PE layer coated with thin film of PCL coating modified with active component (zinc oxide or zinc oxide/casein complex with intention to extend the shelf life of food and to maintain the quality and health safety. The influence of additives as active components on barrier, mechanical, thermal and antimicrobial properties of such materials was studied. The results show that, in comparison to the neat PE and PE/PCL films, some of PE/PCL bilayer films with additives exhibit improved barrier properties i.e. decreased water vapour permeability. Higher thermal stability of modified PE/PCL material is obtained due to a modified mechanism of thermal degradation. The samples with the additive nanoparticles homogeneously dispersed in the polymer matrix showed good mechanical properties. Addition of higher ZnO content contributes to the enhanced antibacterial activity of a material.

  19. Enhanced ZnO Thin-Film Transistor Performance Using Bilayer Gate Dielectrics

    KAUST Repository

    Alshammari, Fwzah H.

    2016-08-24

    We report ZnO TFTs using Al2O3/Ta2O5 bilayer gate dielectrics grown by atomic layer deposition. The saturation mobility of single layer Ta2O5 dielectric TFT was 0.1 cm2 V-1 s-1, but increased to 13.3 cm2 V-1 s-1 using Al2O3/Ta2O5 bilayer dielectric with significantly lower leakage current and hysteresis. We show that point defects present in ZnO film, particularly VZn, are the main reason for the poor TFT performance with single layer dielectric, although interfacial roughness scattering effects cannot be ruled out. Our approach combines the high dielectric constant of Ta2O5 and the excellent Al2O3/ZnO interface quality, resulting in improved device performance. © 2016 American Chemical Society.

  20. PEALD YSZ-based bilayer electrolyte for thin film-solid oxide fuel cells

    Science.gov (United States)

    Yu, Wonjong; Cho, Gu Young; Hong, Soonwook; Lee, Yeageun; Kim, Young Beom; An, Jihwan; Cha, Suk Won

    2016-10-01

    Yttria-stabilized zirconia (YSZ) thin film electrolyte deposited by plasma enhanced atomic layer deposition (PEALD) was investigated. PEALD YSZ-based bi-layered thin film electrolyte was employed for thin film solid oxide fuel cells on nanoporous anodic aluminum oxide substrates, whose electrochemical performance was compared to the cell with sputtered YSZ-based electrolyte. The cell with PEALD YSZ electrolyte showed higher open circuit voltage (OCV) of 1.0 V and peak power density of 182 mW cm-2 at 450 °C compared to the one with sputtered YSZ electrolyte(0.88 V(OCV), 70 mW cm-2(peak power density)). High OCV and high power density of the cell with PEALD YSZ-based electrolyte is due to the reduction in ohmic and activation losses as well as the gas and electrical current tightness.

  1. Antireflective bilayer coatings based on Al2O3 film for UV region

    OpenAIRE

    Marszałek Konstanty; Winkowski Paweł; Marszałek Marta

    2015-01-01

    Bilayer antireflective coatings consisting of aluminium oxide Al2O3/MgF2 and Al2O3/SiO2 are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5 × 10-3 Pa in the presence of oxygen, and magnesium fluoride was prepared by thermal evaporation on heated optical lenses made from quartz glass (Corning HPFS). Substrate temperature was maintained at 250 _C during the deposition. Thickness and deposition rate were controlled with a thickness measuring syste...

  2. The variation of linewidth in exchange coupled bilayer films with stress anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei [Inner Mongolia Key Lab of Nanoscience and Nanotechnology and School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021 (China); Rong, Jianhong, E-mail: jhrong502@163.com [Inner Mongolia Key Lab of Nanoscience and Nanotechnology and School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021 (China); Yun, Guohong, E-mail: ndghyun@imu.edu.cn [Inner Mongolia Key Lab of Nanoscience and Nanotechnology and School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021 (China); College of Physics and Electronic Information, Inner Mongolia Normal University, Hohhot 010022 (China); Wang, Dong; Bao, Lingbo [Inner Mongolia Key Lab of Nanoscience and Nanotechnology and School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021 (China)

    2016-12-01

    The frequency linewidth and the field linewidth in ferromagnetic/antiferromagnetic bilayer films with stress anisotropy have been investigated by using ferromagnetic resonance method. The effects of the stress anisotropy for in-plane anisotropy, weak and strong perpendicular anisotropy on linewidth are observed. It is found that the frequency and the field linewidth all increase for in-plane and weak perpendicular anisotropy, as the stress anisotropy field increases. And furthermore, the stress anisotropy field affects obviously the frequency and the field linewidth for unsaturation field.

  3. Antireflective bilayer coatings based on Al2O3 film for UV region

    OpenAIRE

    Marszałek Konstanty; Winkowski Paweł; Marszałek Marta

    2015-01-01

    Bilayer antireflective coatings consisting of aluminium oxide Al2O3/MgF2 and Al2O3/SiO2 are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5 × 10-3 Pa in the presence of oxygen, and magnesium fluoride was prepared by thermal evaporation on heated optical lenses made from quartz glass (Corning HPFS). Substrate temperature was maintained at 250 _C during the deposition. Thickness and deposition rate were controlled with a thickness measuring syste...

  4. Thin-film silica sol-gels doped with ion responsive fluorescent lipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, D.Y.; Shea, L.E.; Sinclair, M.B.

    1999-01-12

    A metal ion sensitive, fluorescent lipid-b i layer material (5oA PSIDA/DSPC) was successfully immobilized in a silica matrix using a tetramethoxysilane (TMOS) sol-gel procedure. The sol-gel immobilization method was quantitative in the entrapment of seif-assembled Iipid-bilayers and yielded thin films for facile configuration to optical fiber piatforms. The silica matrix was compatible with the solvent sensitive lipid bilayers and provided physical stabilization as well as biological protection. Immobilization in the silica sol-gel produced an added benefit of improving the bilayer's metal ion sensitivity by up to two orders of magnitude. This enhanced performance was attributed to a preconcentrator effect from the anionic surface of the silica matrix. Thin gels (193 micron thickness) were coupled to a bifurcated fiber optic bundle to produce a metal ion sensor probe. Response times of 10 - 15 minutes to 0.1 M CUCIZ were realized with complete regeneration of the sensor using an ethylenediarninetetraacetic acid (EDTA) solution.

  5. Third-order optical nonlinearity studies of bilayer Au/Ag metallic films

    Science.gov (United States)

    Mezher, M. H.; Chong, W. Y.; Zakaria, R.

    2016-05-01

    This paper presents nonlinear optical studies of bilayer metallic films of gold (Au) and silver (Ag) on glass substrate prepared using electron beam evaporation. The preparation of Au and Ag nanoparticles (NPs) on the substrate involved the use of electron beam deposition, then thermal annealing at 600 °C and 270 °C, respectively, to produce a randomly distributed layer of Au and a layer of Ag NPs. Observation of field-effect scanning electron microscope images indicated the size of the NPs. Details of the optical properties related to peak absorption of surface plasmon resonance of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear absorption and nonlinear refraction of the fabricated NP layers. The third-order nonlinear refractive index coefficients for Au and Ag are (-9.34 and  -1.61)  ×  10-11 cm2 W-1 given lower n 2, in comparison with bilayer (Au and Ag) NPs at  -1.24  ×  10-10 cm2 W-1. The results show bilayer NPs have higher refractive index coefficients thus enhance the nonlinearity effects.

  6. Strongly compressed Bi (111) bilayer films on Bi{sub 2}Se{sub 3} studied by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, K. F.; Yang, Fang; Song, Y. R. [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Canhua; Qian, Dong; Gao, C. L.; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093 (China)

    2015-09-21

    Ultra-thin Bi films show exotic electronic structure and novel quantum effects, especially the widely studied Bi (111) film. Using reflection high-energy electron diffraction and scanning tunneling microscopy, we studied the structure and morphology evolution of Bi (111) thin films grown on Bi{sub 2}Se{sub 3}. A strongly compressed, but quickly released in-plane lattice of Bi (111) is found in the first three bilayers. The first bilayer of Bi shows a fractal growth mode with flat surface, while the second and third bilayer show a periodic buckling due to the strong compression of the in-plane lattice. The lattice slowly changes to its bulk value with further deposition of Bi.

  7. Transparent Conductive Al-Doped ZnO/Cu Bilayer Films Grown on Polymer Substrates at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    黄继杰; 王钰萍; 吕建国; 龚丽; 叶志镇

    2011-01-01

    Al-doped ZnO (AZO)/Cu bi-layer films are deposited by dc magnetron sputtering on polycarbonate substrates at room temperature. The structural, electrical and optical properties of the films are investigated at various sputtering powers of the Cu layer. The AZO/Cu bi-layer film deposited at a moderate sputtering power of 180 W for the Cu layer displayed the highest figure of merit of 3.47 x 10~3 Ω-1, with a low sheet resistance of12.38Ω/sq, an acceptable visible transmittance of 73%, and a high near-infrared reflectance of about 50%.%Al-doped ZnO(AZO)/Cu bi-layer films are deposited by dc magnetron sputtering on polycarbonate substrates at room temperature.The structural,electrical and optical properties of the films are investigated at various sputtering powers of the Cu layer.The AZO/Cu bi-layer film deposited at a moderate sputtering power of 180 W for the Cu layer displayed the highest figure of merit of 3.47 × 10-3 Ω-1,with a low sheet resistance of 12.38Ω/sq,an acceptable visible transmittance of 73%,and a high near-infrared reflectance of about 50%.

  8. X-ray reflectivity investigation of the foam bilayer film formed by hexaethylene glycol dodecyl ether

    Institute of Scientific and Technical Information of China (English)

    SHEN Qiang; J. J. Benattar; LI Xin; LIU Shaojie

    2003-01-01

    Structural parameters for the free-standing foam film of hexaethylene glycol monododecyl ether (C12E6) have been measured by using X-ray reflectometry. The results indicate that a "five-laminae" model corresponds to this inverted bilayer and divides it into five regions. The thicknesses of the aliphatic chainregions, the polar head-group regions, and the central aqueous core are 0.90, 1.35 and 1.31 nm, respectively; and their corresponding electron densities are 2.4 ( 10?3, 2.6 ( 10?3 and 2.3(10?3 electron/nm3, respectively; the interfacial roughness between adjacent regions is 0.34 nm. The central core of this foam film does not contain free water, its thickness decreased 0.40 nm under the irradiation of infrared rays due to the loss of structural water.

  9. Correlation of Magnetic Properties of Co/Cr Bilayer Thin Films with Grain Boundary Diffusion

    Institute of Scientific and Technical Information of China (English)

    Gaowu Qin; Bo Yang; Wenli Pei; Yuping Ren

    2009-01-01

    The microstructure and magnetic properties of Co/Cr bilayer films were examined before and after post-deposition annealing by using transmission electron microscopy (TEM), X-ray diffraction (XRD) technique and vibrating sample magnetometer (VSM). A model of grain boundary (GB) Cr-rich phase growth involving GB diffusion derived from the Cr underlayer was proposed to elucidate the kinetics of the paramagnetic Cr-rich phase growth along Co GBs within the Co layer. The correlation of the GB Cr-rich phase formation with the magnetic Co grain isolation and accordingly, improvement of magnetic properties was experimentally investigated and discussed in detail. Our analysis results are well consistent with previous micromagnetic simulations on the improvement of magnetic properties by the magnetic grain isolation. The results provide some insights into the processing-structure-property relationships of the Co/Cr bilayer films, and thus suggest that the magnetic grain isolation be feasible not only in longitudinal recording media, but also be effective in tuning the exchange coupling of magnetic grains in perpendicular recording media via the GB diffusion from underlayer and/or overlayer.

  10. Tuning the nanostructure of DODAB/nickel tetrasulfonated phthalocyanine bilayers in LbL films.

    Science.gov (United States)

    Furini, L N; Feitosa, E; Alessio, P; Shimabukuro, M H; Riul, A; Constantino, C J L

    2013-07-01

    Nanostructured films of dioctadecyldimethylammonium bromide (DODAB) and nickel tetrasulfonated phthalocyanine (NiTsPc) were layer-by-layer (LbL) assembled to achieve a synergistic effect considering the distinct properties of both materials. Prior to LbL growth, the effect of NiTsPc on the structure of DODAB vesicles in aqueous medium was investigated by differential scanning calorimetry (DSC). Therefore, DODAB/NiTsPc LbL films were prepared using NiTsPc at concentrations below and above the limit concentration of vesicle formation according to our DSC experiments. As a result, LbL films with distinct nanostructures were obtained, which were studied at micro and nanoscales by micro-Raman and atomic force microscopy, respectively. A linear growth of the LbL films was observed by ultraviolet-visible absorption spectroscopy. However, the bilayer thickness and the surface morphology of the LbL films were radically affected depending on NiTsPc concentration. The electrostatic interaction between DODAB and NiTsPc was identified via Fourier transform infrared (FTIR) absorption spectroscopy as the main driving force responsible for LbL growth. Because LbL films have been widely applied as transducers in sensing devices, DODAB/NiTsPc LbL films having distinct nanostructures were tested as proof-of-principle in preliminary sensing experiments toward dopamine detection using impedance spectroscopy (e-tongue system). The real capacitance vs. dopamine concentration curves were treated using Principal Component Analysis (PCA) and an equivalent electric circuit, revealing the role played by the LbL film nanostructure and the possibility of building calibration curves.

  11. Tuning the nanostructure of DODAB/nickel tetrasulfonated phthalocyanine bilayers in LbL films

    Energy Technology Data Exchange (ETDEWEB)

    Furini, L.N. [Faculdade de Ciências e Tecnologia, UNESP Univ Estadual Paulista, Presidente Prudente, SP (Brazil); Feitosa, E. [Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas,UNESP Univ Estadual Paulista, São José do Rio Preto, SP (Brazil); Alessio, P.; Shimabukuro, M.H. [Faculdade de Ciências e Tecnologia, UNESP Univ Estadual Paulista, Presidente Prudente, SP (Brazil); Riul, A. [Universidade Federal de São Carlos, campus Sorocaba, Sorocaba, SP (Brazil); Constantino, C.J.L., E-mail: case@fct.unesp.br [Faculdade de Ciências e Tecnologia, UNESP Univ Estadual Paulista, Presidente Prudente, SP (Brazil)

    2013-07-01

    Nanostructured films of dioctadecyldimethylammonium bromide (DODAB) and nickel tetrasulfonated phthalocyanine (NiTsPc) were layer-by-layer (LbL) assembled to achieve a synergistic effect considering the distinct properties of both materials. Prior to LbL growth, the effect of NiTsPc on the structure of DODAB vesicles in aqueous medium was investigated by differential scanning calorimetry (DSC). Therefore, DODAB/NiTsPc LbL films were prepared using NiTsPc at concentrations below and above the limit concentration of vesicle formation according to our DSC experiments. As a result, LbL films with distinct nanostructures were obtained, which were studied at micro and nanoscales by micro-Raman and atomic force microscopy, respectively. A linear growth of the LbL films was observed by ultraviolet–visible absorption spectroscopy. However, the bilayer thickness and the surface morphology of the LbL films were radically affected depending on NiTsPc concentration. The electrostatic interaction between DODAB and NiTsPc was identified via Fourier transform infrared (FTIR) absorption spectroscopy as the main driving force responsible for LbL growth. Because LbL films have been widely applied as transducers in sensing devices, DODAB/NiTsPc LbL films having distinct nanostructures were tested as proof-of-principle in preliminary sensing experiments toward dopamine detection using impedance spectroscopy (e-tongue system). The real capacitance vs. dopamine concentration curves were treated using Principal Component Analysis (PCA) and an equivalent electric circuit, revealing the role played by the LbL film nanostructure and the possibility of building calibration curves. - Highlights: • Changes in thermogram profile reflect the way NiTsPc affects DODAB vesicle structure. • The growth of LbL film is driven by electrostatic interactions between DODAB and NiTsPc. • The nanostructure of the LbL films is determined by NiTsPc concentration. • Lower NiTsPc concentrations lead to

  12. Structural and superconducting properties of ion beam sputtered Nb thin films and Nb/Cu bilayers

    Science.gov (United States)

    Nath, S. K.; Dhawan, R.; Rai, S.; Lodha, G. S.; Sokhey, K. J. S.

    2012-01-01

    We present the results of a study of structural and superconducting properties of polycrystalline Nb thin films (200 Å, 300 Å, 400 Å, 700 Å and 1000 Å) and Nb/Cu bilayers (300 Å/300 Å and 400 Å/300 Å) prepared on Si substrates by ion beam sputtering at room temperature. The thicknesses, roughnesses at the surfaces and interfaces were determined by X-ray reflectivity whereas the grain sizes were determined from grazing incidence X-ray diffraction and transmission electron microscopic studies. The superconducting transition temperature ( T C) of Nb thin films are smaller than T C of bulk Nb. The Nb-200 Å sample does not show T C down to 2.3 K. The average size of the grains varies from 42 Å for Nb-200 Å sample to 69 Å for Nb-1000 Å sample. Our results show that the T C in these polycrystalline films is not only limited by its thickness but also by the size of the grains. The Nb films deposited in situ on the Cu layer (Nb/Cu) show a marginal increase in average sizes of the grains as compare to their respective values in Nb films of same thicknesses. As a result a marginal increase in T C of these films is also observed. The maximum decrease in T C due to oxygen intake during deposition should be about 0.5 K from its bulk value (9.28 K). We have attributed the large decrease in T C in our case on the basis of decrease in the Debye temperature and density of states at the Fermi level for Nb thin films as compared to their respective values for bulk Nb.

  13. Temperature-induced assembly of semiconductor nanocrystals into fractal architectures and thermoelectric power properties in Au/Ge bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Li Quanbao; Wang Jian; Jiao Zheng [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Wu Minghong, E-mail: mhwu@staff.shu.edu.cn [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Shek, Chan-Hung; Lawrence Wu, C.M.; Lai, Joseph K.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Chen Zhiwen, E-mail: cnzwchen@yahoo.com.cn [Shanghai Applied Radiation Institute, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

    2011-08-15

    Highlights: > Ge fractal architectures were achieved by temperature-induced assembly. > The appearance of fractal architectures influences the thermoelectric power. > But it has little effect on the resistivity. > The values of the superlocalization exponent were within 1.22 {<=} {xi} {<=} 1.29. > It was higher than expected for two-dimension fractal system. - Abstract: Fractal architectures of semiconductor nanocrystals were successfully achieved by temperature-induced assembly of semiconductor nanocrystals in gold/germanium (Au/Ge) bilayer films. New assessment strategies of fractal architectures are of fundamental importance in the development of micro/nano-devices. Temperature-dependent properties including resistivity and thermoelectric power (TEP) of Au/Ge bilayer films with self-similar fractal patterns were investigated in detail. Experimental results indicated that the microstructure of Au film plays an important role in the characteristics of Au/Ge bilayer films after annealing and the crystallization processes of amorphous Ge accompany by fractal formation of Ge nanocrystals via temperature-induced assembly. The appearance of fractal architectures has significantly influence on the TEP but little effect on the resistivity of the annealed bilayer film. By analysis of the data, we found that the values of superlocalization exponent are within 1.22 {<=} {xi} {<=} 1.29, which are higher than expected for two-dimension fractal systems. The results provided possible evidence for the superlocalization on fractal architectures in Au/Ge bilayer films. The TEP measurements are considered a more effective method than the conductivity for investigating superlocalization in a percolating system.

  14. Microstructural characterization, optical and photocatalytic properties of bilayered CuO and ZnO based thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Pizá-Ruiz, P.; Solís-Canto, O.; Ornelas-Gutiérrez, C.; Pérez-García, S.; Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx

    2014-12-05

    Highlights: • High quality bilayered Zn–Cu oxide thin films were deposited by aerosol assisted CVD. • Detailed microstructural characterization was performed by XRD and electron microscopy. • Absorbance of bilayered films shows a shift of absorption edge toward visible region. • Optical band gap or nearly 3.2 and 2 eV was determined for ZnO and Cu oxide. • High photocatalytic activity around 90% was obtained for bilayered samples. - Abstract: In this work, it is presented the synthesis, microstructural characterization and photocatalytic properties of bilayered CuO–ZnO/ZnO thin films onto borosilicate glass and fused silica substrates. The films were deposited by aerosol assisted chemical vapor deposition, using an experimental setup reported elsewhere. Deposition conditions were optimized to get high quality films; i.e. they were structurally uniform, highly transparent, non-light scattering, homogeneous, and well adhered to the substrate. Different Cu/Zn atomic ratios were tried for the upper layer. The microstructure of the films was characterized by grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy. GIXRD results indicate the presence of ZnO Wurzite and Cu oxide phases. Results of SEM and HRTEM analysis of the cross sectional microstructure showed that the films were composed of compact and dense layers with no visible evidence of an interfacial boundary or porosity. Optical absorbance of the bilayered films showed a clear shift of the absorption toward the visible range. Optical band gap was determined roughly at 3.2 and 2 eV for ZnO and Cu oxide, respectively. Photocatalytic activity of the samples, for the degradation of a 10{sup −5} mol dm{sup −3} solution of methylene blue (MB), was determined after 120 and 240 min of irradiation with an UV-A source. Around 90% of MB degradation was reached by bilayered films with

  15. Third order elastic constants of bcc Cu-Al-Ni

    OpenAIRE

    Gonzàlez Comas, Alfons; Mañosa, Lluís

    1996-01-01

    We have measured the changes in the ultrasonic wave velocity, induced by the application of uniaxial stresses in a Cu-Al-Ni single crystal. From these measurements, the complete set of third-order elastic constants has been obtained. The comparison of results for Cu-Al-Ni with available data for other Cu-based alloys has shown that all these alloys exhibit similar anharmonic behavior. By using the measured elastic constants in a Landau expansion for elastic phase transitions, we have been abl...

  16. Microstructural and chemical transformation of thin Ti/Pd and TiDy/Pd bilayer films induced by vacuum annealing.

    Science.gov (United States)

    Lisowski, W; Keim, E G; Kaszkur, Z; van den Berg, A H J; Smithers, M A

    2007-11-01

    Using a combination of scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction and X-ray photoelectron spectroscopy (XPS), we made a comparative study of the high-temperature annealing impact on thin titanium deuteride (TiD(y)) films covered by an ultrathin Pd layer, and on Ti/Pd bilayer films. The bilayer films were prepared under ultrahigh vacuum conditions and were in situ annealed using the same annealing procedure. It was found that the surface and the bulk morphology of both films undergo different annealing-induced transformations, leading to an extensive intermixing between the Ti and Pd layers and the formation of a new PdTi(2) bimetallic phase. Energy-filtered TEM imaging and energy-dispersive X-ray spectrometry analysis, as well as XPS depth profiling all provided evidence of a different distribution of Pd and Ti in the annealed TiD(y)/Pd film compared with the annealed Ti/Pd film. Our results show that thermal decomposition of TiD(y), as a consequence of annealing the TiD(y)/Pd film, modifies the intermixing process, thereby promoting Ti diffusion into the Pd-rich top layer of the TiD(y) film and thus providing a more likely path for the formation of the PdTi(2) phase than in an annealed Ti/Pd film.

  17. Interaction Effects in SmCo/FeCo Bilayer Film Media

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The magnetic property of Sm22Co78/Fe65Co35 bilayer film media prepared by magnetron sputtering was measured. All the samples have in-plane anisotropy and the hysteresis loops are simple single loops, indicating that the two phases are strongly exchange-coupled. The reduced remanence (Mr/Ms) was found to increase from 0.58 to 0.8 with increasing Fe65Co35 layer thickness (d) for a fixed Sm22Co78 layer thickness. The coercivity was found to increase with increasing a few Fe65Co35 layer, and then to decrease with continuously increasing Fe65Cos5 layer. The intergranular exchange and magnetostatic interaction effects were measured from their remanence magnetization curves.

  18. Raman spectra of bilayer graphene covered with Poly(methyl methacrylate thin film

    Directory of Open Access Journals (Sweden)

    Minggang Xia

    2012-09-01

    Full Text Available The Raman spectra of bilayer graphene covered with poly(methyl methacrylate (PMMA were investigated. Both the G and 2D peaks of PMMA-coated graphene were stiff and broad compared with those of uncovered graphene. This could be attributed to the residual strain induced by high-temperature baking during fabrication of the nanodevice. Furthermore, the two 2D peaks stiffened and broadened with increasing laser power, which is just the reverse to uncovered graphene. The stiffness is likely caused by graphene compression induced by the circular bubble of the thin PMMA film generated by laser irradiation. Our findings may contribute to the application of PMMA in the strain engineering of graphene nanodevices.

  19. Analysis of wide color gamut of green/red bilayered freestanding phosphor film-capped white LEDs for LCD backlight.

    Science.gov (United States)

    Oh, Ji Hye; Kang, Heejoon; Ko, Minji; Do, Young Rag

    2015-07-27

    In this study, we propose green/red bilayered freestanding phosphor film-capped white light-emitting diodes (W-LEDs) using InGaN blue LEDs and narrowband red and green phosphors to realize a wide color gamut in a liquid crystal display (LCD) backlight system. The narrowband K2SiF6:Mn4+ (KSF) red and SrGa2S4:Eu2+ (SGS) green phosphors are synthesized using a facile etching synthetic process and flux-aided solid state reaction under a H2S atmosphere, respectively, and the freestanding phosphor films are fabricated using a delamination method with water-soluble polymer, polystyrene sulfonic acid, PEDOT/PSS, and interlayered phosphor film. Various phosphor concentrations of green/red bilayered freestanding phosphor film-capped W-LEDs exhibit a correlated color temperature (CCT) and luminous efficacy range of 11,390 K ~6,540 K and 99 lm/W ~124 lm/W, respectively, with an applied current of 60 mA. The W-LED with green (12.5 wt%)/red (40 wt%) bilayered phosphor film, which exhibited luminous efficacy of 105 lm/W at the CCT of 8,330 K, is selected and the color gamut of the bare LED and phosphor RG and the filtered RGB triangle is calculated to be more than ~95% and ~86.4%, respectively, relative to the NTSC in the 1931 CIE color coordinates space.

  20. Fabrication of bilayered YSZ/SDC electrolyte film by electrophoretic deposition for reduced-temperature operating anode-supported SOFC

    Science.gov (United States)

    Matsuda, Motohide; Hosomi, Takushi; Murata, Kenji; Fukui, Takehisa; Miyake, Michihiro

    Bilayered Y 2O 3-stabilized ZrO 2 (YSZ)/Sm 2O 3-doped CeO 2 (SDC) electrolyte films were successfully fabricated on porous NiO-YSZ composite substrates by electrophoretic deposition (EPD) based on electrophoretic filtration followed by co-firing with the substrates. In EPD, positively charged YSZ and SDC powders were deposited directly on the substrates, layer by layer from ethanol-based suspensions. Delamination between YSZ and SDC films was avoided by reducing the SDC films' thickness to ca. 1 μm. A single cell was constructed on the bilayered electrolyte films composed of ca. 4 μm-thick YSZ and ca. 1 μm-thick SDC films. As a cathode in the cell, La 0.6Sr 0.4Co 0.2Fe 0.8O 3- x (LSCF) was used. Maximum output power densities greater than 0.6 W cm -2 were obtained at 700 °C for the bilayered YSZ/SDC electrolyte cells thus constructed.

  1. Fabrication of bilayered YSZ/SDC electrolyte film by electrophoretic deposition for reduced-temperature operating anode-supported SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Motohide; Hosomi, Takushi; Miyake, Michihiro [Graduate School of Environmental Science, Okayama University, 3-1-1 Tsushima-Naka, Okayama 700-8530 (Japan); Murata, Kenji; Fukui, Takehisa [Hosowaka Powder Technology Research Institute, 1-9 Shoudai, Tajika, Hirakata, Osaka 573-1132 (Japan)

    2007-02-25

    Bilayered Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} (YSZ)/Sm{sub 2}O{sub 3}-doped CeO{sub 2} (SDC) electrolyte films were successfully fabricated on porous NiO-YSZ composite substrates by electrophoretic deposition (EPD) based on electrophoretic filtration followed by co-firing with the substrates. In EPD, positively charged YSZ and SDC powders were deposited directly on the substrates, layer by layer from ethanol-based suspensions. Delamination between YSZ and SDC films was avoided by reducing the SDC films' thickness to ca. 1 {mu}m. A single cell was constructed on the bilayered electrolyte films composed of ca. 4 {mu}m-thick YSZ and ca. 1 {mu}m-thick SDC films. As a cathode in the cell, La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-x} (LSCF) was used. Maximum output power densities greater than 0.6 W cm{sup -2} were obtained at 700 C for the bilayered YSZ/SDC electrolyte cells thus constructed. (author)

  2. Development and in vitro assessment of alginate bilayer films containing the olive compound hydroxytyrosol as an alternative for topical chemotherapy.

    Science.gov (United States)

    Ng, Shiow-Fern; Tan, Say-Lee

    2015-11-30

    Topical chemotherapy is the application of cancer drugs directly onto the skin, which has become a standard treatment for basal cell carcinoma. Due to the promising results in the treatment of skin cancer, topical chemotherapy has recently been applied to breast cancer patients because some breast cancer tissues are only superficial. Hydroxytyrosol, a phenolic compound from olives that is present in high amounts in Hidrox(®) olive extract, has been shown to have a protective effect on normal cells and selective antitumor activities on cancerous cells. The aims of the present study were to develop an alginate bilayer film containing Hidrox(®) and to investigate its potential use as a topical chemotherapeutic agent. Alginate films were characterized for swelling and for physical, thermal, rheological, and mechanical properties. Drug content uniformity and in vitro drug release tests were also investigated. The alginate bilayer films containing Hidrox(®), HB2, showed controlled release of hydroxytyrosol at a flux of 0.094±0.009 mg/cm(2)/h. The results of the cytotoxic assay showed that the HB2 films were dose-dependent and could significantly reduce the growth of breast cancer cells (MCF-7) at 150 μg/mL for a cell viability of 29.34±4.64%. In conclusion, an alginate bilayer film containing Hidrox(®) can be a potential alternative for topical chemotherapeutic agent for skin and breast cancer treatment.

  3. Poole-Frenkel effect in sputter-deposited CuAlO(2+x) nanocrystals.

    Science.gov (United States)

    Banerjee, Arghya Narayan; Joo, Sang Woo

    2013-04-26

    Field-assisted thermionic emission within a sputter-deposited, nanocrystalline thin film of CuAlO2.06 is observed for the first time, and explained in terms of the Poole-Frenkel model. The presence of adsorbed oxygen ions as trap-states at the grain boundary regions of the nanostructured thin film is considered to manifest this phenomenon. Under an applied field, the barrier of the trap potential is lowered and thermal emission of charge carriers takes place at different sample temperatures to induce nonlinearity in the current (I)-voltage (V) characteristics of the nanomaterial. Fitting of the Poole-Frenkel model with the I-V data shows that the nonlinearity is effective above 50 V under the operating conditions. Calculations of the energy of the trap level, acceptor level and Fermi level reveal the existence of deep level trap-states and a shallow acceptor level with acceptor concentration considerably higher than the trap-states. Hall measurements confirm the p-type semiconductivity of the film, with a hole concentration around 10(18) cm(-3). Thermopower measurements give a room-temperature Seebeck coefficient around 130 μV K(-1). This temperature-dependent conductivity enhancement within CuAlO2 nanomaterial may find interesting applications in transparent electronics and high-voltage applications for power supply networks.

  4. Bi-layer Channel AZO/ZnO Thin Film Transistors Fabricated by Atomic Layer Deposition Technique.

    Science.gov (United States)

    Li, Huijin; Han, Dedong; Liu, Liqiao; Dong, Junchen; Cui, Guodong; Zhang, Shengdong; Zhang, Xing; Wang, Yi

    2017-12-01

    This letter demonstrates bi-layer channel Al-doped ZnO/ZnO thin film transistors (AZO/ZnO TFTs) via atomic layer deposition process at a relatively low temperature. The effects of annealing in oxygen atmosphere at different temperatures have also been investigated. The ALD bi-layer channel AZO/ZnO TFTs annealed in dry O2 at 300 °C exhibit a low leakage current of 2.5 × 10(-13)A, I on/I off ratio of 1.4 × 10(7), subthreshold swing (SS) of 0.23 V/decade, and high transmittance. The enhanced performance obtained from the bi-layer channel AZO/ZnO TFT devices is explained by the inserted AZO front channel layer playing the role of the mobility booster.

  5. Bi-layer Channel AZO/ZnO Thin Film Transistors Fabricated by Atomic Layer Deposition Technique

    Science.gov (United States)

    Li, Huijin; Han, Dedong; Liu, Liqiao; Dong, Junchen; Cui, Guodong; Zhang, Shengdong; Zhang, Xing; Wang, Yi

    2017-03-01

    This letter demonstrates bi-layer channel Al-doped ZnO/ZnO thin film transistors (AZO/ZnO TFTs) via atomic layer deposition process at a relatively low temperature. The effects of annealing in oxygen atmosphere at different temperatures have also been investigated. The ALD bi-layer channel AZO/ZnO TFTs annealed in dry O2 at 300 °C exhibit a low leakage current of 2.5 × 10-13A, I on/ I off ratio of 1.4 × 107, subthreshold swing (SS) of 0.23 V/decade, and high transmittance. The enhanced performance obtained from the bi-layer channel AZO/ZnO TFT devices is explained by the inserted AZO front channel layer playing the role of the mobility booster.

  6. [Effect of microwaves on bilayer lipid membranes: role of a membrane-forming hole in the Teflon film].

    Science.gov (United States)

    Alekseev, S I; Ziskin, M S; Fesenko, E E

    2009-01-01

    The distributions of specific abcorption rate (SAR) and E-field in a membrane-forming hole of Teflon film and surrounding electrolyte were calculated for 0.9 GHz exposure. It was found that the specific absorption rate in the membrane-forming hole increased greatly with increasing thickness of the Teflon film, and electrolyte concentration and decreasing diameter of the hole. The previously demonstrated significant changes in the conductivity of modified bilayer lipid membranes induced by microwave exposure can be explained by a local increase in specific absorption rate and subsequent elevation of temperature in the membrane-forming hole of the Teflon film.

  7. ZnO Nanoparticles/Reduced Graphene Oxide Bilayer Thin Films for Improved NH3-Sensing Performances at Room Temperature.

    Science.gov (United States)

    Tai, Huiling; Yuan, Zhen; Zheng, Weijian; Ye, Zongbiao; Liu, Chunhua; Du, Xiaosong

    2016-12-01

    ZnO nanoparticles and graphene oxide (GO) thin film were deposited on gold interdigital electrodes (IDEs) in sequence via simple spraying process, which was further restored to ZnO/reduced graphene oxide (rGO) bilayer thin film by the thermal reduction treatment and employed for ammonia (NH3) detection at room temperature. rGO was identified by UV-vis absorption spectra and X-ray photoelectron spectroscope (XPS) analyses, and the adhesion between ZnO nanoparticles and rGO nanosheets might also be formed. The NH3-sensing performances of pure rGO film and ZnO/rGO bilayer films with different sprayed GO amounts were compared. The results showed that ZnO/rGO film sensors exhibited enhanced response properties, and the optimal GO amount of 1.5 ml was achieved. Furthermore, the optimal ZnO/rGO film sensor showed an excellent reversibility and fast response/recovery rate within the detection range of 10-50 ppm. Meanwhile, the sensor also displayed good repeatability and selectivity to NH3. However, the interference of water molecules on the prepared sensor is non-ignorable; some techniques should be researched to eliminate the effect of moisture in the further work. The remarkably enhanced NH3-sensing characteristics were speculated to be attributed to both the supporting role of ZnO nanoparticles film and accumulation heterojunction at the interface between ZnO and rGO. Thus, the proposed ZnO/rGO bilayer thin film sensor might give a promise for high-performance NH3-sensing applications.

  8. Electric field-controlled magnetization in bilayered magnetic films for magnetoelectric memory

    Science.gov (United States)

    Yang, Wei-Gang; Morley, Nicola A.; Rainforth, W. Mark

    2015-07-01

    Bilayered magnetic films (Co50Fe50 (CoFe)/Metglas) were RF sputtered on both (001)-oriented and (011)-oriented PMN-PT (lead magnesium niobate-lead titanate) substrates. Electric field-controlled magnetization changes were observed in all these samples: 65 nm CoFe/24 nm Metglas/(001) PMN-PT, 65 nm CoFe/24 nm Metglas/(011) PMN-PT, and 30 nm CoFe/12 nm Metglas/(011) PMN-PT. The maximum magnetic remanence ratio change (ΔMr/Ms) was 46% for CoFe/Metglas/(001) PMN-PT. In this heterostructure, the electric-field created two new non-volatile switchable remanence states and the as-grown remanence state was altered permanently. High-resolution transmission electron microscopy images show a sharp and smooth interface between Metglas and substrate and conversely a rougher interface was observed between Metglas and CoFe films. In the 30 nm CoFe/12 nm Metglas/(011) PMN-PT sample, a large ΔMr/Ms of 80% along the [100] direction was measured, while the ΔMr/Ms along the [01-1] direction was 60% at the applied electric field of 5 kV/cm, corresponding to a giant magnetoelectric coupling constant α = μoΔMr/E = 2.9 × 10-6 s/m.

  9. On diffusion-controlled interface microstructure of vapor deposited bilayer thin film of Sn/Cu

    Indian Academy of Sciences (India)

    T B Ghosh; Sampa Dhabal

    2004-06-01

    Depth dependent concentration profiles for bilayer film of Sn (500 Å)/Cu (500 Å) are determined at di®erent temperatures by X-ray photoelectron spectroscopy (XPS). Although the nature of the diffusion profile for the sample studied immediately after deposition could be explained by the existing laws, the profiles for others are found to be distinctly different and are not explained by the theories of nucleation and growth of the inter-metallic phases. Measured value of the inter-diffusion coefficient for Cu points out to the grain boundary as well as interstitial diffusion processes. It is also observed that the compositions across the bulk of the films become uniform on annealing at higher temperatures and the width of this region increases with annealing. However, the composition close to the surface is found to be entirely different from that of the bulk even on prolonged heating. The findings possibly demonstrate the importance of physical surface in influencing the solid-state reactions.

  10. Rational Design of ZnO:H/ZnO Bilayer Structure for High-Performance Thin-Film Transistors.

    Science.gov (United States)

    Abliz, Ablat; Huang, Chun-Wei; Wang, Jingli; Xu, Lei; Liao, Lei; Xiao, Xiangheng; Wu, Wen-Wei; Fan, Zhiyong; Jiang, Changzhong; Li, Jinchai; Guo, Shishang; Liu, Chuansheng; Guo, Tailiang

    2016-03-01

    The intriguing properties of zinc oxide-based semiconductors are being extensively studied as they are attractive alternatives to current silicon-based semiconductors for applications in transparent and flexible electronics. Although they have promising properties, significant improvements on performance and electrical reliability of ZnO-based thin film transistors (TFTs) should be achieved before they can be applied widely in practical applications. This work demonstrates a rational and elegant design of TFT, composed of poly crystalline ZnO:H/ZnO bilayer structure without using other metal elements for doping. The field-effect mobility and gate bias stability of the bilayer structured devices have been improved. In this device structure, the hydrogenated ultrathin ZnO:H active layer (∼3 nm) could provide suitable carrier concentration and decrease the interface trap density, while thick pure-ZnO layer could control channel conductance. Based on this novel structure, a high field-effect mobility of 42.6 cm(2) V(-1) s(-1), a high on/off current ratio of 10(8) and a small subthreshold swing of 0.13 V dec(-1) have been achieved. Additionally, the bias stress stability of the bilayer structured devices is enhanced compared to the simple single channel layer ZnO device. These results suggest that the bilayer ZnO:H/ZnO TFTs have a great potential for low-cost thin-film electronics.

  11. The Preparation and Properties of DSSC CuAl2O4/TiO2 Photoanodes%染料敏化太阳电池CuAl2O4/TiO2光阳极制备及性能

    Institute of Scientific and Technical Information of China (English)

    胡志强; 刘显卿; 黄德锋; 高宏

    2012-01-01

    采用柠檬酸法制备了尖晶石型纳米晶CuA12O4,将其添加到P25(degussa,TiO2)中,制备成CuAl2O4/TiO2薄膜光阳极,并组装成染料敏化太阳电池(DSSC),对其光电性能进行表征.结果表明:CuAl2O4的加入,电池性能得到提高;当CuAl2O4含量为2%(质量分数)时,与纯TiO2薄膜光阳极相比,光电转化效率提高了39.1%.%CuAl2O4/TiO2 thin film photoanodes were prepared by doping spinel CuAl2O4 nanocrystal-line prepared by the citrate method into P25 (degussa, TiO2), and then assembled into Dye-sensitized solar cells(DSSC) and characterized the photoelectric properties. The results showed that performance of DSSC increase when doped CuAl2O4. When the doping amount is 2% (mass fraction), the photoelectric conversion efficiency was 39. 1% higher than the pure TiO2 thin film photoanodes.

  12. Characteristics of TiO2/ZnO bilayer film towards pH sensitivity prepared by different spin coating deposition process

    Science.gov (United States)

    Rahman, Rohanieza Abdul; Zulkefle, Muhammad Al Hadi; Abdullah, Wan Fazlida Hanim; Rusop, M.; Herman, Sukreen Hana

    2016-07-01

    In this study, titanium dioxide (TiO2) and zinc oxide (ZnO) bilayer film for pH sensing application will be presented. TiO2/ZnO bilayer film with different speed of spin-coating process was deposited on Indium Tin Oxide (ITO), prepared by sol-gel method. This fabricated bilayer film was used as sensing membrane for Extended Gate Field-Effect Transistor (EGFET) for pH sensing application. Experimental results indicated that the sensor is able to detect the sensitivity towards pH buffer solution. In order to obtained the result, sensitivity measurement was done by using the EGFET setup equipment with constant-current (100 µA) and constant-voltage (0.3 V) biasing interfacing circuit. TiO2/ZnO bilayer film which the working electrode, act as the pH-sensitive membrane was connected to a commercial metal-oxide semiconductor FET (MOSFET). This MOSFET then was connected to the interfacing circuit. The sensitivity of the TiO2 thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. These thin films were characterized by using Field Emission Scanning Electron Microscope (FESEM) to obtain the surface morphology of the composite bilayer films. In addition, I-V measurement was done in order to determine the electrical properties of the bilayer films. According to the result obtained in this experiment, bilayer film that spin at 4000 rpm, gave highest sensitivity which is 52.1 mV/pH. Relating the I-V characteristic of the thin films and sensitivity, the sensing membrane with higher conductivity gave better sensitivity.

  13. Uptake of Sc 3+ and La 3+ from aqueous solution using ethylenediaminetetraacetate-intercalated Cu-Al layered double hydroxide reconstructed from Cu-Al oxide

    Science.gov (United States)

    Kameda, Tomohito; Hoshi, Kazuaki; Yoshioka, Toshiaki

    2011-02-01

    A Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate (edta·Cu-Al LDH) was prepared by suspending Cu-Al oxide, obtained by the calcination of CO32--intercalated Cu-Al LDH, in edta solution. It was found that the reconstruction of Cu-Al oxide to Cu-Al LDH was promoted with an increase in the temperature and time. The reaction in the pH range of around 8 suggests that Hedta 3- was intercalated in the interlayer of Cu-Al LDH. Edta·Cu-Al LDH was found to take up rare metal ions such as Sc 3+ and La 3+ in an aqueous solution at a pH of around 6-6.5. The uptake of Sc 3+ was caused not only by the chelating function of Hedta 3- in the interlayer but also by the chemical behavior of Cu-Al LDH itself. On the other hand, the uptake of La 3+ was caused only by the chelating function of Hedta 3- in the interlayer. The Hedta 3- in the interlayer of edta·Cu-Al LDH had the potential to form a chelate complex more preferentially with Sc 3+ than with La 3+.

  14. Study on the enhanced and stable field emission behavior of a novel electrosprayed Al-doped ZnO bilayer film

    KAUST Repository

    Mahmood, Khalid

    2014-01-01

    A novel electrosprayed bilayer film composed of an over-layer (L 2) of aluminium-doped ZnO (AZO) nanoflakes (NF-AZO) and a under-layer (L1) of AZO nanocrystallites structure (NC-AZO) named BL:NF/NC-AZO is studied as an excellent field-emitter. The XRD pattern demonstrated that the doped bilayer film has preferential growth along the c-axis with hexagonal wurtzite structure and the (0 0 2) peak shifted toward the larger angle side after doping. The lowest turn-on field of ∼2.8 V μm-1, highest emission current density of 1.95 mA cm-2 is obtained for BL:NF/NC-AZO under the field of 6.8 V μm-1 and as well as the highest field enhancement factor (β) is estimated to be 4370 ± 3, compared to pure ZnO bilayer film (BL:NF/NC-ZnO) and also better than NC-AZO film and possesses the excellent long term stability of emission current. The PL intensity of doped ZnO bilayer film is very much stronger than pure ZnO bilayer structure. The superior field emission properties are attributed to the better morphologies, Al-doping and better crystallinity of bilayer AZO films. © 2014 The Royal Society of Chemistry.

  15. Atomic diffusion behavior in Cu-Al explosive welding process

    Science.gov (United States)

    Chen, S. Y.; Wu, Z. W.; Liu, K. X.; Li, X. J.; Luo, N.; Lu, G. X.

    2013-01-01

    A hybrid method is proposed to study atomic diffusion behavior in Cu-Al explosive welding process. The method combines molecular dynamics simulation and classical diffusion theory. Cu-Al explosive welding and scanning electron microscope experiments are done to verify the method. Using the method, we find that the atomic diffusion mostly takes place in the unloading stage of the welding process. The diffusion coefficients are collision velocity-dependent, with higher velocities generating larger coefficients. When there is no transverse velocity, the diffusion coefficient is directly proportional to the longitudinal velocity. With the longitudinal velocity fixed, the diffusion coefficient is proportional to the square of the transverse velocity. The thickness of the diffusion layer is calculated from the simulation result, and it is in good agreement with the experiment result.

  16. Investigation on contact melting of Cu/Al laminated composite

    Directory of Open Access Journals (Sweden)

    Dmitry V. Pronichev

    2016-12-01

    Full Text Available The study presents investigation of chemical composition, microhardness and electrical conductivity of Cu/Al laminated metal composite after heat treatment at temperatures higher than Cu–Al eutectic melting point. The Cu/Al bimetal was obtained via explosion welding. Chemical composition of the material after heat treatments was identified using EDS analysis. Eddy current testing was applied to investigate electrical conductivity of the composite’s components. Strain-hardened zones were identified in the explosion welded composite. The experimental value of electrical conductivity of explosion welded composite was in good coherence with calculated by additivity rule results. Heat treatments resulted in the formation of multiple interlayers which had high microhardness value and had intermetallics in composition. The electrical conductivity of the identified interlayers was significantly lower than of Cu and Al.

  17. ZnO Nanoparticles/Reduced Graphene Oxide Bilayer Thin Films for Improved NH3-Sensing Performances at Room Temperature

    OpenAIRE

    Tai, Huiling; Yuan, Zhen; Zheng, Weijian; Ye, Zongbiao; Liu, Chunhua; Du, Xiaosong

    2016-01-01

    ZnO nanoparticles and graphene oxide (GO) thin film were deposited on gold interdigital electrodes (IDEs) in sequence via simple spraying process, which was further restored to ZnO/reduced graphene oxide (rGO) bilayer thin film by the thermal reduction treatment and employed for ammonia (NH3) detection at room temperature. rGO was identified by UV-vis absorption spectra and X-ray photoelectron spectroscope (XPS) analyses, and the adhesion between ZnO nanoparticles and rGO nanosheets might als...

  18. Solid-state dewetting of single- and bilayer Au-W thin films: Unraveling the role of individual layer thickness, stacking sequence and oxidation on morphology evolution

    Directory of Open Access Journals (Sweden)

    A. Herz

    2016-03-01

    Full Text Available Self-assembly of ultrathin Au, W, and Au-W bilayer thin films is investigated using a rapid thermal annealing technique in an inert ambient. The solid-state dewetting of Au films is briefly revisited in order to emphasize the role of initial film thickness. W films deposited onto SiO2 evolve into needle-like nanocrystals rather than forming particle-like agglomerates upon annealing at elevated temperatures. Transmission electron microscopy reveals that such nanocrystals actually consist of tungsten (VI oxide (WO3 which is related to an anisotropic oxide crystal growth out of the thin film. The evolution of W films is highly sensitive to the presence of any residual oxygen. Combination of both the dewetting of Au and the oxide crystal growth of WO3 is realized by using various bilayer film configurations of the immiscible Au and W. At low temperature, Au dewetting is initiated while oxide crystal growth is still suppressed. Depending on the stacking sequence of the Au-W bilayer thin film, W acts either as a substrate or as a passivation layer for the dewetting of Au. Being the ground layer, W changes the wettability of Au which clearly modifies its initial state for the dewetting. Being the top layer, W prevents Au from dewetting regardless of Au film thickness. Moreover, regular pattern formation of Au-WO3 nanoparticles is observed at high temperature demonstrating how bilayer thin film dewetting can create unique nanostructure arrangements.

  19. Controlling the Performance of P-type Cu2O/SnO Bilayer Thin-Film Transistors by Adjusting the Thickness of the Copper Oxide Layer

    KAUST Repository

    Al-Jawhari, Hala A.

    2014-11-11

    The effect of copper oxide layer thickness on the performance of Cu2O/SnO bilayer thin-film transistors was investigated. By using sputtered Cu2O films produced at an oxygen partial pressure, Opp, of 10% as the upper layer and 3% Opp SnO films as the lower layer we built a matrix of bottom-gate Cu2O/SnO bilayer thin-film transistors of different thickness. We found that the thickness of the Cu2O layer is of major importance in oxidation of the SnO layer underneath. The thicker the Cu2O layer, the more the underlying SnO layer is oxidized, and, hence, the more transistor mobility is enhanced at a specific temperature. Both device performance and the annealing temperature required could be adjusted by controlling the thickness of each layer of Cu2O/SnO bilayer thin-film transistors.

  20. Microstructural changes and fractal Ge nanocrystallites in polycrystalline Au/amorphous Ge thin bilayer films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z W; Lai, J K L; Shek, C H [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)

    2006-11-07

    Microstructural changes and fractal Ge nanocrystallites in polycrystalline Au/amorphous Ge thin bilayer films upon annealing have been investigated by scanning electron microscopy, transmission electron microscopy observations and x-ray energy-dispersive spectroscopy (EDS). Experimental results indicated that the microstructure of the metal Au film plays an important role in metal-induced crystallization for Au/Ge thin bilayer films upon annealing. Interestingly, we found the position exchange of Au and Ge films and the formation of the fractal Ge nanocrystallites induced by annealing. EDS microanalysis indicated that although there is lateral interdiffusion of Au and Ge atoms, the thickness of the fractal region and the matrix remain nearly the same. At the same time, EDS shows that there are also Au aggregates extending out of the films. It is suggested that, besides the preferred nucleation at the Au/Ge interface, the breaking of Ge-Ge bonds may stimulate the crystallization of amorphous Ge, so that the crystallization temperature of Au/Ge system is much lower than that of the isolated amorphous Ge system.

  1. Microstructural changes and fractal Ge nanocrystallites in polycrystalline Au/amorphous Ge thin bilayer films upon annealing

    Science.gov (United States)

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.

    2006-11-01

    Microstructural changes and fractal Ge nanocrystallites in polycrystalline Au/amorphous Ge thin bilayer films upon annealing have been investigated by scanning electron microscopy, transmission electron microscopy observations and x-ray energy-dispersive spectroscopy (EDS). Experimental results indicated that the microstructure of the metal Au film plays an important role in metal-induced crystallization for Au/Ge thin bilayer films upon annealing. Interestingly, we found the position exchange of Au and Ge films and the formation of the fractal Ge nanocrystallites induced by annealing. EDS microanalysis indicated that although there is lateral interdiffusion of Au and Ge atoms, the thickness of the fractal region and the matrix remain nearly the same. At the same time, EDS shows that there are also Au aggregates extending out of the films. It is suggested that, besides the preferred nucleation at the Au/Ge interface, the breaking of Ge-Ge bonds may stimulate the crystallization of amorphous Ge, so that the crystallization temperature of Au/Ge system is much lower than that of the isolated amorphous Ge system.

  2. Strain-Induced Energy Band Gap Opening in Two-Dimensional Bilayered Silicon Film

    Science.gov (United States)

    Ji, Z.; Zhou, R.; Lew Yan Voon, L. C.; Zhuang, Y.

    2016-10-01

    This work presents a theoretical study of the structural and electronic properties of bilayered silicon film (BiSF) under in-plane biaxial strain/stress using density functional theory (DFT). Atomic structures of the two-dimensional (2-D) silicon films are optimized by using both the local-density approximation (LDA) and generalized gradient approximation (GGA). In the absence of strain/stress, five buckled hexagonal honeycomb structures of the BiSF with triangular lattice have been obtained as local energy minima, and their structural stability has been verified. These structures present a Dirac-cone shaped energy band diagram with zero energy band gaps. Applying a tensile biaxial strain leads to a reduction of the buckling height. Atomically flat structures with zero buckling height have been observed when the AA-stacking structures are under a critical biaxial strain. Increase of the strain between 10.7% and 15.4% results in a band-gap opening with a maximum energy band gap opening of ˜0.17 eV, obtained when a 14.3% strain is applied. Energy band diagrams, electron transmission efficiency, and the charge transport property are calculated. Additionally, an asymmetric energetically favorable atomic structure of BiSF shows a non-zero band gap in the absence of strain/stress and a maximum band gap of 0.15 eV as a -1.71% compressive strain is applied. Both tensile and compressive strain/stress can lead to a band gap opening in the asymmetric structure.

  3. Electric field-controlled magnetization in bilayered magnetic films for magnetoelectric memory

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wei-Gang; Morley, Nicola A.; Rainforth, W. Mark, E-mail: m.rainforth@sheffield.ac.uk [Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2015-07-21

    Bilayered magnetic films (Co{sub 50}Fe{sub 50} (CoFe)/Metglas) were RF sputtered on both (001)-oriented and (011)-oriented PMN-PT (lead magnesium niobate-lead titanate) substrates. Electric field-controlled magnetization changes were observed in all these samples: 65 nm CoFe/24 nm Metglas/(001) PMN-PT, 65 nm CoFe/24 nm Metglas/(011) PMN-PT, and 30 nm CoFe/12 nm Metglas/(011) PMN-PT. The maximum magnetic remanence ratio change (ΔM{sub r}/M{sub s}) was 46% for CoFe/Metglas/(001) PMN-PT. In this heterostructure, the electric-field created two new non-volatile switchable remanence states and the as-grown remanence state was altered permanently. High-resolution transmission electron microscopy images show a sharp and smooth interface between Metglas and substrate and conversely a rougher interface was observed between Metglas and CoFe films. In the 30 nm CoFe/12 nm Metglas/(011) PMN-PT sample, a large ΔM{sub r}/M{sub s} of 80% along the [100] direction was measured, while the ΔM{sub r}/M{sub s} along the [01-1] direction was 60% at the applied electric field of 5 kV/cm, corresponding to a giant magnetoelectric coupling constant α = μ{sub o}ΔM{sub r}/E = 2.9 × 10{sup −6} s/m.

  4. Growth feature of ionic nitrogen doped CN{sub x} bilayer films with Ti and TiN interlayer by pulse cathode arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Bing, E-mail: zhoubing@tyut.edu.cn [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Zhubo [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Piliptsou, D.G., E-mail: pdg_@mail.ru [International Chinese–Belarusian Scientific Laboratory on Vacuum-Plasma Technology, Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Nanjing University of Science and Technology, Nanjing 210094 (China); Rogachev, A.V. [International Chinese–Belarusian Scientific Laboratory on Vacuum-Plasma Technology, Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Nanjing University of Science and Technology, Nanjing 210094 (China); Yu, Shengwang; Wu, Yanxia; Tang, Bin [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Rudenkov, A.S. [International Chinese–Belarusian Scientific Laboratory on Vacuum-Plasma Technology, Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Nanjing University of Science and Technology, Nanjing 210094 (China)

    2016-01-15

    Graphical abstract: - Highlights: • Ti/ and TiN/CN{sub x} (N{sup +}) bilayers are prepared at various frequencies by pulse cathode arc. • Ti interlayer facilitates the introduction of N atoms into the CN{sub x} (N{sup +}) films. • The most N-sp{sup 2}C bonds (mainly graphite-like N) present in the TiN/CN{sub x} (N{sup +}, 3 Hz) film. • Ti/CN{sub x} (N{sup +}, 3 Hz) bilayer possesses small size and disordering of Csp{sup 2} clusters. • The higher hardness and the lower stress presents in the TiN/CN{sub x} (N{sup +}, 10 Hz) bilayer. - Abstract: Using nano-scaled Ti and TiN as interlayer, ionic nitrogen doped carbon (CN{sub x} (N{sup +})) bilayer films were prepared at various pulse frequencies by cathode arc technique. Elemental distribution at the interface, bonding compositions, microstructure, and mechanical properties of CN{sub x} (N{sup +}) bilayer films were investigated in dependence of interlayer and pulse frequency by Auger electron spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, nanoindentation, and surface profilometer. The results showed that the diffusion extent of C atoms at the interface of CN{sub x} (N{sup +}) bilayers is higher than for the α-C and CN{sub x} (N{sub 2}) bilayers with the same interlayer. Nitrogen atoms could diffuse throughout the pre-deposited Ti and TiN layers into the Si substrate for all CN{sub x} (N{sup +}) bilayers. Ti interlayer facilitates the introduction of N atoms into the CN{sub x} (N{sup +}) films and exhibits a certain catalytic effect on the coordination of N atoms with sp{sup 2}- and sp{sup 3}-C binding. More nitrogenated and intense CN bonding configurations (mainly graphite-like N) form in the TiN/CN{sub x} (N{sup +}) bilayer. Ti/CN{sub x} (N{sup +}) bilayer prepared at low frequency possesses small size and disordering of Csp{sup 2} clusters but TiN interlayer weakens the formation of Csp{sup 2} bonding and increases the disordering of Csp{sup 2} clusters in the films. The residual

  5. Room-temperature magneto-dielectric response in multiferroic ZnFe2O4/PMN-PT bilayer thin films

    Science.gov (United States)

    Garg, T.; Kulkarni, A. R.; Venkataramani, N.

    2016-08-01

    The magneto-dielectric response in multiferroic ZnFe2O4/PMN-PT bilayer thin films prepared on a glass substrate using RF magnetron sputtering has been investigated in this work. PMN-PT thin films (i.e. PMN-PT/LCMO/Pt/Ti/glass) deposited on glass were used as a substrate for deposition of ZnFe2O4 thin films. ZnFe2O4 thin films were annealed ex situ at different temperatures. Structural, magnetic, ferroelectric, dielectric and magneto-dielectric studies were carried out on these multiferroic bilayer thin films. Structural studies revealed the presence of each layer in its respective single phase. Magnetic and ferroelectric studies revealed the ferromagnetic and ferroelectric behaviors of these bilayers. To quantify the magnetoelectric coupling, the dielectric constant of the bilayer was measured at room temperature as a function of frequency with and without the applied magnetic field. The magneto-dielectric response MD(%) was calculated by finding the relative change in dielectric constant at 1 kHz as a percentage. The observed MD response was correlated with magnetization of the ferrite layer. An MD response of 2.60% was found for a bilayer film annealed at 350 °C. At this particular annealing temperature, the ZnFe2O4 layer also has the highest saturation magnetization of 1900 G.

  6. Antireflective bilayer coatings based on Al2O3 film for UV region

    Directory of Open Access Journals (Sweden)

    Marszałek Konstanty

    2015-03-01

    Full Text Available Bilayer antireflective coatings consisting of aluminium oxide Al2O3/MgF2 and Al2O3/SiO2 are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5 × 10-3 Pa in the presence of oxygen, and magnesium fluoride was prepared by thermal evaporation on heated optical lenses made from quartz glass (Corning HPFS. Substrate temperature was maintained at 250 _C during the deposition. Thickness and deposition rate were controlled with a thickness measuring system Inficon XTC/2. The experimental results of the optical measurements carried out during and after the deposition process have been presented. Physical thickness measurements were made during the deposition process and resulted in 44 nm/52 nm for Al2O3/MgF2 and 44 nm/50 nm for Al2O3/SiO2 system. Optimization was carried out for ultraviolet region with minimum of reflectance at 300 nm. The influence of post deposition annealing on the crystal structure was determined by X-ray measurements. In the range from ultraviolet to the beginning of visible region, the reflectance of both systems decreased and reached minimum at 290 nm. The value of reflectance at this point, for the coating Al2O3/MgF2 was equal to R290nm = 0.6 % and for Al2O3/SiO2R290nm = 1.1 %. Despite the difference between these values both are sufficient for applications in the UV optical systems for medicine and UV laser technology.

  7. Growth and Chemical Thermodynamics Analysis of SiC Film on Si Substrate by Heating Polystyrene/Silica Bilayer Method

    Science.gov (United States)

    Li, Yun; Wang, Yu-xia; Chen, Zheng; Wang, Jian-wen; Zou, You-ming

    2008-04-01

    SiC films were prepared by modified heating polystyrene/silica bilayer method on Si (111) substrate in normal pressure flowing Ar ambient at 1300°C. The films were investigated by Fourier transform infrared absorption, X-ray diffraction, and scanning electron microscopy measurements. The chemical thermodynamics process is discussed. The whole reaction can be separated into four steps. The carburizing of SiO is the key step of whole reaction. The main reaction-sequence is figured out based on Gibbs free energy and equilibrium constant. Flowing Ar is necessary to continue the progress of whole reaction by means of carrying out accumulating gaseous resultants. The film is very useful for application in a variety of MOS-based devices for its silica/SiC/Si(111) structure, in which the silica layer can be removed thoroughly by the standard RCA cleaning process.

  8. Supercoducting property of Zr-Cu-Al-Ni-Nb alloys

    Science.gov (United States)

    Okai, D.; Motoyama, G.; Kimura, H.; Inoue, A.

    The superconducting property of Zr55Cu(30-X)Al10Ni5NbX alloys prepared by arc melting and liquid quenching methods was investigated by magnetic susceptibility measurements. The crystalline alloys with X = 0∼25 at.% prepared by arc melting method exhibited superconductivity with maximum Tc,on of 10.1 K. The alloys (X = 10∼23 at.%) with crystalline particles embedded in an amorphous structure, which were fabricated by melt spinning method, showed superconductivity with Tc,on of less than 4.0 K. The superconducting property of the Zr-Cu-Al-Ni-Nb alloys was attributed to superconducting phases of Zr2Cu, Zr2Ni, Zr65Al10Nb25 and Zr-Nb contained in the Zr-Cu-Al-Ni-Nb alloys. The melt-spun Zr55Cu(30-X)Al10Ni5NbX (X = 10∼20 at.%) alloys exhibited glass transition at 718∼743 K and were found to be superconducting metallic glasses.

  9. Thickness dependence of spin torque ferromagnetic resonance in Co{sub 75}Fe{sub 25}/Pt bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Ganguly, A.; Barman, A., E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sec III, Salt Lake, Kolkata 700 098 (India); Kondou, K., E-mail: kkondou@riken.jp [RIKEN-CEMS, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sukegawa, H.; Mitani, S. [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Kasai, S. [RIKEN-CEMS, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Niimi, Y. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581 (Japan); Otani, Y. [RIKEN-CEMS, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581 (Japan)

    2014-02-17

    The spin Hall angle of Pt in Co{sub 75}Fe{sub 25}/Pt bilayer films was experimentally investigated by means of the spin-torque ferromagnetic resonance and the modulation of damping measurements. By comparing the present results with the Ni{sub 80}Fe{sub 20}/Pt system, we found that the ferromagnetic layer underneath the Pt one greatly affects the estimation of the spin Hall angle. We also discuss the spin diffusion length of Pt and the ferromagnetic thickness dependence of the Gilbert damping coefficient.

  10. Assembly of 1D nanofibers into a 2D bi-layered composite nanofibrous film with different functionalities at the two layers via layer-by-layer electrospinning.

    Science.gov (United States)

    Wang, Zijiao; Ma, Qianli; Dong, Xiangting; Li, Dan; Xi, Xue; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

    2016-12-21

    A two-dimensional (2D) bi-layered composite nanofibrous film assembled by one-dimensional (1D) nanofibers with trifunctionality of electrical conduction, magnetism and photoluminescence has been successfully fabricated by layer-by-layer electrospinning. The composite film consists of a polyaniline (PANI)/Fe3O4 nanoparticle (NP)/polyacrylonitrile (PAN) tuned electrical-magnetic bifunctional layer on one side and a Tb(TTA)3(TPPO)2/polyvinylpyrrolidone (PVP) photoluminescent layer on the other side, and the two layers are tightly combined face-to-face together into the novel bi-layered composite film of trifunctionality. The brand-new film has totally different characteristics at the double layers. The electrical conductivity and magnetism of the electrical-magnetic bifunctional layer can be, respectively, tunable via modulating the PANI and Fe3O4 NP contents, and the highest electrical conductivity can reach up to the order of 10(-2) S cm(-1), and predominant intense green emission at 545 nm is obviously observed in the photoluminescent layer under the excitation of 357 nm single-wavelength ultraviolet light. More importantly, the luminescence intensity of the photoluminescent layer remains almost unaffected by the electrical-magnetic bifunctional layer because the photoluminescent materials have been successfully isolated from dark-colored PANI and Fe3O4 NPs. By comparing with the counterpart single-layered composite nanofibrous film, it is found that the bi-layered composite nanofibrous film has better performance. The novel bi-layered composite nanofibrous film with trifunctionality has potential in the fields of nanodevices, molecular electronics and biomedicine. Furthermore, the design conception and fabrication technique for the bi-layered multifunctional film provide a new and facile strategy towards other films of multifunctionality.

  11. Two-step preparation of laser-textured Ni/FTO bilayer composite films with high photoelectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bao-jia, E-mail: li_bjia@126.com [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); Huang, Li-jing [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); Ren, Nai-fei [Jiangsu Provincial Key Laboratory for Science and Technology of Photon Manufacturing, Jiangsu University, Zhenjiang 212013 (China); School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Kong, Xia; Cai, Yun-long; Zhang, Jie-lu [Jiangsu Tailong Reduction Box Co. Ltd, Taixing 225400 (China)

    2015-08-15

    Highlights: • A two-step strategy was proposed to prepare laser-textured Ni/FTO composite films. • Ni/FTO film with a 10-nm-thick Ni layer (Ni{sub 10}/FTO film) had the best performance. • The Ni{sub 10}/FTO film underwent magnetic-field-assisted and -free laser irradiations. • All the magnetic laser-irradiated (MLI-NF) films were textured and annealed. • The MLI-NF film using a fluence of 1.0 J/cm{sup 2} showed the highest figure of merit. - Abstract: A two-step strategy, i.e. sputtering Ni layers on FTO glass combined with magnetic-field-assisted laser irradiation, was proposed to prepare laser-textured Ni/FTO bilayer composite films. By analyzing surface morphology, crystal structure and photoelectric properties of Ni/FTO films with different Ni layer thicknesses, the Ni/FTO film with a 10-nm-thick Ni layer (Ni{sub 10}/FTO film), which had the best overall photoelectric property, was chosen to undergo magnetic-field-assisted laser irradiation with different laser fluences. Magnetic-field-free laser irradiation of the Ni{sub 10}/FTO film was also carried out for comparison purpose. It was found that magnetic-field-assisted laser irradiation using a fluence of 1.0 J/cm{sup 2} was more effective for simultaneously achieving texturing and annealing, resulting in formation of ideal grating textures and significantly increased grain size. The corresponding film (MLI-NF1.0 film) showed the highest figure of merit of 22.8 × 10{sup −3} Ω{sup −1} compared to 13.1 × 10{sup −3} Ω{sup −1} of the FTO glass and 1.4 × 10{sup −3} Ω{sup −1} of the Ni{sub 10}/FTO film, suggesting that the two-step strategy is excellent for preparing textured Ni/FTO films with high photoelectric properties.

  12. A novel hierarchical ZnO disordered/ordered bilayer nanostructured film for dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yamin, E-mail: yaminfengccnuphy@outlook.com; Wu, Fei; Jiang, Jian; Zhu, Jianhui; Fodjouong, Ghislain Joel; Meng, Gaoxiang; Xing, Yanmin; Wang, Wenwu; Huang, Xintang, E-mail: xthuang@phy.ccnu.edu.cn

    2013-12-25

    Graphical abstract: A novel hierarchical disordered/ordered bilayer ZnO nanostructured film in the length of 18 μm have been successfully synthesized on the FTO substrate; the hierarchical ZnO nanostructured film electrodes applied in DSSCs exhibit photoelectric conversion efficiency as high as 5.16%. Highlights: •A novel hierarchical ZnO structure film was fabricated on a FTO substrate. •Hierarchical ZnO film is applied as the electrodes for dye sensitized solar cells. •The film possess high specific surface area and fast electron transport effect. •The light-scattering effect of the hierarchical film is pronounced. •The energy conversion efficiency of hierarchical ZnO electrode reaches to 5.16%. -- Abstract: A novel hierarchical ZnO nanostructured film is synthesized via a chemical bath deposition (CBD) method followed by a treatment of thermal decomposition onto a fluorine-doped tin oxide (FTO) substrate. This hierarchical film is composed of disordered ZnO nanorods (NRs) (top layer) and ordered ZnO nanowires (NWs) (bottom layer). The products possess the following features such as high specific surface area, fast electron transport, and pronounced light-scattering effect, which are quite suitable for dye sensitized solar cells (DSSCs) applications. A light-to-electricity conversion efficiency of 5.16% is achieved when the hierarchical ZnO nanostructured film is used as the photoanode under 100 mW cm{sup −2} illumination. This efficiency is found to be much higher than that of the DSSCs with pure ordered ZnO NWs (1.45%) and disordered ZnO NRs (3.31%) photoanodes.

  13. Reaction kinetics of CuGaSe 2 formation from a GaSe/CuSe bilayer precursor film

    Science.gov (United States)

    Kim, W. K.; Payzant, E. A.; Kim, S.; Speakman, S. A.; Crisalle, O. D.; Anderson, T. J.

    2008-06-01

    The reaction pathway and kinetics of CuGaSe 2 formation were investigated by monitoring the phase evolution of temperature ramp annealed or isothermally soaked bilayer glass/GaSe/CuSe precursor film using time-resolved, in situ high-temperature X-ray diffraction. Bilayer GaSe/CuSe precursor films were deposited on alkali-free thin glass substrates in a migration-enhanced epitaxial deposition system. The initial CuSe phase begins to transform to β-Cu 2-xSe at around 230 °C, followed by CuGaSe 2 formation accompanied by a decrease in the β-Cu 2-xSe peak intensity at around 260 °C. Both the parabolic and Avrami diffusion-controlled reaction models represented the experimental data very well over the entire temperature range (280-370 °C) of the set of isothermal experiments with estimated activation energies of 115(±16) and 124(±19) kJ/mol, respectively. Transmission electron microscopy-energy-dispersive X-ray spectrometry (TEM-EDS) analysis suggests that CuGaSe 2 forms at the interface of the initial GaSe and CuSe layers.

  14. Enhanced Stability in Surface Plasmon Resonance Sensor Using Prism Coupler Based on Au/Bi2O3 Bilayer Film

    Directory of Open Access Journals (Sweden)

    Gaoyao Wei

    2013-05-01

    Full Text Available Surface Plasmon Resonance (SPR sensing has become a comprehensive utilized technology for detection, measurement and analysis in a wide spectrum of fields, ranging from biotechnology, environmental monitoring to food and drug monitoring. In this study, Au/Bi2O3 bilayer films with various layer thicknesses were deposited by thermal evaporation method on BK7 prism substrates and then post-annealing was conducted under ambient conditions. The adhesive strength of Au/Bi2O3 and Bi2O3/prism was measured with different layer thicknesses. Also, the SPR responses (reflectance vs. incident angle were investigated as a function of the thickness of Bi2O3 layer in the Kretschmann geometry using ethanol as dielectric. The results indicate that the adhesive strength between Au and prism was improved more than 3 times by introducing the Bi2O3 as buffer layer. And the SPR dips also demonstrate that SPR sensor based on Au/Bi2O3 bilayer films is practical, although the height of SPR dip with about 6nm Bi2O3 is approximately 4 times weaker than that of monolayer Au and the width (defined as FWHM broadens from 9° to 11°.

  15. Improvement of pentathiophene/fullerene planar heterojunction photovoltaic cells by improving the organic films morphology through the anode buffer bilayer

    Science.gov (United States)

    El Jouad, Zouhair; Cattin, Linda; Martinez, Francisco; Neculqueo, Gloria; Louarn, Guy; Addou, Mohammed; Predeep, Padmanabhan; Manuvel, Jayan; Bernède, Jean-Christian

    2016-05-01

    Organic photovoltaic cells (OPVCs) are based on a heterojunction electron donor (ED)/electron acceptor (EA). In the present work, the electron donor which is also the absorber of light is pentathiophene. The typical cells were ITO/HTL/pentathiophene/fullerene/Alq3/Al with HTL (hole transport layer) = MoO3, CuI, MoO3/CuI. After optimisation of the pentathiophene thickness, 70 nm, the highest efficiency, 0.81%, is obtained with the bilayer MoO3/CuI as HTL. In order to understand these results the pentathiophene films deposited onto the different HTLs were characterized by scanning electron microscopy, atomic force microscopy, X-rays diffraction, optical absorption and electrical characterization. It is shown that CuI improves the conductivity of the pentathiophene layer through the modification of the film structure, while MoO3 decreases the leakage current. Using the bilayer MoO3/CuI allows cumulating the advantages of each layer. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  16. Quenching effects in Cu-Al-Mn shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Obrado, E.; Manosa, L.; Planes, A. [Barcelona Univ. (Spain). Dept. d' Estructura i Constituents de la Materia; Romero, R.; Somoza, A. [IFIMAT, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil, and Comision de Investigaciones Cientificas de la Provincia de Buenos Aires, Buenos Aires (Argentina)

    1999-12-15

    In this paper the effect of quenching from different temperatures (T{sub q}) in a Cu-Al-Mn alloy is studied. This alloy system, which displays an L2{sub 1} ordered structure, transforms martensitically at an intermediate temperature T{sub M}, and undergoes a spin freezing process at a lower temperature T{sub f}. Positron annihilation measurements have shown that after the quench, an excess of vacancies is retained in the system, depending on T{sub q}. In addition, both T{sub M} and T{sub f} have been found to be sensitive to T{sub q}. This has been attributed to frozen-in disorder induced by the quench. Experimental results have been interpreted in terms of the growth of magnetic clusters, quenched-in vacancies and atomic disorder. (orig.)

  17. Control of the optical and crystalline properties of TiO{sub 2} in visible-light active TiO{sub 2}/TiN bi-layer thin-film stacks

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Wilson; Fakhouri, Houssam; Pulpytel, Jerome; Arefi-Khonsari, Farzaneh [Laboratoire de Genie des Procedes Plasma et Traitement de Surface, Universite Pierre et Marie Curie, 11 Rue Pierre et Marie Curie, Paris 75231 (France)

    2012-01-15

    Multi-layered thin films of TiO{sub 2} and TiN were created by rf reactive magnetron sputtering, and their crystalline, optical, and photoelectrochemical properties were measured. The overall composition of the films (TiO{sub 2}-to-TiN ratio) was kept constant with the height of each film. The number of layers and thickness of each layer was controlled to create bi-layer thin films that were composed of: 9 bi-layers, 18 bi-layers, 27 bi-layers, 36 bi-layers, and 45 bi-layers. XRD patterns were observed for each film after annealing to measure the grain size and composition of anatase and rutile as a function of temperature. It was found that the phase-transition temperature is able to be substantially controlled (between 550 deg. C and 850 deg. C) for the anatase to rutile transition by varying the number of layers/thickness of each layer. In addition, bi-layer stacking significantly affected the film's optical properties by lowering the bandgap into the visible-light region, and also showed up to three times the improvement in photoelectrochemical performance under uv and visible irradiation. Overall, bi-layer stacking of TiO{sub 2}/TiN films has shown a unique and highly desirable control over several important physical characteristics that can be beneficial for many applications, such as high-temperature sensors and optoelectronic devices.

  18. Enhancement of magnetic circular dichroism in bi-layered ZnO-Bi:YIG thin films

    Directory of Open Access Journals (Sweden)

    Shinichiro Mito

    2017-05-01

    Full Text Available Bi-layered zinc oxide (ZnO and bismuth substituted yttrium iron garnet (Bi:YIG was fabricated and magneto-optically investigated. Enhancement of Faraday rotation and magnetic circular dichroism (MCD was observed. The wavelength of MCD enhancement was in good agreement with exciton wavelength of ZnO. This enhancement was only observed in the bi-layer, and implies that the exciton generated in ZnO interacted with Bi:YIG. Because the exciton wavelength of ZnO can be controlled by electro-optic effect, this result has the potential for realizing voltage control of magneto-optic effect.

  19. Thermo-Optical Properties of Thin-Film TiO2–Al2O3 Bilayers Fabricated by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Rizwan Ali

    2015-05-01

    Full Text Available We investigate the optical and thermo-optical properties of amorphous TiO\\(_2\\–Al\\(_2\\O\\(_3\\ thin-film bilayers fabricated by atomic layer deposition (ALD. Seven samples of TiO\\(_2\\–Al\\(_2\\O\\(_3\\ bilayers are fabricated by growing Al\\(_2\\O\\(_3\\ films of different thicknesses on the surface of TiO\\(_2\\ films of constant thickness (100 nm. Temperature-induced changes in the optical refractive indices of these thin-film bilayers are measured by a variable angle spectroscopic ellipsometer VASE\\textsuperscript{\\textregistered}. The optical data and the thermo-optic coefficients of the films are retrieved and calculated by applying the Cauchy model and the linear fitting regression algorithm, in order to evaluate the surface porosity model of TiO\\(_2\\ films. The effects of TiO\\(_2\\ surface defects on the films' thermo-optic properties are reduced and modified by depositing ultra-thin ALD-Al\\(_2\\O\\(_3\\ diffusion barrier layers. Increasing the ALD-Al\\(_2\\O\\(_3\\ thickness from 20 nm to 30 nm results in a sign change of the thermo-optic coefficient of the ALD-TiO\\(_2\\. The thermo-optic coefficients of the 100 nm-thick ALD-TiO\\(_2\\ film and 30 nm-thick ALD-Al\\(_2\\O\\(_3\\ film in a bilayer are (0.048 \\(\\pm\\ 0.134 \\(\\times 10 ^{-4} {^\\circ}\\mathrm {C}^{-1}\\ and (0.680 \\(\\pm\\ 0.313 \\(\\times 10^{-4} {^\\circ} \\mathrm {C}^{-1}\\, respectively, at a temperature \\(T = 62 ^\\circ \\mathrm{C}\\.

  20. Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells

    Science.gov (United States)

    Jenatsch, Sandra; Geiger, Thomas; Heier, Jakob; Kirsch, Christoph; Nüesch, Frank; Paracchino, Adriana; Rentsch, Daniel; Ruhstaller, Beat; C Véron, Anna; Hany, Roland

    2015-01-01

    Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability. PMID:27877804

  1. Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells.

    Science.gov (United States)

    Jenatsch, Sandra; Geiger, Thomas; Heier, Jakob; Kirsch, Christoph; Nüesch, Frank; Paracchino, Adriana; Rentsch, Daniel; Ruhstaller, Beat; C Véron, Anna; Hany, Roland

    2015-06-01

    Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability.

  2. The Influence of New Hydrophobic Silica Nanoparticles on the Surface Properties of the Films Obtained from Bilayer Hybrids

    Science.gov (United States)

    Petcu, Cristian; Purcar, Violeta; Spătaru, Cătălin-Ilie; Alexandrescu, Elvira; Şomoghi, Raluca; Trică, Bogdan; Niţu, Sabina Georgiana; Panaitescu, Denis Mihaela; Donescu, Dan; Jecu, Maria-Luiza

    2017-01-01

    Ultra-hydrophobic bilayer coatings on a glass surface were fabricated by sol–gel process using hexadecyltrimethoxysilane (C16TMS) and tetramethoxysilane (TMOS) (1:4 molar ratio) as precursors. After coating, silica nanoparticles (SiO2 NPs) functionalized with different mono-alkoxy derivatives (methoxytrimethylsilane, TMeMS; ethoxydimethylvinylsilane, DMeVES; ethoxydimethylphenylsilane, DMePhES; and methoxydimethyloctylsilane, DMeC8MS) were added, assuring the microscale roughness on the glass surface. Influences of the functionalized SiO2 NPs and surface morphology on the hydrophobicity of the hybrid films were discussed. The successful functionalization of SiO2 NPs with hydrophobic alkyl groups were confirmed by Fourier transform infrared spectroscopy (FTIR). The thermal stability of hydrophobic SiO2 NPs showed that the degradation of the alkyl groups takes place in the 200–400 °C range. Bilayer coating with C16TMS/TMOS and SiO2 NPs modified with alkoxysilane substituted with C8 alkyl chain (SiO2 NP-C8) has micro/nano structure. Hydrophobicity of functionalized SiO2 NPs-C8 and its higher degree of nanometer-scale roughness gave rise to ultra-hydrophobicity performance for bilayer coating C16TMS/TMOS + SiO2 NPs-C8 (145°), compared to other similar hybrid structures. Our synthesis method for the functionalization of SiO2 NPs is useful for the modification of surface polarity and roughness.

  3. The Influence of New Hydrophobic Silica Nanoparticles on the Surface Properties of the Films Obtained from Bilayer Hybrids

    Directory of Open Access Journals (Sweden)

    Cristian Petcu

    2017-02-01

    Full Text Available Ultra-hydrophobic bilayer coatings on a glass surface were fabricated by sol–gel process using hexadecyltrimethoxysilane (C16TMS and tetramethoxysilane (TMOS (1:4 molar ratio as precursors. After coating, silica nanoparticles (SiO2 NPs functionalized with different mono-alkoxy derivatives (methoxytrimethylsilane, TMeMS; ethoxydimethylvinylsilane, DMeVES; ethoxydimethylphenylsilane, DMePhES; and methoxydimethyloctylsilane, DMeC8MS were added, assuring the microscale roughness on the glass surface. Influences of the functionalized SiO2 NPs and surface morphology on the hydrophobicity of the hybrid films were discussed. The successful functionalization of SiO2 NPs with hydrophobic alkyl groups were confirmed by Fourier transform infrared spectroscopy (FTIR. The thermal stability of hydrophobic SiO2 NPs showed that the degradation of the alkyl groups takes place in the 200–400 °C range. Bilayer coating with C16TMS/TMOS and SiO2 NPs modified with alkoxysilane substituted with C8 alkyl chain (SiO2 NP-C8 has micro/nano structure. Hydrophobicity of functionalized SiO2 NPs-C8 and its higher degree of nanometer-scale roughness gave rise to ultra-hydrophobicity performance for bilayer coating C16TMS/TMOS + SiO2 NPs-C8 (145°, compared to other similar hybrid structures. Our synthesis method for the functionalization of SiO2 NPs is useful for the modification of surface polarity and roughness.

  4. Emerging photoluminescence from bilayer large-area 2D MoS2 films grown by pulsed laser deposition on different substrates

    Science.gov (United States)

    Barvat, Arun; Prakash, Nisha; Satpati, Biswarup; Singha, Shib Shankar; Kumar, Gaurav; Singh, Dilip K.; Dogra, Anjana; Khanna, Suraj P.; Singha, Achintya; Pal, Prabir

    2017-07-01

    We report the growth of continuous large area bilayer films of MoS2 on different substrates by pulsed laser deposition (PLD). The growth parameters for PLD were modified in such a way that results in bilayer 2D-MoS2 films on both c-Al2O3 (0001) (sapphire) and SiO2/Si (SO) substrates. The bilayer large area crystalline nature of growth in the 2 H-phase is determined by Raman spectroscopy. Cross-sectional transmission electron microscopy confirms the distinct thinnest ordered layered structure of MoS2. Chemical analysis reveals an almost stoichiometric 2 H-phase on both the substrates. The photoluminescence intensities of both the films match very well with those of the corresponding exfoliated flakes, as well as chemical vapor deposited (CVD) films as reported in the literature. The in-situ post growth annealing with optimal film thickness acts as a solid phase epitaxy process which provides continuous crystalline layers with a smooth interface and regulates the photoluminescence properties. In contrast, the PLD grown MoS2 monolayer shows poor crystalline quality and non-uniform coverage compared to that with the exfoliated and CVD grown films.

  5. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures

    Directory of Open Access Journals (Sweden)

    Jaydeep Bhattacharya

    2011-02-01

    Full Text Available Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic system for membrane fabrication and subsequent liposome fusion onto the nanoporous support structure. The resulting bilayer formation is monitored by impedance spectroscopy across the nanoporous alumina membrane in real-time. Our approach offers a simple and efficient methodology to investigate the activity of transmembrane proteins or ion diffusion across membrane bilayers.

  6. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures.

    Science.gov (United States)

    Bhattacharya, Jaydeep; Kisner, Alexandre; Offenhäusser, Andreas; Wolfrum, Bernhard

    2011-01-01

    Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic system for membrane fabrication and subsequent liposome fusion onto the nanoporous support structure. The resulting bilayer formation is monitored by impedance spectroscopy across the nanoporous alumina membrane in real-time. Our approach offers a simple and efficient methodology to investigate the activity of transmembrane proteins or ion diffusion across membrane bilayers.

  7. Physical properties of CuAlO 2 single crystal

    Science.gov (United States)

    Brahimi, R.; Bellal, B.; Bessekhouad, Y.; Bouguelia, A.; Trari, M.

    2008-09-01

    CuAlO 2 single crystal elaborated by the flux method is a narrow band gap semiconductor crystallizing in the delafossite structure (SG R3¯m). Oxygen insertion in the layered lattice generates p-type conductivity where most holes are trapped in surface-polaron states. The detailed photoelectrochemical characterization and electrochemical impedance spectroscopy (EIS) have been reported for the first time on the single crystal. The study is confined in the basal plan and reversible oxygen insertion is evidenced from the intensity potential characteristics. The oxide is characterized by an excellent chemical stability; the semi-logarithmic plot gave a corrosion potential of-0.82 V SCE and an exchange current density of 0.022 μA cm -2 in KCl (0.5 M) electrolyte. The capacitance measurement ( C-2- V) shows a linear behavior from which a flat band potential of +0.42 V SCE and a doping density NA of 10 16 cm -3 have been determined. The valence band, located at 5.24 eV (0.51 V SCE) below vacuum, is made up of Cu-3d orbital. The Nyquist plot exhibits a pseudo-semicircle whose center is localized below the real axis with an angle of 20°. This can be attributed to a single relaxation time of the electrical equivalent circuit and a constant phase element (CPE). The absence of straight line indicates that the process is under kinetic control.

  8. Templated assembly of Co-Pt nanoparticles via thermal and laser-induced dewetting of bilayer metal films.

    Science.gov (United States)

    Oh, Yong-Jun; Kim, Jung-Hwan; Thompson, Carl V; Ross, Caroline A

    2013-01-07

    Templated dewetting of a Co/Pt metal bilayer film on a topographic substrate was used to assemble arrays of Co-Pt alloy nanoparticles, with highly uniform particle size, shape and notably composition compared to nanoparticles formed on an untemplated substrate. Solid-state and liquid-state dewetting processes, using furnace annealing and laser irradiation respectively, were compared. Liquid state dewetting produced more uniform, conformal nanoparticles but they had a polycrystalline disordered fcc structure and relatively low magnetic coercivity. In contrast, solid state dewetting enabled formation of magnetically hard, ordered L1(0) Co-Pt single-crystal particles with coercivity >12 kOe. Furnace annealing converted the nanoparticles formed by liquid state dewetting into the L1(0) phase.

  9. Magnetic and electrical properties of CuFe2O4/BaTiO3 bilayer thin films

    Science.gov (United States)

    Yoon, Dong Jin; Hwang, Sung-Ok; Koo, Chang Young; Lee, Jai-Yeoul; Lee, Hee Young; Ryu, Jungho

    2013-04-01

    The magnetic and the electrical properties of CuFe2O4/BaTiO3 thin films grown on highly-textured Pt(111)/TiO2/SiO2/Si(100) substrates were studied. Sintered BaTiO3 and CuFe2O4 pellets prepared by the conventional mixed oxide process were used as targets during deposition by using the ion-beam sputtering and the pulsed laser deposition techniques. The film structure is of a bilayer type, where the BaTiO3 layer lies underneath the CuFe2O4 layer. The CuFe2O4/BaTiO3 film stack was then annealed at a temperature between 700 and 750 °C, followed by either FC (fast-cooling) or SC (slow-cooling) treatment. The ferroelectric and the electrical properties were measured using a ferroelectric test system, a digital multimeter, and an impedance analyzer. The Magnetic hysteresis (M-H) behavior at room temperature was measured using a vibration sample magnetometer (VSM), and the maximum saturation magnetization ( M s ) and coercivity ( H c ) values were 700 emu/cm3 and 325 Oe, respectively.

  10. Large-Scale Synthesis of a Uniform Film of Bilayer MoS2 on Graphene for 2D Heterostructure Phototransistors.

    Science.gov (United States)

    Chen, Chuanmeng; Feng, Zhihong; Feng, Yiyu; Yue, Yuchen; Qin, Chengqun; Zhang, Daihua; Feng, Wei

    2016-07-27

    The large-scale synthesis of atomically thin, layered MoS2/graphene heterostructures is of great interest in optoelectronic devices because of their unique properties. Herein, we present a scalable synthesis method to prepare centimeter-scale, continuous, and uniform films of bilayer MoS2 using low-pressure chemical vapor deposition. This growth process was utilized to assemble a heterostructure by growing large-scale uniform films of bilayer MoS2 on graphene (G-MoS2/graphene). Atomic force microscopy, Raman spectra, and transmission electron microscopy characterization demonstrated that the large-scale bilayer MoS2 film on graphene exhibited good thickness uniformity and a polycrystalline nature. A centimeter-scale phototransistor prepared using the G-MoS2/graphene heterostructure exhibited a high responsivity of 32 mA/W with good cycling stability; this value is 1 order of magnitude higher than that of transferred MoS2 on graphene (2.5 mA/W). This feature results from efficient charge transfer at the interface enabled by intimate contact between the grown bilayer MoS2 (G-MoS2) and graphene. The ability to integrate multilayer materials into atomically thin heterostructures paves the way for fabricating multifunctional devices by controlling their layer structure.

  11. Bilayer film electrode of brookite TiO2 particles with different morphology to improve the performance of pure brookite-based dye-sensitized solar cells

    Science.gov (United States)

    Xu, Jinlei; Wu, Shufang; Ri, Jin Hyok; Jin, Jingpeng; Peng, Tianyou

    2016-09-01

    A novel bilayer brookite TiO2 film photoanode consisting of quasi nanocube film as underlayer and rice-like submicrometer particle film as overlayer are fabricated for improving the photovoltaic properties of the pure brookite-based dye-sensitized solar cells (DSSCs). The brookite TiO2 nanocubes have a mean size of ∼50 nm, and the brookite TiO2 rice-like particles have diameter of ∼600 nm and length of ∼1100 nm. An optimal photovoltaic conversion efficiency of 5.51% is obtained from the bilayer brookite-based solar cell, with ∼41% improvement in the efficiency as compared to the single brookite nanocube film-based one (3.91%) under AM 1.5G one sun irradiation. The bilayer brookite-based solar cell shows not only reduced charge recombination and dark current, but also prolonged electron lifetime compared to the single brookite nanocube film-based one. All these lead to a higher photocurrent and voltage, and then to the improved efficiency of the brookite-based solar cell. The present results demonstrate a clear advance towards efficient improvement of the photovoltaic performance of pure brookite-based solar cells.

  12. 铁电双层膜的反转动力学行为%Switching dynamic b ehavior of a ferro electric bilayer film

    Institute of Scientific and Technical Information of China (English)

    崔莲; 邱忠阳; 李瑞英; 刘永皓; 李玉春; 夏遵义; 胡同瑞; 吕天全

    2014-01-01

    基于Landau-Khalatnikov运动方程,本文研究了含有表面过渡层和铁电界面耦合的反转动力学行为(包括平均极化、反转时间、反转电流和矫顽场)。研究结果表明:在铁电双层膜系统中存在一个竞争的机理,即表面过渡层与界面耦合的竞争作用。我们发现在双层膜反转过程中出现了反常行为,这些反常行为归因于表面过渡层与界面耦合之间的竞争。表面过渡层与界面耦合的共同行为对铁电双层膜的动力学特性起到了决定性的作用。%Based on the Landau-Khalatnikov equation of motion, the switching dynamic behaviors, (including the average polarization, switching time, switching current and coercive field) of a ferroelectric bilayer film with a surface transition layer within each constituent thin film and a ferroelectric interfacial coupling between two thin films have been inves-tigated. Results reveal that there is a competitive mechanism in the bilayer film, the action of surface transition layer and the interfacial coupling. The abnormal behavior is discovered in the polarization reversal process of the bilayer film, which can be attributed to the competition between the surface transition layer and the interfacial coupling. The combined action of surface transition layer and interfacial coupling plays a decisive role on the dynamic properties of a ferroelectric bilayer film.

  13. A comparative study of different M(M = Al, Ag, Cu)/FTO bilayer composite films irradiated with nanosecond pulsed laser

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Li-jing, E-mail: lij_huang@126.com [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); Ren, Nai-fei, E-mail: rnf_ujs@126.com [Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Bao-jia [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); Zhou, Ming [Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2014-12-25

    Highlights: • Different metal (i.e. Al, Ag and Cu) layers were sputtered on commercial FTO glass. • All the metal/FTO films were annealed by nanosecond pulsed laser irradiation. • Grating structures were also formed on the laser-irradiated Ag/FTO and Cu/FTO films. • The laser-irradiated Ag/FTO composite film had the better figure of merit. • Inducing gratings and annealing in one step is effective to improve film quality. - Abstract: Aluminium (Al), silver (Ag) and copper (Cu) layers were deposited on commercial fluorine-doped tin oxide (FTO) glass by direct current (DC) magnetron sputtering, so as to form Al/FTO, Ag/FTO and Cu/FTO bilayer films. Then all the as-deposited metal/FTO films were irradiated using a 532 nm nanosecond pulsed laser with a fluences of 1.05 J/cm{sup 2}. X-ray diffraction (XRD) analysis confirmed that all the laser-irradiated films were annealed by the laser and showed increased average crystallite size in FTO layers. Laser-induced grating structures were also obtained on the surfaces of the laser-irradiated Ag/FTO and Cu/FTO films, resulting in higher surface roughnesses and average transmittances of the films. But due to the broken continuity of the Ag and Cu layers, the sheet resistances of these two films slightly decreased as compared to that of the laser-irradiated Al/FTO film. It was also found that the laser-irradiated Ag/FTO film, whose average transmittance in 400–800 nm waveband and sheet resistance was 81.5% and 6.6 Ω/sq respectively, had the better figure of merit, indicating that the photoelectric property of FTO-based bilayer films could be further optimized through achieving fabrication of laser-induced grating structures and laser annealing in one step.

  14. On the determination of Poisson's ratio of stressed monolayer and bilayer submicron thick films

    CERN Document Server

    Martins, P; Brida, S; Barbier, D

    2008-01-01

    In this paper, the bulge test is used to determine the mechanical properties of very thin dielectric membranes. Commonly, this experimental method permits to determine the residual stress (s0) and biaxial Young's modulus (E/(1-u)). Associating square and rectangular membranes with different length to width ratios, the Poisson's ratio (u) can also be determined. LPCVD Si3N4 monolayer and Si3N4/SiO2 bilayer membranes, with thicknesses down to 100 nm, have been characterized giving results in agreement with literature for Si3N4, E = 212 $\\pm$ 14 GPa, s0 = 420 $\\pm$ 8 and u = 0.29.

  15. First principles study of CuAlO2 doping with S

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We study the electronic properties of CuAlO2 doped with S by the first principles calculations and find that the band gap of CuAlO2 is reduced after the doping.At the same time,the effective masses are also reduced and the density of states could cross the Fermi level.These results show that the conductivity of CuAlO2 could be enhanced by doping the impurities of S,which needs to be further studied.

  16. Effects of annealing time on the structure, morphology, and stress of gold-chromium bilayer film

    Science.gov (United States)

    Zhang, Hong; Jin, Yun-Xia; Wang, Hu; Kong, Fang-Yu; Huang, Hao-Peng; Cui, Yun

    2016-10-01

    In this work, a 200-nm-thick gold film with a 10-nm-thick chromium layer used as an adhesive layer is fabricated on fused silica by the electron beam evaporation method. The effects of annealing time at 300 °C on the structure, morphology and stress of the film are studied. We find that chromium could diffuse to the surface of the film by formatting a solid solution with gold during annealing. Meanwhile, chromium is oxidized on the surface and diffused downward along the grain grooves in the gold film. The various operant mechanisms that change the residual stresses of gold films for different annealing times are discussed. Project supported by the National Natural Science Foundation of China (Grant No. 61405225).

  17. Study of structure of the TiO{sub 2}–MoO{sub 3} bilayer films by Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Elias de Barros; Sigoli, Fernando Aparecido; Mazali, Italo Odone, E-mail: mazali@iqm.unicamp.br

    2014-12-15

    Highlights: • TiO{sub 2}–MoO{sub 3} bilayer thin films were easily prepared by dip-coating technique. • Ti and Mo metallo-organic compounds were used as source of its respective oxide. • TiO{sub 2} in anatase phase and orthorhombic phase of α-MoO{sub 3} were identified. • The bilayer structure was investigated by Raman spectroscopy. - Abstract: In this work, TiO{sub 2}–MoO{sub 3} films were easily prepared by dip-coating technique and metallo-organic decomposition process (MOD). Raman analyses indicate the formation of TiO{sub 2} in anatase phase and orthorhombic phase of α-MoO{sub 3}. It was observed that the Raman bands intensities attributed to TiO{sub 2} and MoO{sub 3} oxides were dependent on the number of decomposition–deposition cycles (DDC). The different number of DDC generates films with different thicknesses and the Raman signal was sensitive to this variation. Raman analyses provided qualitative information about the bilayer structure of the bi-component TiO{sub 2}–MoO{sub 3} films, which was confirmed by scanning electron microscopy. In this direction, the dip-coating technique and MOD process can be an efficient strategy to facile preparation of many samples to be used in applications.

  18. High performance nanocomposite thin film transistors with bilayer carbon nanotube-polythiophene active channel by ink-jet printing

    Science.gov (United States)

    Hsieh, Gen-Wen; Li, Flora M.; Beecher, Paul; Nathan, Arokia; Wu, Yiliang; Ong, Beng S.; Milne, William I.

    2009-12-01

    Nanocomposite thin film transistors (TFTs) based on nonpercolating networks of single-walled carbon nanotubes (CNTs) and polythiophene semiconductor [poly[5,5'-bis(3-dodecyl-2-thienyl)-2,2'-bithiophene] (PQT-12)] thin film hosts are demonstrated by ink-jet printing. A systematic study on the effect of CNT loading on the transistor performance and channel morphology is conducted. With an appropriate loading of CNTs into the active channel, ink-jet printed composite transistors show an effective hole mobility of 0.23 cm2 V-1 s-1, which is an enhancement of more than a factor of 7 over ink-jet printed pristine PQT-12 TFTs. In addition, these devices display reasonable on/off current ratio of 105-106, low off currents of the order of 10 pA, and a sharp subthreshold slope (polythiophene polymers and nonpercolating CNTs, where the CNT density in the bilayer structure substantially influences the morphology and transistor performance of polythiophene. Therefore, optimized loading of ink-jet printed CNTs is crucial to achieve device performance enhancement. High performance ink-jet printed nanocomposite TFTs can present a promising alternative to organic TFTs in printed electronic applications, including displays, sensors, radio-frequency identification (RFID) tags, and disposable electronics.

  19. Kinetic equation for internal oxidation of Cu-Al alloy cylinders

    Institute of Scientific and Technical Information of China (English)

    Kexing Song; Jiandong Xing; Baohong Tian; Ping Liu; Qiming Dong

    2005-01-01

    The kinetics of internal oxidation of Cu-Al alloy cylinders, containing up to 2.214mol% Al, were investigated in the temperature range of 1023 K to 1273 K, and the depth of internal oxidation was measured in the microscopy. A kinetic equation was derived to describe the internal oxidation of Cu-Al alloy cylinders. For the internal oxidation of Cu-Al alloys employed in the synthesis of alumina dispersion strengthened copper, the kinetic equation can be simplified. The derived equation was checked experimentally by means of oxidation depth measurements and the results show that the derived equation is exact enough to describe the kinetics of internal oxidation of Cu-Al alloy cylinders. Based on this equation and the oxidation depth measurements, the permeability of oxygen in solid copper was obtained. Investigation also shows that there is no evidence for preferential diffusion along grain boundaries in the process of internal oxidation.

  20. Natural and persistent superhydrophilicity of SiO{sub 2}/TiO{sub 2} and TiO{sub 2}/SiO{sub 2} bi-layer films

    Energy Technology Data Exchange (ETDEWEB)

    Permpoon, S.; Houmard, M. [Laboratoire de Thermodynamique et de Physico-Chimie Metallurgique, ENSEEG-INPG, BP 75, Domaine Universitaire, 38402 Saint Martin d' Heres (France); Laboratoire de Materiaux et de Genie Physique, ENSPG-INPG-MINATEC, 3 parvis Louis Neel, BP 257, 38016 Grenoble Cedex 1 (France); Riassetto, D.; Rapenne, L. [Laboratoire de Materiaux et de Genie Physique, ENSPG-INPG-MINATEC, 3 parvis Louis Neel, BP 257, 38016 Grenoble Cedex 1 (France); Berthome, G.; Baroux, B.; Joud, J.C. [Laboratoire de Thermodynamique et de Physico-Chimie Metallurgique, ENSEEG-INPG, BP 75, Domaine Universitaire, 38402 Saint Martin d' Heres (France); Langlet, M. [Laboratoire de Materiaux et de Genie Physique, ENSPG-INPG-MINATEC, 3 parvis Louis Neel, BP 257, 38016 Grenoble Cedex 1 (France)], E-mail: Michel.Langlet@inpg.fr

    2008-01-30

    Sol-gel SiO{sub 2}/TiO{sub 2} and TiO{sub 2}/SiO{sub 2} bi-layer films have been deposited from a polymeric SiO{sub 2} solution and either a polymeric TiO{sub 2} mother solution (MS) or a derived TiO{sub 2} crystalline suspension (CS). The chemical and structural properties of MS and CS bi-layer films heat-treated at 500 deg. C have been investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscospy. Water contact angle measurements show that MS SiO{sub 2}/TiO{sub 2} and CS TiO{sub 2}/SiO{sub 2} bi-layer films exhibit a natural superhydrophilicity, but cannot maintain a zero contact angle for a long time over film aging. In contrast, CS SiO{sub 2}/TiO{sub 2} bi-layer films exhibit a natural, persistent, and regenerable superhydrophilicity without the need of UV light. Superhydrophilic properties of bi-layer films are discussed with respect to the nature of the TiO{sub 2} single-layer component and arrangement of the bi-layer structure, i.e. TiO{sub 2} underlayer or overlayer.

  1. Cu2ZnSnSe4 thin-film solar cells fabricated using Cu2SnSe3 and ZnSe bilayers

    Science.gov (United States)

    Kim, Kang Min; Liao, Kuang Hsiang; Tampo, Hitoshi; Shibata, Hajime; Niki, Shigeru

    2015-04-01

    Evaporated Cu2SnSe3 (CTSe) and ZnSe bilayers are used as precursors for the fabrication of Cu2ZnSnSe4 (CZTSe) thin films. Large grains (i.e., >1 µm) in CZTSe were obtained at a relatively low annealing temperature of 500 °C. The stacking order of precursors strongly affected the chemical composition of CZTSe thin films even under identical growth conditions. Zn loss in CTSe/ZnSe/Mo precursors occurred during CTSe deposition, whereas ZnSe/CTSe/Mo precursors showed improved stability in composition. The CZTSe solar cells fabricated using ZnSe/CTSe bilayer precursors with annealing showed a conversion efficiency of over 7%.

  2. Effect of the preparation procedure on the morphology of thin TiO₂ films and their device performance in small-molecule bilayer hybrid solar cells.

    Science.gov (United States)

    Unger, Eva L; Spadavecchia, Francesca; Nonomura, Kazuteru; Palmgren, Pål; Cappelletti, Giuseppe; Hagfeldt, Anders; Johansson, Erik M J; Boschloo, Gerrit

    2012-11-01

    Flat titanium dioxide films, to be used as the acceptor layer in bilayer hybrid solar cell devices, were prepared by spray-pyrolysis and by spin-casting. Both preparation methods resulted in anatase titania films with similar optical and electronic properties but considerably different film morphologies. Spray pyrolysis resulted in dense TiO₂ films grown onto and affected by the surface roughness of the underlying conducting glass substrates. The spin-casting preparation procedure resulted in nanoporous titania films. Hybrid solar cell devices with varying layer thickness of the small-molecule semiconducting dye TDCV-TPA were investigated. Devices built with spray-pyrolyzed titania substrates yielded conversion efficiencies up to 0.47%. Spin-cast titania substrates exhibited short circuits for thin dye layer thickness. For thicker dye layers the performance of these devices was up to 0.6% due to the higher interfacial area for charge separation of these nanoporous TiO₂ substrates.

  3. Vacuum annealing phenomena in ultrathin TiDy/Pd bi-layer films evaporated on Si(100) as studied by TEM and XPS.

    Science.gov (United States)

    Lisowski, W; Keim, E G

    2010-04-01

    Using a combination of TEM and XPS, we made an analysis of the complex high-temperature annealing effect on ultrathin titanium deuteride (TiD(y)) films evaporated on a Si(100) substrate and covered by an ultrathin palladium layer. Both the preparation and annealing of the TiD(y)/Pd bi-layer films were performed in situ under UHV conditions. It was found that the surface and bulk morphology of the bi-layer film as well as that of the Si substrate material undergo a microstructural and chemical conversion after annealing and annealing-induced deuterium evolution from the TiD(y) phase. Energy-filtered TEM (EFTEM) mapping of cross-section images and argon ion sputter depth profiling XPS analysis revealed both a broad intermixing between the Ti and Pd layers and an extensive inter-diffusion of Si from the substrate into the film bulk area. Segregation of Ti at the Pd top layer surface was found to occur by means of angle-resolved XPS (ARXPS) and the EFTEM analyses. Selected area diffraction (SAD) and XPS provided evidence for the formation of a new PdTi(2) bimetallic phase within the top region of the annealed film. Moreover, these techniques allowed to detect the initial stages of TiSi phase formation within the film-substrate interlayer.

  4. Magnetic properties and structure of Ni80Fe20/Ni48Fe12Cr40 bilayer films deposited on SiO2/Si(100) by electron beam evaporation

    Institute of Scientific and Technical Information of China (English)

    WU Ping; GAO Yanqing; QIU Hong; PAN Liqing; TIAN Yue; Wang Fengping

    2007-01-01

    Ni80Fe20/Ni48Fe12Cr40 bilayer films and Ni80Fe20 monolayer films were deposited at room temperature on SiO2/Si(100) substrates by electron beam evaporation. The influence of the thickness of the Ni48Fe12Cr40underlayer on the structure, magnetization, and magnetoresistance of the Ni80Fe20/Ni48Fe12Cr40 bilayer film was investigated. The thickness of the Ni48Fe12Cr40 layer varied from about 1 nm to 18 nm while the Ni80Fe20 layer thickness was fixed at 45 nm. For the as-deposited bilayer films the introducing of the Ni48Fe12Cr40 underlayer promotes both the (111) texture and grain growth in the Ni80Fe20 layer. The Ni48Fe12Cr40 underlayer has no significant influence on the magnetic moment of the Ni80Fe20/Ni48Fe12Cr40 bilayer film. However, the coercivity of the bilayer film changes with the thickness of the Ni48Fe12Cr40underlayer. The optimum thickness of the Ni48Fe12Cr40 underlayer for improving the anisotropic magnetoresistance effect of the Ni80Fe20/Ni48Fe12Cr40 bilayer film is about 5 nm. With a decrease in temperature from 300 K to 81 K, the anisotropic magnetoresistance ratio of the Ni80Fe20 (45 nm)/Ni48Fe12Cr40 (5 nm) bilayer film increases linearly from 2.1% to 4.8% compared with that of the Ni80Fe20 monolayer film from 1.7% to 4.0%.

  5. First observation of sol-gel derived Al:CsZnO/CsZnO bilayer thin film for solar cells application

    Science.gov (United States)

    Ahmadi, Mehdi; Rashidi Dafeh, Sajjad; Alinazmabadi, Saeid

    2016-10-01

    In this research, we fabricated CsZnO and Al:CsZnO/CsZnO bilayer thin films grown by the spin-coating-assisted sol-gel method on ITO substrate. The influence of diverse velocity of spin-coating (500, 1000, 1500, 2000, 2500 and 3000RPM) and also annealing times (30, 60, 90, 120, 150 and 180min) on the characteristics of the ZnO thin film was examined. The samples were examined by X-ray diffraction, scanning electron microscopy, Uv-Vis spectrometer and conductivity measurement. With the optimization of the velocity of spin-coating (2500RPM) and annealing times (60min), we fabricated Al:CsZnO/CsZnO bilayer thin films with diverse dopant concentration. By comparing the effect of dopant concentration with different dopant ratio (0, 0.5, 1.0 and 2%), 0.5% of CsZnO and Al:CsZnO/CsZnO bilayer was found as the most effective doping level with the best conductivity properties among the selected doping concentrations.

  6. Developing high-transmittance heterojunction diodes based on NiO/TZO bilayer thin films.

    Science.gov (United States)

    Huang, Chia-Cheng; Wang, Fang-Hsing; Wu, Chia-Ching; Huang, Hong-Hsin; Yang, Cheng-Fu

    2013-05-01

    In this study, radio frequency magnetron sputtering was used to deposit nickel oxide thin films (NiO, deposition power of 100 W) and titanium-doped zinc oxide thin films (TZO, varying deposition powers) on glass substrates to form p(NiO)-n(TZO) heterojunction diodes with high transmittance. The structural, optical, and electrical properties of the TZO and NiO thin films and NiO/TZO heterojunction devices were investigated with scanning electron microscopy, X-ray diffraction (XRD) patterns, UV-visible spectroscopy, Hall effect analysis, and current-voltage (I-V) analysis. XRD analysis showed that only the (111) diffraction peak of NiO and the (002) and (004) diffraction peaks of TZO were observable in the NiO/TZO heterojunction devices, indicating that the TZO thin films showed a good c-axis orientation perpendicular to the glass substrates. When the sputtering deposition power for the TZO thin films was 100, 125, and 150 W, the I-V characteristics confirmed that a p-n junction characteristic was successfully formed in the NiO/TZO heterojunction devices. We show that the NiO/TZO heterojunction diode was dominated by the space-charge limited current theory.

  7. RAPID COMMUNICATION: ? thin film bilayers grown by pulsed laser ablation deposition

    Science.gov (United States)

    Singh, S. K.; Palmer, S. B.; McK Paul, D.; Lees, M. R.

    1996-09-01

    We have grown superconducting thin films of 0022-3727/29/9/044/img2 (Y-123) on 0022-3727/29/9/044/img3 (PCMO) buffer layers and PCMO overlayers on Y-123 thin films using pulsed laser ablation deposition. For both sets of films below 50 K, the Y-123 layer is superconducting and the zero-field cooled PCMO layer is insulating. The application of a magnetic field of 8 T results in an insulator - metal transition in the PCMO layer. This field-induced conducting state is stable in zero magnetic field at low temperature. The PCMO layer can be returned to an insulating state by annealing above 100 K. This opens the way for the construction of devices incorporating these oxide materials in which the electronic properties of key components such as the substrate or the barrier layer can be switched in a controlled way by the application of a magnetic field.

  8. Optical, electrical and thermoelectric power studies of Al–Sb thin film bilayer structure

    Indian Academy of Sciences (India)

    M Singh; J S Arora; Y K Vijay; M Sudharshan

    2006-02-01

    The III–V semiconductors are of great importance due to their applications in various electro-optic devices. The Al–Sb thin film was deposited on glass substrate by thermal evaporation method at a pressure of 10-5 torr. The samples were annealed for 3 h at different constant temperatures in a vacuum chamber at a pressure of 10-5 torr. The electrical resistance vs temperature studies show phase transformation from metallic to semiconducting. The observed positive thermoelectric power indicates that Al–Sb thin films are -type in nature. The Rutherford back scattering analysis and optical band gap measurements also indicate that the interdiffusion concentration varies with temperature.

  9. Resonance Effects of Bilayered Piezoelectric Films Used for Bulk Acoustic Wave Sensors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; ZHANG Shu-Yi; FAN Li

    2011-01-01

    The resonance vibrations of acoustic sensors with two layers of (1120) textured hexagonal piezoelectric films are studied.When the acoustic and electric fields satisfy a special match condition,i.e.the phase variation of thickness shear mode (TSM) at each film equals π,both piezoelectric layers with opposite polarization directions reduce the first TSM and generate the second TSM with higher frequency and a higher quality factor.The excited second TSM can increase the product of the operating frequency and the quality factor,which is useful for improving the mass sensitivity and resolution of acoustic sensors.Additionally,both of the piezoelectric films have larger thickness and decrease the risk of mechanical damage in device production processes.Thin film bulk acoustic sensors have attracted great attention due to their small sizes,low power consumption and high sensitivity,etc.[1] The thickness shear mode (TSM) is more suitable for liquid sensing applications since much less acoustic energy is transferred into the liquid medium than that of longitudinal acoustic waves,due to the fact that ideal liquids cannot support propagations of shear waves.By using a TSM with a high resonance frequency,sensorsbased on thin film bulk acoustic resonator structures can be fabricated by the fixing of a sensitive coating on the surface of the device.[2] The binding events at the sensitive coating can cause a shift of the resonance frequency.[3]%The resonance vibrations of acoustic sensors with two layers of (1120) textured hexagonal piezoelectric films are studied. When the acoustic and electric fields satisfy a special match condition, I.e. The phase variation of thickness shear mode (TSM) at each film equals it, both piezoelectric layers with opposite polarization directions reduce the first TSM and generate the second TSM with higher frequency and a higher quality factor. The excited second TSM can increase the product of the operating frequency and the quality factor, which

  10. Continuous determination of Cu, Al, Zn in Ag- Cu- Al- Zn quarternary alloy by titration%滴定法连续测定银铜铝锌四元合金中Cu,Al,Zn

    Institute of Scientific and Technical Information of China (English)

    麦丽碧

    2004-01-01

    采用连续滴定的方法同时测定Cu,Al,Zn.加入一定量的EDTA标准溶液,使Cu2+,Al3+,Zn2+全部与EDTA络合,用Zn2+盐滴定过量EDTA,然后加氟盐置换出EDTA-Al中的EDTA,用硫脲抗坏血酸和邻菲啰啉置换出EDTA-Cu中的EDTA,并分别用Zn2+盐滴定,从总量中减去Al量和Cu量即得Zn量.滴定Cu,Al,Zn回收率均在98%以上,本法分析快速准确.

  11. Preparation of ferroelectric bi-layered thin films using the modified polymeric precursor method

    Directory of Open Access Journals (Sweden)

    S.M. Zanetti

    2001-07-01

    Full Text Available The modified polymeric precursor method was used to synthesize ferroelectric bismuth-layered compounds such as, SrBi2Ta2O9 (SBT and SrBi2Nb2O9 (SBN. This method allows for the use of precursor reagents such as oxide, carbonate or nitrate as cation sources, with the additional advantage of not requiring special equipment for the synthesis. The films were deposited by spin coating on Pt/Ti/SiO2/Si(100 and SrTiO3(100 (STO substrates and crystallized at temperatures between 700 and 800 °C in the case of SBT films and 650 °C to 750 °C in that of SBN films. The crystallographic and microstructural characterizations were carried out by X-ray diffraction (XRD, scanning electron microscopy (SEM and atomic force microscopy (AFM. The ferroelectric and dielectric properties of the films indicate their applicability in ferroelectric memories and optical devices.

  12. Effect of Annealing Time Process on the pH Sensitivity of Spin-coated TiO2/ ZnO Bilayer Film

    Science.gov (United States)

    Rahman, R. A.; Zulkefle, M. A.; Yusof, K. A.; Abdullah, W. F. H.; Rusop, M.; Herman, S. H.

    2015-11-01

    This paper presents an investigation on titanium dioxide (TiO2) and zinc oxide (ZnO) bilayer film, which is used as sensing membrane for extended-gate field effect transistor (EGFET) for pH sensing application. TiO2/ZnO thin films were deposited using sol-gel spin coating method on indium tin oxide (ITO) substrates. After the deposition, the bilayer films were annealed at constant temperatures which is 400 °C for 15, 30, 40 and 60 minutes. The sensitivity of the TiO2 thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. By varying the annealing time, we found that the TiO2/ZnO thin film annealed at 400°C for 15 minutes gave the highest sensitivity compared to other annealing conditions, with the value of 64.87 mV/pH.

  13. Nanoscale magnetism and novel electronic properties of a bilayer bismuth(111) film with vacancies and chemical doping.

    Science.gov (United States)

    Sahoo, M P K; Zhang, Yajun; Wang, Jie

    2016-07-27

    Magnetically doped topological insulators (TIs) exhibit several exotic phenomena including the magnetoelectric effect and quantum anomalous Hall effect. However, from an experimental perspective, incorporation of spin moment into 3D TIs is still challenging. Thus, instead of 3D TIs, the 2D form of TIs may open up new opportunities to induce magnetism. Based on first principles calculations, we demonstrate a novel strategy to realize robust magnetism and exotic electronic properties in a 2D TI [bilayer Bi(111) film: abbreviated as Bi(111)]. We examine the magnetic and electronic properties of Bi(111) with defects such as bismuth monovacancies (MVs) and divacancies (DVs), and these defects decorated with 3d transition metals (TMs). It has been observed that the MV in Bi(111) can induce novel half metallicity with a net magnetic moment of 1 μB. The origin of half metallicity and magnetism in MV/Bi(111) is further explained by the passivation of the σ-dangling bonds near the defect site. Furthermore, in spite of the nonmagnetic nature of DVs, the TMs (V, Cr, Mn, and Fe) trapped at the 5/8/5 defect structure of DVs can not only yield a much higher spin moment than those trapped at the MVs but also display intriguing electronic properties such as metallic, semiconducting and spin gapless semiconducting properties. The predicted magnetic and electronic properties of TM/DV/Bi(111) systems are explained through density of states, spin density distribution and Bader charge analysis.

  14. Facile synthesis of dendritic Cu by electroless reaction of Cu-Al alloys in multiphase solution

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ying; Liang, Shuhua, E-mail: liangxaut@gmail.com; Yang, Qing; Wang, Xianhui

    2016-11-30

    Highlights: • Nano- or micro-scale fractal dendritic copper (FDC) was synthesized by electroless immersing of Cu-Al alloys in CuCl{sub 2} + HCl. • FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl{sub 2} + HCl solution. • Nanoscale Cu{sub 2}O was found at the edge of FDC. Nanoporous copper (NPC) can also be obtained by using Cu{sub 17}Al{sub 83} alloy. • The potential difference between CuAl{sub 2} and α-Al phase and the replacement reaction in multiphase solution are key factors. - Abstract: Two-dimensional nano- or micro-scale fractal dendritic coppers (FDCs) were synthesized by electroless immersing of Cu-Al alloys in hydrochloric acid solution containing copper chloride without any assistance of template or surfactant. The FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl{sub 2} + HCl solution. Compared to Cu{sub 40}Al{sub 60} and Cu{sub 45}Al{sub 55} alloys, the FDC shows hierarchical distribution and homogeneous structures using Cu{sub 17}Al{sub 83} alloy as the starting alloy. The growth direction of the FDC is <110>, and all angles between the trunks and branches are 60°. Nanoscale Cu{sub 2}O was found at the edge of FDC. Interestingly, nanoporous copper (NPC) can also be obtained through Cu{sub 17}Al{sub 83} alloy. Studies showed that the formation of FDC depended on two key factors: the potential difference between CuAl{sub 2} intermetallic and α-Al phase of dual-phase Cu-Al alloys; a replacement reaction that usually occurs in multiphase solution. The electrochemical experiment further proved that the multi-branch dendritic structure is very beneficial to the proton transfer in the process of catalyzing methanol.

  15. Influence of Tin Additions on the Phase-Transformation Characteristics of Mechanical Alloyed Cu-Al-Ni Shape-Memory Alloy

    Science.gov (United States)

    Saud, Safaa N.; Hamzah, E.; Abubakar, T.; Bakhsheshi-Rad, H. R.; Mohammed, M. N.

    2016-10-01

    The influence of the addition of Sn to Cu-Al-Ni alloy as a fourth element with different percentages of 0.5, 1.0, and 1.5 wt pct on the microstructure, phase-transformation temperatures, mechanical properties, and corrosion behaviors was investigated. The modified and unmodified alloys were fabricated by mechanical alloying followed by microwave sintering. The sintered and homogenized alloys of Cu-Al-Ni- xSn shape-memory alloys had a refined particle structure with an average particle size of 40 to 50 µm associated with an improvement in the mechanical properties and corrosion resistance. With the addition of Sn, the porosity density tends to decrease, which can also lead to improvements in the properties of the modified alloys. The minimum porosity percentage was observed in the Cu-Al-Ni-1.0 wt pct Sn alloy, which resulted in enhancing the ductility, strain recovery, and corrosion resistance. Further increasing the Sn addition to 1.5 wt pct, the strength of the alloy increased because the highest volume fraction of precipitates was formed. Regarding the corrosion behavior, addition of Sn up to 1 wt pct increased the corrosion resistance of the base SMA from 2.97 to 19.20 kΩ cm2 because of formation of a protective film that contains hydrated tin oxyhydroxide, aluminum dihydroxychloride, and copper chloride on the alloy. However, further addition of Sn reduced the corrosion resistance.

  16. Design optimization of cast Cu-Al-Be-B alloys for high clamping capacity

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    This paper investigated high-damping Cu-Al-Be-B cast alloys using metallographic analysis, X-ray diffraction (XRD) and electrical resistance measurements for transformation temperatures. The results showed that beryllium can stabilize β phase, resulting in a thermo-elastic martensite microstructure leading to high-damping capacity in cast Cu-Al-BeB alloys. Trace additions of boron to Cu-Al-Be alloys can significantly refine the grains, providing high strength and ductility to the alloys. A factorial design of experiment method was used to optimize the composition and properties of cast Cu-Al-BeB alloys. The optimal microstructure for thermo-elastic martensite can be obtained by adjusting the amounts of aluminum and beryllium to eutectoid or pseudo-eutectoid compositions. An optimized cast Cu-Al-Be-B alloy was developed to provide excellent mechanical properties, tensile strength σb = 767 MPa, elongation δ = 7.62 %, and damping capacity S. D.C =18.70%.

  17. Preparation of Copper (Cu)-Nickel (Ni) Alloy Thin Films for Bilayer Graphene Growth

    Science.gov (United States)

    2016-02-01

    10. SPONSOR/MONITOR’S ACRONYM(S) 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release... morphological changes in the metal surfaces such as roughness, grain size, and crystal orientation due to the effects of annealing temperature, hydrogen...Ni thin film a) sputtered at 5 mT and 25 °C and b) sputtered at 15 mT and 400 °C 3.2 Grain Growth Characterization The morphology of the as

  18. Reporting performance in MoS{sub 2}–TiO{sub 2} bilayer and heterojunction films based dye-sensitized photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    He, Zuoli, E-mail: wandaohzl@163.com; Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn; Xing, Yonglei; Liu, Xiaobin

    2016-07-05

    Three types of bilayer and heterojunction films photoanodes were designed and fabricated from green synthesized MoS{sub 2} and TiO{sub 2} nanoparticles (NPs), and then the dye-sensitized solar cells based on these various films photoanodes were investigated. Results demonstrated that layered semiconductor MoS{sub 2} could be a viable material candidate for solar cell applications due to its superior photoelectric characteristics. The DSSCs from the MoS{sub 2}@TiO{sub 2} heterojunction film photoanode exhibit the highest solar energy conversion efficiency of 6.02% under AM 1.5G simulated solar irradiation, which is 1.5 times higher than that of the cell from pure TiO{sub 2} film photoanode. MoS{sub 2}–TiO{sub 2} heterojunction at the interface helps MoS{sub 2} NPs to efficiently collect the photo-injected electrons from TiO{sub 2} NPs, thus reduce charge recombination at both the NPs-electrolyte and NPs-dye interfaces. These advantages together with collecting or transferring injected electrons abilities by combining the improved light absorption and the large dye-loading capacity of such structural NPs films, rendering the MoS{sub 2}–TiO{sub 2} composite photoelectrode superior potential for DSSCs applications. - Highlights: • MoS{sub 2} and TiO{sub 2} NPs were synthesized via green process using rape pollen grains as bio-templates. • DSSCs based on these various bilayer and heterojunction films photoanodes were investigated. • Enhanced η of MoS{sub 2}@TiO{sub 2} based DSSCs was related to its strong light adsorption ability. • The mechanism of electron transport in these various films photoanodes was proposed.

  19. Kinetic Equation for Internal Oxidation of Cu-Al Alloy Spheres

    Institute of Scientific and Technical Information of China (English)

    SONG Kexing; GAO Jianxin; XU Xiaofeng; LI Peiquan; TIAN Baohong; GUO Xiuhua

    2007-01-01

    The kinetics of internal oxidation of Cu-Al alloy spheres, containing up to 2.214% mole fraction Al was investigated in the temperature range 1 023 K to 1 273 K, and the depth of internal oxidation was measured in the microscopy. A kinetic equation was derived to describe the internal oxidation of Cu-Al alloy spheres, which was checked experimentally by means of oxidation depth measurements. The results show that the derived equation is exact enough to describe the kinetics of internal oxidation of Cu-Al alloy spheres.Based on this equation and the oxidation depth measurements, the permeability of oxygen in solid copper has been obtained. Investigation also shows that in the process of internal oxidation, there is no evidence for preferential diffusion along grain boundaries.

  20. Electron crystallography applied to the structure determination of Nb(Cu,Al,X) Laves phases.

    Science.gov (United States)

    Gigla, M; Lelatko, J; Krzelowski, M; Morawiec, H

    2006-09-01

    The presence of primary precipitates of the Laves phases considerably improves the mechanical properties and the resistance to thermal degradation of the high-temperature shape memory Cu-Al-Nb alloys. The structure analysis of the Laves phases was carried out on particles contained in the ternary and quaternary alloys as well on synthesized compounds related to the composition of the Nb(Cu,Al,X)(2) phase, where X = Ni, Co, Cr, Ti and Zr. The precise structure determination of the Laves phases was carried out by the electron crystallography method using the CRISP software.

  1. Synthesis, Structure, and Physical Properties of Ln(Cu,Al,Ga)13-x (Ln = La-Pr, and Eu) and Eu(Cu,Al)13-x

    Energy Technology Data Exchange (ETDEWEB)

    Phelan, W Adam; Kangas, Michael J; McCandless, Gregory T; Drake, Brenton L; Haldolaarachchige, Neel; Zhao, Liang L; Wang, Jiakui K; Wang, Xiaoping P; Young, David P; Morosan, Emilia; Hoffmann, Christina; Chan, Julia Y [LSU; (Rice); (ORNL)

    2012-09-10

    Ln(Cu,Al,Ga)13–x (Ln = La–Pr, and Eu; x ~ 0.2) were synthesized by a combined Al/Ga flux. Single crystal X-ray and neutron diffraction experiments revealed that these compounds crystallize in the NaZn13 structure-type (space group Fm3⁻c) with lattice parameters of a ~ 12 Å, V ~ 1600 Å, and Z ~ 8. Our final neutron models led us to conclude that Cu is occupationally disordered on the 8b Wyckoff site while Cu, Al, and Ga are substitutionally disordered on the 96i Wyckoff site of this well-known structure-type. The magnetic susceptibility data show that Ce(Cu,Al,Ga)13–x and Pr(Cu,Al,Ga)13–x exhibit paramagnetic behavior down to the lowest temperatures measured while Eu(Cu,Al,Ga)13–x displays ferromagnetic behavior below 6 K. Eu(Cu,Al)13–x was prepared via arc-melting and orders ferromagnetically below 8 K. The magnetocaloric properties of Eu(Cu,Al,Ga)13–x and Eu(Cu,Al)13–x were measured and compared. Additionally, an enhanced value of the Sommerfeld coefficient (γ = 356 mJ/mol-K2) was determined for Pr(Cu,Al,Ga)13–x. Herein, we present the synthesis, structural refinement details, and physical properties of Ln(Cu,Al,Ga)13–x (Ln = La–Pr, and Eu) and Eu(Cu,Al)13–x.

  2. Growth and magnetic properties of ultrathin epitaxial FeO films and Fe/FeO bilayers on MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Kozioł-Rachwał, A., E-mail: akoziol@agh.edu.pl [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Ślęzak, T. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Nozaki, T.; Yuasa, S. [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Korecki, J. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland)

    2016-01-25

    Ultrathin FeO(001) films were grown via molecular beam epitaxy on MgO(001) using reactive deposition of Fe. The growth conditions were adjusted toward stabilization of the wüstite phase, the existence of which was confirmed by means of conversion electron Mössbauer spectroscopy. It was shown how the metallic Fe overlayer modified the chemical state and the magnetic properties of the FeO oxide. Finally, we observed the exchange bias for an epitaxial Fe/FeO bilayer grown on MgO(001)

  3. Ti/Cu bilayer electrodes for SiNx-passivated Hf-In-Zn-O thin film transistors: Device performance and contact resistance

    Science.gov (United States)

    Park, Joon Seok; Kim, Tae Sang; Son, Kyoung Seok; Lee, Eunha; Jung, Ji Sim; Lee, Kwang-Hee; Maeng, Wan-Joo; Kim, Hyun-Suk; Kim, Eok Su; Park, Kyung-Bae; Kwon, Jang-Yeon; Ryu, Myung Kwan; Lee, Sang Yoon

    2010-10-01

    In this study, we examine the possibility of using Ti/Cu bilayer as source/drain electrodes for SiNx-passivated Hf-In-Zn-O (HIZO) thin film transistors by comparing their electrical properties with devices that use Mo electrodes. The Mo devices operate in depletion mode with a higher field effect mobility, while the Ti/Cu devices exhibit an improved subthreshold swing and operate in enhancement mode. Transmission electron microscopy characterization reveals the formation of an amorphous TiOx layer at the Ti/HIZO interface, which is suggested to be responsible for the disparate device characteristics in terms of contact resistance and threshold delay.

  4. Improvement in reliability of amorphous indium-gallium-zinc oxide thin-film transistors with Teflon/SiO2 bilayer passivation under gate bias stress

    Science.gov (United States)

    Fan, Ching-Lin; Tseng, Fan-Ping; Li, Bo-Jyun; Lin, Yu-Zuo; Wang, Shea-Jue; Lee, Win-Der; Huang, Bohr-Ran

    2016-02-01

    The reliability of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with Teflon/SiO2 bilayer passivation prepared under positive and negative gate bias stresses (PGBS and NGBS, respectively) was investigated. Heavier electrical degradation was observed under PGBS than under NGBS, indicating that the environmental effects under PGBS are more evident than those under NGBS. The device with bilayer passivation under PGBS shows two-step degradation. The positive threshold voltage shifts during the initial stressing period (before 500 s), owing to the charges trapped in the gate insulator or at the gate insulator/a-IGZO active layer interface. The negative threshold voltage shift accompanies the increase in subthreshold swing (SS) for the continuous stressing period (after 500 s) owing to H2O molecules from ambience diffused within the a-IGZO TFTs. It is believed that Teflon/SiO2 bilayer passivation can effectively improve the reliability of the a-IGZO TFTs without passivation even though the devices are stressed under gate bias.

  5. Thin metal bilayer for surface plasmon resonance sensors in a multimode plastic optical fiber: the case of palladium and gold metal films

    Science.gov (United States)

    Cennamo, Nunzio; Zuppella, Paola; Bacco, Davide; Corso, Alain J.; Pelizzo, Maria G.; Pesavento, Maria; Zeni, Luigi

    2016-05-01

    A novel sensing platform based on thin metal bilayer for surface plasmon resonance (SPR) in a D-shaped plastic optical fiber (POF) has been designed, implemented and tested. The experimental results are congruent with the numerical studies. This platform has been properly optimized to work in the 1.38 -1.42 refractive index range and it exhibits excellent sensitivity. This refractive index range is very interesting for bio-chemical applications, where the polymer layer are used as receptors (e.g. molecularly imprinted polymer) or to immobilize the bio-receptor on the metal surface. The proposed metallic bilayer is based on palladium and gold films and replaces the traditional gold by exhibiting higher performances. Furthermore, the deposition of the thin bilayer is a single process and no further manufacturing step is required. In fact, in this case the photoresist buffer layer between the POF core and the metal layer, usually required to increase the refractive index range, is no longer necessary.

  6. Leakage current transport mechanisms of La0.67Sr0.33MnO3/BaTiO3 bilayer films grown on Nb:SrTiO3

    Indian Academy of Sciences (India)

    Pan Ruikun; Liu Panke; Li Mingkai; Tao Haizheng; Li Pai; He Yunbin

    2015-06-01

    La0.67Sr0.33MnO3/BaTiO3(LSMO/BTO) bilayer films were epitaxially grown on Nb:SrTiO3 (NSTO) substrates by the pulsed laser deposition technique. Current–voltage (–) characteristics of the LSMO/BTO bilayer films were studied. – curves were measured at room temperature, which show rectifying behaviour and can be well fitted by the space-charge-limited current mechanism under forward bias while thermionic emission model under reverse bias. Analysis indicates that a modulating Schottky barrier exists at the LSMO/BTO interface, which dominates the leakage current transport properties of LSMO/BTO bilayer films.

  7. Mechanical properties of intermetallics formed during thermal aging of Cu-Al ball bonds

    NARCIS (Netherlands)

    Kouters, M.H.M.; Gubbels, G.H.M.; O'Halloran, O.; Rongen, R.; Weltevreden, E.R.

    2011-01-01

    In high power automotive electronics copper wire bonding is regarded as most promising alternative for gold wire bonding in 1st level interconnects and therefore subjected to severe functional requirements. In the Cu-Al ball bond interface the growth of intermetallic compounds may deteriorate the

  8. Elimination of formaldehyde over Cu-Al2O3 catalyst at room temperature.

    Science.gov (United States)

    Zhang, Chang-Bin; Shi, Xiao-Yan; Gao, Hong-Wei; He, Hong

    2005-01-01

    Catalytic elimination of formaldehyde (HCHO) was investigated over Cu-Al2O3 catalyst at room temperature. The results indicated that no oxidation of HCHO into CO2 occurs at room temperature, but the adsorption of HCHO occurs on the catalyst surface. With the increase of gas hourly space velocity (GHSV) and inlet HCHO concentration, the time to reach saturation was shortened proportionally. The results of the in situ DRIFTS, Density functional theory calculations and temperature programmed desorption(TPD) showed that HCHO was completely oxidized into HCOOH over Cu-Al2O3 at room temperature. With increasing the temperature in a flow of helium, HCOOH was completely decomposed into CO2 over the catalyst surface, and the deactivated Cu-Al2O3 is regenerated at the same time. In addition, although Cu had no obvious influence on the adsorption of HCHO on Al2O3, Cu dramatically lowered the decomposition temperature of HCOOH into CO2. It was shown that Cu-Al2O3 catalyst had a good ability for the removal of HCHO, and appeared to be promising for its application in destroying HCHO at room temperature.

  9. Facile synthesis of dendritic Cu by electroless reaction of Cu-Al alloys in multiphase solution

    Science.gov (United States)

    Wang, Ying; Liang, Shuhua; Yang, Qing; Wang, Xianhui

    2016-11-01

    Two-dimensional nano- or micro-scale fractal dendritic coppers (FDCs) were synthesized by electroless immersing of Cu-Al alloys in hydrochloric acid solution containing copper chloride without any assistance of template or surfactant. The FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl2 + HCl solution. Compared to Cu40Al60 and Cu45Al55 alloys, the FDC shows hierarchical distribution and homogeneous structures using Cu17Al83 alloy as the starting alloy. The growth direction of the FDC is , and all angles between the trunks and branches are 60°. Nanoscale Cu2O was found at the edge of FDC. Interestingly, nanoporous copper (NPC) can also be obtained through Cu17Al83 alloy. Studies showed that the formation of FDC depended on two key factors: the potential difference between CuAl2 intermetallic and α-Al phase of dual-phase Cu-Al alloys; a replacement reaction that usually occurs in multiphase solution. The electrochemical experiment further proved that the multi-branch dendritic structure is very beneficial to the proton transfer in the process of catalyzing methanol.

  10. Mechanical properties of intermetallics formed during thermal aging of Cu-Al ball bonds

    NARCIS (Netherlands)

    Kouters, M.H.M.; Gubbels, G.H.M.; O'Halloran, O.; Rongen, R.; Weltevreden, E.R.

    2011-01-01

    In high power automotive electronics copper wire bonding is regarded as most promising alternative for gold wire bonding in 1st level interconnects and therefore subjected to severe functional requirements. In the Cu-Al ball bond interface the growth of intermetallic compounds may deteriorate the wi

  11. Elimination of formaldehyde over Cu-Al2O3 catalyst at room temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chang-bin; SHI Xiao-yan; GAO Hong-wei; HE Hong

    2005-01-01

    Catalytic elimination of formaldehyde(HCHO) was investigated over Cu-Al2O3 catalyst at room temperature. The results indicated that no oxidation of HCHO into CO2 occurs at room temperature, but the adsorption of HCHO occurs on the catalyst surface.With the increase of gas hourly space velocity (GHSV) and inlet HCHO concentration, the time to reach saturation was shortened proportionally. The results of the in situ DRIFTS, Density functional theory calculations and temperature programmed desorption(TPD)showed that HCHO was completely oxidized into HCOOH over Cu-Al2 O3 at room temperature. With increasing the temperature in a flow of helium, HCOOH was completely decomposed into CO2 over the catalyst surface, and the deactivated Cu-Al2 O3 is regenerated at the same time. In addition, although Cu had no obvious influence on the adsorption of HCHO on Al2 O3, Cu dramatically lowered the decomposition temperature of HCOOH into CO2. It was shown that Cu-Al2 O3 catalyst had a good ability for the removal of HCHO, and appeared to be promising for its application in destroying HCHO at room temperature.

  12. Strong excitonic effects in CuAlO2 delafossite transparent conductive oxides

    DEFF Research Database (Denmark)

    Laskowski, Robert; Christensen, Niels Egede; Blaha, Peter;

    2009-01-01

    The imaginary part of the dielectric function of CuAlO2 has been calculated including the electron-hole correlation effects within Bethe-Salpeter formalism (BSE). In the initial step of the BSE solver the band structure was calculated within density-functional theory plus an orbital field (LDA...

  13. Optical behavior of the conjugated polymer MEH-PPV thin films stretched in bi-layer dwetting by an unstable layer

    Science.gov (United States)

    Chen, Po-Tsun; Yang, Arnold C.-M.

    2012-02-01

    Molecular packing and chain conformation play important roles in the optoelectronic performance of conjugated polymer thin films. It has been shown that by virtue of stretching via dewetting, the photoluminescence (PL) efficiencies of rarefied MEH-PPV thin films may be dramatically enhanced. To result similar effects in the stable non-diluted pristine MEH-PPV thin films, bi-layer dewetting was attempted in samples of MEH-PPV thin films (˜7nm) covered by one layer of polystyrene (PS) (˜40nm) that dewetted in toluene vapor to form droplets (height ˜300 nm) and ultrathin residual layer (˜3nm) on the substrate. The instability was initiated from the PS layer in which small pinholes first emerged upon the intake of the solvent vapor. The pinholes then expanded and deepened into the underlying MEH-PPV, forcing the conjugated film to dewet. As a result of the stretching induced by the dewetting, the PL peak blue-shifted 20 nm to 540 nm and the intensity was enhanced around 10 times. Revealed by the position-sensitive confocal PL data, the huge enhancement came from both the droplet and residual layer, caused by molecular separation and stretching. Electroluminescence devices are being made based on these stretched MEH-PPV films.

  14. Studies on the pyroelectric properties of ferroelectric bilayer film%铁电薄膜热释电性质的研究

    Institute of Scientific and Technical Information of China (English)

    张芹; 董亚男; 陈红

    2013-01-01

    Using Ginzburg-Landau-Devonshire theory, a ferroelectric bilayer film consisting of two different ferroelectric constituent films with the transition layer within each constituent film is considered. Introduced a parameter,which described the differences of physical properties between two constituent films, to investigate the temperature dependence of the pyroelectric coefficient of the bilayer film. It is shown that one or two peaks can be obtained in the pyroelectric curve by the adjustment of parameter Q. The modification of ferroelectric interfacial coupling cofficient,parameter a and surficial transition layer parameter leads to the peaks of the pyroelectric curve shifting to the higher or lower temperature region.%利用Ginzburg-Landau-Devonshire (GLD)热力学唯象理论,对由2种不同铁电材料构成的含有表面过渡层的铁电双层膜体系进行了探讨.通过引入一个描述2种铁电材料物理性能差异大小的物理参量α,并考虑2种铁电材料物理性能的差异,研究了铁电双层膜的热释电性质.结果表明:通过控制参量α的大小,热释电曲线上会呈现1个或2个峰;改变铁电界面耦合系数、参量α以及表面过渡层参量的大小,热释电曲线的峰位向高温区或低温区移动.

  15. Highly ordered monolayer/bilayer TiO2 hollow sphere films with widely tunable visible-light reflection and absorption bands

    Science.gov (United States)

    Li, Jie; Qin, Yao; Jin, Chao; Li, Ying; Shi, Donglu; Schmidt-Mende, Lukas; Gan, Lihua; Yang, Jinhu

    2013-05-01

    Monolayer and bilayer TiO2 hollow hemisphere/sphere (THH/THS) films consisting of highly ordered hexagonal-patterned THHs/THSs with thin shells of ~10 nm and different diameters of ~170 and ~470 nm have been prepared by templating of two-dimensional polystyrene sphere (PS) assembly films coupled with TiO2 sputtering/wet coating approaches. Owing to their precisely adjustable structural parameters, such as THH/THS shape and diameter as well as film layer thickness, the prepared THH/THS films exhibit widely tunable visible-light reflection and absorption bands, i.e. from 380 to 850 nm for reflection and 390 to 520 nm for absorption, respectively. The mechanism of the novel optical behaviors of the THH/THS films has been discussed in depth, combined with some calculations according to Bragg's law. In addition, photocatalytic experiments of RhB degradation employing the THH/THS films as recyclable catalysts have been conducted. The THH/THS films with controlled structures and precisely tunable optical properties are attractive for a wide range of applications, such as recyclable catalysts for photocatalysis, efficient oxide electrodes or scattering layers for solar cells, gas-permeable electrode materials for high-performance sensors and so on.Monolayer and bilayer TiO2 hollow hemisphere/sphere (THH/THS) films consisting of highly ordered hexagonal-patterned THHs/THSs with thin shells of ~10 nm and different diameters of ~170 and ~470 nm have been prepared by templating of two-dimensional polystyrene sphere (PS) assembly films coupled with TiO2 sputtering/wet coating approaches. Owing to their precisely adjustable structural parameters, such as THH/THS shape and diameter as well as film layer thickness, the prepared THH/THS films exhibit widely tunable visible-light reflection and absorption bands, i.e. from 380 to 850 nm for reflection and 390 to 520 nm for absorption, respectively. The mechanism of the novel optical behaviors of the THH/THS films has been discussed

  16. Effect of the diameter on Cu-Al post retention Efeito do diâmetro na retenção de pinos de Cu-Al

    OpenAIRE

    Celso Bernardo de Souza Filho; Silvana Maria Paulino; Edson Alfredo; Manoel Damião de Sousa Neto; Luiz Pascoal Vansan

    2004-01-01

    This study compared the resistance to removal by traction of abraded cylindrical metal cast posts of Cu-Al (Goldent-LA). The posts had constant length (9 mm) and three different diameters (0.9, 1.3 and 1.7 mm), and were cemented with zinc phosphate cement. The crowns of 36 sound maxillary canines were sectioned, the roots were immersed in resin blocks and the root canals were endodontically treated. The teeth were divided into three groups to be prepared and standardized with the use of a par...

  17. Slurry spin coating of thin film yttria stabilized zirconia/gadolinia doped ceria bi-layer electrolytes for solid oxide fuel cells

    Science.gov (United States)

    Kim, Hyun Joong; Kim, Manjin; Neoh, Ke Chean; Han, Gwon Deok; Bae, Kiho; Shin, Jong Mok; Kim, Gyu-Tae; Shim, Joon Hyung

    2016-09-01

    Thin ceramic bi-layered membrane comprising yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC) is fabricated by the cost-effective slurry spin coating technique, and it is evaluated as an electrolyte of solid oxide fuel cells (SOFCs). It is demonstrated that the slurry spin coating method is capable of fabricating porous ceramic films by adjusting the content of ethyl-cellulose binders in the source slurry. The porous GDC layer deposited by spin coating under an optimal condition functions satisfactorily as a cathode-electrolyte interlayer in the test SOFC stack. A 2-μm-thick electrolyte membrane of the spin-coated YSZ/GDC bi-layer is successfully deposited as a dense and stable film directly on a porous NiO-YSZ anode support without any interlayers, and the SOFC produces power output over 200 mW cm-2 at 600 °C, with an open circuit voltage close to 1 V. Electrochemical impedance spectra analysis is conducted to evaluate the performance of the fuel cell components in relation with the microstructure of the spin-coated layers.

  18. Grain size and temperature influence on the toughness of a CuAlBe shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Victor Hugo C. de, E-mail: victor.albuquerque@fe.up.pt [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Melo, Tadeu Antonio de A, E-mail: tadeu@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Gomes, Rodinei M., E-mail: gomes@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Lima, Severino Jackson G. de, E-mail: jackson@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Tavares, Joao Manuel R.S., E-mail: tavares@fe.up.pt [Faculdade de Engenharia da Universidade do Porto (FEUP), Departamento de Engenharia Mecanica (DEMec)/Instituto de Engenharia Mecanica e Gestao Industrial INEGI, Rua Dr. Roberto Frias, S/N 4200-465 Porto (Portugal)

    2010-11-25

    Research highlights: {yields} This work evaluated the capacity of a CuAlBe alloy to absorb energy until rupture. {yields} The V-notch Charpy test was adopted at -150, -100, -50, 0, 50, 100 and 150 deg. C. {yields} Charpy tests were complemented by DSC, DSC with optical microscope and by SEM. {yields} First work to analyze the toughness of a CuAlBe alloy based on the Charpy test. {yields} The results are of relevant value to enhance the understanding of the CuAlBe alloy. - Abstract: This work is a study of the influence of grain size and temperature on the toughness of CuAlBe shape memory alloys with (CuAlBeNbNi) and without NbNi (CuAlBe) grain refiner elements. The toughness analysis was based on the V-notch Charpy impact test under temperatures of -150, -100, -50, 0, 50, 100 and 150 deg. C. A statistical analysis of the results led to the conclusion that the toughness of both alloys was influenced by temperature and grain size. The CuAlBeNbNi alloy absorbed higher impact energy than the CuAlBe alloy showing that the refining elements improved the toughness of the alloy. To confirm and complement these findings, the fracture surfaces were evaluated by stereomicroscopy. Smooth homogeneous surfaces and rough heterogonous surfaces were detected for the CuAlBeNbNi and CuAlBe alloys, respectively. Predominately brittle zones were confirmed by scanning electron microscopy in both alloys. Furthermore, to determine the phase transformation temperatures and the associated microstructures, the alloys were assessed by conventional differential scanning calorimetry (DSC) and DSC with optical microscopy.

  19. Preparation and Properties of Plasma Spraying Cu-Al2O3 Gradient Coatings

    Institute of Scientific and Technical Information of China (English)

    Ali LEI; Nan DONG; Lajun FENG

    2007-01-01

    In order to overcome the limitations of low adhesion strength and poor thermal-shock resistance of pure ceramic coatings, Cu-Al2O3 gradient coatings were fabricated by plasma spraying. The microstructure and distribution of Cu-Al2O3 gradient coatings were analyzed. The adhesion strength, thermal-shock resistance and porosity of the coatings were tested. The results show that the composition of the gradient coatings has a gradient distribution along the thickness of coatings. As copper has a relatively low melting point and the molten copper has good wettability on the surface of Al2O3, it can be melted sufficiently and could fill the interstices and pores among the spraying particles effectively, thus improves the adhesion strength, thermal shock resistance and reduces the porosity. The adhesion strength of the gradient coating is 15.2 MPa which is two times of that of the double-layer structure coating.

  20. CARACTERIZATION OF Cu-Al-Mn ALLOYS FABRICATED USING ARC FURNACE

    Directory of Open Access Journals (Sweden)

    Diego E. Velázquez

    2016-06-01

    Full Text Available Two alloys of Cu-Al-Mn fabricated using an arc furnace built at the Instituto de Física de Materiales Tandil (IFIMAT were studied. The manufacture of alloys containing Mn is difficult, due to their high melting point and its low vapor pressure. Moreover, Mn at high temperature easily reacts with the materials used to build crucibles or capsules. In the casting arc difficulties arise to prevent volatilization, so it is very important the choice of electrode, the source setting, cooling, and the arrangement of the pure materials into the crucible. Critical temperatures of martensitic transformation and order were determined by Differential Scanning Calorimetry (DSC. Using Optical Microscopy (OM the presence of martensite phase was determined. From the results obtained it is concluded that this method is suitable for producing Cu-Al-Mn alloys.

  1. Electronic properties of 3R-CuAlO2 under pressure: Three theoretical approaches

    DEFF Research Database (Denmark)

    Christensen, Niels Egede; Svane, Axel; Laskowski, R.;

    2010-01-01

    -consistent GW"(QSGW) approximation. The structural parameters obtained by the LDA agree very well with experiments but, as expected, gaps in the formal band structure are underestimated as compared to optical experiments. The (in LDA too high lying) Cu 3d states can be down shifted by LDA+U. The magnitude......The pressure variation in the structural parameters, u and cla, of the delafossite CuAlO2 is calculated within the local-density approximation (LDA). Further, the electronic structures as obtained by different approximations are compared: LDA, LDA+U, and a recently developed "quasiparticle self...... values for some of the band-gap deformation potentials but calculations within both approximations predict that 3R-CuAlO2 remains an indirect-gap semiconductor at all pressures in its stability range 0-36 GPa, although the smallest direct gap has a negative pressure coefficient....

  2. Study of CuAl(100) by using He ion scattering

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, L.; Zur Muhlen, E.; O`Connor, D.J. [Newcastle Univ., NSW (Australia). Dept. of Physics

    1993-12-31

    The clean CuAl (100) surface has been investigated by using He{sup +} ion scattering. The polar scans show that Al atoms randomly replace the Cu atoms but sit (0.15{+-}0.05) Angstroms higher than the Cu atoms. The outmost layer concentration of Al is about (17{+-}3)%. The aluminium concentration on the outmost layer is sensitive to the sample temperature up to 300 deg C. 7 refs., 5 figs.

  3. Relationship between microstructure, cytotoxicity and corrosion properties of a Cu-Al-Ni shape memory alloy.

    Science.gov (United States)

    Colić, Miodrag; Rudolf, Rebeka; Stamenković, Dragoslav; Anzel, Ivan; Vucević, Dragana; Jenko, Monika; Lazić, Vojkan; Lojen, Gorazd

    2010-01-01

    Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but their biomedical application is still limited. The aim of this work was to compare the microstructure, corrosion and cytotoxicity in vitro of a Cu-Al-Ni SMA. Rapidly solidified (RS) thin ribbons, manufactured via melt spinning, were used for the tests. The control alloy was a permanent mould casting of the same composition, but without shape memory effect. The results show that RS ribbons are significantly more resistant to corrosion compared with the control alloy, as judged by the lesser release of Cu and Ni into the conditioning medium. These results correlate with the finding that RS ribbons were not cytotoxic to L929 mouse fibroblasts and rat thymocytes. In addition, the RS ribbon conditioning medium inhibited cellular proliferation and IL-2 production by activated rat splenocytes to a much lesser extent. The inhibitory effects were almost completely abolished by conditioning the RS ribbons in culture medium for 4 weeks. Microstructural analysis showed that RS ribbons are martensitic, with boron particles as a minor phase. In contrast, the control Cu-Al-Ni alloy had a complex multiphase microstructure. Examination of the alloy surfaces after conditioning by energy dispersive X-ray and Auger electron spectroscopy showed the formation of Cu and Al oxide layers and confirmed that the metals in RS ribbons are less susceptible to oxidation and corrosion compared with the control alloy. In conclusion, these results suggest that rapid solidification significantly improves the corrosion stability and biocompatibility in vitro of Cu-Al-Ni SMA ribbons.

  4. Diffusion and interface controlled reactions in {alpha}-(Cu-Al-Ag) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, A.T. [Instituto de Quimica, Unesp, Departamento de Fisico-Quimica, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil)]. E-mail: atadorno@iq.unesp.br; Silva, R.A.G. [Instituto de Quimica, Unesp, Departamento de Fisico-Quimica, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil); Magdalena, A.G. [Instituto de Quimica, Unesp, Departamento de Fisico-Quimica, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil)

    2007-08-30

    The isothermal kinetics of Ag precipitation was studied in Cu-Al-Ag alloys with concentrations ranging from 2 to 8 wt.%Al and 2 to 12 wt.%Ag, using scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDX) and microhardness measurements. The results indicated a change in the precipitates growing mechanism from diffusion to interface controlled process, probably due to a change in the nature of the interface with the Ag and Al enrichment of the precipitates.

  5. Cu-Al-Ni Shape Memory Single Crystal Wires with High Transformation Temperature

    Science.gov (United States)

    Hautcoeur, Alain; Fouché, Florian; Sicre, Jacques

    2016-01-01

    CN-250X is a new material with higher performance than Nickel-Titanium Shape Memory Alloy (SMA). For space mechanisms, the main disadvantage of Nickel-Titanium Shape Memory Alloy is the limited transformation temperature. The new CN-250X Nimesis alloy is a Cu-Al-Ni single crystal wire available in large quantity because of a new industrial process. The triggering of actuators made with this Cu-Al-Ni single crystal wire can range from ambient temperature to 200 C in cycling and even to 250 C in one-shot mode. Another advantage of CN-250X is a better shape recovery (8 to 10%) than Ni-Ti (6 to 7%). Nimesis is the first company able to produce this type of material with its new special industrial process. A characterization study is presented in this work, including the two main solicitation modes for this material: tensile and torsion. Different tests measure the shape recovery of Cu-Al-Ni single crystals wires during heating from room temperature to a temperature higher than temperature of end of martensitic transformation.

  6. Auto-combustion synthesis and characterization of Mg doped CuAlO2 nanoparticles

    Science.gov (United States)

    Agrawal, Shraddha; Parveen, Azra; Naqvi, A. H.

    2015-06-01

    The synthesis of pure and Mg doped Copper aluminumoxide CuAlO2nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO2 sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO2 has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

  7. Room Temperature Radiolytic Synthesized Cu@CuAlO2-Al2O3 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Alam Abedini

    2012-09-01

    Full Text Available Colloidal Cu@CuAlO2-Al2O3 bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a 60Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO2-Al2O3 nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM, energy dispersive X-ray spectrometry (EDX, and X-ray diffraction (XRD showed that Cu@CuAlO2-Al2O3 nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation.

  8. The response of macrophages to a Cu-Al-Ni shape memory alloy.

    Science.gov (United States)

    Colić, Miodrag; Tomić, Sergej; Rudolf, Rebeka; Anzel, Ivan; Lojen, Gorazd

    2010-09-01

    Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but little is known about their biocompatibility. The aim of this work was to study the response of rat peritoneal macrophages (PMØ) to a Cu-Al-Ni SMA in vitro, by measuring the functional activity of mitochondria, necrosis, apoptosis, and production of proinflammatory cytokines. Rapidly solidified (RS) thin ribbons were used for the tests. The control alloy was a permanent mold casting of the same composition, but without the shape memory effect. Our results showed that the control alloy was severely cytotoxic, whereas RS ribbons induced neither necrosis nor apoptosis of PMØ. These findings correlated with the data that RS ribbons are significantly more resistant to corrosion compared to the control alloy, as judged by the lesser release of Cu and Ni in the conditioning medium. However, the ribbons generated intracellular reactive oxygen species and upregulated the production of IL-6 by PMØ. These effects were almost completely abolished by conditioning the RS ribbons for 5 weeks. In conclusion, RS significantly improves the corrosion stability and biocompatibility of Cu-Al-Ni SMA. The biocompatibility of this functional material could be additionally enhanced by conditioning the ribbons in cell culture medium.

  9. Auto-combustion synthesis and characterization of Mg doped CuAlO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Shraddha, E-mail: shraddhaa32@gmail.com; Parveen, Azra; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg.& Technology, Aligarh Muslim University, Aligarh-202002 (India)

    2015-06-24

    The synthesis of pure and Mg doped Copper aluminumoxide CuAlO{sub 2}nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO{sub 2} sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO{sub 2} has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

  10. Magnetic properties dependence on the coupled effects of magnetic fields on the microstructure of as-deposited and post-annealed Co/Ni bilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Franczak, Agnieszka [LISM, Universite de Reims Champagne-Ardenne, BP 1039, 51687 Reims Cedex 2 (France); Department of Materials Science, Katholieke Universiteit Leuven, 3001 Leuven (Belgium); Levesque, Alexandra, E-mail: alexandra.levesque@univ-reims.fr [LISM, Universite de Reims Champagne-Ardenne, BP 1039, 51687 Reims Cedex 2 (France); Coïsson, Marco [Electromagnetism Division, Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy); Li, Donggang [LISM, Universite de Reims Champagne-Ardenne, BP 1039, 51687 Reims Cedex 2 (France); Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, 110004 Shenyang (China); Barrera, Gabriele [Electromagnetism Division, Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy); Università di Torino, Dipartimento di Chimica, 10125 Torino (Italy); Celegato, Federica [Electromagnetism Division, Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy); Wang, Qiang [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, 110004 Shenyang (China); Tiberto, Paola [Electromagnetism Division, Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy); Chopart, Jean-Paul [LISM, Universite de Reims Champagne-Ardenne, BP 1039, 51687 Reims Cedex 2 (France)

    2014-12-15

    Magnetic films and multilayers are the focus of much attention motivated mainly by their wide range of applications, such as magnetic data storage devices and sensors. The magnetic multilayer structures are normally prepared through physical means of deposition, as molecular beam epitaxy (MBE) or sputtering. However, there are already examples of materials produced by electrochemical routes, which share with the other deposition techniques a high sensitivity of magnetic and transport properties of the samples on their crystallographic and chemical structure. In addition, electrochemical deposition allows growing structures with high aspect ratio, which are not possible to obtain by MBE deposition followed by lithographic processes. The present work investigates the Co/Ni bilayered nanocrystalline films produced through the temperature-elevated electrochemical deposition, and modified by annealing carried out also under an external magnetic field. The results indicate an increase of the coercive field of deposited Co/Ni bilayers, when the electrodeposition process was conducted under magnetic field of 1 T. The annealing processing caused further remarkable increase of the coercive field of as-prepared bilayers that has been preserved under magnetic annealing conditions. The magnetic properties are discussed in terms of samples microstructure. In as-prepared samples the in-plane magnetization was observed, while high temperature treatment, causing microstructural changes in the film, resulted also in appearance of a small component of magnetization oriented perpendicularly to the films’ plane that could have been observed by MFM analysis. The induced perpendicular magnetization component in the post-annealed samples was a result of the magnetic field applied in the perpendicular direction to the samples’ surface during annealing treatment. - Highlights: • Co deposits were obtained at high electrolyte temperature under applied B-field. • The

  11. Rational design of a bi-layered reduced graphene oxide film on polystyrene foam for solar-driven interfacial water evaporation

    KAUST Repository

    Shi, Le

    2016-12-20

    Solar-driven water evaporation has been emerging as a highly efficient way for utilizing solar energy for clean water production and wastewater treatment. Here we rationally designed and fabricated a bi-layered photothermal membrane with a porous film of reduced graphene oxide (rGO) on the top and polystyrene (PS) foam at the bottom. The top porous rGO layer acts as a light absorber to harvest and convert light efficiently to thermal energy and the bottom PS layer, which purposefully disintegrates water transport channels, acts as an excellent thermal barrier to minimize heat transfer to the nonevaporative bulk water. The optimized bi-layered membrane was able to produce water evaporation rate as high as 1.31 kg m−2 h−1 with light to evaporation conversion efficiency as high as 83%, which makes it a promising photothermal material in the literature. Furthermore, the experiments and theoretical simulation were both conducted to examine the relationship between the overall energy efficiency and the depth of the photothermal material underwater and the experimental and simulations results coincided with each other. Therefore, this work provides systematic evidence in support of the concept of the interfacial heating and shines important light on practical applications of solar-driven processes for clean water production.

  12. Influence of loading and rotation speed on Friction and Wear properties of CuAlBi Alloy

    Institute of Scientific and Technical Information of China (English)

    Liu Rongchang; Dong Litao; Li Xingyuan; Chen Xiuhong

    2007-01-01

    The variation of the friction coefficient of the CuAlBi alloy at different connecting loading and friction speed were investigated by using MMU-5G sliding friction-wear tester, besides, the wear mass loss of the CuAlBi alloy was measured, and the influence of loading and rotation speed on friction and wear properties of CuAlBi alloy was also discussed. The results show that the friction coefficient increase then decrease with increase of connecting loading as well as decreases with increase of friction speed, and the wear loss mass increases with increase of connecting loading and friction speed. As a result, the wear failure form of CuAlBi alloy is mainly ploughing.

  13. Assembly of crosslinked oxo-cyanoruthenate and zirconium oxide bilayers: Application in electrocatalytic films based on organically modified silica with templated pores

    Science.gov (United States)

    Rutkowska, Iwona A.; Sek, Jakub P.; Mehdi, B. Layla; Kulesza, Pawel J.; Cox, James A.

    2014-01-01

    Electrochemical deposition of crosslinked oxo-cyanoruthenate, Ru-O/CN-O, from a mixture of RuCl3 and K4Ru(CN)6 is known to yield a film on glassy carbon that promotes oxidations by a combination of electron and oxygen transfer. Layer-by-layer (LbL) deposition of this species and of a film formed by cycling of the electrode potential in a ZrO2 solution systematically increases the number of catalytically active sites of the Ru-O/CN-O on the electrode. The evaluation of the electrocatalytic activity was by cyclic voltammetric oxidation of cysteine at pH 2. Plots of the anodic peak current vs. the square root of scan rate were indicative of linear diffusion control of this oxidation, even in the absence of ZrO2, but the slopes of these linear plots increased with bilayer number, n, of (ZrO2 | Ru-O/CN-O)n. The latter observation is hypothesized to be due to an increased number of active sites for a given geometric electrode area, but proof required further study. To optimize utilization of the catalyst and to provide a size-exclusion characteristic to the electrode, the study was extended to LbL deposition of the composite in 50-nm pores of an organically modified silica film deposited by electrochemically assisted sol-gel processing using surface-bound poly(styrene sulfonate) nanospheres as a templating agent. PMID:24683266

  14. Assembly of crosslinked oxo-cyanoruthenate and zirconium oxide bilayers: Application in electrocatalytic films based on organically modified silica with templated pores.

    Science.gov (United States)

    Rutkowska, Iwona A; Sek, Jakub P; Mehdi, B Layla; Kulesza, Pawel J; Cox, James A

    2014-03-10

    Electrochemical deposition of crosslinked oxo-cyanoruthenate, Ru-O/CN-O, from a mixture of RuCl3 and K4Ru(CN)6 is known to yield a film on glassy carbon that promotes oxidations by a combination of electron and oxygen transfer. Layer-by-layer (LbL) deposition of this species and of a film formed by cycling of the electrode potential in a ZrO2 solution systematically increases the number of catalytically active sites of the Ru-O/CN-O on the electrode. The evaluation of the electrocatalytic activity was by cyclic voltammetric oxidation of cysteine at pH 2. Plots of the anodic peak current vs. the square root of scan rate were indicative of linear diffusion control of this oxidation, even in the absence of ZrO2, but the slopes of these linear plots increased with bilayer number, n, of (ZrO2 | Ru-O/CN-O) n . The latter observation is hypothesized to be due to an increased number of active sites for a given geometric electrode area, but proof required further study. To optimize utilization of the catalyst and to provide a size-exclusion characteristic to the electrode, the study was extended to LbL deposition of the composite in 50-nm pores of an organically modified silica film deposited by electrochemically assisted sol-gel processing using surface-bound poly(styrene sulfonate) nanospheres as a templating agent.

  15. Enhanced conversion efficiency in dye-sensitized solar cells based on bilayered nano-composite photoanode film consisting of TiO2 nanoparticles and nanofibers.

    Science.gov (United States)

    Du, P F; Song, L X; Xiong, J

    2014-06-01

    Novel TiO2 nanoparticles/nanofibers (NPs/NFs) bilayered nano-composite photoanode film for dye-sensitized solar cells (DSSCs) was fabricated through the combination of spin-coating and electrospinning. The NPs and NFs layers have complementary roles. The underlaid spin-coated NPs layer provides the photoanode film with higher specific surface area for dye adsorption and improved adhesion to conductive glass substrate. The overlaid electrospun NFs layer endows the photoanode film with better dye-loading and light-harvesting capabilities due to its porous meshwork structure. And the NFs layer also offers larger pore volume, which can facilitate the electrolyte diffusion and the activity regeneration of dye sensitizers. As a result, the electron transport is accelerated while the charge recombination is suppressed. Ascribing to the synergic effect of the NPs and NFs layers, the TiO2 NPs/NFs-based DSSCs achieve a conversion efficiency of 4.46%, which is nearly 14% higher than that of the pure TiO2 NPs-based ones.

  16. Influence of different substrates on the ionic conduction in LiCoO{sub 2}/LiNbO{sub 3} thin-film bi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Horopanitis, E.E.; Perentzis, G.; Papadimitriou, L. [Aristotle University of Thessaloniki, Department of Physics, Section of Solid State Physics, Thessaloniki (Greece)

    2008-07-01

    LiNbO{sub 3} thin films, deposited by e-gun evaporation, show lithium deficiency, which is cured by ''Li doping''. The ''Li doping'' of the films was achieved by preparing a structure of Li-Nb-O/Li/Li-Nb-O, which after annealing forms a homogenized LiNbO{sub 3} layer because of diffusion of Li in the two Li-Nb-O layers. The LiCoO{sub 2}/LiNbO{sub 3} bi-layers were prepared either on Stainless Steel/TiN or on Al{sub 2}O{sub 3}/Co/Pt substrates/ohmic-contacts by depositing first either the cathode LiCoO{sub 2} or the electrolyte LiNbO{sub 3}. The Nyquist plots of the AC impedance measurements of all structures showed that the interfaces prepared on Stainless-Steel/TiN consisted of two semicircles. The structures deposited on Al{sub 2}O{sub 3}/Co/Pt showed a third semicircle, which is probably due to the roughness of the substrate. It is important that the ionic properties of the bi-layers with the cathode material deposited first, a usual structure in a microbattery, are improved compared to the other structures. The quality of the LiNbO{sub 3} layer depends very much on the substrate. It can be evaluated from Arrhenius plots that the activation energy of this layer is considerably lower when the whole structure is deposited on Stainless Steel/TiN. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Magnetoelectric Bi3.15Nd0.85Ti3O12–NiFe2O4 bilayer films derived by a SOL–GEL method

    Directory of Open Access Journals (Sweden)

    Feng Yang

    2015-08-01

    Full Text Available Magnetoelectric Bi3.15Nd0.85Ti3O12–NiFe2O4 (BNT–NFO bilayer films were deposited on Pt/Ti/SiO2/Si(100 substrates by a simple SOL–GEL method and spin-coating process with different growth sequences of BNT and NFO yielding the following layered structures: BNT/NFO/substrate (BNS and NFO/BNT/substrate (NBS. Such heterostructures present simultaneously strong ferroelectric and ferromagnetic responses, as well as magnetoelectric effects at room temperature. BNS thin films showed larger ME voltage coefficient than NBS films, revealing that the layer sequences have a significant influence on the magnetoelectric coupling behavior of these bilayer structures, which may be caused by a interfacial effect.

  18. Non-Arrhenius growth behavior, bilayer and reentrant layer growth for ultrathin Co films on Cu(0 0 1)

    CERN Document Server

    Bernhard, T; Winter, H

    2003-01-01

    Grazing scattering of 25 keV He atoms is applied to study island nucleation and growth of Co on Cu(0 0 1) in real time and real space. With decreasing growth temperature, we observe, starting at 470 K, step-flow growth, layer growth, bilayer growth and, below 210 K, reentrant layer growth. The density of nucleated islands shows a complex 'N-shaped' dependence on temperature, which is at variance with standard nucleation theory. Results are explained on the basis of recent density-functional calculations.

  19. An analysis of non-classical austenite-martensite interfaces in CuAlNi

    CERN Document Server

    Ball, J M; Seiner, H

    2011-01-01

    Ball and Carstensen theoretically investigated the possibility of the occurrence of non-classical austenite-martensite interfaces and studied the cubic-to-tetragonal case extensively. Here, we aim to present an analysis of such interfaces recently observed by Seiner et al. in CuAlNi single crystals, undergoing a cubic-to-orthorhombic transition. We show that they can be described by the non-linear elasticity model for martensitic transformations and we make some predictions regarding the volume fractions of the martensitic variants involved, as well as the habit plane normals.

  20. Laser stimulated kinetics effects on the phase transition of the ferromagnetic/superconducting MgB{sub 2}/(CrO{sub 2}) bilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    AlZayed, N.S. [Physics and Astronomy Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Kityk, I.V., E-mail: ikityk@el.pcz.czest.pl [Faculty of Electrical Engineering, Czestochowa University Technology, Armii Krajowej 17, PL-42201 Czestochowa (Poland); Soltan, S. [Max Planck Institute, Solid State Research, D-70569 Stuttgart (Germany); Physics Department, Faculty of Science, Helwan University, 11798 Helwan, Cairo (Egypt); Wojciechowski, A. [Faculty of Electrical Engineering, Czestochowa University Technology, Armii Krajowej 17, PL-42201 Czestochowa (Poland); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, Pekarska St., 50, 79010 Lviv (Ukraine); Lakshminarayana, G. [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Shahabuddin, M. [Physics and Astronomy Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2014-05-01

    Graphical abstract: Dependence of resistance versus temperature for different power densities. The nonzero value is generated from the bottom CrO{sub 2} resistive layer. The onset transition temperature is our reference for the enhancement value. - Highlights: • Photoinduced enhancement of critical temperature in MgB{sub 2}–Cr{sub 2}O{sub 3} films was found. • Crucail role of electron–phonon interacton was shown. • Optimal ratio fundamental/SHG intensities was varied within 4:1 and 6:1. - Abstract: Using bicolor laser treatment by Nd:YAG 20 ns laser (1064–532 nm) and 180 ns CO{sub 2} laser beams (10.6–5.3 μm) it was shown a possibility of critical temperature enhancement in ferromagnetic superconducting MgB{sub 2}/CrO{sub 2} bilayer films. The role of the phonon sub-system effectively interacting with 3d Cr originating localized trapping levels is discussed. The pump–probe laser kinetics for the probing second harmonic generation at 1064 nm is explored in details to show principal role of the localized trapping levels. The relaxation of the processes after the switching off the photo inducing beams show the disappearance of the enhanced superconductivity after the 20–30 s. The temperature dependence of the resistance show nonlinear dependence versus the pumping power and different optimal fundamental to writing power density beams ratio.

  1. Effect of tellurium on machinability and mechanical property of CuAlMnZn shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu Na [School of Materials Science and Engineering, Central South University, Changsha, 410083 (China); Li Zhou, E-mail: lizhou6931@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha, 410083 (China); Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Changsha, 410083 (China); Xu Genying; Feng Ze; Gong Shu; Zhu Lilong; Liang Shuquan [School of Materials Science and Engineering, Central South University, Changsha, 410083 (China)

    2011-10-15

    Highlights: {yields} A novel free-machining Cu-7.5Al-9.7Mn-3.4Zn-0.3Te (wt.%) shape memory alloy has been developed. {yields} The size of dispersed particles with richer Te is 2-5 {mu}m. {yields} The CuAlMnZnTe alloy has good machinability which approached that of BZn15-24-1.5 due to the addition of Te. {yields} Its shape memory property keeps the same as that of CuAlMnZn alloy with free Te. {yields} The CuAlMnZn shape memory alloy with and without Te both have good ductile as annealed at 700 deg. C for 15 min. - Abstract: The microstructure transition, shape memory effect, machinability and mechanical property of the CuAlMnZn alloy with and without Te have been studied using X-ray diffraction analysis, chips observation and scanning electron microscopy (SEM), tensile strength test and differential scanning calorimeter (DSC), and semi-quantitative shape memory effect (SME) test. The particles with richer Te dispersedly distributed in grain interior and boundary with size of 2-5 {mu}m. After the addition of Te, the CuAlMnZnTe alloy machinability has been effectively increased to approach that of BZn15-24-1.5 and its shape memory property remains the same as the one of CuAlMnZn alloy. The CuAlMnZn shape memory alloys with and without Te both have good ductility as annealed at 700 deg. C for 15 min.

  2. Preparation of Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate by coprecipitation and its uptake of rare earth ions from aqueous solution

    Science.gov (United States)

    Kameda, Tomohito; Hoshi, Kazuaki; Yoshioka, Toshiaki

    2013-03-01

    A Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate (edta•Cu-Al LDH) was prepared by the dropwise addition of a Cu-Al nitrate solution to an edta solution at constant pH values of 8.0, 9.0, and 10.0. The edta•Cu-Al LDH had Hedta3- in the interlayer. Furthermore, the preparation at pH 8.0 resulted in the intercalation of Cu(edta)2-. The edta•Cu-Al LDH was found to take up rare earth ions from aqueous solution. The uptake of Sc3+ and Y3+ by edta•Cu-Al LDH was attributed to both the chelating functions of the edta ion in the interlayer and the chemical properties of Cu-Al LDH itself. The uptake of La3+ by edta•Cu-Al LDH was primarily caused by the chelating function of edta ions in the interlayer. The edta ions in the edta•Cu-Al LDH interlayer formed chelate complexes in the order Sc3+ > Y3+ > La3+ due to their relative stabilities, Sc(edta)- > Y(edta)- > La(edta)-. Thus, edta ions retain their chelating function even when intercalated in a Cu-Al LDH interlayer.

  3. Application of Cu-Al-Mn superelastic alloy bars as reinforcement elements in concrete beams

    Science.gov (United States)

    Shrestha, Kshitij C.; Araki, Yoshikazu; Nagae, Takuya; Yano, Hayato; Koetaka, Yuji; Omori, Toshihiro; Sutou, Yuji; Kainuma, Ryosuke; Ishida, Kiyohito

    2012-04-01

    Experimental works are done to assess the seismic behavior of concrete beams reinforced with superelastic alloy (SEA) bars. Applicability of newly developed Cu-Al-Mn SEA bars, characterized by large recovery strain, low material cost, and high machinability, have been proposed as partial replacements for conventional steel bars in order to reduce residual deformations in structures during and after intense earthquakes. Four-point reverse-cyclic bending tests were done on 1/3 scale concrete beams comprising three different types of specimens - conventional steel reinforced concrete (ST-RC), SEA reinforced concrete (SEA-RC), and SEA reinforced concrete with pre-tensioning (SEA-PC). The results showed that SEA reinforced concrete beams demonstrated significant enhancement in crack recovery capacity in comparison to steel reinforced beam. Average recovery of cracks for each of the specimens was 21% for ST-RC, 84% for SEA-RC, and 86% for SEA-PC. In addition, SEA-RC and SEA-PC beams demonstrated strong capability of recentering with comparable normalized strength and ductility relative to conventional ST-RC beam specimen. ST-RC beam, on the other hand, showed large residual cracks due to progressive reduction in its re-centering capability with each cycle. Both the SEA-RC and SEA-PC specimens demonstrated superiority of Cu-Al-Mn SEA bars to conventional steel reinforcing bars as reinforcement elements.

  4. Visible light induced H2PO(4)(-) removal over CuAlO2 catalyst.

    Science.gov (United States)

    Benreguia, N; Omeiri, S; Bellal, B; Trari, M

    2011-09-15

    The delafossite CuAlO(2) is successfully used for the visible light driven H(2)PO(4)(-) reduction. It is prepared from the nitrates decomposition in order to increase the ratio of reaction surface per given mass. CuAlO(2) is a narrow band gap semiconductor which exhibits a good chemical stability with a corrosion rate of 1.70 μmol year(-1) at neutral pH. The flat band potential (+0.25 V(SCE)) is determined from the Mott-Schottky characteristic. Hence, the conduction band, positioned at (-1.19 V(SCE)), lies below the H(2)PO(4)(-) level yielding a spontaneous reduction under visible illumination. The photocatalytic process is investigated under mild conditions and 30% conversion occurs in less than ~6h with a quantum efficiency of 0.04% under full light. The concentration decreases by a factor of 39% after a second cycle. The photoactivity follows a first order kinetic with a rate constant of 6.6 × 10(-2)h(-1). The possibility of identifying the reaction products via the intensity-potential characteristics is explored. The decrease of the conversion rate over illumination time is due to the competitive water reduction.

  5. Diffusive phenomena and pseudoelasticity in Cu-Al-Be single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sade, M., E-mail: sade@cab.cnea.gov.ar [Centro Atómico Bariloche (CNEA), Av. E. Bustillo km. 9500, 8400 S.C. de Bariloche (Argentina); CONICET (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo, Av. E. Bustillo km. 9500, 8400 S.C. de Bariloche (Argentina); Pelegrina, J.L., E-mail: jlp201@cab.cnea.gov.ar [Centro Atómico Bariloche (CNEA), Av. E. Bustillo km. 9500, 8400 S.C. de Bariloche (Argentina); CONICET (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo, Av. E. Bustillo km. 9500, 8400 S.C. de Bariloche (Argentina); Yawny, A., E-mail: yawny@cab.cnea.gov.ar [Centro Atómico Bariloche (CNEA), Av. E. Bustillo km. 9500, 8400 S.C. de Bariloche (Argentina); CONICET (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo, Av. E. Bustillo km. 9500, 8400 S.C. de Bariloche (Argentina); Lovey, F.C., E-mail: lovey@cab.cnea.gov.ar [Centro Atómico Bariloche (CNEA), Av. E. Bustillo km. 9500, 8400 S.C. de Bariloche (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo, Av. E. Bustillo km. 9500, 8400 S.C. de Bariloche (Argentina)

    2015-02-15

    Highlights: • Diffusive phenomena occurring under load were analyzed in Cu-Al-Be single crystals. • Stabilization of stress induced martensite was detected in a range of temperatures. • Ageing the austenite under load shifts the austenite/martensite stability field. • A free energy model is proposed considering interchanges between Cu and Be atoms. • Different kinetics for the recovery of the austenite are rationalized. - Abstract: Cu-Al-Be single crystals show pseudoelasticity and the shape memory effect in a well-defined composition range. The β{sub 3}-18R martensitic transition is the origin of these phenomena. The transformation temperatures and the critical stresses to induce the martensitic transition are affected by diffusive phenomena taking place both in the parent phase and in martensite. Pseudoelastic cycles were used to obtain quantitative data concerning the effect of diffusive phenomena like stabilization of martensite, ordering of the parent phase under load and recovery of this phase on the critical stresses to transform. Information was then obtained on changes in the relative phase stability. A model is presented to explain those changes taking place in the parent phase aged under load and in the martensitic 18R structure. Experimental data on the kinetics of diffusive phenomena is also presented and analyzed.

  6. Strength and thermal stability of Cu-Al2O3 composite obtained by internal oxidation

    Directory of Open Access Journals (Sweden)

    Jovanovic, M. T.

    2010-12-01

    Full Text Available The objective of the work is to study the effects of the high-energy milling on strengthening, thermal stability and electrical conductivity of Cu-Al2O3 composite. The prealloyed copper powders, atomized in inert gas and containing 3 wt. % Al, were milled up to 20 h in the planetary ball mill to oxidize in situ aluminium with oxygen from the air. Composite compacts were obtained by hot-pressing in an argon atmosphere at 800 °C for 3 h under the pressure of 35MPa. The microstructural characterization was performed by the optical microscope, scanning electron microscope (SEM, transmission electron microscope (TEM and X-ray diffraction analysis (XRD. The microhardness, electrical conductivity and density measurements were also carried out. The effect of internal oxidation and high-energy milling on strengthening of Cu-Al2O3 composite was significant, The increase of the microhardness of composite compacts (292 HV is almost threefold comparing to compacts processed from the as-received Cu-3 wt. % Al powder (102 HV. The grain size of Cu-Al2O3 compacts processed from 5 and 20 h-milled powders was 75 and 45 nm, respectively. The small increase in the grain size and the small microhardness drop indicate the high thermal stability of Cu-Al2O3 composite during high-temperature exposure at 800 °C.El objetivo del trabajo es el estudio de los efectos de la pulverización con altas energías sobre la resistencia, estabilidad térmica y conductividad eléctrica del compuesto Cu-Al2O3. El polvo pre-aleado de cobre, obtenido a través de la atomización con gas inerte y con un contenido de 3wt. % Al, se molió durante 20 h en el molino planetario de bolas dando lugar a la oxidación in situ del aluminio con el oxígeno del aire. El compuesto compactado se ha obtenido mediante prensado en caliente en atmósfera de argón a 800 °C durante 3 h y a una presión de 35MPa. La caracterización microestructural se hizo a través de microscopia óptica, microscopia

  7. From Fe3O4 /NiO bilayers to NiFe2O4 -like thin films through Ni interdiffusion

    Science.gov (United States)

    Kuschel, O.; Buß, R.; Spiess, W.; Schemme, T.; Wöllermann, J.; Balinski, K.; N'Diaye, A. T.; Kuschel, T.; Wollschläger, J.; Kuepper, K.

    2016-09-01

    Ferrites with (inverse) spinel structure display a large variety of electronic and magnetic properties, making some of them interesting for potential applications in spintronics. We investigate the thermally induced interdiffusion of Ni2 + ions out of NiO into Fe3O4 ultrathin films, resulting in off-stoichiometric nickel ferrite-like thin layers. We synthesized epitaxial Fe3O4 /NiO bilayers on Nb-doped SrTiO3(001) substrates by means of reactive molecular beam epitaxy. Subsequently, we performed an annealing cycle comprising three steps at temperatures of 400 ∘C , 600 ∘C , and 800 ∘C under an oxygen background atmosphere. We studied the changes of the chemical and electronic properties as result of each annealing step with help of hard x-ray photoelectron spectroscopy and found a rather homogeneous distribution of Ni and Fe cations throughout the entire film after the overall annealing cycle. For one sample we observed a cationic distribution close to that of the spinel ferrite NiFe2O4 . Further evidence comes from low-energy electron diffraction patterns indicating a spinel-type structure at the surface after annealing. Site- and element-specific hysteresis loops performed by x-ray magnetic circular dichroism uncovered the antiferrimagnetic alignment between the octahedral coordinated Ni2 + and Fe3 + ions and the Fe3 + ion in tetrahedral coordination. We find a quite low coercive field of 0.02 T, indicating a rather low defect concentration within the thin ferrite films.

  8. Synthesis of the p-type semiconducting ternary oxide CuAlO{sub 2} using the Pechini method

    Energy Technology Data Exchange (ETDEWEB)

    Jarman, Richard H., E-mail: Jarman@cod.edu [College of DuPage, 425 Fawell Boulevard, Glen Ellyn, IL 60137-6599 (United States); Bafia, Julie; Gebreslasse, Tsige [College of DuPage, 425 Fawell Boulevard, Glen Ellyn, IL 60137-6599 (United States); Ingram, Brian J.; Carter, J. David [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2013-10-15

    Graphical abstract: - Highlights: • We have prepared single-phase samples of the semiconducting oxide CuAlO{sub 2} using the Pechini method. • Reaction times are reduced relative to conventional solid-state synthesis. • Products have high surface area suitable for ceramic processing. • Product composition is dictated by thermodynamic control; CuAl{sub 2}O{sub 4} is obtained preferentially at lower temperature. - Abstract: The synthesis of the delafossite phase CuAlO{sub 2} using the Pechini method was investigated. Powder X-ray diffraction data showed that pure, single-phase samples were obtained after only 3 h heating at 1100 °C. CuAl{sub 2}O{sub 4}, which contains Cu(II) rather than Cu(I), was the dominant phase between 700 and 1100 °C. Conversion to CuAlO{sub 2} is promoted by the positive entropy change associated with the evolution of oxygen. No mixed Cu–Al oxide was formed below 700 °C.

  9. A radioluminescent nuclear battery using volumetric configuration: (63)Ni solution/ZnS:Cu,Al/InGaP.

    Science.gov (United States)

    Russo, Johnny; Litz, Marc; Ray, William; Smith, Brenda; Moyers, Richard

    2017-09-14

    Energy dense power sources are critical to the development of compact, remote sensors for terrestrial and space applications. Nuclear batteries using β(-)-emitting radioisotopes possess energy densities 1000 times greater than chemical batteries. Their power generation is a function of β(-) flux saturation point relative to the planar (2D) configuration, β(-) range, and semiconductor converter. An approach to increase power density in a beta-photovoltaic (β-PV) nuclear battery is described. By using volumetric (3D) configuration, the radioisotope, nickel-63 ((63)Ni) in a chloride solution was integrated in a phosphor film (ZnS:Cu,Al) where the β(-) energy is converted into optical energy. The optical energy was converted to electrical energy via an indium gallium phosphate (InGaP) photovoltaic (PV) cell, which was optimized for low light illumination and closely matched to radioluminescence (RL) spectrum. With 15mCi of (63)Ni activity, the 3D configuration energy values surpassed 2D configuration results. The highest total power conversion efficiency (ηt) of 3D configuration was 0.289% at 200µm compared 0.0638% for 2D configuration at 50µm. The highest electrical power and ηt for the 3D configuration were 3.35 nWe/cm(2) at an activity of 30mCi and 0.289% at an activity of 15mCi, respectively. By using 3D configuration, the interaction space between the radioisotope source and scintillation material increased, allowing for significant electrical energy output, relative to the 2D configuration. These initial results represent a first step to increase nuclear battery power density from microwatts to milliwatts per 1000cm(3) with the implementation of higher energy β(-) sources. Published by Elsevier Ltd.

  10. Effect of the diameter on Cu-Al post retention Efeito do diâmetro na retenção de pinos de Cu-Al

    Directory of Open Access Journals (Sweden)

    Celso Bernardo de Souza Filho

    2004-09-01

    Full Text Available This study compared the resistance to removal by traction of abraded cylindrical metal cast posts of Cu-Al (Goldent-LA. The posts had constant length (9 mm and three different diameters (0.9, 1.3 and 1.7 mm, and were cemented with zinc phosphate cement. The crowns of 36 sound maxillary canines were sectioned, the roots were immersed in resin blocks and the root canals were endodontically treated. The teeth were divided into three groups to be prepared and standardized with the use of a parallelometer with the following burs: Group 1 - Largo n. 2; Group 2 - Largo n. 4; Group 3 - Largo n. 6. The posts were molded with chemically activated resin and after casting they were abraded and their dimensions were confirmed with a digital caliper. After cementation of the posts in the prepared root canals, the samples were kept at 37ºC in distilled water for 7 days and subsequently submitted to the traction test in a universal testing machine (Instron 4444. The results showed no statistical difference between the groups. Diameter variation (0.9 mm, 1.3 mm and 1.7 mm in abraded cylindrical posts cemented with zinc phosphate did not affect resistance to removal.Este estudo in vitro comparou a resistência à remoção por tração de núcleos metálicos fundidos em liga de Cu-Al (Goldent-LA cilíndricos, jateados, de comprimento constante igual a 9 mm, cimentados com cimento de fosfato de zinco e com três diferentes diâmetros: 0,9 mm, 1,3 mm e 1,7 mm. Trinta e seis caninos superiores hígidos tiveram suas coroas seccionadas, sendo as raízes incluídas em blocos de resina acrílica, e os canais, tratados endodonticamente. Os dentes foram divididos em três grupos para serem preparados e padronizados com o auxílio de um paralelômetro com as seguintes brocas: Grupo 1 - Largo nº 2; Grupo 2 - Largo nº 4; Grupo 3 - Largo nº 6. Os núcleos foram moldados com resina acrílica ativada quimicamente e, após a fundição, foram jateados e tiveram as suas

  11. Effect of Co element on microstructure and mechanical properties of FeCoxNiCuAl alloys

    Institute of Scientific and Technical Information of China (English)

    Yanxin ZHUANG; Wenjie LIU; Pengfei XING; Fei WANG; Jicheng HE

    2012-01-01

    FeCoxNiCuAl (x values in molar ratio,x=0.2,0.5,1,1.5,2 and 3) alloys were prepared using a suck-casting method.The effect of Co element on phase constituents,microstructure and mechanical properties of the FeCoxNiCuAl alloys was investigated using X-ray diffraction,scanning electron microscopy,optical microscopy and compressive tests.It was found that the Co addition has a significant influence on the structure and properties of the FeCoxNiCuAl alloys.The alloys have typical dendrite microstructure,and are composed of a simple fcc structure and bcc structure.The addition of Co promotes the formation of fcc phase in the alloys,retards the compressive strength and hardness of the alloys,and enhances the plasticity of the alloys.

  12. Effects of Composition and Thermal Cycle on Transformation Behaviors, Thermal Stability and Mechanical Properties of CuAlAg Alloy

    Institute of Scientific and Technical Information of China (English)

    Yunqing MA; Chengbao JIANG; Lifen DENG; Huibin XU

    2003-01-01

    The phase transformation behavior, mechanical properties, and the thermal stability of CuAlAg alloy were studied andminor rare earth (0.1 wt pct La+Ce) was added to improve the mechanical property of the studied alloy. It was foundthat Ag addition in the CuAl binary alloy can improve the stability of martensitic transformation and high Al contentleads to the disappearing of martensitic transformation. The tensile strength and strain of the Cu-10.6Al-5.8Ag (wtpct) alloy were measured to be 383.5 MPa and 0.86%, respectively. With rare earth addition, the tensile strainincreased from 0.86% to 1.47%. The CuAlAg alloy did not exhibit martensitic transformation on the second heatingprocess. Its poor thermal stability still needs to be improved.

  13. THERMAL CYCLING UNDER LOADING OF SINGLE CRYSTAL Cu-Al-Ni AFTER AGING

    Directory of Open Access Journals (Sweden)

    Ignacio Corro

    2016-06-01

    Full Text Available In this paper, a study of single crystal Cu-14.3Al-4.1Ni (%wt subjected to thermal cycling under loading is presented. Shape memory Cu-Al-Ni has low diffusion at temperatures above room temperature. Therefore, it is interesting to know your answer in working conditions and after being aged in this temperature range. Specimens were characterized before and after aging, using a device designed by the authors. Parameters such as critical temperatures and hysteresis width, the repeatability of the curves and the type of TM induced were analyzed. These parameters have changes then the aging or contribute to that may influence the design of applications.

  14. Room temperature fatigue behavior of OFHC copper and CuAl25 specimens of two sizes

    DEFF Research Database (Denmark)

    Singhal, A.; Stubbins, J.F.; Singh, B.N.

    1994-01-01

    requiring an understanding of their fatigue behavior.This paper describes the room temperature fatigue behavior of unirradiated OFHC (oxygen-free high-conductivity) copper and CuAl25 (copper strengthened with a 0.25% atom fraction dispersion of alumina). The response of two fatigue specimen sizes to strain......Copper and its alloys are appealing for application in fusion reactor systems for high heat flux components where high thermal conductivities are critical, for instance, in divertor components. The thermal and mechanical loading of such components will be, at least in part, cyclic in nature, thus...... controlled fatigue loading is examined, and differences in behavior are discussed. Specimens with the smaller size are now being irradiated in several reactors...

  15. Effect of coating thickness on microstructures and mechanical properties of C/Cu/Al composites

    Institute of Scientific and Technical Information of China (English)

    CAO Zhuo-kun; YAO Guang-chun; LIU Yi-han

    2006-01-01

    The different copper coatings with thickness varying from 0.3 μm to 1.5 μtm were deposited on carbon fibers using either electroless plating or electroplating method. The coated fibers were chopped and composites were fabricated with melting aluminum at 700 ℃. The effect of the copper layer on the microstructure in the system was discussed. The results show that the copper layer has fully reacted with aluminum matrix, and the intermetallic compound CuAl2 forms through SEM observation and XRD, EDX analysis. The results of tensile tests indicate that composites fabricated using carbon fibers with 0.7-1.1 μm copper coating perform best and the composites turn to more brittle as the thickness of copper coating increases. The fracture surface observation exhibits good interface bonding and ductility of the matrix alloy when the thickness of copper coating is about 0.7-1.1 μm.

  16. Thermodynamic and Optical Properties of CuAlO2 under Pressure from First Principle

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liqin; CHENG Yan; JI Guangfu

    2015-01-01

    The structural stability, thermodynamic and optical properties of delafossite CuAlO2 were investigated using the norm-conserving pseudopotential technique based on the ifrst-principle density-functional theory. The ground-state properties obtained by minimizing the total energy were in favorable agreement with previous works. By using the quasi-harmonic Debye model, the thermodynamic properties including the Debye temperature QD, heat capacity CV, thermal expansion coefifcient a, and Grüneisen parameter g were successfully obtained in the temperature range from 0 to 1 000 K and pressure range from 0 to 80 GPa, respectively. The optical properties including dielectric function e(v), absorption coefifcient a(v), relfectivity coefifcient R(v), and refractive index n(v) were also calculated and analyzed.

  17. Thermal Spraying of CuAlFe Powder on Cu5Sn Alloy

    Science.gov (United States)

    Roata, I. C.; Pascu, A.; Croitoru, C.; Stanciu, E. M.; Pop, M. A.

    2017-06-01

    To improve the corrosion and wear resistance of copper and its alloys, flame spraying has been employed to obtain a relatively homogenous Cu/Al/Fe-based coating. To minimize the defects that usually occur by using this method, a post-coating annealing step has been employed, by using concentrated solar energy as means of thermal surface treatment. Scanning electron micrographs have indicated a reduction in the cracks/pores density and accelerated corrosion testing have indicated a higher performance of the solar-annealed sample, in comparison with the initial reference material. The coating approach mentioned in this paper could be successfully applied to restore several worn tools and instruments, and could also be of use in the renewable energy field (IR-absorbent coatings) or in advanced oxidation processes, such as photocatalysis.

  18. Microstructural and chemical transformation of thin Ti/Pd and TiDy/Pd bilayer films induced by vacuum annealing

    NARCIS (Netherlands)

    Lisowski, W.; Keim, E.G.; Kaszkur, Z.; Berg, van den A.H.J.; Smithers, M.A.

    2007-01-01

    Using a combination of scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction and X-ray photoelectron spectroscopy (XPS), we made a comparative study of the high-temperature annealing impact on thin titanium deuteride (TiD y ) films covered by an ultrathin Pd layer,

  19. Nanomechanical properties and thermal decomposition of Cu-Al2O3 composites for FGM applications

    Directory of Open Access Journals (Sweden)

    Koumoulos Elias P.

    2016-01-01

    Full Text Available It is widely reported that copper-alumina (Cu-Al2O3 nanocomposite materials exhibit high potential for use in structural applications in which enhanced mechanical characteristics are required. The investigation of Cu-Al2O3 nanocomposites which are to form a functionally graded material (FGM structure in terms of nanomechanical/structural integrity and thermal stability is still scarce. In this work, fully characterized nanosized Al2O3 powder has been incorporated in Cu matrix in various compositions (2, 5 and 10 wt.% of Al2O3 content. The produced composites were evaluated in terms of their morphology, structural analysis, thermal behavior, nanomechanical properties and their extent of viscoplasticity. The results reveal that all nanocomposites degrade at elevated temperatures; increased surface mass gain with decreasing Al2O3 content was observed, while no such difference of % mass gain in 5 and 10 wt.% of Al and Al2O3 content in Cu was observed. The increase of Al2O3 wt.% content results in thermal stability enhancement of the nanocomposites. The thermal decomposition process of the material is reduced in the presence of 10 wt.% of Al2O3 content. This result for the matrix decomposition can be explained by a decrease in the diffusion of oxygen and volatile degradation products throughout the composite material due to the incorporation of Al and Al2O3. The Al2O3 powder enhances the overall thermal stability of the system. All samples exhibited significant pile-up of the materials after nanoindentation testing. Increasing the wt.% of Al2O3 content was found to increase the creep deformation of the samples as well as the hardness and elastic modulus values.

  20. Bi{sub 1.5}Mg{sub 1.0}Nb{sub 1.5}O{sub 7}/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} bilayer thin films prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shihui [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China); Li, Lingxia, E-mail: lingxiali@126.com [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China); Zhang, Ning; Dong, Helei; Xu, Dan [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China); Zhang, Weifeng [Key Laboratory of Photovoltaic Materials of Henan Province and School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

    2014-11-05

    Highlights: • Bi{sub 1.5}Mg{sub 1.0}Nb{sub 1.5}O{sub 7}/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} films were prepared by pulsed laser deposition. • The bilayered films have a high figure of merit of 61.5. • Thickness ratio dependence of permittivity and tangent loss was discussed. • The mechanism of the leakage current of the bilayered films was explained possibly. - Abstract: Bi{sub 1.5}Mg{sub 1.0}Nb{sub 1.5}O{sub 7}/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BMN/BST) bilayer thin films have been prepared on Au/TiO{sub x}/SiO{sub 2}/Si substrates by pulsed laser deposition. The structure and electrical properties of BMN/BST bilayer thin films were investigated. X-ray diffraction results showed that the structure of BMN/BST bilayer thin films was composed of a cubic BMN pyrochlore phase and a cubic BST perovskite phase. The dielectric measurements showed that the BMN layer had played a positive role in improving the electrical properties of the thin films. With the increased thickness of BMN, the dielectric loss was significantly lowered, accompanied with a tolerable reduction of tunability. The BMN/BST bilayer thin films at a BMN/BST thickness ratio of 1 give the highest figure of merit of 61.5 and the largest commutation quality factor of 5163. In addition, the thickness effect was discussed with a series connection model of bilayered capacitors, and the calculated dielectric constant and loss tangent were obtained.

  1. Polydopamine-Supported Lipid Bilayers

    Directory of Open Access Journals (Sweden)

    Souryvanh Nirasay

    2012-12-01

    Full Text Available We report the formation of lipid membranes supported by a soft polymeric cushion of polydopamine. First, 20 nm thick polydopamine films were formed on mica substrates. Atomic force microscopy imaging indicated that these films were also soft with a surface roughness of 2 nm under hydrated conditions. A zwitterionic phospholipid bilayer was then deposited on the polydopamine cushion by fusion of dimyristoylphosphatidylcholine (DMPC and dioleoylphosphatidylcholine (DOPC vesicles. Polydopamine films preserved the lateral mobility of the phospholipids as shown by fluorescence microscopy recovery after photobleaching (FRAP experiments. Diffusion coefficients of ~5.9 and 7.2 µm2 s−1 were respectively determined for DMPC and DOPC at room temperature, values which are characteristic of lipids in a free standing bilayer system.

  2. Polydopamine-Supported Lipid Bilayers

    Science.gov (United States)

    Nirasay, Souryvanh; Badia, Antonella; Leclair, Grégoire; Claverie, Jerome P.; Marcotte, Isabelle

    2012-01-01

    We report the formation of lipid membranes supported by a soft polymeric cushion of polydopamine. First, 20 nm thick polydopamine films were formed on mica substrates. Atomic force microscopy imaging indicated that these films were also soft with a surface roughness of 2 nm under hydrated conditions. A zwitterionic phospholipid bilayer was then deposited on the polydopamine cushion by fusion of dimyristoylphosphatidylcholine (DMPC) and dioleoylphosphatidylcholine (DOPC) vesicles. Polydopamine films preserved the lateral mobility of the phospholipids as shown by fluorescence microscopy recovery after photobleaching (FRAP) experiments. Diffusion coefficients of ~5.9 and 7.2 µm2 s−1 were respectively determined for DMPC and DOPC at room temperature, values which are characteristic of lipids in a free standing bilayer system.

  3. The significant effect of heterojunction quality on photoelectrochemical water splitting in bilayer photoelectrodes: Rb(x)WO3 thin films on RbLaNb2O7 layers.

    Science.gov (United States)

    Nakajima, Tomohiko; Nakamura, Takako; Tsuchiya, Tetsuo

    2014-12-28

    We have prepared nearly perfect hexagonal m-plane-oriented RbxWO3 films on (010)-oriented RbLaNb2O7 layers. The prepared bilayer films showed Rb diffusion from the RbLaNb2O7 seed layers, and we obtained uniaxially oriented RbxWO3/Rb1-yLaNb2O7 photoanodes. The RbxWO3/Rb1-yLaNb2O7 bilayer photoanodes exhibited enhanced photoelectrochemical water splitting compared with the RbxWO3 and RbLaNb2O7 monolayer photoanodes. Furthermore, we clearly demonstrated that the high crystal quality of the heterojunction significantly enhanced water splitting. The photocurrent density of the nearly perfectly oriented RbxWO3/Rb1-yLaNb2O7 photoanode that we prepared was 9.4-fold that of an unoriented bilayer photoanode. This increase was attributed to the inhibition of photo-excited charge recombination and stimulated electron transfer derived from low grain-boundary resistance.

  4. An experimental investigation of innovative bridge columns with engineered cementitious composites and Cu-Al-Mn super-elastic alloys

    Science.gov (United States)

    Hosseini, F.; Gencturk, B.; Lahpour, S.; Ibague Gil, D.

    2015-08-01

    Recent strong earthquakes have shown that reinforced concrete (RC) bridge columns constructed using conventional materials and techniques suffer from major damage and permanent deformations. The yielding of the longitudinal reinforcement as the main source of energy absorption, and cracking and spalling of concrete results in a dysfunctional bridge structure that does not support the post-disaster recovery efforts. This paper investigates the use of engineered cementitious composites (ECCs) and Cu-Al-Mn super-elastic alloys (SEAs) to improve the performance of bridge columns under seismic loads. A new column design is proposed, which is composed of a pre-fabricated ECC tube that encompasses the longitudinal and transverse steel reinforcement (rebar). The rebar in the plastic hinge region of the cantilever columns was totally or partially replaced with Cu-Al-Mn SEA bars. The tube was filled with conventional concrete after it was placed inside the rebar cage of the foundation. ECC exhibits superior tensile ductility, bonding with steel, energy absorption and shear resistance, in addition to lower permeability and reduced crack widths compared to conventional concrete. Cu-Al-Mn SEA bars are capable of recovering large inelastic deformations exceeding 12% strain. The proposed approach capitalizes on the deformability of ECC with reduced damage, and the energy absorption capacity of Cu-Al-Mn SEA bars without permanent deformation. A total of six column specimens were constructed and tested under simulated seismic loading. The number of rebars replaced with Cu-Al-Mn SEA bars, ECC mixture design, and the ratio of the concrete core area to total column cross-sectional area were the variables investigated in the test program. A comparison of the results indicated that the proposed concept with no Cu-Al-Mn SEA bars provides higher lateral strength, similar energy absorption and reduced damage compared to conventional RC columns; however, similar to a conventional column, it

  5. Bi-layer channel structure-based oxide thin-film transistors consisting of ZnO and Al-doped ZnO with different Al compositions and stacking sequences

    Science.gov (United States)

    Cho, Sung Woon; Yun, Myeong Gu; Ahn, Cheol Hyoun; Kim, So Hee; Cho, Hyung Koun

    2015-03-01

    Zinc oxide (ZnO)-based bi-layers, consisting of ZnO and Al-doped ZnO (AZO) layers grown by atomic layer deposition, were utilized as the channels of oxide thin-film transistors (TFTs). Thin AZO layers (5 nm) with different Al compositions (5 and 14 at. %) were deposited on top of and beneath the ZnO layers in a bi-layer channel structure. All of the bi-layer channel TFTs that included the AZO layers showed enhanced stability (Δ V Th ≤ 3.2 V) under a positive bias stress compared to the ZnO single-layer channel TFT (Δ V Th = 4.0 V). However, the AZO/ZnO bi-layer channel TFTs with an AZO interlayer between the gate dielectric and the ZnO showed a degraded field effect mobility (0.3 cm2/V·s for 5 at. % and 1.8 cm2/V·s for 14 at. %) compared to the ZnO single-layer channel TFT (5.5 cm2/V·s) due to increased scattering caused by Al-related impurities near the gate dielectric/channel interface. In contrast, the ZnO/AZO bi-layer channel TFTs with an AZO layer on top of the ZnO layer exhibited an improved field effect mobility (7.8 cm2/V·s for 14 at. %) and better stability. [Figure not available: see fulltext.

  6. W/Al双层膜系的纳米压痕实验及有限元仿真%Nano-indentation experiment of W/Al bilayer-film system and its finite element simulation

    Institute of Scientific and Technical Information of China (English)

    尚帅华; 杨平; 李春

    2009-01-01

    采用磁控溅射法在CAT.No.7101玻璃基底上沉积了W/Al双层金属膜,并对其进行纳米压痕实验.利用非线性有限元法对压痕过程进行仿真,分析了膜基体系的应力分布.结果表明:磁控溅射法制备的薄膜组织均匀、力学性能好.W/Al双层金属膜系中的W薄膜的弹性模量与硬度平均值分别为75.433 5 GPa、6.206 GPa,其值与块状W材料的相应参数差别较大.仿真曲线与实验结果基本相符,能够反映出膜基体系的力学状态以及应力分布规律.%W/Al bilayer-metal films were deposited on CAT.NO.7101 glass substrates using the magnetron sputtering method. Nano-indentation test was performed on the observed film samples. The loading and unloading processes of nano-indentation tests were simulated via the non-linear finite element method, and the stress distribution in the film-substrate system was analyzed. The results show that W/Al films fabricated by the magnetron sputtering method exhibit uniform structure and good mechanical properties. The elastic modulus and the mean value of hardness of W film in the W/Al bilayer-metal films are 75.433 5 GPa and 6.206 GPa respectively, which are quite different from the corresponding parameters of bulk W. The simulation curves well agree with the experimental results and clearly reflect the mechanical states as well as stress distribution of the film-substrate system.

  7. KINETIKA MIKRO DEKOMPOSISI METANA MENJADI KARBON NANOTUBE PADA PERMUKAAN KATALIS Ni-Cu-Al

    Directory of Open Access Journals (Sweden)

    Praswasti Pembangun Dyah Kencana Wulan

    2012-04-01

    Full Text Available MICRO KINETICS OF DECOMPOSITION OF METHANE TO CARBON NANOTUBES OVER NI-CU-AL CATALYST. The main focus of this research was to obtain micro kinetics decomposition of methane producing carbon nanotube on the surface of the Ni-Cu-Al catalyst. Experimental kinetics data collected at a temperature range of 650-750oC and pressure of one atmosphere. The preliminary test was conducted to obtain the kinetics are not influenced by external and internal diffusion limitations as well as inter-phase transfer. Kinetics data were tested by micro kinetic model derived from the catalyst surface reaction mechanism. The most appropriate kinetic model becomes the rate-limiting step of methane decomposition reaction. Results of preliminary experiment showed that the kinetics of the external diffusion effect is negligible at flow rates above 150 mL/min. Internal diffusion can be ignored with a catalyst under 0.25 mm in diameter with a weight of 0.04 grams of catalyst and contact time 2.5x10-4. Rate equation analysis shows that the rate-limiting step is the adsorption which indicates that intermediate consumption (CH4I + I Û CH3I + HI is faster than the formation of intermediate (adsorption of methane, CH4 + I Û CH4I. The activation energy obtained for 34.628 kJ/mol and pre-exponential factor of 6.583x106.  Fokus utama penelitian ini adalah memperoleh kinetika mikro dekomposisi metana yang menghasilkan Carbon Nanotube pada permukaan  katalis Ni-Cu-Al. Data kinetika eksperimen diambil pada rentang temperatur 650-750oC dan tekanan 1 atmosfer. Percobaan pendahuluan dilakukan untuk memperoleh daerah kinetika yang tidak dipengaruhi oleh limitasi difusi eksternal dan internal serta perpindahan antar fasa.  Data kinetika  diuji dengan model kinetika mikro yang diturunkan dari mekanisme reaksi permukaan katalis. Model kinetika yang paling sesuai menjadi tahap pembatas laju reaksi dekomposisi metana. Hasil percobaan pendahuluan kinetika menunjukkan bahwa pengaruh

  8. Preparation of CuAlO2 and Photocatalytic Performance of Composite Catalysts%CuAlO2的合成及其复合催化剂的光催化性能

    Institute of Scientific and Technical Information of China (English)

    康园丽; 王桂赟; 刘宗园; 王延吉

    2012-01-01

    Delafossite CuA102 is prepared by thermal treatment the precursor obtained via a serai-wet method using Cu(N03)2 and A1(NO3)3 as raw material ,and oxalic acid as precipitant of copper ion under nitrogen atmosphere. The samples are characterized by thermal gravimetric analysis (TG), X-ray diffraction (XRD), ultraviolet visible diffuse reflectance(UV-Vis-DR) and transmission electron microscope(TEM). The formation process of the CuA102 is researched. With increasing the thermal treatment temperature of the precursor, firstly the CuO and Cu2O are generated, and then intermediate phase of CuAl2O4 appeared, finally no impurity phase CuA102 formed. The results shows that the synthesized CuA102 has good crystal perfection and its direct band gap is about 3.1 eV. The n-p composite photocatalysts W0rCuA102, Ti0rCuA102 and Zn0-CuA102 are prepared by precipitation composite method. The composite photocatalysts are characterized by XRD and TEM, and the photocatalytic performance of the catalysts are tested, and the results indicate that all the composite catalysts mentioned above are all made up two phases, and they all have photocatalytic activity for decomposing pure water into hydrogen under the UV-light irradiation.%以硝酸铜和硝酸铝为原料,草酸为铜离子的沉淀剂,半湿法制得前驱体,再于氮气气氛下热处理形成了铜铁矿结构的CuAlO2.对样品进行热失重(TG),X射线衍射(XRD),紫外-可见漫反射(UV-Vis-DR)及透射电镜(rEM)表征分析,探讨了CuAlO2的形成过程.结果显示,随着热处理温度的升高,含铜物质经历了由CuO、Cu2O到CuAl2O4,再到CuAlO2的变化历程;制得的CuAlO2晶体结晶完整性较好,直接禁带宽度为3.1 eV左右.用沉淀复合的方法制备出了n-p异质复合型光催化剂WO3-CuAlO2、TiO2-CuAlO2和ZnO-CuAlO2,对复合催化剂进行了XRD和TEM表征分析,并测试了复合催化剂的光催化活性.结果表明,上述催化剂均由两种物相复合而成,且在紫外光

  9. Ni-free Zr-Cu-Al-Nb-Pd bulk metallic glasses with different Zr/Cu ratios for biomedical applications.

    Science.gov (United States)

    Huang, Lu; Yokoyama, Yoshihiko; Wu, Wei; Liaw, Peter K; Pang, Shujie; Inoue, Akihisa; Zhang, Tao; He, Wei

    2012-08-01

    Zr-based bulk metallic glasses (BMGs) possess attractive properties for prospective biomedical applications. The present study designs Ni-free Zr-Cu-Al-Nb-Pd BMGs and investigates their in vitro biocompatibility by studying mechanical properties, bio-corrosion resistance, and cellular responses. The Ti-6Al-4V alloy is used as a reference material. It is found that the Zr-based BMGs exhibit good mechanical properties, including high strengths above 1600 MPa, high hardness over 4700 MPa, and low elastic moduli of 85-90 GPa. The Zr-based BMGs are corrosion resistant in a simulated body environment, as revealed by wide passive regions, low passive current densities, and high pitting overpotentials. The formation of ZrO(2)-rich surface passive films of the Zr-based BMGs contributes to their high corrosion resistance, whereas their pitting corrosion in the phosphate buffered saline solution can be attributed to the sensitivity of the ZrO(2) films to the chloride ion. The general biosafety of the Zr-based BMGs is revealed by normal cell adhesions and cell morphologies. Moreover, the Zr/Cu content ratio in the alloy composition affects the biocompatibility of the Zr-based BMGs, by increasing their corrosion resistance and surface wettability with the increase of the Zr/Cu ratio. Effects of Zr/Cu ratios can be used to guide the future design of biocompatible Zr-based BMGs. Copyright © 2012 Wiley Periodicals, Inc.

  10. The influence of Cu, Al, or Fe on the insulating capacity of CF3I

    Science.gov (United States)

    Xiao, Song; Cressault, Yann; Zhang, Xiaoxing; Teulet, Philippe

    2016-12-01

    SF6 is widely used in electrical equipment as an insulating medium. However, SF6 is a serious greenhouse gas. CF3I is considered as one of its potential alternatives. This study verifies whether free metal particle (Cu, Al, or Fe) defects adversely affect CF3I insulation and investigates the incidence from different types and numbers of metal particles. This study is also devoted to calculating specific heat at constant pressure and electrical conductivity of CF3I-metal mixtures. The calculation results prove that with the increase of metal ions, temperature rises faster in the CF3I-Cu plasma or in the CF3I-Fe plasma than in the CF3I plasma without metal absorbing the same energy. The fast development of ionization can promote the increase of free electrons and the rise of electric conductivity. On the basis of the experiments and theoretical analysis, the influence of Cu and Al on the insulating capacity of CF3I is greater than that of Fe.

  11. Crystal growth and transport properties of CuAlO2 single crystal

    Science.gov (United States)

    Brahimi, R.; Rekhila, G.; Trari, M.; Bessekhouad, Y.

    2014-12-01

    The transport properties of the delafossite CuAlO2 single crystal, grown by the flux method, are confined in ∞[AlO2] layers extending in the (001) plans. The dielectric properties are measured up to 490 K in the frequency range (102-105 Hz). The small variation of the dielectric loss tan(δ) is attributed to the wide space charge region. The linear plot log (conductivity) vs. 1000/ T follows an Arrhenius type law and the results are discussed in terms of electron hopping among localized states. The activation energy (0.18 eV) gives an effective mass of 16 m 0 indicating that the levels in the vicinity of the Fermi level are strongly localized. Hence, the increase of the conductivity (σ) results from a thermal activation of the mobility (μ300 K = 1.2 × 10-5 cm-2 V-1 s-1). The sign of hole like small polarons is that of p type carriers originating from oxygen intercalation. The thermopower is little temperature dependent and characteristic of non degenerate conductivity with a low holes concentration and a large concentration of surface states within the gap region.

  12. A free-cutting and ductile CuAlMnZnTiB shape memory alloy

    Institute of Scientific and Technical Information of China (English)

    刘娜; 李周; 李灵; 刘斌; 李擎天; 徐根应

    2015-01-01

    The mechanical properties and cutting performance of the designed CuAlMnZnTiB shape memory alloy were studied by tensile test and microstructure observation. Using X-ray diffractometry, differential scanning calorimetry (DSC) and semi-quantitative shape memory effect test, the microstructure and shape memory effect were analyzed. It is found that lots ofβ phase and fewα phase are formed in the quenching of Cu-7.5Al-9.7Mn-3.4Zn-0.3Ti-0.14B (mass fraction, %) alloy, a great deal of martensite and fewα phase are formed in the aging alloy, while the annealing alloy is composed of a great deal ofα phase and fewβ phase. The tensile strength and elongation of the annealed alloy are 649 MPa and 17.1%, respectively. Some tiny and dispersion distributed second phase particles are generated in Ti and B precipitates, greatly improving the alloy machinability.

  13. Accumulative Roll Bonding and Post-Deformation Annealing of Cu-Al-Mn Shape Memory Alloy

    Science.gov (United States)

    Moghaddam, Ahmad Ostovari; Ketabchi, Mostafa; Afrasiabi, Yaser

    2014-12-01

    Accumulative roll bonding is a severe plastic deformation process used for Cu-Al-Mn shape memory alloy. The main purpose of this study is to investigate the possibility of grain refinement of Cu-9.5Al-8.2Mn (in wt.%) shape memory alloy using accumulative roll bonding and post-deformation annealing. The alloy was successfully subjected to 5 passes of accumulative roll bonding at 600 °C. The microstructure, properties as well as post-deformation annealing of this alloy were investigated by optical microscopy, scanning electron microscopy, x-ray diffraction, differential scanning calorimeter, and bend and tensile testing. The results showed that after 5 passes of ARB at 600 °C, specimens possessed α + β microstructure with the refined grains, but martensite phases and consequently shape memory effect completely disappeared. Post-deformation annealing was carried out at 700 °C, and the martensite phase with the smallest grain size (less than 40 μm) was obtained after 150 s of annealing at 700 °C. It was found that after 5 passes of ARB and post-deformation annealing, the stability of SME during thermal cycling improved. Also, tensile properties of alloys significantly improved after post-deformation annealing.

  14. Superelastic behavior and damping capacity of CuAlBe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Montecinos, Susana [Universidad de Chile and CIMAT, Blanco Encalada 2008, Santiago (Chile); Moroni, Maria Ofelia [Universidad de Chile, Depto. de Ingenieria Civil, Casilla 228/3, Santiago (Chile)]. E-mail: mmoroni@cec.uchile.cl; Sepulveda, Aquiles [Universidad de Chile, Depto. de Ingenieria Mecanica, Casilla 2777, Santiago (Chile)

    2006-03-15

    Shape memory alloys (SMAs) showing the superelastic effect, dissipate energy through hysteretic cycles up to large strain amplitudes, without remnant strains after unloading. This effect is associated with a reversible stress-induced martensitic transformation. In this paper, the behavior of copper-based SMAs is examined, with the perspective of potential applications in seismic-energy dissipative devices. In particular, two different compositions of CuAlBe are characterized using chemical analysis, differential scanning calorimetry (DSC), light and scanning electron microscopy and X-rays diffraction. Mechanical and hysteretic damping properties are determined from cyclic tensile and tension-compression tests, for different strain amplitudes and frequencies. Both alloys show superelastic behavior, although hysteresis loops differ, due to differences in the composition and transformation phase temperatures. Equivalent damping up to 5% was obtained for the largest strain imposed. Frequency, in the range of interest for seismic applications, had a small influence on the damping values. It is concluded that alloy Cu-11.8 wt.% Al-0.5 wt.% Be best exhibited properties for the application intended.

  15. Numerical investigation on thermal properties at Cu-Al interface in micro/nano manufacturing

    Science.gov (United States)

    Zhang, Liqiang; Yang, Ping; Chen, Min; Liao, Ningbo

    2012-02-01

    A hybrid model by integrating TTM (two-temperature model) and MD (molecular dynamics) is proposed to investigate the properties on interface of dissimilar materials under thermal flux conditions. This model can describe the electron phonon coupling and phonon scattering at the interface of different metals easily. By comparing the Cu-Cu interface and Cu-Al interface, the atoms of the Cu-Cu interface at different sides tend to move together; while, the atoms displacements of Cu and Al are opposite along the interface, which may cause stress and voids at the interface. Moreover, the propagation mechanisms of nanocracks and the corresponding change of temperature distribution and thermal flux are investigated. The results show that the interfaces of dissimilar materials are prone to crack initiations, leading to delaminations because of the high temperature. All these are useful for understanding the deformation and failure of the interfaces structures. It implies a potential method for design and analysis of interface structure in micro/nano manufacturing.

  16. Research of Interaction Between Zn Based Solders and Cu, Al Substrates

    Directory of Open Access Journals (Sweden)

    Prach Michal

    2014-06-01

    Full Text Available The paper deals with the study of interaction between Cu, Al substrates (purity 5N and ZnAl4, ZnAg6Al6 zinc solders for higher application temperatures. Soldering was performed with power ultrasound in the air without flux application at temperature 420 °C. Acting time of ultrasonic vibration was 3 s and ultrasound frequency was 40 kHz. Soldered joints were assessed by optical light microscopy and EDX microanalysis. Intermetallic layers (IM CuZn4 and Cu5Zn8 were formed at the Cu/ZnAl4 boundary. The βZn-αAl mechanical mixture was formed at the Al/ZnAl4 boundary. AgZn3 and Cu5Zn8 IM layers were formed at the Cu/ZnAg6Al6 boundary, and mechanical mixture of βZn-αAl and AgZn3 intermetallic mixture were formed at the boundary Al/ZnAg6Al6.

  17. Reduced Cu concentration in CuAl-LPE-grown thin Si layers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T.H.; Ciszek, T.F.; Asher, S.; Reedy, R. [National Renewable Energy Lab., Golden, CO (United States)

    1995-08-01

    Cu-Al has been found to be a good solvent system to grow macroscopically smooth Si layers with thicknesses in tens of microns on cast MG-Si substrates by liquid phase epitaxy (LPE) at temperatures near 900{degrees}C. This solvent system utilizes Al to ensure good wetting between the solution and substrate by removing silicon native oxides, and employs Cu to control Al doping into the layers. Isotropic growth is achieved because of a high concentration of solute silicon in the solution and the resulting microscopically rough interface. The incorporation of Cu in the Si layers, however, was a concern since Cu is a major solution component and is generally regarded as a bad impurity for silicon devices due to its fast diffusivity and deep energy levels in the band gap. A study by Davis shows that Cu will nonetheless not degrade solar cell performance until above a level of 10{sup 17} cm{sup -3}. This threshold is expected to be even higher for thin layer silicon solar cells owing to the less stringent requirement on minority carrier diffusion length. But to ensure long term stability of solar cells, lower Cu concentrations in the thin layers are still preferred.

  18. On the comparison of the polarisation behaviour of exchange-biased AF/F NiMn/Fe 37Co 48Hf 15 bi-layer and multi-layer films with increased ferromagnetic cut-off frequencies

    Science.gov (United States)

    Seemann, K.; Leiste, H.; Krüger, K.

    2012-03-01

    Antiferromagnetic/ferromagnetic (AF/F) NiMn/Fe37Co48Hf15 films were investigated with respect to their exchange bias, in-plane unidirectional anisotropy, polarisation and high frequency behaviour. After deposition, carried out by r.f. magnetron sputtering, the films were post-annealed for 4 h at 300 °C in a static magnetic field, in order to induce exchange-bias, which results in a unidirectional anisotropy. Dependent on the presence of a bi-layer or multi-layer sandwich structure the films show a different exchange-bias field-ferromagnetic inter-layer thickness behaviour with exchange-bias fields μ0*Heb between 2 and 10 mT. The in-plane uniaxial (single film) or unidirectional anisotropy fields μ0*HUF were between 4 and 18 mT. This results in a significant increase of the cut-off frequency in the GHz range in comparison to a single Fe37Co48Hf15 film, which is shown by frequency-dependent permeability plots. High damping in the imaginary part of the permeability, i.e., high resonance line broadening could be observed for films with high coercivity μ0*Hc of around 7 mT in the easy axis of magnetisation.

  19. Breakdown of Shape Memory Effect in Bent Cu-Al-Ni Nanopillars: When Twin Boundaries Become Stacking Faults.

    Science.gov (United States)

    Liu, Lifeng; Ding, Xiangdong; Sun, Jun; Li, Suzhi; Salje, Ekhard K H

    2016-01-13

    Bent Cu-Al-Ni nanopillars (diameters 90-750 nm) show a shape memory effect, SME, for diameters D > 300 nm. The SME and the associated twinning are located in a small deformed section of the nanopillar. Thick nanopillars (D > 300 nm) transform to austenite under heating, including the deformed region. Thin nanopillars (D < 130 nm) do not twin but generate highly disordered sequences of stacking faults in the deformed region. No SME occurs and heating converts only the undeformed regions into austenite. The defect-rich, deformed region remains in the martensite phase even after prolonged heating in the stability field of austenite. A complex mixture of twins and stacking faults was found for diameters 130 nm < D < 300 nm. The size effect of the SME in Cu-Al-Ni nanopillars consists of an approximately linear reduction of the SME between 300 and 130 nm when the SME completely vanishes for smaller diameters.

  20. Distribution of distances between dislocations in different types of dislocation substructures in deformed Cu-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Trishkina, L., E-mail: trishkina.53@mail.ru; Zboykova, N.; Koneva, N., E-mail: koneva@tsuab.ru; Kozlov, E. [Tomsk State University of Architecture and Building, 2 Solyanaya St., Tomsk, 634003 (Russian Federation); Cherkasova, T. [Tomsk State University of Architecture and Building, 2 Solyanaya St., Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 50 Lenin Ave., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The aim of the investigation was the determination of the statistic description of dislocation distribution in each dislocation substructures component forming after different deformation degrees in the Cu-Al alloys. The dislocation structures were investigated by the transmission diffraction electron microscopy method. In the work the statistic description of distance distribution between the dislocations, dislocation barriers and dislocation tangles in the deformed Cu-Al alloys with different concentration of Al and test temperature at the grain size of 100 µm was carried out. It was established that the above parameters influence the dislocation distribution in different types of the dislocation substructures (DSS): dislocation chaos, dislocation networks without disorientation, nondisoriented and disoriented cells, in the walls and inside the cells. The distributions of the distances between dislocations in the investigated alloys for each DSS type formed at certain deformation degrees and various test temperatures were plotted.

  1. Structural Origin of the Enhanced Glass-Forming Ability Induced by Microalloying Y in the ZrCuAl Alloy

    Directory of Open Access Journals (Sweden)

    Gu-Qing Guo

    2016-03-01

    Full Text Available In this work, the structural origin of the enhanced glass-forming ability induced by microalloying Y in a ZrCuAl multicomponent system is studied by performing synchrotron radiation experiments combined with simulations. It is revealed that the addition of Y leads to the optimization of local structures, including: (1 more Zr-centered and Y-centered icosahedral-like clusters occur in the microstructure; (2 the atomic packing efficiency inside clusters and the regularity of clusters are both enhanced. These structural optimizations help to stabilize the amorphous structure in the ZrCuAlY system, and lead to a high glass-forming ability (GFA. The present work provides an understanding of GFAs in multicomponent alloys and will shed light on the development of more metallic glasses with high GFAs.

  2. Effect of nickel content on the electrochemical behavior of Cu-Al-Ni alloys in chloride free neutral solutions

    Energy Technology Data Exchange (ETDEWEB)

    Badawy, W.A., E-mail: wbadawy50@hotmail.co [Chemistry Department, Faculty of Science, Cairo University, 12 613 Giza (Egypt); El-Rabiee, M.M.; Helal, N.H.; Nady, H. [Chemistry Department, Faculty of Science, Fayoum University, Fayoum (Egypt)

    2010-12-30

    The electrochemical behavior of Cu-Al-Ni alloys in chloride free neutral solutions was investigated. The effect of Ni content on the corrosion resistance of the alloys was examined and evaluated. Conventional electrochemical techniques and electrochemical impedance spectroscopy, EIS, have been used. Potentiodynamic measurements revealed that the increase in the Ni content decreases the stability of the Cu-Al-Ni alloys. The polarization measurements were confirmed by EIS experiments. The morphology of the alloy surface was investigated by scanning electron microscopy, SEM, and surface analysis was made by energy dispersive X-ray technique. The experimental impedance data were fitted to theoretical data according to a proposed equivalent circuit model representing the electrode/electrolyte interface. The results of these experiments are discussed in reference to the potential-pH (Pourbaix) diagrams of the alloying elements.

  3. A Cu/Al-MCM-41 mesoporous molecular sieve: application in the abatement of no in exhaust gases

    Directory of Open Access Journals (Sweden)

    M. S. Batista

    2005-09-01

    Full Text Available Propane oxidation and reduction of NO to N2 with propane under oxidative conditions on a Cu-Al-MCM-41 mesoporous molecular sieve and Cu-ZSM-5 zeolites were studied. Both types of catalysts were prepared by ion exchange in aqueous solutions of copper acetate and characterised by X-ray diffraction (XRD, nitrogen sorption measurement, diffuse reflectance ultra-violet spectroscopy (DRS-UV, diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS of the adsorption of CO on Cu+ and temperature-programmed reduction with hydrogen (H2-TPR. The NO reduction was performed between 200 and 500 ºC using a GHSV = 42,000 h-1. H2-TPR data showed that in the prepared Cu-Al-MCM-41 all the Cu atoms are on the surface of the mesopores as highly dispersed CuO, which results in a decrease in specific surface area and in mesopore volume. H2-TPR together with DRIFTS data provided evidence that in Cu/ZSM-5 catalysts, Cu atoms are found as two different Cu2+ cations: Cualpha2+ and Cubeta2+, which are located on charge compensation sites, and their thermo-redox properties were different from those of Cu atoms in Cu-Al-MCM-41. The specific activity of the Cu2+ exchangeable cations in Cu-ZSM-5, irrespective of their nature, was much greater than that of the Cu2+ in Cu-Al-MCM-41, where they are found as CuO.

  4. Synthesis and characterization of CdS/CuAl2O4 core-shell: application to photocatalytic eosin degradation

    Science.gov (United States)

    Bellal, B.; Trari, M.; Afalfiz, A.

    2015-08-01

    The advantages of the hetero-junction CdS/CuAl2O4 for the photocatalytic eosin degradation are reported. Composite semiconductors are elaborated by co-precipitation of CdS on the spinel CuAl2O4 giving a core-shell structure with a uniform dispersion and intimate contact of the spinel nanoparticles inside the hexagonal CdS. The Mott-Schottky plots ( C -2- V) of both materials show linear behaviors from which flat band potentials are determined. The photoactivity increases with increasing the mass of the sensitizer CdS and the best performance is achieved on CdS/CuAl2O4 (85 %/15 %). The pH has a strong influence on the degradation and the photoactivity peaks at pH 7.78. The dark adsorption eosin is weak (~4 %), hence the change in the eosin concentration is attributed to the photocatalytic process. The degradation follows a zero-order kinetic with a rate constant of 5.2 × 10-8 mol L-1 mn-1 while that of the photolysis is seven times lower (0.75 × 10-8 mol L-1 mn-1).

  5. Lipid bilayers and interfaces

    NARCIS (Netherlands)

    Kik, R.A.

    2007-01-01

    In biological systems lipid bilayers are subject to many different interactions with other entities. These can range from proteins that are attached to the hydrophilic region of the bilayer or transmembrane proteins that interact with the hydrophobic region of the lipid bilayer. Interaction between

  6. Processus de réorientation des variantes de martensite dans un monocristal de Cu Al NiReorientation process of martensite variants in a Cu Al Ni monocrystal

    Science.gov (United States)

    Blanc, Pascal; Lexcellent, Christian

    2003-04-01

    On the one hand, Chu (Thesis, Minnesota, 1993), Abeyaratne et al. (Philos. Mag. A 73 (2) (1996) 457-497) performed biaxial tensile tests on a single crystal Cu-Al-Ni plate, in order to analyze the reorientation process of martensite variants. On the other hand, use is made of a constitutive model with n+1 internal variables (the volume fractions of austenite and of the n martensite variants) specific to the thermomechanical behavior of SMA single crystals in order to simulate the martensite variant reorientation. The comparison between experimental results and model prediction is fairly good. To cite this article: P. Blanc, C. Lexcellent, C. R. Mecanique 331 (2003).

  7. Study on Mechanics Performance of Cu-Al-Ni Shape Memory Alloys Prepared by Ohno Continuous Casting Process%热型连铸制备Cu-Al-Ni形状记忆合力学性能研究

    Institute of Scientific and Technical Information of China (English)

    杨少锋; 曹玉梅; 许广济; 张穗萌

    2007-01-01

    在自制的水平热型连铸设备(OCC)上,采用一定的工艺参数,制备出表面呈镜面,内部组织沿轴向定向排列的柱状组织Cu-Al-Ni形状记忆合金.其与金属型、定向凝固生产的样品相比,屈服强度、伸长率有一定的提高,伸长率可达12.8%.

  8. Effect of thickness on the stress and magnetoelectric coupling in bilayered Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3}-CoFe{sub 2}O{sub 4} films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing, E-mail: wang-jing@nuaa.edu.cn, E-mail: cwnan@tsinghua.edu.cn [State Key Laboratory of Mechanics and Control of Mechanical Structures, College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Li, Zheng; Wang, Jianjun; Nan, Cewen, E-mail: wang-jing@nuaa.edu.cn, E-mail: cwnan@tsinghua.edu.cn [School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China); He, Hongcai [State Key Lab of Electronic Thin Films and Integrated Devices, School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China)

    2015-01-28

    Magnetoelectric bilayered Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3}-CoFe{sub 2}O{sub 4}(PZT-CFO) films with different PZT thicknesses were grown on (111)Pt/Ti/SiO{sub 2}/Si substrates using chemical solution spin-coating. Structural characterization by X-ray diffraction and electron microscopy shows pure phases and well-defined interfaces between the PZT and CFO films. The CFO-PZT-substrate structure effectively alleviates the substrate clamping effect for the CFO layer, showing appreciable magnetoelectric responses in the composite films. Both the direct magnetoelectric effect and the magnetic field-induced Raman shifts in the A{sub 1}(TO{sub 1}) soft mode of PZT demonstrate the magnetic-mechanical-electric coupling in the films. The results also indicate that with a constant CFO layer thickness, the thickness of the PZT layer plays an important role in the stress relaxation and strong magnetoelectric coupling. The coupling could be further enhanced by increasing the CFO thickness, optimizing the volume (thickness) fraction of the PZT thickness, and releasing the clamping effect from the substrate.

  9. Cu-Al-O Nanofi bers Fabricated by Electrospinning and Their Ozone Sensing Properties at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    L Mo; CAO Jiajia; WANG Yu; SHEN Hongzhi; WANG Yiding

    2015-01-01

    Cu-Al-O nanofibers are synthesized by an electrospinning method. After electrospinning process, these nanofi bers were thermally treated at different temperatures from 900 to 1 100ć. The morphology and crystal structure of thefi bers were analyzed by scanning electron microscopy and X-ray diffraction. Thick fi lm gas sensors were fabricated by spinning the nanofi bers on a ceramic substrate with Au-Pt interdigitated electrodes. These sensors exhibited high ozone sensing properties at room temperature. When the sensors were exposed to 100 ppm ozone, the response time was about 2.74 s, and the recovery was about 12.68 s.

  10. Elastic anisotropy and low-temperature thermal expansion in the shape memory alloy Cu-Al-Zn.

    Science.gov (United States)

    Kuruvilla, Santhosh Potharay; Menon, C S

    2008-04-01

    Cu-based shape memory alloys are known for their technologically important pseudo-elastic and shapememory properties, which are intimately associated with the martensitic transformation. A combination of deformation theory and finite-strain elasticity theory has been employed to arrive at the expressions for higher order elastic constants of Cu-Al-Zn based on Keating's approach. The second- and third-order elastic constants are in good agreement with the measurements. The aggregate elastic properties like bulk modulus, pressure derivatives, mode Grüneisen parameters of the elastic waves, low temperature limit of thermal expansion, and the Anderson-Grüneisen parameter are also presented.

  11. TEM characterization of Al-C-Cu-Al{sub 2}O{sub 3} composites produced by mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Santos-Beltran, A. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, C.P. 31109, Chihuahua, Chih. (Mexico); Gallegos-Orozco, V. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, C.P. 31109, Chihuahua, Chih. (Mexico); Estrada-Guel, I. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, C.P. 31109, Chihuahua, Chih. (Mexico); Bejar-Gomez, L. [Universidad Mich. de San Nicolas de Hidalgo, Edif. ' W' , C.U., C.P. 58000, Morelia, Mich. (Mexico); Espinosa-Magana, F. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, C.P. 31109, Chihuahua, Chih. (Mexico); Miki-Yoshida, M. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, C.P. 31109, Chihuahua, Chih. (Mexico); Martinez-Sanchez, R. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, C.P. 31109, Chihuahua, Chih. (Mexico)]. E-mail: roberto.martinez@cimav.edu.mx

    2007-05-31

    Novel Al-based composites (Al-C-Cu-Al{sub 2}O{sub 3}) obtained by mechanical milling (MM), were characterized by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). Analyses of composites were carried out in both, the as-milled and the as-sintered conditions. C nanoparticles were found in the as-milled condition and Al{sub 2}O{sub 3} nanofibers were found in as-sintered products, as determined by EELS. C and Cu react with Al to crystallize in Al{sub 3}C{sub 4} and Al{sub 2}Cu structures, respectively.

  12. Nonlocal superelastic model of size-dependent hardening and dissipation in single crystal Cu-Al-Ni shape memory alloys.

    Science.gov (United States)

    Qiao, Lei; Rimoli, Julian J; Chen, Ying; Schuh, Christopher A; Radovitzky, Raul

    2011-02-25

    We propose a nonlocal continuum model to describe the size-dependent superelastic effect observed in recent experiments of single crystal Cu-Al-Ni shape memory alloys. The model introduces two length scales, one in the free energy and one in the dissipation, which account for the size-dependent hardening and dissipation in the loading and unloading response of micro- and nanopillars subject to compression tests. The information provided by the model suggests that the size dependence observed in the dissipation is likely to be associated with a nonuniform evolution of the distribution of the austenitic and martensitic phases during the loading cycle.

  13. Comportamiento a fractura de aleaciones pulvimetalúrgicas de Cu-Al-Ni con efecto memoria de forma

    Directory of Open Access Journals (Sweden)

    Rodríguez, P. P.

    2001-04-01

    Full Text Available Polycrystalline Cu-Al-Ni shape memory alloys have been scarcely employed for technological applications due to their high brittleness. The development of a new elaboration technique based on powder metallurgy has recently overcome this problem, through the improvement of the ductility of the produced alloy without affecting its shape memory properties. The fracture behaviour of an alloy obtained using this elaboration technique has been studied by means of Scanning Electron Microscopy and mechanical testing. The results show a ductile fracture with a maximum strain close to 13%, which is the best fracture behaviour obtained for Cu-Al-Ni polycrystals. The microstructure of such alloy has been studied by means of Transmission Electron Microscopy, showing a poligonyzed structure in which martensite plates passing through the subboundaries easily.

    La utilización de aleaciones policristalinas de Cu-Al-Ni con memoria de forma para aplicaciones tecnológicas había resultado tradicionalmente problemática debido a su elevada fragilidad. Este problema ha sido superado recientemente gracias a la introducción de un nuevo método de elaboración basado en la aplicación de las técnicas pulvimetalúrgicas, que permite aumentar la ductilidad de la aleación resultante sin afectar a sus propiedades de memoria de forma. Se ha estudiado mediante Microscopía Electrónica de Barrido y ensayos mecánicos el comportamiento a fractura de una aleación obtenida mediante este método de elaboración, observándose una fractura dúctil para una deformación próxima al 13%, lo que supone un mejor comportamiento que el observado en todos los trabajos realizados en policristales de Cu-Al-Ni. La microestructura de dicha aleación ha sido estudiada mediante Microscopía Electrónica de Transmisión, observándose que se encuentra poligonizada y que las plaquetas de martensita atraviesan fácilmente las sub juntas.

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

    Science.gov (United States)

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

    2015-03-01

    Lead-free solder alloys Sn-Cu (SC) and Sn-Ag-Cu (SAC) are widely used by the microelectronics industry, but enhanced control of the microstructure is needed to improve solder performance. For such control, nucleation and stability of Cu-Al intermetallic compound (IMC) solidification catalysts were investigated by variation of the Cu (0.7-3.0 wt.%) and Al (0.0-0.4 wt.%) content of SC + Al and SAC + Al alloys, and of SAC + Al ball-grid array (BGA) solder joints. All of the Al-modified alloys produced Cu-Al IMC particles with different morphologies and phases (occasionally non-equilibrium phases). A trend of increasing Cu-Al IMC volume fraction with increasing Al content was established. Because of solidification of non-equilibrium phases in wire alloy structures, differential scanning calorimetry (DSC) experiments revealed delayed, non-equilibrium melting at high temperatures related to quenched-in Cu-Al phases; a final liquidus of 960-1200°C was recorded. During cooling from 1200°C, the DSC samples had the solidification behavior expected from thermodynamic equilibrium calculations. Solidification of the ternary alloys commenced with formation of ternary β and Cu-Al δ phases at 450-550°C; this was followed by β-Sn, and, finally, Cu6Sn5 and Cu-Al γ1. Because of the presence of the retained, high-temperature phases in the alloys, particle size and volume fraction of the room temperature Cu-Al IMC phases were observed to increase when the alloy casting temperature was reduced from 1200°C to 800°C, even though both temperatures are above the calculated liquidus temperature of the alloys. Preliminary electron backscatter diffraction results seemed to show Sn grain refinement in the SAC + Al BGA alloy.

  15. Orientation-modulated exchange coupling in La0.67Ca0.33MnO3/CaMnO3 bilayer films

    Science.gov (United States)

    Wang, F.; Bai, Y.; Liu, W.; Zhang, H. R.; Li, S. K.; Dai, Z. M.; Ma, S.; Zhao, X. G.; Wang, S. C.; Wang, Z. J.; Zhang, Z. D.

    2017-04-01

    Epitaxial La0.67Ca0.33MnO3/CaMnO3 (LCMO/CMO) bilayers and the reference single layers were deposited by pulsed laser deposition on (001)- and (110)-oriented SrTiO3 (STO) substrates, allowing us to perform a detailed study of the dependence of exchange coupling on crystal orientations. It is found that the exchange bias (coercive) field of the (110)-oriented LCMO/CMO bilayer are decreased (increased) compared to that of (001)-oriented bilayer, due to the enhanced (weakened) Mn3+-Mn4+ ferromagnetic double-exchange interaction of LCMO layer. It is clear that the spin flop coupling that leads to the enhanced coercivity and the spin glass state that results in the exchange bias effect can coexist and are determined by the competition between Mn3+-Mn4+ ferromagnetic double-exchange and Mn4+-Mn4+ antiferromagnetic super-exchange interactions at the interface. We propose that strong Mn3+-Mn4+ ferromagnetic double-exchange interaction facilitates the existence of spin flop coupling, not the formation of spin glass state at the LCMO/CMO interface.

  16. Adsorption and subsequent partial photodegradation of methyl violet 2B on Cu/Al layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Guzmán-Vargas, Ariel, E-mail: aguzmanv@ipn.mx [Instituto Politécnico Nacional, ESIQIE-SEPI-DIQI, Laboratorio de Investigación en Materiales Porosos, Catálisis Ambiental y Química Fina (LiMpCa-QuF), UPALM Edif. 7 P.B. Zacatenco, GAM, México, D.F.07738 (Mexico); Lima, Enrique [Instituto de Investigaciones en Materiales-UNAM, Circuito exterior s/n, Cd. Universitaria, Del. Coyoacán, México, D.F. 04510 (Mexico); Uriostegui-Ortega, Gisselle A. [Instituto Politécnico Nacional, ESIQIE-SEPI-DIQI, Laboratorio de Investigación en Materiales Porosos, Catálisis Ambiental y Química Fina (LiMpCa-QuF), UPALM Edif. 7 P.B. Zacatenco, GAM, México, D.F.07738 (Mexico); Oliver-Tolentino, Miguel A. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Calzada Legaria 694, Col. Irrigación, México, D.F. 11500 (Mexico); Rodríguez, Esaú E. [Departamento de Química, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2580, Col. San Pedro Zacatenco, México, D.F. 07360 (Mexico)

    2016-02-15

    Graphical abstract: - Highlights: • LDH Cu/Al material showed high adsorption capacity. • Adsorption occurs by π–π interactions from the aromatic ring on the surface. • Adsorption mechanism fits to pseudo-second order model. • The photodegradation is due to the ·OH radical formation. - Abstract: Uncalcined Cu/Al LDH was studied as adsorbent and photocatalyst in the adsorption and subsequent photodegradation of methyl violet 2B dye (MV2B). Physicochemical characterization was carried out by XRD, FTIR, UV–vis, including photoactive properties, DSC/TGA and SEM. Kinetic and thermodynamic models showed great affinity and sorption capacity, the maximum adsorption capacity was 361.0 mg g{sup −1} obtained by Langmuir model, in addition, the results showed that the dye was adsorbed on the LDH surface. Photocatalytic activity was evaluated in the MV2B dye photodegradation process, and it was confirmed by the presence ·OH radicals monitored by EPR spin trapping technique, additionally, COD and TOC parameters were measured, {sup 13}C NMR showed differences for the adsorbed and photodegraded samples.

  17. Fabrication of Copper-Rich Cu-Al Alloy Using the Wire-Arc Additive Manufacturing Process

    Science.gov (United States)

    Dong, Bosheng; Pan, Zengxi; Shen, Chen; Ma, Yan; Li, Huijun

    2017-09-01

    An innovative wire-arc additive manufacturing (WAAM) process is used to fabricate Cu-9 at. pct Al on pure copper plates in situ, through separate feeding of pure Cu and Al wires into a molten pool, which is generated by the gas tungsten arc welding (GTAW) process. After overcoming several processing problems, such as opening the deposition molten pool on the extremely high-thermal conductive copper plate and conducting the Al wire into the molten pool with low feed speed, the copper-rich Cu-Al alloy was successfully produced with constant predesigned Al content above the dilution-affected area. Also, in order to homogenize the as-fabricated material and improve the mechanical properties, two further homogenization heat treatments at 1073 K (800 °C) and 1173 K (900 °C) were applied. The material and mechanical properties of as-fabricated and heat-treated samples were compared and analyzed in detail. With increased annealing temperatures, the content of precipitate phases decreased and the samples showed gradual improvements in both strength and ductility with little variation in microstructures. The present research opened a gate for in-situ fabrication of Cu-Al alloy with target chemical composition and full density using the additive manufacturing process.

  18. Processing of CuAlMn Shape Memory Foams with Open Spherical Pores by Silica-Gel Beads Infiltration Method

    Science.gov (United States)

    Li, Hua; Yuan, Bin; Gao, Yan

    2016-10-01

    A molten metal infiltration process with amorphous SiO2 (silica-gel) beads as space holders was used to prepare Cu-based shape memory foams in this article. We found that the silica-gel beads with micropores inside expanded when being heated to elevated temperatures and that proper control of the expansion of silica-gel beads helped form necks between the beads with different bonding extent, which had been taken advantage of to have a good control of the foam morphology and porosity, by carefully designing suitable procedures and choosing proper parameters for the process. In addition, we studied in detail the effect of heating temperature, silica-gel bead density, and infiltration pressure of the present process on the morphology and porosity of CuAlMn shape memory foams. By coordinating these three key parameters, CuAlMn shape memory foams with open spherical pores and adjustable porosity from 66 to 85 pct were reliably produced.

  19. Effect of elemental interaction on microstructure and mechanical properties of FeCoNiCuAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Y.X., E-mail: yxzhuang@epm.neu.edu.cn [Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China); Liu, W.J.; Chen, Z.Y.; Xue, H.D.; He, J.C. [Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China)

    2012-10-30

    FeCoNiCuAlX (X refers to Si, Cr, Ti, Zr and Nd) alloys were prepared using a suck-casting method. The effect of various elements on phase constituents, microstructures and mechanical properties of the alloys was investigated using X-ray diffraction (XRD), scanning electron microscopy, and compressive tests. It has been found that the microstructure and phase constituents remain unchanged when the Si, Cr and Ti are added into the FeCoNiCuAl alloy, which have a typical cast dendrite microstructure consisting of a dominated body-centered-cubic (BCC) solid solution and a face-centered-cubic (FCC) solid solution. However, the intermetallic compounds are formed in the alloys with the addition of Zr or Nd element. The compressive strength and plasticity of the alloys are enhanced by the addition of the Si, Cr and Ti, and retarded by the addition of the Zr or Nd element. The results have been discussed in aspects of atomic size difference, electronegativity difference, valance electron concentration and the mixing enthalpy among the elements in the alloys.

  20. Ultrasonic characterization of Cu-Al-Ni single crystals lattice stability in the vicinity of the phase transition.

    Science.gov (United States)

    Landa, Michal; Novák, Václav; Sedlák, Petr; Sittner, Petr

    2004-04-01

    Measurements of elastic constants of the austenite phase when approaching the phase transformation either upon cooling or stressing is of the crucial interest for the shape memory alloy field. Acoustic properties (wave velocity and also attenuation changes) of the Cu-Al-Ni single crystal were investigated in situ during stress-induced martensitic transformation at constant (room) temperature. The parent austenite cubic lattice of the Cu-Al-Ni exhibits very high elastic anisotropy (anisotropy factor A approximately 12). The measurements were made using nine combinations of (i) applied uniaxial compression in a given crystal direction, (ii) the wave propagation and (iii) polarization vectors. The chosen configurations are sufficient for evaluation of all independent third order elastic constants (TOEC). The longitudinal modes were also measured by the immersion technique, using the transducer pair in a water tank installed on the testing machine. The device works as "a ultrasonic extensometer" measuring a transverse strain of the specimen. The dependencies of both natural and initial wave velocities on the applied stress may be evaluated. Three elastic constants of the stress-induced martensite were determined. The elastic properties were found to vary with the increasing stress above the Ms transformation temperature, which is interpreted as a precursor for the martensitic transformation. The onset of the transformation was additionally identified from the acoustic emission measurement.

  1. Development of in-Situ Al-Si/CuAl2 Metal Matrix Composites: Microstructure, Hardness, and Wear Behavior

    Directory of Open Access Journals (Sweden)

    Mahmoud M. Tash

    2016-06-01

    Full Text Available In the present work, in-situ metal matrix composites were fabricated through squeeze casting. The copper particles were dispersed with different weight percentages (3%, 6%, 10%, and 15% into Al-12% Si piston alloy. Also, heat treatments were performed at 380 °C and 450 °C for holding times of 6 and 18 h. The microstructures, X-ray diffractometer (XRD pattern, hardness, and wear characteristics were evaluated. The results showed that these copper particles have reacted with the aluminum under all of the aforementioned processing conditions resulting in the formation of fine copper aluminide intermetallics. Most of the intermetallics were CuAl2, while AlCu appeared in a small ratio. Additionally, these intermetallics were homogenously distributed within the alloy matrix with up to 6% Cu addition. The amounts of those intermetallics increased after performing heat treatment. Most of these intermetallics were CuAl2 at 380 °C, while the Cu-rich intermetallics appeared at 450 °C. Increasing the holding time to 18 h, however, led to grain coarsening and resulted in the formation of some cracks. The hardness of the resulting composite materials was improved. The hardness value reached to about 170 HV after heat treating at 380 °C for 8 h. The wear resistance of the resulting composite materials was remarkably improved, especially at lower additions of Cu and at the lower heat treatment temperature.

  2. Development of in-Situ Al-Si/CuAl2 Metal Matrix Composites: Microstructure, Hardness, and Wear Behavior

    Science.gov (United States)

    Tash, Mahmoud M.; Mahmoud, Essam R. I.

    2016-01-01

    In the present work, in-situ metal matrix composites were fabricated through squeeze casting. The copper particles were dispersed with different weight percentages (3%, 6%, 10%, and 15%) into Al-12% Si piston alloy. Also, heat treatments were performed at 380 °C and 450 °C for holding times of 6 and 18 h. The microstructures, X-ray diffractometer (XRD) pattern, hardness, and wear characteristics were evaluated. The results showed that these copper particles have reacted with the aluminum under all of the aforementioned processing conditions resulting in the formation of fine copper aluminide intermetallics. Most of the intermetallics were CuAl2, while AlCu appeared in a small ratio. Additionally, these intermetallics were homogenously distributed within the alloy matrix with up to 6% Cu addition. The amounts of those intermetallics increased after performing heat treatment. Most of these intermetallics were CuAl2 at 380 °C, while the Cu-rich intermetallics appeared at 450 °C. Increasing the holding time to 18 h, however, led to grain coarsening and resulted in the formation of some cracks. The hardness of the resulting composite materials was improved. The hardness value reached to about 170 HV after heat treating at 380 °C for 8 h. The wear resistance of the resulting composite materials was remarkably improved, especially at lower additions of Cu and at the lower heat treatment temperature. PMID:28773564

  3. Asymmetric Magnetization Reversal Probed by Recoil Loop Measurements in an Exchange QBiased La0.67Sr0.33MnO3/La0.33Ca0.67MnO3 Bilayer Film

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-Hong; H.-U.HABERMEIER; G.CRISTIANI; SUN Ji-Rong; SHEN Bao-Gen

    2008-01-01

    We exploit the recoil loop measurements to study the asymmetric magnetization reversal in an exchange-biased La0.37Sr0.33MnO3/La0.33 Ca0 67MnO3 bilayer film.It is found that the recoil curve encloses a marked area only in the second quadrant of the hysteresis loop,and the recoil susceptibility in the descending branch of the major loop is evidently higher than that in the ascending branch.The study indicates that the exchange anisotropy of a unidirectional nature and an orientation deviated from the easy axis of the ferromagnetic layer plays a crucial role in creating the reversal asymmetry.

  4. Mechanical and Memory Performance of CuAlNi Shape Memory Alloy Wires Cast by Ohno Continuous Casting Process%热型连铸CuAlNi形状记忆合金丝的性能研究

    Institute of Scientific and Technical Information of China (English)

    尹占华; 黎沃光; 余业球

    2004-01-01

    用热型连铸法制取φ1.5mm的柱晶CuAlNi合金丝,具有轴向排列的柱晶组织.经过900℃固溶处理,拉伸曲线与单晶的相似,具有两个阶段的马氏体转变,抗拉强度可达633MPa,延伸率14.95%.在4%的固定应变下,反复拉伸疲劳断裂次数高达38560次,形状回复率为100%.反复拉伸后在晶界上形成一种新相,有效地松弛了晶界上的应力集中,可能是疲劳寿命大幅度提高的原因.

  5. Forças de Corte Geradas por Torneamento um Estudo de Caso das Ligas Cu-Al-Be e Cu-Al-Be-Nb-Ni Passíveis do Efeito Memória de Forma

    OpenAIRE

    2014-01-01

    As ligas com memória de forma, mais especificamente as constituídas de CuAlBe, têm desempenhado um papel importante na fabricação de componentes eletromecânicos, sobretudo quando trabalhados a partir de solicitações térmicas e/ou tensões aplicadas. A princípio, neste presente trabalho de pesquisa, foram obtidas, por fundição a gás, amostras das ligas Cu-11,8%Al-0,60%Be; Cu-11,8%Al-0,55%Be; Cu-11,8%Al-0,55%Be-0,50%Nb-0,27%Ni (% em peso). Sequencialmente, temperou-se a metade delas, com o intui...

  6. Preparation and Mechanical Characterization of Cu-Al2O3 Functionally Graded Material for electrical contact applications

    Directory of Open Access Journals (Sweden)

    Abdul Raheem. K. Abid Ali

    2017-07-01

    Full Text Available In this study, five-layered stepwise Cu/Al2O3 as functionally graded materials have been prepared from copper powder with with five percentage of alumina powder as (5 ,10 ,20 ,30 and 40 Wt% by using powder metallurgy technique. Mixing of copper (34.32 µm and alumina (1.439 µm powders for two hours and then several disk sample with dimensions (14mm diameter and 10 thickness have been compacting at different compacting stresses (550, 650 and 750 MPa. However, sintering of specimens for three hours at 850 under vacuum about has been achieved. The Porosity and density before and after sintering have been calculated. X-ray diffraction analysis showed that tests before and after sintering is similar, there is no new phase formed after sintering. Scanning electron microscopy technique is used to characterize the surface of each layer. Hardness test showed slight linear graded microhardness across the layers without any obvious jumps throughout the thickness. Pin on disc method have been used in determining the wear or material removal of prepared FGM samples. In addition, it was examined thermal conductivity and the electrical resistance have been done in preparing samples from composite and functionally graded material. From the experimental results, it is clear that hardness results change in each layer by producing FGM according to the percentage of the harder constituent (i.e. Al2O3 from 53 to 113 Hv. While Thermal conductivity decrease with the increasing addition weight percentage for α-Al2O3. And Electrical resistance increased when alumina content increased for (5% to 40%. Wear rate improved with the increasing additive percentage of alumina from 0.507 for layer 1 to 0.15 for layer five at 15N and 25 min. Smoothly gradual change of the composition in the Cu/Al2O3 FGM can eliminate the microscopic interface, such as a result as that traditional Cu-Al2O3 joint.

  7. Theoretical investigations on magnetic entropy change in amorphous and crystalline systems: Applications to RAg (R=Tb, Dy, Ho) and GdCuAl

    Energy Technology Data Exchange (ETDEWEB)

    Ranke, P.J. von, E-mail: von.ranke@uol.com.br [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Nóbrega, E.P. [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Caldas, A. [Sociedade Unificada de Ensino Superior e Cultura, SUESC, 20211-351 Rio de Janeiro, RJ (Brazil); Alho, B.P. [Instituto de Aplicação Fernando Rodrigues da Silveira, Universidade do Estado do Rio de Janeiro, Rua Santa Alexandrina, 288, 20260-232 RJ (Brazil); Ribeiro, P.O.; Alvarenga, T.S.T.; Lopes, P.H.O.; Sousa, V.S.R. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Síncrotron, CNPEM, 13083-970 Campinas, SP (Brazil); Oliveira, N.A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro – UERJ, Rua São Francisco Xavier, 524, 20550-013 RJ (Brazil)

    2014-11-15

    We report theoretical investigations on the magnetic entropy changes in amorphous systems through two different assumptions. In the first assumption, the HPZ-anisotropic model is considered to deal with the random direction of magnetic moments, where the amorphous RAg (R=Tb, Dy and Ho) were used as prototypes systems. In the second assumption, the amorphisation is parameterized through the exchange interaction distribution and GdCuAl, in amorphous and crystalline structures, were considered as prototypes systems. Comparisons between the magnetic entropy changes under amorphisation and under the usual magnetic field variation were performed. The model reveals the dependence of refrigerant capacity on the amorphisation parameter, and an optimum amorphisation parameter was calculated. - Highlights: • Theoretical investigation on RAg (R=Tb, Dy and Ho) and GdCuAl amorphous alloys. • Magnetic entropy changes in GdCuAl in both amorphous and crystalline structures. • The refrigerant capacity was compared in both amorphous and crystalline phases.

  8. Interface morphology and mechanical properties of Al-Cu-Al laminated composites fabricated by explosive welding and subsequent rolling process

    Science.gov (United States)

    Hoseini-Athar, M. M.; Tolaminejad, B.

    2016-07-01

    Explosive welding is a well-known solid state method for joining similar and dissimilar materials. In the present study, tri-layered Al-Cu-Al laminated composites with different interface morphologies were fabricated by explosive welding and subsequent rolling. Effects of explosive ratio and rolling thickness reduction on the morphology of interface and mechanical properties were evaluated through optical/scanning electron microscopy, micro-hardness, tensile and tensile-shear tests. Results showed that by increasing the thickness reduction, bonding strength of specimens including straight and wavy interfaces increases. However, bonding strength of the specimens with melted layer interface decreases up to a threshold thickness reduction, then rapidly increases by raising the reduction. Hardness Values of welded specimens were higher than those of original material especially near the interface and a more uniform hardness profile was obtained after rolling process.

  9. Adsorption and subsequent partial photodegradation of methyl violet 2B on Cu/Al layered double hydroxides

    Science.gov (United States)

    Guzmán-Vargas, Ariel; Lima, Enrique; Uriostegui-Ortega, Gisselle A.; Oliver-Tolentino, Miguel A.; Rodríguez, Esaú E.

    2016-02-01

    Uncalcined Cu/Al LDH was studied as adsorbent and photocatalyst in the adsorption and subsequent photodegradation of methyl violet 2B dye (MV2B). Physicochemical characterization was carried out by XRD, FTIR, UV-vis, including photoactive properties, DSC/TGA and SEM. Kinetic and thermodynamic models showed great affinity and sorption capacity, the maximum adsorption capacity was 361.0 mg g-1 obtained by Langmuir model, in addition, the results showed that the dye was adsorbed on the LDH surface. Photocatalytic activity was evaluated in the MV2B dye photodegradation process, and it was confirmed by the presence rad OH radicals monitored by EPR spin trapping technique, additionally, COD and TOC parameters were measured, 13C NMR showed differences for the adsorbed and photodegraded samples.

  10. The activity and selectivity of catalytic peroxide oxidation of chlorophenols over Cu-Al hydrotalcite/clay composite.

    Science.gov (United States)

    Zhou, Shiwei; Gu, Chuantao; Qian, Zhenying; Xu, Jinguang; Xia, Chuanhai

    2011-05-15

    Liquid phase catalytic oxidation of chlorophenols (CPs) was carried out over Cu-Al hydrotalcite/clay composite at ambient temperature and pressure using hydrogen peroxide as oxidant. The results showed that the catalyst had high catalytic activity, with complete oxidation of 4-CP within 40 min at 40 °C. The content and position of chlorine on the aromatic ring had significantly different effects on the oxidation rate of CPs, with the rate sequence of phenol > monochlorophenol (MCP) > dichlorophenol (DCP) > trichlorophenol (TCP), 3-CP > 2-CP > 4-CP, and 3,5-DCP > 3,4-DCP > 2,5-DCP > 2,4-DCP > 2,6-DCP. This was ascribed to the interactions among σ-electron withdrawing conductive effect, π-electron donating conjugative effect, and steric hindrance effect of chlorine. It was evidenced that the catalytic peroxide oxidation of CPs in the first step was selective and rate-limiting, where chlorinated 1,4-benzoquinones formed.

  11. Temperature and grain size effects on the behavior of CuAlBe SMA wires under cyclic loading

    Energy Technology Data Exchange (ETDEWEB)

    Araya, Rodrigo; Marivil, Marco; Mir, Cristobal [Universidad de Chile, Facultad de Ciencias Fisicas y Matematicas, Beaucheff 850, Santiago (Chile); Moroni, Ofelia [Universidad de Chile, Facultad de Ciencias Fisicas y Matematicas, Beaucheff 850, Santiago (Chile)], E-mail: mmoroni@ing.uchile.cl; Sepulveda, Aquiles [Universidad de Chile, Facultad de Ciencias Fisicas y Matematicas, Beaucheff 850, Santiago (Chile)

    2008-11-25

    This study evaluates the properties of a superelastic CuAlBe shape memory alloy under cyclic loading to assess its potential for applications in seismic resistant design. Wires {phi} = 0.5 mm, previously heated during different periods of time, are tested to study the effect of grain size, temperature and strain rate on the strength, equivalent viscous damping, and recentering properties of the alloy. The wires are subjected to quasi-static and dynamic tensile loading tests. The results show that nearly ideal superelastic properties can be obtained up to 3% axial strain. Overall, the damping potential of the alloy is moderate, typically less than 5%. Increased temperatures lead to a reduction in the equivalent damping and an increase in the forward transformation stress, and increased grain sizes lead to an increase in the equivalent damping and a reduction in the forward transformation and ultimate stresses.

  12. Effect of Annealing in Magnetic Field on Ferromagnetic Nanoparticle Formation in Cu-Al-Mn Alloy with Induced Martensite Transformation.

    Science.gov (United States)

    Titenko, Anatoliy; Demchenko, Lesya

    2016-12-01

    The paper considers the influence of aging of high-temperature phase on subsequent martensitic transformation in Cu-Al-Mn alloy. The morphology of behavior of martensitic transformation as a result of alloy aging under annealing in a constant magnetic field with different sample orientation relatively to the field direction and without field was studied for direct control of the processes of martensite induction at cooling. Temperature dependences of electrical resistance, magnetic susceptibility, and magnetization, as well as field dependences of magnetization, and phase composition were found. The tendency to the oriented growth of precipitated ferromagnetic phase nanoparticles in a direction of applied field and to an increase of their volume fraction under thermal magnetic treatment of material that favors a reversibility of induced martensitic transformation is observed.

  13. Thermal and structural alternations in CuAlMnNi shape memory alloy by the effect of different pressure applications

    Science.gov (United States)

    Canbay, Canan Aksu; Polat, Tercan

    2017-09-01

    In this work the effects of the applied pressure on the characteristic transformation temperatures, the high temperature order-disorder phase transitions, the variation in diffraction peaks and the surface morphology of the CuAlMnNi shape memory alloy was investigated. The evolution of the transformation temperatures was studied by differential scanning calorimetry (DSC) with different heating and cooling rates. The differential thermal analysis measurements were performed to obtain the ordered-disordered phase transformations from room temperature to 900 °C. The characteristic transformation temperatures and the thermodynamic parameters were highly sensitive to variations in the applied pressure and also the applied pressure affected the thermodynamic parameters. The activation energy of the sample according to applied pressure values calculated by Kissinger method. The structural changes of the samples were studied by X-ray diffraction (XRD) measurements and by optical microscope observations at room temperature.

  14. Influence of wire-drawing on the properties of a Cu-Al-Be polycrystalline shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mussot-Hoinard, G. [LPMM, UMR CNRS 7554, Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz Cedex (France)], E-mail: genevieve.mussot@univ-metz.fr; Patoor, E. [LPMM, UMR CNRS 7554, Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz Cedex (France); ENSAM, 4, rue Augustin Fresnel, 57078 Metz Cedex 03 (France); Eberhardt, A. [LPMM, UMR CNRS 7554, Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz Cedex (France); ENIM, Ile du Saulcy, 57045 Metz Cedex (France)

    2008-05-25

    In many applications, shape memory or superelastic devices are manufactured from wires. In order to optimize the material behavior and develop new applications, it is necessary to better understand the influence of drawing process parameters on the microstructure obtained at the end of the forming process. We study a polycrystalline Cu-Al-Be shape memory alloy (M{sub s} = -130 deg. C). The initial wire is obtained by hot extrusion (850 deg. C). Its diameter is 1.8 mm. We determine the aptitude of this wire to undergo further diameter reductions according to a process temperature range running from ambient to approximately 600 deg. C. For the given temperature range, a same multi-pass wire-drawing process is defined such as to obtain a desired percent reduction in cross sectional area. Aim of this work is to determine the influence of the process temperature on the microstructure evolution and on the mechanical properties of the wire.

  15. Mg-Cu-Al layered double hydroxides based catalysts for the reduction of nitrates in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Vulić Tatjana J.

    2010-01-01

    Full Text Available The secondary waste and bacterial contamination in physico-chemical and biological separation processes used today for nitrate removal from ground water make novel catalytic technologies that convert nitrates to unharmful gaseous nitrogen, very attractive for scientific research. The Mg-Cu-Al layered double hydroxide (LDH based catalysts with different Mg/Al ratio were investigated in water denitrification reaction in the presence of hydrogen and with solely copper as an active phase. Since LDHs have ion exchange properties and their derived mixed oxides possess memory effect (restoration of layered structure after thermal decomposition, their adsorption capacity for nitrates was also measured in the same model system. All studied samples showed nitrate removal from 23% to 62% following the decrease in Al content, as well as the substantial adsorption capacity ranging from 18% to 38%. These results underlie the necessity to take into account the effects of the adsorption in all future investigations.

  16. Optimization of the processing parameters during internal oxidation of Cu-Al alloy powders using an artificial neural network

    Energy Technology Data Exchange (ETDEWEB)

    Song Kexing; Xing Jiandong; Dong Qiming; Liu Ping; Tian Baohong; Cao Xianjie

    2005-06-15

    Internal oxidation is a commercial method for producing oxide dispersion strengthened copper (ODS Cu). In this paper, the dilute Cu-Al alloy powders containing 0.26 wt% of Al have been internally oxidized at temperatures (T) from 700 to 1000 deg. C, for holding times (t) up to 10 h. The alumina particle size has been observed and determined by electron microscopy using the two-stage preshadowed carbon replica method. By the use of backpropagation network, the non-linear relationship between internal oxidation process parameters (T,t) and alumina particle size has been established on the base of dealing with the experimental data. The results show that the well-trained backpropagation neural network can predict the alumina particle size during internal oxidation precisely and the prediction values have sufficiently mined the basic domain knowledge of internal oxidation process. Therefore, a new way of optimizing process parameters has been provided by the authors.

  17. Structure-Property Relationship of Cu-Al-Ni-Fe Shape Memory Alloys in Different Quenching Media

    Science.gov (United States)

    Saud, Safaa N.; Hamzah, E.; Abubakar, T.; Farahany, S.

    2014-01-01

    This paper presents the effects of heat treatments using various quenching media on the phase transformation parameters and microstructure parameters. The effects of different quenching methods, step-quenched and up-quenched, in various media were evaluated by using differential scanning calorimetry, field emission electron microscopy, energy-dispersive spectrometry, atomic force microscopy, x-ray diffraction, and Vicker's hardness. The variations of the structure and properties of Cu-Al-Ni-Fe shape memory alloys were linked to the variations of morphology, type, and stabilization of the obtained phase. From the DSC results, the use of ice water as a quenching medium produced the highest transformation temperatures, while a brine solution-quenching medium resulted in the highest change of the entropy and enthalpy. Additionally, it was found that the best grain refinement was observed through the use of an oil-quenching medium, due to its high cooling rate.

  18. Dispersion of the linear and nonlinear optical susceptibilities of the CuAl(S{sub 1–x}Se{sub x})₂ mixed chaclcopyrite compounds

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A. H., E-mail: maalidph@yahoo.com [New Technologies - Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Brik, M. G. [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14C, Tartu 50411 (Estonia); Auluck, S. [Council of Scientific and Industrial Research—National Physical Laboratory Dr. K S Krishnan Marg, New Delhi 110012 (India)

    2014-09-14

    Based on the electronic band structure, we have calculated the dispersion of the linear and nonlinear optical susceptibilities for the mixed CuAl(S{sub 1–x}Se{sub x})₂ chaclcopyrite compounds with x=0.0, 0.25, 0.5, 0.75, and 1.0. Calculations are performed within the Perdew-Becke-Ernzerhof general gradient approximation. The investigated compounds possess a direct band gap of about 2.2 eV (CuAlS₂), 1.9 eV (CuAl(S₀.₇₅Se₀.₂₅)₂), 1.7 eV (CuAl(S₀.₅Se₀.₅)₂), 1.5 eV (CuAl(S₀.₂₅Se₀.₇₅)₂), and 1.4 eV (CuAlSe₂) which tuned to make them optically active for the optoelectronics and photovoltaic applications. These results confirm that substituting S by Se causes significant band gaps' reduction. The optical function's dispersion ε₂{sup xx}(ω) and ε₂{sup zz}(ω)/ε₂{sup xx}(ω), ε₂{sup yy}(ω), and ε₂{sup zz}(ω) was calculated and discussed in detail. To demonstrate the effect of substituting S by Se on the complex second-order nonlinear optical susceptibility tensors, we performed detailed calculations for the complex second-order nonlinear optical susceptibility tensors, which show that the neat parents compounds CuAlS₂ and CuAlSe₂ exhibit | χ₁₂₂²}(-2ω;ω;ω) | as the dominant component, while the mixed alloys exhibit | χ₁₁₁²(-2ω;ω;ω) | as the dominant component. The features of | χ₁₂₃²}(-2ω;ω;ω) | and | χ{sub 111}²}(-2ω;ω;ω) | spectra were analyzed on the basis of the absorptive part of the corresponding dielectric function ε₂(ω) as a function of both ω/2 and ω.

  19. Locating Malleable Bulk Metallic Glasses in Zr-Ti-Cu-Al Alloys with Calorimetric Glass Transition Temperature as an Indicator

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    We defined the plastic deformability under constrained loading conditions as malleability for bulk metallic glass (BMG) materials. Quaternary Zr-Ti-Cu-Al alloys in the Zr-rich composition range are selected to investigate the compositional dependence of malleability assessed by bending testing and glass transition temperature (Tg ). As indicated, increasing the Al or Cu concentration in the alloys leads to the rise of T g . The Zr(61)Ti2Cu(25)Al(12) (ZT1) and Zr(61.6)Ti(4.4)Cu(24)Al(10) (ZT3) alloys exhibit an optimal combination of lower T g and higher glass-forming ability. The malleable BMGs such as ZT1 manifests two characters during deformation, the stable propagation of a single shear band indicated by large shear offsets and easy proliferation of shear bands. With increasing the T g of BMG, the yield strength σy,Young's modulus and shear modulus simultaneously increase as well, while the Poisson s ratio decreases. The σy of ZT1 BMG is about 1680 MPa in compression and 1600 MPa in tension. In tensile loading, no any visible plasticity appears even when the strain rate increases up to the order of magnitude of 10(-1)s(-1). In consistent with the T g , malleability of Zr-Ti-Cu-Al BMGs manifests significant compositional dependence. The malleable BMG is associated with lower Tg , as well as lower shear modulus or higher Poisson s ratio, which can be understood on the basis of the correlation of Tg with shear energy barrier in metallic glass. Thus, the calorimetric Tg can be used as an indicator to screen malleable BMG-forming composition, with advantage of experimental accessibility.

  20. Nanostructured antireflective bilayers: Optical design and preparation

    Energy Technology Data Exchange (ETDEWEB)

    Detrich, Ádám [Budapest University of Technology and Economics, Department of Physical Chemistry and Materials Science, Centre for Colloid Chemistry, H-1521 Budapest (Hungary); Nagy, Norbert [Research Centre for Natural Sciences (MTA TTK), Institute for Technical Physics and Materials Science (MFA), P.O. Box 49, H-1525 Budapest (Hungary); Nyári, Mária; Albert, Emőke; Zámbó, Dániel [Budapest University of Technology and Economics, Department of Physical Chemistry and Materials Science, Centre for Colloid Chemistry, H-1521 Budapest (Hungary); Hórvölgyi, Zoltán, E-mail: zhorvolgyi@mail.bme.hu [Budapest University of Technology and Economics, Department of Physical Chemistry and Materials Science, Centre for Colloid Chemistry, H-1521 Budapest (Hungary)

    2014-05-01

    We show different methods for tailoring and fabrication of various cost-effective antireflective nanocoatings on transparent and non-transparent substrates. The main purpose was to prepare coatings with decreased reflectance in the full visible wavelength range using simple wet layer deposition techniques. Structure of coatings was designed by optical simulations applying simplified calculations. The refractive index of substrates was also considered for the calculations. The advantageous optical properties were achieved by bilayered structures combining compact and porous sol–gel derived oxide layers and nanoparticulate films. The bilayered structures enhance the flexibility of design by not only the selection of the layer thicknesses but also by different ways of adjusting the effective refractive index of the layers. Furthermore, chemical stability of the coatings was also investigated. The optical and structural properties of prepared films and bilayered coatings were studied by UV–vis spectroscopy and scanning electron microscopy, respectively. The transmittance of coated glass substrates was above 97.5%, while the reflectance of coated silicon substrates was below 4% between 450 nm and 900 nm. - Highlights: • Designed antireflective bilayered coatings on glass and silicon. • Simple, colloid chemical approaches to preparation. • Favorable optical properties by combining compact and porous oxide layers. • Different ways for adjusting the effective refractive index. • Strong chemical resistance against acidic effects.

  1. STRATURI NANOSTRUCTURATE DE ZnO DOPATE CU Al PENTRU FOTOELECTROZI ÎN STRUCTURILE HIBRIDE PE BAZA FTALOCIANINEI DE CUPRU

    Directory of Open Access Journals (Sweden)

    Tamara POTLOG

    2016-12-01

    Full Text Available În articol este prezentat un studiu al structurii şi proprietăţilor optice ale straturilor subţiri de ZnO dopate cu Al atât netratate termic, cât şi tratate termic în flux de hidrogen la 445oC, precum şi proprietăţile electrice ale structurilor pe baza acestora. Structura acestor straturi a fost făcută utilizând difracţia de radiaţii X, iar proprietăţilor lor optice – prin spectroscopia UV-VIS. S-a constatat că straturile ZnO:Al au structură policristalină de tip wutzite; dimensiunea crista­litelor depinde de regimul tehnologic. Cu creşterea concentraţiei de Al dimensiunea acestora se micşorează, iar tratarea termică în hidrogen conduce la micşorarea valorii Eg indiferent de regimul tehnologic de fabricare a straturilor subţiri. Au fost realizate structuri ZnO/CuPc şi cercetate proprietăţile lor electrice utilizând caracteristicile curent-tensiune şi capacitate-tensiune. Dependenţa capacităţii de tensiune justifică prezenţa regunii de sarcină spaţială.NANOSTRUCTURED ZnO THIN FILMS DOPED WITH Al FOR PHOTOELECTRODS IN THE HYBRID STRUCTURES BASED ON THE COPPER PHTALOCYANINEIn this paper, a study of the structure and optical properties of ZnO thin films doped with Al, both untreated and treated in hydrogen at 445oC, as electrical properties of structures based on them it is presents. Studies on the structure and optical properties were made using X-ray diffraction and UV-VIS spectroscopy. It was found that the ZnO: Al layers were polycrystalline and have a wurtzite structure, crystallite size depends on the technological regime, with increasing concentration of Al their size decreases and annealing in hydrogen leads to decrease in Eg value indifferently of the manufacturing technology. ZnO/CuPc structures were fabricated. Their electrical properties using current-voltage and capacitance-voltage characteristics were investigated. The capacitance-voltage characteristics justify the presence of a space

  2. Structure and magnetic properties of SmCo5/X (X=Fe, Fe-Co, Co) magnetic bilayer films on MgO(110) substrate

    Science.gov (United States)

    Suzuki, Ataru; Hotta, Yusuke; Yamada, Makoto; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi; Inaba, Nobuyuki

    2017-10-01

    Sm17Co83 (at%) films are prepared on bcc-Cr(211), bcc-Fe(211), bcc-Fe65Co35(211), and hcp-Co(1 1 (_) 00) underlayers hetero-epitaxially grown on MgO(110) substrates at 500 °C by using a UHV-MBE system. The growth behavior and the structures are investigated by in-situ reflection high-energy electron diffraction and X-ray diffraction. Sm-Co(1 1 (_) 00) single-crystal films of RT5 ordered structure with the c-axis lying in the film plane grow epitaxially on the underlayers. Small volumes of amorphous phases are interpreted to be involved in the films deposited on these underlayers. The crystal lattice of RT5 magnetic film is slightly deformed from the bulk hexagonal structure, which is caused possibly by the lattice mismatch with the underlayer. The order degree of film deposited on Cr underlayer is higher (S=0.77) than those prepared on Fe, Fe65Co35, and Co underlayers (S: 0.67-0.71). The films show in-plane uniaxial magnetic anisotropies reflecting the magnetocrystalline anisotropy of SmCo5 crystal.

  3. Visible light CrO4(2-) reduction using the new CuAlO2/CdS hetero-system.

    Science.gov (United States)

    Brahimi, R; Bessekhouad, Y; Nasrallah, N; Trari, M

    2012-06-15

    In this study, 64% of hexavalent chromium Cr(VI) reduction from the initial concentration (10(-4) M) is reported under visible light using the (CuAlO(2)/CdS) hetero-system. In this new hetero-system, low doped CuAlO(2) delafossite, synthesized by sol-gel works as an electrons reservoir with a wide space charge region (440 nm). In this case, the electron transfer to chromate is mediated via the hexagonal CdS variety, whose conduction band level is at -1.08 V with respect to the saturated calomel electrode which is more negative than the CrO(4)(2-)/Cr(3+) level. This high reduction rate is achieved under optimized pH and CuAlO(2) percentage. Moreover, salicylic acid gives the best performance among hole scavengers and CuAlO(2) approaches 100% photostability at pH 7.5. The photo-catalytic process follows a pseudo first order kinetic with a half life of 2h. The reaction products are identified by UV-visible spectrophotometry and linear voltametry at a platinum rotating electrode. The results reveal the presence of Cr(3+) after irradiation.

  4. Band gap engineering of CuAl1-x In x S2 alloys for photovoltaic applications: a first principles study

    Science.gov (United States)

    Kumar, S.; Joshi, Suman; Gupta, S. K.; Auluck, S.

    2016-05-01

    The mixed cation alloys CuAl1-x In x S2 span a band gap range that fits the requirement for solar cell light absorbers. However, the materials properties of CuAl1-x In x S2 are not well known as a function of concentration (x). We have used density functional theory calculations to study the structural and electronic properties of these alloys. The most stable configuration out of all possible configurations in the given supercell was obtained with the site occupancy disorder (SOD) program. We find that (i) the structural properties are reproduced to within less than 1% of the measured values; (ii) the CuAl1-x In x S2 alloys are highly miscible with low formation enthalpies; (iii) the band gap of CuAl1-x In x S2 decreases from 3.3 eV to 1.5 eV as In concentration (x) increases from 0 to 1, and shows a small bowing when calculated with hybrid Heyd-Scuseria-Ernzerhof (HSE06) functionals; (iv) the calculated band offset shows that the band gap decreases with the addition of In, resulting mainly from the valence band upshift.

  5. Influence of Isothermal Deformation Parameters on Recrystallization of Columnar Crystal CuAlBe Alloy%等温变形参数对柱状晶CuAlBe合金再结晶的影响

    Institute of Scientific and Technical Information of China (English)

    赵仙兰; 蔡莲淑; 余业球; 黎沃光

    2012-01-01

    The isothermal compression experiment of columnar crystal CuAlBe wires was carried out with a temperature controlled mould on the universal testing machine to study its dynamic recrystallization and precipitation of γ2 phase in the different temperature,deformation and strain rate. Static recrystallization temperature and precipitation of γ2 phase were investigated by reheating the alloy after deformation. The results indicate that the dynamic recrystallization occurs at 550 ℃ when the deformation forms reach more than 20%. Martensite and crack forms below 450 ℃, the dynamic recrystallization doesn't occur at this temperature. Dynamic recrystallization deformation gradually increases with the decrease of the temperature or the increase of the strain rate in the range of 4501 ~550 ℃. Static recrystallization occurs when temperature is 610 ℃. The content of γ2 phase gradually increases with the increase of the deformation temperature before recrystallization. The content of-γ2 phase decreases along with dynamic recrystallization.%在万能材料试验机上采用控温模具对柱状晶CuAlBe合金进行等温压缩变形试验,研究不同变形温度、变形量和变形速率下发生动态再结晶的行为和析出物含量;对变形后的合金重新加热,研究其发生静态再结晶的温度和析出物含量.结果表明:在550℃等温变形,变形量大于20%都发生动态再结晶,450℃以下变形都不发生动态再结晶,但此温度下易形成马氏体和裂纹;在此温度区间,随着变形温度的降低或变形速率的增加,发生动态再结晶所需的变形量逐渐增大.发生静态再结晶的临界温度为610℃,再结晶前的析出物随变形温度的升高而增加,析出物的含量随动态再结晶的进行而降低.

  6. Self-folding graphene-polymer bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Tao [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China); Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Yoon, ChangKyu [Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Jin, Qianru [Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Mingen [Department of Physics, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Liu, Zewen [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China); Gracias, David H., E-mail: dgracias@jhu.edu [Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2015-05-18

    In order to incorporate the extraordinary intrinsic thermal, electrical, mechanical, and optical properties of graphene with three dimensional (3D) flexible substrates, we introduce a solvent-driven self-folding approach using graphene-polymer bilayers. A polymer (SU-8) film was spin coated atop chemically vapor deposited graphene films on wafer substrates and graphene-polymer bilayers were patterned with or without metal electrodes using photolithography, thin film deposition, and etching. After patterning, the bilayers were released from the substrates and they self-folded to form fully integrated, curved, and folded structures. In contrast to planar graphene sensors on rigid substrates, we assembled curved and folded sensors that are flexible and they feature smaller form factors due to their 3D geometry and large surface areas due to their multiple rolled architectures. We believe that this approach could be used to assemble a range of high performance 3D electronic and optical devices of relevance to sensing, diagnostics, wearables, and energy harvesting.

  7. Self-folding graphene-polymer bilayers

    Science.gov (United States)

    Deng, Tao; Yoon, ChangKyu; Jin, Qianru; Li, Mingen; Liu, Zewen; Gracias, David H.

    2015-05-01

    In order to incorporate the extraordinary intrinsic thermal, electrical, mechanical, and optical properties of graphene with three dimensional (3D) flexible substrates, we introduce a solvent-driven self-folding approach using graphene-polymer bilayers. A polymer (SU-8) film was spin coated atop chemically vapor deposited graphene films on wafer substrates and graphene-polymer bilayers were patterned with or without metal electrodes using photolithography, thin film deposition, and etching. After patterning, the bilayers were released from the substrates and they self-folded to form fully integrated, curved, and folded structures. In contrast to planar graphene sensors on rigid substrates, we assembled curved and folded sensors that are flexible and they feature smaller form factors due to their 3D geometry and large surface areas due to their multiple rolled architectures. We believe that this approach could be used to assemble a range of high performance 3D electronic and optical devices of relevance to sensing, diagnostics, wearables, and energy harvesting.

  8. Corrosion behavior of Cu Al Ni shape memory alloy in an oil land field produced fluid; Corrosao da liga com memoria de forma CuAlNi em fluido produzido de campo terrestre de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Ricardo Estefany Aquino [PETROBRAS S.A., Aracaju/Maceio, SE/AL (Brazil). Unidade de Negocios SE-AL; Cruz, Maria Clara Pinto; Figueiredo, Renan T.; Souza, Luciete da Paixao; Araujo, Paulo M.M. [Universidade Tiradentes (UNIT), Aracaju, SE (Brazil)

    2008-07-01

    The corrosion behavior of the CuAlNi shape memory alloy in oil landfield produced groundwater was investigated with polarization curve and mass loss measurements, the latter carried out by immersion in laboratory and field tests. The physico-chemical analysis of five types of oil landfield produced groundwater showed the presence of H{sub 2}S and CO{sub 2}, high salinity, chloride, sulfide and iron ions and relatively neutral pH. The results from electrochemical tests in aerated produced groundwater, in the range of salinity encountered, suggested that the corrosion rate increases at higher saline concentrations. The results from field tests with corrosion test specimens showed a moderate to severe corrosion rate and suggested, in the other hand, that corrosion rates were influenced not only by salinity and oxidizing ions present in the flowing fluid, but also by solid materials in suspension, the fluid's temperature, and the flow velocity. This research is part of a major project which aims to develop couplings for landfield produced fluid transportation pipe connections without welded nor threaded joints. (author)

  9. Oxidative degradation of industrial wastewater using spray deposited TiO2/Au:Fe2O3 bilayered thin films.

    Science.gov (United States)

    Mahadik, M A; Shinde, S S; Pathan, H M; Rajpure, K Y; Bhosale, C H

    2014-12-01

    The Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films are successfully prepared by the spray pyrolysis technique at an optimised substrate temperature of 400 °C and 470 °C, respectively onto amorphous and F:SnO2 coated glass substrates. The effect of TiO2 layer onto photoelectrochemical (PEC), structural, optical and morphological properties of Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films is studied. The PEC characterization shows that, maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 185 μA and Voc = 450 mV) are at 38 nm thickness of TiO2. Deposited films are polycrystalline with a rhombohedral and anatase crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform with seed like grains. The photocatalytic activities of the large surface area (64 cm(2)) TiO2/Au:Fe2O3 thin film photocatalysts were evaluated by photoelectrocatalytic degradation of industrial wastewater under sunlight light irradiation. The results show that the TiO2/Au:Fe2O3 thin film photocatalyst exhibited about 87% and 94% degradation of pollutant in sugarcane and textile industrial wastewater, respectively. The significant reduction in COD and BOD values from 95 mg/L to 13 mg/L and 75 mg/L to 11 mg/L, respectively was also observed.

  10. Light induced diffusion driven self assembly of Ag nanoparticles in a-Se/Ag bi-layer thin film with ultrafast optical response

    Science.gov (United States)

    Bapna, Mukund; Sharma, Rituraj; Barik, A. R.; Khan, Pritam; Ranjan Kumar, Rakesh; Adarsh, K. V.

    2013-05-01

    In this Letter, we demonstrate that femtosecond light-induced interdiffusion of Ag driven by the electrostatic attraction between photo-excited Ag+ ions and negatively charged amorphous layer can act as an efficient single step method for hybrid integration of spatially ordered and interconnected nanoparticles on the surface of amorphous films. Such self assembled complex hybrid structures of silver nanoparticles via bottom-up nano-construction method on a-Se thin film show an ultrafast optical response over an unusually broad wavelength range that can be used to construct optical modulators operating at switching speed of ˜5 ps.

  11. Time-resolved photoresponse of nanometer-thick Nb/NiCu bilayers

    Science.gov (United States)

    Parlato, L.; Pepe, G. P.; Latempa, R.; De Lisio, C.; Altucci, C.; D'Acunto, P.; Peluso, G.; Barone, A.; Taneda, T.; Sobolewski, R.

    2005-07-01

    We present femtosecond optical time-resolved pump-probe investigations of superconducting hybrids structures consisting of Nb/NiCu bilayers with various thickness. Measurements performed on pure Nb and NiCu films are also given. The photoresponse experiments provide the quasiparticle relaxation times in bilayers of different thickness ratios. The study of the photoresponse as a function of the temperature reveals the spatial evolution of the superconductor order parameter across the bilayers.

  12. Multiferroic magnetoelectric coupling effect of bilayer La1.2Sr1.8Mn2O7/PbZr0.3Ti0.7O3 complex thin film

    Science.gov (United States)

    Liang, K.; Zhou, P.; Ma, Z. J.; Qi, Y. J.; Mei, Z. H.; Zhang, T. J.

    2017-05-01

    Magnetoelectric (ME) coupling effect of 2-2-type ferromagnetic/ferroelectric bi-layer multiferroic epitaxial thin film (La1.2Sr1.8Mn2O7/PbZr0.3Ti0.7O3, LSMO/PZT) on SrRuO3 (SRO) substrate is investigated systematically by using Landau-Ginzburg-Devonshire (LGD) thermodynamic theory and modified constitutive equations. The calculating results clarify the detail relationships between ME coupling response and the residual strain, the volume fraction of constituent phases, the interface coupling coefficients, the magnetic field and the temperature. It also shows that improved ME coupling response can be modulated by these parameters. External magnetic fields (H1) induced ME coupling effect could be enhanced around Curie Temperature (Tc) of ferromagnetic phase and ME voltage coefficient (αE31) approaches a maximum at H1 ∼ 4.5 kOe near Tc. The remarkable variations of ME coupling response can be used to provide useful guidelines on the design of multifunctional devices.

  13. EELS study of the inverse martensitic transformation of 2H and 18R Cu-Al-Zn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Magana, F., E-mail: francisco.espinosa@cimav.edu.m [Centro de Investigacion en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Ochoa-Lara, M.T. [Centro de Investigacion en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Lovey, F. [Centro Atomico Bariloche, 8300 S.C. de Bariloche (Argentina); Flores-Zuniga, H. [Universidad Autonoma de Zacatecaa, Av. Lopez Velarde 801, Zacatecas, Zac. 98060 (Mexico); Rios-Jara, D. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, San luis Potosi, S.L.P. 78126 (Mexico)

    2010-01-01

    Changes in 3d states occupancy associated with the inverse martensitic transformation in two samples of Cu-Al-Zn alloys with 2H and 18R martensitic structures were investigated by electron energy loss spectroscopy (EELS). The Cu L{sub 2,3} white-lines intensities, which reflect the unoccupied density of states in 3d bands, were measured in situ, during the phase transformation in both the martensite and austenite phases. We find that the white-lines intensity decreases during the inverse transformation, when going from martensite to austenite. Even though the initial 3d occupation numbers in 2H and 18R martensitic structures are different, after the transformation, the 3d occupation numbers in the now austenitic structure have decreased in both samples, indicating that some electrons left Cu 3d bands during phase transformation. Interestingly enough, the occupation numbers in the final phases, which have the same structure, reach the same value, indicating that changes in EELS spectra are a consequence of structural changes.

  14. Molecular Dynamics Study of Stability of Solid Solutions and Amorphous Phase in the Cu-Al System

    Institute of Scientific and Technical Information of China (English)

    YANG Bin; LAI Wen-Sheng

    2009-01-01

    The relative stability of fcc and bcc solid solutions and amorphous phase with different compositions in the Cu-Al system is studied by molecular dynamics simulations with n-body potentials.For Cu1-xAlx alloys,the calculations show that the fcc solid solution has the lowest energies in the composition region with x<0.32 or x>0.72,while the bcc solid solution has the lowest energies in the central composition range,in agreement with the ball-milling experiments that a single bcc solid solution with 0.30<x< 0.70 is obtained.The evolution of structures in solid solutions and amorphous phase is studied by the coordination number (CN) and bond-length analysis so as to unveil the underlying physics.It is found that the energy sequence among three phases is determined by the competition in energy change originating from the bond length and CNs (or the number of bonds).

  15. A Density Functional Theory Study of Codoping Characteristics of Sulfur with Alkaline Earth in Delafossite CuAlO2

    Science.gov (United States)

    Liu, Qi-Jun; Qin, Han; Liu, Zheng-Tang

    2016-04-01

    The structural, electronic properties and formation energies of sulfur and alkaline earth codoped delafossite CuAlO2 have been investigated using the first-principles density functional theory calculations. Our results reveal that the volume of codoping systems increases with the increasing atomic radius of metal atoms. The formation energies under different growth conditions have been calculated, showing that the codoping systems are formed easily under O-rich growth conditions. Electronic band structures and density of states have been obtained. The decreased bandgaps, enhanced covalence and appearance of electron acceptors after codoping are all good for p-type conductivity. Supported by the National Natural Science Foundation of China under Grant Nos. 11347199, 51402244, and 11547311, the Specialized Research Fund for Doctoral Program of Higher Education of China under Grant No. 20130184120028, the Fundamental Research Fund for the Central Universities, China under Grant Nos. 2682014CX084, 2682014ZT30, and 2682014ZT31, and the fund of the State Key Laboratory of Solidification Processing in NWPU under Grant No. SKLSP201511

  16. Pronounced Plasticity Caused by Phase Separation and β-relaxation Synergistically in Zr-Cu-Al-Mo Bulk Metallic Glasses.

    Science.gov (United States)

    Wang, Tuo; Wang, Lu; Wang, Qinjia; Liu, Yanhui; Hui, Xidong

    2017-04-27

    Bulk metallic glasses (BMGs) are known to have extraordinary merits such as ultrahigh strength and dynamic toughness etc. but tied to the detrimental brittleness, which has become a critical issue to the engineering application and understanding the glass nature. In this article, we report a new class of Zr-Cu-Al-Mo BMGs with extraordinary plastic strain above 20%. "Work-hardening" effect after yielding in a wide range of plastic deformation process has been detected for this kind of BMGs. Compositional heterogeneity, which can be classified into ZrMo- and Cu-rich zones, was differentiated in this kind of BMG. Pronounced humps have been observed on the high frequency kinetic spectrum in Mo containing BMGs, which is the indicator of β-relaxation transition. The underlying mechanism for the excellent plastic deforming ability of this class of BMGs is ascribed to the synergistic effects of soft ZrMo-rich glass formed through phase separation and abundant flow units which related to β-relaxation.

  17. Effects on the martensitic transformations and the microstructure of CuAlNi single crystals after ageing at 473 K

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, V.E.A., E-mail: aaraujo@citedef.gob.ar [Departamento de Investigaciones en Sólidos, CITEDEF, UNIDEF (MINDEF-CONICET), J.B. de La Salle 4397, (1603) Villa Martelli, Buenos Aires (Argentina); Gastien, R. [Departamento de Investigaciones en Sólidos, CITEDEF, UNIDEF (MINDEF-CONICET), J.B. de La Salle 4397, (1603) Villa Martelli, Buenos Aires (Argentina); Zelaya, E. [División Física de Metales, Centro Atómico Bariloche–CNEA, S.C. Bariloche (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Beiroa, J.I.; Corro, I. [Departamento de Investigaciones en Sólidos, CITEDEF, UNIDEF (MINDEF-CONICET), J.B. de La Salle 4397, (1603) Villa Martelli, Buenos Aires (Argentina); Sade, M. [División Física de Metales, Centro Atómico Bariloche–CNEA, S.C. Bariloche (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo (Argentina); Lovey, F.C. [División Física de Metales, Centro Atómico Bariloche–CNEA, S.C. Bariloche (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo (Argentina)

    2015-08-25

    Highlights: • Thermally induced martensitic transformations are studied after ageing at 473 K. • β ↔ β′ stress induced martensitic transformations were analysed after ageing at 473 K. • Pseudoelastic cycling was studied after ageing at 473 K. • Microstructure before and after ageing at 473 K was analysed using TEM. • Effect of γ precipitates and ordering processes is discussed. - Abstract: Isothermal treatments at 473 K were performed in CuAlNi single crystals to study their effects on the main properties of this shape memory material. Both the stress and thermally induced martensitic transformations were monitored after these ageing treatments. An increase of the critical transformation temperature was detected and the type of induced martensite changed from γ′ into β′ after a long enough ageing time. Pseudoelastic cycling was studied after thermal ageing; mechanical behaviour evolved on cycling and a repetitive behaviour was obtained after a small number of cycles. Changes in microstructure were analysed in the β phase by transmission electron microscopy which allowed observing the morphology and distribution of γ precipitates. The changes obtained in shape memory properties were discussed considering the atomic ordering evolution and characteristics of the precipitates.

  18. Surface-Mechanical Properties of Electrodeposited Cu-Al2O3 Composite Coating and Effects of Processing Parameters

    Science.gov (United States)

    Maharana, H. S.; Ashok, Akarapu; Pal, S.; Basu, A.

    2016-01-01

    Cu/Al2O3 composite coatings were prepared from acidic copper sulfate bath containing ultrafine Al2O3 particles by direct current plating method to increase the surface-mechanical property of Cu for its possible use as electrical contact. Effect of ultrafine Al2O3 particle concentration in electrolyte and deposition current density on the surface-mechanical properties of the coatings was investigated. Coatings were characterized by scanning electron microscopy and X-ray diffraction (XRD) techniques for the purpose of surface morphology and phase study. From XRD data, crystallographic texture of the coating was also analyzed. To study the mechanical properties, microhardness testing, adhesion, and wear test were carried out. Improved hardness of the resultant coatings was observed and was correlated with the wt pct of ultrafine particle in the Cu matrix, matrix structure, and crystallographic orientation. Better wear property of the composite coating was also reported from the wear plot and wear track morphology. Altogether, better coating property was attributed toward finer matrix, hard reinforced phase, and preferred orientation in selected conditions. Electrical conductivity of the coating was affected by grain size and second-phase concentration, and the values obtained were in the usable range required for electrical applications.

  19. Correlation between liquid structure and γ2-phase precipitation of Cu-Al-Ni shape memory alloys

    Institute of Scientific and Technical Information of China (English)

    潘学民; 边秀房; 孙景芹; 王伟民

    2002-01-01

    Cu71Al25Ni4 (mole fraction,%) shape memory alloy ribbons exhibit a good shape memory effect, which were prepared by melt-spinning technique. The microstructure of the as-spun ribbons was identified by D/Max-rA X-ray diffractometer. The order degree of martensite increases with decreasing liquid quenching temperature at the same quenching rate. The liquid structure of Cu75Al25 and Cu71Al25Ni4 was investigated using X-ray diffraction method. The distinct pre-peaks have been found in front of main peaks of the structure factors. The pre-peak increases intensity with decreasing temperature or adding Ni. Gaussian peaks decomposing radial distribution function (RDF) indicated that Cu-Al distance is anomalously short. These results suggest that a strong interaction between Cu and Al is favorable to form β-phase-like clusters, which leads to chemical medium-range ordering in melt. This promotes formation of order martensite and suppresses γ2-phase precipitation.

  20. Impact of the volume change on the ageing effects in Cu-Al-Ni martensite: experiment and theory.

    Science.gov (United States)

    Kosogor, Anna; Xue, Dezhen; Zhou, Yumei; Ding, Xiangdong; Otsuka, Kazuhiro; L'vov, Victor A; Sun, Jun; Ren, Xiaobing

    2013-08-21

    The time evolution of the physical properties of martensite during martensite ageing is traditionally explained by the symmetry-conforming short-range order (SC-SRO) principle, which requires the spatial configuration of crystal defects to follow the symmetry change of the host lattice. In the present study, we show that the volume change of the host lattice also contributes to the ageing effects in Cu-Al-Ni shape memory alloy besides the symmetry change. To substantiate this statement the gradual increase of the storage modulus with time at constant temperature was measured by dynamic mechanical analysis (DMA) and the experimental results were quantitatively described in the framework of the symmetry-conforming Landau theory of martensitic transformations in a crystal with defects. The comparison of experimental and theoretical results confirmed that the time dependence of the storage modulus is caused by two different physical mechanisms. Evaluations showing that the first mechanism is driven by the spontaneous symmetry change and the second mechanism is caused by the volume change after the martensitic transformation was carried out.

  1. Capillary wrinkling of thin bilayer polymeric sheets

    Science.gov (United States)

    Chang, Jooyoung; Menon, Narayanan; Russell, Thomas

    We have investigated capillary force induced wrinkling on a floated polymeric bilayer thin sheet. The origin of the wrinkle pattern is compressional hoop stress caused by the capillary force of a water droplet placed on the floated polymeric thin sheet afore investigated. Herein, we study the effect of the differences of surface energy arising from the hydrophobicity of Polystyrene (PS Mw: 97 K, Contact Angle: 88 º) and the hydrophilicity of Poly(methylmethacrylate) (PMMA Mw: 99K, Contact Angle: 68 º) on two sides of a bilayer film. We measure the number and the length of the wrinkles by broadly varying the range of thicknesses of top (9 nm to 550 nm) and bottom layer (25 nm to 330 nm). At the same, there is only a small contrast in mechanical properties of the two layers (PS E = 3.4 GPa, and PMMA E = 3 GPa). The number of the wrinkles is not strongly affected by the composition (PS(Top)/PMMA(Bottom) or PMMA(Top)/PS(Bottom)) and the thickness of each and overall bilayer system. However, the length of the wrinkle is governed by the contact angle of the drop on the top layer of bilayer system. We also compare this to the wrinkle pattern obtained in monolayer systems over a wide range of thickness from PS and PMMA (7 nm to 1 μm). W.M. Keck Foundation.

  2. Anomalous Hall effect in Fe/Gd bilayers

    KAUST Repository

    Xu, W. J.

    2010-04-01

    Non-monotonic dependence of anomalous Hall resistivity on temperature and magnetization, including a sign change, was observed in Fe/Gd bilayers. To understand the intriguing observations, we fabricated the Fe/Gd bilayers and single layers of Fe and Gd simultaneously. The temperature and field dependences of longitudinal resistivity, Hall resistivity and magnetization in these films have also been carefully measured. The analysis of these data reveals that these intriguing features are due to the opposite signs of Hall resistivity/or spin polarization and different Curie temperatures of Fe and Gd single-layer films. Copyright (C) EPLA, 2010

  3. Visible light CrO{sub 4}{sup 2-} reduction using the new CuAlO{sub 2}/CdS hetero-system

    Energy Technology Data Exchange (ETDEWEB)

    Brahimi, R. [Centre of Research in Physical and Chemical Analysis (CRAPC), BP 248, RP 16004 Algiers (Algeria); Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32 16111 Algiers (Algeria); Bessekhouad, Y. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32 16111 Algiers (Algeria); National Veterinary High School, BP 16111 Algiers (Algeria); Nasrallah, N. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32 16111 Algiers (Algeria); Trari, M., E-mail: solarchemistry@gmail.com [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32 16111 Algiers (Algeria)

    2012-06-15

    Graphical abstract: Pseudo-first order kinetic for CrO{sub 4}{sup 2-} photoreduction for various concentrations. Highlights: Black-Right-Pointing-Pointer The work deals with the chromium reduction over CuAlO{sub 2}/CdS hetero-system. Black-Right-Pointing-Pointer The conduction band of CdS (-1.08 V) is more negative than the CrO{sub 4}{sup 2-}/Cr{sup 3+} level. Black-Right-Pointing-Pointer The sensitizer CuAlO{sub 2} has been synthesized by sol-gel. Black-Right-Pointing-Pointer The Cr(VI) reduction follows a pseudo first order kinetic with of salicylic acid. - Abstract: In this study, 64% of hexavalent chromium Cr(VI) reduction from the initial concentration (10{sup -4} M) is reported under visible light using the (CuAlO{sub 2}/CdS) hetero-system. In this new hetero-system, low doped CuAlO{sub 2} delafossite, synthesized by sol-gel works as an electrons reservoir with a wide space charge region (440 nm). In this case, the electron transfer to chromate is mediated via the hexagonal CdS variety, whose conduction band level is at -1.08 V with respect to the saturated calomel electrode which is more negative than the CrO{sub 4}{sup 2-}/Cr{sup 3+} level. This high reduction rate is achieved under optimized pH and CuAlO{sub 2} percentage. Moreover, salicylic acid gives the best performance among hole scavengers and CuAlO{sub 2} approaches 100% photostability at pH 7.5. The photo-catalytic process follows a pseudo first order kinetic with a half life of 2 h. The reaction products are identified by UV-visible spectrophotometry and linear voltametry at a platinum rotating electrode. The results reveal the presence of Cr{sup 3+} after irradiation.

  4. Ion beam mixing isotopic metal bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fell, C.J. [Newcastle Univ., NSW (Australia). Dept. of Physics; Kenny, M.J. [CSIRO, Lindfield, NSW (Australia). Div. of Applied Physics

    1993-12-31

    In order to obtain an insight into the mechanisms of ion-solid interactions, bilayer targets can be prepared from two different isotopes. A mixing study SIMS is to be carried out using specially grown monocrystalline bilayers of {sup 58}Ni / {sup 60}Ni. An important aspect of the work is the preparation of high quality single-crystal thin films. The Ni layers will be grown on the (110) surface of pure Ni and verified for crystallinity using Reflection High-Energy Electron Diffraction and Rutherford Backscattering channelling analysis. The Pd bilayers will be grown on a Pd (100) surface. RHEED will be used to confirm the two-dimensional crystallinity of the surface before and after deposition of each layer, and channelling used to confirm bulk film crystallinity. Single crystal substrates are currently being prepared. Analysis of the Ni (110) surface using RHEED at 9 kV shows a streak spacing which corresponds to a lattice spacing of 2.47 {+-} 0.09 Angstroms. 9 refs., 1 fig.

  5. Improvement in elastic properties of CuAl{sub 0.4}Fe{sub 1.6}O{sub 4} spinel ferrite by rapid thermal cooling

    Energy Technology Data Exchange (ETDEWEB)

    Modi, K. B., E-mail: kunalbmodi2003@yahoo.com; Shah, S. J., E-mail: kunalbmodi2003@yahoo.com; Pathak, T. K., E-mail: kunalbmodi2003@yahoo.com; Vasoya, N. H., E-mail: kunalbmodi2003@yahoo.com; Lakhani, V. K., E-mail: kunalbmodi2003@yahoo.com [Department of Physics, Saurashtra University, Rajkot-360005 (India); Yahya, A. K. [School of Physics and Materials Studies, University Technology MARA, 40450 Shah Alam, Selangor (Malaysia)

    2014-04-24

    The elastic properties of spinel ferrite composition, CuAl{sub 0.4}Fe{sub 1.6}O{sub 4}, quenched from final sintering temperature of 1373 K to liquid nitrogen temperature (∼ 80K) have been studied by means of X-ray powder diffractometry and pulse echo-overlap technique (9 MHz) at 300 K. The magnitude of elastic constants is found to enhance by 15% compared to slowly-cooled counterpart. The observed mechanical strengthening has been discussed in the light of compressive stress on the surface, with tensile stresses at interior regions and corresponding changes in structural parameters. The B{sub o}/G{sub o} ratio indicates the brittle nature of CuAl{sub 0.4}Fe{sub 1.6}O{sub 4}.

  6. Effect of surface structure on the catalytic behavior of Ni:Cu/Al and Ni:Cu:K/Al catalysts for methane decomposition

    Institute of Scientific and Technical Information of China (English)

    S.Tajammul Hussain; Sheraz Gul; Muhammed Mazhar; Dalaver H.Anjum; Faical Larachi

    2008-01-01

    Methane decomposition using nickel, copper, and aluminum (Ni:Cu/Al) and nickel, copper, potassium, and alu-minum (Ni:Cu:K/Al) modified nano catalysts has been investigated for carbon fibers, hydrogen and hydrocarbon production. X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SSIMS), thermal gravimetric analysis (TGA),Fourier transform infrared (FT-IR), secondary electron microscopy/X-ray energy dispersive (SEM-EDX), and temperature pro-grammed desorption (TPD) were used to depict the chemistry of the catalytic results. These techniques revealed the changes in surface morphology and structure of Ni, Cu, Al, and K, and formation of bimetallic and trimetallic surface cationic sites with sifferent cationic species, which resulted in the production of graphitic form of pure carbon on Ni:Cu/Al catalyst. The addition of K has a marked effect on the product selectivity and reactivity of the catalyst system. K addition restricts the formation of carbon on the surface and increases the production of hydrogen and C2, C3 hydrocarbons during the catalytic reaction whereas no hydrocarbons are produced on the sample without K. This study completely maps the modified surface structure and its re-lationship with the catalytic behavior of both systems. The process provides a flexible route for the production of carbon fibers and hydrogen on Ni:Cu/Al catalyst and hydrogen along with hydrocarbons on Ni:Cu:K/Al catalyst. The produced carbon fibers are imaged using a transmission electron microscope (TEM) for diameter size and wall structure determination. Hydrogen produced is COx free, which can be used directly in the fuel cell system. The effect of the addition of Cu and its transformation and interaction with Ni and K is responsible for the production of CO/CO2 free hydrogen, thus producing an environmental friendly clean energy.

  7. Visible light induced H{sub 2}PO{sub 4}{sup -} removal over CuAlO{sub 2} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Benreguia, N. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, (U.S.T.H.B), BP 32, 16111 Algiers (Algeria); Omeiri, S. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, (U.S.T.H.B), BP 32, 16111 Algiers (Algeria); Centre of Research in Physical and Chemical analysis (CRAPC), BP 248 Algiers RP 16004, Algiers (Algeria); Bellal, B. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, (U.S.T.H.B), BP 32, 16111 Algiers (Algeria); Trari, M., E-mail: solarchemistry@gmail.com [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, (U.S.T.H.B), BP 32, 16111 Algiers (Algeria)

    2011-09-15

    Highlights: {yields} The photoactivity of the delafossite CuAlO{sub 2} is enhanced under mild conditions. {yields} The conduction band of CuAlO{sub 2} is of cationic type, providing a high reducing power. {yields} The photo reduction of phosphate is well described by a first order kinetic. - Abstract: The delafossite CuAlO{sub 2} is successfully used for the visible light driven H{sub 2}PO{sub 4}{sup -} reduction. It is prepared from the nitrates decomposition in order to increase the ratio of reaction surface per given mass. CuAlO{sub 2} is a narrow band gap semiconductor which exhibits a good chemical stability with a corrosion rate of 1.70 {mu}mol year{sup -1} at neutral pH. The flat band potential (+0.25 V{sub SCE}) is determined from the Mott-Schottky characteristic. Hence, the conduction band, positioned at (-1.19 V{sub SCE}), lies below the H{sub 2}PO{sub 4}{sup -} level yielding a spontaneous reduction under visible illumination. The photocatalytic process is investigated under mild conditions and 30% conversion occurs in less than {approx}6 h with a quantum efficiency of {approx}0.04% under full light. The concentration decreases by a factor of 39% after a second cycle. The photoactivity follows a first order kinetic with a rate constant of 6.6 x 10{sup -2} h{sup -1}. The possibility of identifying the reaction products via the intensity-potential characteristics is explored. The decrease of the conversion rate over illumination time is due to the competitive water reduction.

  8. Fabrication of low adhesive superhydrophobic surfaces using nano Cu/Al{sub 2}O{sub 3} Ni–Cr composited electro-brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Tianchi [College of Mechanical & Electrical Engineering, Xu Zhou 221116 (China); Ge, Shirong [College of Mechanical & Electrical Engineering, Xu Zhou 221116 (China); College of Materials Science and Engineering, China University of Mining and Technology, Xu Zhou 221116 (China); Liu, Hongtao, E-mail: liuht100@126.com [College of Materials Science and Engineering, China University of Mining and Technology, Xu Zhou 221116 (China); Sun, Qinghe; Zhu, Wei; Yan, Wei; Qi, Jianwei [College of Materials Science and Engineering, China University of Mining and Technology, Xu Zhou 221116 (China)

    2015-11-30

    Highlights: • We fabricate a low adhesive superhydrophobic nano Cu/Al{sub 2}O{sub 3} composited Ni–Cr coating via brush plating. • We investigate the influence of process parameters on hydrophobic properties process. • We discuss the formation mechanism of structures on the surface and using water rebound height to explain the low adhesive force mechanism. - Abstract: Superhydrophobic nano Cu/Al{sub 2}O{sub 3} Ni–Cr composited coating with a low adhesive force was deposited onto the Q345 carbon steel via electro-brush plating. Surface morphologies of nano Cu/Al{sub 2}O{sub 3} Ni–Cr composited coating were investigated by scanning electron microscope (SEM). Chemical compositions were characterized by energy dispersive spectroscopy (EDS). First of all, by adjusting different process parameters such as working voltage, relative velocity, Cu particles concentration and plating time, we obtain the most optimal parameters: working voltage is 15 V, relative velocity is 4.8 m/min, Cu particles concentration is 5 g/L and plating time is 60 s. Under the best process parameters, the water contact angle reaches to 156° and a sliding angle is less than 2° on the nano Cu/Al{sub 2}O{sub 3} Ni–Cr coating. Then the mechanism of the superhydrophobic and low adhesion characteristic of this surface were explained by Cassie's model. Low adhesive force can be characterized by max rebound height of water droplet. As a result, to achieve low adhesive surface it is necessary to decrease the fraction of the solid/liquid interface under the water droplet. Finally the coating was proved to have an excellent self-cleaning performance.

  9. Elaboración de aleaciones de Cu-Al-Ni con efecto memoria de forma mediante pulvimetalurgia

    Directory of Open Access Journals (Sweden)

    Pérez-Sáez, R. B.

    1998-05-01

    Full Text Available During the production of shape memory alloys, a very fine grain size should be obtained in order to obtain better mechanical properties and a good thermomechanical behaviour during cycling. The classically used grain refiners show some secondary effects on the martensitic transformations that could be at the origin of some technological problems. For this reason, a new processing method by powder metallurgy has been developed for this kind of alloys. The three proceeding stages are described: Atomization, hot isostatic pressing and hot rolling. The microstructure of the materials is characterized. The martensitic transformation and the thermomechanical properties are also studied.

    En la elaboración de aleaciones Cu-Al-Ni con efecto memoria de forma es importante conseguir un tamaño de grano fino, para mejorar las propiedades mecánicas y el comportamiento durante el ciclado termomecánico. Clásicamente, esto se ha conseguido mediante la adición de refinadores de grano; sin embargo, los efectos secundarios que éstos producen pueden ser problemáticos. Por esta razón, se ha desarrollado un nuevo método de procesado de este tipo de aleaciones mediante pulvimetalurgia. En este trabajo se presenta el proceso de elaboración consistente en tres etapas: atomización, compactación isostática en caliente y laminación en caliente. Se estudia la microestructura del material, se caracteriza la transformación martensítica y se determinan las propiedades termomecánicas.

  10. Photocatalytic reduction of Cr(VI) on the new hetero-system CuAl2O4/TiO2.

    Science.gov (United States)

    Gherbi, R; Nasrallah, N; Amrane, A; Maachi, R; Trari, M

    2011-02-28

    Visible light driven HCrO(4)(-) reduction was successfully achieved over the new hetero-system CuAl(2)O(4)/TiO(2). The spinel, elaborated by nitrate route, was characterized photo electrochemically. The optical gap was found to be 1.70 eV and the transition is directly allowed. The conduction band (-1.05 V(SCE)) is located below that of TiO(2), more negative than the HCrO(4)(-)/Cr(3+) level (+0.58 V(SCE)) yielding a thermodynamically feasible chromate reduction upon visible illumination. CuAl(2)O(4) is stable against photo corrosion by holes consumption reaction involving salicylic acid which favors the charges separation. There is a direct correlation between the dark adsorption and the photo activity. A reduction of more than 95% of chromate was achieved after 3 h irradiation at pH 2 with an optimal mass ratio (CuAl(2)O(4)/TiO(2)) equal to 1/3. The reduction follows a first order kinetic with a half life of ∼1 h and a quantum yield of 0.11% under polychromatic light. Prolonged illumination was accompanied by a deceleration of the Cr(VI) reduction thanks to the competitive water discharge. The hydrogen evolution, an issue of energetic concern, took place with a rate of 3.75 cm(3) (g catalyst)(-1) h(-1).

  11. The effects of substituting B for Cu on the magnetic and shape memory properties of CuAlMnB alloys

    Energy Technology Data Exchange (ETDEWEB)

    Aydogdu, Y.; Aydogdu, A. [Gazi University, Department of Physics, Faculty of Science, Ankara (Turkey); Turabi, A.S.; Vance, E.D.; Karaca, H.E. [University of Kentucky, Department of Mechanical Engineering, Lexington, KY (United States); Kok, M. [Firat University, Department of Physics, Faculty of Science, Elazig (Turkey); Kirat, G. [Inonu University, Graduate School of Natural and Applied Sciences, Malatya (Turkey)

    2016-07-15

    The effects of B addition on the magnetization, mechanical and shape memory properties in Cu{sub 70-x}Al{sub 24}Mn{sub 6}B{sub x} at.% (x = 0, 1, 2, 3, 4) alloys have been investigated. The ductility was decreased, while the strength was improved with B addition. Transformation temperatures were increased with B content due to increased e/a ratio. Martensite start temperature of B-free CuAlMn was found to be 37.3 C and increased to 218.8 C with 4 % B addition. B-free CuAlMn exhibited shape memory effect with a recoverable strain of 2.25 % under 200 MPa and a perfect superelasticity with a recoverable strain of 2.5 % at 163 C. B addition degraded the shape memory properties and eventually resulted in the lack of recoverable strain. In addition, saturation magnetization was increased with B content. Moreover, the addition of B slightly decreased the ductility of the alloy. It was found that the magnetization, mechanical and shape memory properties CuAlMn alloys can be tailored by quaternary alloying with B. (orig.)

  12. Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

    Science.gov (United States)

    Ahmed, Nesreen S.; Menzel, Robert; Wang, Yifan; Garcia-Gallastegui, Ainara; Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N.; Mokhtar, Mohamed

    2017-02-01

    Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

  13. First-principle Calculations of Mechanical Properties of Al2Cu, Al2CuMg and MgZn2 Intermetallics in High Strength Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    LIAO Fei

    2016-12-01

    Full Text Available Structural stabilities, mechanical properties and electronic structures of Al2Cu, Al2CuMg and MgZn2 intermetallics in Al-Zn-Mg-Cu aluminum alloys were determined from the first-principle calculations by VASP based on the density functional theory. The results show that the cohesive energy (Ecoh decreases in the order MgZn2 > Al2CuMg > Al2Cu, whereas the formation enthalpy (ΔH decreases in the order MgZn2 > Al2Cu > Al2CuMg. Al2Cu can act as a strengthening phase for its ductile and high Young's modulus. The Al2CuMg phase exhibits elastic anisotropy and may act as a crack initiation point. MgZn2 has good plasticity and low melting point, which is the main strengthening phase in the Al-Zn-Mg-Cu aluminum alloys. Metallic bonding mode coexists with a fractional ionic interaction in Al2Cu, Al2CuMg and MgZn2, and that improves the structural stability. In order to improve the alloys' performance further, the generation of MgZn2 phase should be promoted by increasing Zn content while Mg and Cu contents are decreased properly.

  14. A simple method to tune graphene growth between monolayer and bilayer

    Directory of Open Access Journals (Sweden)

    Xiaozhi Xu

    2016-02-01

    Full Text Available Selective growth of either monolayer or bilayer graphene is of great importance. We developed a method to readily tune large area graphene growth from complete monolayer to complete bilayer. In an ambient pressure chemical vapor deposition process, we used the sample temperature at which to start the H2 flow as the control parameter and realized the change from monolayer to bilayer growth of graphene on Cu foil. When the H2 starting temperature was above 700°C, continuous monolayer graphene films were obtained. When the H2 starting temperature was below 350°C, continuous bilayer films were obtained. Detailed characterization of the samples treated under various conditions revealed that heating without the H2 flow caused Cu oxidation. The more the Cu substrate oxidized, the less graphene bilayer could form.

  15. The Mechanical Aspects of Formation and Application of PDMS Bilayers Rolled into a Cylindrical Structure

    Directory of Open Access Journals (Sweden)

    Dongwon Kang

    2015-01-01

    Full Text Available A polydimethylsiloxane (PDMS film with its surface being oxidized by a plasma treatment or a UV-ozone (UVO treatment, that is, a bilayer made of PDMS and its oxidized surface layer, is known to roll into a cylindrical structure upon exposure to the chloroform vapor due to the mismatch in the swelling ratio between PDMS and the oxidized layer by the chloroform vapor. Here we analyzed the formation of the rolled bilayer with the mechanical aspects: how the mismatch in the swelling ratio of the bilayer induces rolling of the bilayer, why any form of trigger that breaks the symmetry in the in-plane stress level is needed to roll the bilayer uniaxially, why the rolled bilayer does not unroll in the dry state when there is no more mismatch in the swelling ratio, and how the measured curvature of rolled bilayer matches well with the prediction by the theory. Moreover, for the use of the rolled bilayer as the channel of the microfluidic device, we examined whether the rolled bilayer deforms or unrolls by the flow of the aqueous solution that exerts the circumferential stress on the rolled bilayer.

  16. 内氧化法制备Cu-Al2O3薄板复合材料及其重熔后的组织性能%Cu-Al2O3 composite sheets prepared by internal oxidation and its microstructure and properties after re-melting

    Institute of Scientific and Technical Information of China (English)

    李新; 田保红; 任凤章; 熊毅; 魏世忠; 马景灵

    2016-01-01

    Cu-Al2O3 composite sheets were prepared by internal oxidation used Cu-Al alloy sheets with different Al content (0.2%,0.35% and 0.5%,mass) as raw materials.Microstructure and properties of the Cu-Al2O3 composite sheets under the same oxidation temperature and time were studied.Meanwhile,the Cu-Al2O3 bulk composites were tried to prepare by re-melting method used the Cu-Al2O3 composites sheets with dispersive distribution of Al2O3 particles.The results show that the external grains in the internal oxidation layer of the Cu-Al2O3 composite sheets are smaller than that of internal grains.With the increasing Al content,under the same oxidation time,the internal oxidation layer depth becomes smaller and the internal grains become coarser.A large amount of the γ-Al2O3 phase is distributed in the Cu matrix of the composites prepared by internal oxidation.The size of the γ-Al2O3 particles is 10-30 nm and the particle spacing is 20-70 nm.The γ-Al2O3 phase strengthens the Cu matrix,so the hardness of the composites surface is significantly increased compared with the alloy,and the hardness gradually decreases from the surface to the inside.Al2O3 particles in the Cu-Al2O3 sheets aggregate and grow after re-melting.Thus,re-melting of composite sheets to prepare the Cu-Al2O3 bulk composites is unfeasible.%采用不同Al含量(0.20%、0.35%和0.50%,质量分数)的Cu-Al合金薄板内氧化法制备Cu-Al2O3薄板复合材料.对比分析了相同内氧化温度和时间下,不同Al含量的Cu-Al合金薄板内氧化制备出的Cu-Al2O3薄板复合材料的组织性能.并尝试采用Cu-Al2O3薄板复合材料重熔法制备Al2O3颗粒弥散分布的Cu-Al2O3块体复合材料.结果表明,Cu-Al2O3薄板复合材料内氧化层外部晶粒比内部晶粒细小;随着Al质量分数的增加,在相同的内氧化时间下,内氧化层的深度逐渐减小,内氧化层的内部晶粒逐渐粗化;内氧化后所得复合材料的Cu基体中弥散分布着大量的γ-Al2

  17. Pattern Formation in Dewetting Nanoparticle/Polymer Bilayers

    Science.gov (United States)

    Esker, Alan; Paul, Rituparna; Karabiyik, Ufuk; Swift, Michael; Hottle, John

    2008-03-01

    Comprised of inorganic cores and flexible organic coronae with 1 -- 2 nm diameter monodisperse sizes, polyhedral oligomeric silsesquioxanes (POSS) are ideal model nanofillers. Our discovery that one POSS derivative, trisilanolphenyl-POSS (TPP), can form Langmuir-Blodgett (LB) films on hydrophobic substrates, allows us to create thin film bilayers of precisely controlled thickness and architecture. Work with poly(t-butylacrylate) (PtBA)/TPP bilayers reveals a two-step dewetting mechanism in which the upper TPP layer dewets first, followed by the formation of isolated holes with intricate, fractal, nanofiller aggregates. Like the PtBA/TPP bilayers, polystyrene (PS)/TPP bilayers also undergo a two-step dewetting mechanism. However, the upper TPP layer initially forms cracks that may arise from mismatches in thermal expansion coefficients. These cracks then serve as nucleation sites for complete dewetting of the entire bilayer. Understanding the rich diversity of surface patterns that can be formed from relatively simple processes is a key feature of this work.

  18. Enhanced thermoelectric properties in p-type Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} alloy by combining incorporation and doping using multi-scale CuAlO{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Song, Zijun; Liu, Yuan; Zhou, Zhenxing; Lu, Xiaofang; Wang, Lianjun [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai (China); Institute of Functional Materials, Donghua University, Shanghai (China); Zhang, Qihao [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China); University of Chinese Academy of Sciences, Beijing (China); Jiang, Wan [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai (China); Institute of Functional Materials, Donghua University, Shanghai (China); School of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen (China); Chen, Lidong [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China)

    2017-01-15

    Multi-scale CuAlO{sub 2} particles are introduced into the Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} matrix to synergistically optimize the electrical conductivity, Seebeck coefficient, and the lattice thermal conductivity. Cu element originating from fine CuAlO{sub 2} grains diffuses into the Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} matrix and tunes the carrier concentration while the coarse CuAlO{sub 2} particles survive as the second phase within the matrix. The power factor is improved at the whole temperatures range due to the low-energy electron filtering effect on Seebeck coefficient and enhanced electrical transport property by mild Cu doping. Meanwhile, the remaining CuAlO{sub 2} inclusions give rise to more boundaries and newly built interfaces scattering of heat-carrying phonons, resulting in the reduced lattice thermal conductivity. Consequently, the maximum ZT is found to be enhanced by 150% arising from the multi-scale microstructure regulation when the CuAlO{sub 2} content reaches 0.6 vol.%. Not only that, but the ZT curves get flat in the whole temperature range after introducing the multi-scale CuAlO{sub 2} particles, which leads to a remarkable increase in the average ZT. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Cu/Al管气体火焰钎焊接头特征及热力学分析%Characteristics and thermodynamics analysis of oxyacetylene flame brazing joint of Cu/Al tubes

    Institute of Scientific and Technical Information of China (English)

    罗键; 赵国际; 王向杰; 孙玉

    2011-01-01

    Entropy changes in chemical reaction of Cu/Al intermetallic compounds formation in Cu/Al oxyacetylene flame brazing are calculated, and the tendency of Cu/Al intermetallic compounds form and transform to CuAl2 is analyzed with the method of chemical thermodynamics. The microstructure and characteristics of elements distribution and diffusion of the Cu/Al oxyacetylene flame brazing joint are analyzed by XRD, SEM and EDS. Results show that, under the condition of Cu/Al oxyacetylene flame brazing, the CuAl2 intermetallic compounds formed by the direct reaction of Cu&Al atoms and the sustained reaction of Cu/Al intermetallic compounds with Al atoms. CuAl has relatively strong independent transformation trend. The results of thermodynamics analysis and calculation are consistent with the XRD of joint. Brazing joint can be divided into three feature regions: the a-Al and binary eutectic (α-Al+CuAl2) region is near Al side with the width of about 30 μm; the fine multiple eutectic structure is formed in brazing seam center near Al side with the width of about 150 μm; and the region near Cu substrate with the width of about 120 μm, where Cu diffuses largely and reacts richly with Al and massive CuAl2 is formed like corals.%通过计算Cu/Al管氧乙炔气体火焰钎焊条件下形成金属间化合物的各化学反应的熵变,对Cu/Al金属间化合物的形成及向CuAl2转化的趋势进行了化学热力学分析;结合XRD、SEM、EDS研究了Cu/Al管氧乙炔气体火焰钎焊接头组织与元素分布特征.结果表明,Cu/Al管氧乙炔气体火焰钎焊条件下,接头中脆性金属间化合物CuAl2由Cu、Al原子的直接结合和其他Cu/Al金属间化合物与Al原子的继续反应生成,其中CuAl自主转化趋势较强;热力学计算分析与接头XRD分析结果一致.钎焊接头可分为3个特征区域:靠近Al基体侧形成了宽度约30μm的α-Al与α-Al+CuAl2二元共晶区;钎缝中心偏Al基体一侧形成了宽度约150

  20. Photocatalytic reduction of Cr(VI) on the new hetero-system CuAl{sub 2}O{sub 4}/TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gherbi, R. [Laboratory of Reaction Engineering, Faculty of Mechanic and Engineering Processes, USTHB, BP 32, 16111 Algiers (Algeria); Nasrallah, N. [Laboratory of Reaction Engineering, Faculty of Mechanic and Engineering Processes, USTHB, BP 32, 16111 Algiers (Algeria); Equipe chimie et Ingenierie des procedes, UMR CNRS 6226, E.N.S.C.R., Avenue du General Leclerc, CS 50837, 35708 Rennes Cedex 7 (France); Amrane, A. [Equipe chimie et Ingenierie des procedes, UMR CNRS 6226, E.N.S.C.R., Avenue du General Leclerc, CS 50837, 35708 Rennes Cedex 7 (France); Maachi, R. [Laboratory of Reaction Engineering, Faculty of Mechanic and Engineering Processes, USTHB, BP 32, 16111 Algiers (Algeria); Trari, M., E-mail: solarchemistry@gmail.com [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, USTHB, BP 32, 16111 Algiers (Algeria)

    2011-02-28

    Visible light driven HCrO{sub 4}{sup -} reduction was successfully achieved over the new hetero-system CuAl{sub 2}O{sub 4}/TiO{sub 2}. The spinel, elaborated by nitrate route, was characterized photo electrochemically. The optical gap was found to be 1.70 eV and the transition is directly allowed. The conduction band (-1.05 V{sub SCE}) is located below that of TiO{sub 2}, more negative than the HCrO{sub 4}{sup -}/Cr{sup 3+} level (+0.58 V{sub SCE}) yielding a thermodynamically feasible chromate reduction upon visible illumination. CuAl{sub 2}O{sub 4} is stable against photo corrosion by holes consumption reaction involving salicylic acid which favors the charges separation. There is a direct correlation between the dark adsorption and the photo activity. A reduction of more than 95% of chromate was achieved after 3 h irradiation at pH 2 with an optimal mass ratio (CuAl{sub 2}O{sub 4}/TiO{sub 2}) equal to 1/3. The reduction follows a first order kinetic with a half life of {approx}1 h and a quantum yield of 0.11% under polychromatic light. Prolonged illumination was accompanied by a deceleration of the Cr(VI) reduction thanks to the competitive water discharge. The hydrogen evolution, an issue of energetic concern, took place with a rate of 3.75 cm{sup 3} (g catalyst){sup -1} h{sup -1}.

  1. Study on Sn-Zn Solder Used in Cu-Al Soldering%用于铜铝焊接的锡锌焊料研究

    Institute of Scientific and Technical Information of China (English)

    倪广春; 张浩; 韩敏

    2013-01-01

    Lead-free electronic products led the development of lead-free solder technology. Taking cost factors into account, some copper material has been replaced by aluminum material. When ordinary Sn-Cu and Sn-Ag-Cu solder are used in soldering of Cu-Al, there is the electrochemical corrosion problems. So Sn-Zn solder is used for Cu-Al soldering. However, the joints of Sn-Zn solder are brittle and easy to crack. Focus on problems in Cu-Al soldering joint of electrical and electronic devices, put forward Sn-Zn-X alloy soldering materials, did a large number of experiments, and achieved good results.%电子产品无铅化的推广带动了无铅焊料技术的发展,考虑到成本因素,部分铜材已被铝材取代。普通的锡铜系和锡银铜系焊料在铜铝焊接时,存在电化学腐蚀问题,因此多用锡锌焊料进行焊接。但锡锌焊料的焊点脆,存在易开裂的问题。针对电工电子器件铜铝焊接点存在的问题,提出了Sn一Zn一X多元合金焊接材料,并做了大量实验,取得很好的效果。

  2. A Detailed Observation on Successive Stress-Induced Martensite Transformation in CuAlMnZnZr Alloy Polycrystalline Above Af

    Institute of Scientific and Technical Information of China (English)

    Li Zhou; Wang Ming-pu; Tang Wang; Guo Ming-xing

    2004-01-01

    The successive stress-induced martensite morphologies and mechanisms in polycrystalline CuAlMnZnZr samples have been examined. By applying stress to the uniform β1 matrix, two or more orientation plates of M18R martensite are stress-induced in a grain. With further increasing stress, one orientation plate depletes the other and coalesces into a single region in some view field. The mechanisms by which these are developed have been ascertained, and include variant-variant coalescence, stress-induced martensite to martensite transformation and the complicated cross-like stress-induced martensite formation.

  3. Preparation and physical properties of CuAl 1- xMn xO 2 (0 ≤ x ≤ 0.2) delafossites

    Science.gov (United States)

    Töpfer, Jörg; Trari, Mohamed; Doumerc, Jean-Pierre

    2007-03-01

    The formation of a CuAl 1- xMn xO 2 solid solution for a limited range of x values (0 ≤ x ≤ 0.2) is demonstrated. The samples were synthesized by solid state reactions in silica sealed tubes. They crystallize with the 3R delafossite structure (space group R3¯m). Magnetic studies show that Mn 3+ ions are in the HS state and that the predominant interactions are antiferromagnetic. The oxides are semiconductors with an activation energy decreasing with x.

  4. Effects of aging on the structure and damping behaviors of a novel porous CuAlMn shape memory alloy fabricated by sintering–dissolution method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Q.Z., E-mail: qzwang@hebut.edu.cn; Lu, D.M.; Cui, C.X., E-mail: hutcui@hebut.edu.cn; Liu, W.J.; Xu, M.; Yang, J.

    2014-10-06

    Effects of aging on the microstructures and damping behaviors of a porous CuAlMn shape memory alloy were studied. It is found that after aging at 350 °C both the damping capacity of the alloy in the martensite state and the height of the internal friction peak arising from the reverse martensitic transformation increase due to the refining of martensitic structure and the annihilation of quenched-in vacancies. It is also found that the atomic ordering and the annihilation of quenched-in vacancies can promote the reverse martensitic transformation to take place, resulting in a significantly decreased temperature of the internal friction peak.

  5. Catalytic wet oxidation of dyehouse effluents with Cu/Al{sub 2}O{sub 3} and Al-Cu pillared clays

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.K.; Kim, S.C.; Kim, D.S.; Lee, G.S.; Yoon, S.B. [Dept. of Chemical Engineering/Environmental Protection, Environment and Regional Development Inst., Gyeongsang National Univ., Gyeongnam (Korea)

    2003-07-01

    Catalytic wet oxidation of real dyehouse effluents was performed in a batch reactor and a continuous flow pilot plant scale reactor by using Cu/Al{sub 2}O{sub 3} and Al-Cu-PILC catalysts. Hydrogen peroxide was used as the oxidant. The removal of TOC and color was strongly related to the consumption of H{sub 2}O{sub 2} and the subsequent formation of HO-. Copper components in the catalysts, especially in the Al-Cu-PILCs, showed successful activity toward complete removal of TOC and color. In addition the Al-Cu-PILC catalysts were extremely stable against copper leaching. (orig.)

  6. Characterization of Deformation Behavior of Individual Grains in Polycrystalline Cu-Al-Mn Superelastic Alloy Using White X-ray Microbeam Diffraction

    Directory of Open Access Journals (Sweden)

    Eui Pyo Kwon

    2015-10-01

    Full Text Available White X-ray microbeam diffraction was applied to investigate the microscopic deformation behavior of individual grains in a Cu-Al-Mn superelastic alloy. Strain/stresses were measured in situ at different positions in several grains having different orientations during a tensile test. The results indicated inhomogeneous stress distribution, both at the granular and intragranular scale. Strain/stress evolution showed reversible phenomena during the superelastic behavior of the tensile sample, probably because of the reversible martensitic transformation. However, strain recovery of the sample was incomplete due to the residual martensite, which results in the formation of local compressive residual stresses at grain boundary regions.

  7. Effects of reaction conditions on hydrogen production and carbon nanofiber properties generated by methane decomposition in a fixed bed reactor using a NiCuAl catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Suelves, I.; Pinilla, J.L.; Lazaro, M.J.; Moliner, R. [Instituto de Carboquimica CSIC, Miguel Luesma Castan, 4, 50015 Zaragoza (Spain); Palacios, J.M. [Instituto de Catalisis y Petroleoquimica, CSIC, Cantoblanco, Marie Curie 2, 28049 Madrid (Spain)

    2009-07-01

    In this paper, the results obtained in the catalytic decomposition of methane in a fixed bed reactor using a NiCuAl catalyst prepared by the fusion method are presented. The influences of reaction temperature and space velocity on hydrogen concentration in the outlet gases, as well as on the properties of the carbon produced, have been investigated. Reaction temperature and the space velocity both increase the reaction rate of methane decomposition, but also cause an increase in the rate of catalyst deactivation. Under the operating conditions used, the carbon product is mainly deposited as nanofibers with textural properties highly correlated with the degree of crystallinity. (author)

  8. Structural transformation in nano-structured CuAl{sub x}Cr{sub x}Fe{sub 2-2x}O{sub 4} system

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, D. K., E-mail: daxabjoshi@gmail.com [Government Science College, Ahmedabad, Gujarat (India); Chhantbar, M. C. [Shakersinh Vaghela Bapu Institute of Technology, PO-Vasan, Dist-Gandhiangar. India (India); Joshi, H. H. [Department of Physic, Saurashtra University, Rajkot, Gujarat (India)

    2015-06-24

    Polycrystalline spinel ferrite system CuAl{sub x}Cr{sub x}Fe{sub 2-2x}O{sub 4} (x=0.2, 0.6) was synthesized by solid-state reaction route. Nanoparticles of the samples have been prepared by using high energy ball milling technique with different milling durations and characterized by X-ray Diffraction and Tunneling Electron Microscope. It is observed that the structural transformation occurred from Cubic to tetragonal and particle size varied between 29 nm -14 nm with increase of milling time.

  9. Formation of "solvent-free" black lipid bilayer membranes from glyceryl monooleate dispersed in squalene.

    Science.gov (United States)

    White, S H

    1978-09-01

    A simple technique for forming "black" lipid bilayer membranes containing negligible amounts of alkyl solvent is described. The membranes are formed by the method of Mueller et al (Circulation. 1962. 26:1167.) from glyceryl monooleate (GMO) dispersed in squalene. The squalene forms an annulus to satisfy the boundary conditions of the planar bilayer but does not appear to dissolve noticeably in the bilayer itself. The specific geometric capacitance (Cg) of the membranes at 20 degrees C formed by this technique is 0.7771 +/- 0.0048 muF/cm2. Theoretical estimates of Cg for solvent-free bilayers range from 0.75 to 0.81 muF/cm2. Alkane-free GMO bilayers formed from n-octadecane by the solvent freeze-out method of White (Biochim. Biophys. Acta. 1974. 356:8) have values of Cg = 0.7903 +/- 0.0013 muF/cm2 at 20.5 degrees C. The agreement between the various values of Cg strongly suggests that the bilayers are free of squalene. DC potentials applied to the bilayers have no detectable effect on the value of Cg, as expected for solvent-free films. The ability to form bilayers essentially free of the solvent used in the forming solution makes it possible to determine the area per molecule of the surface active lipid in the bilayer. The area per molecule of GMO at 20 degrees C is estimated to be 37.9 +/- 0.2 A2.

  10. Étude par spectroscopie d'admittance et MEB de la dégradation électrique des couches minces de CuAlS{2} non dopé déposées sous vide

    Science.gov (United States)

    Helali, N.; Bouricha, B.; Rezig, B.

    1998-07-01

    We have accelerated the ageing of CuAlS2 by the application of a static electrical field for different degradation times. We have investigated the admittance spectroscopy and the scanning electron microscopy to follow and understand the (mass-charge) coupled transport processes produced in the volume and on the surface of these films. The electrical constraint induces, after an incubation phase, an activated decrease of the resistance, followed by a susbstantial increase correlated to the formation of an open circuit. This degradation occurs more rapidly for the films having initially a lower resistance, due to the thermal dissipation which increases considerably the temperature to about 140 °C. Admittance spectra reveal, at low frequencies, a capacitive loop related to the formation of a charge space induced by copper diffusion. Such migration develop induces the formation of copper arborescences, spreading from the cathode towards the anode. The effect of these structures on the properties of the degraded films is discussed in relation to electromigration and associated processes (whiskers, fracture, healing, bridge-building, ...). Also, we have noticed their similarity with fractal phenomena such as electrodeposition and dielectric breakdown. Nous avons accéléré le vieillissement des couches minces de CuAlS2 par l'application d'un champ électrique statique pendant des durées variables. Nous avons fait appel à la spectroscopie d'admittance et la microscopie électronique à balayage, pour suivre et comprendre les processus de transport couplé (masse- charge) qui se produisent en volume et en surface de ces couches. L'effet de la contrainte électrique s'est traduit, après une phase d'incubation, par une décroissance activée de la résistance, suivie d'une phase d'emballement reliée à la formation d'un circuit ouvert. Cette fracturation se manifeste plus rapidement pour les couches ayant initialement une faible résistance, suite à l'effet de la

  11. Recent Developments in High-Temperature Shape Memory Thin Films

    Science.gov (United States)

    Motemani, Y.; Buenconsejo, P. J. S.; Ludwig, A.

    2015-11-01

    High-temperature shape memory alloy (HTSMA) thin films are candidates for development of microactuators with operating temperatures exceeding 100 °C. This article reviews recent advances and developments in the field of HTSMA thin films during the past decade, with focus on the systems Ti-Ni-X (X = Hf, Zr, Pd, Pt and Au), Ti-Ta, and Au-Cu-Al. These actuator films offer a wide range of transformation temperatures, thermal hysteresis, and recoverable strains suitable for high-temperature applications. Promising alloy compositions in the systems Ti-Ni-Hf, Ti-Ni-Pd, Ti-Ni-Au, and Au-Cu-Al are highlighted for further upscaling and development. The remaining challenges as well as prospects for development of HTSMA thin films are also discussed.

  12. Nanoparticle-lipid bilayer interactions studied with lipid bilayer arrays

    Science.gov (United States)

    Lu, Bin; Smith, Tyler; Schmidt, Jacob J.

    2015-04-01

    The widespread environmental presence and commercial use of nanoparticles have raised significant health concerns as a result of many in vitro and in vivo assays indicating toxicity of a wide range of nanoparticle species. Many of these assays have identified the ability of nanoparticles to damage cell membranes. These interactions can be studied in detail using artificial lipid bilayers, which can provide insight into the nature of the particle-membrane interaction through variation of membrane and solution properties not possible with cell-based assays. However, the scope of these studies can be limited because of the low throughput characteristic of lipid bilayer platforms. We have recently described an easy to use, parallel lipid bilayer platform which we have used to electrically investigate the activity of 60 nm diameter amine and carboxyl modified polystyrene nanoparticles (NH2-NP and COOH-NP) with over 1000 lipid bilayers while varying lipid composition, bilayer charge, ionic strength, pH, voltage, serum, particle concentration, and particle charge. Our results confirm recent studies finding activity of NH2-NP but not COOH-NP. Detailed analysis shows that NH2-NP formed pores 0.3-2.3 nm in radius, dependent on bilayer and solution composition. These interactions appear to be electrostatic, as they are regulated by NH2-NP surface charge, solution ionic strength, and bilayer charge. The ability to rapidly measure a large number of nanoparticle and membrane parameters indicates strong potential of this bilayer array platform for additional nanoparticle bilayer studies.The widespread environmental presence and commercial use of nanoparticles have raised significant health concerns as a result of many in vitro and in vivo assays indicating toxicity of a wide range of nanoparticle species. Many of these assays have identified the ability of nanoparticles to damage cell membranes. These interactions can be studied in detail using artificial lipid bilayers, which

  13. 热型连铸CuAlNi形状记忆合金线材的组织与力学性能%Microstructure and Mechanical Property of CuAlNi Shape Memory Alloy Wires Produced by Heated Mould Continuous Casting

    Institute of Scientific and Technical Information of China (English)

    李炳; 王鑫; 陈建; 范新会

    2011-01-01

    CuAINi shape memory alloy wires with 2.6 mm in diameter was produced by heated mould continuous casting using self-designed and manufactured equipment. The microstructure and mechanical properties of these wires were studied. The results show that the continuous casting speed has a decisive influence on the microstructure and mechanical properties of CuAINi alloy wires. CuAINi shape memory alloy wires with good surface quality can be prepared when the temperature is 1100℃ ~ 1150℃; casting speed is 75 mm/min; cooling distance is 15 mm and the cooling water is 60 L/h. The CuAINi shape memory alloy wires produced by heated mould continuous casting show a tensile strength of 288 Mpa and elongation of 9.43%.%在自制的热型连铸设备上,制备出了直径为2.6mm的CuAlNi形状记忆合金线材.并对线材的组织和力学性能进行了研究.结果表明:连铸速度对CuAlNi合金线材的组织和性能有决定性影响.当铸型温度为1100~1150℃、连铸速度为75 mm/min、冷却距离为15mm、冷却水量为60 L/h时,可制备出表面质量良好的CuAlNi形状记忆合金线材.热型连铸技术制备的CuAlNi形状记忆合金线材的抗拉强度为288MPa,断后伸长率为9.43%.

  14. One GHz leaky SAW velocity of metal layers and bilayers evaporated onto fused quartz

    Science.gov (United States)

    Walikainen, Dale

    1992-01-01

    An acoustic microscope operating at 1 GHz was used to determine the surface acoustic wave velocities v of thin film metal layers and metal bilayers deposited onto fused quartz. V(0)'s influence was reduced by gating. This produced a calibrated accuracy of 3 percent. A program was constructed from the explicitly solved 6 x 6 theoretical determinant. Single film thicknesses were decided upon by using this theory to produce a v equal to a standard. Since the single film v's were linear with respect to their thickness, half the single film thicknesses were used for the bilayered films. The velocities for these bilayered films agreed with theory. This experimentally confirms the theoretical technique used here to examine bilayered systems, or a prototype composite interphase. No discrepancy was seen for gold films as others have reported. V(z) seemed insensitive to the formation of intermetallics or CuO. Some annealed and unannealed platinum films did not change the v from that of fused quartz. Two platinum films whose v's were in agreement with theory peeled off with the tape test.

  15. Exchange bias training effect in coupled all ferromagnetic bilayer structures.

    Science.gov (United States)

    Binek, Ch; Polisetty, S; He, Xi; Berger, A

    2006-02-17

    Exchange coupled bilayers of soft and hard ferromagnetic thin films show remarkable analogies to conventional antiferromagnetic/ferromagnetic exchange bias heterostructures. Not only do all these ferromagnetic bilayers exhibit a tunable exchange bias effect, they also show a distinct training behavior upon cycling the soft layer through consecutive hysteresis loops. In contrast with conventional exchange bias systems, such all ferromagnetic bilayer structures allow the observation of training induced changes in the bias-setting hardmagnetic layer by means of simple magnetometry. Our experiments show unambiguously that the exchange bias training effect is driven by deviations from equilibrium in the pinning layer. A comparison of our experimental data with predictions from a theory based upon triggered relaxation phenomena shows excellent agreement.

  16. Lipid bilayer microarray for parallel recording of transmembrane ion currents.

    Science.gov (United States)

    Le Pioufle, Bruno; Suzuki, Hiroaki; Tabata, Kazuhito V; Noji, Hiroyuki; Takeuchi, Shoji

    2008-01-01

    This paper describes a multiwell biochip for simultaneous parallel recording of ion current through transmembrane pores reconstituted in planar lipid bilayer arrays. Use of a thin poly(p-xylylene) (parylene) film having micrometer-sized apertures (phi=15-50 microm, t=20 microm) led to formation of highly stable bilayer lipid membranes (BLMs) for incorporation of transmembrane pores; thus, a large number of BLMs could be arrayed without any skillful technique. We optically confirmed the simultaneous formation of BLMs in a 5x5 matrix, and in our durability test, the BLM lasted more than 15 h. Simultaneous parallel recording of alamethicin and gramicidin transmembrane pores in multiple contiguous recording sites demonstrated the feasibility of high-throughput screening of transmembrane ion currents in artificial lipid bilayers.

  17. Nd2Fe14B/α-Fe双层膜和多层梯度膜磁反转过程的微磁学模拟%Micromagnetic simulation on magnetization reversal process of Nd2Fe14B/α-Fe bilayers and multilayer gradient films

    Institute of Scientific and Technical Information of China (English)

    马建春; 张军; 薛玫

    2016-01-01

    利用微磁学有限差分计算方法,详细研究了软/硬磁层总厚度固定不变,结构的变化对Nd2Fe14B/α-Fe双层膜和 Nd2Fe14B/α-Fe/Nd2Fe14B 多层梯度膜的磁性能和磁反转过程的影响。结果表明,从双层膜变化到多层梯度膜的过程中,不同的结构具有不同的磁性能和磁反转过程;当结构优化为Nd2Fe14B(10 nm)/α-Fe(5 nm)/ Nd2Fe14B(10 nm)多层梯度膜时,磁滞回线台阶消失,矫顽力大幅度降低。此结论对交换耦合梯度介质的实验设置具有一定的指导意义。%Influence of structure on magnetic properties and magnetization reversal process of Nd2Fe14B/α-Fe bilayers and Nd2Fe14B/α-Fe/Nd2Fe14B multilayer gradient films were investigated by using micromagnetic simulation software OOMMF. The result shows that magnetization reversal process and magnetic properties change with the film structures changing from bilayers to multilayer gradient films; when the structure is optimized to Nd2Fe14B(10 nm)/α-Fe(5 nm)/Nd2Fe14B(10 nm) multilayer gradient films, the step of the hysteresis loop disappears, and the coercivity is reduced. The conculusion is of significant guidance to the experimental setting of exchange coupled gradient media.

  18. Molecular Dynamics of Lipid Bilayers

    Science.gov (United States)

    1989-08-09

    The aim of this work is to study, by molecular dynamics simulations, the properties of lipid bilayers. We have applied the vectorizable, order-N...fast angle-dependent force/potential algorithms to treat angle bending and torsion. Keywords: Molecular dynamics , Lipid bilayers.

  19. Entrenched metal lift-off using a novel bilayer process

    Science.gov (United States)

    Dubois, Thomas D.; Tranjan, Farid M.; Jones, Susan K.; Bobbio, Stephen M.; Kellam, Mark D.; Frieser, Rudolph G.; Jones, A. D.

    1990-01-01

    This paper will discuss the preparation and characterization of a modified photoresist and describe its use in a novel bilayer process. The modified photoresist solutions are prepared by dissolving enough cyclic phosphonitrilic chloride trimer, PNCT, in commercially available photoresist solutions to achieve phosphorus concentrations of 10 to 12 weight percent in the resulting films. FTNMR and FTIR data will be presented which demonstrate that the cyclic phosphonitrilic chloride trimer does not undergo chemical reaction with the components of the photoresist in the photoresist solutions or photoresist films. The exposure threshold of the PNCT modified photoresist films is 1.5 times greater than that of the unmodified films. Experimental data will be discussed which suggests the decrease in exposure threshold is the result of a relatively lower concentration of photoactive compound in the PNCT modified films. The PNCT modified films will be shown to provide resolution comparable to that of the unmodified photoresist films and yield a process window of better than 20%. A mechanism for the formation of the 02/N2 plasma resistant etch barrier formed during 02/N2 plasma etching will be discussed. Finally, a bilayer process which uses the PNCT modified photoresist in generating metal features entrenched in polyimide will be presented.

  20. A photoluminescence study of film structure in CdTe nanoparticle thin films.

    Science.gov (United States)

    Gardner, H C; Gallardo, D E; Dunn, S; Gaponik, N; Eychmüller, A

    2008-05-01

    The layer-by-layer deposition of thin films of CdTe nanoparticles and three different polyelectrolytes has been investigated. Photoluminescence spectra were used to monitor the energy transfer properties within the films. As the number of bilayers in a thin film was increased a decrease in the energy of the light emitted was observed. The wavelength change is a two-stage process. Deposition of the first one to two bi-layers of a thin film produced a sharp energy change (626 nm to 637 nm with the addition of a single bi-layer) whereas deposition of subsequent bi-layers produced a more gradual energy change (642 nm-646 nm with the addition of 5 bi-layers). A space-filling mechanism is suggested to account for these changes; smaller nanoparticles penetrate the earlier levels of a thin film and increase the inter-particle energy transfer opportunities within the layers.

  1. Exchange bias training effect in coupled all ferromagnetic bilayer structures

    Science.gov (United States)

    Polisetty, Srinivas; He, Xi; Binek, Christian; Berger, Andreas

    2006-03-01

    We study exchange coupled bilayers of soft and hard ferromagnetic (FM) thin films by means of Alternating Gradient Force Magnetometry. A CoCr thin film realizes the magnetically soft layer (SL) which is exchange coupled via a Ru-interlayer with a hard CoPtCrB pinning layer (HL). This new class of all FM bilayers shows remarkable analogies to conventional antiferromagnetic (AF)/FM exchange bias (EB) heterostructures. Not only do these all FM bilayers exhibit a tunable EB effect, they also show a distinct training behavior upon cycling the SL through consecutive hysteresis loops. Training resembles the cycle dependent evolution of the bias field and is to a large extend analogous to the gradual degradation of the EB field observed upon cycling the FM top layer of a AF/FM EB heterostructure through consecutive hysteresis loops. However, in contrast to these conventional EB systems, our all FM bilayer structures allow the observation of training induced changes in the bias-setting HL by means of simple magnetometry. Our experiments show unambiguously that the training effect is driven by deviations from equilibrium in the pinning layer. A comparison of the experimental data with predictions from a theory based upon triggered relaxation phenomena shows excellent agreement.

  2. Bursting Bubbles and Bilayers

    Directory of Open Access Journals (Sweden)

    Steven P. Wrenn, Stephen M. Dicker, Eleanor F. Small, Nily R. Dan, Michał Mleczko, Georg Schmitz, Peter A. Lewin

    2012-01-01

    Full Text Available This paper discusses various interactions between ultrasound, phospholipid monolayer-coated gas bubbles, phospholipid bilayer vesicles, and cells. The paper begins with a review of microbubble physics models, developed to describe microbubble dynamic behavior in the presence of ultrasound, and follows this with a discussion of how such models can be used to predict inertial cavitation profiles. Predicted sensitivities of inertial cavitation to changes in the values of membrane properties, including surface tension, surface dilatational viscosity, and area expansion modulus, indicate that area expansion modulus exerts the greatest relative influence on inertial cavitation. Accordingly, the theoretical dependence of area expansion modulus on chemical composition - in particular, poly (ethylene glyclol (PEG - is reviewed, and predictions of inertial cavitation for different PEG molecular weights and compositions are compared with experiment. Noteworthy is the predicted dependence, or lack thereof, of inertial cavitation on PEG molecular weight and mole fraction. Specifically, inertial cavitation is predicted to be independent of PEG molecular weight and mole fraction in the so-called mushroom regime. In the “brush” regime, however, inertial cavitation is predicted to increase with PEG mole fraction but to decrease (to the inverse 3/5 power with PEG molecular weight. While excellent agreement between experiment and theory can be achieved, it is shown that the calculated inertial cavitation profiles depend strongly on the criterion used to predict inertial cavitation. This is followed by a discussion of nesting microbubbles inside the aqueous core of microcapsules and how this significantly increases the inertial cavitation threshold. Nesting thus offers a means for avoiding unwanted inertial cavitation and cell death during imaging and other applications such as sonoporation. A review of putative sonoporation mechanisms is then presented

  3. Magnetoacoustic resonance in magnetoelectric bilayers

    Science.gov (United States)

    Filippov, D. A.; Bichurin, M. I.; Petrov, V. M.; Srinivasan, G.

    2004-03-01

    Layered composites of ferrite and ferroelectric single crystal thin films are of interest for studies on magnetoelectric interactions [1,2]. Such interactions result in unique and novel effects that are absent in single phase materials. For example, in a single crystal composite it is possible to control the ferromagnetic resonance (FMR) parameters for the ferrite by means of hypersonic oscillations induced in the ferroelectric phase. The absorption of acoustic oscillations by the ferrite results in variation in FMR line shape and power absorbed. One anticipates resonance absorption of elastic waves when the frequency of elastic waves coincides with the precession frequency of magnetization vector. This work is concerned with the nature of FMR under the influence of acoustic oscillations with the same frequency as FMR. Bilayers of ferrite and piezoelectric single crystals are considered. Hypersonic waves induced in the piezoelectric phase transmit acoustic power into ferrite due to mechanical connectivity between the phases. That transmission depends strongly on interface coupling [3]. We estimate the resulting variations in ferromagnetic resonance line shape. Estimates of magnetoelectric effect at magnetoacoustic resonance are also given. In addition, dependence of absorption of acoustic power on sample dimensions and compliances, electric and magnetic susceptibilities, piezoelectric and magnetostriction coefficients is discussed. The theory provided here is important for an understanding of interface coupling and the nature of magnetoelastic interactions in the composites. 1. M. I. Bichurin and V. M. Petrov, Zh. Tekh. Fiz. 58, 2277 (1988) [Sov. Phys. Tech. Phys. 33, 1389 (1988)]. 2. M.I. Bichurin, I. A. Kornev, V. M. Petrov, A. S. Tatarenko, Yu. V. Kiliba, and G. Srinivasan. Phys. Rev. B 64, 094409 (2001). 3. M. I. Bichurin, V. M. Petrov, and G. Srinivasan, J. Appl. Phys. 92, 7681 (2002). This work was supported by grants from the Russian Ministry of Education (

  4. Lipid bilayers on nano-templates

    Science.gov (United States)

    Noy, Aleksandr; Artyukhin, Alexander B.; Bakajin, Olgica; Stoeve, Pieter

    2009-08-04

    A lipid bilayer on a nano-template comprising a nanotube or nanowire and a lipid bilayer around the nanotube or nanowire. One embodiment provides a method of fabricating a lipid bilayer on a nano-template comprising the steps of providing a nanotube or nanowire and forming a lipid bilayer around the polymer cushion. One embodiment provides a protein pore in the lipid bilayer. In one embodiment the protein pore is sensitive to specific agents

  5. Magnetic properties of epitaxial bismuth ferrite-garnet mono- and bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Semuk, E.Yu.; Berzhansky, V.N.; Prokopov, A.R.; Shaposhnikov, A.N.; Karavainikov, A.V. [Taurida National V.I. Vernadsky University, Vernadsky Avenue, 4, 95007 Simferopol (Ukraine); Salyuk, O.Yu. [Institute of Magnetism NASU and MESU, 36-B Vernadsky Blvd., 03142 Kiev (Ukraine); Golub, V.O., E-mail: golub@imag.kiev.ua [Institute of Magnetism NASU and MESU, 36-B Vernadsky Blvd., 03142 Kiev (Ukraine)

    2015-11-15

    Magnetic properties of Bi{sub 1.5}Gd{sub 1.5}Fe{sub 4.5}Al{sub 0.5}O{sub 12} (84 nm) and Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} (180 nm) films epitaxially grown on gallium-gadolinium garnet (GGG) single crystal (111) substrate as well as Bi{sub 1.5}Gd{sub 1.5}Fe{sub 4.5}Al{sub 0.5}O{sub 12}/Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} bilayer were investigated using ferromagnetic resonance technique. The mismatch of the lattice parameters of substrate and magnetic layers leads to formation of adaptive layers which affect on the high order anisotropy constant of the films but practically do not affect on uniaxial perpendicular magnetic anisotropy The magnetic properties of the bilayer film were explained in supposition of strong exchange coupling between magnetic layers taking into account film-film and film-substrate elastic interaction. - Highlights: • Magnetic parameters of epitaxial Bi-YIG films and bilayers on GGG substrate. • Adaptive layers affect on high order magnetic anisotropy. • Magnetic properties of bilayers are result of strong exchange interaction.

  6. Effect of component substitution on the microstructure and mechanical properties of MCoCrFeNiTix (M = Cu,Al) solid-solution alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    MCoCrFeNiTix (M = Cu,Al;x:molar ratio,x = 0,0.5) alloys were prepared using the new alloy-design strategy of equal-atomic ratio and high entropy.By the component substitution of Al for Cu,the microstructure changes from the face-centered cubic solid solution of original CuCoCrFeNiTix alloys to the body-centered cubic solid solution of AICoCrFeNiTix alloys.Compared with original CuCoCrFeNiTix alloys,AICoCrFeNiTix alloys keep the similar good ductility and simultaneously possess a much higher compressive strength,which are even superior to most of the reported high-strength alloys like bulk metallic glasses.

  7. Experimental determination of interfacial energies for Ag2A1 solid solution in the CuAl2-Ag2Al system

    Institute of Scientific and Technical Information of China (English)

    Ocak Y; Akbulut S; Keslio(g)lu K; Mara(s)ll N; (C)adlrll E; Kaya H

    2009-01-01

    The equilibrated grain boundary groove shapes of solid solution Ag2Al in equilibrium with an Al-Cu-Ag liquid were observed from a quenched sample with a radial heat flow apparatus. The Gibbs-Thomson coefficient,solid-liquid interfacial energy and grain boundary energy of the solid solution Ag2Al have been determined from the observed grain boundary groove shapes. The thermal conductivity of the solid phase and the thermal conductivity ratio of the liquid phase to solid phase for Ag2Al-28.3 at the %CuAl2 alloy at the melting temperature have also been measured with a radial heat flow apparatus and Bridgman type growth apparatus,separately.

  8. Pedot and PPy Conducting Polymer Bilayer and Trilayer Actuators

    DEFF Research Database (Denmark)

    Zainudeen, Umer Lebbe; Careem, Mohamed Abdul; Skaarup, Steen

    2008-01-01

    Actuators based on conducting polymers are attracting increasing interest due to their desirable features such as large mechanical stress generated, sufficient maximum strain values, high reversibility, good safety properties and the possibility of precise control using small voltages. Many...... attempts have been made to improve the actuator performance. We report electromechanical measurements on actuators of bilayer and trilayer free standing films prepared with polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymers. Both types of conducting polymer are pre...

  9. FRACTURE OF AMORPHOUS BILAYER RIBBON

    NARCIS (Netherlands)

    Ocelik, Vaclav; DUHAJ, P; CSACH, K; MISKUF, J; BENGUS, VZ

    On the basis of measuring the mechanical properties and observing the fracture surface of an amorphous bilayer ribbon some partial conclusions on the mechanical quality of the bimetal boundary were drawn.

  10. The Influence of Al2O3 Powder Morphology on the Properties of Cu-Al2O3 Composites Designed for Functionally Graded Materials (FGM)

    Science.gov (United States)

    Strojny-Nędza, Agata; Pietrzak, Katarzyna; Węglewski, Witold

    2016-08-01

    In order to meet the requirements of an increased efficiency applying to modern devices and in more general terms science and technology, it is necessary to develop new materials. Combining various types of materials (such as metals and ceramics) and developing composite materials seem to be suitable solutions. One of the most interesting materials includes Cu-Al2O3 composite and gradient materials (FGMs). Due to their potential properties, copper-alumina composites could be used in aerospace industry as rocket thrusters and components in aircraft engines. The main challenge posed by copper matrix composites reinforced by aluminum oxide particles is obtaining the uniform structure with no residual porosity (existing within the area of the ceramic phase). In the present paper, Cu-Al2O3 composites (also in a gradient form) with 1, 3, and 5 vol.% of aluminum oxide were fabricated by the hot pressing and spark plasma sintering methods. Two forms of aluminum oxide (αAl2O3 powder and electrocorundum) were used as a reinforcement. Microstructural investigations revealed that near fully dense materials with low porosity and a clear interface between the metal matrix and ceramics were obtained in the case of the SPS method. In this paper, the properties (mechanical, thermal, and tribological) of composite materials were also collected and compared. Technological tests were preceded by finite element method analyses of thermal stresses generated in the gradient structure, and additionally, the role of porosity in the formation process of composite properties was modeled. Based on the said modeling, technological conditions for obtaining FGMs were proposed.

  11. Theory of skyrmions in bilayer systems

    Science.gov (United States)

    Koshibae, Wataru; Nagaosa, Naoto

    2017-02-01

    Skyrmion is an emergent particle consisting of many spins in magnets, and has many nontrivial features such as (i) nano-scale size, (ii) topological stability, (iii) gyrodynamics, and (iv) highly efficient spin transfer torque, which make skyrmions the promising candidate for the magnetic devices. Earlier works were focusing on the bulk or thin film of Dzyaloshinskii-Moriya (DM) magnets, while recent advances are focusing on the skyrmions induced by the interfaces. Therefore, the superstructures naturally leads to the interacting skyrmions on different interfaces, which has unique dynamics compared with those on the same interface. Here we theoretically study the two skyrmions on bilayer systems employing micromagnetic simulations as well as the analysis based on Thiele equation, revealing the reaction between them such as the collision and bound state formation. The dynamics depends sensitively on the sign of DM interactions, i.e., helicities, and skyrmion numbers of two skyrmions, which can be well described by Thiele equation. Furthermore, we have found the colossal spin-transfer-torque effect of bound skyrmion pair on antiferromagnetically coupled bilayer systems.

  12. A Bi-layer Composite Film Based on TiO2 Hollow Spheres, P25, and Multi-walled Carbon Nanotubes for Efficient Photoanode of Dye-sensitized Solar Cell

    Institute of Scientific and Technical Information of China (English)

    Putao Zhang; Zhiqiang Hu; Yan Wang; Yiying Qin; Wenqin Li; Jinmin Wang

    2016-01-01

    A bi-layer photoanode for dye-sensitized solar cell (DSSC) was fabricated, in which TiO2 hollow spheres (THSs) were designed as a scattering layer and P25/multi-walled carbon nanotubes (MWNTs) as an under-layer. The THSs were synthesized by a sacrifice template method and showed good light scattering ability as an over-layer of the pho-toanode. MWNTs were mixed with P25 to form an under-layer of the photoanode to improve the electron transmission ability of the photoanode. The power conversion efficiency of this kind of DSSC with bi-layer was enhanced to 5.13%, which is 14.25%higher than that of pure P25 DSSC. Graphical Abstract A bi-layer composite photoanode based on P25/MWNTs-THSs with improved light scattering and electron transmission, which will provide a new insight into fabrication and structure design of highly efficient dye-sensitized solar cells.

  13. On the comparison of the polarisation behaviour of exchange-biased AF/F NiMn/Fe{sub 37}Co{sub 48}Hf{sub 15} bi-layer and multi-layer films with increased ferromagnetic cut-off frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, K., E-mail: klaus.seemann@kit.edu [Karlsruhe Institute of Technology KIT (Campus North), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Leiste, H.; Krueger, K. [Karlsruhe Institute of Technology KIT (Campus North), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2012-03-15

    Antiferromagnetic/ferromagnetic (AF/F) NiMn/Fe{sub 37}Co{sub 48}Hf{sub 15} films were investigated with respect to their exchange bias, in-plane unidirectional anisotropy, polarisation and high frequency behaviour. After deposition, carried out by r.f. magnetron sputtering, the films were post-annealed for 4 h at 300 Degree-Sign C in a static magnetic field, in order to induce exchange-bias, which results in a unidirectional anisotropy. Dependent on the presence of a bi-layer or multi-layer sandwich structure the films show a different exchange-bias field-ferromagnetic inter-layer thickness behaviour with exchange-bias fields {mu}{sub 0} Low-Asterisk H{sub eb} between 2 and 10 mT. The in-plane uniaxial (single film) or unidirectional anisotropy fields {mu}{sub 0}*H{sub UF} were between 4 and 18 mT. This results in a significant increase of the cut-off frequency in the GHz range in comparison to a single Fe{sub 37}Co{sub 48}Hf{sub 15} film, which is shown by frequency-dependent permeability plots. High damping in the imaginary part of the permeability, i.e., high resonance line broadening could be observed for films with high coercivity {mu}{sub 0}*H{sub c} of around 7 mT in the easy axis of magnetisation. - Highlights: Black-Right-Pointing-Pointer Static and dynamic properties of NiMn/Fe{sub 37}Co{sub 48}Hf{sub 15} bi- and multi-layer films. Black-Right-Pointing-Pointer Theoretic analysis of the H{sub eb}- field difference of bi- and multi-layer films. Black-Right-Pointing-Pointer Two-stage magnetic process in the polarisation curves of the AF/F multi-layers. Black-Right-Pointing-Pointer Damping at the ferromagnetic permeability resonance state of AF/F multi-layers. Black-Right-Pointing-Pointer Derivation of the ferromagnetic resonance of AF/F multi-layer films.

  14. Possible influence of the ferromagnetic/antiferromagnetic interface on the effective critical behavior of bilayers based on La1-xSrxMnO3

    Science.gov (United States)

    Álvarez Miño, Lucero; Mulcué-Nieto, Luis Fernando

    2015-03-01

    In this work, the effective critical exponent of the spontaneous magnetization, β, and the transition temperature, TC, were calculated from magnetization measurements of three bilayers based on La1-xSrxMnO3 (LSMO). The bilayers structure is a ferromagnetic (FM) LSMO film grown on top of an antiferromagnetic (AF) LSMO film. The value of the antiferromagnetic film thickness was kept the same for the three samples, while the ferromagnetic film had different thickness for each bilayer. Applying a method of calculation based on a linear superposition of the magnetization close to the critical temperature, a β value corresponding to the 3D Ising model was found for the bilayer with the thinnest ferromagnetic film. This result, and the other obtained values are explained taking into account the possible influence of the FM/AF interface on the magnetic and crystal orderings.

  15. Quick photo-Fenton degradation of phenolic compounds by Cu/Al2O3-MCM-41 under visible light irradiation: small particle size, stabilization of copper, easy reducibility of Cu and visible light active material.

    Science.gov (United States)

    Pradhan, Amaresh C; Nanda, Binita; Parida, K M; Das, Mira

    2013-01-14

    The present study reports the photo-Fenton degradation of phenolic compounds (phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol) in aqueous solution using mesoporous Cu/Al(2)O(3)-MCM-41 nanocomposite as a heterogeneous photo-Fenton-like catalyst. The in situ incorporation of mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (sol-gel method) forms Al(2)O(3)-MCM-41 and wetness impregnation of Cu(II) on Al(2)O(3)-MCM-41 generates mesoporous Cu/Al(2)O(3)-MCM-41 composite. The effects of pH and H(2)O(2) concentration on degradation of phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol are studied. Kinetics analysis shows that the photocatalytic degradation reaction follows a first-order rate equation. Mesoporous 5 Cu/Al(2)O(3)-MCM-41 is found to be an efficient photo-Fenton-like catalyst for the degradation of phenolic compounds. It shows nearly 100% degradation in 45 min at pH 4. The combined effect of small particle size, stabilization of Cu(2+) on the support Al(2)O(3)-MCM-41, ease reducibility of Cu(2+) and visible light activeness are the key factors for quick degradation of phenolic compounds by Cu/Al(2)O(3)-MCM-41.

  16. Super-Sensitive and Robust Biosensors from Supported Polymer Bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Paxton, Walter F. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Biological organisms are potentially the most sensitive and selective biological detection systems known, yet we are currently severely limited in our ability to exploit biological interactions in sensory devices, due in part to the limited stability of biological systems and derived materials. This proposal addresses an important aspect of integrating biological sensory materials in a solid state device. If successful, such technology could enable entirely new classes of robust biosensors that could be miniaturized and deployed in the field. The critical aims of the proposed work were 1) the calibration of a more versatile approach to measuring pH, 2) the use of this method to monitor pH changes caused by the light-induced pumping of protons across vesicles with bacteriorhodopsin integrated into the membranes (either polymer or lipid); 3) the preparation of bilayer assemblies on platinum surfaces; 4) the enhanced detection of lightinduced pH changes driven by bR-loaded supported bilayers. I have developed a methodology that may enable that at interfaces and developed a methodology to characterize the functionality of bilayer membranes with reconstituted membrane proteins. The integrity of the supported bilayer films however must be optimized prior to the full realization of the work originally envisioned in the original proposal. Nevertheless, the work performed on this project and the encouraging results it has produced has demonstrated that these goals are challenging yet within reach.

  17. Enhanced sensitivity of a microfabricated resonator using a graphene-polystyrene bilayer membrane

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Minhyuk; Lee, Eunho; Cho, Kilwon; Jeon, Sangmin, E-mail: jeons@postech.ac.kr [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of)

    2014-08-18

    A graphene layer was synthesized using chemical vapor deposition methods and a polystyrene solution was spin-cast onto the graphene film. The graphene-polystyrene bilayer membrane was attached between the two tines of a microfabricated quartz tuning fork (QTF). The modulus of the graphene-polystyrene bilayer was measured to be twice that of a pristine polystyrene membrane. Exposure of the membrane-coated QTF to ethanol vapor decreased the resonance frequency of the microresonator. The bilayer membrane-coated QTF produced a frequency change that was three times the change obtained using a polystyrene membrane-coated QTF, with a lower degree of degradation in the Q factor. The limit of detection of the bilayer membrane-coated QTF to ethanol vapor was determined to be 20 ppm.

  18. Enhanced sensitivity of a microfabricated resonator using a graphene-polystyrene bilayer membrane

    Science.gov (United States)

    Yun, Minhyuk; Lee, Eunho; Cho, Kilwon; Jeon, Sangmin

    2014-08-01

    A graphene layer was synthesized using chemical vapor deposition methods and a polystyrene solution was spin-cast onto the graphene film. The graphene-polystyrene bilayer membrane was attached between the two tines of a microfabricated quartz tuning fork (QTF). The modulus of the graphene-polystyrene bilayer was measured to be twice that of a pristine polystyrene membrane. Exposure of the membrane-coated QTF to ethanol vapor decreased the resonance frequency of the microresonator. The bilayer membrane-coated QTF produced a frequency change that was three times the change obtained using a polystyrene membrane-coated QTF, with a lower degree of degradation in the Q factor. The limit of detection of the bilayer membrane-coated QTF to ethanol vapor was determined to be 20 ppm.

  19. Electromechanical oscillations in bilayer graphene

    Science.gov (United States)

    Benameur, Muhammed M.; Gargiulo, Fernando; Manzeli, Sajedeh; Autès, Gabriel; Tosun, Mahmut; Yazyev, Oleg V.; Kis, Andras

    2015-10-01

    Nanoelectromechanical systems constitute a class of devices lying at the interface between fundamental research and technological applications. Realizing nanoelectromechanical devices based on novel materials such as graphene allows studying their mechanical and electromechanical characteristics at the nanoscale and addressing fundamental questions such as electron-phonon interaction and bandgap engineering. In this work, we realize electromechanical devices using single and bilayer graphene and probe the interplay between their mechanical and electrical properties. We show that the deflection of monolayer graphene nanoribbons results in a linear increase in their electrical resistance. Surprisingly, we observe oscillations in the electromechanical response of bilayer graphene. The proposed theoretical model suggests that these oscillations arise from quantum mechanical interference in the transition region induced by sliding of individual graphene layers with respect to each other. Our work shows that bilayer graphene conceals unexpectedly rich and novel physics with promising potential in applications based on nanoelectromechanical systems.

  20. Aluminum surface layer strengthening using intense pulsed beam radiation of substrate film system

    Science.gov (United States)

    Klopotov, A. A.; Ivanov, Yu F.; Vlasov, V. A.; Kondratyuk, A. A.; Teresov, A. D.; Shugurov, V. V.; Petrikova, E. A.

    2016-11-01

    The paper presents formation of the substrate film system (Zr-Ti-Cu/Al) by electric arc spraying of cathode having the appropriate composition. It is shown that the intense beam radiation of the substrate film system is accompanied by formation of the multi-phase state, the microhardness of which exceeds the one of pure A7 aluminum by ≈4.5 times.

  1. Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part I. Microstructural Characterization of Rapidly Solidified Solders

    Science.gov (United States)

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

    2016-12-01

    Particles of Cu x Al y in Sn-Cu-Al solders have previously been shown to nucleate the Cu6Sn5 phase during solidification. In this study, the number and size of Cu6Sn5 nucleation sites were controlled through the particle size refinement of Cu x Al y via rapid solidification processing and controlled cooling in a differential scanning calorimeter. Cooling rates spanning eight orders of magnitude were used to refine the average Cu x Al y and Cu6Sn5 particle sizes down to submicron ranges. The average particle sizes, particle size distributions, and morphologies in the microstructures were analyzed as a function of alloy composition and cooling rate. Deep etching of the samples revealed the three-dimensional microstructures and illuminated the epitaxial and morphological relationships between the Cu x Al y and Cu6Sn5 phases. Transitions in the Cu6Sn5 particle morphologies from faceted rods to nonfaceted, equiaxed particles were observed as a function of both cooling rate and composition. Initial solidification cooling rates within the range of 103 to 104 °C/s were found to be optimal for realizing particle size refinement and maintaining the Cu x Al y /Cu6Sn5 nucleant relationship. In addition, little evidence of the formation or decomposition of the ternary- β phase in the solidified alloys was noted. Solidification pathways omitting the formation of the ternary- β phase agreed well with observed room temperature microstructures.

  2. Effect of milling duration on the evolution of shape memory properties in a powder processed Cu-Al-Ni-Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mohit; Gupta, Gaurav K.; Shafeeq, Muhamed M.; Modi, Om P.; Prasad, Braj K. [CSIR - Advanced Materials and Processes Research Institute, Bhopal (India)

    2013-09-15

    The present work describes the effect of milling duration on the properties of a powder metallurgy processed Cu-Al-Ni-Ti shape memory alloy employing mechanical alloying. Powder mixtures milled for different durations were sintered in order to investigate the formation of solid solution and evolution of martensitic structure. The idea was to optimize the duration of milling (mechanical alloying) to obtain chemical homogeneity as well as shape memory properties in the processed material without undergoing extensive post homogenization treatment. The martensitic structure was noted to evolve in the powder mix milled for at least 16 hrs, whereas complete transformation to martensite occurred after milling for 40 hrs. Interestingly, the dissolution of alloying elements (to form the {beta} phase prior to the formation of martensite) was noted to complete partially only during mechanical alloying for 40 hrs and remaining during subsequent sintering for 1 hr. The hot pressed compacts of the powders milled for 40 hrs were chemically homogeneous and consisted of fully martensite phase, which is essential for the realization of shape memory properties. They also revealed almost 100% shape recovery at the applied pre-strain levels of 1 and 2%. (orig.)

  3. Effect of two-stage isothermal annealing on microstructure CuAl10Fe5Ni5 bronze with additions of Si, Cr, Mo, W and C

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2011-07-01

    Full Text Available The aim of this study was to investigate the effect of a two-step isothermal annealing respectively at 1000 ̊C for 30 min, then at the range of 900÷450 ̊C increments 50 ̊C on the microstructure CuAl10 Ni5Fe5 bronze with additions of Si, Cr, Mo, W and C, cast into sand moulds. The study concerned the newly developed species, bronze, aluminium-iron-nickel with additions of Si, Cr, Mo, W and C. In order to determine the time and temperature for the characteristic of phase transitions that occur during heat treatment of the test method was used thermal and derivation analysis (TDA. The study was conducted on cylindrical test castings cast in the mould of moulding sand. It was affirmed that one the method TDA can appoint characteristic for phase transformations points about co-ordinates: τ (s, t ( ̊ C, and to plot out curves TTT for the studied bronze with their use. It was also found that there is a fiveisothermalannealingtemperatureranges significantly altering the microstructure of examined bronze.

  4. On the origin of residual strain in shape memory alloys: experimental investigation on evolutions in the microstructure of CuAlBe during complex thermomechanical loadings

    Science.gov (United States)

    Barati, M.; Arbab Chirani, S.; Kadkhodaei, M.; Saint-Sulpice, L.; Calloch, S.

    2017-02-01

    The behaviors of shape memory alloys (SMAs) strongly depend on the presence of different phases: austenite, thermally-induced martensite and stress-induced martensite. Consequently, it is important to know the phase volume fraction of each phases and their evolution during thermomechanical loadings. In this work, a three-phase proportioning method based on electric resistivity variation of a CuAlBe SMA is proposed. Simple thermomechanical loadings (i. e. pseudoplasticity and pseudoelasticity), one-way shape memory effect, recovery stress, assisted two-way memory effect at different level of stress and cyclic pseudoelasticity tests are investigated. Based on the electric resistivity results, during each loading path, evolution of the microstructure is determined. The origin of residual strain observed during the considered thermomechanical loadings is discussed. A special attention is paid to two-way shape memory effect generated after considered cyclic loadings and its relation with the developed residual strain. These results permit to identify and to validate the macroscopic models of SMAs behaviors.

  5. Effect of Nano CeO2 Addition on the Microstructure and Properties of a Cu-Al-Ni Shape Memory Alloy

    Science.gov (United States)

    Pandey, Abhishek; Jain, Ashish Kumar; Hussain, Shahadat; Sampath, V.; Dasgupta, Rupa

    2016-08-01

    This article deals with the effect of adding nano CeO2 to act as a grain pinner/refiner to a known Cu-Al-Ni shape memory alloy. Elements were taken in a predefined ratio to prepare 300 g alloy per batch and melted in an induction furnace. Casting was followed by homogenization at 1173 K (900 °C) and rolling to make sheets of 0.5-mm thickness. Further, samples were characterized for microstructure using optical and electron microscope, hardness, and different phase studies by X-ray and transformation temperatures by differential scanning calorimetry. X-ray peak broadenings and changes were investigated to estimate the crystallite size, lattice strain, and phase changes due to different processing steps. A nearly uniform distribution of CeO2 and better martensitic structure were observed with increasing CeO2. The addition of CeO2 also shows a visible effect on the transformation temperature and phase formation.

  6. Thermodynamic properties and mixing thermodynamic parameters of Ba-Al, Mg-Al, Sr-Al and Cu-Al metallic melts

    Institute of Scientific and Technical Information of China (English)

    张鉴

    2004-01-01

    Application of equations of mixing thermodynamic parameters formulated on the basis of the coexistence theory of metallic melts in Ba-Al, Mg-Al, Sr-A1 and Cu-Al melts leads to fruitful results that not only the evaluated mass action concentrations agree well with the measured activities, but also the calculated mixing thermodynamic parameters are quite coincident with the experimental values. Moreover, the calculated mass action concentrations strictly obey the mass action law. The evaluated mixing thermodynamic parameters have very fine regularity: the mixing free energy is composed of standard free formation energies of all compounds and chemical potentials of all structural units at equilibrium; the mixing enthalpy consists of standard formation enthalpies of all compounds; the mixing entropy is composed of standard entropies of all compounds and configuration entropies of all structural units at equilibrium. As the equations of mixing thermodynamic parameters formulated are widely applicable to metallic melts involving compound formation, they can be used as the second practical criterion to determine whether thermodynamic models of metallic melts are correctly formulated.

  7. Parametric study of the decomposition of methane using a NiCu/Al{sub 2}O{sub 3} catalyst in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pinilla, J.L.; Suelves, I.; Lazaro, M.J.; Moliner, R. [Instituto de Carboquimica, CSIC, Miguel Luesma Castan 4, 50018 Zaragoza (Spain); Palacios, J.M. [Instituto de Catalisis y Petroleoquimica, CSIC, Campus Universidad Autonoma, Cantoblanco, 28049 Madrid (Spain)

    2010-09-15

    CO{sub 2}-free production of hydrogen via catalytic decomposition of methane (CDM) was studied in a fluidized bed reactor (FBR) using a NiCu/Al{sub 2}O{sub 3} catalyst. A parametric study of the effects of some process variables, including catalyst particle size, reaction temperature, space velocity and the ratio of gas flow velocity to the minimum fluidization velocity (u{sub o}/u{sub mf}), was undertaken. A mean particle size of 150 {mu}m allows optimization of results in terms of hydrogen production without agglomeration problems. The operating conditions strongly affect the catalyst performance: hydrogen production was enhanced by increasing operating temperature and lowering space velocity. However, increases in operating temperature, space velocity and the ratio u{sub o}/u{sub mf} provoked increases in the catalyst deactivation rate. At 700 C, carbon was deposited as carbon nanofibers, while higher temperatures promoted the formation of encapsulating carbon, which led to rapid catalyst deactivation. (author)

  8. Microstructural and superficial modification in a Cu-Al-Be shape memory alloy due to superficial severe plastic deformation under sliding wear conditions

    Science.gov (United States)

    Figueroa, C. G.; Garcia-Castillo, F. N.; Jacobo, V. H.; Cortés-Pérez, J.; Schouwenaars, R.

    2017-05-01

    Stress induced martensitic transformation in copper-based shape memory alloys has been studied mainly in monocrystals. This limits the use of such results for practical applications as most engineering applications use polycristals. In the present work, a coaxial tribometer developed by the authors was used to characterise the tribological behaviour of polycrystalline Cu-11.5%Al-0.5%Be shape memory alloy in contact with AISI 9840 steel under sliding wear conditions. The surface and microstructure characterization of the worn material was conducted by conventional scanning electron microscopy and atomic force microscopy, while the mechanical properties along the transversal section were measured by means of micro-hardness testing. The tribological behaviour of Cu-Al-Be showed to be optimal under sliding wear conditions since the surface only presented a slight damage consisting in some elongated flakes produced by strong plastic deformation. The combination of the plastically modified surface and the effects of mechanically induced martensitic transformation is well-suited for sliding wear conditions since the modified surface provides the necessary strength to avoid superficial damage while superelasticity associated to martensitic transformation is an additional mechanism which allows absorbing mechanical energy associated to wear phenomena as opposed to conventional ductile alloys where severe plastic deformation affects several tens of micrometres below the surface.

  9. CuAl{sub 1-x}In{sub x}Se{sub 2} solid solutions: Dielectric function and inter-band optical transitions

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Yong Gu [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Sakai, Osaka 599-8531 (Japan)], E-mail: shim@pe.osakafu-u.ac.jp; Hasegawa, Kouji [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Sakai, Osaka 599-8531 (Japan); Wakita, Kazuki [Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1, Tsudanuma, Narashino, Chiba 275-0016 (Japan); Mamedov, Nazim [Institute of Physics, National Academy of Sciences of Azerbaijan, Javid ave. 33, Baku, AZ-1143 (Azerbaijan)

    2008-12-31

    The dielectric function of bulk CuAl{sub 1-x}In{sub x}Se{sub 2} with composition x varying from x = 0.07 to x = 0.6 were studied over the photon energy region 1.0-6.0 eV at room temperature by spectroscopic ellipsometry. Information on the inter-band optical transitions was obtained from the results of the standard critical point analysis of the obtained dielectric function. With increasing Indium content, all spectral features of the obtained dielectric functions were found to gradually shift towards lower energies. The details of this shift for each critical point retrieved from the obtained dielectric function were disclosed. A compositional dependence of the optical transitions in {gamma} point of the Brillouin zone was verified to be strong. Such dependence for N and T points turned out to be weak by comparison. The later fact was accounted for a small compositional shift of the conduction band states in N and T points as compared to {gamma} point.

  10. Feasibility of externally activated self-repairing concrete with epoxy injection network and Cu-Al-Mn superelastic alloy reinforcing bars

    Science.gov (United States)

    Pareek, Sanjay; Shrestha, Kshitij C.; Suzuki, Yusuke; Omori, Toshihiro; Kainuma, Ryosuke; Araki, Yoshikazu

    2014-10-01

    This paper studies the effectiveness of an externally activated self-repairing technique for concrete members with epoxy injection network and Cu-Al-Mn superelastic alloy (SEA) reinforcing bars (rebars). Compared to existing crack self-repairing and self-healing techniques, the epoxy injection network has the following strengths: (1) Different from the self-repairing methods using brittle containers or tubes for adhesives, the proposed self-repair process can be performed repeatedly and is feasible for onsite concrete casting. (2) Different from the autogenic self-healing techniques, full strength recovery can be achieved in a shorter time period without the necessity of water. This paper attempts to enhance the self-repairing capability of the epoxy injection network by reducing residual cracks by using cost-effective Cu-based SEA bars. The effectiveness of the present technique is examined using concrete beam specimens reinforced by 3 types of bars. The first specimen is reinforced by steel deformed bars, the second by steel threaded bars, and finally by SEA threaded rebars. The tests were performed with a 3 point cyclic loading with increasing amplitude. From the test results, effective self-repairing was confirmed for small deformation levels irrespective of the reinforcement types. Effective self-repairing was observed in the SEA reinforced specimen even under much larger deformations. Nonlinear finite element analysis was performed to confirm the experimental findings.

  11. Selective hydrogenolysis of biomass-derived furfuryl alcohol into 1,2-and 1,5-pentanediol over highly dispersed Cu-Al2O3 catalysts%高分散Cu-Al2O3催化剂选择氢解生物质基糠醇制备1,2-和1,5-戊二醇

    Institute of Scientific and Technical Information of China (English)

    刘海龙; 黄志威; 康海笑; 夏春谷; 陈静

    2016-01-01

    生物质是唯一可再生的有机碳资源,开发清洁高效稳定的催化剂体系,将富氧的生物质及其平台化合物高选择性的C–O键氢解转化为可供石化行业利用的高附加值产品成为当前的研究热点.糠醛可由农林副产物如玉米芯,甘蔗渣和秸秆等中富含的半纤维素经酸水解而得.采用便宜的糠醛及其衍生物糠醇和四氢糠醇为原料,通过温和条件下一步选择氢解合成高附加值的1,2-和/或1,5-戊二醇的研究受到了越来越多的关注,但目前的研究主要集中在Ru, Rh, Pt和Ir等贵金属催化剂,对无铬非贵金属催化剂的研究甚少;此外,目前文献报道催化剂的活性和选择性还有待提高.开发清洁高效的非贵金属催化剂在温和条件下选择氢解糠醇或糠醛是目前面临的一项难题.我们的最新研究发现采用以水滑石为前驱体制备的弱碱性Cu-Mg3AlO4.5双功能催化剂在糠醇选择氢解反应中表现出优异的催化性能,在413 K和6 MPa的温和条件下可取得约80%的戊二醇总收率.虽然碱性载体有利于稳定糠醇氢解中间体并抑制羟基脱水从而提高戊二醇选择性,但也有文献报道酸性载体或助剂同样对呋喃衍生物的选择氢解制二元醇有促进作用.为了研究固体酸负载的双功能催化剂在糠醇氢解中的催化性能,我们采用共沉淀法制备了酸性Al2O3载体分散的不同Cu含量(2–30 wt%)的纳米双功能催化剂,并对比考察了其他不同载体(SiO2, TiO2, ZrO2, MgO和ZnO)负载的催化剂, Al2O3负载的Ni, Co和Pt催化剂及商业Cu-Cr催化剂的糠醇氢解性能.研究发现,在金属负载量相同时, Cu-Al2O3催化剂表现出最优异的糠醇氢解性能,而Cu-Al2O3催化剂的转化率随Cu铜含量的升高先增高后降低,在20 wt%时达最高,而戊二醇的总选择性在10 wt%时达最高.  为了揭示Cu-Al2O3催化剂在糠醇氢解反应中的构效关系,采用X

  12. Transport limits in defect-engineered LaAlO3/SrTiO3 bilayers

    NARCIS (Netherlands)

    Gunkel, F.; Wicklein, S.; Hoffmann-Eifert, S.; Meuffels, P.; Brinks, Peter; Huijben, Mark; Waser, R.; Dittmann, R.

    2014-01-01

    The electrical properties of the metallic interface in LaAlO3/SrTiO3 (LAO/STO) bilayers are investigated with focus on the role of cationic defects in thin film STO. Systematic growth-control of the STO thin film cation stoichiometry (defect-engineering) yields a relation between cationic defects in

  13. Layer-resolved photoemission tomography: The p -sexiphenyl bilayer upon Cs doping

    Science.gov (United States)

    Reinisch, E. M.; Puschnig, P.; Ules, T.; Ramsey, M. G.; Koller, G.

    2016-04-01

    The buried interface between a molecular thin film and the metal substrate is generally not accessible to the photoemission experiment. With the example of a sexiphenyl (6 P ) bilayer on Cu we show that photoemission tomography can be used to study the electronic level alignment and geometric structure, where it was possible to assign the observed orbital emissions to the individual layers. We further study the Cs doping of this bilayer. Initial Cs exposure leads to a doping of only the first interface layer, leaving the second layer unaffected except for a large energy shift. This result shows that it is in principle possible to chemically modify just the interface, which is important to issues like tuning of the energy level alignment and charge transfer to the interface layer. Upon saturating the film with Cs, photoemission tomography shows a complete doping (6 p4 - ) of the bilayer, with the molecular geometry changing such that the spectra become dominated by σ -orbital emissions.

  14. Fruit and vegetable films and uses thereof

    Science.gov (United States)

    The present invention is directed to monolayer, bilayer, and multilayer films made from fruit, vegetable or a combination thereof, which films have the thinness, strength, flexibility and crispness to serve as alternates or substitutes for seaweed-based films such as nori, while providing nutrition ...

  15. Crystal growth, structure, and physical properties of Ln(Cu,Al)12 (Ln = Y, Ce, Pr, Sm, and Yb) and Ln(Cu, Ga)12 (Ln = Y, Gd-Er, and Yb).

    Science.gov (United States)

    Drake, Brenton L; Capan, C; Cho, Jung Young; Nambu, Y; Kuga, K; Xiong, Y M; Karki, A B; Nakatsuji, S; Adams, P W; Young, D P; Chan, Julia Y

    2010-02-17

    Single crystals of Ln(Cu,Al)12 and Ln(Cu,Ga)12 compounds (Ln = Y, Ce-Nd, Sm, Gd-Ho, and Yb for Al and Ln = Y, Gd-Er, Yb for Ga) have been grown by flux-growth methods and characterized by means of single-crystal x-ray diffraction, complemented with microprobe analysis, magnetic susceptibility, resistivity and heat capacity measurements. Ln(Cu,Ga)12 and Ln(Cu,Al)12 of the ThMn12 structure type crystallize in the tetragonal I4/mmm space group with lattice parameters a approximately 8.59 Å and c approximately 5.15 Å and a approximately 8.75 Å and c approximately 5.13 Å for Ga and Al containing compounds, respectively. For aluminium containing compounds, magnetic susceptibility data show Curie-Weiss paramagnetism in the Ce and Pr analogues down to 50 K with no magnetic ordering down to 3 K, whereas the Yb analogue shows a temperature-independent Pauli paramagnetism. Sm(Cu,Al)12 orders antiferromagnetically at T(N)approximately 5 K and interestingly exhibits Curie-Weiss behaviour down to 10 K with no Van Vleck contribution to the susceptibility. Specific heat data show that Ce(Cu,Al)12 is a heavy fermion antiferromagnet with T(N) approximately 2 K and with an electronic specific heat coefficient γ0 as large as 390 mJ K2 mol(-1). In addition, this is the first report of Pr(Cu,Al)12 and Sm(Cu,Al)12 showing an enhanced mass (approximately 80 and 120 mJ K(2) mol(-1)). For Ga containing analogues, magnetic susceptibility data also show the expected Curie-Weiss behaviour from Gd to Er, with the Yb analogue being once again a Pauli paramagnet. The antiferromagnetic transition temperatures range over 12.5, 13.5, 6.7, and 3.4 K for Gd, Tb, Dy, and Er. Metallic behaviour is observed down to 3 K for all Ga and Al analogues. A large positive magnetoresistance up to 150% at 9 T is also observed for Dy(Cu,Ga)12. The structure, magnetic, and transport properties of these compounds will be discussed.

  16. In-situ investigation on the growth of Cu-Al intermetallic comp ounds in Cu wire b onding%Cu/Al引线键合界面金属间化合物生长过程的原位实验研究∗

    Institute of Scientific and Technical Information of China (English)

    杨庆龄; 陈奕仪; 吴幸; 沈国瑞; 孙立涛

    2015-01-01

    According to Moore’s Law, as the feature size of semiconductor devices becoming smaller and smaller, the chip integration degree keeps increasing. In particular, accompanying with the development of high chip integration and unit size reduction, the metal interconnects, i. e. the wire bonding, are becoming a challenging problem. Copper wire is believed to be an excellent metal for wire bonding, instead of gold wire, due to its attractive advantages such as low cost, favorable electrical and thermal conductivities etc. However, the excess Cu/Al intermetallic compounds (IMC) at the interface of copper wire and aluminum pad will increase the contact resistance and reduce bonding strength. This can affect the properties and reliability of devices. Currently, the evolutions of the interfacial microstructures as well as the growth mechanism of Cu/Al IMC at the bonding interface under thermal condition are still unclear. In-situ transmission electron microscope (TEM) has high spatial resolution and strong analysis ability. With fast CCD cameras, TEM can also record the dynamic structure evolution of the sample in real time. Combined with multi-function holders, TEM can also exert diverse fields and loads on the sample and synchronously monitor their structures and component evolutions. Hence, in situ TEM provides an advanced technique to explore the structural evolution and growth mechanism of Cu/Al IMC. In this paper, the growth mechanism of Cu/Al IMC is investigated during the annealing temperature from 50–220◦C based on the in-situ high resolution transmission electron microscopy (in-situ HRTEM). Specifically, the dynamic growth and structural evolution of Cu/Al IMC during annealing are recorded in real time. Results show that the isolated Cu/Al IMC is distributed in the bonding interface before annealing. The main component of IMC is Cu9Al4, whereas the minor one of IMC is CuAl2. After annealing at 50–220 ◦C for 24 h, Cu/Al IMC near the Cu layer is Cu9Al4

  17. Metal thin film growth on multimetallic surfaces: From quaternary metallic glass to binary crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Dapeng [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    The work presented in this thesis mainly focuses on the nucleation and growth of metal thin films on multimetallic surfaces. First, we have investigated the Ag film growth on a bulk metallic glass surface. Next, we have examined the coarsening and decay of bilayer Ag islands on NiAl(110) surface. Third, we have investigated the Ag film growth on NiAl(110) surface using low-energy electron diffraction (LEED). At last, we have reported our investigation on the epitaxial growth of Ni on NiAl(110) surface. Some general conclusions can be drawn as follows. First, Ag, a bulk-crystalline material, initially forms a disordered wetting layer up to 4-5 monolayers on Zr-Ni-Cu-Al metallic glass. Above this coverage, crystalline 3D clusters grow, in parallel with the flatter regions. The cluster density increases with decreasing temperature, indicating that the conditions of island nucleation are far-from-equilibrium. Within a simple model where clusters nucleate whenever two mobile Ag adatoms meet, the temperature-dependence of cluster density yields a (reasonable) upper limit for the value of the Ag diffusion barrier on top of the Ag wetting layer of 0.32 eV. Overall, this prototypical study suggests that it is possible to grow films of a bulk-crystalline metal that adopt the amorphous character of a glassy metal substrate, if film thickness is sufficiently low. Next, the first study of coarsening and decay of bilayer islands has been presented. The system was Ag on NiAl(110) in the temperature range from 185 K to 250 K. The coarsening behavior, has some similarities to that seen in the Ag(110) homoepitaxial system studied by Morgenstern and co-workers. At 185 K and 205 K, coarsening of Ag islands follows a Smoluchowski ripening pathway. At 205 K and 250 K, the terrace diffusion limited Ostwald ripening dominants. The experimental observed temperature for the transition from SR to OR is 205 K. The SR exhibits anisotropic island diffusion and the OR exhibits 1D decay of island

  18. Broadband ferromagnetic resonance characterization of anisotropies and relaxation in exchange-biased IrMn/CoFe bilayers

    Science.gov (United States)

    Beik Mohammadi, Jamileh; Jones, Joshua Michael; Paul, Soumalya; Khodadadi, Behrouz; Mewes, Claudia K. A.; Mewes, Tim; Kaiser, Christian

    2017-02-01

    The magnetization dynamics of exchange-biased IrMn/CoFe bilayers have been investigated using broadband and in-plane angle-dependent ferromagnetic resonance spectroscopy. The interface energy of the exchange bias effect in these bilayers exceeds values previously reported for metallic antiferromagnets. A strong perpendicular magnetic anisotropy and a small in-plane uniaxial anisotropy are also observed in these films. The magnetization relaxation of the bilayers has a strong unidirectional contribution, which is in part caused by two-magnon scattering. However, a detailed analysis of in-plane angle- and thickness-dependent linewidth data strongly suggests the presence of a previously undescribed unidirectional relaxation mechanism.

  19. Effect of High-Entropy Components of Nitride Layers on Nitrogen Content and Hardness of (TiN-Cu/(AlNbTiMoVCrN Vacuum-Arc Multilayer Coatings

    Directory of Open Access Journals (Sweden)

    V.М. Beresnev

    2016-06-01

    Full Text Available An integrated research of links in the “content-structure-properties” chain in structural engineering of (TiN-Cu/(AlNbTiMoVCrN multilayer coatings was carried out with application of elemental and X-ray diffraction analysis as well as microhardness testing. It has been found that formation of the second layer based on a high-entropy alloy even with a relatively small content of components (below 1 wt % leads to formation of a solid solution FCC lattice phase. Compared to TiN-Cu singlelayer coatings, the multilayer coating based on a (TiN-Cu/(AlNbTiMoVCrN system has an increased nitrogen content and an enhanced hardness of up to 24.5 GPa.

  20. The Effect of Toughening Combined with Microjet Cooling During Quenching (Solution Heat Treatment of Calcium Carbide-modified CuAl10Fe4Ni4 Alloy on its Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Z. Górny

    2013-01-01

    Full Text Available The work presents the results of the experimental research concerning the impact of a heat treatment (toughening of aluminum bronze CuAl10Fe4Ni4 on its mechanical properties. The conditions of the experiments and selected results are described. A detailed description of the effects of individual heat treatment conditions namely low and high temperature aging is also presented in the work.

  1. Effect of Annealing Time for Quenching CuAl7Fe5Ni5W2Si2 Bronze on the Microstructure and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2012-04-01

    Full Text Available This paper presents the influence of annealing time 30, 60 and 120 min at 1000°C for quenching CuAl7Fe5Ni5W2Si2 bronze in 10% water solution of NaCl, on the microstructure and mechanical properties. The presented results concern the species newly developed aluminum-iron-nickel bronze, with additions W and Si.In order to determine changes in the microstructure of the hardened bronze metallographic studies were performed on cylindrical samples of diameter 10 mm, on the metallographic microscope with digital image analysis, X-ray phase analysis, EDX point with the digital recording on the computer. Specified percentage of the microstructure of martensite and bainite, participation of proeutectoid α phase in the microstructure, grain size of former β phase, the amount of dissolved κ phase.It was found that in the microstructure of bronze in the cast state, there are a number of intermetallic phases of κ type. At interphase boundaries of primary intermetallic faceted precipitates, especially rich in tungsten (IM_W, nucleate and grow dendritic primary intermetallic κI phases, with chemical composition similar to the type of Fe3Si iron silicide.Dissolved, during the heating, in the β phase are all the intermediate phase included in the microstructure, with the exception of primary intermetallic phases of tungsten and κI. Prolongation of the isothermal annealing causes coagulation and coalescence of primary phases. In microstructure of the bronze after quenching obtained the α phase precipitation on the grain boundary of secondary β phase, coarse bainite and martensite, for all annealing times. With the change of annealing time are changed the relative proportions of individual phases or their systems, in the microstructure. In the microstructure of bronze, hold at temperature of 1000°C for 60 min, after quenching martensitic microstructure was obtained with the primary phases, and the least amount of bainite.

  2. Enhanced photocatalytic and adsorptive degradation of organic dyes by mesoporous Cu/Al2O3-MCM-41: intra-particle mesoporosity, electron transfer and OH radical generation under visible light.

    Science.gov (United States)

    Pradhan, Amaresh C; Parida, K M; Nanda, Binita

    2011-07-28

    Mesoporous Cu/Al(2)O(3)-MCM-41 composite was synthesized by two step processes; in situ incorporation of high surface area mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (in situ method) followed by impregnation of Cu(II) by incipient wetness method. The interesting thing is that starch was used for the first time as template for the preparation of high surface area MA. To evaluate the structural and electronic properties, these catalysts were characterized by low angle X-ray diffraction (LXRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-vis DRS, FTIR and photoluminescent (PL) spectra. The various cationic dye such as methylene blue (MB), methyl violet (MV), malachite green (MG) and rhodamine 6G (Rd 6G) of high concentration 500 mg L(-1) were degraded and adsorbed very efficiently (100%) using the 5 Cu/Al(2)O(3)-MCM-41 composite within 30 and 60 min, respectively. The high and quick removal of such concerted cationic organic dyes and also mixed dyes (MB+MV+MG+Rd 6G) by means of photocatalysis/adsorption is basically due to the combined effect three characteristics of synthesized mesoporous 5 Cu/Al(2)O(3)-MCM-41 composite. These characteristics are intra-particle mesoporosity, electron transfer and ˙OH radical generation under solar light.

  3. Chemical Trend of Superconducting Critical Temperatures in Hole-Doped CuBO2, CuAlO2, CuGaO2, and CuInO2

    Science.gov (United States)

    Nakanishi, Akitaka; Katayama-Yoshida, Hiroshi; Ishikawa, Takahiro; Shimizu, Katsuya

    2016-09-01

    We calculated the superconducting critical temperature (Tc) for hole-doped CuXO2 (X = B, Al, Ga, and In) compounds using first-principles calculations based on rigid band model. The compounds with X = Al, Ga, and In have delafosite-type structures and take maximum Tc values at 0.2-0.3 with respect to the number of holes (Nh) in the unit-cell: 50 K for CuAlO2, 10 K for CuGaO2, and 1 K for CuInO2. The decrease of Tc for this change in X is involved by covalency reduction and lattice softening associated with the increase of ionic mass and radius. For CuBO2 which is a lighter compound than CuAlO2, the delafosite structure is unstable and a body-centered tetragonal structure emerges as the most stable structure. As the results, the electron-phonon interaction is decreased and Tc is lower by approximately 43 K than that of CuAlO2 at the hole-doping conditions of Nh = 0.2-0.3.

  4. Bilayer Effects of Antimalarial Compounds.

    Directory of Open Access Journals (Sweden)

    Nicole B Ramsey

    Full Text Available Because of the perpetual development of resistance to current therapies for malaria, the Medicines for Malaria Venture developed the Malaria Box to facilitate the drug development process. We tested the 80 most potent compounds from the box for bilayer-mediated effects on membrane protein conformational changes (a measure of likely toxicity in a gramicidin-based stopped flow fluorescence assay. Among the Malaria Box compounds tested, four compounds altered membrane properties (p< 0.05; MMV007384 stood out as a potent bilayer-perturbing compound that is toxic in many cell-based assays, suggesting that testing for membrane perturbation could help identify toxic compounds. In any case, MMV007384 should be approached with caution, if at all.

  5. Deposition and aggregation of aspirin molecules on a phospholipid bilayer pattern.

    Science.gov (United States)

    Mao, Guangzhao; Chen, Dongzhong; Handa, Hitesh; Dong, Wenfei; Kurth, Dirk G; Möhwald, Helmuth

    2005-01-18

    Aspirin and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) are deposited from their alcoholic mixed solution onto highly oriented pyrolytic graphite (HOPG) by spin coating. The film structure and morphology are characterized by atomic force microscopy (AFM). The barely soluble DMPE forms a highly oriented stripe phase as a result of its one-dimensional epitaxy with the HOPG lattice. The bilayer stripe pattern exposes the cross section of the lipid bilayer lamellae and enables the direct visualization of the molecular interactions of drug or biological molecules with either the hydrophobic or the hydrophilic part of the phospholipid bilayer. The bilayer pattern affects the aspirin molecular deposition and aggregation. AFM shows that the aspirin molecules prefer to deposit and aggregate along the aliphatic interior part of the bilayer pattern, giving rise to parallel dimer rods in registry with the underlying pattern. The nonpolar interactions between aspirin and the phospholipid bilayer are consistent with the lipophilic nature of aspirin. The bilayer pattern not only stabilizes the rodlike aggregate structure of aspirin at low aspirin concentration but also inhibits crystallization of aspirin at high aspirin concentration. Molecular models show that the width of the DMPE aliphatic chain interior can accommodate no more than two aspirin dimers. The bilayer confinement may prevent aspirin from reaching its critical nucleus size. This study illustrates a general method to induce a metastable or amorphous form of an active pharmaceutical ingredient (API) by chemical confinement under high undercooling conditions. Metastable and amorphous solids often display better solubility and bioavailability than the stable crystalline form of the API.

  6. Computer Simulations of Lipid Bilayers and Proteins

    DEFF Research Database (Denmark)

    Sonne, Jacob

    2006-01-01

    , Pressure profile calculations in lipid bilayers: A lipid bilayer is merely $\\sim$5~nm thick, but the lateral pressure (parallel to the bilayer plane) varies several hundred bar on this short distance (normal to the bilayer). These variations in the lateral pressure are commonly referred to as the pressure...... of neglecting pressure contributions from long range electrostatic interactions. The first issue is addressed by comparing two methods for calculating pressure profiles, and judged by the similar results obtained by these two methods the pressure profile appears to be well-defined for fluid phase lipid bilayers......The importance of computer simulations in lipid bilayer research has become more prominent for the last couple of decades and as computers get even faster, simulations will play an increasingly important part of understanding the processes that take place in and across cell membranes. This thesis...

  7. Horizontal Bilayer for Electrical and Optical Recordings

    Directory of Open Access Journals (Sweden)

    Alf Honigmann

    2012-12-01

    Full Text Available Artificial bilayer containing reconstituted ion channels, transporters and pumps serve as a well-defined model system for electrophysiological investigations of membrane protein structure–function relationship. Appropriately constructed microchips containing horizontally oriented bilayers with easy solution access to both sides provide, in addition, the possibility to investigate these model bilayer membranes and the membrane proteins therein with high resolution fluorescence techniques up to the single-molecule level. Here, we describe a bilayer microchip system in which long-term stable horizontal free-standing and hydrogel-supported bilayers can be formed and demonstrate its prospects particularly for single-molecule fluorescence spectroscopy and high resolution fluorescence microscopy in probing the physicochemical properties like phase behavior of the bilayer-forming lipids, as well as in functional studies of membrane proteins.

  8. Chemically deposited TiO2/CdS bilayer system for photoelectrochemical properties

    Indian Academy of Sciences (India)

    P R Deshmukh; U M Patil; K V Gurav; S B Kulkarni; C D Lokhande

    2012-12-01

    In the present investigation, TiO2, CdS and TiO2/CdS bilayer system have been deposited on the fluorine doped tin oxide (FTO) coated glass substrate by chemical methods. Nanograined TiO2 was deposited on FTO coated glass substrates by successive ionic layers adsorption and reaction (SILAR) method. Chemical bath deposition (CBD)method was employed to deposit CdS thin film on pre-deposited TiO2 film. A further study has beenmade for structural, surface morphological, optical and photoelectrochemical (PEC) properties of FTO/TiO2, FTO/CdS and FTO/TiO2/CdS bilayers system. PEC behaviour of FTO/TiO2/CdS bilayers was studied and compared with FTO/CdS single system. FTO/TiO2/CdS bilayers system showed improved performance of PEC properties over individual FTO/CdS thin films.

  9. Properties of bilayer contacts to porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gallach, D.; Torres-Costa, V.; Garcia-Pelayo, L.; Climent-Font, A.; Martin-Palma, R.J.; Manso, M. [Universidad Autonoma de Madrid, Departamento de Fisica Aplicada, Madrid (Spain); Barreiros-das-Santos, M.; Sporer, C.; Samitier, J. [Institute for Bioengineering of Catalonia (IBEC), Nanobioengineering Group, Barcelona (Spain)

    2012-05-15

    The aim of the present work is the growth by PVD techniques and ulterior characterization of electrical contacts to columnar porous silicon (PSi) as an approach to reliable PSi sensor devices. Contacts consist of a NiCr (40:60) and Au bilayer on the PSi surface deposited by magnetron sputtering. These structures show a good adhesion to the rough surface of columnar PSi. The morphology of these electrical contacts is characterized by electron microscopy and their crystalline structure by X-ray diffraction. Compositional profiles are determined by Rutherford backscattering spectroscopy and energy dispersive X-ray spectroscopy, which demonstrate that the infiltration of NiCr into the PSi is at the origin of the metallic thin film adhesion improvement. I-V characteristics and impedance spectroscopy measurements show that this configuration provides rectifying electrical contacts to PSi, for which a simple equivalent circuit based on one resistor and two capacitors can be modeled. These results further support the use of PSi electrical structures for sensing purposes. (orig.)

  10. Nanoscale Cross-Point Resistive Switching Memory Comprising p-Type SnO Bilayers

    KAUST Repository

    Hota, Mrinal Kanti

    2015-02-23

    Reproducible low-voltage bipolar resistive switching is reported in bilayer structures of p-type SnO films. Specifically, a bilayer homojunction comprising SnOx (oxygen-rich) and SnOy (oxygen-deficient) in nanoscale cross-point (300 × 300 nm2) architecture with self-compliance effect is demonstrated. By using two layers of SnO film, a good memory performance is obtained as compared to the individual oxide films. The memory devices show resistance ratio of 103 between the high resistance and low resistance states, and this difference can be maintained for up to 180 cycles. The devices also show good retention characteristics, where no significant degradation is observed for more than 103 s. Different charge transport mechanisms are found in both resistance states, depending on the applied voltage range and its polarity. The resistive switching is shown to originate from the oxygen ion migration and subsequent formation/rupture of conducting filaments.

  11. TiO2/WO3 photoactive bilayers in the UV-Vis light region

    Science.gov (United States)

    Vasilaki, E.; Vernardou, D.; Kenanakis, G.; Vamvakaki, M.; Katsarakis, N.

    2017-04-01

    In this work, photoactive bilayered films consisting of anatase TiO2 and monoclinic WO3 were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO3 precursor solution, when deposited as an overlying layer on TiO2 by two annealing steps ( 76% methylene blue decolorization in 300 min of irradiation versus 59% in the case of a bare TiO2 film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO2 films with WO3 acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination.

  12. Interaction of aluminum projectiles with quartz sand in impact experiments: Formation of khatyrkite (CuAl2) and reduction of SiO2 to Si

    Science.gov (United States)

    Hamann, Christopher; Stöffler, Dieter; Reimold, Wolf Uwe

    2016-11-01

    We analyzed the interaction of spherical, 6.36-mm-diameter, Cu-bearing aluminum projectiles with quartz sand targets in hypervelocity impact experiments performed at NASA Ames Vertical Gun Range. Impact velocities and inferred peak shock pressures varied between 5.9 and 6.5 km/s and ∼41 and 48 GPa, respectively. Shocked particles ("impact melt particles") coated with thin crusts of molten projectile material were recovered from the floors of the ca. 33-cm-diameter craters and the respective ejecta blankets. Through petrographic and chemical (optical microscopy, FE-EMPA, SEM-EDX, and XRF) analysis we show that these particles have a layered structure manifested in distinct layers of decreasing shock metamorphism. These can be characterized by the following physical and chemical reactions and alteration products: (i) complete melting and subsequent recrystallization of the projectile, forming a distinct crystallization texture in the fused metal crust; (ii) projectile-target mixing, involving a redox reaction between Cu-bearing Al alloy und SiO2, leading to formation of khatyrkite (CuAl2), Al2O3 melt, euhedral silicon crystals, and spherical droplets of silicon; (iii) melting of quartz to lechatelierite and formation of planar deformation features in relic quartz grains; and (iv) shock lithification of quartz grains with fracturing of grains, grain-boundary melting, planar deformation features, and complete loss of porosity. To our knowledge, this is the first report of khatyrkite formed experimentally in hypervelocity impact experiments. These results have implications for the understanding of a similar redox reaction between Al-Cu metal and siliceous impact melt recently postulated for the Khatyrka CV3 carbonaceous chondrite. Moreover, these results bear on the processes that lead to layers of regolith on the surfaces of planetary bodies without atmospheres, such as asteroids in the main belt (e.g., 4 Vesta), and on the Moon. Specifically, impacts of mm

  13. Avalanche criticalities and elastic and calorimetric anomalies of the transition from cubic Cu-Al-Ni to a mixture of 18 R and 2 H structures

    Science.gov (United States)

    Vives, Eduard; Baró, Jordi; Gallardo, María Carmen; Martín-Olalla, José-María; Romero, Francisco Javier; Driver, Sarah L.; Carpenter, Michael A.; Salje, Ekhard K. H.; Stipcich, Marcelo; Romero, Ricardo; Planes, Antoni

    2016-07-01

    We studied the two-step martensitic transition of a Cu-Al-Ni shape-memory alloy by calorimetry, acoustic emission (AE), and resonant ultrasound spectroscopy (RUS) measurements. The transition occurs under cooling from the cubic (β , F m 3 m ) parent phase near 242 K to a mixture of orthorhombic 2 H and monoclinic 18 R phases. Heating leads first to the back transformation of small 18 R domains to β and/or 2 H near 255 K, and then to the transformation 2 H to β near 280 K. The total transformation enthalpy is Δ HT=328 ±10 J/mol and is observed as one large latent heat peak under cooling. The back-transformation entropy under heating breaks down into a large component 18 R to β at 255 K and a smaller, smeared component of the transformation 2 H to β near 280 K. The proportions inside the phase mixture depend on the thermal history of the sample. The elastic response of the sample is dominated by large elastic softening during cooling. The weakening of the elastic shear modulus shows a peak at 242 K, which is typical for the formation of complex microstructures. Cooling the sample further leads to additional changes of the microstructure and domain wall freezing, which is seen by gradual elastic hardening and increasing damping of the RUS signal. Heating from 220 K to room temperature leads to elastic anomalies due to the initial transformation, which is now shifted to high temperatures. The transition is smeared over a wider temperature interval and shows strong elastic damping. The shear modulus of the cubic phase is recovered at 280 K. The phase transformation leads to avalanches, which were recorded by AE and by time-resolved calorimetry. The cooling transition shows very extended avalanche signals in calorimetry with power-law distributions. Cooling and heating runs show AE signals over a large temperature interval above 260 K. Splitting the transformation into two martensite phases leads to power-law exponents ɛ ˜2 (β ↔ 18 R ) and ɛ ˜1.5 (β ↔ 2

  14. Superdiffusion in supported lipid bilayers

    CERN Document Server

    Campagnola, Grace; Schroder, Bryce W; Peersen, Olve B; Krapf, Diego

    2015-01-01

    We study the diffusion of membrane-targeting C2 domains using single-molecule tracking in supported lipid bilayers. The ensemble-averaged mean square displacement (MSD) exhibits superdiffusive behavior. However, the time-averaged MSD of individual trajectories is found to be linear with respect to lag time, as in Brownian diffusion. These observations are explained in terms of bulk excursions that introduce jumps with a heavy-tail distribution. Our experimental results are shown to agree with analytical models of bulk-mediated diffusion and with numerical simulations.

  15. Thickness dependence of spin Hall magnetoresistance in FeMn/Pt bilayers

    Directory of Open Access Journals (Sweden)

    Yumeng Yang

    2016-06-01

    Full Text Available We investigated spin Hall magnetoresistance in FeMn/Pt bilayers, which was found to be one order of magnitude larger than that of heavy metal and insulating ferromagnet or antiferromagnet bilayer systems, and comparable to that of NiFe/Pt bilayers. The spin Hall magnetoresistance shows a non-monotonic dependence on the thicknesses of both FeMn and Pt. The former can be accounted for by the thickness dependence of net magnetization in FeMn thin films, whereas the latter is mainly due to spin accumulation and diffusion in Pt. Through analysis of the Pt thickness dependence, the spin Hall angle, spin diffusion length of Pt and the real part of spin mixing conductance were determined to be 0.2, 1.1 nm, and 5.5 × 1014 Ω−1m−2, respectively. The results corroborate the spin orbit torque effect observed in this system recently.

  16. Monolayer to Bilayer Structural Transition in Confined Pyrrolidinium-Based Ionic Liquids.

    Science.gov (United States)

    Smith, Alexander M; Lovelock, Kevin R J; Gosvami, Nitya Nand; Licence, Peter; Dolan, Andrew; Welton, Tom; Perkin, Susan

    2013-02-07

    Ionic liquids can be intricately nanostructured in the bulk and at interfaces resulting from a delicate interplay between interionic and surface forces. Here we report the structuring of a series of dialkylpyrrolidinium-based ionic liquids induced by confinement. The ionic liquids containing cations with shorter alkyl chain substituents form alternating cation-anion monolayer structures on confinement to a thin film, whereas a cation with a longer alkyl chain substituent leads to bilayer formation. The crossover from monolayer to bilayer structure occurs between chain lengths of n = 8 and 10 for these pyrrolidinium-based ionic liquids. The bilayer structure for n = 10 involves full interdigitation of the alkyl chains; this is in contrast with previous observations for imidazolium-based ionic liquids. The results are pertinent to these liquids' application as electrolytes, where the electrolyte is confined inside the pores of a nanoporous electrode, for example, in devices such as supercapacitors or batteries.

  17. Magnetic properties of the alloys system CuAl{sub 1-x}Cr{sub x}S{sub 2} (x = 0.50, 0.75); Propiedades magneticas del sistema de aleaciones CuAl{sub 1-x}Cr{sub x}S{sub 2} (x = 0.50, 0.75)

    Energy Technology Data Exchange (ETDEWEB)

    Villarreal, M. A.; Grima, P.; Quintero, M.; Moreno, E.; Fernandez, J. [Universidad de los Andes, Facultad de Ciencias, Centro de Estudios en Semiconductores, Departamento de Fisica, Apdo. de Correos No. 1, La Hechicera, 5251 Merida, (Venezuela, Bolivarian Republic of); Silva, P.; Villegas, J., E-mail: mavu@ula.ve [Instituto Venezolano de Investigaciones Cientificas, Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Carretera Panamericana Km. 11, Apdo. 21827, 1020-A Caracas (Venezuela, Bolivarian Republic of)

    2013-10-01

    The synthesis, structural characterization and magnetic properties of alloy system CuAl{sub 1-x}Cr{sub x}S{sub 2} (x = 0.50, 075) are reported. The samples were synthesized by using the direct fusion technique. The chemical analysis (EDX) confirmed the stoichiometric ratio for the concentrations. The powder diffraction patterns were indexed and the principal phases crystallizes with tetragonal symmetry with unit cell parameters a = 5.312(1) A, c = 10.389(2) A for x = 0.50 and a = 5.314(2) A, c = 10.393(2) A for x = 0.75. These alloys behave as antiferromagnetic, with Neel temperature of 37 K and 39 K, respectively. The EPR linewidth for these alloys shows a paramagnetic behavior between 100 and 610 K. The resonance field and the g factor show a slight variation with temperature. These results are discussed in terms of nearest-neighbor Cr{sup +3} (S=3/2) spin-coupled pairs. (Author)

  18. Controlled fabrication of ordered macroporous TiO2 bilayer films for the photoanode in dye-sensitized solar cells%有序大孔TiO2双层膜的设计合成及其在染料敏化太阳能电池中的应用

    Institute of Scientific and Technical Information of China (English)

    唐昭芳; 陈志刚

    2013-01-01

    以垂直沉积法制备的聚苯乙烯(polystyrene,PS)胶体晶体为模板,钛酸四异丙酯为钛源,通过浸渍-煅烧工艺制备了具有分层次有序结构的大孔TiO2双层膜,并作为光阳极应用于染料敏化太阳能电池(dye-sensitized solar cells,DSSCs).采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、紫外-可见漫反射光谱仪和氮气吸附-脱附分析仪等手段对样品进行了表征.结果表明,有序大孔TiO2薄膜较好地复制了PS模板的三维有序结构,且有较大的比表面积.光电性能测试结果表明,与以纯P25薄膜为光阳极的DSSCs相比,有序大孔TiO2双层膜为光阳极能够明显提高DSSCs的光电转换效率,可从4.16%提高到6.08%.该类型分层次有序结构大孔TiO2双层膜在DSSCs中具有重要的潜在应用价值.%Hierarchical ordered macroporous TiO2 bilayer films were successfully prepared by using 1S colloidal crystal as templates and using tetraisopropyl titanate as titanium source.We use vertical deposition method for fabrication PS colloidal crystal templates.The obtained samples were applied as the photoanode in the dye-sensitized solar cells (DSSCs) after dipping and calcination procedures.The as-synthesized products were characterized by scanning electron microscope (SEM),X-ray diffractometer (XRD),high resolution transmission electron microscope (HRTEM) and nitrogen adsorption-desorption analyzer.The results showed that the macroporous TiO2 films replicated well the three-dimensionally ordered structure derived from PS colloidal crystal templates and revealed a relatively large specific surface area.The photoelectric test results indicated that the photovoltaic conversion efficiency was improved from 4.16% to 6.08%,as compared to a device using a pure P25 TiO2 photoanode.Our results showed that the hierarchically ordered macroporous TiO2 bilayer films photoanode had important and potential applications in DSSCs.

  19. DNA nanotechnology: Bringing lipid bilayers into shape

    Science.gov (United States)

    Howorka, Stefan

    2017-07-01

    Lipid bilayers form the thin and floppy membranes that define the boundary of compartments such as cells. Now, a method to control the shape and size of bilayers using DNA nanoscaffolds has been developed. Such designer materials advance synthetic biology and could find use in membrane research.

  20. Fragmented state of lipid bilayers in water

    DEFF Research Database (Denmark)

    Helfrich, W.; Thimmel, J.; Klösgen, Beate Maria

    1999-01-01

    The bilayers of some typical biological membrane lipids such as PC and DGDG disintegrate in a large excess of water to form an optically invisible dispersive bilayer phase. `Dark bodies' can be reversibly precipitated from it by raising the temperature. The dispersive phase probably consists...

  1. Pseudocritical Behavior and Unbinding of Phospholipid Bilayers

    DEFF Research Database (Denmark)

    Lemmich, Jesper; Mortensen, Kell; Ipsen, John Hjorth;

    1995-01-01

    The temperature dependence of the small-angle neutron scattering from fully hydrated multilamellar phospholipid bilayers near the main phase transition is analyzed by means of a simple geometric model which yields both the lamellar repeat distance as well as the hydrophobic thickness of the bilayer...

  2. Alcohol's Effects on Lipid Bilayer Properties

    Science.gov (United States)

    Ingólfsson, Helgi I.; Andersen, Olaf S.

    2011-01-01

    Alcohols are known modulators of lipid bilayer properties. Their biological effects have long been attributed to their bilayer-modifying effects, but alcohols can also alter protein function through direct protein interactions. This raises the question: Do alcohol's biological actions result predominantly from direct protein-alcohol interactions or from general changes in the membrane properties? The efficacy of alcohols of various chain lengths tends to exhibit a so-called cutoff effect (i.e., increasing potency with increased chain length, which that eventually levels off). The cutoff varies depending on the assay, and numerous mechanisms have been proposed such as: limited size of the alcohol-protein interaction site, limited alcohol solubility, and a chain-length-dependent lipid bilayer-alcohol interaction. To address these issues, we determined the bilayer-modifying potency of 27 aliphatic alcohols using a gramicidin-based fluorescence assay. All of the alcohols tested (with chain lengths of 1–16 carbons) alter the bilayer properties, as sensed by a bilayer-spanning channel. The bilayer-modifying potency of the short-chain alcohols scales linearly with their bilayer partitioning; the potency tapers off at higher chain lengths, and eventually changes sign for the longest-chain alcohols, demonstrating an alcohol cutoff effect in a system that has no alcohol-binding pocket. PMID:21843475

  3. Planar bilayer membranes from photoactivable phospholipids.

    Science.gov (United States)

    Borle, F; Sänger, M; Sigrist, H

    1991-07-22

    Planar bilayer membranes formed from photoactivable phospholipids have been characterized by low frequency voltametry. Cyclic voltametric measurements were applied for simultaneous registration of planar membrane conductivity and capacitance. The procedure has been utilized to characterize the formation and stability of planar bilayer membranes. Bilayer membranes were formed from N'-(1,2-dimyristoyl-sn-glycero-3-phosphoethyl)-N-((m-3- trifluoromethyldiazirine)phenyl)thiourea (C14-PED), a head-group photosensitive phospholipid. In situ photoactivation of C14-PED at wavelengths greater than or equal to 320 nm altered neither the mean conductivity nor the capacitance of the bilayer. Ionophore (valinomycin) and ion channel (gramicidin) activities were not impaired upon photoactivation. In contrast, bilayer membranes formed from 1,2-bis(hexadeca-2,4-dienoyl)-sn- glycero-3-phosphocholine (C16-DENPC) revealed short life times. In situ photopolymerization of the diene fatty acids significantly increased the membrane conductivity or led to membrane rupture.

  4. Photon correlation spectroscopy of bilayer lipid membranes.

    Science.gov (United States)

    Crilly, J F; Earnshaw, J C

    1983-02-01

    Light scattering by thermal fluctuations on simple monoglyceride bilayer membranes has been used to investigate the viscoelastic properties of these structures. Spectroscopic analysis of these fluctuations (capillary waves) permits the nonperturbative measurement of the interfacial tension and a shear interfacial viscosity acting normal to the membrane plane. The methods were established by studies of solvent and nonsolvent bilayers of glycerol monooleate (GMO). Changes in the tension of GMO/n-decane membranes induced by altering the composition of the parent solution were detected and quantified. In a test of the reliability of the technique controlled variations of the viscosity of the aqueous bathing solution were accurately monitored. The technique was applied to solvent-free bilayers formed from dispersions of GMO in squalane. The lower tensions observed attested to the comparative absence of solvent in such bilayers. In contrast to the solvent case, the solvent-free membranes exhibited a significant transverse shear viscosity, indicative of the enhanced intermolecular interactions within the bilayer.

  5. "Nanocrystal bilayer for tandem catalysis"

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

    2011-01-24

    Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

  6. Nanocrystal bilayer for tandem catalysis.

    Science.gov (United States)

    Yamada, Yusuke; Tsung, Chia-Kuang; Huang, Wenyu; Huo, Ziyang; Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Somorjai, Gabor A; Yang, Peidong

    2011-05-01

    Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO(2)-Pt and Pt-SiO(2), can be used to catalyse two distinct sequential reactions. The CeO(2)-Pt interface catalysed methanol decomposition to produce CO and H(2), which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO(2) interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts.

  7. Multiscale Modeling of supported bilayers

    Science.gov (United States)

    Faller, Roland; Xing, Chenyue; Hoopes, Matthew I.

    2009-03-01

    Supported Lipid Bilayers are an abundant research platform for understanding the behavior of real cell membranes as they allow for additional mechanical stability. We studied systematically the changes that a support induces on a phospholipid bilayer using coarse-grained molecular modeling on different levels. We characterize the density and pressure profiles as well as the density imbalance inflicted on the membrane by the support. We also determine the diffusion coefficients and characterize the influence of different corrugations of the support. We then determine the free energy of transfer of phospholipids between the proximal and distal leaflet of a supported membrane using the coarse-grained Martini model. It turns out that there is at equilibrium about a 2-3% higher density in the proximal leaflet. These results are in favorable agreement with recent data obtained by very large scale modeling using a water free model where flip-flop can be observed directly. We compare results of the free energy of transfer obtained by pulling the lipid across the membrane in different ways. There are small quantitative differences but the overall picture is consistent. We are additionally characterizing the intermediate states which determine the barrier height and therefore the rate of translocation.

  8. Surface and grain boundary interdiffusion in nanometer-scale LSMO/BFO bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Virendra [Department of Physics, National Institute of Technology, Kurukshetra 136119 (India); Gaur, Anurag, E-mail: anuragdph@gmail.com [Department of Physics, National Institute of Technology, Kurukshetra 136119 (India); Choudhary, R.J.; Gupta, Mukul [UGC-DAE Consortium for Scientific Research, Indore 452 001 (India)

    2016-05-01

    Epitaxial 150 nm thick LSMO/BFO bilayer is deposited on STO (100) substrate by pulsed laser deposition, to study magnetoelectric effect. Unexpected low value of room temperature magnetization in bilayer indicates towards the possibility of interdiffusion. Further, sharp fall in the value of T{sub C} (53 K) also added our anxiety towards possible interdiffusion in BFO/LSMO system. Low-angle x-ray diffraction technique is used to investigate interdiffusion phenomena, and the temperature-dependent interdiffusivity is obtained by accurately monitoring the decay of the first-order modulation peak as a function of annealing time. It has been found that the diffusivity at different temperatures follows Arrhenius-type behavior. X-ray reflection (XRR) pattern obtained for the bilayer could not be fitted in the Parratt’s formalism, which confirms the interdiffusion in it. Depth profiles of {sup 209}Bi, {sup 56}Fe ions measured by secondary ion mass spectroscope (SIMS) further substantiate the diffusion of these ions from upper BFO layer into lower LSMO layer. - Highlights: • The LSMO/BFO bilayer is deposited by PLD method. • Structural, magnetic and interfacial properties of deposited films were studied. • In this article, we have raised the problem of interdiffusion in this bilayer, which can hinder its application in devices. Therefore, we feel that our article presents important finding in the area of ceramics research.

  9. Asymmetric Bilayer Muscles: Cooperative Actuation, Dynamic Hysteresis, and Creeping in NaPF6 Aqueous Solutions.

    Science.gov (United States)

    Fuchiwaki, Masaki; Martinez, Jose G; Fernandez Otero, Toribio

    2016-08-01

    Three bilayer muscles [polypyrrole-paraphenolsulfonic acid/polypyrrole-dodecylbenzensulfonic acid (PPy-HpPS/PPy-DBS) asymmetric bilayer, PPy-HpPS/tape, and PPy-DBS/tape] were characterized during potential cycling in NaPF6 aqueous solutions. In parallel, the angular displacement of the muscle was video-recorded. The dynamo-voltammetric (angle-potential) and coulo-dynamic (charge-potential) results give the reaction-driven ionic exchanges in each PPy film. Electrochemical reactions drive the exchange of anions from the PPy-HpPS layer and cations from the PPy-DBS layer. This means that both layers from the asymmetric bilayer follow complementary volume changes (swelling/shrinking or shrinking/swelling), owing to complementary ionic exchanges (entrance/expulsion) driven by the bilayer oxidation or reduction. The result is a cooperative actuation; the bending amplitude described by the asymmetric bilayer muscle is one order of magnitude larger than those attained from each of the conducting polymer/tape muscles. The cooperative actuation almost eliminates creeping effects. A large dynamical hysteresis persists, which can be attributed to an irreversible reaction of the organic acid components at high overpotentials.

  10. Possible influence of the ferromagnetic/antiferromagnetic interface on the effective critical behavior of bilayers based on La{sub 1−x}Sr{sub x}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez Miño, Lucero, E-mail: lalvarezm@unal.edu.co [Universidad Nacional de Colombia, Sede Manizales, Cra. 27 #64-60, Manizales (Colombia); Grupo de Superconductividad y Nuevos Materiales, Universidad Nacional de Colombia, Sede Bogotá, Avenida Carrera 30 #45, Bogotá (Colombia); Mulcué-Nieto, Luis Fernando, E-mail: lfmulcuen@unal.edu.co [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Cra. 27 #64-60, Manizales (Colombia)

    2015-03-01

    In this work, the effective critical exponent of the spontaneous magnetization, β, and the transition temperature, T{sub C}, were calculated from magnetization measurements of three bilayers based on La{sub 1−x}Sr{sub x}MnO{sub 3} (LSMO). The bilayers structure is a ferromagnetic (FM) LSMO film grown on top of an antiferromagnetic (AF) LSMO film. The value of the antiferromagnetic film thickness was kept the same for the three samples, while the ferromagnetic film had different thickness for each bilayer. Applying a method of calculation based on a linear superposition of the magnetization close to the critical temperature, a β value corresponding to the 3D Ising model was found for the bilayer with the thinnest ferromagnetic film. This result, and the other obtained values are explained taking into account the possible influence of the FM/AF interface on the magnetic and crystal orderings. - Highlights: • The critical exponent β of three LSMO bilayers was determined. • Two bilayers with the thinner FM layer have very similar transition temperature. • Two bilayers with the thinner FM layer have very similar width values. • We have found values of β of the 3D Ising model. • Interface also seems to be responsible for some structural disorder.

  11. Edge effects on band gap energy in bilayer 2H-MoS{sub 2} under uniaxial strain

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Wang, Jin; Dongare, Avinash M., E-mail: dongare@uconn.edu [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Namburu, Raju [Computational and Information Sciences Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States); O' Regan, Terrance P.; Dubey, Madan [Sensors and Electron Devices Directorate, U.S. Army Research Laboratory, Adelphi, Maryland 20783 (United States)

    2015-06-28

    The potential of ultrathin MoS{sub 2} nanostructures for applications in electronic and optoelectronic devices requires a fundamental understanding in their electronic structure as a function of strain. Previous experimental and theoretical studies assume that an identical strain and/or stress state is always maintained in the top and bottom layers of a bilayer MoS{sub 2} film. In this study, a bilayer MoS{sub 2} supercell is constructed differently from the prototypical unit cell in order to investigate the layer-dependent electronic band gap energy in a bilayer MoS{sub 2} film under uniaxial mechanical deformations. The supercell contains an MoS{sub 2} bottom layer and a relatively narrower top layer (nanoribbon with free edges) as a simplified model to simulate the as-grown bilayer MoS{sub 2} flakes with free edges observed experimentally. Our results show that the two layers have different band gap energies under a tensile uniaxial strain, although they remain mutually interacting by van der Waals interactions. The deviation in their band gap energies grows from 0 to 0.42 eV as the uniaxial strain increases from 0% to 6% under both uniaxial strain and stress conditions. The deviation, however, disappears if a compressive uniaxial strain is applied. These results demonstrate that tensile uniaxial strains applied to bilayer MoS{sub 2} films can result in distinct band gap energies in the bilayer structures. Such variations need to be accounted for when analyzing strain effects on electronic properties of bilayer or multilayered 2D materials using experimental methods or in continuum models.

  12. Synthesis and microstructural studies of annealed Cu(2)O/Cu(x)S bilayer as transparent electrode material for photovoltaic and energy storage devices.

    Science.gov (United States)

    Taleatu, B A; Arbab, E A A; Omotoso, E; Mola, G T

    2014-10-01

    Cu2 O thin film and a transparent bilayer have been fabricated by electrodeposition method. The growths were obtained in potentiostatic mode with gradual degradation of anodic current. X-ray diffraction (XRD) study showed that the bilayer is polycrystalline and it possesses mixture of different crystallite phases of copper oxides. Surface morphology of the films was investigated by scanning electron microscopy (SEM). The SEM images revealed that the films were uniformly distributed and the starting material (Cu2 O) had cubical structure. Grains agglomeration and crystallinity were enhanced by annealing. Optical studies indicated that all the samples have direct allowed transition. Energy band gap of the bilayer film was reduced by annealing treatment thus corroborating quantum confinement upshot. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  13. On the twinning initiation criterion in Cu-Al alpha single crystals-I. Experimental and numerical analysis of slip and dislocation patterns up to the onset of twinning

    Energy Technology Data Exchange (ETDEWEB)

    Tranchant, F.; Vergnol, J. (Univ. Poitiers, Villetaneuse (France). Lab. de Metallurgie Physique); Franciosi, P. (Univ. Paris-Nord, Villetaneuse (France). CNRS)

    1993-05-01

    Tensile tests on Cu-Al alpha single crystals oriented along the [111] axis have been performed, at room temperature, up to the twinning deformation stage on samples previously prestrained in compression along the [[bar 3]12] transversal axis. For various prestrain amplitudes, the mechanical behavior and the associated crystallographic features have been observed at both dislocation structure and slip and twin activity scales. They have then been analyzed with the help of qualitative numerical simulation obtained from a code specifically written for the single crystal plasticity and based on a dislocation description of (work) hardening.

  14. Energy Parameters of Interfacial Layers in Composite Systems: Graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and Semiconductor (Si,Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb

    Directory of Open Access Journals (Sweden)

    B.P. Koman

    2015-12-01

    Full Text Available On the basis of the non-equilibrium thermodynamics relations and the surface physics phenomena we calculate adhesion and energy parameters to characterize the interfacial interactions in graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and semiconductor (Si, Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb systems. We analyze trends of the interfacial energy, interfacial tension, work of adhesion and the energy of adhesive bonds on the contacting element’s atomic number in the periodic table and on the electronegativity difference of interacting elements. Thus, this work provides theoretical basis for the development of new composite materials.

  15. Relación estructura-propiedades en aleaciones inteligentes con memoria de forma Cu-Al-Ag de alta temperatura de transformación martensítica termoelástica

    Directory of Open Access Journals (Sweden)

    Guilemany, J. M.

    1998-05-01

    Full Text Available New shape memory alloys have been developed in the last few years with high martensitic transformation temperatures. However, the highest martensitic transformation temperatures are lower than 200°C and they are achieved with very complex alloys. New Cu-Al-Ag shape memory alloys have been developed with martensitic transformation temperatures ranging from 250 to 400°C. It is really interesting to increase the knowledge of the phase stability behaviour when cycling the alloy above or below the martensitic transformation temperature because of the high temperatures involved. Two Cu-Al-Ag shape memory alloys with very different composition have been thermal cycled in a DSC following the amount of energy release during the forward and reverse transformation and the changes of the martensitic transformation temperatures in order to follow the phase changes that takes place during cycling.

    En los últimos años, se han desarrollado nuevas aleaciones con memoria de forma, de altas temperaturas de transformación martensítica. Sin embargo, las temperaturas de transformación martensítica más elevadas son inferiores a 200°C e implican aleaciones de gran complejidad. Nuevas aleaciones con memoria de forma Cu-Al-Ag han sido desarrolladas con temperaturas de transformación entre 250 y 400°C. Es de gran importancia incrementar el conocimiento de la estabilidad de las fases durante el ciclado por encima o por debajo de la temperatura de transformación martensítica a causa de las altas temperaturas involucradas. Dos aleaciones con memoria de forma Cu-Al-Ag con muy diferente composición química han sido cicladas en el DSC midiendo la cantidad de energía liberada durante las transformaciones directa e inversa, así como los cambios en las temperaturas de transformación, con objeto de caracterizar las transformaciones de fase que tienen lugar durante el ciclado.

  16. Lipid domains control myelin basic protein adsorption and membrane interactions between model myelin lipid bilayers.

    Science.gov (United States)

    Lee, Dong Woog; Banquy, Xavier; Kristiansen, Kai; Kaufman, Yair; Boggs, Joan M; Israelachvili, Jacob N

    2014-02-25

    The surface forces apparatus and atomic force microscope were used to study the effects of lipid composition and concentrations of myelin basic protein (MBP) on the structure of model lipid bilayers, as well as the interaction forces and adhesion between them. The lipid bilayers had a lipid composition characteristic of the cytoplasmic leaflets of myelin from "normal" (healthy) and "disease-like" [experimental allergic encephalomyelitis (EAE)] animals. They showed significant differences in the adsorption mechanism of MBP. MBP adsorbs on normal bilayers to form a compact film (3-4 nm) with strong intermembrane adhesion (∼0.36 mJ/m(2)), in contrast to its formation of thicker (7-8 nm) swelled films with weaker intermembrane adhesion (∼0.13 mJ/m(2)) on EAE bilayers. MBP preferentially adsorbs to liquid-disordered submicron domains within the lipid membranes, attributed to hydrophobic attractions. These results show a direct connection between the lipid composition of membranes and membrane-protein adsorption mechanisms that affects intermembrane spacing and adhesion and has direct implications for demyelinating diseases.

  17. Modification of photosensing property of CdS–Bi{sub 2}S{sub 3} bi-layer by thermal annealing and swift heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shaikh, Shaheed U.; Siddiqui, Farha Y. [Thin Film and Nanotechnology Laboratory, Department of Physics (India); Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004 (India); Singh, Fouran; Kulriya, Pawan K. [Inter University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Phase, D.M. [UGC DAE Consortium for Scientific Research, Khandwa Road, Indore 452017 (India); Sharma, Ramphal, E-mail: ramphalsharma@yahoo.com [Thin Film and Nanotechnology Laboratory, Department of Physics (India); Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004 (India)

    2016-02-01

    The CdS–Bi{sub 2}S{sub 3} bi-layer thin films have been deposited on Indium Tin Oxide (ITO) glass substrates at room temperature by Chemical Bath Deposition Technique (CBD) and bi-layer thin films were annealed in air atmosphere for 1 h at 250 {sup °}C. The air annealed sample was irradiated using Au{sup 9+} ions at the fluence 5 × 10{sup 11} ion/cm{sup 2} with 120 MeV energy. Effects of Swift Heavy Ion (SHI) irradiation on CdS–Bi{sub 2}S{sub 3} bi-layer thin films were studied. The results are explained on the basis annealing and high electronic excitation, using X-ray diffraction (XRD), Selective Electron Area Diffraction (SEAD), Atomic Force Microscopy (AFM), Raman Spectroscopy, UV spectroscopy and I–V characteristics. The photosensing property after illumination of visible light over the samples is studied. These as-deposited, annealed and irradiated bi-layer thin films are used to sense visible light at room temperature. - Graphical abstract: Schematic illustration of CdS–Bi{sub 2}S{sub 3} bi-layer thin film (a) As-deposited (b) Annealed (c) irradiated sample respectively (d) Model of bi-layer photosensor device (e) Graph of illumination intensity verses photosensitivity. - Highlights: • CdS–Bi{sub 2}S{sub 3} bi-layer thin film prepared at room temperature. • Irradiated using Au{sup 9+} ions at the fluence of 5 × 10{sup 11} ion/cm{sup 2} with 120 MeV energy. • Study of modification induced by irradiations. • Study of Photosensitivity after annealing and irradiation.

  18. Biotechnology Applications of Tethered Lipid Bilayer Membranes

    Directory of Open Access Journals (Sweden)

    Joshua A. Jackman

    2012-12-01

    Full Text Available The importance of cell membranes in biological systems has prompted the development of model membrane platforms that recapitulate fundamental aspects of membrane biology, especially the lipid bilayer environment. Tethered lipid bilayers represent one of the most promising classes of model membranes and are based on the immobilization of a planar lipid bilayer on a solid support that enables characterization by a wide range of surface-sensitive analytical techniques. Moreover, as the result of molecular engineering inspired by biology, tethered bilayers are increasingly able to mimic fundamental properties of natural cell membranes, including fluidity, electrical sealing and hosting transmembrane proteins. At the same time, new methods have been employed to improve the durability of tethered bilayers, with shelf-lives now reaching the order of weeks and months. Taken together, the capabilities of tethered lipid bilayers have opened the door to biotechnology applications in healthcare, environmental monitoring and energy storage. In this review, several examples of such applications are presented. Beyond the particulars of each example, the focus of this review is on the emerging design and characterization strategies that made these applications possible. By drawing connections between these strategies and promising research results, future opportunities for tethered lipid bilayers within the biotechnology field are discussed.

  19. Spin dynamics of bilayer manganites

    Indian Academy of Sciences (India)

    Tapan Chatterji

    2004-07-01

    The results of inelastic and quasi-elastic neutron scattering investigations on the 40% hole-doped quasi-2D bilayer manganites La1.2Sr1.8Mn2O7 have been reviewed. The complete set of exchange interactions have been determined on the basis of a localized Heisenberg model. However, the spin wave dispersion in La1.2Sr1.8Mn2O7 shows softening close to the zone boundary and are also heavily damped especially close to the zone boundary and deviate from that expected for a simple Heisenberg model. A minimal double exchange model including quantum corrections can reproduce these effects qualitatively but falls short of quantitative agreement.

  20. Texture of lipid bilayer domains

    DEFF Research Database (Denmark)

    Jensen, Uffe Bernchou; Brewer, Jonathan R.; Midtiby, Henrik Skov

    2009-01-01

    chains. By imaging the intensity variations as a function of the polarization angle, we map the lateral variations of the lipid tilt within domains. Results reveal that gel domains are composed of subdomains with different lipid tilt directions. We have applied a Fourier decomposition method......We investigate the texture of gel (g) domains in binary lipid membranes composed of the phospholipids DPPC and DOPC. Lateral organization of lipid bilayer membranes is a topic of fundamental and biological importance. Whereas questions related to size and composition of fluid membrane domain...... are well studied, the possibility of texture in gel domains has so far not been examined. When using polarized light for two-photon excitation of the fluorescent lipid probe Laurdan, the emission intensity is highly sensitive to the angle between the polarization and the tilt orientation of lipid acyl...

  1. Bilayer-thickness-mediated interactions between integral membrane proteins

    CERN Document Server

    Kahraman, Osman; Klug, William S; Haselwandter, Christoph A

    2016-01-01

    Hydrophobic thickness mismatch between integral membrane proteins and the surrounding lipid bilayer can produce lipid bilayer thickness deformations. Experiment and theory have shown that protein-induced lipid bilayer thickness deformations can yield energetically favorable bilayer-mediated interactions between integral membrane proteins, and large-scale organization of integral membrane proteins into protein clusters in cell membranes. Within the continuum elasticity theory of membranes, the energy cost of protein-induced bilayer thickness deformations can be captured by considering compression and expansion of the bilayer hydrophobic core, membrane tension, and bilayer bending, resulting in biharmonic equilibrium equations describing the shape of lipid bilayers for a given set of bilayer-protein boundary conditions. Here we develop a combined analytic and numerical methodology for the solution of the equilibrium elastic equations associated with protein-induced lipid bilayer deformations. Our methodology al...

  2. Fragmented state of lipid bilayers in water

    DEFF Research Database (Denmark)

    Helfrich, W.; Thimmel, J.; Klösgen, Beate Maria

    1999-01-01

    The bilayers of some typical biological membrane lipids such as PC and DGDG disintegrate in a large excess of water to form an optically invisible dispersive bilayer phase. `Dark bodies' can be reversibly precipitated from it by raising the temperature. The dispersive phase probably consists...... of `knotted sticks', i.e. very thin nodular tubes of bilayer. After reviewing pertinent experimental and theoretical work we report on the discovery of a lower consolute point near room temperature in DGDG/water systems. Its existence shows that the dispersive phase and the dark bodies belong to the same...

  3. Berry phase transition in twisted bilayer graphene

    Science.gov (United States)

    Rode, Johannes C.; Smirnov, Dmitri; Schmidt, Hennrik; Haug, Rolf J.

    2016-09-01

    The electronic dispersion of a graphene bilayer is highly dependent on rotational mismatch between layers and can be further manipulated by electrical gating. This allows for an unprecedented control over electronic properties and opens up the possibility of flexible band structure engineering. Here we present novel magnetotransport data in a twisted bilayer, crossing the energetic border between decoupled monolayers and coupled bilayer. In addition a transition in Berry phase between π and 2π is observed at intermediate magnetic fields. Analysis of Fermi velocities and gate induced charge carrier densities suggests an important role of strong layer asymmetry for the observed phenomena.

  4. The action of polyene antibiotics on lipid bilayer membranes in the presence of several cations and anions

    NARCIS (Netherlands)

    Zutphen, H. van; Demel, R.A.; Norman, A.W.; Deenen, L.L.M. van

    1971-01-01

    1. 1. Filipin complex, filipin II, filipin III, nystatin, etruscomycin, and pimaricin at concentrations of 10−5 M were able to disrupt bimolecular lipid films containing lecithin and cholesterol in a 1:1 molar ratio. 2. 2. The above antibiotics were not able to disrupt lecithin bilayer

  5. Hydrophobic silver nanoparticles trapped in lipid bilayers: Size distribution, bilayer phase behavior, and optical properties

    Directory of Open Access Journals (Sweden)

    Bothun Geoffrey D

    2008-11-01

    Full Text Available Abstract Background Lipid-based dispersion of nanoparticles provides a biologically inspired route to designing therapeutic agents and a means of reducing nanoparticle toxicity. Little is currently known on how the presence of nanoparticles influences lipid vesicle stability and bilayer phase behavior. In this work, the formation of aqueous lipid/nanoparticle assemblies (LNAs consisting of hydrophobic silver-decanethiol particles (5.7 ± 1.8 nm embedded within 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC bilayers is demonstrated as a function of the DPPC/Ag nanoparticle (AgNP ratio. The effect of nanoparticle loading on the size distribution, bilayer phase behavior, and bilayer fluidity is determined. Concomitantly, the effect of bilayer incorporation on the optical properties of the AgNPs is also examined. Results The dispersions were stable at 50°C where the bilayers existed in a liquid crystalline state, but phase separated at 25°C where the bilayers were in a gel state, consistent with vesicle aggregation below the lipid melting temperature. Formation of bilayer-embedded nanoparticles was confirmed by differential scanning calorimetry and fluorescence anisotropy, where increasing nanoparticle concentration suppressed the lipid pretransition temperature, reduced the melting temperature, and disrupted gel phase bilayers. The characteristic surface plasmon resonance (SPR wavelength of the embedded nanoparticles was independent of the bilayer phase; however, the SPR absorbance was dependent on vesicle aggregation. Conclusion These results suggest that lipid bilayers can distort to accommodate large hydrophobic nanoparticles, relative to the thickness of the bilayer, and may provide insight into nanoparticle/biomembrane interactions and the design of multifunctional liposomal carriers.

  6. Development of an Automation Technique for the Establishment of Functional Lipid Bilayer Arrays

    DEFF Research Database (Denmark)

    Hansen, Jesper Søndergaard; Perry, Mark; Vogel, Jörg;

    2009-01-01

    of the lipid membranes to the formation of bilayers. The results showed that multiple lipid bilayers could be reproducible formed across the airbrush-pretreated 8 x 8 rectangular arrays. The ionophoric peptide valinomycin was incorporated into established membrane arrays, resulting in ionic currents that could......In the present work, a technique for establishing multiple black lipid membranes (BLMs) in arrays of micro structured ethylene tetrafluoroethylene (ETFE) films, and supported by a micro porous material was developed. Rectangular 8 x 8 arrays with apertures having diameters of 301 +/- 5 mu m were...... fabricated in ETFE Teflon film by laser ablation using a carbon dioxide laser. Multiple lipid membranes could be formed across the micro structured 8 x 8 array ETFE partitions. Success rates for the establishment of cellulose-supported BLMs across the multiple aperture arrays were above 95%. However...

  7. Measurements of the superconducting proximity effect in Pd/Al NS bilayers at GHz frequencies

    Science.gov (United States)

    Nersisyan, Ani; Manenti, Riccardo; Peterer, Michael; Magnusson, Einar; Tancredi, Giovanna; Patterson, Andrew; Leek, Peter

    The superconducting proximity effect, well known since the 1960s, describes superconductivity in the case of a superconductor contacted to a normal metal, and is typically studied experimentally using transport techniques such as tunneling spectroscopy. Here we will present studies of the superconducting proximity effect in thin film palladium/aluminum NS bilayers using microwave frequency lumped element LC resonators. Measurements of the resonance frequency and quality factor as a function of temperature and film thickness reveal properties of the NS bilayers such as the critical temperature and penetration depth. Our results should be useful for understanding losses in superconducting quantum circuits that incorporate thin normal layers, and, in the particular case of Pd, should aid in design of hybrid superconducting quantum devices incorporating carbon nanotubes with high contact transparency

  8. Surface Acoustic Wave Sensor with Pd/ZnO Bilayer Structure for Room Temperature Hydrogen Detection.

    Science.gov (United States)

    Viespe, Cristian; Miu, Dana

    2017-06-29

    A Surface Acoustic Wave (SAW) hydrogen sensor with a Pd/ZnO bilayer structure for room temperature sensing operation has been obtained by Pulsed Laser Deposition (PLD). The sensor structure combines a Pd layer with optimized porosity for maximizing mass effects, with the large acoustoelectric effect at the Pd/ZnO interface. The large acoustoelectric effect is due to the fact that ZnO has a surface conductivity which is highly sensitive to chemisorbed gases. The sensitivity of the sensor was determined for hydrogen concentrations between 0.2% and 2%. The limit of detection (LOD) of the bilayer sensor was about 4.5 times better than the single ZnO films and almost twice better than single Pd films.

  9. Angular dependence of demagnetization processes in Fe-FePt perpendicular exchange-spring bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Solzi, M. [Dipartimento di Fisica, Universita di Parma and CNISM, V.le G.P. Usberti 7/A, 43100 Parma (Italy)]. E-mail: solzi@fis.unipr.it; Pernechele, C. [Dipartimento di Fisica, Universita di Parma and CNISM, V.le G.P. Usberti 7/A, 43100 Parma (Italy); Pellicelli, R. [Dipartimento di Fisica, Universita di Parma and CNISM, V.le G.P. Usberti 7/A, 43100 Parma (Italy); Ghidini, M. [Dipartimento di Fisica, Universita di Parma and CNISM, V.le G.P. Usberti 7/A, 43100 Parma (Italy); Albertini, F. [IMEM-CNR, Parco Area delle Scienze 37/A, 43010 Parma (Italy); Casoli, F. [IMEM-CNR, Parco Area delle Scienze 37/A, 43010 Parma (Italy)

    2007-09-15

    The angular dependence of hysteresis loops of exchange-spring (ES) bilayers constituted by a Fe layer as the soft phase and a hard layer of L1{sub 0} Fe{sub 53}Pt{sub 47} is presented. FePt thin films of nominal thickness 10 nm have been prepared by RF sputtering on MgO (1 0 0) substrates in order to achieve the epitaxial growth with the c-axis perpendicular to the film plane. The Fe soft layers have been deposited at RT with various thicknesses (from 2 to 10 nm). The angular dependence of the bilayers' magnetic properties is studied by SQUID magnetometry varying the angle between the easy axis of the hard phase and the direction of the applied field from 0 to {pi}/2. The magnetic behavior at different angles is analyzed by a one-dimensional micromagnetic model specifically extended to the case of perpendicular magnetic anisotropy (PMA)

  10. Effect of Cu surface segregation on the exchange coupling field of NiFe/FeMn bilayers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The NiFe/FeMn bilayers with different buffer layers (Ta or Ta/Cu) were prepared by magnetron sputtering.Results show that the exchange coupling field of NiFe/FeMn films with Ta buffer is higher than that of the films with Ta/ Cu buffer. We analysed the reasons by investigating the crystallographic texture, surface roughness and surface segregation of both films, respectively. We found that the decrease of the exchange coupling fields of NiFe/FeMn films with Ta/Cu buffer layers was mainly caused by the Cu surface segregation on NiFe surface.

  11. Effect of Cryogenic Treatment on Thermal Diffusion Coefficient of Cu-Al Alloy%深冷处理对Cu-Al合金热扩散系数的影响

    Institute of Scientific and Technical Information of China (English)

    徐红

    2013-01-01

    The thermal diffusion coefficient of Cu-Al alloy before and after cryogenic treatment in the heating temperature range of 25-600 ℃ was measured by thermal constant tester.The effects of cryogenic treatment on the thermal diffusion coefficient of the alloy were investigated through comparing the variation of the thermal diffusion coefficient before and after cryogenic treatment.The results show that the variation trend of the thermal diffusion coefficient of the alloy after cryogenic treatment is the same as before,cryogenic treatment can increase the thermal diffusion coefficient of Cu-Al alloy,and the maximum difference of the thermal diffusion coefficient before and after cryogenic treatment appears at 400 ℃.%采用热常数测试仪测试了深冷处理前后Cu-Al合金在25~600℃的热扩散系数,通过对比深冷处理前后Cu-Al合金热扩散系数的变化,探讨了深冷处理对Cu-Al合金热扩散系数的影响.结果表明:深冷处理前后Cu-Al合金在25~600℃的热扩散系数变化趋势一致,深冷处理能增大Cu-Al合金热扩散系数,在400℃时,两者差值最大.

  12. 时效对铜铝钎焊接头界面化合物和性能的影响%Effects of thermal aging on intermetallic compounds and properties of Cu/Al brazing joint

    Institute of Scientific and Technical Information of China (English)

    姬峰; 薛松柏; 张满; 娄继源; 王水庆

    2012-01-01

    采用Zn-22Al钎料对铜铝异种合金进行了火焰钎焊,并用加速老化试验模拟了其服役环境.研究了时效过程中铜铝钎焊接头界面化合物的形貌变化及其对铜铝钎焊接头电阻率和抗剪强度的影响,并对其生长规律进行了初步计算.结果表明,铜侧界面化合物在250℃恒温时效过程中不断变厚,其生长规律呈抛物线状,且其生长系数约为6.1×10-13cm2/s;当界面化合物的厚度为4.2μm和18.1μm时,铜铝接头的电阻分别为120.3μΩ和132.9μΩ,该界面化合物厚度对电阻率的影响系数为0.25;铜铝接头抗剪强度在时效过程中先有3%的上升,随后逐渐降低至接头初始值的85%.%Cu/Al dissimilar metals were joined with Zn-22Al filler metal by torch-brazing technology and heat treated at constant temperature of 250 ℃ for 0 to 1000 h.To guarantee the reliability of the Cu/Al torch-brazing joints in service requirement,the growth rate of intermetallic compounds on Cu side was calculated and the effects of the intermetallic compound layer on the electrical and mechanical properties have been investigated under various annealing time.It was observed that the width of intermetallic compound increased as the thermal aging proceeded,and the growth rate of the intermetallic compound was 6.1×1013 cm2/s when the aging temperature was 250 ℃.A thicker intermetallic compound layers could degrade the resistivity and shear strength of Cu/Al joints.When the thickness of intermetallic compound was 4.2 μm and 18.1 μm,the electric resistance was 120.3 μΩ and 132.9 μΩ,respectively.Moreover,the shear strength of Cu/Al brazing joint increased by 3% when the aging time was 100 h while the strength decreased by 15% when the Cu/Al joints endured 1000 h thermal aging.

  13. Spin wave isolator based on frequency displacement nonreciprocity in ferromagnetic bilayer

    Science.gov (United States)

    Shichi, Shinsuke; Kanazawa, Naoki; Matsuda, Kenji; Okajima, Shingo; Hasegawa, Takashi; Okada, Takekazu; Goto, Taichi; Takagi, Hiroyuki; Inoue, Mitsuteru

    2015-05-01

    We demonstrated the spin wave isolator using bilayer ferromagnetic media comprising single crystalline and poly-crystalline yttrium iron garnet films, which can control the propagation frequency of magnetostatic waves by the direction of applied magnetic field. This isolator's property does not depend on their thickness then this can be downsized and integrated for nano-scale magnonic circuits. Calculated dispersion relationship shows good agreement with measured one.

  14. Spin wave isolator based on frequency displacement nonreciprocity in ferromagnetic bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Shichi, Shinsuke, E-mail: shinsuke-shichi@murata.com; Matsuda, Kenji; Okajima, Shingo; Hasegawa, Takashi; Okada, Takekazu [Murata Manufacturing Co., Ltd., Kyoto 617-8555 (Japan); Kanazawa, Naoki; Goto, Taichi, E-mail: goto@ee.tut.ac.jp; Takagi, Hiroyuki; Inoue, Mitsuteru [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibari-Ga-Oka, Tempaku, Toyohashi, Aichi 441-8580 (Japan)

    2015-05-07

    We demonstrated the spin wave isolator using bilayer ferromagnetic media comprising single crystalline and poly-crystalline yttrium iron garnet films, which can control the propagation frequency of magnetostatic waves by the direction of applied magnetic field. This isolator's property does not depend on their thickness then this can be downsized and integrated for nano-scale magnonic circuits. Calculated dispersion relationship shows good agreement with measured one.

  15. Unidirectional spin Hall magnetoresistance in ferromagnet/normal metal bilayers

    Science.gov (United States)

    Avci, Can Onur; Garello, Kevin; Ghosh, Abhijit; Gabureac, Mihai; Alvarado, Santos F.; Gambardella, Pietro

    2015-07-01

    Magnetoresistive effects are usually invariant on inversion of the magnetization direction. In non-centrosymmetric conductors, however, nonlinear resistive terms can give rise to a current dependence that is quadratic in the applied voltage and linear in the magnetization. Here we demonstrate that such conditions are realized in simple bilayer metal films where the spin-orbit interaction and spin-dependent scattering couple the current-induced spin accumulation to the electrical conductivity. We show that the longitudinal resistance of Ta|Co and Pt|Co bilayers changes when reversing the polarity of the current or the sign of the magnetization. This unidirectional magnetoresistance scales linearly with current density and has opposite sign in Ta and Pt, which we associate with the modification of the interface scattering potential induced by the spin Hall effect in these materials. Our results suggest a route to control the resistance and detect magnetization switching in spintronic devices using a two-terminal geometry, which applies also to heterostructures including topological insulators.

  16. Embedding Ba Monolayers and Bilayers in Boron Carbide Nanowires

    Science.gov (United States)

    Yu, Zhiyang; Luo, Jian; Shi, Baiou; Zhao, Jiong; Harmer, Martin P.; Zhu, Jing

    2015-11-01

    Aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) was employed to study the distribution of barium atoms on the surfaces and in the interiors of boron carbide based nanowires. Barium based dopants, which were used to control the crystal growth, adsorbed to the surfaces of the boron-rich crystals in the form of nanometer-thick surficial films (a type of surface complexion). During the crystal growth, these dopant-based surface complexions became embedded inside the single crystalline segments of fivefold boron-rich nanowires collectively, where they were converted to more ordered monolayer and bilayer modified complexions. Another form of bilayer complexion stabilized at stacking faults has also been identified. Numerous previous works suggested that dopants/impurities tended to segregate at the stacking faults or twinned boundaries. In contrast, our study revealed the previously-unrecognized possibility of incorporating dopants and impurities inside an otherwise perfect crystal without the association to any twin boundary or stacking fault. Moreover, we revealed the amount of barium dopants incorporated was non-equilibrium and far beyond the bulk solubility, which might lead to unique properties.

  17. Exchange biased anisotropic magnetoresistance in Co/CoO bilayer

    Science.gov (United States)

    Sahoo, S.; Polisetty, S.; Wang, Yi; Mukherjee, T.; He, Xi; Binek, Ch.

    2008-03-01

    We measured the anisotropic magnetoresistance of a Co(11nm)/CoO bilayer in exchange biased and unbiased states. The bilayer was fabricated on a-Al2O3 substrate maintained at 300^oC by molecular beam epitaxy at a base pressure of 10-11mbar. θ-2θ X-ray diffraction scans reveal hcp (001) texture of the Co film. No peak associated with the naturally formed CoO top layer was identified. Small angle X-ray reflectivity scans yield the Co and CoO thicknesses as 11 and 2.4nm, respectively. Exchange bias was obtained from field cooled magnetoresistance measurements at various temperatures carried out in a closed cycle cryostat. Exchange bias varies quasi linearly with temperature and vanishes at the blocking temperature, TB=97K. The latter is less than 2/3 of the bulk N'eel temperature allowing to estimate the T=0 antiferromagnetic correlation length of CoO to be 1.84 nm in accordance with the geometrical confinement.

  18. Embedding Ba Monolayers and Bilayers in Boron Carbide Nanowires.

    Science.gov (United States)

    Yu, Zhiyang; Luo, Jian; Shi, Baiou; Zhao, Jiong; Harmer, Martin P; Zhu, Jing

    2015-11-26

    Aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) was employed to study the distribution of barium atoms on the surfaces and in the interiors of boron carbide based nanowires. Barium based dopants, which were used to control the crystal growth, adsorbed to the surfaces of the boron-rich crystals in the form of nanometer-thick surficial films (a type of surface complexion). During the crystal growth, these dopant-based surface complexions became embedded inside the single crystalline segments of fivefold boron-rich nanowires collectively, where they were converted to more ordered monolayer and bilayer modified complexions. Another form of bilayer complexion stabilized at stacking faults has also been identified. Numerous previous works suggested that dopants/impurities tended to segregate at the stacking faults or twinned boundaries. In contrast, our study revealed the previously-unrecognized possibility of incorporating dopants and impurities inside an otherwise perfect crystal without the association to any twin boundary or stacking fault. Moreover, we revealed the amount of barium dopants incorporated was non-equilibrium and far beyond the bulk solubility, which might lead to unique properties.

  19. Bilayer lipid membrane (BLM) based ion selective electrodes at the meso-, micro-, and nano-scales.

    Science.gov (United States)

    Liu, Bingwen; Rieck, Daniel; Van Wie, Bernard J; Cheng, Gary J; Moffett, David F; Kidwell, David A

    2009-03-15

    This paper presents a novel method for making micron-sized apertures with tapered sidewalls and nano-sized apertures. Their use in bilayer lipid membrane-based ion selective electrode design is demonstrated and compared to mesoscale bilayers and traditional PVC ion selective electrodes. Micron-sized apertures are fabricated in SU-8 photoresist films and vary in diameter from 10 to 40 microm. The tapered edges in SU-8 films are desired to enhance bilayer lipid membrane (BLM) formation and are fabricated by UV-light overexposure. Nano-apertures are made in boron diffused silicon film. The membranes are used as septa to separate two potassium chloride solutions of different concentrations. Lecithin BLMs are assembled on the apertures by ejecting lipid solution. Potassium ionophore, dibenzo-18-crown-6, is incorporated into BLMs by dissolving it in the lipid solution before membrane assembly. Voltage changes with increasing potassium ion concentrations are recorded with an A/D converter. Various ionophore concentrations in BLMs are investigated. At least a 1% concentration is needed for consistent slopes. Electrode response curves are linear over the 10(-6) to 0.1M range with a sub-Nernstian slope of 20mV per Log concentration change. This system shows high selectivity to potassium ions over potential interfering sodium ions. BLMs on the three different aperture sizes at the meso-, micro-, and nano-scales all show similar linear ranges and limits of detection (LODs) as PVC ion selective membranes.

  20. Dynamic Morphologies of Microscale Droplet Interface Bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Mruetusatorn, Prachya [ORNL; Boreyko, Jonathan B [ORNL; Sarles, Stephen A [ORNL; Venkatesan, Guru [The University of Tennessee; Hayes, Douglas G [ORNL; Collier, Pat [ORNL

    2014-01-01

    Droplet interface bilayers (DIBs) are a powerful platform for studying the dynamics of synthetic cellular membranes; however, very little has been done to exploit the unique dynamical features of DIBs. Here, we generate microscale droplet interface bilayers ( DIBs) by bringing together femtoliter-volume water droplets in a microfluidic oil channel, and characterize morphological changes of the DIBs as the droplets shrink due to evaporation. By varying the initial conditions of the system, we identify three distinct classes of dynamic morphology. (1) Buckling and Fission: When forming DIBs using the lipid-out method (lipids in oil phase), lipids in the shrinking monolayers continually pair together and slide into the bilayer to conserve their mass. As the bilayer continues to grow, it becomes confined, buckles, and eventually fissions one or more vesicles. (2) Uniform Shrinking: When using the lipid-in method (lipids in water phase) to form DIBs, lipids uniformly transfer from the monolayers and bilayer into vesicles contained inside the water droplets. (3) Stretching and Unzipping: Finally, when the droplets are pinned to the wall(s) of the microfluidic channel, the droplets become stretched during evaporation, culminating in the unzipping of the bilayer and droplet separation. These findings offer a better understanding of the dynamics of coupled lipid interfaces.

  1. Comparison of the mechanical properties of NiTi/Cu bilayer by nanoindentation and tensile test: molecular dynamics simulation

    Science.gov (United States)

    Fazeli, Sara; Vahedpour, Morteza; Khatiboleslam Sadrnezhaad, Sayed

    2016-12-01

    Molecular dynamics simulation was used to study of mechanical properties of NiTi/Cu bilayer by nanoindentation and tensile testing. A comparison has been made among mechanical properties measured and plastic deformation process at different copper thickness during nanoindnetation and tensile test of the samples. Embedded atom method potentials for describing of inter-atomic interaction and Nose-Hoover thermostat and barostat are employed in the simulation at 400 K. The results showed that as the copper film thickness decreased, the maximum load and hardness values increased during nanoindetation. Saha and Nix model is used to describe reduced young’s modulus behaviour of the bilayer system through nanoindentation. A good agreement among calculated reduced elastic modulus by nanoindentation test and young’s modulus behaviour via tensile test have been obtained. The ‘incoherent interface’ in both of nanoindentation test and tensile testing is one of the governing factors for the dislocation propagation, which resulted in significant strengthening of the bilayer. It was observed that during tensile test, only copper layers were necked and fractured in all of samples. However, the present study seeks to examine the effect of film thickness on the free energy values that is obtained using Jarzynski’s equality during nanoindentation. As the copper film thickness was decreased, the free energy difference increased. According to both techniques, the thin film copper thickness provides lower number of nucleation locations resulting in the higher value of yield strength, hardness and free energy difference during nanoindenation. Mechanical properties of bilayer systems are improved with decreasing of copper film thickness. However, it specifies that strengths of all bilayer systems have prominent increase in young’s modulus in compared to the pure NiTi.

  2. π-Donors microstructuring on surface of polymer film by their noncovalent interactions with iodine

    Energy Technology Data Exchange (ETDEWEB)

    Traven, Valerii F., E-mail: valerii.traven@gmail.com [Mendeleev University of Chemical Technology, Moscow 125047, Miusskaya sq., 9 (Russian Federation); Ivanov, Ivan V.; Dolotov, Sergei M. [Mendeleev University of Chemical Technology, Moscow 125047, Miusskaya sq., 9 (Russian Federation); Veciana, Jaume Miro; Lebedev, Victor S. [Institut de Ciencia de Materials de Barcelona–CSIC, Campus de la UAB, 08193, Bellaterra (Spain); Shulga, Yurii M.; Khasanov, Salavat S. [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Acad. N.N. Semenov Prosp., 1, Chernogolovka, 142432 (Russian Federation); Medvedev, Michael G. [A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow 119991, Vavilova str., 28 (Russian Federation); Laukhina, Elena E. [The Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine, ICMAB-CSIC, Bellaterra, 08193 (Spain)

    2015-06-15

    Noncovalent (charge transfer) interaction between perylene and iodine in polycarbonate film provides formation of microstructured perylene layer on the polymer surface upon exposure of polymer film which contains dissolved perylene to solvent + iodine vapors. The prepared bilayer film possesses a sensing effect to iodine vapors which can be observed by both fluorescence and electrical conductivity changes. Similar bilayer films have been prepared also with anthracene and phenothiazine as π-donors with use of different polymer matrixes. Interaction of iodine with polycyclic aromatic hydrocarbons (PAH) has also been studied by the M06-2x DFT calculations for better understanding of phenomenon of π-donors microstructuring on surface of polymer film. - Highlights: • Preparation of bilayer polymer films with π-donors on surface for the first time. • π-Donor phase purity is confirmed by XRD, IR spectroscopy, SEM. • Perylene bilayer polymer films possess fluorescence. • Perylene bilayer polymer films loss fluorescence under iodine vapors. • Perylene bilayer polymer films possess electrical conductivity when treated by iodine vapors.

  3. RKKY interaction in bilayer graphene

    Science.gov (United States)

    Mohammadi, Yawar; Moradian, Rostam

    2015-12-01

    We study the RKKY interaction between two magnetic impurities located on the same layer (intralayer case) or on different layers (interlayer case) in undoped bilayer graphene (BLG) in the four-bands model, by directly calculating the Green functions in the eigenvalues and eigenvectors representation. Our results show that both intra- and interlayer RKKY interactions between two magnetic impurities located on the same (opposite) sublattice are always ferromagnetic (antiferromagnetic). Furthermore we find unusual long-distance decay of the RKKY interaction in BLG. The intralyer RKKY interactions between two magnetic impurities located on the same sublattice, J AnAn(R) and J BnBn(R), decay closely as 1 /R6 and 1 /R2 at large impurity distances respectively, but when they are located on opposite sublattices the RKKY interactions exhibit 1 /R4 decays approximately. In the interlayer case, the RKKY interactions between two magnetic impurities located on the same sublattice show a decay close to 1 /R4 at large impurity distances, but if two magnetic impurities be on opposite sublattices the RKKY interactions, J A1B2(R) and J B1A2(R), decay closely as 1 /R6 and 1 /R2 respectively. Both intra- and interlayer RKKY interactions have anisotropic oscillatory factors which for intralayer case is equal to that for single layer graphene (SLG). Our results at weak and strong interlayer coupling limits reduce to the RKKY interaction of SLG and that of BLG in the two-bands approximation respectively.

  4. PROCESS AND MECHANISM OF MICROWAVE SINTERING OF SiC-Cu/Al COMPOSITES%微波烧结SiC-Cu/Al复合材料的工艺及机理

    Institute of Scientific and Technical Information of China (English)

    王海龙; 张锐; 汪长安; 何小波; 黄勇; 胡行

    2006-01-01

    Aluminum matrix composites reinforced by silicon carbide/copper coated particles (SiC-Cu/Al) were prepared using microwave sintering. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used to characterize the sintered compacts. The process and mechanism of microwave sintering were discussed. It was found that the assistant-heating structure which was set up by mullite heat-preservation material, silicon carbide (SiC) rods and alumina crucible can effectively enhance the process of densification during sintering. The highest density of SiC-Cu/Al composites was 2.53 g/cm3 at 720 ℃. The saddle-shaped profile of the hardness with sintering temperature was detected. Correspondingly, different microstructures were observed at different temperatures. The uniformity of disturbed phases decreased with increasing temperature. Segregation of SiC grains occurred at high temperatures. Induction losses caused by both eddy currents and interfacial polarization were contributed to successful sintering.%用微波烧结工艺成功制备了铜包裹碳化硅颗粒增强铝基(SiC-Cu/Al)复合材料,利用扫描电镜和X射线衍射分析仪对烧结样品进行表征,并讨论了烧结过程及机理.研究表明:采用多晶莫来石纤维棉、硅碳棒和氧化铝坩锅组合设计的保温结构能很好地促进烧结.烧结温度为720℃时,SiC-Cu/Al复合材料的密度取得最大值为2.53g/cm3.SiC-Cu/Al复合材料的硬度随烧结温度的升高的变化成马鞍状.烧结温度对样品显微结构的影响较大,随着烧结温度的升高,相分布的均匀性降低,在较高的烧结温度下会出现SiC颗粒的偏聚.涡流损耗和界面极化损耗是促进微波烧结的主要动力.

  5. Xenon-ion-induced and thermal mixing of Co/Si bilayers and their interplay

    Science.gov (United States)

    Novaković, M.; Zhang, K.; Popović, M.; Bibić, N.; Hofsäss, H.; Lieb, K. P.

    2011-05-01

    Studies on ion-irradiated transition-metal/silicon bilayers demonstrate that interface mixing and silicide phase formation depend sensitively on the ion and film parameters, including the structure of the metal/Si interface. Thin Co layers e-gun evaporated to a thickness of 50 nm on Si(1 0 0) wafers were bombarded at room temperature with 400-keV Xe + ions at fluences of up to 3 × 10 16 cm -2. We used either crystalline or pre-amorphized Si wafers the latter ones prepared by 1.0-keV Ar-ion implantation. The as-deposited or Xe-ion-irradiated samples were then isochronally annealed at temperatures up to 700 °C. Changes of the bilayer structures induced by ion irradiation and/or annealing were investigated with RBS, XRD and HRTEM. The mixing rate for the Co/c-Si couples, Δ σ2/ Φ = 3.0(4) nm 4, is higher than the value expected for ballistic mixing and about half the value typical for spike mixing. Mixing of pre-amorphized Si is much weaker relative to crystalline Si wafers, contrary to previous results obtained for Fe/Si bilayers. Annealing of irradiated samples produces very similar interdiffusion and phase formation patterns above 400 °C as in the non-irradiated Co/Si bilayers: the phase evolution follows the sequence Co 2Si → CoSi → CoSi 2.

  6. TiO{sub 2}/WO{sub 3} photoactive bilayers in the UV-Vis light region

    Energy Technology Data Exchange (ETDEWEB)

    Vasilaki, E. [University of Crete, Department of Chemistry, Heraklion, Crete (Greece); Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Vernardou, D. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Kenanakis, G.; Katsarakis, N. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); Vamvakaki, M. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); University of Crete, Department of Materials Science and Technology, Heraklion, Crete (Greece)

    2017-04-15

    In this work, photoactive bilayered films consisting of anatase TiO{sub 2} and monoclinic WO{sub 3} were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO{sub 3} precursor solution, when deposited as an overlying layer on TiO{sub 2} by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO{sub 2} film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO{sub 2} films with WO{sub 3} acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

  7. Influence of an Fe cap layer on the structural and magnetic properties of Fe49Pt51/Fe bi-layers

    Institute of Scientific and Technical Information of China (English)

    Duan Chao-Yang; Ma Bin; Wei Fu-Lin; Zhang zong-Zhi; Jin Qing-Yuan

    2009-01-01

    The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated.Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and improve the chemical ordering of L10 FePt films. Moreover, the coercivity increases when a thin Fe layer covers the FePt layer. Beyond a critical thickness, however, the Fe cover layer quickens the magnetization reversal of Fe49Pt51/Fe bi-layers by their exchange coupling.

  8. A {sigma}-T diagram analysis regarding the {gamma}' inhibition in {beta} {r_reversible} {beta}' + {gamma}' cycling in CuAlNi single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gastien, R. [Dto. Ciencia y Tecnica de Materiales, Instituto de Investigaciones Cientificas y Tecnicas de las Fuerzas Armadas (CITEFA), J.B. de La Salle 4397, 1603 Villa Martelli, Buenos Aires (Argentina)]. E-mail: rgastien@citefa.gov.ar; Corbellani, C.E. [Dto. Ciencia y Tecnica de Materiales, Instituto de Investigaciones Cientificas y Tecnicas de las Fuerzas Armadas (CITEFA), J.B. de La Salle 4397, 1603 Villa Martelli, Buenos Aires (Argentina); Sade, M. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 S.C. de Bariloche, Rio Negro (Argentina); Lovey, F.C. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 S.C. de Bariloche, Rio Negro (Argentina)

    2006-04-15

    An effect of inhibition of the {gamma}' martensitic structure in thermal and pseudoelastic {beta} {r_reversible} {beta}' + {gamma}' cycling in CuAlNi single crystals reported previously [Gastien R, Corbellani CE, Alvarez Villar HN, Sade M, Lovey FC. Mater Sci Eng A 2003;349:191], and an experiment to determine the new thermodynamic parameters to obtain the stress-induced {gamma}' structure was performed [Gastien R, Corbellani CE, Sade M, Lovey FC. Acta Mater 2005;53:1685]. In this paper, a thermodynamic analysis of this effect using {sigma}-T diagrams is proposed, in order to obtain a proper estimation of the energy involved in the inhibition process for pseudoelastic {beta} {r_reversible} {beta}' + {gamma}' cycling.

  9. Topological fate of edge states of single Bi bilayer on Bi(111)

    Science.gov (United States)

    Yeom, Han Woong; Jin, Kyung-Hwan; Jhi, Seung-Hoon

    2016-02-01

    We address the topological nature of electronic states of step edges of Bi(111) films by first-principles band structure calculations. We confirm that the dispersion of step-edge states reflects the topological nature of underlying films, which become topologically trivial at a thickness larger than eight bilayers. This result clearly conflicts with recent claims that the step-edge state at the surface of a bulk Bi(111) crystal or a sufficiently thick Bi(111) film represents nontrivial edge states of the two-dimensional topological insulator phase expected for a very thin Bi(111) film. The trivial step-edge states have a gigantic spin splitting of one-dimensional Rashba bands and substantial intermixing with electronic states of the bulk, which might be exploited further.

  10. Piezoelectricity in asymmetrically strained bilayer graphene

    Science.gov (United States)

    Van der Donck, M.; De Beule, C.; Partoens, B.; Peeters, F. M.; Van Duppen, B.

    2016-09-01

    We study the electronic properties of commensurate faulted bilayer graphene by diagonalizing the one-particle Hamiltonian of the bilayer system in a complete basis of Bloch states of the individual graphene layers. Our novel approach is very general and can be easily extended to any commensurate graphene-based heterostructure. Here, we consider three cases: (i) twisted bilayer graphene, (ii) bilayer graphene where triaxial stress is applied to one layer and (iii) bilayer graphene where uniaxial stress is applied to one layer. We show that the resulting superstructures can be divided into distinct classes, depending on the twist angle or the magnitude of the induced strain. The different classes are distinguished from each other by the interlayer coupling mechanism, resulting in fundamentally different low-energy physics. For the cases of triaxial and uniaxial stress, the individual graphene layers tend to decouple and we find significant charge transfer between the layers. In addition, this piezoelectric effect can be tuned by applying a perpendicular electric field. Finally, we show how our approach can be generalized to multilayer systems.

  11. Residual stresses in bilayer dental ceramics.

    Science.gov (United States)

    Taskonak, Burak; Mecholsky, John J; Anusavice, Kenneth J

    2005-06-01

    It is clinically observed that lithia-disilicate-based all-ceramic fixed partial dentures (FPD) can fail because of the fragmentation of the veneering material. The hypothesis of this study is that the global residual stresses within the surface of those veneered FPDs may be responsible for partial fragmentation of the veneering ceramic. Bilayer and monolithic ceramic composites were prepared using a lithia disilicate based (Li2OSiO2) glass-ceramic core and a glass veneer. A four-step fracture mechanics approach was used to analyze residual stress in bilayered all-ceramic FPDs. We found a statistically significant increase in the mean flexural strengths of bilayer specimens compared with monolithic glass specimens (p < or = 0.05). There was a statistically significant difference between the mean longitudinal and transverse indentation-induced crack sizes in bilayer specimens (p < or = 0.05), which indicates the existence of residual stress. Global residual stresses in the veneer layer, calculated using a fracture mechanics equation, were determined to be responsible for the increased strength and observed chipping, i.e., spallation in bilayer ceramic composites.

  12. Viscoelastic deformation of lipid bilayer vesicles†

    Science.gov (United States)

    Wu, Shao-Hua; Sankhagowit, Shalene; Biswas, Roshni; Wu, Shuyang; Povinelli, Michelle L.

    2015-01-01

    Lipid bilayers form the boundaries of the cell and its organelles. Many physiological processes, such as cell movement and division, involve bending and folding of the bilayer at high curvatures. Currently, bending of the bilayer is treated as an elastic deformation, such that its stress-strain response is independent of the rate at which bending strain is applied. We present here the first direct measurement of viscoelastic response in a lipid bilayer vesicle. We used a dual-beam optical trap (DBOT) to stretch 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) giant unilamellar vesicles (GUVs). Upon application of a step optical force, the vesicle membrane deforms in two regimes: a fast, instantaneous area increase, followed by a much slower stretching to an eventual plateau deformation. From measurements of dozens of GUVs, the average time constant of the slower stretching response was 0.225 ± 0.033 s (standard deviation, SD). Increasing the fluid viscosity did not affect the observed time constant. We performed a set of experiments to rule out heating by laser absorption as a cause of the transient behavior. Thus, we demonstrate here that the bending deformation of lipid bilayer membranes should be treated as viscoelastic. PMID:26268612

  13. Viscoelastic deformation of lipid bilayer vesicles.

    Science.gov (United States)

    Wu, Shao-Hua; Sankhagowit, Shalene; Biswas, Roshni; Wu, Shuyang; Povinelli, Michelle L; Malmstadt, Noah

    2015-10-07

    Lipid bilayers form the boundaries of the cell and its organelles. Many physiological processes, such as cell movement and division, involve bending and folding of the bilayer at high curvatures. Currently, bending of the bilayer is treated as an elastic deformation, such that its stress-strain response is independent of the rate at which bending strain is applied. We present here the first direct measurement of viscoelastic response in a lipid bilayer vesicle. We used a dual-beam optical trap (DBOT) to stretch 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) giant unilamellar vesicles (GUVs). Upon application of a step optical force, the vesicle membrane deforms in two regimes: a fast, instantaneous area increase, followed by a much slower stretching to an eventual plateau deformation. From measurements of dozens of GUVs, the average time constant of the slower stretching response was 0.225 ± 0.033 s (standard deviation, SD). Increasing the fluid viscosity did not affect the observed time constant. We performed a set of experiments to rule out heating by laser absorption as a cause of the transient behavior. Thus, we demonstrate here that the bending deformation of lipid bilayer membranes should be treated as viscoelastic.

  14. Effects of substituting Ni with M (M=Cu, Al and Mn) on microstructures and electrochemical characteristics of La-Mg-Ni system (PuNi3-type) electrode alloys

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yanghuan; ZHAO Dongliang; DONG Xiaoping; REN Huiping; GUO Shihai; WANG Xinlin

    2006-01-01

    In order to improve the electrochemical cycle stability of La-Mg-Ni system (PuNi3-type) hydrogen storage alloy, Ni in the alloys was partially substituted by M (M=Cu, Al, Mn). A new La-Mg-Ni system electrode alloys La0.7Mg0.3Ni2.55-xCo0.45Mx (M=Cu, Al, Mn;x =0,0.1) were prepared by casting and rapid quenching. The effects of element substitution and rapid quenching on the microstructures and electrochemical performances of the alloys were investigated. The results by XRD, SEM and TEM show that the alloys havea multiphase structure, including the (La, Mg)Ni3 phase, the LaNi5 phase and the LaNi2 phase. The rapid quenching and element substitution have an imperceptible influence on the phase compositions of the alloys, but both change the phase abundance of the alloys. The rapid quenching significantly improves the composition homogeneity of the alloys and markedly decreases the grain size of the alloys. The Cu substitution promotes the formation of an amorphous phase in the as-quenched alloy, and a reversal result by the Al substitution. The electrochemical measurement indicates that the element substitution decreases the discharge capacity of the alloys, whereas it obviously improves the cycle stability of the alloys. The positive influence of element substitution on the cycle life of the alloys is in sequence Al>Cu>Mn, and negative influence on the discharge capacity is in sequence Al>Mn>Cu. The rapid quenching significantly enhances the cycle stability of the alloys, but it leads to a different extent decrease of thedischarge capacity of the alloys.

  15. WO{sub 3} thin film based multiple sensor array for electronic nose application

    Energy Technology Data Exchange (ETDEWEB)

    Ramgir, Niranjan S., E-mail: niranjanpr@yahoo.com, E-mail: deepakcct1991@gmail.com; Goyal, C. P.; Datta, N.; Kaur, M.; Debnath, A. K.; Aswal, D. K.; Gupta, S. K. [Thin Film Devices Section, Technical Physics Division, Bhabha Atomic Research Centre, Mumbai–400085 (India); Goyal, Deepak, E-mail: niranjanpr@yahoo.com, E-mail: deepakcct1991@gmail.com [Thin Film Devices Section, Technical Physics Division, Bhabha Atomic Research Centre, Mumbai–400085 (India); Centre for Converging Technologies, University of Rajasthan, Jaipur-302004 (India)

    2015-06-24

    Multiple sensor array comprising 16 x 2 sensing elements were realized using RF sputtered WO{sub 3} thin films. The sensor films were modified with a thin layer of sensitizers namely Au, Ni, Cu, Al, Pd, Ti, Pt. The resulting sensor array were tested for their response towards different gases namely H{sub 2}S, NH{sub 3}, NO and C{sub 2}H{sub 5}OH. The sensor response values measured from the response curves indicates that the sensor array generates a unique signature pattern (bar chart) for the gases. The sensor response values can be used to get both qualitative and quantitative information about the gas.

  16. Fabrication and characterization of vacuum evaporated Al:CuSe2 thin films

    Science.gov (United States)

    Muthukannan, Abirami; Henry, J.; Sivakumar, G.; Mohanraj, K.

    2016-01-01

    We present first report on Al doped CuSe2 thin films deposited on to the glass substrate using elemental precursors Cu, Al and Se by thermal evaporation method. The structural, morphological and optoelectronic properties of the grown films were analysed by using XRD, SEM, AFM, UV-Visible and I-V analysis respectively. The XRD study of the annealed film showed polycrystalline nature. The predominant orientation along (1 0 1) direction corresponding to orthorhombic structure of CuSe2 with an additional phase of Al2Se3 along (-3 1 4) and (3 3 1) direction. The SEM and AFM images of the annealed film bears densely packed grains and the surface roughness is found to be about 21.16 nm respectively. The direct band gap and resistivity is decreased in annealed film when compared to the as-deposited film. It could be attributed to the influence of annealing process.

  17. Possible mechanism of adhesion in a mica supported phospholipid bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Pertsin, Alexander, E-mail: ig3@ix.urz.uni-heidelberg.de [Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg (Germany); Institute of Organo-Element Compounds, Russian Academy of Sciences, Vavilov Str. 28, 117991 Moscow (Russian Federation); Grunze, Michael [Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg (Germany); Institute for Functional Interfaces, Karlsruhe Institute of Technology, Hermann-von- Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2014-05-14

    Phospholipid bilayers supported on hydrophilic solids like silica and mica play a substantial role in fundamental studies and technological applications of phospholipid membranes. In both cases the molecular mechanism of adhesion between the bilayer and the support is of primary interest. Since the possibilities of experimental methods in this specific area are rather limited, the methods of computer simulation acquire great importance. In this paper we use the grand canonical Monte Carlo technique and an atomistic force field to simulate the behavior of a mica supported phospholipid bilayer in pure water as a function of the distance between the bilayer and the support. The simulation reveals a possible adhesion mechanism, where the adhesion is due to individual lipid molecules that protrude from the bilayer and form widely spaced links with the support. Simultaneously, the bilayer remains separated from the bilayer by a thin water interlayer which maintains the bilayer fluidity.

  18. Ionic motion in PEDOT and PPy conducting polymer bilayers

    DEFF Research Database (Denmark)

    Zainudeen, Umer L.; Skaarup, Steen

    2006-01-01

    Conducting polymer bilayers with poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy), each containing dodecyl benzenesulfonate (DBS) as immobile dopant species, were synthesized galvanostatically. The electrochemical behaviour of the bilayers was investigated using cyclic voltammetry...

  19. Ionic motion in PEDOT and PPy conducting polymer bilayers

    DEFF Research Database (Denmark)

    Zainudeen, Umer L.; Skaarup, Steen

    2006-01-01

    Conducting polymer bilayers with poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy), each containing dodecyl benzenesulfonate (DBS) as immobile dopant species, were synthesized galvanostatically. The electrochemical behaviour of the bilayers was investigated using cyclic voltammetry...

  20. Interface coupling and magnetic properties of exchange-coupled Ni81Fe19/Ir22Mn78 bilayers

    CERN Document Server

    Xi, H; Mao, S; Kief, M T; White, R M

    2003-01-01

    Hysteresis loop measurements using magnetooptic Kerr effect magnetometry in the low frequency region and magnetization dynamics measurements using high frequency permeametry are carried out to study the exchange anisotropy in Ni sub 8 sub 1 Fe sub 1 sub 9 /Ir sub 2 sub 2 Mn sub 7 sub 8 bilayers. These two measurement techniques provide different exchange anisotropies for bilayers with thin Ir sub 2 sub 2 Mn sub 7 sub 8 films. The observations can be understood by assuming that the AF grains break into domains due to the interface random field. By analysing the results from these two techniques, the interface coupling strength and the magnetic properties of the bilayers can be quantitatively determined.

  1. Design of Asymmetric Peptide Bilayer Membranes.

    Science.gov (United States)

    Li, Sha; Mehta, Anil K; Sidorov, Anton N; Orlando, Thomas M; Jiang, Zhigang; Anthony, Neil R; Lynn, David G

    2016-03-16

    Energetic insights emerging from the structural characterization of peptide cross-β assemblies have enabled the design and construction of robust asymmetric bilayer peptide membranes. Two peptides differing only in their N-terminal residue, phosphotyrosine vs lysine, coassemble as stacks of antiparallel β-sheets with precisely patterned charged lattices stabilizing the bilayer leaflet interface. Either homogeneous or mixed leaflet composition is possible, and both create nanotubes with dense negative external and positive internal solvent exposed surfaces. Cross-seeding peptide solutions with a preassembled peptide nanotube seed leads to domains of different leaflet architecture within single nanotubes. Architectural control over these cross-β assemblies, both across the bilayer membrane and along the nanotube length, provides access to highly ordered asymmetric membranes for the further construction of functional mesoscale assemblies.

  2. Capacitance Variation of Electrolyte-Gated Bilayer Graphene Based Transistors

    OpenAIRE

    Hediyeh Karimi; Rubiyah Yusof; Mohammad Taghi Ahmadi; Mehdi Saeidmanesh; Meisam Rahmani; Elnaz Akbari; Wong King Kiat

    2013-01-01

    Quantum capacitance of electrolyte-gated bilayer graphene field-effect transistors is investigated in this paper. Bilayer graphene has received huge attention due to the fact that an energy gap could be opened by chemical doping or by applying external perpendicular electric field. So, this extraordinary property can be exploited to use bilayer graphene as a channel in electrolyte-gated field-effect transistors. The quantum capacitance of bi-layer graphene with an equivalent circuit is presen...

  3. Bilayer graphene quantum dot defined by topgates

    Energy Technology Data Exchange (ETDEWEB)

    Müller, André; Kaestner, Bernd; Hohls, Frank; Weimann, Thomas; Pierz, Klaus; Schumacher, Hans W., E-mail: hans.w.schumacher@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)

    2014-06-21

    We investigate the application of nanoscale topgates on exfoliated bilayer graphene to define quantum dot devices. At temperatures below 500 mK, the conductance underneath the grounded gates is suppressed, which we attribute to nearest neighbour hopping and strain-induced piezoelectric fields. The gate-layout can thus be used to define resistive regions by tuning into the corresponding temperature range. We use this method to define a quantum dot structure in bilayer graphene showing Coulomb blockade oscillations consistent with the gate layout.

  4. Temperature effect on plasmons in bilayer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Digish K., E-mail: jdiggish@gmail.com; Sharma, A. C. [Physics Department, Faculty of Science, The M.S. University of Baroda, Vadodara-390002, Gujarat (India); Ashraf, S. S. Z. [Physics Department, Faculty of Science, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh (India); Ambavale, S. K. [Vishwakarma Government Engineering College Chandkheda, Ahmedabad-382424, Gujarat (India)

    2015-06-24

    We have theoretically investigated the plasmon dispersion and damping rate of doped bilayer graphene (BLG) at finite temperatures within the random phase approximation. Our computed results on plasmon dispersion show that plasmon frequency enhances with increasing temperatures in contrast to single layer graphene where it is suppressed. This can be attributed to the fact that the dynamic response of the electron gas or screening in bilayer graphene is different from that of single layer graphene. Further the temperature effect on damping rate is also discussed.

  5. Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, Y; Imai, M [Department of Physics, Ochanomizu University, Bunkyo, Tokyo 112-8610 (Japan); Urakami, N [Department of Physics and Information Sciences, Yamaguchi University, Yamaguchi 753-8512 (Japan); Taniguchi, T, E-mail: imai@phys.ocha.ac.jp [Department of Chemical Engineering, Kyoto University, Kyoto 606-8510 (Japan)

    2011-07-20

    We have investigated the lipid sorting in a binary small unilamellar vesicle (SUV) composed of cone-shaped (1,2-dihexanoyl-sn-glycero-3-phosphocholine: DHPC) and cylinder-shaped (1,2-dipalmitoyl-sn-glycero-3-phosphocholine: DPPC) lipids. In order to reveal the lipid sorting we adopted a contrast matching technique of small angle neutron scattering (SANS), which extracts the distribution of deuterated lipids in the bilayer quantitatively without steric modification of lipids as in fluorescence probe techniques. First the SANS profile of protonated SUVs at a film contrast condition showed that SUVs have a spherical shape with an inner radius of 190 A and a bilayer thickness of 40 A. The SANS profile of deuterated SUVs at a contrast matching condition showed a characteristic scattering profile, indicating an asymmetric distribution of cone-shaped lipids in the bilayer. The characteristic profile was described well by a spherical bilayer model. The fitting revealed that most DHPC molecules are localized in the outer leaflet. Thus the shape of the lipid is strongly coupled with the membrane curvature. We compared the obtained asymmetric distribution of the cone-shaped lipids in the bilayer with the theoretical prediction based on the curvature energy model.

  6. Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique

    Science.gov (United States)

    Sakuma, Y.; Urakami, N.; Taniguchi, T.; Imai, M.

    2011-07-01

    We have investigated the lipid sorting in a binary small unilamellar vesicle (SUV) composed of cone-shaped (1,2-dihexanoyl-sn-glycero-3-phosphocholine: DHPC) and cylinder-shaped (1,2-dipalmitoyl-sn-glycero-3-phosphocholine: DPPC) lipids. In order to reveal the lipid sorting we adopted a contrast matching technique of small angle neutron scattering (SANS), which extracts the distribution of deuterated lipids in the bilayer quantitatively without steric modification of lipids as in fluorescence probe techniques. First the SANS profile of protonated SUVs at a film contrast condition showed that SUVs have a spherical shape with an inner radius of 190 Å and a bilayer thickness of 40 Å. The SANS profile of deuterated SUVs at a contrast matching condition showed a characteristic scattering profile, indicating an asymmetric distribution of cone-shaped lipids in the bilayer. The characteristic profile was described well by a spherical bilayer model. The fitting revealed that most DHPC molecules are localized in the outer leaflet. Thus the shape of the lipid is strongly coupled with the membrane curvature. We compared the obtained asymmetric distribution of the cone-shaped lipids in the bilayer with the theoretical prediction based on the curvature energy model.

  7. Homogeneous PCBM layers fabricated by horizontal-dip coating for efficient bilayer heterojunction organic photovoltaic cells.

    Science.gov (United States)

    Huh, Yoon Ho; Bae, In-Gon; Jeon, Hong Goo; Park, Byoungchoo

    2016-10-31

    We herein report a homogeneous [6,6]-phenyl C61 butyric acid methyl ester (PCBM) layer, produced by a solution process of horizontal-dipping (H-dipping) to improve the photovoltaic (PV) effects of bilayer heterojunction organic photovoltaic cells (OPVs) based on a bi-stacked poly(3-hexylthiophene) (P3HT) electron donor layer and a PCBM electron acceptor layer (P3HT/PCBM). It was shown that a homogeneous and uniform coating of PCBM layers in the P3HT/PCBM bilayer OPVs resulted in reliable and reproducible device performance. We recorded a power conversion efficiency (PCE) of 2.89%, which is higher than that (2.00%) of bilayer OPVs with a spin-coated PCBM layer. Moreover, introducing surfactant additives of poly(oxyethylene tridecyl ether) (PTE) into the homogeneous P3HT/PCBM PV layers resulted in the bilayer OPVs showing a PCE value of 3.95%, which is comparable to those of conventional bulk-heterojunction (BHJ) OPVs (3.57-4.13%) fabricated by conventional spin-coating. This improved device performance may be attributed to the selective collection of charge carriers at the interfaces among the active layers and electrodes due to the PTE additives as well as the homogeneous formation of the functional PCBM layer on the P3HT layer. Furthermore, H-dip-coated PCBM layers were deposited onto aligned P3HT layers by a rubbing technique, and the rubbed bilayer OPV exhibited improved in-plane anisotropic PV effects with PCE anisotropy as high as 1.81, which is also higher than that (1.54) of conventional rubbed BHJ OPVs. Our results suggest that the use of the H-dip-coating process in the fabrication of PCBM layers with the PTE interface-engineering additive could be of considerable interest to those seeking to improve PCBM-based opto-electrical organic thin-film devices.

  8. Bilayer characteristics of a diether phosphonolipid analog of the major lung surfactant glycerophospholipid dipalmitoyl phosphatidylcholine.

    Science.gov (United States)

    Skita, V; Chester, D W; Oliver, C J; Turcotte, J G; Notter, R H

    1995-05-01

    Thermal and lyotropic phase behavior was studied by X-ray diffraction and differential scanning calorimetry for a diether phosphonolipid analog (DEPN-8) of the major lung surfactant glycerophospholipid dipalmitoyl phosphatidylcholine (DPPC). DEPN-8 differs in an ether, rather than an ester, bond at the acyl chain-backbone linkage and a headgroup phosphonate (isosteric methylene substitution) versus phosphate constituent. Analysis of lamellar diffraction maxima demonstrated that at high relative humidity (98%) and temperatures below the liquid crystal phase transition (approximately 45 degrees C), DEPN-8 formed interdigitated bilayers with a characteristic periodicity of 41.9-46.5 A. At low humidity the gel phase DEPN-8 bilayers were characteristic of a normal L beta phase with a periodicity equivalent to DPPC (57-59 A). Above the liquid crystal thermal phase transition, bilayer spacing for both DEPN-8 and DPPC was 51-52 A, characteristic of the L alpha phase. Complete assessments of both lamellar and in-plane X-ray scattering used to construct electron density profiles and structure-factor plots for DEPN-8 defined more fully the interdigitated bilayer state at high humidity and low temperature. Compared to DPPC, it is energetically favorable for DEPN-8 to form interdigitated bilayers under conditions of excess water and low temperature. The flexible character of the ether bonds in DEPN-8 allows increased hydrophobic interactions between acyl chains, without generating a steric penalty from the increased packing density of the molecules. Additionally, the ether bond and the phosphonate moiety may allow for more energetically favorable interactions between the choline portion of the headgroup and water. The DEPN-8 ether linkage may also contribute to the improved adsorption and film respreading found previously for this phosphonolipid compared to DPPC.

  9. Catalytic effect of Al and AlN interlayer on the growth and properties of containing carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Bing, E-mail: zhoubing@tyut.edu.cn [Research institute of surface engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Zhubo; Tang, Bin [Research institute of surface engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Rogachev, A.V. [Department of Physics, Gomel State University, Gomel 246019 (Belarus)

    2015-01-30

    Highlights: • DLC and CN{sub x} bilayers with Al (AlN) interlayer were fabricated by cathode arc technique. • Complete diffusion of Al and C atoms occurs at the interface of Al/DLC (CN{sub x}) bilayer. • Al/CN{sub x} bilayer presents a higher content of Csp{sup 3}/Csp{sup 2} bonds. • The hardness of Al/DLC bilayer decreases but increases for the other bilayers. • Morphology of the bilayers was explained by growth mechanism of DLC and surface state of substrate. - Abstract: Diamond-like carbon (DLC) and carbon nitride (CN{sub x}) bilayer films with Al and AlN interlayer were fabricated by pulse cathode arc technique. The structure, composition, morphology and mechanical properties of the films were investigated by Raman, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Knoop sclerometer and surface profilometer. The results indicated that the complete diffusion between C and Al atoms occurs in the Al/DLC and Al/CN{sub x} bilayer. Al interlayer induces the increase of the size and ordering of Csp{sup 2} clusters in the films but AlN interlayer increases the disordering degree of Csp{sup 2} clusters. XPS results showed that a higher content of Csp{sup 3}/Csp{sup 2} bonds presents in the Al/CN{sub x} bilayer, and Al and AlN interlayer decreases the atomic ratio of N/C. AFM with phase contrast mode illustrated the morphologic characteristics of the bilayer films. All the bilayers show a nano-structural surface. The morphology changes of the bilayer were well explained by the surface state of the substrate and the growth mechanism of DLC films. The hardness of Al/DLC bilayer decreases but it increases for the other bilayers compared to the corresponding DLC (CN{sub x}) monolayer. The internal stress of the bilayer is significantly lower than that of the monolayer except for the AlN/CN{sub x} bilayer. These studies could make the difference at the time of choosing a suitable functional film for certain

  10. Microstructures and Recording Mechanism of Mo/Si Bilayer Applied for Write-Once Blue Laser Optical Recording

    Directory of Open Access Journals (Sweden)

    Sin-Liang Ou

    2014-01-01

    Full Text Available Mo/Si bilayer thin films were grown by magnetron sputtering and applied to write-once blu-ray disc (BD-R. The microstructures and optical storage properties of Mo/Si bilayer were investigated. From the temperature dependence of reflectivity measurement, it was revealed that a phase change occurred in the range of 255–425°C. Transmission electron microscopy analysis showed that the as-deposited film possessed Mo polycrystalline phase. The hexagonal MoSi2 and cubic Mo3Si phases appeared after annealing at 300 and 450°C, respectively. By measuring the optical reflectivity at a wavelength of 405 nm, the optical contrast of Mo/Si bilayer between as-deposited and 450°C-annealed states was evaluated to 25.8%. The optimum jitter value of 6.8% was obtained at 10.65 mW for 4× recording speed. The dynamic tests show that the Mo/Si bilayer has high potential in BD-R applications.

  11. In situ atomic force microscope imaging of supported lipid bilayers

    DEFF Research Database (Denmark)

    Kaasgaard, Thomas; Leidy, Chad; Ipsen, John Hjorth

    2001-01-01

    In situ AFM images of phospholipase A/sub 2/ (PLA/sub 2/) hydrolysis of mica-supported one- and two-component lipid bilayers are presented. For one-component DPPC bilayers an enhanced enzymatic activity is observed towards preexisting defects in the bilayer. Phase separation is observed in two......-component DMPC-DSPC bilayers and a remarkable enhanced hydrolytic activity of the PLA/sub 2/-enzyme for the DMPC-rich phase is seen. Furthermore, in a supported double bilayer system a characteristic ripple structure, most likely related to the formation of the P/sub beta /-ripple phase is observed....

  12. Electronic properties of graphene-based bilayer systems

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, A.V., E-mail: arozhkov@gmail.com [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 (Russian Federation); Sboychakov, A.O. [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Rakhmanov, A.L. [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 (Russian Federation); All-Russia Research Institute of Automatics, Moscow, 127055 (Russian Federation); Nori, Franco, E-mail: fnori@riken.jp [CEMS, RIKEN, Saitama 351-0198 (Japan); Physics Department, The University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2016-08-23

    This article reviews the theoretical and experimental work related to the electronic properties of bilayer graphene systems. Three types of bilayer stackings are discussed: the AA, AB, and twisted bilayer graphene. This review covers single-electron properties, effects of static electric and magnetic fields, bilayer-based mesoscopic systems, spin–orbit coupling, dc transport and optical response, as well as spontaneous symmetry violation and other interaction effects. The selection of the material aims to introduce the reader to the most commonly studied topics of theoretical and experimental research in bilayer graphene.

  13. Electronic properties of graphene-based bilayer systems

    Science.gov (United States)

    Rozhkov, A. V.; Sboychakov, A. O.; Rakhmanov, A. L.; Nori, Franco

    2016-08-01

    This article reviews the theoretical and experimental work related to the electronic properties of bilayer graphene systems. Three types of bilayer stackings are discussed: the AA, AB, and twisted bilayer graphene. This review covers single-electron properties, effects of static electric and magnetic fields, bilayer-based mesoscopic systems, spin-orbit coupling, dc transport and optical response, as well as spontaneous symmetry violation and other interaction effects. The selection of the material aims to introduce the reader to the most commonly studied topics of theoretical and experimental research in bilayer graphene.

  14. Electronic properties of a biased graphene bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Eduardo V; Lopes dos Santos, J M B [CFP and Departamento de Fisica, Faculdade de Ciencias Universidade do Porto, P-4169-007 Porto (Portugal); Novoselov, K S; Morozov, S V; Geim, A K [Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Peres, N M R [Centre of Physics and Departamento de Fisica, Universidade do Minho, P-4710-057 Braga (Portugal); Nilsson, Johan; Castro Neto, A H [Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, MA 02215 (United States); Guinea, F [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain)

    2010-05-05

    We study, within the tight-binding approximation, the electronic properties of a graphene bilayer in the presence of an external electric field applied perpendicular to the system-a biased bilayer. The effect of the perpendicular electric field is included through a parallel plate capacitor model, with screening correction at the Hartree level. The full tight-binding description is compared with its four-band and two-band continuum approximations, and the four-band model is shown to always be a suitable approximation for the conditions realized in experiments. The model is applied to real biased bilayer devices, made out of either SiC or exfoliated graphene, and good agreement with experimental results is found, indicating that the model is capturing the key ingredients, and that a finite gap is effectively being controlled externally. Analysis of experimental results regarding the electrical noise and cyclotron resonance further suggests that the model can be seen as a good starting point for understanding the electronic properties of graphene bilayer. Also, we study the effect of electron-hole asymmetry terms, such as the second-nearest-neighbour hopping energies t' (in-plane) and {gamma}{sub 4} (inter-layer), and the on-site energy {Delta}.

  15. Electronic properties of a biased graphene bilayer.

    Science.gov (United States)

    Castro, Eduardo V; Novoselov, K S; Morozov, S V; Peres, N M R; Lopes dos Santos, J M B; Nilsson, Johan; Guinea, F; Geim, A K; Castro Neto, A H

    2010-05-01

    We study, within the tight-binding approximation, the electronic properties of a graphene bilayer in the presence of an external electric field applied perpendicular to the system-a biased bilayer. The effect of the perpendicular electric field is included through a parallel plate capacitor model, with screening correction at the Hartree level. The full tight-binding description is compared with its four-band and two-band continuum approximations, and the four-band model is shown to always be a suitable approximation for the conditions realized in experiments. The model is applied to real biased bilayer devices, made out of either SiC or exfoliated graphene, and good agreement with experimental results is found, indicating that the model is capturing the key ingredients, and that a finite gap is effectively being controlled externally. Analysis of experimental results regarding the electrical noise and cyclotron resonance further suggests that the model can be seen as a good starting point for understanding the electronic properties of graphene bilayer. Also, we study the effect of electron-hole asymmetry terms, such as the second-nearest-neighbour hopping energies t' (in-plane) and γ(4) (inter-layer), and the on-site energy Δ.

  16. Lipid bilayer composition influences small multidrug transporters

    Directory of Open Access Journals (Sweden)

    Curnow Paul

    2008-11-01

    Full Text Available Abstract Background Membrane proteins are influenced by their surrounding lipids. We investigate the effect of bilayer composition on the membrane transport activity of two members of the small multidrug resistance family; the Escherichia coli transporter, EmrE and the Mycobacterium tuberculosis, TBsmr. In particular we address the influence of phosphatidylethanolamine and anionic lipids on the activity of these multidrug transporters. Phosphatidylethanolamine lipids are native to the membranes of both transporters and also alter the lateral pressure profile of a lipid bilayer. Lipid bilayer lateral pressures affect membrane protein insertion, folding and activity and have been shown to influence reconstitution, topology and activity of membrane transport proteins. Results Both EmrE and TBsmr are found to exhibit a similar dependence on lipid composition, with phosphatidylethanolamine increasing methyl viologen transport. Anionic lipids also increase transport for both EmrE and TBsmr, with the proteins showing a preference for their most prevalent native anionic lipid headgroup; phosphatidylglycerol for EmrE and phosphatidylinositol for TBsmr. Conclusion These findings show that the physical state of the membrane modifies drug transport and that substrate translocation is dependent on in vitro lipid composition. Multidrug transport activity seems to respond to alterations in the lateral forces exerted upon the transport proteins by the bilayer.

  17. Localized plasmons in bilayer graphene nanodisks

    DEFF Research Database (Denmark)

    Wang, Weihua; Xiao, Sanshui; Mortensen, N. Asger

    2016-01-01

    We study localized plasmonic excitations in bilayer graphene (BLG) nanodisks, comparing AA-stacked and AB-stacked BLG and contrasting the results to the case of two monolayers without electronic hybridization. The electrodynamic response of the BLG electron gas is described in terms of a spatially...

  18. Bilayer Tablet via Microsphere: A Review

    Directory of Open Access Journals (Sweden)

    Piyushkumar Vinubhai Gundaraniya

    2013-01-01

    Full Text Available The aim of the present work is to develop bilayer tablets containing sustained release microspheres as one layer and immediate release as another layer. The proposed dosage form is intended to decrease the dosing frequency and the combined administration of an anti-diabetic agent. Several pharmaceutical companies are currently developing bi-layer tablets, for a variety of reasons: patent extension, therapeutic, marketing to name a few. To reduce capital investment, quite often existing but modified tablet presses are used to develop and produce such tablets. One such approach is using microspheres as carriers for drugs also known as micro particles. It is the reliable means to deliver the drug to the target site with specificity, if modified, and to maintain the desired concentration at the site of interest. Microspheres received much attention not only for prolonged release, but also for targeting of anti-diabetic drugs. Bilayer tablet via microsphere is new era for the successful development of controlled release formulation along with various features to provide a way of successful drug delivery system. Especially when in addition high production output is required. An attempt has been made in this review article to introduce the society to the current technological developments in bilayer and floating drug delivery system.

  19. Confinement of charge carriers in bilayer graphene

    NARCIS (Netherlands)

    Goossens, A.M.

    2013-01-01

    In this thesis we investigate the fundamental properties of electronic transport in bilayer graphene. We do this by confining electrons to narrow constrictions and small islands. Our key result is the fabrication and measurement of nanoscale devices that permit confinement with electric fields in b

  20. Confinement of charge carriers in bilayer graphene

    NARCIS (Netherlands)

    Goossens, A.M.

    2013-01-01

    In this thesis we investigate the fundamental properties of electronic transport in bilayer graphene. We do this by confining electrons to narrow constrictions and small islands. Our key result is the fabrication and measurement of nanoscale devices that permit confinement with electric fields in b

  1. Quantum pumping in a ballistic graphene bilayer

    NARCIS (Netherlands)

    Wakker, G.M.M.; Blaauboer, M.

    2010-01-01

    We investigate quantum pumping of massless Dirac fermions in an ideal (impurity free) double layer of graphene. The pumped current is generated by adiabatic variation in two gate voltages in the contact regions to a weakly doped double graphene sheet. At the Dirac point and for a wide bilayer with

  2. Bright Ion Channels and Lipid Bilayers

    NARCIS (Netherlands)

    Szymanski, Wiktor; Yilmaz, Duygu; Kocer, Armagan; Feringa, Ben L.

    2013-01-01

    If we look at a simple organism such as a zebrafish under a microscope, we would see many cells working in harmony. If we zoomed in, we would observe each unit performing its own tasks in a special aqueous environment isolated from the other units by a lipid bilayer approximately 5 nm thick. These

  3. Bifurcation of self-folded polygonal bilayers

    Science.gov (United States)

    Abdullah, Arif M.; Braun, Paul V.; Hsia, K. Jimmy

    2017-09-01

    Motivated by the self-assembly of natural systems, researchers have investigated the stimulus-responsive curving of thin-shell structures, which is also known as self-folding. Self-folding strategies not only offer possibilities to realize complicated shapes but also promise actuation at small length scales. Biaxial mismatch strain driven self-folding bilayers demonstrate bifurcation of equilibrium shapes (from quasi-axisymmetric doubly curved to approximately singly curved) during their stimulus-responsive morphing behavior. Being a structurally instable, bifurcation could be used to tune the self-folding behavior, and hence, a detailed understanding of this phenomenon is appealing from both fundamental and practical perspectives. In this work, we investigated the bifurcation behavior of self-folding bilayer polygons. For the mechanistic understanding, we developed finite element models of planar bilayers (consisting of a stimulus-responsive and a passive layer of material) that transform into 3D curved configurations. Our experiments with cross-linked Polydimethylsiloxane samples that change shapes in organic solvents confirmed our model predictions. Finally, we explored a design scheme to generate gripper-like architectures by avoiding the bifurcation of stimulus-responsive bilayers. Our research contributes to the broad field of self-assembly as the findings could motivate functional devices across multiple disciplines such as robotics, artificial muscles, therapeutic cargos, and reconfigurable biomedical devices.

  4. Topological transformation of a surfactant bilayer

    DEFF Research Database (Denmark)

    Le, T.D.; Olsson, U.; Mortensen, K.

    2000-01-01

    Surfactant lamellar phases are often complicated by the formation of multilamellar (onions) under shear, which can originate simply by shaking the sample. A systematic study has been performed on the C10E3-D2O system in which different bilayer structures under a steady shear flow were investigated...

  5. Optical and electrical properties of bi-layers organic devices

    Science.gov (United States)

    Trad, Hager; Rouis, Ahlem; Davenas, Jöel; Majdoub, Mustapha

    2014-10-01

    The influence of interfacial charges on the device characteristics of bi-layers structure LEDs with poly[5-methoxy-2-octyloxy-1,4-phenylenevinylene] (MO-PPV) as active polymer layer is investigated. The concept to improve device performance is presented using: a diacetate cellulose (DAC) and a new synthetized 5-{2-(2-chloroethoxy)ethoxy}-2-{(E)-(2-pyridyl)azo}phenol (PDEG) components. The DAC and mixed (DAC+PDEG) layers were inserted between indium tin oxide (ITO) and MO-PPV polymer. The optical properties (UV-Vis) of MO-PPV, PDEG and mixed (DAC+PDEG) in solutions were studied and compared to those on thin films. Detailed current-voltage measurements of the bi-layers devices showed improvements of the threshold voltage (Vth) of the ITO/(DAC+PDEG)/MO-PPV/Al device attributed to the enhancement of carriers injection and transport resulted from the modified electrode structures. Conduction mechanisms of structure LEDs were matched with space-charge-limited current (SCLC) one. The impedance spectra for all devices can be discussed in terms of an equivalent circuit model designed as a parallel resistor Rp and capacitor Cp network in series with resistor Rs. The ITO/(DAC+PDEG)/MO-PPV/Al device showed the lowest impedance attributed to the removal of contaminants and to changes in the work function of ITO. The frequency-dependent electrical properties of the ITO/(DAC+PDEG)/MO-PPV/Al structure is analyzed by impedance spectroscopy as function of bias. We have extracted numerical values of the equivalent circuit model parameters by fitting experimental data. Their evolution with bias voltages has shown that the SCLC mechanism is characterized by an exponential trap distribution.

  6. 复合活性钎料钎焊Cu与Al2 O3的接头组织及性能%Microstructure and performance of the Cu/Al2O3 joint brazed with active composite filler

    Institute of Scientific and Technical Information of China (English)

    周英豪; 刘多; 雷玉珍; 宋晓国; 冯吉才

    2016-01-01

    为改善紫铜与Al2 O3陶瓷的连接强度,采用纳米-Al2 O3增强的AgCuTi复合钎料( AgCuTip )对紫铜与Al2 O3陶瓷进行了真空钎焊.采用扫描电镜、能谱分析以及剪切试验对钎焊接头微观组织及力学性能进行了分析.钎焊接头典型界面组织为紫铜/扩散层/铜基固溶体+银基固溶体+ Ti2 Cu + Ti3( Cu, Al)3 O/Al2 O3.纳米-Al2 O3的添加抑制了Al2 O3侧反应层的生长,并促进钎缝中形成弥散分布的Ti2Cu相.随着保温时间的延长,铜侧扩散层和Ti3(Cu, Al)3O反应层的厚度逐渐增大.保温时间为20 min时,铜母材向钎料过度溶解,降低了接头性能.当钎焊温度为880°C,保温10 min时,接头抗剪强度最高为82 MPa.纳米颗粒的加入细化了钎缝组织并降低了母材与钎缝热膨胀系数的不匹配,因此提高了接头的连接性能.保温时间可影响界面组织及反应层的厚度,进而影响接头的连接强度.%In order to improve the strength of Cu/Al2 O3 joint, vacuum brazing of copper to Al2 O3 ceramic was performed using nano -Al2O3 strengthened AgCuTi composite filler ( abbreviated as AgCuTip filler ). The microstructure and mechanical performance of the brazed joint were investigated by scanning electron microscope ( SEM ) , energy dispersive spectrometer ( EDS ) and shear strength test. Typical interfacial microstructure of Cu/AgCuTip/Al2O3 brazed joint is Cu/diffusion layer/Cu-based solid solution + Ag-based solid solution+Ti2 Cu +Ti3( Cu, Al) 3 O/Al2 O3 . The addition of nano-Al2 O3 can improve the interfacial microstructure by inhibiting the growth of reaction layer near Al2 O3 ceramic side, and promoting the formation of dispersed Ti2 Cu phase in brazing seam. Moreover, both thickness of diffusion layer and Ti3(Cu, Al)3O reaction layer thickened with an increasing holding time. Excessive dissolution of copper was occurred when holding time reached 20 min, which

  7. Overpotential deposition of Ag monolayer and bilayer on Au(1 1 1) mediated by Pb adlayer underpotential deposition/stripping cycles

    Science.gov (United States)

    Wang, J. X.; Ocko, B. M.; Adzic, R. R.

    2003-08-01

    Ultra-thin Ag films on the Au(1 1 1) surface were prepared via overpotential deposition (OPD) in the presence of Pb 2+ ions. By carrying out repetitive Pb adlayer underpotential deposition (UPD) and stripping cycles during Ag bulk deposition, the two-dimensional growth of Ag films was significantly enhanced in high OPD. The Ag monolayer sample was made by comparing the voltammetry curves, in which the signatures for Pb adlayer UPD on Au(1 1 1) changed to that on Ag(1 1 1). As demonstrated by the X-ray specular reflectivity measurements, nearly complete monolayer and bilayer films can be made with optimized deposition procedures. On subatomic scale, however, we found that these films have significant higher root-mean-square displacement amplitudes than those underpotentially deposited Ag monolayer and bilayer on either Au(1 1 1) or Pt(1 1 1).

  8. Annealing effect on the structural and magnetic properties of the CuAl{sub 0.6}Cr{sub 0.2}Fe{sub 1.2}O{sub 4} nano-ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Amer, M.A., E-mail: moazamer@hotmail.com [Physics Department, Faculty of Science, Tanta university, Tanta (Egypt); Meaz, T.M. [Physics Department, Faculty of Science, Tanta university, Tanta (Egypt); Mostafa, A.G. [ME. Lab., Physics Department, Faculty of Science, Al-Azhar University, Cairo (Egypt); El-Ghazally, H.F. [Physics Department, Faculty of Science, Tanta university, Tanta (Egypt)

    2015-07-15

    Graphical abstract: Mössbauer spectra of the as-prepared (AP) and annealed CuAl{sub 0.6}Cr{sub 0.2}Fe{sub 1.2}O{sub 4} samples. - Highlights: • As-prepared Cu–Al–Cr nano-ferrite samples were annealed at different temperatures T{sub A}. • Sample structure was transformed from cubic to tetragonal by JTE at 1000 °C. • Spontaneous and saturation magnetizations showed similar behavior against T{sub A}. • The deduced parameters showed dependence on T{sub A} and proved their affect by JTE. • Spontaneous magnetization proved dependence on crystallite size. - Abstract: Amounts of the as-synthesized CuAl{sub 0.6}Cr{sub 0.2}Fe{sub 1.2}O{sub 4} nanoparticles by the chemical co-precipitation method were annealed for 4 h at one of the temperatures T{sub A} = 300, 500, 600, 800 and 1000 °C for each. The techniques used for characterizing the samples were X-ray diffractions, infrared (IR) and Mössbauer spectroscopy and vibrating sample magnetometer. This study proved single-phase cubic structure of the samples annealed at T{sub A} ≤ 800 °C and tetragonal structure of the sample annealed at 1000 °C. The cubic-to-tetragonal structure transformation was attributed to the tetragonal distortion by Jahn–Teller effect (JTE) of Cu{sup 2+} ions. This study revealed that all deduced parameters were affected by JTE, whereas the crystallite size, lattice parameters, strain, threshold frequency, force constants, Debye temperature and stiffness constant were dependent on T{sub A}. IR absorption band positions and intensities were dependent on T{sub A} and proved the existence of Fe{sup 2+}, Fe{sup 4+} and Cr{sup 4+} ions in the crystal sublattices. The spontaneous and saturation magnetization and hyperfine magnetic field of the tetrahedral and octahedral sites were deduced and discussed as functions of T{sub A}.

  9. Influence of the technology of melting and inoculation preliminary alloy AlBe5 on change of concentration of Al and micro-structure of the bronze CuAl10Ni5Fe4

    Directory of Open Access Journals (Sweden)

    B. Pisarek

    2010-04-01

    Full Text Available Examining was the aim of the work: influence of the permanent temperature 1300°C ± 15°C and changing time of isothermal holding in the range 0÷50 minutes on the melting loss of aluminum in the bronze CuAl10Ni5Fe4; the quantity the slag rafining - covering Unitop BA-1 (0÷1,5% on the effectiveness of the protection of liquid bronze before the oxygenation, the quantity of the preliminary alloy - in-oculant AlBe5 (0÷1,0% on the effective compensation melting loss of aluminum and time of isothermal holding on the effect of the in-oculation of the bronze and the comparison of the effectiveness of the inoculation of the bronze in furnace and in the form. Introduced investigations resulted from the study of the new grades of the Cu-Al-Fe-Ni bronze with additions singly or simultaneously Si, Cr, Mo and/or W, to melting which necessary it is for high temperature and comparatively long time isothermal holding indispensable to the occur of the process of diffusive dissolving the high-melting of the bronze components. High temperature and lengthening the time of isothermal holding the liquid bronze in casting furnace the melting loss of Al influences the growth. Addition the slag of covering-refining Unitop BA-1 in the quantity 1,5% the bronze protects before the melting loss of aluminum by the time of isothermal holding in the temperature 1300°C about 15 minutes. Addition of the preliminary alloy AlBe5 in the quantity 0,6% it assures the effective compensation of the aluminum which melting loss undergoes for the studied parameters of the melting. The effect of the inoculation of the bronze together with diminishes the preliminary alloy AlBe5 with lengthening the time of isothermal hold-ing. Because of this, use of the method of introducing the preliminary alloy it is seems good solution on the inoculation of aluminum bronzes directly to form, unsensitive on the time of isothermal holding the bronze.

  10. High performance ceria-bismuth bilayer electrolyte low temperature solid oxide fuel cells (LT-SOFCs) fabricated by combining co-pressing with drop-coating

    KAUST Repository

    Hou, Jie

    2015-03-24

    The Sm0.075Nd0.075Ce0.85O2-δ-Er0.4Bi1.6O3 bilayer structure film, which showed an encouraging performance in LT-SOFCs, was successfully fabricated by a simple low cost technique combining one-step co-pressing with drop-coating.

  11. Chiral atomically thin films

    Science.gov (United States)

    Kim, Cheol-Joo; Sánchez-Castillo, A.; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm-1) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  12. Molecular phospholipid films on solid supports

    DEFF Research Database (Denmark)

    Czolkos, Ilja; Jesorka, Aldo; Orwar, Owe

    2011-01-01

    Phospholipid membranes are versatile structures for mimicking biological surfaces. Bilayer and monolayer membranes can be formed on solid supports, leading to enhanced stability and accessibility of the biomimetic molecular film. This has facilitated functional studies of membrane proteins...... stable lipid membranes. In this review, the current state of the art of molecularly thin lipid layer fabrication is presented with an emphasis on support materials, film formation mechanisms, characterisation methods, and applications....

  13. Multiscale Modeling of Supported Lipid Bilayers

    Science.gov (United States)

    Hoopes, Matthew I.; Xing, Chenyue; Faller, Roland

    Cell membranes consist of a multitude of lipid molecules that serve as a framework for the even greater variety of membrane associated proteins [1-4]. As this highly complex (nonequilibrium) system cannot easily be understood and studied in a controlled way, a wide variety of model systems have been devised to understand the dynamics, structure, and thermodynamics in biological membranes. One such model system is a supported lipid bilayer (SLB), a two-dimensional membrane suspended on a surface. SLBs have been realized to be manageable experimentally while reproducing many of the key features of real biological membranes [5,6]. One of the main advantages of supported bilayers is the physical stability due to the solid support that enables a wide range of surface characterization techniques not available to free or unsupported membranes. As SLBs maintain some of the crucial structural and dynamic properties of biological membranes, they provide an important bridge to natural systems. In order to mimic cell membranes reliably, certain structural and dynamic features have to be reliably reproduced in the artificially constructed lipid bilayers. SLBs should display lateral mobility as in living cells, because many membrane activities involve transport, recruitment, or assembly of specific components. It is also critical for membranes to exhibit the correct thermodynamic phase, namely, a fluid lipid bilayer, to respond to environmental stress such as temperature and pressure changes [7]. There are several ways to fabricate supported lipid bilayers (SLBs) on planar substrates. One can use vesicle fusion on solid substrates [5,8-10] as well as Langmuir-Blodgett deposition [11,12]. Proteoliposome adsorption and subsequent membrane formation on a mica surface was first demonstrated by Brian and McConnell [13]. Because of its simplicity and reproducibility, this is one of the most common approaches to prepare supported membranes. A diverse range of different solid substrates

  14. Titanium dioxide-coated fluorine-doped tin oxide thin films for improving overall photoelectric property

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bao-jia, E-mail: bjia_li@126.com [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); Huang, Li-jing [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); Ren, Nai-fei [Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Zhou, Ming [The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2014-01-30

    Titanium (Ti) layers were deposited by direct current (DC) magnetron sputtering on commercial fluorine-doped tin oxide (FTO) glasses, followed by simultaneous oxidation and annealing treatment in a tubular furnace to prepare titanium dioxide (TiO{sub 2})/FTO bilayer films. Large and densely arranged grains were observed on all TiO{sub 2}/FTO bilayer films. The presence of TiO{sub 2} tetragonal rutile phase in the TiO{sub 2}/FTO bilayer films was confirmed by X-ray diffraction (XRD) analysis. The results of parameter optimization indicated that the TiO{sub 2}/FTO bilayer film, which was formed by adopting a temperature of 400 °C and an oxygen flow rate of 15 sccm, had the optimal overall photoelectric property with a figure of merit of 2.30 × 10{sup −2} Ω{sup −1}, higher than 1.78 × 10{sup −2} Ω{sup −1} for the FTO single-layer film. After coating a 500 nm-thick AZO layer by DC magnetron sputtering on this TiO{sub 2}/FTO bilayer film, the figure of merit of the trilayer film achieved to a higher figure of merit of 3.12 × 10{sup −2} Ω{sup −1}, indicating further improvement of the overall photoelectric property. This work may provide a scientific basis and reference for improving overall photoelectric property of transparent conducting oxide (TCO) films.

  15. Exchange-bias field induced by surface inhomogeneities in ferromagnetic/charge-ordered bilayer structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haiou, E-mail: wanghaiou@hdu.edu.cn [Institute of Materials Physics, Hangzhou Dianzi University, Hangzhou, 310018 (China); Key Laboratory of Soft Chemistry and Functional Materials, Ministry of Education, Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, 210094 (China); Yang, Weifeng; Su, Kunpeng [Institute of Materials Physics, Hangzhou Dianzi University, Hangzhou, 310018 (China); Huo, Dexuan, E-mail: dxhuo@hdu.edu.cn [Institute of Materials Physics, Hangzhou Dianzi University, Hangzhou, 310018 (China); Tan, Weishi [Key Laboratory of Soft Chemistry and Functional Materials, Ministry of Education, Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, 210094 (China)

    2015-11-05

    Epitaxial bilayer structure consisting of ferromagnetic metallic Pr{sub 0.7}Sr{sub 0.3}MnO{sub 3} (PSMO) and charge-ordered insulator La{sub 0.5}Ca{sub 0.5}MnO{sub 3} (LCMO) was fabricated on (001) SrTiO{sub 3} substrate by pulsed laser deposition. High-resolution synchrotron X-ray diffraction showed high quality of epitaxial layer. However, besides diffraction peaks from PSMO layer, LCMO layer and SrTiO{sub 3} substrate, we observed an additional shoulder peak, which might stem from the inhomogeneities of composition in PSMO/LCMO. Further the atomic force microscopy measurement showed the presence of non-stoichiometric large particulates at surface, imparting an overall inhomogeneous composition to the film. This implied that the variation of crystalline structure of PSMO/LCMO occurred due to inhomogeneous composition. Moreover, studies on magnetic properties showed that surface inhomogeneities and ferromagnetic clusters at the PSMO/LCMO interface probably influenced the ferromagnetism of the bilayer film together, tuning exchange bias effect. - Highlights: • We report the epitaxial growth of Pr{sub 0.7}Sr{sub 0.3}MnO{sub 3}/La{sub 0.5}Ca{sub 0.5}MnO{sub 3} bilayer on SrTiO{sub 3}. • The non-stoichiometric particulates at surface impart inhomogeneous composition. • Inhomogeneities in the film lead to the variation of crystalline structure. • Surface inhomogeneities reduce ferromagnetism and enhance exchange bias effect.

  16. Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, an