WorldWideScience

Sample records for sacrificial layer materials

  1. SU-8 Based MEMS Process with Two Metal Layers using ?-Si as a Sacrificial Material

    KAUST Repository

    Ramadan, Khaled S.

    2012-04-01

    Polymer based microelectromechanical systems (MEMS) micromachining is finding more interest in research and applications. This is due to its low cost and less time processing compared with silicon MEMS. SU-8 is a photo-patternable polymer that is used as a structural layer for MEMS and microfluidic devices. In addition to being processed with low cost, it is a biocompatible material with good mechanical properties. Also, amorphous silicon (?-Si) has found use as a sacrificial layer in silicon MEMS applications. ?-Si can be deposited at large thicknesses for MEMS applications and also can be released in a dry method using XeF2 which can solve stiction problems related to MEMS applications. In this thesis, an SU-8 MEMS process is developed using amorphous silicon (?-Si) as a sacrificial layer. Electrostatic actuation and sensing is used in many MEMS applications. SU-8 is a dielectric material which limits its direct use in electrostatic actuation. This thesis provides a MEMS process with two conductive metal electrodes that can be used for out-of-plane electrostatic applications like MEMS switches and variable capacitors. The process provides the fabrication of dimples that can be conductive or non-conductive to facilitate more flexibility for MEMS designers. This SU-8 process can fabricate SU-8 MEMS structures of a single layer of two different thicknesses. Process parameters were tuned for two sets of thicknesses which are thin (5-10?m) and thick (130?m). Chevron bent-beam structures and different suspended beams (cantilevers and bridges) were fabricated to characterize the SU-8 process through extracting the density, Young’s Modulus and the Coefficient of Thermal Expansion (CTE) of SU-8. Also, the process was tested and used as an educational tool through which different MEMS structures were fabricated including MEMS switches, variable capacitors and thermal actuators.

  2. Fabrication of polyimide sacrificial layers with inclined sidewalls based on reactive ion etching

    OpenAIRE

    Yuanjing Chen; Haiyang Mao; Qiulin Tan; Chenyang Xue; Wen Ou; Jin Liu; Dapeng Chen

    2014-01-01

    Polyimide is used as a sacrificial material because of its low stress, its removable ability and its compatibility with standard micromachining processes. In this work, polyimide structures with inclined sidewalls are fabricated with a reactive ion etching process, where SiO2 is used as the hard-mask material. The structures can be further used as sacrificial layers in micro-electro-mechanical systems infrared (IR) sensors to support IR absorbers, to realize the thermal connections between th...

  3. Methods of producing free-standing semiconductors using sacrificial buffer layers and recyclable substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ptak, Aaron Joseph; Lin, Yong; Norman, Andrew; Alberi, Kirstin

    2015-05-26

    A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a spinel substrate using a sacrificial buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The sacrificial buffer material and semiconductor materials may be deposited using lattice-matching epitaxy or coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The sacrificial buffer layer may be dissolved using an epitaxial liftoff technique in order to separate the semiconductor device from the spinel substrate, and the spinel substrate may be reused in the subsequent fabrication of other semiconductor devices. The low-defect density semiconductor materials produced using this method result in the enhanced performance of the semiconductor devices that incorporate the semiconductor materials.

  4. PostCMOS compatible sacrificial layers for aluminum nitride microcantilevers

    Science.gov (United States)

    Pérez-Campos, Ana; Iriarte, Gonzalo Fuentes; Lebedev, Vadim; Calle, Fernando

    2014-10-01

    This report shows different fabrication procedures followed to obtain piezoelectric microcantilevers. The proposed microcantilever is a sandwich structure composed of chromium (Cr) electrodes (from 50 to 300-nm thick) and a reactive sputtered piezoelectric aluminum nitride (AlN) thin film (from 350 nm to 600-nm thick). The microcantilevers top-view dimensions ranged from 50 to 300 ?m in width and from to 250 to 700 ?m in length. Several materials such as nickel silicide and nickel, as well as a photoresist, and finally the silicon substrate surface have been investigated to discern their possibilities and limitations when used as sacrificial layers. These materials have been studied to determine the optimal processing steps and chemistries required for each of them. The easiest and the only successful microcantilevers release was finally obtained using the top silicon substrate surface as a sacrificial layer. The structural and morphological characteristics of the microcantilevers are presented as well as their piezoelectric character. The main difference of this work resides in the Si surface-based microcantilever release technique. This, along with the synthesis of AlN at room temperature by reactive sputtering, establishes a manufacturing procedure for piezoelectric microbeams, which makes possible the integration of such MEMS devices into postCMOS technology.

  5. Performance characterization of geopolymer composites for hot sodium exposed sacrificial layer in fast breeder reactors

    International Nuclear Information System (INIS)

    Highlights: • Performance evaluation of geopolymers subjected to hot liquid sodium is performed. • Apart from mechanical properties, micro-analytical techniques are used for material characterization. • The geopolymer composite showed comparatively lesser damage than conventional cement composites. • Geopolymer technology can emerge as a new choice for sacrificial layer in SCFBRs. - Abstract: A sacrificial layer of concrete is used in sodium cooled fast breeder reactors (SCFBRs) to mitigate thermo-chemical effect of accidentally spilled sodium at and above 550 °C on structural concrete. Performance of this layer is governed by thermo-chemical stability of the ingredients of sacrificial layer concrete. Concrete with limestone aggregate is generally used as a sacrificial layer. Conventional cement based systems exhibit instability in hot liquid sodium environment. Geo-polymer composites are well known to perform excellently at elevated temperatures compared to conventional cement systems. This paper discusses performance of such composites subjected to exposure of hot liquid sodium in air. The investigation includes comprehensive evaluation of various geo-polymer composites before any exposure, after heating to 550 °C in air, and after immersing in hot liquid sodium initially heated to 550 °C in air. Results from the current study indicate that hot liquid sodium produces less damage to geopolymer composites than to the existing conventional cement based system. Hence, the geopolymer technology has potential application in mitigating the degrading effects of sodium fires and can emerge as a new choice for sodium exposed sacrificial layer in SCFBRs

  6. Performance characterization of geopolymer composites for hot sodium exposed sacrificial layer in fast breeder reactors

    Energy Technology Data Exchange (ETDEWEB)

    Haneefa, K. Mohammed, E-mail: mhkolakkadan@gmail.com [Department of Civil Engineering, IIT Madras, Chennai (India); Santhanam, Manu [Department of Civil Engineering, IIT Madras, Chennai (India); Parida, F.C. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2013-12-15

    Highlights: • Performance evaluation of geopolymers subjected to hot liquid sodium is performed. • Apart from mechanical properties, micro-analytical techniques are used for material characterization. • The geopolymer composite showed comparatively lesser damage than conventional cement composites. • Geopolymer technology can emerge as a new choice for sacrificial layer in SCFBRs. - Abstract: A sacrificial layer of concrete is used in sodium cooled fast breeder reactors (SCFBRs) to mitigate thermo-chemical effect of accidentally spilled sodium at and above 550 °C on structural concrete. Performance of this layer is governed by thermo-chemical stability of the ingredients of sacrificial layer concrete. Concrete with limestone aggregate is generally used as a sacrificial layer. Conventional cement based systems exhibit instability in hot liquid sodium environment. Geo-polymer composites are well known to perform excellently at elevated temperatures compared to conventional cement systems. This paper discusses performance of such composites subjected to exposure of hot liquid sodium in air. The investigation includes comprehensive evaluation of various geo-polymer composites before any exposure, after heating to 550 °C in air, and after immersing in hot liquid sodium initially heated to 550 °C in air. Results from the current study indicate that hot liquid sodium produces less damage to geopolymer composites than to the existing conventional cement based system. Hence, the geopolymer technology has potential application in mitigating the degrading effects of sodium fires and can emerge as a new choice for sodium exposed sacrificial layer in SCFBRs.

  7. Use of silicon oxynitride as a sacrificial material for microelectromechanical devices

    Science.gov (United States)

    Habermehl, Scott D. (Corrales, NM); Sniegowski, Jeffry J. (Edgewood, NM)

    2001-01-01

    The use of silicon oxynitride (SiO.sub.x N.sub.y) as a sacrificial material for forming a microelectromechanical (MEM) device is disclosed. Whereas conventional sacrificial materials such as silicon dioxide and silicate glasses are compressively strained, the composition of silicon oxynitride can be selected to be either tensile-strained or substantially-stress-free. Thus, silicon oxynitride can be used in combination with conventional sacrificial materials to limit an accumulation of compressive stress in a MEM device; or alternately the MEM device can be formed entirely with silicon oxynitride. Advantages to be gained from the use of silicon oxynitride as a sacrificial material for a MEM device include the formation of polysilicon members that are substantially free from residual stress, thereby improving the reliability of the MEM device; an ability to form the MEM device with a higher degree of complexity and more layers of structural polysilicon than would be possible using conventional compressively-strained sacrificial materials; and improved manufacturability resulting from the elimination of wafer distortion that can arise from an excess of accumulated stress in conventional sacrificial materials. The present invention is useful for forming many different types of MEM devices including accelerometers, sensors, motors, switches, coded locks, and flow-control devices, with or without integrated electronic circuitry.

  8. Formulation and processing of screen-printing vehicles for sacrificial layers on thick-film and LTCC substrates

    OpenAIRE

    Maeder, Thomas; Jacq, Caroline; Fournier, Yannick; Ryser, Peter

    2008-01-01

    Ceramic technologies such as thick-film and LTCC (Low Temperature Cofired Ceramic) are excellent platforms for the fabrication of mesoscale devices such as sensors, actuators, microreactors and MEMS packaging. This work presents two alternative screen-printing vehicles for the processing of sacrificial materials and low-firing thick films: 1) a non-aggressive glycol-based vehicle for screen printing thick sacrificial layers onto thin LTCC, and 2) a "high non-evaporables" vehicle for mineral /...

  9. Fabrication of polyimide sacrificial layers with inclined sidewalls based on reactive ion etching

    Directory of Open Access Journals (Sweden)

    Yuanjing Chen

    2014-03-01

    Full Text Available Polyimide is used as a sacrificial material because of its low stress, its removable ability and its compatibility with standard micromachining processes. In this work, polyimide structures with inclined sidewalls are fabricated with a reactive ion etching process, where SiO2 is used as the hard-mask material. The structures can be further used as sacrificial layers in micro-electro-mechanical systems infrared (IR sensors to support IR absorbers, to realize the thermal connections between the absorbers and the thermopiles, and to scale down the size of the sensors. As a result, IR sensors with low-residual-stress absorption, high structural stability, low heat loss and small dimensions can be achieved.

  10. Fabrication of polyimide sacrificial layers with inclined sidewalls based on reactive ion etching

    Science.gov (United States)

    Chen, Yuanjing; Mao, Haiyang; Tan, Qiulin; Xue, Chenyang; Ou, Wen; Liu, Jin; Chen, Dapeng

    2014-03-01

    Polyimide is used as a sacrificial material because of its low stress, its removable ability and its compatibility with standard micromachining processes. In this work, polyimide structures with inclined sidewalls are fabricated with a reactive ion etching process, where SiO2 is used as the hard-mask material. The structures can be further used as sacrificial layers in micro-electro-mechanical systems infrared (IR) sensors to support IR absorbers, to realize the thermal connections between the absorbers and the thermopiles, and to scale down the size of the sensors. As a result, IR sensors with low-residual-stress absorption, high structural stability, low heat loss and small dimensions can be achieved.

  11. Structuration of zero-shrinkage LTCC using mineral sacrificial materials

    OpenAIRE

    Maeder, Thomas; Jacq, Caroline; Fournier, Yannick; Hraiz, Wassim; Ryser, Peter

    2009-01-01

    Recently, LTCC (low-temperature co-fired ceramic) technology has increasingly found applications beyond pure electronics, in fields such as microfluidics, sensors and actuators, due to the ease of shaping the tapes in the green (unfired) state. Accurate control of hollow structures such as channels, membranes, cavities and gaps below cantilevers has remained difficult, however, although carbon-based sacrificial materials and adhesive/solvent-assisted low-pressure lamination techni...

  12. A novel method for sacrificial layer release in MEMS devices fabrication

    International Nuclear Information System (INIS)

    During the forming process of the free-standing structure or the functional cavity when releasing the high aspect ratio sacrificial layer, such structures tend to stick to the substrate due to capillary force. This paper describes the application of pull-in length conception as design rules to a novel 'dimpled' method in releasing sacrificial layer. Based on the conception of pull-in length in adhering phenomenon, the fabrication and releasing sacrificial layer methods using micro bumps based on the silicon substrate were presented. According to the thermal isolation performances of one kind of micro electromechanical system device thermal shear stress sensor, the sacrificial layers were validated to be successfully released. (condensed matter: structure, thermal and mechanical properties)

  13. New sacrificial material for ex-vessel core catcher

    Science.gov (United States)

    Komlev, Andrei A.; Almjashev, Vyacheslav I.; Bechta, Sevostian V.; Khabensky, Vladimir B.; Granovsky, Vladimir S.; Gusarov, Victor V.

    2015-12-01

    A new functional (sacrificial) material has been developed in the Fe2O3-SrO-Al2O3-CaO system based on strontium hexaferrite ceramic in concrete matrix. The method of producing SM has been advanced technologically; this technological effectiveness allows the SM to be used in ex-vessel core catchers with corium spreading as well as in crucible-type core catchers. Critical properties regarding the efficiency of SM in ex-vessel core catchers, such as porosity, pycnometric density, apparent density, solidus and liquidus temperatures, and water content have been measured. Suitable fractions of SrFe12O19 and high alumina cement (HAC) were found in the SM based on thermodynamic analysis of the SM/corium interaction. The use of sacrificial steel as an additional heat adsorption component in the core catcher allowed us to increase the mass fraction range of SrFe12O19 in the SM from 0.3-0.5 to 0.3-0.85. The activation temperature of the SM/corium interaction has been shown to correspond to the liquidus temperature of the local composition at the SM/corium interface. The calculated value of this temperature was 1716 °C. Analysis of phase transformations in the SrO-Fe2O3 system revealed advantages of the SrFe12O19-based sacrificial material compared with the Fe2O3-contained material owing to the time proximity of SrFe12O19 decomposition and corium interaction activation.

  14. Method of Manufacturing A Porous Polymer Component Involving Use of A Dissolvable, Sacrificial Material

    DEFF Research Database (Denmark)

    Mohanty, Soumyaranjan Technical University of Denmark,

    The present invention relates to a method of manufacturing a porous polymer component 1 with structured and/or random pores 4 and/or channels 5. The method comprises arranging a dissolvable, sacrificial material 2 in a geometrical arrangement corresponding to an inner structure to be obtained in the polymer component 1. A component material 3, which is to form the final component 1, is arranged so that it surrounds at least a majority of the sacrificial material 2, and subsequently the sacrificial material 2 is dissolved and removed from the component material 3. The sacrificial material 2 and thereby the resulting inner structure of the component 1 is arranged in a controlled and reproducible manner. The sacrificial material 2 and possibly also the component material 3 may e.g. be arranged by use of a 3D-printer or manually. The method may e.g. be used to manufacture a three-dimensional scaffold for tissue engineering.

  15. Method of Manufacturing A Porous Polymer Component Involving Use of A Dissolvable, Sacrificial Material

    DEFF Research Database (Denmark)

    The present invention relates to a method of manufacturing a porous polymer component 1 with structured and/or random pores 4 and/or channels 5. The method comprises arranging a dissolvable, sacrificial material 2 in a geometrical arrangement corresponding to an inner structure to be obtained in the polymer component 1. A component material 3, which is to form the final component 1, is arranged so that it surrounds at least a majority of the sacrificial material 2, and subsequently the sacrifici...

  16. Homeotropic Alignment of a Discotic Liquid Crystal Induced by a Sacrificial Layer

    DEFF Research Database (Denmark)

    Pouzet, Eric; De Cupere, Vinciane

    2009-01-01

    A convenient method to induce face-on orientation of an alkoxy phtalocyanine discotic mesogen is described. The alignment is imposed by the confinement of the discotic thin films with a top sacrificial polymer layer that is easily removed by washing with a selective solvent, after thermal annealing. Thin films have been characterized by optical and atomic force microscopy, UV-Vis absorption spectroscopy, and grazing incidence wide angle X-ray scattering. The data converge in showing the central role of the sacrificial layer in promoting alignment with the planar molecules orienting parallel to the substrate in an essentially homeotropic arrangement over large lateral length scales and the persistence of this desirable alignment after removal of the layer.

  17. Methods for making thin layers of crystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Lagally, Max G; Paskiewicz, Deborah M; Tanto, Boy

    2013-07-23

    Methods for making growth templates for the epitaxial growth of compound semiconductors and other materials are provided. The growth templates are thin layers of single-crystalline materials that are themselves grown epitaxially on a substrate that includes a thin layer of sacrificial material. The thin layer of sacrificial material, which creates a coherent strain in the single-crystalline material as it is grown thereon, includes one or more suspended sections and one or more supported sections.

  18. Development of an SU-8 MEMS process with two metal electrodes using amorphous silicon as a sacrificial material

    KAUST Repository

    Ramadan, Khaled S.

    2013-02-08

    This work presents an SU-8 surface micromachining process using amorphous silicon as a sacrificial material, which also incorporates two metal layers for electrical excitation. SU-8 is a photo-patternable polymer that is used as a structural layer for MEMS and microfluidic applications due to its mechanical properties, biocompatibility and low cost. Amorphous silicon is used as a sacrificial layer in MEMS applications because it can be deposited in large thicknesses, and can be released in a dry method using XeF2, which alleviates release-based stiction problems related to MEMS applications. In this work, an SU-8 MEMS process was developed using ;-Si as a sacrificial layer. Two conductive metal electrodes were integrated in this process to allow out-of-plane electrostatic actuation for applications like MEMS switches and variable capacitors. In order to facilitate more flexibility for MEMS designers, the process can fabricate dimples that can be conductive or nonconductive. Additionally, this SU-8 process can fabricate SU-8 MEMS structures of a single layer of two different thicknesses. Process parameters were optimized for two sets of thicknesses: thin (5-10 m) and thick (130 m). The process was tested fabricating MEMS switches, capacitors and thermal actuators. © 2013 IOP Publishing Ltd.

  19. Fabrication of relaxer-based piezoelectric energy harvesters using a sacrificial poly-Si seeding layer

    KAUST Repository

    Fuentes-Fernandez, E. M A

    2014-08-07

    The effect of a polycrystalline silicon (poly-Si) seeding layer on the properties of relaxor Pb(Zr0.53,Ti0.47)O3-Pb(Zn1/3,Nb2/3)O3 (PZT-PZN) thin films and energy-harvesting cantilevers was studied. We deposited thin films of the relaxor on two substrates, with and without a poly-Si seeding layer. The seeding layer, which also served as a sacrificial layer to facilitate cantilever release, was found to improve morphology, phase purity, crystal orientation, and electrical properties. We attributed these results to reduction of the number of nucleation sites and, therefore, to an increase in relaxor film grain size. The areal power density of the wet-based released harvester was measured. The power density output of the energy harvester with this relaxor composition and the poly-Si seeding layer was 325 ?W/cm2.

  20. Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

    OpenAIRE

    Costescu Ruxandra; Deneke Christoph; Thurmer Dominic; Schmidt Oliver

    2009-01-01

    Abstract The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The &#...

  1. Enhancing mechanical performance of a covalent self-healing material by sacrificial noncovalent bonds.

    Science.gov (United States)

    Neal, James A; Mozhdehi, Davoud; Guan, Zhibin

    2015-04-15

    Polymers that repair themselves after mechanical damage can significantly improve their durability and safety. A major goal in the field of self-healing materials is to combine robust mechanical and efficient healing properties. Here, we show that incorporation of sacrificial bonds into a self-repairable network dramatically improves the overall mechanical properties. Specifically, we use simple secondary amide side chains to create dynamic energy dissipative hydrogen bonds in a covalently cross-linked polymer network, which can self-heal via olefin cross-metathesis. We envision that this straightforward sacrificial bonding strategy can be employed to improve mechanical properties in a variety of self-healing systems. PMID:25790015

  2. Film transfer enabled by nanosheet seed layers on arbitrary sacrificial substrates

    Directory of Open Access Journals (Sweden)

    A. P. Dral

    2015-05-01

    Full Text Available An approach for film transfer is demonstrated that makes use of seed layers of nanosheets on arbitrary sacrificial substrates. Epitaxial SrTiO3, SrRuO3, and BiFeO3 films were grown on Ca2Nb3O10 nanosheet seed layers on phlogopite mica substrates. Cleavage of the mica substrates enabled film transfer to flexible polyethylene terephthalate substrates. Electron backscatter diffraction, X-ray diffraction, and atomic force microscopy confirmed that crystal orientation and film morphology remained intact during transfer. The generic nature of this approach is illustrated by growing films on zinc oxide substrates with a nanosheet seed layer. Film transfer to a flexible substrate was accomplished via acid etching.

  3. Thermophysical property calculation of core melt diluted by oxide sacrificial material

    International Nuclear Information System (INIS)

    Diluting the core melt with oxide sacrificial material (OSM) during in-vessel retention (IVR) is a newly proposed severe-accident-management strategy of advanced LWR. When severe accident occurs, the OSM is melted by the relocated core melt. resulting in the formation of a ternary liquid mixture of core melt and OSM in the corium. To select OSM and evaluate the heat flux on the vessel outer surface, and to assess the feasibility of the dilution design scheme, the thermophysical properties of the formed multi-component mixture should be obtained first. In this paper, the thermophysical properties of Fe3O4, TiO2 and Al2O3 were compared. Density, specific heat, thermal conductivity and viscosity of the molten ternary mixture UO2-ZrO2-OSM were also calculated. The results show that to ensure the inverse stratification to occur, implying that the oxide layer locates on top of the metallic layer, the required minimum mass of Fe3O4 should be larger than that of TiO2 and Al2O3. The specific heat and thermal conductivity of the ternary mixture increase with OSM mass, while the viscosity decreases as the mass of OSM increases. Moreover at a given temperature, the molten mixture with a lower melting point also has a smaller viscosity. (authors)

  4. Multiscale ommatidial arrays with broadband and omnidirectional antireflection and antifogging properties by sacrificial layer mediated nanoimprinting.

    Science.gov (United States)

    Raut, Hemant Kumar; Dinachali, Saman Safari; Loke, Yee Chong; Ganesan, Ramakrishnan; Ansah-Antwi, Kwadwo Konadu; Góra, Aleksander; Khoo, Eng Huat; Ganesh, V Anand; Saifullah, Mohammad S M; Ramakrishna, Seeram

    2015-02-24

    Moth's eye inspired multiscale ommatidial arrays offer multifunctional properties of great significance in optoelectronic devices. However, a major challenge remains in fabricating these arrays on large-area substrates using a simple and scalable technique. Here we present the fabrication of these multiscale ommatidial arrays over large areas by a distinct approach called sacrificial layer mediated nanoimprinting, which involves nanoimprinting aided by a sacrificial layer. The fabricated arrays exhibited excellent pattern uniformity over the entire patterned area. Optimum dimensions of the multiscale ommatidial arrays determined by the finite-difference time domain simulations served as the design parameters for replicating the arrays on glass. A broadband suppression of reflectance to a minimum of ?1.4% and omnidirectional antireflection for highly oblique angles of incidence up to 70° were achieved. In addition, superhydrophobicity and superior antifogging characteristics enabled the retention of optical properties even in wet and humid conditions, suggesting reliable optical performance in practical outdoor conditions. We anticipate that these properties could potentially enhance the performance of optoelectronic devices and minimize the influence of in-service conditions. Additionally, as our technique is solely nanoimprinting-based, it may enable scalable and high-throughput fabrication of multiscale ommatidial arrays. PMID:25634665

  5. Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

    Directory of Open Access Journals (Sweden)

    Costescu Ruxandra

    2009-01-01

    Full Text Available Abstract The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The “etch suppression” area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.

  6. Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

    Science.gov (United States)

    Costescu, Ruxandra M.; Deneke, Christoph; Thurmer, Dominic J.; Schmidt, Oliver G.

    2009-12-01

    The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The “etch suppression” area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.

  7. Layered materials

    Science.gov (United States)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and an overview of current areas of research interest.

  8. Generation of cavities in silicon wafers by laser ablation using silicon nitride as sacrificial layer

    Energy Technology Data Exchange (ETDEWEB)

    Lerner, B., E-mail: blerner@cnea.gov.ar [Grupo MEMS, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Perez, M.S.; Toro, C.; Lasorsa, C.; Rinaldi, C.A.; Boselli, A.; Lamagna, A. [Grupo MEMS, Comision Nacional de Energia Atomica, Buenos Aires (Argentina)

    2012-01-15

    Throughout this investigation, experiments on laser ablation with silicon (Si) wafers have been performed using silicon nitride (Si{sub 3}N{sub 4}) as a sacrificial layer to find the optimal fluence capable of removing the Si{sub 3}N{sub 4}, which allows the subsequent anisotropic etching in Si with potassium hydroxide. As a result, an alternative to the traditional micromachining techniques that require more steps and processing times has been introduced. The effect of the pulse numbers on Si wafers has been studied and it has been observed that when increasing the pulse numbers at the same fluence, the capacity of the pyramidal cavity formed was greater than using only one pulse at higher fluences. Microcavities were performed with a floating Si{sub 3}N{sub 4} layer. This happens to be very useful for the development of drug delivery systems and the manufacture of microarrays. Microcavities were also used as masters for the fabrication of microionizers in polydimethyl siloxane (PDMS).

  9. Using top graphene layer as sacrificial protection during dielectric atomic layer deposition

    OpenAIRE

    Tang, Xiaohui; Reckinger, Nicolas; Poncelet, Olivier; Louette, Pierre; Colomer, Jean-François; Raskin, Jean-Pierre; Hackens, Benoit; Francis, Laurent A.

    2014-01-01

    We investigate the structural damage of graphene underlying dielectrics (HfO2 and Al2O3) by remote plasma-enhanced atomic layer deposition (PE-ALD). Dielectric film is grown on bilayer graphene without inducing significant damage to the bottom graphene layer. Based on Raman spectra, we demonstrate that the bottom graphene layer has the salient features of single layer graphene. During the initial half-cycle PE-ALD, the upper graphene layer reacts with the metal precursor, fo...

  10. UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration.

    Science.gov (United States)

    Chong, J Y; Aba, N F D; Wang, B; Mattevi, C; Li, K

    2015-01-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200?hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8?L m(-2) h(-1) bar(-1) for water, and 0.14 to 7.5?L m(-2) h(-1) bar(-1) for acetone, with an unchanged low molecular weight cut off (~250?Da). PMID:26527173

  11. UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

    Science.gov (United States)

    Chong, J. Y.; Aba, N. F. D.; Wang, B.; Mattevi, C.; Li, K.

    2015-11-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200?hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8?L m?2 h?1 bar?1 for water, and 0.14 to 7.5?L m?2 h?1 bar?1 for acetone, with an unchanged low molecular weight cut off (~250?Da).

  12. Screen printing of a capacitive cantilever-based motion sensor on fabric using a novel sacrificial layer process for smart fabric applications

    International Nuclear Information System (INIS)

    Free-standing cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By printing additional conductive layers, a complete capacitive motion sensor on fabric using only screen printing has been fabricated. This type of free-standing structure cannot currently be fabricated using conventional fabric manufacturing processes. In addition, compared to conventional smart fabric fabrication processes (e.g. weaving and knitting), screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, a range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. Four cantilevers with different lengths have been printed on fabric using a five-layer structure with a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. Two silver electrodes, one on top of the cantilever and the other on top of the fabric, are used to capacitively detect the movement of the cantilever. In this way, an entirely printed motion sensor is produced on a standard fabric. The motion sensor was initially tested on an electromechanical shaker rig at a low frequency range to examine the linearity and the sensitivity of each design. Then, these sensors were individually attached to a moving human forearm to evaluate more representative results. A commercial accelerometer (Microstrain G-link) was mounted alongside for comparison. The printed sensors have a similar motion response to the commercial accelerometer, demonstrating the potential of a printed smart fabric motion sensor for use in intelligent clothing applications. (paper)

  13. Screen printing of a capacitive cantilever-based motion sensor on fabric using a novel sacrificial layer process for smart fabric applications

    Science.gov (United States)

    Wei, Yang; Torah, Russel; Yang, Kai; Beeby, Steve; Tudor, John

    2013-07-01

    Free-standing cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By printing additional conductive layers, a complete capacitive motion sensor on fabric using only screen printing has been fabricated. This type of free-standing structure cannot currently be fabricated using conventional fabric manufacturing processes. In addition, compared to conventional smart fabric fabrication processes (e.g. weaving and knitting), screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, a range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. Four cantilevers with different lengths have been printed on fabric using a five-layer structure with a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. Two silver electrodes, one on top of the cantilever and the other on top of the fabric, are used to capacitively detect the movement of the cantilever. In this way, an entirely printed motion sensor is produced on a standard fabric. The motion sensor was initially tested on an electromechanical shaker rig at a low frequency range to examine the linearity and the sensitivity of each design. Then, these sensors were individually attached to a moving human forearm to evaluate more representative results. A commercial accelerometer (Microstrain G-link) was mounted alongside for comparison. The printed sensors have a similar motion response to the commercial accelerometer, demonstrating the potential of a printed smart fabric motion sensor for use in intelligent clothing applications.

  14. A potential method of containing rockburst damage and enhancing safety using a sacrificial layer

    Scientific Electronic Library Online (English)

    T.R., Stacey; E., Rojas.

    Full Text Available Rockbursts continue to be a scourge in the mining industry, being responsible for accidents and damage to mining excavations. Although the problem has been present for more than a century, and although much research has been carried out, a solution is still elusive. Determination of, firstly, the de [...] mand on the support system imposed in the rockburst and, secondly, the capacity of the support system, cannot be carried out with any confidence, and therefore rockburst support cannot be designed using a conventional design approach. In contrast with the conventional approach, observations of rockburst damage in a mine have revealed a possible alternative approach to rockburst support - sacrificial support. It was observed, in rockburst events, that a support system consisting of concrete panels restrained by grouted cables was destroyed, and the concrete panels were ejected. However, the rock behind the panels remained apparently undamaged and in place. This behaviour reignited the concept of sacrificial support, conceived more than 20 years ago, and which is described in this paper. The remedial solution implemented on the mine, involving cables wrapped over the panels and retained by grouting into boreholes, has been subjected to rockburst loading and has confirmed the validity of the sacrificial support concept. The concept of sacrificial support may be controversial, but is deliberately presented here with the aim of generating discussions and contributions, and with the ultimate aim of improving safety and reducing rockburst damage in mines.

  15. Heat Transfer Calculation of core melt diluted by oxide sacrificial material during in-vessel retention

    International Nuclear Information System (INIS)

    Diluting the core melt with oxide sacrificial material (OSM) during in-vessel retention (IVR) is a newly proposed severe-accident-management strategy of advanced LWRs. When severe accident occurs, the relocated core melt is diluted by OSM, resulting in the inverse stratification of melt pool configuration. Therefore, the researches on the calculations of heat transfer of melt pool are essential to optimize the component of OSM and evaluate the effectiveness of the strategy. The heat flux on the vessel outer surface after diluting the core melt with Fe3O4, TiO2 and Al2O3, respectively was calculated. The results show that the structure of upper plenum will melt due to the intense heat radiation after OSM is used. The maximum heat flux on the vessel outer surface reduces with the increase of OSM. When the volume of the OSM ceramics reaches 15 m3, the reactor vessel length should be increased by approximately 2 m. In this case, the heat flux reduces about 45% compared to the reactors without OSM. Moreover, the reduction of heat flux is most pronounced as Fe3O4 is used. In addition, the melting point of UO2-ZrO2-OSM affects the appearance of a crust on the surface of the oxide mixture, which in turn influences the maximum heat flux on the vessel outer surface. (authors)

  16. BEOL compatible high tunnel magneto resistance perpendicular magnetic tunnel junctions using a sacrificial Mg layer as CoFeB free layer cap

    Science.gov (United States)

    Swerts, J.; Mertens, S.; Lin, T.; Couet, S.; Tomczak, Y.; Sankaran, K.; Pourtois, G.; Kim, W.; Meersschaut, J.; Souriau, L.; Radisic, D.; Van Elshocht, S.; Kar, G.; Furnemont, A.

    2015-06-01

    Perpendicularly magnetized MgO-based tunnel junctions are envisaged for future generation spin-torque transfer magnetoresistive random access memory devices. Achieving a high tunnel magneto resistance and preserving it together with the perpendicular magnetic anisotropy during BEOL CMOS processing are key challenges to overcome. The industry standard technique to deposit the CoFeB/MgO/CoFeB tunnel junctions is physical vapor deposition. In this letter, we report on the use of an ultrathin Mg layer as free layer cap to protect the CoFeB free layer from sputtering induced damage during the Ta electrode deposition. When Ta is deposited directly on CoFeB, a fraction of the surface of the CoFeB is sputtered even when Ta is deposited with very low deposition rates. When depositing a thin Mg layer prior to Ta deposition, the sputtering of CoFeB is prevented. The ultra-thin Mg layer is sputtered completely after Ta deposition. Therefore, the Mg acts as a sacrificial layer that protects the CoFeB from sputter-induced damage during the Ta deposition. The Ta-capped CoFeB free layer using the sacrificial Mg interlayer has significantly better electrical and magnetic properties than the equivalent stack without protective layer. We demonstrate a tunnel magneto resistance increase up to 30% in bottom pinned magnetic tunnel junctions and tunnel magneto resistance values of 160% at resistance area product of 5 ?.?m2. Moreover, the free layer maintains perpendicular magnetic anisotropy after 400 °C annealing.

  17. Silica sacrificial layer-assisted in-plane incorporation of Au nanoparticles into mesoporous titania thin films through different reduction methods.

    Science.gov (United States)

    Liang, Chih-Peng; Yamauchi, Yusuke; Liu, Chia-Hung; Wu, Kevin C-W

    2013-06-28

    This study focuses on the incorporation of gold nanoparticles (Au NPs) into our previously synthesized mesoporous titania thin films consisting of titania nanopillars and inverse mesospace (C. W. Wu, T. Ohsuna, M. Kuwabara and K. Kuroda, J. Am. Chem. Soc., 2006, 128, 4544-4545, denoted as MTTFs). Recently, mesoporous titania materials doped with noble metals such as gold have attracted considerable attention because noble metals can enhance the efficiency of mesoporous titania-based devices. In this research, we attempted to use four different reduction methods (i.e., thermal treatment, photo irradiation, liquid immersion, and vapor contacting) to introduce gold nanoparticles (Au NPs) into MTTFs. The synthesized Au@MTTFs were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We further systematically investigated the formation mechanism of gold nanoparticles on the external and internal surfaces of the MTTFs. With the assistance of a silica sacrificial layer, well-dispersed Au NPs with sizes of 4.1 nm were obtained inside the MTTF by photo irradiation. The synthesized Au@MTTF materials show great potential in various photo-electronic and photo-catalytic applications. PMID:23633080

  18. Fabrication of 3-nm-thick Si3N4 membranes for solid-state nanopores using the poly-Si sacrificial layer process

    Science.gov (United States)

    Yanagi, Itaru; Ishida, Takeshi; Fujisaki, Koji; Takeda, Ken-Ichi

    2015-10-01

    To improve the spatial resolution of solid-state nanopores, thinning the membrane is a very important issue. The most commonly used membrane material for solid-state nanopores is silicon nitride (Si3N4). However, until now, stable wafer-scale fabrication of Si3N4 membranes with a thickness of less than 5?nm has not been reported, although a further reduction in thickness is desired to improve spatial resolution. In the present study, to fabricate thinner Si3N4 membranes with a thickness of less than 5?nm in a wafer, a new fabrication process that employs a polycrystalline-Si (poly-Si) sacrificial layer was developed. This process enables the stable fabrication of Si3N4 membranes with thicknesses of 3?nm. Nanopores were fabricated in the membrane using a transmission electron microscope (TEM) beam. Based on the relationship between the ionic current through the nanopores and their diameter, the effective thickness of the nanopores was estimated to range from 0.6 to 2.2?nm. Moreover, DNA translocation through the nanopores was observed.

  19. Platinum ion implantation into single crystal zirconia with a carbon sacrificial layer on the surface

    International Nuclear Information System (INIS)

    Single crystal samples of (100) oriented yttria stabilized cubic zirconia are implanted with Pt ions to doses up to 6 x 1017/cm2. The previous studies showed that the retained Pt dose was too small due to the sputter limit. To overcome this problem, a C film was deposited on the surface of some samples before implantation. The implanted samples were annealed isothermally in air at 400--1,200 C, and were analyzed with RBS-C and TEM. The C-layer has been found to be very effective for protecting the sample surface from sputtering and thus increasing the Pt concentration by a factor of two, up to 33 mol.% Pt. The as-implanted Pt was nonsubstitutional. After annealing at 1,200 C for 1 h, Pt diffused to large depths, and showed a substitutional fraction of about 23%. The detailed TEM measurements on the microstructure and damage of the implanted layer show that after annealing at these temperatures the recovery of ion damage is incomplete. Pt atoms undergo substantial migration concurrently. The Pt at first dissolves in the matrix (though not substitutionally), diffuses and precipitates again at high temperature

  20. Buckle-driven delamination of hydrophobic micro-, nano-, and heterostructured membranes without a sacrificial layer

    Science.gov (United States)

    Larsen, George K.; Zhao, Yiping

    2013-10-01

    A fabrication method, based on thin film buckling, is demonstrated to form unique membranes that can be used for applications in optics and biosensing. This method should be applicable to a variety of material systems, which, along with its simplicity and compatibility with different film architectures, allows for widespread implementation.A fabrication method, based on thin film buckling, is demonstrated to form unique membranes that can be used for applications in optics and biosensing. This method should be applicable to a variety of material systems, which, along with its simplicity and compatibility with different film architectures, allows for widespread implementation. Electronic supplementary information (ESI) available: Monolayer characterization and details; morphological parameters of the membranes; diffraction pattern images; rigorous coupled wave analysis; pattern transfer fidelity; experimental details. See DOI: 10.1039/c3nr03933a

  1. A concave-patterned TiN/PECVD-Si3N4?/TiN diaphragm MEMS acoustic sensor based on a polyimide sacrificial layer

    Science.gov (United States)

    Lee, Jaewoo; Jeon, J. H.; Je, C. H.; Kim, Y.-G.; Lee, S. Q.; Yang, W. S.; Lee, J. S.; Lee, S.-G.

    2015-12-01

    In this paper, we present a concave-patterned TiN/PECVD-Si3N4?/TiN diaphragm micro-electro-mechanical system (MEMS) acoustic sensor based on a polyimide sacrificial layer. The use of the spin-coated polyimide eliminates the additional Al pad process of conventional device fabrication due to simple O2 ashing to release the sacrificial layer, simplifying the photolithography process. Also, to adjust the acoustic sensor for a bottom-ported package, its diaphragm was implemented to be placed over the back-plate. The TiN/PECVD-Si3N4/TiN multi-layer diaphragm was formed with the stress controllability of PECVD-Si3N4 from???162?MPa to??+109?MPa. Furthermore, a parallel-plate capacitance model on the basis of an approximately linearized electric field method (ALEM) is proposed to evaluate the capacitance of two plates. The modelled capacitance showed less than 3.7% error in FEM simulation, demonstrating the validity of the proposed model. At a zero-bias voltage, the effective intrinsic and parasitic capacitances in the active area were 1.656 pF and 0.388 pF, respectively. Moreover, with a pull-in analytical model by using ALEM, the effective tensile stress for the diaphragm was extracted to??+31.5?MPa, where the pull-in voltage was 10.7?V. In succession, the dynamic response for the open-circuit sensitivity was modelled with an equivalent circuit model based on lumped parameters. The measured open-circuit sensitivity of???45.1 dBV Pa?1 at 1?kHz with a bias of 9.6?V was only slightly different from the modelled sensitivity of???45.0 dBV Pa?1. Thus, these results demonstrate that the proposed sensor is suitable for a front-end voice capture module.

  2. Structuration of thin bridge and cantilever structures in thick-film technology using mineral sacrificial materials

    OpenAIRE

    Maeder, Thomas; Jacq, Caroline; Fournier, Yannick; Hraiz, Wassim; Ryser, Peter

    2009-01-01

    Thick-film and LTCC (Low Temperature Cofired Ceramic) technologies find increasing use in meso-scale sensors, actuators and related devices that feature excellent dimensional, thermal and chemical stability at moderate cost. While several materials and processes allow fabrication of structures such as channels, membranes and relatively short bridges, obtaining slender bridges and cantilevers with good shape control for applications such as microforce sensors has hitherto remained ...

  3. Manufacture of micro-electro-mechanical-system using sacrificial layer made of silicon, useful for micro-electro-mechanical-system device architecture, e.g. radio-frequency capacitive switch and current switch

    OpenAIRE

    IONESCU, M.A.; FLUCKIGER, PH; HIBERT, C; FRITSCHI, R; POTT, V

    2002-01-01

    NOVELTY - A micro-electro-mechanical-system (MEMS) is manufactured by the use of a sacrificial layer that is made of silicon. USE - The invention is used in surface micromachining for the manufacture of a MEMS containing a suspended metal layer or MEMS device architecture. MEMS device is a suspended gate metal oxide semiconductor field effect transistor (SG-MOSFET). It is used as radio-frequency capacitive switch, current switch, radio-frequency tuneable capacitor, magnetic field sensor, acce...

  4. Hot sodium-triggered thermo-chemical degradation of concrete aggregates in the sodium resistant sacrificial layers of fast breeder reactors

    International Nuclear Information System (INIS)

    Highlights: • Concrete aggregates were exposed to liquid sodium exposure at 550 °C. • Thermal and chemical effects were studied using megascopic and micro-analytical techniques. • Aggregates underwent significant thermo-chemical degradation upon exposure. • Limestone found more suitable for sodium environment than siliceous aggregate. - Abstract: Sodium is used as an efficient coolant in fast breeder reactor (FBR) for extracting nuclear heat from its high power density core to steam generator, to produce electricity. Accidentally spilled Sodium at elevated temperatures of 550 °C or above may interact with concrete leading to its deterioration. A sacrificial concrete layer is provided on the structural concrete to mitigate the harmful impacts of these interactions. Locally available crushed rocks like limestone and granite are employed as aggregates in sacrificial and structural concrete respectively. Rocks are naturally occurring multi-mineral and multiphase inorganic systems of the earth. Aggregates are the main constituents of concrete accounting for 70–80% of its mass. In this paper, an attempt is made to study the physico-chemical modifications that may occur in the aggregates during the interactions between liquid sodium and the aggregates of concrete. The experimental strategy consists of heating of granite, limestone and river sand aggregates at 550 °C for 30 min and further treating them with 1 Normal aqueous solution of NaOH, to differentiate thermal and chemical effects. Furthermore, sodium-aggregate interaction study at 550 °C was conducted to characterize the combined effects of heat and sodium. Siliceous aggregates (granite and river sand) were found to be easily attacked by ferric oxidation during heating in air and also subjected to rapid chemical reactions with liquid NaOH, producing mineral phases of sodium silicate, sodium orthosilicates, calcium orthosilicates and sodium carbonates. Initiation and propagation of cracking in the siliceous aggregates are sustained due to differential thermal expansion of minerals and chemical invasion of inter-granular structures. Limestone, on the other hand, was mostly stable, and its thermal performance was affected by the fraction of deleterious accessory minerals present in it. Combined action of corrosive NaOH and heat induced cracks in hot sodium environment at 550 °C may lead to more drastic degradation of concrete with siliceous aggregate than with limestone aggregate

  5. Building biomedical materials layer-by-layer

    Directory of Open Access Journals (Sweden)

    Paula T. Hammond

    2012-05-01

    Full Text Available In this materials perspective, the promise of water based layer-by-layer (LbL assembly as a means of generating drug-releasing surfaces for biomedical applications, from small molecule therapeutics to biologic drugs and nucleic acids, is examined. Specific advantages of the use of LbL assembly versus traditional polymeric blend encapsulation are discussed. Examples are provided to present potential new directions. Translational opportunities are discussed to examine the impact and potential for true biomedical translation using rapid assembly methods, and applications are discussed with high need and medical return.

  6. CMUTs with high-K atomic layer deposition dielectric material insulation layer.

    Science.gov (United States)

    Xu, Toby; Tekes, Coskun; Degertekin, F

    2014-12-01

    Use of high-? dielectric, atomic layer deposition (ALD) materials as an insulation layer material for capacitive micromachined ultrasonic transducers (CMUTs) is investigated. The effect of insulation layer material and thickness on CMUT performance is evaluated using a simple parallel plate model. The model shows that both high dielectric constant and the electrical breakdown strength are important for the dielectric material, and significant performance improvement can be achieved, especially as the vacuum gap thickness is reduced. In particular, ALD hafnium oxide (HfO2) is evaluated and used as an improvement over plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (Six)Ny)) for CMUTs fabricated by a low-temperature, complementary metal oxide semiconductor transistor-compatible, sacrificial release method. Relevant properties of ALD HfO2) such as dielectric constant and breakdown strength are characterized to further guide CMUT design. Experiments are performed on parallel fabricated test CMUTs with 50-nm gap and 16.5-MHz center frequency to measure and compare pressure output and receive sensitivity for 200-nm PECVD Six)Ny) and 100-nm HfO2) insulation layers. Results for this particular design show a 6-dB improvement in receiver output with the collapse voltage reduced by one-half; while in transmit mode, half the input voltage is needed to achieve the same maximum output pressure. PMID:25474786

  7. A sacrificial SU-8 mask for direct metallization on PDMS

    International Nuclear Information System (INIS)

    A new fabrication technology utilizing SU-8 as a sacrificial mask for metallization of the PDMS surface is presented. The sacrificial SU-8 layer process offers superior performance for reliable and repeatable metallization on the PDMS layer. Sacrificial SU-8 masks from 45 µm to 250 µm thickness are successfully fabricated on the PDMS layer to pattern gold on the PDMS surface. These layers are successfully peeled off from the PDMS surface after a metal deposition step. Metal lines from 10 µm to 500 µm wide and 1 mm to 50 mm long are successfully patterned and tested. Furthermore, the sacrificial SU-8 mask can be removed within minutes to realize metal patterns on the PDMS surface and does not leave any residue after removal of the SU-8 layer. As this new process is intended for use in fabrication of microfluidic and biomedical microdevices, electrodes of an electro-enzymatic glucose sensor are presented to demonstrate the technology

  8. Surface imprinting on nano-TiO{sub 2} as sacrificial material for the preparation of hollow chlorogenic acid imprinted polymer and its recognition behavior

    Energy Technology Data Exchange (ETDEWEB)

    Li Hui, E-mail: lihuijsdx@163.com [College of Chemistry and Chemical Engineering, Jishou University, Hunan 416000, Jishou (China); Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan 416000, Jishou (China); Li Gui [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan 416000, Jishou (China); Li Zhiping; Lu Cuimei; Li Yanan [College of Chemistry and Chemical Engineering, Jishou University, Hunan 416000, Jishou (China); Tan Xianzhou [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan 416000, Jishou (China)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Used surface imprinting technique with nano-TiO{sub 2} as sacrificial support material. Black-Right-Pointing-Pointer Improved adsorption capability of the H-MIP1 compared with the previous work. Black-Right-Pointing-Pointer Excellent mass transfer dynamics for the H-MIP1. Black-Right-Pointing-Pointer Investigated adsorption thermodynamic of the H-MIP1. - Abstract: Surface imprinting chlorogenic acid (CGA) on nano-TiO{sub 2} particles as sacrificial support material was successfully performed by using 4-vinylpyridine (4-VP) as functional monomer to obtain a hollow CGA-imprinted polymer (H-MIP1). Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM) were utilized for structurally characterizing the polymers obtained and adsorption dynamics and thermodynamic behavior investigated according to different models. Binding selectivity, adsorption capacity and the reusability for this H-MIP1 were also evaluated. This hollow CGA imprinted polymer shows rapid binding dynamics and higher binding capability toward the template molecules. The pseudo first-order kinetic model was shown best to describe the binding process of CGA on the H-MIP1 and Langmuir isotherm model best to fit the experimental adsorption isotherm data. Through adsorption isotherms at different temperatures, thermodynamic parameter values were obtained. Selectivity coefficients for the H-MIP1 toward the template were 2.209, 3.213, 1.746 and 2.353 relative to CA, VA, PCA and GA, respectively. This H-MIP1 was also indicated with a good imprint effect and a high capability to capture CGA from methanol extract of Eucommia ulmoides (E. ulmoides) leaves. Additionally, a good reusability for this imprinted polymer was exhibited during repeated adsorption-desorption use.

  9. Liquid phase epitaxy monocrystalline silicon thin film on sacrificial layers for carrying out cheap photovoltaic devices; Croissance de silicium monocristallin en couche mince par epitaxie en phase liquide sur couches sacrificielles pour report sur substrat faible cout pour applications photovoltaiques

    Energy Technology Data Exchange (ETDEWEB)

    Berger, S.

    2003-07-01

    This work deals with the use of sacrificial layers obtained by liquid phase epitaxy for manufacturing solar cells. Three kinds of sacrificial layers are studied: the macroporous silicon or grids, the nano-porous silicon and the layers embrittled by ionic implantation. The macroporous silicon allows to control the porosity and then the embrittlement of the layer. It is easily transferable and detachable. The used substrate is recyclable. The transfer is carried out before the growth. A study on silicon for allowing an electrochemical attack has been carried out. The wished characteristics of the grids have been defined in order to be able to make a growth above it. The transfer, followed by the growth, has been carried out. The orientation of the support being (100), the morphology of the layer is an assembly of pyramids. The adjustment of the parameters allows to improve the coalescence between the pyramids. During this work, a phenomenon has been observed: the consumption of the growth substrate silicon. A study has been carried out on SOI supports for adjusting the growth parameters. In order to decrease the costs, it has been considered to carry out the epitaxy before the transfer. The nano-porous silicon layers have then appeared as the continuity of the study. The characteristics of this porous silicon have been studied to allow the detachment of the epitaxied layer. The layers obtained on the substrate (100) are formed of pyramids whose coalescence depends of the parameters of the epitaxy. On the substrate (111), the layers obtained are continuous and homogeneous and the detachment is carried out. Another solution is to adapt the SMART-CUT ionic implantation technique to the photovoltaic field. (O.M.)

  10. Application of graphite-based sacrificial layers for fabrication of LTCC (low temperature co-fired ceramic) membranes and micro-channels

    OpenAIRE

    Birol, Hansu; Maeder, Thomas; Ryser, Peter

    2007-01-01

    Fabrication of sensors and micro-fluidic structures from low temperature co- fired ceramic (LTCC) sheets is a growing interest in the micro-packaging community. Such devices usually have inner cavities, whose production is quite complicated. The most elegant method to build such structures so far achieved is by a fugitive phase that is introduced into the multilayer and removed during firing. This paper, therefore, is aimed to introduce the graphite-based sacrificial paste developed for ...

  11. Metal-Organic Framework Nanocrystals as Sacrificial Templates for Hollow and Exceptionally Porous Titania and Composite Materials.

    Science.gov (United States)

    Yang, Hui; Kruger, Paul E; Telfer, Shane G

    2015-10-01

    We report a strategy that employs metal-organic framework (MOF) crystals in two roles for the fabrication of hollow nanomaterials. In the first role the MOF crystals provide a template on which a shell of material can be deposited. Etching of the MOF produces a hollow structure with a predetermined size and morphology. In combination with this strategy, the MOF crystals, including guest molecules in their pores, can provide the components of a secondary material that is deposited inside the initially formed shell. We used this approach to develop a straightforward and reproducible method for constructing well-defined, nonspherical hollow and exceptionally porous titania and titania-based composite nanomaterials. Uniform hollow nanostructures of amorphous titania, which assume the cubic or polyhedral shape of the original template, are delivered using nano- and microsized ZIF-8 and ZIF-67 crystal templates. These materials exhibit outstanding textural properties including hierarchical pore structures and BET surface areas of up to 800 m(2)/g. As a proof of principle, we further demonstrate that metal nanoparticles such as Pt nanoparticles, can be encapsulated into the TiO2 shell during the digestion process and used for subsequent heterogeneous catalysis. In addition, we show that the core components of the ZIF nanocrystals, along with their adsorbed guests, can be used as precursors for the formation of secondary materials, following their thermal decomposition, to produce hollow and porous metal sulfide/titania or metal oxide/titania composite nanostructures. PMID:26365676

  12. Application of the GEMINI2 code to Develop the Sacrificial Concrete for the Core-catcher Experiment by KAERI

    International Nuclear Information System (INIS)

    In the late phase of a severe accident, the reactor lower vessel may fail, the hot molten corium discharging into the reactor cavity can threaten the integrity of the containment due to the combustible gas generation, the fission product release and the large amount of steam generation from the MCCI (molten core concrete interaction). Therefore, it is important to make the relocated hot molten corium cool-down in a safe and fast manner. For this purpose, KAERI has proposed a new cooling concept for the corium in a cavity by simultaneously injecting water and non-condensable gas into the nozzles embedded in the concrete basement from the bottom. From the COMET experimental results, the most important condition to achieve a cooling for a melt by a 'bottom injection' will be whether the melt can be changed into a porous structure or not. It means that the phenomena for forming a porous structure by a fuel coolant interaction during a bottom injection are the crucial mechanisms that need to be identified. The possible scenario to form a porous layer may be a 'local pressure build-up' by a strong steam generation. This pressure build-up may propagate and expand in a lateral direction. Also, this steam filled void region may iterate an expansion and shrinkage. In addition, this strong vibration and steaming may produce a porous layer. KAERI is planning to perform a core-catcher experiment for identifying the debris coolability by a bottom injection. To fulfill this experiment successfully, it is necessary to develop sacrificial concrete. The sacrificial concrete can decrease not only the corium temperature but also the viscosity. An enhanced mobility can provide a higher possibility to form a porous layer. The purpose of this study is to elucidate the CaO content in the sacrificial concrete using the GEMINI2 code. Figure 1 is the conceptual picture for the core-catcher experiment. The melt from the termite reactions will be relocated over the sacrificial concrete. The water will be injected from the bottom after the melt has eroded the sacrificial concrete. The purpose of the experiment is to estimate whether a porous layer can be formed or not. The main ingredient of the sacrificial concrete is CaO. The application of the sacrificial concrete can decrease not only the solidus temperature but also the viscosity. If the molten corium has a high solidification temperature, then even a small cooling at the begin of the bottom injection may make the most of the molten material freeze immediately. A lower viscosity can provide more mobility to a molten material. An enhanced mobility and a lowered solidification temperature can provide an enhanced possibility of forming a porous layer. Consequently, the purpose of this study is to elucidate the CaO content for the sacrificial concrete, which can make the solidus and liquidus temperature low using the GEMINI-2 code. This sacrificial concrete will be applied to a test for estimating the corium coolability under a bottom injection based on the new cooling concept developed by KAERI

  13. Thick photopolymer layers for holographic recording materials

    OpenAIRE

    García Llopis, Celia; Fimia Gil, Antonio; Pascual Villalobos, Inmaculada

    1999-01-01

    In this article the behavior of thick photopolymer layers as material for holographic recording is studied. The material used is a photopolymer based on acrylamides, consisting of acrylamide as monomer, yellowish eosin as sensitizer and triethanolamine as radical generator, all on a matrix of polyvinyl alcohol. We studied the influence of the thickness of the layer on the behavior of the photopolymer as a holographic recording material. According to Kogelnik's theory, the thickness determines...

  14. Surface micromachined PDMS microfluidic devices fabricated using a sacrificial photoresist

    International Nuclear Information System (INIS)

    PDMS is a widely used material for construction of microfluidic devices. The traditional PDMS microfabrication process, although versatile, cannot be used to form microfluidic devices with embedded tall topological features, such as thick-film electrodes and porous reactor beds. This paper presents an elegant surface micromachining process for microfluidic devices that allows complete leak-proof sealing and a conformal contact of the PDMS with tall pre-existing topographical features and demonstrates this approach by embedding 6 µm thick Ag/AgCl (high capacity 1680 µA s) electrodes inside the microchannels. In this process, thin spin-cast films of the PDMS are used as the structural material and a photoresist is used as the sacrificial material. A crucial parameter, namely adhesion of the spun-cast structural layer to the substrate, was characterized for different pre-polymer ratios using a standard tensile test, and a 1:3 (curing agent:base) combination was found to be the best with a maximum adhesion strength of 7.2 MPa. The elastic property of the PDMS allowed extremely fast release times of ?1 min of the fabricated microchannels. The versatility of this process was demonstrated by the fabrication of a pneumatic microvalve with multi-layered microchannel geometry. The valve closure occurred at 6.37 kPa

  15. Compressive Failure Mechanisms in Layered Materials

    DEFF Research Database (Denmark)

    Sørensen, Kim Dalsten

    2008-01-01

    Two important failure modes in fiber reinforced composite materials in cluding layers and laminates occur under loading conditions dominated by compression in the layer direction. These two distinctly different failure modes are 1. buckling driven delamination 2. failure by strain localization into kink bands. The present thesis falls into two parts dealing with the two failure modes. In the first part of the thesis the effects of system geometry on buckling driven delamination is investigated. ...

  16. KAPOOL experiments to simulate molten corium - sacrificial concrete interaction

    International Nuclear Information System (INIS)

    In future Light Water Reactors special devices (core catchers) might be required to prevent containment failure by basement erosion after reactor pressure vessel melt-through during a core meltdown accident. In the planned European Pressurized Reactor (EPR) the core melt is retained in the reactor cavity for ? 1 h to pick up late melts after the failure of the reactor pressure vessel. The reactor cavity is protected by a layer of sacrificial concrete and closed by a melt gate at the bottom towards the spreading compartment. After erosion of the sacrificial concrete and melt-through of the gate the core melt should be distributed homogeneously into the spreading compartment. There the melt is cooled by flooding with water. The knowledge of the sacrificial concrete erosion phase in the reactor cavity is essential for the severe accident assessment. Several KAPOOL experiments have been performed to investigate the erosion of two possible compositions of sacrificial concretes using alumina-iron thermite melts as a simulant for the core melt. Erosion rates as a function of the melt temperature and the inhomogeneity of the melt front are presented in this paper. (authors)

  17. Preface "Layer silicate materials and clays"

    OpenAIRE

    Valdre, G

    2010-01-01

    Abstract Here we report the preface entitled "Layer silicate materials and clays" related to the 14th International Clay Conference, Castellaneta Marina, Italy, June 2009. A special issue of the Philosophical Magazine collects some selected works of “Clay Science” with the purpose to show the wide range of applications and/or new fields, or recent relevant achievements in traditional, well-established subjects, or prospects of future developments, all related to material scienc...

  18. Nano transfer and nanoreplication using deterministically grown sacrificial nanotemplates

    Science.gov (United States)

    Melechko, Anatoli V. (Oak Ridge, TN); McKnight, Timothy E. (Greenback, TN); Guillorn, Michael A. (Ithaca, NY); Ilic, Bojan (Ithaca, NY); Merkulov, Vladimir I. (Knoxville, TX); Doktycz, Mitchel J. (Knoxville, TN); Lowndes, Douglas H. (Knoxville, TN); Simpson, Michael L. (Knoxville, TN)

    2012-03-27

    Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. An apparatus, includes a substrate and a nanoconduit material coupled to a surface of the substrate. The substrate defines an aperture and the nanoconduit material defines a nanoconduit that is i) contiguous with the aperture and ii) aligned substantially non-parallel to a plane defined by the surface of the substrate.

  19. Layered zeolite materials and methods related thereto

    Science.gov (United States)

    Tsapatsis, Michael; Maheshwari, Sudeep; Bates, Frank S; Koros, William J

    2013-08-06

    A novel oxide material (MIN-I) comprising YO.sub.2; and X.sub.2O.sub.3, wherein Y is a tetravalent element and X is a trivalent element, wherein X/Y=O or Y/X=30 to 100 is provided. Surprisingly, MIN-I can be reversibly deswollen. MIN-I can further be combined with a polymer to produce a nanocomposite, depolymerized to produce predominantly fully exfoliated layers (MIN-2), and pillared to produce a pillared oxide material (MIN-3), analogous to MCM-36. The materials are useful in a wide range of applications, such as catalysts, thin films, membranes, and coatings.

  20. Toughening elastomers with sacrificial bonds and watching them break.

    Science.gov (United States)

    Ducrot, Etienne; Chen, Yulan; Bulters, Markus; Sijbesma, Rint P; Creton, Costantino

    2014-04-11

    Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4 megapascals and 9 kilojoules per square meter) by introducing a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails. Chemoluminescent cross-linking molecules, which emit light as they break, map in real time where and when many of these internal bonds break ahead of a propagating crack. The simple methodology that we use to introduce sacrificial bonds, combined with the mapping of where bonds break, has the potential to stimulate the development of new classes of unfilled tough elastomers and better molecular models of the fracture of soft materials. PMID:24723609

  1. Atomic Layer Thermopile Materials: Physics and Application

    Directory of Open Access Journals (Sweden)

    H.-U. Habermeier

    2008-11-01

    Full Text Available New types of thermoelectric materials characterized by highly anisotropic Fermi surfaces and thus anisotropic Seebeck coefficients are reviewed. Early studies revealed that there is an induced voltage in high TC oxide superconductors when the surface of the films is exposed to short light pulses. Subsequent investigations proved that the effect is due to anisotropic components of the Seebeck tensor, and the type of materials is referred to atomic layer thermopile (ALT. Our recent studies indicate that multilayer thin films at the nanoscale demonstrate enhanced ALT properties. This is in agreement with the prediction in seeking the larger figure of merit (ZT thermoelectric materials in nanostructures. The study of ALT materials provides both deep insight of anisotropic transport property of these materials and at the same time potential materials for applications, such as light detector and microcooler. By measuring the ALT properties under various perturbations, it is found that the information on anisotropic transport properties can be provided. The information sometimes is not easily obtained by other tools due to the nanoscale phase coexistence in these materials. Also, some remained open questions and future development in this research direction have been well discussed.

  2. Radionuclide separations using pillared layered materials

    International Nuclear Information System (INIS)

    This is the final report of a two-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Pillared Layered Materials (PLMs) are layered inorganic ion exchangers propped apart by metal oxide pillars. PLMs have been synthesized to sorb strontium from liquid nuclear wastes. A study that compared over 60 sorbers for their ability to sorb strontium from Hanford simulants showed that PLMs were the best sorbers; strontium distribution coefficients (SrKd) > 20000 mL/g were obtained. In addition, PLMs showed a high degree of selectivity for strontium over cesium, transition metals, lanthanides and actinides. The sorption of strontium is, however, inhibited by complexants (EDTA); SrKd values drop to d values for Sr2+ and Ba2+ show a strong pH dependence; Kd values increase to >104 above pH 12. The general surface complexation mechanism explains the sorption of these cations on PLMs

  3. The role of topology and thermal backbone fluctuations on sacrificial bond efficacy in mechanical metalloproteins

    International Nuclear Information System (INIS)

    Sacrificial bonding is a ubiquitous cross-linking strategy for increasing toughness that is found throughout nature in various biological materials such as bone, wood, silk and mussel byssal threads. However, the molecular mechanism of sacrificial bonding remains only poorly understood. Molecular modeling possesses a strong potential to provide insights into the behavior of these cross-links. Here we use Monte Carlo simulations to investigate the effect of reversible sacrificial binding sites on the mechanical properties of single linear polymer chains based on load-bearing metalloproteins found in the mussel byssus. It is shown that the topology of the bonds determines the position and spacing of sacrificial force peaks, while the height of these peaks is intimately tied to the magnitude of thermal fluctuations in the chain that are dependent on effective chain length. These results bear important implications for understanding natural systems and for the generation of strong and ductile biomimetic polymers. (paper)

  4. Nanomanufacturing : nano-structured materials made layer-by-layer.

    Energy Technology Data Exchange (ETDEWEB)

    Cox, James V.; Cheng, Shengfeng; Grest, Gary Stephen; Tjiptowidjojo, Kristianto (University of New Mexico); Reedy, Earl David, Jr.; Fan, Hongyou; Schunk, Peter Randall; Chandross, Michael Evan; Roberts, Scott A.

    2011-10-01

    Large-scale, high-throughput production of nano-structured materials (i.e. nanomanufacturing) is a strategic area in manufacturing, with markets projected to exceed $1T by 2015. Nanomanufacturing is still in its infancy; process/product developments are costly and only touch on potential opportunities enabled by growing nanoscience discoveries. The greatest promise for high-volume manufacturing lies in age-old coating and imprinting operations. For materials with tailored nm-scale structure, imprinting/embossing must be achieved at high speeds (roll-to-roll) and/or over large areas (batch operation) with feature sizes less than 100 nm. Dispersion coatings with nanoparticles can also tailor structure through self- or directed-assembly. Layering films structured with these processes have tremendous potential for efficient manufacturing of microelectronics, photovoltaics and other topical nano-structured devices. This project is designed to perform the requisite R and D to bring Sandia's technology base in computational mechanics to bear on this scale-up problem. Project focus is enforced by addressing a promising imprinting process currently being commercialized.

  5. Atomic layer deposition of nanostructured materials

    CERN Document Server

    Pinna, Nicola

    2012-01-01

    Atomic layer deposition, formerly called atomic layer epitaxy, was developed in the 1970s to meet the needs of producing high-quality, large-area fl at displays with perfect structure and process controllability. Nowadays, creating nanomaterials and producing nanostructures with structural perfection is an important goal for many applications in nanotechnology. As ALD is one of the important techniques which offers good control over the surface structures created, it is more and more in the focus of scientists. The book is structured in such a way to fi t both the need of the expert reader (du

  6. Nanoprocessing of layered crystalline materials by atomic force microscopy

    Science.gov (United States)

    Miyake, Shojiro; Wang, Mei

    2015-03-01

    By taking advantage of the mechanical anisotropy of crystalline materials, processing at a single-layer level can be realized for layered crystalline materials with periodically weak bonds. Mica (muscovite), graphite, molybdenum disulfide (MoS2), and boron nitride have layered structures, and there is little interaction between the cleavage planes existing in the basal planes of these materials. Moreover, it is easy to image the atoms on the basal plane, where the processed shape can be observed on the atomic level. This study reviews research evaluating the nanometer-scale wear and friction as well as the nanometer-scale mechanical processing of muscovite using atomic force microscopy (AFM). It also summarizes recent AFM results obtained by our research group regarding the atomic-scale mechanical processing of layered materials including mica, graphite, MoS2, and highly oriented pyrolytic graphite.

  7. Love wave propagation in functionally graded piezoelectric material layer.

    Science.gov (United States)

    Du, Jianke; Jin, Xiaoying; Wang, Ji; Xian, Kai

    2007-03-01

    An exact approach is used to investigate Love waves in functionally graded piezoelectric material (FGPM) layer bonded to a semi-infinite homogeneous solid. The piezoelectric material is polarized in z-axis direction and the material properties change gradually with the thickness of the layer. We here assume that all material properties of the piezoelectric layer have the same exponential function distribution along the x-axis direction. The analytical solutions of dispersion relations are obtained for electrically open or short circuit conditions. The effects of the gradient variation of material constants on the phase velocity, the group velocity, and the coupled electromechanical factor are discussed in detail. The displacement, electric potential, and stress distributions along thickness of the graded layer are calculated and plotted. Numerical examples indicate that appropriate gradient distributing of the material properties make Love waves to propagate along the surface of the piezoelectric layer, or a bigger electromechanical coupling factor can be obtained, which is in favor of acquiring a better performance in surface acoustic wave (SAW) devices. PMID:17107699

  8. Electromagnetic cloaking by layered structure of homogeneous isotropic materials

    CERN Document Server

    Huang, Ying; Jian, Tian

    2007-01-01

    Electromagnetic invisibility cloak requires material with anisotropic distribution of the constitutive parameters deduced from a geometrical transformation as first proposed by Pendry et al. [Science 312, 1780 (2006)]. In this paper, we proposed a useful method to realize the required radius-dependent, anisotropic material parameters and to construct an electromagnetic cloak through concentric layered structure of thin, alternating layers of homogeneous isotropic materials. With proper design of the permittivity or the thickness ratio of the alternating layers, we demonstrated the low-reflection and power-flow bending properties of the proposed cloaking structure through rigorous analysis of the scattered electromagnetic fields. The proposed cloaking structure does not require anisotropy or inhomogeneity of the material constitutive parameters usually realized by metamaterials with subwavelength structured inclusions, therefore may lead to a practical path to an experimental demonstration of electromagnetic c...

  9. Dark material in the polar layered deposits on Mars

    Science.gov (United States)

    Herkenhoff, Ken

    1992-12-01

    The Martian polar layered deposits probably record periodic variations in the deposition of dust and ice caused by climate changes over the past 10 to 100 million years. The polar layered deposits appear to be the source of dark, saltating material that has been distributed over the surface of Mars, but the mechanisms by which this material is incorporated and eroded from the layered deposits is unknown. These mechanisms must be understood before the processes that formed and modified the layered deposits can be inferred and related to Martian climate changes. In summary, weathering of the Martian layered deposits by sublimation of water ice may account for the geologic relationships observed in the Martian polar regions. The non-volatile components of the layered deposits appears to consist mainly of bright red dust, with small amounts of dark dust or sand. Alternatively, dark sand-sized basaltic particles may occasionally be transported onto the layered deposits, forming thin layers. Once eroded, particles of either type may saltate to form the dark dunes found in both polar regions.

  10. Incorporating microorganisms into polymer layers provides bioinspired functional living materials

    OpenAIRE

    Gerber, Lukas C.; Koehler, Fabian M.; Grass, Robert N; Stark, Wendelin J.

    2011-01-01

    Artificial two-dimensional biological habitats were prepared from porous polymer layers and inoculated with the fungus Penicillium roqueforti to provide a living material. Such composites of classical industrial ingredients and living microorganisms can provide a novel form of functional or smart materials with capability for evolutionary adaptation. This allows realization of most complex responses to environmental stimuli. As a conceptual design, we prepared a material surface with self-cle...

  11. Sacrificial component fabrication for optimised production of micro-vascular polymer composite

    Science.gov (United States)

    Dalton, B.; Dixon, D.; McIlhagger, A.; Archer, E.

    2015-02-01

    Smart functional materials are a viable future goal for advanced applications in aerospace, space and medical applications. In this work micro-vascular polymer composite systems have been developed using sacrificial fibres produced from catalyst loaded Poly(lactic acid). The sacrificial fibres have been produced via a published technique which treated PLA in a solvent catalyst mixture of 60% Trifluoroethanol, 40% H2O dispersed with 10 wt% tin (II) oxalate catalyst. A second process of polymer extrusion of PLA using graded fill contents of tin (II) oxalate has also been developed for the up scaled production of fibres as an alternative to solution treatment. Thermal analysis (TGA) was used to compare sacrificial fibre specimens. PLA fibres produced via the polymer extrusion method outperformed solution treated fibres displaying a lower degradation onset temperature (average 25°C lower), higher degradation rates (observed through a derivative curve comparison) and lower residual catalyst content (0.67% solvent treated fibre against 0.16% extruded fibre). The continuous extrusion process is solvent free and is suitable for high volume production. This work has been carried out to fully understand the fabrication issues with sacrificial components.

  12. Contact mechanics of layered elastic materials: experiment and theory

    International Nuclear Information System (INIS)

    This paper reports an experimental and theoretical investigation of the indentation of a layered elastic solid, with special reference to the surface force apparatus (SFA). The contacting surfaces of the SFA comprise a 3-layer material: a thin mica surface layer on a thicker epoxy layer supported by a thick silica substrate. An existing finite element analysis of the deformation of ideal mica/epoxy/silica surfaces used in the SFA is adapted to compare with the experimental measurements of the variation of contact size with load, both with and without adhesion at the interface. This is in marked difference to the Johnson, Kendall and Roberts (JKR) theory for homogeneous solids. Experiments and finite element calculations were also carried out on the elastic indentation of a thin (5.5 ?m) layer of mica on a very thick layer of epoxy (>100 ?m). As input data for the calculations, the elastic moduli of the mica and epoxy were measured in separate indentation experiments. The stiffness of a layered solid can be expressed by an 'effective modulus' Ee*, which has been deduced from the experimental measurements and compared with the theoretical values with fair success. The work of adhesion is commonly measured in the SFA by observing the 'pull-off force' to separate the surfaces. The theory shows that, for a layered solid, the pull-force can vary significantly from the JKR value for a homogeneous solid. In particular, it was found that the mica surface energy, ?sv, measured by SFA experiments using crossed cylinders of mean radius R, where the materials are layered and the mica/mica adhesion is high, can vary with the pull-off force Fp according to Fp/4?R sv p/2?R, and for this particular experiment was given as ?sv = Fp/3.5 ?R as compared with ?sv = Fp/3?R for homogeneous materials

  13. Layered material characterization using ultrasonic transmission. An inverse estimation methodology.

    Science.gov (United States)

    Messineo, María G; Rus, Guillermo; Eliçabe, Guillermo E; Frontini, Gloria L

    2016-02-01

    This paper presents an inverse methodology with the aim to characterize a layered material through the identification of acoustical and mechanical properties of its layers. The framework to accomplish this objective is provided by the Inverse Problems (IPs) theory. Material characterization refers to the detection and localization of discontinuities, as well as to the identification of physical properties, in order to predict the material behaviour. In this particular case, the IP is solved in the form of a parameter estimation problem, in which the goal is the estimation of the characteristic acoustic impedance, transit time, and attenuation of each layer. These parameters are directly related to relevant material properties, such as the speed of sound, density, elastic modulus and elastic energy dissipation constants. The IP solution is obtained by minimizing a cost functional formulated as the least squares error between the waveform calculated using an equivalent model, and the measured waveform obtained from ultrasonic transmission tests. The applied methodology allowed the accurate estimation of the desired parameters in materials composed of up to three layers. As a second contribution, a power law frequency dependence of the wave attenuation was identified for several homogeneous materials, based on the same ultrasonic transmission experiments. PMID:26456278

  14. Enhanced Raman Scattering on In-Plane Anisotropic Layered Materials.

    Science.gov (United States)

    Lin, Jingjing; Liang, Liangbo; Ling, Xi; Zhang, Shuqing; Mao, Nannan; Zhang, Na; Sumpter, Bobby G; Meunier, Vincent; Tong, Lianming; Zhang, Jin

    2015-12-16

    Surface-enhanced Raman scattering (SERS) on two-dimensional (2D) layered materials has provided a unique platform to study the chemical mechanism (CM) of the enhancement due to its natural separation from electromagnetic enhancement. The CM stems from the charge interactions between the substrate and molecules. Despite the extensive studies of the energy alignment between 2D materials and molecules, an understanding of how the electronic properties of the substrate are explicitly involved in the charge interaction is still unclear. Lately, a new group of 2D layered materials with anisotropic structures, including orthorhombic black phosphorus (BP) and triclinic rhenium disulfide (ReS2), has attracted great interest due to their unique anisotropic electrical and optical properties. Herein, we report a unique anisotropic Raman enhancement on few-layered BP and ReS2 using copper phthalocyanine (CuPc) molecules as a Raman probe, which is absent on isotropic graphene and h-BN. According to detailed Raman tensor analysis and density functional theory calculations, anisotropic charge interactions between the 2D materials and molecules are responsible for the angular dependence of the Raman enhancement. Our findings not only provide new insights into the CM process in SERS, but also open up new avenues for the exploration and application of the electronic properties of anisotropic 2D layered materials. PMID:26583533

  15. Interlayer commensurability and superlubricity in rigid layered materials

    Science.gov (United States)

    Hod, Oded

    2012-08-01

    Superlubricity is a frictionless tribological state sometimes occurring in nanoscale material junctions. It is often associated with incommensurate surface lattice structures appearing at the interface. Here, by using the recently introduced registry-index concept that quantifies the registry mismatch in layered materials and reproduces their interlayer sliding energy landscape, we prove the existence of a direct relation between interlayer commensurability and wearless friction in rigid layered materials. We show that our simple and intuitive model is able to capture, down to fine details, the experimentally measured frictional behavior of a hexagonal graphene flake sliding on top of the surface of graphite. We further predict that superlubricity is expected to occur in hexagonal boron nitride as well with tribological characteristics very similar to those observed for the graphitic system. The success of our method in predicting experimental results along with its high computational efficiency marks the registry index as a promising tool for studying tribological properties of nanoscale material interfaces.

  16. Mechanics of freely-suspended ultrathin layered materials

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos-Gomez, Andres [Kavli Institute of Nanoscience, Delft University of Technology (Netherlands); Instituto Madrileno de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Madrid (Spain); Singh, Vibhor; Zant, Herre S.J. van der; Steele, Gary A. [Kavli Institute of Nanoscience, Delft University of Technology (Netherlands)

    2015-01-01

    The study of atomically thin two-dimensional materials is a young and rapidly growing field. In the past years, a great advance in the study of the remarkable electrical and optical properties of 2D materials fabricated by exfoliation of bulk layered materials has been achieved. Due to the extraordinary mechanical properties of these atomically thin materials, they also hold a great promise for future applications such as flexible electronics. For example, this family of materials can sustain very large deformations without breaking. Due to the combination of small dimensions, high Young's modulus and high crystallinity of 2D materials, they have attracted the attention of the field of nanomechanical systems as high frequency and high quality factor resonators. In this article, we review experiments on static and dynamic response of 2D materials. We provide an overview and comparison of the mechanics of different materials, and highlight the unique properties of these thin crystalline layers. We conclude with an outlook of the mechanics of 2D materials and future research directions such as the coupling of the mechanical deformation to their electronic structure. (copyright 2014 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Structure, Orientation and Stability of Lysozyme Confined in layered Materials

    OpenAIRE

    Balme, Sébastien; Guégan, Régis; Janot, Jean-Marc; Jaber, Maguy; Lepoitevin, Mathilde; Dejardin, Philippe; Bourrat, Xavier; Motelica-Heino, Mikael

    2013-01-01

    The confinement of lysozyme in 3 layered materials based on montmorillonite and lamellar double hydroxide exhibiting different surface charges was studied. The protein structure and orientation in these materials were determined by X-Ray diffraction, time resolved fluorescence and fluorescence anisotropy. For both Montmorillonite exchanged with sodium and modified with non-ionic surfactant (tri-ethylene glycol mono n-decyl ether), the lysozyme was found to be located in the interlayer space w...

  18. Epitaxial Growth of GaN-based LEDs on Simple Sacrificial Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ian Ferguson; Chris Summers

    2009-12-31

    The objective of this project is to produce alternative substrate technologies for GaN-based LEDs by developing an ALD interlayer of Al{sub 2}O{sub 3} on sacrificial substrates such as ZnO and Si. A sacrificial substrate is used for device growth that can easily be removed using a wet chemical etchant leaving only the thin GaN epi-layer. After substrate removal, the GaN LED chip can then be mounted in several different ways to a metal heat sink/reflector and light extraction techniques can then be applied to the chip and compared for performance. Success in this work will lead to high efficiency LED devices with a simple low cost fabrication method and high product yield as stated by DOE goals for its solid state lighting portfolio.

  19. Fabrication of micro/nano fluidic channels with sacrificial galvanic coupled metals

    International Nuclear Information System (INIS)

    We report a new sacrificial method for micro/nano fluidic channel fabrication by galvanic corrosion of coupled metals. Different metal combinations and etchants are investigated for achieving a high channel etching rate with very small channel cross-sections. Channels as well as channel arrays, from 50 ?m to tens of nanometres wide, are fabricated by using coupled Cr/Cu as the sacrificial layer. The channel etching rate is investigated as a function of time and width. The channel etching rate of the coupled metals is approximately 10 times faster than that of the single metal. This method is advantageous because of the high resolution, relatively high throughput, and the simplicity of the process

  20. Thin layer laser bonding using spin-on-glass materials

    International Nuclear Information System (INIS)

    We developed and characterized a new laser bonding process with a nano adhesive layer for transparent materials. The adhesive is spin-coated on a glass substrate and cured locally with a focused laser beam. The minimum viscosity of the adhesive is very low, so that a thin layer only a few hundred nanometers thick can be coated on a cover substrate. Laser irradiation from a Nd:YAG laser system with a wavelength of 1064 nm is employed as the curing source for the localized nano layer bonding process. The measured thickness of the bonding layer is in the range of 400 nm to 3 ?m. This process can be applied to the nano or micro bonding of various transparent systems such as flat panel displays, biochips, and heat-sensitive microelectronics. We present experimental results and discuss the process characteristics

  1. Carbon and titanium based layers for wood-based material

    Directory of Open Access Journals (Sweden)

    W. Kaczorowski

    2008-04-01

    Full Text Available Purpose: The main purpose of this work was to work out the technology of manufacturing carbon and titanium based layers on the surfaces of sintered carbides machining edges used in furniture industry.Design/methodology/approach: A hybrid deposition system employing DC magnetron sputtering and radio frequency plasma assisted chemical vapour deposition (RF PACVD in one reaction chamber was used to manufacture Ti:C gradient layers. For the laboratory investigation layers were deposited on sintered carbide samples. Friction coefficient and SEM EDS analysis were made. For the exploitation tests layers were deposited on the commercial sintered carbide tools widely used in furniture industry.Findings: As the result of investigation it was noticed that Ti and C based gradient layers deposited on sintered carbides surfaces seems to be a very interesting alternative for standard non modified machining tools because of they noticeably decreased friction coefficient and improved durability.Practical implications: Presented technology is dedicated for furniture industry as a layer improving the cutting properties of the machining toolsOriginality/value: Application of carbon and titanium based layers deposited by hybrid deposition method on sintered carbide cutting edges for wood and wood-based materials machining.

  2. Antitumoral materials with regenerative function obtained using a layer-by-layer technique

    Directory of Open Access Journals (Sweden)

    Ficai D

    2015-03-01

    Full Text Available Denisa Ficai,1 Maria Sonmez,1,2 Madalina Georgiana Albu,2 Dan Eduard Mihaiescu,1 Anton Ficai,1 Coralia Bleotu3 1Faculty of Applied Chemistry and Material Science, Politehnica University of Bucharest, 2Leather and Footwear Research Institute, National Research and Development Institute for Textiles and Leather, 3Stefan S Nicolau Institute of Virology, Romanian Academy, Bucharest, Romania Abstract: A layer-by layer technique was successfully used to obtain collagen/hydroxyapatite-magnetite-cisplatin (COLL/HAn-Fe3O4-CisPt, n=1–7 composite materials with a variable content of hydroxyapatite intended for use in the treatment of bone cancer. The main advantages of this system are the possibility of controlling the rate of delivery of cytostatic agents, the presence of collagen and hydroxyapatite to ensure more rapid healing of the injured bone tissue, and the potential for magnetite to be a passive antitumoral component that can be activated when an appropriate external electromagnetic field is applied. In vitro cytotoxicity assays performed on the COLL/HAn-Fe3O4-CisPt materials obtained using a layer-by layer method confirmed their antitumoral activity. Samples with a higher content of hydroxyapatite had more antitumoral activity because of their better absorption of cisplatin and consequently a higher amount of cisplatin being present in the matrices. Keywords: multifunctional materials, antitumoral activity, scaffold, bone grafts

  3. Self assembled multi-layer nanocomposite of graphene and metal oxide materials

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun; Aksay, Ilhan A; Choi, Daiwon; Kou, Rong; Nie, Zimin; Wang, Donghai; Yang, Zhenguo

    2015-04-28

    Nanocomposite materials having at least two layers, each layer consisting of one metal oxide bonded to at least one graphene layer were developed. The nanocomposite materials will typically have many alternating layers of metal oxides and graphene layers, bonded in a sandwich type construction and will be incorporated into an electrochemical or energy storage device.

  4. 10th International School of Materials Science and Technology : Intercalation in Layered Materials "Ettore Majorana"

    CERN Document Server

    1986-01-01

    This volume is prepared from lecture notes for the course "Intercalation in Layered Materials" which was held at the Ettore Majorana Centre for Scientific Culture at Erice, Sicily in July, 1986, as part of the International School of Materials Science and Tech­ nology. The course itself consisted of formal tutorial lectures, workshops, and informal discussions. Lecture notes were prepared for the formal lectures, and short summaries of many of the workshop presentations were prepared. This volume is based on these lecture notes and research summaries. The material is addressed to advanced graduate students and postdoctoral researchers and assumes a background in basic solid state physics. The goals of this volume on Intercalation in Layered Materials include an introduc­ tion to the field for potential new participants, an in-depth and broad exposure for stu­ dents and young investigators already working in the field, a basis for cross-fertilization between workers on various layered host materials...

  5. Antitumoral materials with regenerative function obtained using a layer-by-layer technique

    OpenAIRE

    Ficai, Denisa; Sonmez, Maria; Albu, Madalina Georgiana; Mihaiescu, Dan Eduard; Ficai, Anton; Bleotu, Coralia

    2015-01-01

    A layer-by layer technique was successfully used to obtain collagen/hydroxyapatite-magnetite-cisplatin (COLL/HAn-Fe3O4-CisPt, n=1–7) composite materials with a variable content of hydroxyapatite intended for use in the treatment of bone cancer. The main advantages of this system are the possibility of controlling the rate of delivery of cytostatic agents, the presence of collagen and hydroxyapatite to ensure more rapid healing of the injured bone tissue, and the potential for magnetite to be ...

  6. Ultralight Weight Optical Systems Using Nano-Layered Synthesized Materials

    Science.gov (United States)

    Clark, Natalie; Breckinridge, James

    2014-01-01

    Optical imaging is important for many NASA science missions. Even though complex optical systems have advanced, the optics, based on conventional glass and mirrors, require components that are thick, heavy and expensive. As the need for higher performance expands, glass and mirrors are fast approaching the point where they will be too large, heavy and costly for spacecraft, especially small satellite systems. NASA Langley Research Center is developing a wide range of novel nano-layered synthesized materials that enable the development and fabrication of ultralight weight optical device systems that enable many NASA missions to collect science data imagery using small satellites. In addition to significantly reducing weight, the nano-layered synthesized materials offer advantages in performance, size, and cost.

  7. Monolithic multilayer microfluidics via sacrificial molding of 3D-printed isomalt.

    Science.gov (United States)

    Gelber, Matthew K; Bhargava, Rohit

    2015-04-01

    Here we demonstrate a method for creating multilayer or 3D microfluidics by casting a curable resin around a water-soluble, freestanding sacrificial mold. We use a purpose-built 3D printer to pattern self-supporting filaments of the sugar alcohol isomalt, which we then back-fill with a transparent epoxy resin. Dissolving the sacrificial mold leaves a network of cylindrical channels as well as input and output ports. We use this technique to fabricate a combinatorial mixer capable of producing 8 combinations of two fluids in ratios ranging from 1?:?100 to 100?:?1. This approach allows rapid iteration on microfluidic chip design and enables the use of geometry and materials not accessible using conventional soft lithography. The ability to precisely pattern round channels in all three dimensions in hard and soft media may prove enabling for many organ-on-chip systems. PMID:25671493

  8. Monolithic multilayer microfluidics via sacrificial molding of 3D-printed isomalt†

    Science.gov (United States)

    Gelber, Matthew K.

    2015-01-01

    Here we demonstrate a method for creating multilayer or 3D microfluidics by casting a curable resin around a water-soluble, freestanding sacrificial mold. We use a purpose-built 3D printer to pattern self-supporting filaments of the sugar alcohol isomalt, which we then back-fill with a transparent epoxy resin. Dissolving the sacrificial mold leaves a network of cylindrical channels as well as input and output ports. We use this technique to fabricate a combinatorial mixer capable of producing 8 combinations of two fluids in ratios ranging from 1 : 100 to 100 : 1. This approach allows rapid iteration on microfluidic chip design and enables the use of geometry and materials not accessible using conventional soft lithography. The ability to precisely pattern round channels in all three dimensions in hard and soft media may prove enabling for many organ-on-chip systems. PMID:25671493

  9. Atomic layer deposited aluminum oxide barrier coatings for packaging materials

    International Nuclear Information System (INIS)

    Thin aluminum oxide coatings have been deposited at a low temperature of 80 oC on various uncoated papers, polymer-coated papers and boards and plain polymer films using the atomic layer deposition (ALD) technique. The work demonstrates that such ALD-grown Al2O3 coatings efficiently enhance the gas-diffusion barrier performance of the studied porous and non-porous materials towards oxygen, water vapor and aromas.

  10. Optical Phonon Limited High Field Transport in Layered Materials

    OpenAIRE

    Chandrasekar, Hareesh; Ganapathi, Kolla L.; Bhattacharjee, Shubhadeep; Bhat, Navakanta; Nath, Digbijoy N.

    2015-01-01

    An optical phonon limited velocity model has been employed to investigate high-field transport in a selection of layered 2D materials for both, low-power logic switches with scaled supply voltages, and high-power, high-frequency transistors. Drain currents, effective electron velocities and intrinsic cut-off frequencies as a function of carrier density have been predicted thus providing a benchmark for the optical phonon limited high-field performance limits of these materia...

  11. Study of materials for using at waste layer in repositories

    International Nuclear Information System (INIS)

    This research has an objective to characterize Brazilian clays and to implant a data base containing the information obtained form tests and suppliers. Such information will allow to buy and and to select optimum material for its utilization in the stuffing layer. Brazilian suppliers were contacted for obtaining information and samples, the various clays were tested and these tests comprehend the following: identification of the mineral constituents, determination of the compaction curve as function of the humidity, hydraulic conductivity, humidity and organic material contents, cationic exchange capacity, specific surface, and etc

  12. Atomic Layer Deposition for the Conformal Coating of Nanoporous Materials

    Directory of Open Access Journals (Sweden)

    Joe H. Satcher

    2006-07-01

    Full Text Available Atomic layer deposition (ALD is ideal for applying precise and conformal coatings over nanoporous materials. We have recently used ALD to coat two nanoporous solids: anodic aluminum oxide (AAO and silica aerogels. AAO possesses hexagonally ordered pores with diameters d∼40 nm and pore length L∼70 microns. The AAO membranes were coated by ALD to fabricate catalytic membranes that demonstrate remarkable selectivity in the oxidative dehydrogenation of cyclohexane. Additional AAO membranes coated with ALD Pd films show promise as hydrogen sensors. Silica aerogels have the lowest density and highest surface area of any solid material. Consequently, these materials serve as an excellent substrate to fabricate novel catalytic materials and gas sensors by ALD.

  13. Nanotubes Motion on Layered Materials: A Registry Perspective

    CERN Document Server

    Oz, Inbal; Itkin, Yaron; Buchwalter, Asaf; Akulov, Katherine; Hod, Oded

    2015-01-01

    At dry and clean material junctions of rigid materials the corrugation of the sliding energy landscape is dominated by variations of Pauli repulsions. These occur when electron clouds centered around atoms in adjacent layers overlap as they slide across each other. In such cases there exists a direct relation between interfacial surface (in)commensurability and superlubricity, a frictionless and wearless tribological state. The Registry Index is a purely geometrical parameter that quanti?es the degree of interlayer commensurability, thus providing a simple and intuitive method for the prediction of sliding energy landscapes at rigid material interfaces. In the present study, we extend the applicability of the Registry Index to non-parallel surfaces, using a model system of nanotubes motion on ?at hexagonal materials. Our method successfully reproduces sliding energy landscapes of carbon nanotubes on Graphene calculated using a Lennard-Jones type and the Kolmogorov-Crespi interlayer potentials. Furthermore, it...

  14. Arhaeoastronomical analysis of Levinsadovka sacrificial complex (South Russia)

    OpenAIRE

    Vodolazhskaya, Larisa; Larenok, Vera

    2013-01-01

    The article presents research data using arhaeoastronomical methods of Levinsadovka settlement sacrificial complex in Northern Black Sea coast. In this work, new method of accounting terrain elevations using topographic maps was developed in arhaeoastronomical studies. Calculations of azimuths of the sun and moon rise and set in the astronomically significant moments of the year were made and astronomical regularities in the organization of the sacrificial complex identified...

  15. Antitumoral materials with regenerative function obtained using a layer-by-layer technique.

    Science.gov (United States)

    Ficai, Denisa; Sonmez, Maria; Albu, Madalina Georgiana; Mihaiescu, Dan Eduard; Ficai, Anton; Bleotu, Coralia

    2015-01-01

    A layer-by layer technique was successfully used to obtain collagen/hydroxyapatite-magnetite-cisplatin (COLL/HAn-Fe3O4-CisPt, n=1-7) composite materials with a variable content of hydroxyapatite intended for use in the treatment of bone cancer. The main advantages of this system are the possibility of controlling the rate of delivery of cytostatic agents, the presence of collagen and hydroxyapatite to ensure more rapid healing of the injured bone tissue, and the potential for magnetite to be a passive antitumoral component that can be activated when an appropriate external electromagnetic field is applied. In vitro cytotoxicity assays performed on the COLL/HAn-Fe3O4-CisPt materials obtained using a layer-by layer method confirmed their antitumoral activity. Samples with a higher content of hydroxyapatite had more antitumoral activity because of their better absorption of cisplatin and consequently a higher amount of cisplatin being present in the matrices. PMID:25767374

  16. Materials science and technology strained-layer superlattices materials science and technology

    CERN Document Server

    Beer, Albert C; Pearsall, Thomas P

    1991-01-01

    The following blurb to be used for the AP Report and ATI only as both volumes will not appear together there.****Strained-layer superlattices have been developed as an important new form of semiconducting material with applications in integrated electro-optics and electronics. Edited by a pioneer in the field, Thomas Pearsall, this volume offers a comprehensive discussion of strained-layer superlattices and focuses on fabrication technology and applications of the material. This volume combines with Volume 32, Strained-Layer Superlattices: Physics, in this series to cover a broad spectrum of topics, including molecular beam epitaxy, quantum wells and superlattices, strain-effects in semiconductors, optical and electrical properties of semiconductors, and semiconductor devices.****The following previously approved blurb is to be used in all other direct mail and advertising as both volumes will be promoted together.****Strained-layer superlattices have been developed as an important new form of semiconducting ...

  17. KAPOOL experiments to simulate molten corium sacrificial-concrete interaction and gate opening in the EPR core catcher concept

    International Nuclear Information System (INIS)

    In future light water reactors special devices (core catchers) might be required to prevent containment failure by basement erosion after reactor pressure vessel meltthrough during a core meltdown accident. In the case of a postulated core melt down accident in the EPR (European pressurized water reactor) the ex-vessel melt shall be retained and cooled in a special compartment inside the containment to exclude significant radioactive release to the environment. After failure of the reactor pressure vessel the core melt is retained in the reactor cavity for ? 1 h to pick up late melt releases. The reactor cavity is protected by a layer of sacrificial concrete and closed by a steel gate at the bottom. After meltthrough of this gate the core melt should be distributed homogeneously in a special spreading room. A series of experiments has been performed to investigate the erosion of the sacrificial concrete as well as the gate ablation using alumina-iron thermite melts as a simulant for the core melt. Two different sorts of sacrificial concrete have been studied so far: boro-silicate glass concrete and a concrete based on Fe2O3/SiO2. Erosion velocities of the sacrificial concrete, the homogeneity of the melt front and steel gate ablation results are presented in this report. (orig.)

  18. Capacitive micro force sensors manufactured with mineral sacrificial layers

    OpenAIRE

    Fournier, Yannick; Wiedmer, Simon; Maeder, Thomas; Ryser, Peter

    2007-01-01

    In this work a prototype of micro force sensor of range ?N...mN is presented. Instead of the traditional piezoresistive strain sensing through thick-film resistors used for higher forces, a more effective principle is used: measurement of beam displacement rather than strain. A design of a cantilever sensor with capacitive electrodes, optionally coupled with an electrostatic force cancelling to achieve higher sensitivity, is proposed and discussed. The structuration of the device ...

  19. Features of heat treatment of highly porous layered materials ??????????? ???????? ????????? ???????? ?????????????? ??????????

    Directory of Open Access Journals (Sweden)

    Zhukov Aleksey Dmitrievich

    2013-05-01

    Full Text Available Effectiveness of thermal insulation products is determined by a set of criteria that can be expressed in terms of energy costs: reduction of the cost of heating (the main criterion, energy consumption in the course of construction, energy consumption in the course of production of materials having pre-set properties, and service durability of the material.On the one hand, service durability (as a property is generated in the course of material production, and on the other hand, it depends on the conditions that the material is exposed to in the course of any construction process. The same parameter affects energy-related criteria. Insulation replacement or unplanned repairs add supplementary energy costs.The manufacturing process of thermal insulation materials contemplates processing of a significant amount of non-renewable natural resources, namely, fuel combustion. Optimization of these costs is necessary and possible through appropriate organization of processes, including the process of heat treatment of products.Layered materials can improve the product performance and durability. Production and heat treatment of mineral fibers are the most energy-consuming steps of the mineral wool production. Optimization of these processes can involve significant economic effects.??????? ???????????? ????????????????? ?????????? ?????? ? ???????????? 7=0G8B5;L=>3> ?????????? ???????????????? ????????? ????????, ? ????????? ????????? ???????. ??????????? ???? ?????? ?????????? ? 2>76=0 ?? ???? ?????????? ??????????? ??????????????? ?????????, ? ?.?. ???????? ???????? ????????? ???? ???????. ? ??????????? ?????????????? ??????? ???????? ?????????? ?? ??????? ?????????? ???????? ????????? ???????????? ??????? ? ??? ???????? ?????????. ??????????? ???? ????????? ????????? ????????? ????????????? ?????????????? ???????.

  20. Ni-P-NiO electrolytic layers as anode materials

    Energy Technology Data Exchange (ETDEWEB)

    Niedbala, J. [Institute of Physics and Chemistry of Metals (IPCM), Katowice (Poland); Budniok, A. [Institute of Physics and Chemistry of Metals (IPCM), Katowice (Poland); Gierlotka, D. [Institute of Physics and Chemistry of Metals (IPCM), Katowice (Poland); Surowka, J. [Institute of Physics and Chemistry of Metals (IPCM), Katowice (Poland); Matyja, P. [Institute of Physics and Chemistry of Metals (IPCM), Katowice (Poland)

    1995-10-01

    Composite electrolytic layers were obtained on an amorphous nickel base with the addition of nickel oxide, in galvanostatic conditions at a temperature of 293 K, from a nickel-plating electrolyte in the coating containing a suspension of nickel oxide. The content of nickel oxide in the coatings depends on the conditions in which they were obtained. Using the potentiodynamic method, for these composite layers the polarisation curves of the oxygen electroevolution process from the 1 M KOH solution were determined. For comparison, curves were also plotted for copper and an amorphous Ni-P electrode. The electrodes were subjected to anode-cathode cycling in the range from the potential of oxygen evolution to the potential of hydrogen evolution. For the modified electrode materials, the characteristics of the oxygen electroevolution process were again determined. From these results the influence of the electrode material, and also the influence and advantage of preliminary modification of the surfaces of the electrodes on the process of oxygen evolution in an alkaline environment, were estimated. It was indicated that a correlation exists between the values of the exchange current of the oxygen electroevolution reaction and the electro-oxidation ability of ethanoloamine on the electrode materials studied. (orig.)

  1. First-charge instabilities of layered-layered lithium-ion-battery materials.

    Science.gov (United States)

    Croy, Jason R; Iddir, Hakim; Gallagher, Kevin; Johnson, Christopher S; Benedek, Roy; Balasubramanian, Mahalingam

    2015-10-01

    Li- and Mn-rich layered oxides with composition xLi2MnO3·(1 -x)LiMO2 enable high capacity and energy density Li-ion batteries, but suffer from degradation with cycling. Evidence of atomic instabilities during the first charge are addressed in this work with X-ray absorption spectroscopy, first principles simulation at the GGA+U level, and existing literature. The pristine material of composition xLi2MnO3·(1 -x)LiMn0.5Ni0.5O2 is assumed in the simulations to have the form of LiMn2 stripes, alternating with NiMn stripes, in the metal layers. The charged state is simulated by removing Li from the Li layer, relaxing the resultant system by steepest descents, then allowing the structure to evolve by molecular dynamics at 1000 K, and finally relaxing the evolved system by steepest descents. The simulations show that about ¼ of the oxygen ions in the Li2MnO3 domains are displaced from their original lattice sites, and form oxygen-oxygen bonds, which significantly lowers the energy, relative to that of the starting structure in which the oxygen sublattice is intact. An important consequence of the displacement of the oxygen is that it enables about ? of the (Li2MnO3 domain) Mn ions to migrate to the delithiated Li layers. The decrease in the coordination of the Mn ions is about twice that of the Ni ions. The approximate agreement of simulated coordination number deficits for Mn and Ni following the first charge with analysis of EXAFS measurements on 0.3Li2MnO3·0.7LiMn0.5Ni0.5O2 suggests that the simulation captures significant features of the real material. PMID:26334949

  2. Failure modes and materials design for biomechanical layer structures

    Science.gov (United States)

    Deng, Yan

    Ceramic materials are finding increasing usage in the area of biomechanical replacements---dental crowns, hip and bone implants, etc.---where strength, wear resistance, biocompatibility, chemical durability and even aesthetics are critical issues. Aesthetic ceramic crowns have been widely used in dentistry to replace damaged or missing teeth. However, the failure rates of ceramic crowns, especially all-ceramic crowns, can be 1%˜6% per year, which is not satisfactory to patients. The materials limitations and underlying fracture mechanisms of these prostheses are not well understood. In this thesis, fundamental fracture and damage mechanisms in model dental bilayer and trilayer structures are studied. Principle failure modes are identified from in situ experimentation and confirmed by fracture mechanics analysis. In bilayer structures of ceramic/polycarbonate (representative of ceramic crown/dentin structure), three major damage sources are identified: (i) top-surface cone cracks or (ii) quasiplasticity, dominating in thick ceramic bilayers; (iii) bottom-surface radial cracks, dominating in thin ceramic bilayers. Critical load P for each damage mode are measured in six dental ceramics: Y-TZP zirconia, glass-infiltrated zirconia and alumina (InCeram), glass-ceramic (Empress II), Porcelain (Mark II and Empress) bonded to polymer substrates, as a function of ceramic thickness d in the range of 100 mum to 10 mm. P is found independent of d for mode (i) and (ii), but has a d 2 relations for mode (iii)---bottom surface radial cracking. In trilayer structures of glass/core-ceramic/polycarbonate (representing veneer porcelain/core/dentin structures), three inner fracture origins are identified: radial cracks from the bottom surface in the (i) first and (ii) second layers; and (iii) quasiplasticity in core-ceramic layer. The role of relative veneer/core thickness, d1/d 2 and materials properties is investigated for three core materials with different modulus (114--270GPa) and strength (400--1400MPa): Y-TZP zirconia, InCeram alumina and Empress II glass-ceramic. Explicit relations for the critical loads P to produce these different damage modes in bilayer and trilayer structures are developed in terms of basic material properties (modulus E, strength, hardness H and toughness T) and geometrical variables (thickness d and contact sphere radius r). These experimentally validated relations are used to design of optimal material combinations for improved fracture resistance and to predict mechanical performance of current dental materials.

  3. Theoretical Study of Layered Oxychalcogenides as Thermoelectric Materials

    Science.gov (United States)

    Funashima, Hiroki

    2015-03-01

    In order to restrain global warming and realize a sustainable global energy system, the researches of various energy resources are done. In these various energy resources, attracted technology is thermoelectric technology. Recently Layered oxychalcogenides has interesting properties useful for new type thermoelectric materials. Firstly, from DFT and DFPT calculations, we performed the electronic structure calculation and the thermal structure calculation about layered oxychalcogenides. In addition, we calculated thermoelectric properties Blotch-Boltzmann equation, semi-classically. We indicate the mechanism behind the high power factor from calculation about the transport properties. The key to understanding the power factor is that different effective masses contribute to different transport phenomena in the crystal. The discrepancy between the effective mass for the conductivity and the thermoelectric power showed that the conductivity and thermoelectric power are conveyed by electrons with different effective masses in the Brillouin zone. In point of view the thermal conductivity ?, we discuss the electronic part ?el from Bloch-Boltzmann equations, and ?ph from DFTP calculations.

  4. Advanced Lithium Ion Battery Materials Prepared with Atomic Layer Deposition

    Science.gov (United States)

    Cavanagh, Andrew S.

    As the world consumes the dwindling supply of fossil fuels, an alternative to gasoline powered vehicles will become necessary. Lithium ion batteries (LIBs) are emerging as the dominant power source for portable electronics, and are seen as a promising energy source in the development of electric vehicles. Current LIB technology is not well suited for vehicles, increases in the energy density, power density and durability are needed before LIB are ready for widespread use in electric vehicles. LiCoO2 and graphite are the dominant cathode and anode active materials, respectively in LIBs. On the cathode side, instabilities in LiCoO 2 can lead to the deterioration of the LIB. Decomposition of electrolyte on the graphite anode surface to form a solid-electrolyte interphase (SEI) consumes lithium from the cathode resulting in a lower battery capacity. Instabilities in the in the SEI can result in catastrophic battery failure. Previous studies have employed metal oxides films, typically grown with wet chemical techniques, to stabilize LiCoO2 and mitigate the formation of the SEI on graphite. The thicknesses of films grown with wet chemical techniques was typically ˜50--1000 A. In order to achieve higher power densities, the particle size of LIB active materials is being scaled down. As active materials get smaller the mass contribution of a protective film can become a significant fraction of the total mass. Atomic layer deposition (ALD) has been used to grow ultra thin films of Al2O3 on LiCoO2 and graphite. By altering the interaction between the active material and the battery electrolyte it was possible to improve the stability of both LiCoO2 and graphite electrodes in LIBs. In the case of graphite, the Al2O3 film may be thought of as an artificial SEI. During the initial charge-discharge cycle of a LIB, the electrolyte decomposes on the anode to form the SEI. The formation of the SEI is believed to prevent further decomposition of the electrolyte on the anode surface. The SEI contains electrolyte decomposition products including Li2CO3, Li2O, LiOH, LiF and R-OLi. In order to grow a truly artificial SEI on the graphite anode, i.e. grow a film that mimics the SEI that forms during charge-discharge cycling, new ALD chemistries for the growth of Li2CO3 and LiOH have been developed. The ALD of an artificial SEI layer may limit lithium loss and improve the capacity stability during charge-discharge cycles.

  5. An innovative series of layered nanostructured aminoalkylsilica hybrid material

    Scientific Electronic Library Online (English)

    Carolina M. da, Trindade; Gabriela C., Stoll; Altair S., Pereira; Tania M. H., Costa; Edilson V., Benvenutti.

    Full Text Available Uma nova série de amostras de material híbrido à base de sílica, contendo o grupo catiônico amoniopropil ligado na forma pendente, foi obtida usando-se o método sol-gel de síntese, variando-se a razão molar entre o precursor inorgânico e o precursor orgânico. A análise termogravimétrica mostrou que [...] as amostras são termicamente estáveis até 260 ºC. Os resultados obtidos por difratometria de raios X, microscopia eletrônica de transmissão, ressonância magnética nuclear de 29Si e análise elementar são compatíveis com o modelo estrutural de camadas de silsesquioxano com distâncias basais de até 5,4 nm, contendo sílica amorfa no espaço entre as camadas. Abstract in english An innovative series of silica-based hybrid materials containing pendant cationic ammoniumpropyl groups was obtained using the sol-gel method, by varying the molar ratio of the inorganic and organic precursors. Thermogravimetric analysis showed that samples were thermally stable up to 260 ºC. Result [...] s obtained by X-ray diffractometry, transmission electron microscopy, 29Si nuclear magnetic resonance and elemental analysis were compatible with a silsesquioxane layered structural model showing basal distances up to 5.4 nm, containing amorphous silica in the interlayer space.

  6. Layer-by-layer analysis of hydrogen in structural materials on the base of reflected electron spectroscopy

    International Nuclear Information System (INIS)

    On the base of reflected electron spectroscopy the techniques of layer-by-layer analysis of hydrogen concentration in structural materials affected to thermonuclear plasma are developed. The given technique of nondestructive control may be used for analysis of thermonuclear reactor nodes and components connecting with plasma and for studying of hydrogen interaction with different materials using in hydrogen energetics. The program of statistical simulation of spectra of elastically reflected electrons from inhomogeneous media are created

  7. Sacrificial bonds and hidden length in biomaterials -- a kinetic, constitutive description of strength and toughness in bone

    CERN Document Server

    Lieou, Charles K C; Carlson, Jean M

    2013-01-01

    Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features, by providing a molecular-scale mechanism for energy dissipation. One example is in the polymeric glue connection between collagen fibrils in animal bone. In this paper, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the release of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.

  8. Carbon and titanium based layers for wood-based material

    OpenAIRE

    W. Kaczorowski; D. Batory

    2008-01-01

    Purpose: The main purpose of this work was to work out the technology of manufacturing carbon and titanium based layers on the surfaces of sintered carbides machining edges used in furniture industry.Design/methodology/approach: A hybrid deposition system employing DC magnetron sputtering and radio frequency plasma assisted chemical vapour deposition (RF PACVD) in one reaction chamber was used to manufacture Ti:C gradient layers. For the laboratory investigation layers were deposited on sinte...

  9. Catechol-based layer-by-layer assembly of composite coatings: a versatile platform to hierarchical nano-materials.

    Science.gov (United States)

    Wang, C X; Braendle, A; Menyo, M S; Pester, C W; Perl, E E; Arias, I; Hawker, C J; Klinger, D

    2015-08-21

    Inspired by the marine mussel's ability to adhere to surfaces underwater, an aqueous catechol-based dip coating platform was developed. Using a catechol-functionalized polyacrylamide binder in combination with inorganic nanoparticles enables the facile fabrication of robust composite coatings via a layer-by-layer process. This modular assembly of well-defined building blocks provides a versatile alternative to electrostatic driven approaches with layer thickness and refractive indices being readily tunable. The platform nature of this approach enables the fabrication of hierarchically ordered nano-materials such as Bragg stacks. PMID:26151660

  10. Evaluation of proton conductivity by random walk approach in MOFs and layered materials.

    Czech Academy of Sciences Publication Activity Database

    Konale, M.S.; Lin, C.H.; Patil, D.; Zima, Vít?zslav; Shimakawa, K.; Svoboda, Jan

    Mulhouse : Univ. Haute Alsace, 2014. [International Workshop on Layered Materials /5./. 27.08.2014-29.08.2014, Mulhouse] R&D Projects: GA ?R(CZ) GA14-13368S Institutional support: RVO:61389013 Keywords : layered materials * metal organic framework * impedance analysis Subject RIV: CA - Inorganic Chemistry

  11. A rational design of cosolvent exfoliation of layered materials by directly probing liquid–solid interaction

    OpenAIRE

    Halim, Udayabagya; Zheng, Chu Ran; Chen, Yu; Lin, Zhaoyang; Jiang, Shan; Cheng, Rui; Huang, Yu; Duan, Xiangfeng

    2013-01-01

    Exfoliation of layered materials such as graphite and transition metal dichalcogenides into mono- or few-layers is of significant interest for both the fundamental studies and potential applications. Here we report a systematic investigation of the fundamental factors governing the liquid exfoliation process and the rational design of a cosolvent approach for the exfoliation of layered materials. We show that Young’s equation can be used to predict the optimal cosolvent concentration for the ...

  12. Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

    Energy Technology Data Exchange (ETDEWEB)

    Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher; Lane, George Hamilton; Morgan, Dane; Nevin, Josh; Cedar, Gerbrand; Persson, Kristin Aslaug; Eaglesham, David

    2015-11-05

    Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqeuous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

  13. Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

    Energy Technology Data Exchange (ETDEWEB)

    Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher; Lane, George Hamilton; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin Aslaug; Eaglesham, David

    2015-10-27

    Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqeuous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

  14. Shrinking device realized by using layered structures of homogeneous isotropic materials

    International Nuclear Information System (INIS)

    We propose the practical realization of a shrinking device by using layered structures of homogeneous isotropic materials. By mimicking the shrinking device with concentric alternating thin layers of isotropic dielectrics, the permittivity and the permeability in each isotropic layer can be properly determined from the effective medium theory in order to achieve the shrinking effect. The device realized by multilayer coating with dielectrics is validated by TE wave simulation, and good shrinking performance is demonstrated with only a few layers of homogeneous isotropic materials. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  15. TiO?/ZnO inner/outer double-layer hollow fibers for improved detection of reducing gases.

    Science.gov (United States)

    Katoch, Akash; Kim, Jae-Hun; Kim, Sang Sub

    2014-12-10

    TiO2/ZnO double-layer hollow fibers (DLHFs) are proposed as a superior sensor material in comparison to regular single-layer hollow fibers (HFs) for the detection of reducing gases. DLHFs were synthesized on sacrificial polymer fibers via atomic layer deposition of a first layer of TiO2 followed by a second layer of ZnO and by a final thermal treatment. The inner TiO2 receives electrons from the ZnO outer layer, which becomes more resistive due to the significant loss of electrons. This highly resistive ZnO layer partially regains its original resistivity when exposed to reducing gases such as CO, thus enabling more resistance variation in DLHFs. DLHFs are a novel material compared to HFs and can be successfully employed to fabricate chemical sensors for the accurate detection of reducing gases. PMID:25379680

  16. Layered Hydroxide–Porphyrin Hybrid Materials: Synthesis, Structure, and Properties.

    Czech Academy of Sciences Publication Activity Database

    Demel, Jan; Lang, Kamil

    2012-01-01

    Ro?. 2012, ?. 32 (2012), s. 5154-5164. ISSN 1434-1948 R&D Projects: GA ?R GAP207/10/1447 Institutional support: RVO:61388980 Keywords : layered compounds * intercalations * porphyrinoids * phthalocyanines * singlet oxygen Subject RIV: CA - Inorganic Chemistry Impact factor: 3.120, year: 2012

  17. Layer-by-layer polyelectrolyte deposition: a mechanism for forming biocomposite materials

    OpenAIRE

    Tan, YerPeng; Yildiz, Umit Hakan; Wei, Wei; Waite, J. Herbert; Miserez, Ali

    2013-01-01

    Complex coacervates prepared from poly-Aspartic acid (polyAsp) and poly-L-Histidine (polyHis) were investigated as models of the metastable protein phases used in the formation of biological structures such as squid beak. When mixed, polyHis and polyAsp form coacervates whereas poly-L-Glutamic acid (polyGlu) forms precipitates with polyHis. Layer-by-layer (LbL) structures of polyHis-polyAsp on gold substrates were compared with those of precipitate-forming polyHis-polyGlu by monitoring with i...

  18. High quality 2D crystals made by anodic bonding: a general technique for layered materials

    International Nuclear Information System (INIS)

    Anodic bonding of nanolayers is an easy technique based on a simple apparatus, which has already proven successful in application in the fabrication of high quality graphene. Here we demonstrate its extension to the fabrication of high quality nanolayers from several layered materials. The strengths of this technique are its high throughput rate and ease of application. All fabrication parameters are controllable and need to be determined carefully. We report optimal parameters found for nine layered materials. In general, using optimal parameters results in high quality 2D layers, in most cases much larger than those obtained by ‘Scotch tape’ microcleavage, with higher yields and which are easily transferable to other substrates. Moreover the samples obtained are clean and the good optical contrast of these layers on the glass substrate makes their identification very easy. This is thus the technique of choice for making nanolayers in the laboratory from any layered material. (paper)

  19. Three-dimensional textures and defects of soft material layering revealed by thermal sublimation

    Science.gov (United States)

    Yoon, Dong Ki; Kim, Yun Ho; Kim, Dae Seok; Oh, Seong Dae; Smalyukh, Ivan I.; Clark, Noel A.; Jung, Hee-Tae

    2013-01-01

    Layering is found and exploited in a variety of soft material systems, ranging from complex macromolecular self-assemblies to block copolymer and small-molecule liquid crystals. Because the control of layer structure is required for applications and characterization, and because defects reveal key features of the symmetries of layered phases, a variety of techniques have been developed for the study of soft-layer structure and defects, including X-ray diffraction and visualization using optical transmission and fluorescence confocal polarizing microscopy, atomic force microscopy, and SEM and transmission electron microscopy, including freeze-fracture transmission electron microscopy. Here, it is shown that thermal sublimation can be usefully combined with such techniques to enable visualization of the 3D structure of soft materials. Sequential sublimation removes material in a stepwise fashion, leaving a remnant layer structure largely unchanged and viewable using SEM, as demonstrated here using a lamellar smectic liquid crystal. PMID:24218602

  20. Fabrication of sacrificial anode cathodic protection through casting method

    International Nuclear Information System (INIS)

    Aluminum is one of the few metals that can be cast by all of the processes used in casting metals. These processes consist of die casting, permanent mold casting, sand casting (green sand and dry sand), plaster casting, investment casting, and continuous casting. Other processes such as lost foam, squeeze casting, and hot isostatic pressing are also used. Permanent mold casting method was selected in which used for fabricating of sacrificial anode cathodic protection. This product was ground for surface finished and fabricated in the cylindrical form and reinforced with carbon steel at a center of the anode. (Author)

  1. Intercalation of push-pull molecules into layered materials bearing acidic functionalities.

    Czech Academy of Sciences Publication Activity Database

    Zima, Vít?zslav; Melánová, Klára; Svoboda, Jan; Beneš, L.; Knotek, P.

    Mulhouse : Univ. Hazte Alsace, 2014. [International Workshop on Layered Materials /5./. 27.08.2014-29.08.2014, Mulhouse] Institutional support: RVO:61389013 Keywords : zirconium phosphate * phosphate * intercalation Subject RIV: CA - Inorganic Chemistry

  2. Standard test method for laboratory evaluation of magnesium sacrificial anode test specimens for underground applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    1.1 This test method covers a laboratory procedure that measures the two fundamental performance properties of magnesium sacrificial anode test specimens operating in a saturated calcium sulfate, saturated magnesium hydroxide environment. The two fundamental properties are electrode (oxidation potential) and ampere hours (Ah) obtained per unit mass of specimen consumed. Magnesium anodes installed underground are usually surrounded by a backfill material that typically consists of 75 % gypsum (CaSO4·2H2O), 20 % bentonite clay, and 5 % sodium sulfate (Na2SO4). The calcium sulfate, magnesium hydroxide test electrolyte simulates the long term environment around an anode installed in the gypsum-bentonite-sodium sulfate backfill. 1.2 This test method is intended to be used for quality assurance by anode manufacturers or anode users. However, long term field performance properties may not be identical to property measurements obtained using this laboratory test. Note 1—Refer to Terminology G 15 for terms used ...

  3. Tribological and Wear Properties of Multi-Layered Materials

    Directory of Open Access Journals (Sweden)

    V. Bria

    2011-09-01

    Full Text Available The usage of fabrics as reinforcements in composites is spreading due to fabrics’ properties. The use of fabrics allows obtaining of sinuous surfaces, for instance, unlike the use of prepregs. Using fabrics as reinforcements it is also possible to obtain laminate-like materials having the same matrix in all their volume. In the case of pre-pregs usage always it is necessary to discuss about the bonding between individual plies. For this study eight materials were formed. The forming method consisted in placing the pre-polymer imbued fabric pieces into a mould to obtain plates of composites. Two types of fabric were used: one simple type of untwisted tows of carbon fibres and the second one simple type of alternated untwisted tows of carbon and aramide fibres. Both fabrics were prepared in order to ensure the matrix adherence. The polymer matrix is realised from epoxy system EPIPHEN RE 4020 / EPIPHEN DE 4020 filled with clay and talc in equal amounts of 5% (weight ratio. The use of clay and talc were meant to improve the thermal dimensional stability of final materials. Tribological properties of formed materials were studied using pin-on-disk method with steel disk and pins made of materials. Both orientation of reinforcement fibres relative to friction direction were taken into account. Results are encouraging further studies in order to identify the best solution of forming a multi-component material with more than one designable property.

  4. An advanced tunnel oxide layer process for 65 nm NOR floating-gate flash memories

    Science.gov (United States)

    Chiu, Shengfen; Xu, Yue; Ji, Xiaoli; Liao, Yiming; Wu, Fuwei; Yan, Feng

    2015-10-01

    An advanced tunnel oxide layer process for 65 nm NOR-type floating-gate flash memory is proposed to improve tunnel oxide quality by an additive sacrificial oxide layer growth. The sacrificial oxide layer process effectively controls the thickness variation of tunnel oxide and improves the flatness of the SiO2/Si interface across the active area. The interface traps’ generation during program/erase cycling of flash cells is found to be reduced, and the reliability property is significantly improved as compared to flash cells without the sacrificial oxide layer process. The technology is applicable to further scaled floating-gate flash memories.

  5. A multifluid mix model for the layered incompressible materials

    International Nuclear Information System (INIS)

    In this paper, a model for the unstable mixing of n parallel or concentric incompressible fluid layers is proposed. The approach to constructing this model is pairwise, based on a known two incompressible fluid mixing model. The problem complexity increases significantly in going from two to three fluids, but the increase in complexity is relatively small thereafter. We present a detailed study of the n=3 problem, which displays all of the difficult modeling issues applicable to arbitrary n?3 while still being reasonably tractable.

  6. A multifluid mix model for the layered incompressible materials

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, B L; Sharp, D H [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Glimm, J; Yu, Y [Department of Applied Mathematics and Statistics, University at Stony Brook, Stony Brook, NY 11794-3600 (United States)], E-mail: bcheng@lanl.gov

    2008-12-15

    In this paper, a model for the unstable mixing of n parallel or concentric incompressible fluid layers is proposed. The approach to constructing this model is pairwise, based on a known two incompressible fluid mixing model. The problem complexity increases significantly in going from two to three fluids, but the increase in complexity is relatively small thereafter. We present a detailed study of the n=3 problem, which displays all of the difficult modeling issues applicable to arbitrary n{>=}3 while still being reasonably tractable.

  7. Is self-sacrificial competitive altruism primarily a male activity?

    Science.gov (United States)

    McAndrew, Francis T; Perilloux, Carin

    2012-01-01

    This study explored the basis of self-sacrificial prosocial behavior in small groups. Seventy-eight undergraduates (39M, 39F) filled out a thirty-item personality scale and then participated in a "group problem-solving study" in which the monetary success of a three-person group depended upon one of its members volunteering to endure pain (a cold stressor test) and inconvenience (being soaked in a dunk tank). There were 13 groups consisting of two females and one male, and 13 groups consisting of two males and one female. Across groups, the behavior of the altruist was judged to be more costly, challenging, and important and he/she was liked better, rewarded with more money, and preferred as a future experimental partner. Groups containing two males showed more evidence of competition to become altruists than groups containing two females, and personality traits were more effective predictors of altruistic behavior in males than in females. We conclude that competition between males and "showing off" are key factors in triggering self-sacrificial altruistic behavior. PMID:22833848

  8. Geologic Evolution of Mars' North Polar Layered Deposits and Related Materials from Mars Odyssey THEMIS

    Science.gov (United States)

    Vasavada, A. R.; Richardson, M. I.; Byrne, S.; Ivanov, A. B.; Christensen, P. R.

    2003-01-01

    The presence of a thick sequence of horizontal layers of ice-rich material at Mars north pole, dissected by troughs and eroding at its margins, is undoubtedly telling us something about the evolution of Mars climate we just don't know what yet. The North Polar Layered Deposits (NPLD) most likely formed as astronomically driven climate variations led to the deposition of conformable, areally extensive layers of ice and dust over the polar region. More recently, the balance seems to have fundamentally shifted to net erosion, as evidenced by the many troughs within the NPLD and the steep, arcuate scarps present near its margins, both of which expose layering.

  9. Radionuclide separations using pillared layered materials. Final report

    International Nuclear Information System (INIS)

    The objective of this project is to prepare an all inorganic strontium specific sorbent or ion exchanger for the removal of highly alkaline nuclear waste solutions. A series of clays and layered titanates were pillared and calcined to convert their essentially two dimensional structure to three dimensional porous structures with high surface areas. The pillaring agents were alumina, zirconia, chromia and silica based. The pillared clays, particularly those containing Zr pillars, achieved moderate (Kd as high at 13,700 ml/g with V:m = 28) selectivities for Sr2+. In contrast, the silica pillared titanates showed exceptional affinities for Sr2+ with Kd values in excess of 100,000 ml/g in 5M NaNO3 + 1M NaOH. These latter results suggest a more detailed study of the pillared titanates in the presence of simulants closely resembling real waste solutions

  10. Scanning tunnelling microscopy observations of biomolecules on layered materials.

    Science.gov (United States)

    Jungblut, H; Campbell, S A; Giersig, M; Müller, D J; Lewerenz, H J

    1992-01-01

    Scanning tunnelling microscopy (STM) has been performed on the reverse transcriptases of the human immunodeficiency virus (HIV-1) and the moloney murine leukaemia virus (MuLV). The biological molecules are adsorbed on n-type semiconducting MoTe2. The p66 (66 kD) subunit of the RT of HIV-1 is imaged by STM. Both STM and processed transmission electron microscopy (TEM) data show a spherical and horseshoe-like shape of external diameter ca. 65 A, depending on the angle of observation. The STM results show a larger diameter which is related to the curvature radius of the tip of the probing needle. The RTs of HIV-1 and MuLV exhibit a circular hole of ca. 20 A diameter in accordance with structure predictions and functioning considerations. The surface-molecule interaction is discussed in terms of the electronic properties of the semiconductor surface including the influence of small defect sites at the layered crystal surface. PMID:1285040

  11. Sacrificial adhesive bonding: a powerful method for fabrication of glass microchips

    Science.gov (United States)

    Lima, Renato S.; Leão, Paulo A. G. C.; Piazzetta, Maria H. O.; Monteiro, Alessandra M.; Shiroma, Leandro Y.; Gobbi, Angelo L.; Carrilho, Emanuel

    2015-08-01

    A new protocol for fabrication of glass microchips is addressed in this research paper. Initially, the method involves the use of an uncured SU-8 intermediate to seal two glass slides irreversibly as in conventional adhesive bonding-based approaches. Subsequently, an additional step removes the adhesive layer from the channels. This step relies on a selective development to remove the SU-8 only inside the microchannel, generating glass-like surface properties as demonstrated by specific tests. Named sacrificial adhesive layer (SAB), the protocol meets the requirements of an ideal microfabrication technique such as throughput, relatively low cost, feasibility for ultra large-scale integration (ULSI), and high adhesion strength, supporting pressures on the order of 5?MPa. Furthermore, SAB eliminates the use of high temperature, pressure, or potential, enabling the deposition of thin films for electrical or electrochemical experiments. Finally, the SAB protocol is an improvement on SU-8-based bondings described in the literature. Aspects such as substrate/resist adherence, formation of bubbles, and thermal stress were effectively solved by using simple and inexpensive alternatives.

  12. Crack propagation in the vicinity of the interface in layered materials.

    Czech Academy of Sciences Publication Activity Database

    Šestáková, Lucie; Náhlík, Luboš; Huta?, Pavel; Knésl, Zden?k

    Plze? : University of West Bohemia, 2008 - (Adámek, V.). s. 1-2 ISBN 978-80-7043-712-4. [Computational Mechanics 2008. 03.11.2008-05.11.2008, Ne?tiny] R&D Projects: GA ?R GD106/05/H008; GA AV ?R(CZ) KJB200410803 Institutional research plan: CEZ:AV0Z20410507 Keywords : crack * bi-material interface * stability criteria * layered materials Subject RIV: JL - Materials Fatigue, Friction Mechanics

  13. Estimation of the critical stress for failure of layered composite materials.

    Czech Academy of Sciences Publication Activity Database

    Náhlík, Luboš; Šestáková, Lucie; Huta?, Pavel; Knésl, Zden?k

    Beijing : Beijing Institute of Technology, 2008. s. 103-103. [International Workshop on Computational Mechanics of Materials /18./. 07.10.2008-10.10.2008, Beijing] R&D Projects: GA ?R GA106/08/1409; GA AV ?R(CZ) KJB200410803 Institutional research plan: CEZ:AV0Z20410507 Keywords : interface * layered materials * crack stability * critical stress * ceramic composites Subject RIV: JL - Materials Fatigue, Friction Mechanics

  14. Living bacterial sacrificial porogens to engineer decellularized porous scaffolds.

    Science.gov (United States)

    Xu, Feng; Sridharan, BanuPriya; Durmus, Naside Gozde; Wang, ShuQi; Yavuz, Ahmet Sinan; Gurkan, Umut Atakan; Demirci, Utkan

    2011-01-01

    Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D) hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types. PMID:21552485

  15. Optimisation of the material properties of indium tin oxide layers for use in organic photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Doggart, P.; Bristow, N.; Kettle, J., E-mail: j.kettle@bangor.ac.uk [School of Electronic Engineering, Bangor University, Dean St., Bangor, Gwynedd, Wales LL57 1UT (United Kingdom)

    2014-09-14

    The influence of indium tin oxide [(In{sub 2}O{sub 3}:Sn), ITO] material properties on the output performance of organic photovoltaic (OPV) devices has been modelled and investigated. In particular, the effect of altering carrier concentration (n), thickness (t), and mobility (?{sub e}) in ITO films and their impact on the optical performance, parasitic resistances and overall efficiency in OPVs was studied. This enables optimal values of these parameters to be calculated for solar cells made with P3HT:PC{sub 61}BM and PCPDTBT:PC{sub 71}BM active layers. The optimal values of n, t and ?{sub e} are not constant between different OPV active layers and depend on the absorption spectrum of the underlying active layer material system. Consequently, design rules for these optimal values as a function of donor bandgap in bulk-heterojunction active layers have been formulated.

  16. A new type of clear orthodontic retainer incorporating multi-layer hybrid materials

    Science.gov (United States)

    Ahn, Hyo-Won; Kim, Kyung A

    2015-01-01

    Clear thermoplastic retainers have been widely used in daily orthodontics; however, they have inherent limitations associated with thermoplastic polymer materials such as dimensional instability, low strength, and poor wear resistance. To solve these problems, we developed a new type of clear orthodontic retainer that incorporates multi-layer hybrid materials. It consists of three layers; an outer polyethylenterephthalate glycol modified (PETG) hard-type polymer, a middle thermoplastic polyurethane (TPU) soft-type polymer, and an inner reinforced resin core. The resin core improves wear resistance and mechanical strength, which prevent unwanted distortion of the bucco-palatal wall of the retainer. The TPU layer absorbs impact and the PETG layer has good formability, optical qualities, fatigue resistance, and dimensional stability, which contributes to increased support from the mandibular dentition, and helps maintain the archform. This new type of vacuum-formed retainer showed improved mechanical strength and rate of water absorption. PMID:26445722

  17. Improvement of Cylindrical Cloak by Layered Structure of Homogeneous Isotropic Materials

    OpenAIRE

    Ding, Jun; Liu, Yang; Chenjiang GUO; Xu, Qian

    2009-01-01

    The perfect cylindrical cloak requires three spatial variant material parameters, which is very difficult to realize in practice [Science 312, 1780 (2006)]. The approach of realizing the electromagnetic cloaking by concentric layered structures instead of using the metamaterial was presented [Optics Express, Vol. 15, No. 18 (2007)]. We use the concentric layered structures to realize a simplified cylindrical cloak with improved parameters and an ideal cylindrical cloak with spatially invarian...

  18. Heterostructures based on two-dimensional layered materials and their potential applications

    KAUST Repository

    Li, Ming-Yang

    2015-12-04

    The development of two-dimensional (2D) layered materials is driven by fundamental interest and their potential applications. Atomically thin 2D materials provide a wide range of basic building blocks with unique electrical, optical, and thermal properties which do not exist in their bulk counterparts. The van der Waals interlayer interaction enables the possibility to exfoliate and reassemble different 2D materials into arbitrarily and vertically stacked heterostructures. Recently developed vapor phase growth of 2D materials further paves the way of directly synthesizing vertical and lateral heterojunctions. This review provides insights into the layered 2D heterostructures, with a concise introduction to preparative approaches for 2D materials and heterostructures. These unique 2D heterostructures have abundant implications for many potential applications.

  19. Analysis of Photothermal Characterization of Layered Materials: Design of Optimal Experiments

    Science.gov (United States)

    Cole, Kevin D.

    2003-01-01

    In this paper numerical calculations are presented for the steady-periodic temperature in layered materials and functionally-graded materials to simulate photothermal methods for the measurement of thermal properties. No laboratory experiments were performed. The temperature is found from a new Green s function formulation which is particularly well-suited to machine calculation. The simulation method is verified by comparison with literature data for a layered material. The method is applied to a class of two-component functionally-graded materials and results for temperature and sensitivity coefficients are presented. An optimality criterion, based on the sensitivity coefficients, is used for choosing what experimental conditions will be needed for photothermal measurements to determine the spatial distribution of thermal properties. This method for optimal experiment design is completely general and may be applied to any photothermal technique and to any functionally-graded material.

  20. Identification of new pillared-layered carbon nitride materials at high pressure

    OpenAIRE

    Ashkan Salamat; Malek Deifallah; Raul Quesada Cabrera; Furio Corà; McMillan, Paul F.

    2013-01-01

    The compression of the layered carbon nitride C6N9H3·HCl was studied experimentally and with density functional theory (DFT) methods. This material has a polytriazine imide structure with Cl(-) ions contained within C12N12 voids in the layers. The data indicate the onset of layer buckling accompanied by movement of the Cl(-) ions out of the planes beginning above 10-20?GPa followed by an abrupt change in the diffraction pattern and c axis spacing associated with formation of a new interlayer ...

  1. Two-dimensional nanosheets produced by liquid exfoliation of layered materials.

    OpenAIRE

    Coleman, JN; Lotya, M; O'Neill, A; Bergin, SD; King, PJ; Khan, U.; Young, K.; Gaucher, A; De, S; Smith, RJ; Shvets, IV; Arora, SK; Stanton, G; Kim, HY; Lee, K.

    2011-01-01

    If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS(2), WS(2), MoSe(2), MoTe(2), TaSe(2), NbSe(2), NiTe(2), BN, and Bi(2)Te(3) can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exf...

  2. Efficiency of a Multi-Soil-Layering System on Wastewater Treatment Using Environment-Friendly Filter Materials

    OpenAIRE

    Ho, Chia-Chun; Wang, Pei-Hao

    2015-01-01

    The multi-soil-layering (MSL) system primarily comprises two parts, specifically, the soil mixture layer (SML) and the permeable layer (PL). In Japan, zeolite is typically used as the permeable layer material. In the present study, zeolite was substituted with comparatively cheaper and more environmentally friendly materials, such as expanded clay aggregates, oyster shells, and already-used granular activated carbon collected from water purification plants. A series of indoor tests indicated ...

  3. Investigation of helium ions release processes from surface layer of lithium containing materials of fusion reactors

    International Nuclear Information System (INIS)

    Full text: The lithium-containing materials are considered as materials, which can be used to solve many pressing issues of creating fusion reactor. Each of these materials has its own specific advantages and disadvantages, but they have in common the ability of realization of the nuclear reactions on lithium isotopes to produce tritium and helium. All the data on the release of helium ions from the surface layer of lithium-containing materials under reactor irradiation were analyzed. To explain the effect of the intensive release of helium ions the experiments with different cooling rates of lead-lithium eutectics were performed

  4. Development of a Biocompatible Layer-by-Layer Film System Using Aptamer Technology for Smart Material Applications

    Directory of Open Access Journals (Sweden)

    Amanda Foster

    2014-05-01

    Full Text Available Aptamers are short, single-stranded nucleic acids that fold into well-defined three dimensional (3D structures that allow for binding to a target molecule with affinities and specificities that can rival or in some cases exceed those of antibodies. The compatibility of aptamers with nanostructures such as thin films, in combination with their affinity, selectivity, and conformational changes upon target interaction, could set the foundation for the development of novel smart materials. In this study, the development of a biocompatible aptamer-polyelectrolyte film system was investigated using a layer-by-layer approach. Using fluorescence microscopy, we demonstrated the ability of the sulforhodamine B aptamer to bind its cognate target while sequestered in a chitosan-hyaluronan film matrix. Studies using Ultraviolet-visible (UV-Vis spectrophotometry also suggest that deposition conditions such as rinsing time and volume play a strong role in the internal film interactions and growth mechanisms of chitosan-hyaluronan films. The continued study and development of aptamer-functionalized thin films provides endless new opportunities for novel smart materials and has the potential to revolutionize the field of controlled release.

  5. In Situ XRD Investigations on Structural Change of P2-Layered Materials during Electrochemical Sodiation/Desodiation

    DEFF Research Database (Denmark)

    Jung, Young Hwa; Johnsen, Rune E.; Christiansen, Ane Sælland; Norby, Poul; Kim, Do Kyung

    2014-01-01

    Sodium layered oxides (NaxMO2) are attractive as positive electrode materials for rechargeable sodium-ion batteries (SIBs) due to high capacity, fast ionic diffusion and simple synthetic process. O3-layered lithium compounds have led successful commercialization of current lithium-ion batteries; as a result, rich experiences for structural studies of O3-layered compounds have been accumulated over the past decades. For sodium layered oxides, however, P2-layered compounds have been reported for b...

  6. Mixed-layered bismuth--oxygen--iodine materials for capture and waste disposal of radioactive iodine

    Energy Technology Data Exchange (ETDEWEB)

    Krumhansl, James L; Nenoff, Tina M

    2015-01-06

    Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

  7. Elastic properties of a material composed of alternating layers of negative and positive Poisson's ratio

    International Nuclear Information System (INIS)

    The theory of elasticity predicts a variety of phenomena associated with solids that possess a negative Poisson's ratio. The fabrication of metamaterials with a 'designed' microstructure that exhibit a Poisson's ratio approaching the thermodynamic limits of 1/2 and -1 increases the likelihood of realising these phenomena for applications. In this work, we investigate the properties of a layered composite, with alternating layers of materials with negative and positive Poisson's ratio approaching the thermodynamic limits. Using the finite element method to simulate uniaxial loading and indentation of a free standing composite, we observed an increase in the resistance to mechanical deformation above the average value of the two materials. Even though the greatest increase in stiffness is gained as the thermodynamic limits are approached, a significant amount of added stiffness can be attained, provided that the Young's modulus of the negative Poisson's ratio material is not less than that of the positive Poisson's ratio material

  8. Atomistic simulation of nanoporous layered double hydroxide materials and their properties. I. Structural modeling

    Science.gov (United States)

    Kim, Nayong; Kim, Yongman; Tsotsis, Theodore T.; Sahimi, Muhammad

    2005-06-01

    An atomistic model of layered double hydroxides, an important class of nanoporous materials, is presented. These materials have wide applications, ranging from adsorbents for gases and liquid ions to nanoporous membranes and catalysts. They consist of two types of metallic cations that are accommodated by a close-packed configuration of OH- and other anions in a positively charged brucitelike layer. Water and various anions are distributed in the interlayer space for charge compensation. A modified form of the consistent-valence force field, together with energy minimization and molecular dynamics simulations, is utilized for developing an atomistic model of the materials. To test the accuracy of the model, we compare the vibrational frequencies, x-ray diffraction patterns, and the basal spacing of the material, computed using the atomistic model, with our experimental data over a wide range of temperature. Good agreement is found between the computed and measured quantities.

  9. Atomistic simulation of nanoporous layered double hydroxide materials and their properties. I. Structural modeling.

    Science.gov (United States)

    Kim, Nayong; Kim, Yongman; Tsotsis, Theodore T; Sahimi, Muhammad

    2005-06-01

    An atomistic model of layered double hydroxides, an important class of nanoporous materials, is presented. These materials have wide applications, ranging from adsorbents for gases and liquid ions to nanoporous membranes and catalysts. They consist of two types of metallic cations that are accommodated by a close-packed configuration of OH- and other anions in a positively charged brucitelike layer. Water and various anions are distributed in the interlayer space for charge compensation. A modified form of the consistent-valence force field, together with energy minimization and molecular dynamics simulations, is utilized for developing an atomistic model of the materials. To test the accuracy of the model, we compare the vibrational frequencies, x-ray diffraction patterns, and the basal spacing of the material, computed using the atomistic model, with our experimental data over a wide range of temperature. Good agreement is found between the computed and measured quantities. PMID:15974768

  10. Steady State Crack Propagation in Layered Material Systems Displaying Visco-plastic Behaviour

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau

    2012-01-01

    The steady state fracture toughness of elastic visco-plastic materials is studied numerically, using both a conventional and a higher order model. Focus is on the combined effect of strain hardening, strain gradient hardening and strain rate hardening on cracking in layered material systems, and predictions for the crack tip shielding ratio is brought forward. Included is a novel procedure for extracting information on the rate-independent toughness without approaching this numerically cumbersome limit.

  11. Multi-layered Poly-Dimethylsiloxane As A Non-Hermetic Packaging Material For Medical MEMS

    OpenAIRE

    Lachhman, S.; Zorman, C.A.; Ko, W. H.

    2012-01-01

    Poly-dimethylsiloxane (PDMS) is an attractive material for packaging implantable biomedical microdevices owing to its biocompatibility, ease in application, and bio-friendly mechanical properties. Unfortunately, devices encapsulated by PDMS lack the longevity for use in chronic implant applications due to defect-related moisture penetration through the packaging layer. This paper describes an effort to improve the performance of PDMS as packaging material by constructing the encapsulant from ...

  12. Fatigue crack growth and fracture mechanics analysis of a working roll surface layer material

    OpenAIRE

    M. Drobne; Vuherer, T.; I. Samardži?; S Glodež

    2014-01-01

    Fatigue crack growth and fracture mechanics analysis of a working roll surface layer material is presented in this paper. The research is done on a hot strip mill working roll where High Chromium Steel is used for roll’s shell material. To obtain corresponding parameters, a rectangular single edge notched bend specimens – SENB, according to standard BS 7448, were used. The fatigue crack growth analysis was done on a resonant testing machine with use of special crack gauges, while for fracture...

  13. Crack propagation in the vicinity of bi-material interface: application to multi-layer pipes.

    Czech Academy of Sciences Publication Activity Database

    Šestáková, Lucie; Náhlík, Luboš; Huta?, Pavel; Knésl, Zden?k

    Brno : ÚFM AV ?R Brno, 2008, s. 15-20. ISBN 978-80-254-3492-5. [Víceúrov?ový design pokrokových materiál? /4./. Brno (CZ), 04.12.2008-05.12.2008] R&D Projects: GA ?R GD106/05/H008; GA AV ?R(CZ) KJB200410803 Institutional research plan: CEZ:AV0Z20410507 Keywords : bi-material interface * crack propagation * multi-layer pipes Subject RIV: JL - Materials Fatigue, Friction Mechanics

  14. Effect of biomolecules adsorption on oxide layers developed on metallic materials used in cooling water systems

    International Nuclear Information System (INIS)

    This thesis was carried out in the frame of the BIOCOR ITN European project, in collaboration with the industrial partner RSE S.p.A. (Italy). Metallic materials commonly used in cooling systems of power plants may be affected by bio-corrosion induced by biofilm formation. The objective of this work was to study the influence of biomolecules adsorption, which is the initial stage of biofilm formation, on the electrochemical behaviour and the surface chemical composition of three metallic materials (70Cu-30Ni alloy, 304L stainless steel and titanium) in seawater environments. In a first step, the interactions between a model protein, the bovine serum albumin (BSA), and the surface of these materials were investigated. Secondly, tightly bound (TB) and loosely bound (LB) extracellular polymeric substances (EPS), that play a fundamental role in the different stages of biofilm formation, maturation and maintenance, were extracted from Pseudomonas NCIMB 2021 marine strain, and their effects on oxide layers were also evaluated. For that purpose, electrochemical measurements (corrosion potential E(corr) vs time, polarization curves and electrochemical impedance spectroscopy (EIS)) performed during the very first steps of oxide layers formation (1 h immersion time) were combined to surface analysis by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ions mass spectrometry (ToF-SIMS). Compared to 70Cu-30Ni alloy in static artificial seawater (ASW) without biomolecules, for which a thick duplex oxide layer (outer redeposited Cu2O layer and inner oxidized nickel layer) is shown, the presence of BSA, TB EPS and LB EPS leads to a mixed oxide layer (oxidized copper and nickel) with a lower thickness. In the biomolecules-containing solutions, this oxide layer is covered by an adsorbed organic layer, mainly composed of proteins. A model is proposed to analyse impedance data obtained at E(corr). The results show a slow-down of the anodic reaction in the presence of biomolecules (BSA, TB EPS and LB EPS), and a corrosion inhibition effect by LB EPS and to a lesser extent by BSA. No detrimental effect is evidenced with TB EPS. On the other hand, the effect of TB EPS and BSA on the passivation behaviour of Ti in ASW and of 304L stainless steel in chloride-free solution was studied. From EIS data, resistivity profiles within oxide films can be plotted. For both materials, oxide layers are more protective with BSA and less protective with TB EPS compared to the solution without biomolecules. At last, biomolecules induce no significant differences in oxide layer composition and thickness. (author)

  15. A fluorescent, photochromic and thermochromic trifunctional material based on a layered metal-viologen complex.

    Science.gov (United States)

    Wan, Fang; Qiu, Li-Xia; Zhou, Liang-Liang; Sun, Yan-Qiong; You, Yi

    2015-11-14

    The azide anion as an energy acceptor and an electron donor has been introduced into a metal-viologen compound to form a 2D layered viologen-based trifunctional material, which exhibits the rare discolored function of reversible photochromism and thermochromism. Interestingly, its fluorescence can be switched by visible light irradiation and heating in air. PMID:26445888

  16. Material properties of smectic layers and the formation of modulated and cubic smectic phases

    OpenAIRE

    Helfrich, W

    1987-01-01

    Models are proposed for a modulated smectic phase (Ã) and the cubic smectics (D and a nameless phase) that are based on the material properties of the single smectic layer such as curvature elasticity and boundary (or inversion wall) energies. They furnish criteria for the transformation of regular smectics (A, C) into these phases.

  17. NiW/TiO{sub x} composite layers as cathode material for hydrogen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Rashkov, R.; Arnaudova, M.; Avdeev, G. [Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Acad. G. Bonchev Str. bl.11 (Bulgaria); Zielonka, A. [Forschungsinstitut fuer Edelmetalle und Metallchemie, 73525 Schwaebisch Gmuend, Katharinenstrasse 17 (Germany); Jannakoudakis, P.; Jannakoudakis, A.; Theodoridou, E. [Institute of Physical Chemistry, Aristotle University, 54124 Thessaloniki (Greece)

    2009-03-15

    NiW + TiO{sub x} composite layers were obtained in electrolyte solutions containing nickel sulphamate with high concentration of W and nonstoichiometric titanium oxides particles (TiO{sub x}). The co-deposition of NiW layers with TiO{sub x} particles was carried out under potentiostatic conditions on pristine and oxidized carbon fibers by stirring. Comparatively, NiW layers were obtained under the same experimental conditions. The morphology of the deposits was examined by means of scanning electron microscopy (SEM). Secondary crystallization of NiW layers on the surface of the embedded Ti oxides particles was observed. The structure and the chemical states of the elements in the deposits were illustrated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. Electrochemical impedance spectroscopy (EIS) was used to study the electrocatalytic activity of these materials for the hydrogen evolution reaction (HER) in acid solution. The results showed that NiW + TiO{sub x} layers on oxidized carbon fiber electrodes possess the highest electrocatalytic activity for HER compared with NiW + TiO{sub x} layers on nonoxidized carbon fiber electrodes and NiW layers on oxidized carbon fiber electrodes. (author)

  18. Monitoring the Startup of a Sacrificial Concrete Sewer for Odor Control

    DEFF Research Database (Denmark)

    Nielsen, Asbjørn Haaning; Vollertsen, Jes

    2014-01-01

    The use of a sacrificial concrete sewer for controlling sulphide-related odour downstream of a pressure sewer was investigated in this study. The investigated sewer is located in a rural catchment and is intended to alleviate odour problems downstream of a small diameter pressure sewer with extended retention time. For the purpose of the study, a 50-m long sacrificial concrete gravity sewer was constructed using a high alkalinity concrete pipe. The monitoring campaign reported in this paper cove...

  19. Fabrication of scalable and structured tissue engineering scaffolds using water dissolvable sacrificial 3D printed moulds

    DEFF Research Database (Denmark)

    Mohanty, Soumyaranjan; Larsen, Layla Bashir; Trifol Guzman, Jon; Szabo, Peter; Burri, Harsha Vardhan Reddy; Canali, Chiara; Dufva, Martin; Emnéus, Jenny; Wolff, Anders

    2015-01-01

    One of the major challenges in producing large scale engineered tissue is the lack of ability to create large highly perfused scaffolds in which cells can grow at a high cell density and viability. Here, we explore 3D printed polyvinyl alcohol (PVA) as a sacrificial mould in a polymer casting process. The PVA mould network defines the channels and is dissolved after curing the polymer casted around it. The printing parameters determined the PVA filament density in the sacrificial structure and t...

  20. Thermophysical Properties of Mars' North Polar Layered Deposits and Related Materials from Mars Odyssey THEMIS

    Science.gov (United States)

    Vasavada, A. R.; Richardson, M. I.; Byrne, S.; Ivanov, A. B.; Christensen, P. R.

    2003-01-01

    The presence of a thick sequence of horizontal layers of ice-rich material at Mars north pole, dissected by troughs and eroding at its margins, is undoubtedly telling us something about the evolution of Mars climate [1,2] we just don t know what yet. The North Polar Layered Deposits (NPLD) most likely formed as astronomically driven climate variations led to the deposition of conformable, areally extensive layers of ice and dust over the polar region. More recently, the balance seems to have fundamentally shifted to net erosion, as evidenced by the many troughs within the NPLD and the steep, arcuate scarps present near its margins, both of which expose layering. We defined a number of Regions of Interest ROI) for THEMIS to target as part of the Mars Odyssey Participating Scientist program. We use these THEMIS data in order to understand the morphology and color/thermal properties of the NPLD and related materials over relevant (i.e., m to km) spatial scales. We have assembled color mosaics of our ROIs in order to map the distribution of ices, the different layered units, dark material, and underlying basement. The color information from THEMIS is crucial for distinguishing these different units which are less distinct on Mars Orbiter Camera images. We wish to understand the nature of the marginal scarps and their relationship to the dark material. Our next, more ambitious goal is to derive the thermophysical properties of the different geologic materials using THEMIS and Mars Global Surveyor Thermal Emission Spectrometer TES) data.

  1. Struvite precipitation and phosphorus removal using magnesium sacrificial anode.

    Science.gov (United States)

    Kruk, Damian J; Elektorowicz, Maria; Oleszkiewicz, Jan A

    2014-04-01

    Struvite precipitation using magnesium sacrificial anode as the only source of magnesium is presented. High-purity magnesium alloy cast anode was found to be very effective in recovery of high-quality struvite from water solutions and from supernatant of fermented waste activated sludge from a wastewater treatment plant that does not practice enhanced biological phosphorus removal. Struvite purity was strongly dependent on the pH and the electric current density. Optimum pH of the 24 mM phosphorus and 46 mM ammonia solution (1:1.9 P:N ratio) was in the broad range between 7.5 and 9.3, with struvite purity exceeding 90%. Increasing the current density resulted in elevated struvite purity. No upper limits were observed in the studied current range of 0.05-0.2 A. Phosphorus removal rate was proportional to the current density and comparable for tests with water solutions and with the supernatant from fermented sludge. The highest P-removal rate achieved was 4.0 mg PO4-P cm(-2) h(-1) at electric current density of 45 A m(-2). Initial substrate concentrations affected the rate of phosphorus removal. The precipitated struvite accumulated in bulk liquid with significant portions attached to the anode surface from which regular detachment occurred. PMID:24387911

  2. Finite element for beams having segmented active constrained layers with frequency-dependent viscoelastic material properties

    Science.gov (United States)

    Lesieutre, George A.; Lee, Usik

    1997-05-01

    A finite element for planar beams with active constrained layer damping treatments is presented. Features of this non- shear locking element include a time-domain viscoelastic material model, and the ability to readily accommodate segmented (i.e. non-continuous) constraining layers. These features are potentially important in active control applications: the frequency-dependent stiffness and damping of the viscoelastic material directly affects system modal frequencies and damping; the high local damping of the viscoelastic layer can result in complex vibration modes and differences in the relative phase of vibration between points; and segmentation, an effective means of increasing passive damping in long-wavelength vibration modes, affords multiple control inputs and improved performance in an active constrained layer application. The anelastic displacement fields (ADF) method is used to implement the viscoelastic material model, enabling the straightforward development of time-domain finite elements. The performance of the finite element is verified through several sample modal analyses, including proportional-derivative control based on discrete strain sensing. Because of phasing associated with mode shapes, control using a single continuous ACL can be destabilizing. A segmented ACL is more robust than the continuous treatment, in that the damping of modes at least up to the number of independent patches is increased by control action.

  3. Identification of new pillared-layered carbon nitride materials at high pressure.

    Science.gov (United States)

    Salamat, Ashkan; Deifallah, Malek; Cabrera, Raul Quesada; Corà, Furio; McMillan, Paul F

    2013-01-01

    The compression of the layered carbon nitride C6N9H3 · HCl was studied experimentally and with density functional theory (DFT) methods. This material has a polytriazine imide structure with Cl(-) ions contained within C12N12 voids in the layers. The data indicate the onset of layer buckling accompanied by movement of the Cl(-) ions out of the planes beginning above 10-20 GPa followed by an abrupt change in the diffraction pattern and c axis spacing associated with formation of a new interlayer bonded phase. The transition pressure is calculated to be 47 GPa for the ideal structures. The new material has mixed sp(2)-sp(3) hybridization among the C and N atoms and it provides the first example of a pillared-layered carbon nitride material that combines the functional properties of the graphitic-like form with improved mechanical strength. Similar behavior is predicted to occur for Cl-free structures at lower pressures. PMID:23817211

  4. Comparison of some coating techniques to fabricate barrier layers on packaging materials

    International Nuclear Information System (INIS)

    Atomic layer deposition (ALD), electron beam evaporation, magnetron sputtering and a sol-gel method were used to deposit thin aluminum oxide coatings onto two different fiber-based packaging materials of commercial board grades coated with synthetic and biodegradable polymers. Significant decreases in both the water vapor and oxygen permeation rates were observed. With each technique the barrier performance was improved. However, among the techniques tested ALD was found to be most suitable. Our results moreover revealed that biodegradable polylactic acid-coated paperboard with a 25-nm thick layer of aluminum oxide grown by ALD on top of it showed promising barrier characteristics against water vapor and oxygen.

  5. Restricted equivalence of paired epsilon-negative and mu-negative layers to a negative phase-velocity material ({\\em alias} left-handed material)

    OpenAIRE

    Lakhtakia, A.; Krowne, C. M.

    2003-01-01

    The time-harmonic electromagnetic responses of (a) a bilayer made of an epsilon-negative layer and a mu-negative layer, and (b) a single layer of a negative phase-velocity material are compared. Provided all layers are electrically thin, a restricted equivalence between (a) and (b) exists. The restricted equivalence depends on the linear polarization state and the transverse wavenumber. Implications for perfect lenses and parallel-plate waveguides are considered.

  6. Metallic layered composite materials produced by explosion welding: Structure, properties, and structure of the transition zone

    Science.gov (United States)

    Mal'tseva, L. A.; Tyushlyaeva, D. S.; Mal'tseva, T. V.; Pastukhov, M. V.; Lozhkin, N. N.; Inyakin, D. V.; Marshuk, L. A.

    2014-10-01

    The structure, morphology, and microhardness of the transition zone in multilayer metallic composite joints are studied, and the cohesion strength of the plates to be joined, the mechanical properties of the formed composite materials, and fracture surfaces are analyzed. The materials to be joined are plates (0.1-1 mm thick) made of D16 aluminum alloy, high-strength maraging ZI90-VI (03Kh12N9K4M2YuT) steel, BrB2 beryllium bronze, and OT4-1 titanium alloy. Composite materials made of different materials are shown to be produced by explosion welding. The dependence of the interface shape (smooth or wavelike) on the physicomechanical properties of the materials to be joined is found. The formation of a wavelike interface is shown to result in the formation of intense-mixing regions in transition zones. Possible mechanisms of layer adhesion are discussed.

  7. Crystallographic dependence of the lateral undercut wet etch rate of Al0.5In0.5P in diluted HCl for III-V sacrificial release

    DEFF Research Database (Denmark)

    Ansbæk, Thor; Semenova, Elizaveta

    2013-01-01

    The authors investigated the use of InAlP as a sacrificial layer lattice-matched to GaAs when diluted hydrochloric acid is used for sacrificial etching. They show that InAlP can be used to fabricate submicrometer air gaps in micro-opto-electro-mechanical systems and that a selectivity toward GaAs larger than 500 is achieved. This selectivity enables fabrication control of the nanometer-size structures required in photonic crystal and high-index contrast subwavelength grating structures. The crystallographic dependence of the lateral etch rate in InAlP is shown to be symmetric around the ?110? directions where an etch rate of 0.5??m/min is obtained at 22?°C in HCl:2H2O. Since the etch rate in the ?100? directions exceeds by ten times that of the ?110? directions, InAlP may be used in sacrificial release of high-aspect ratio structures. Free-hanging structures with length to air-gap aspect ratios above 600 are demonstrated by use of critical point drying following the sacrificial etch.

  8. 3D-printed silicate porous bioceramics using a non-sacrificial preceramic polymer binder.

    Science.gov (United States)

    Zocca, A; Elsayed, H; Bernardo, E; Gomes, C M; Lopez-Heredia, M A; Knabe, C; Colombo, P; Günster, J

    2015-06-01

    Silicate bioceramics possess an excellent bioactivity; however, shaping them into complex geometries is still challenging. Therefore, this paper aims to present a new strategy for the shaping of a bioglass-ceramic with controlled geometry and properties starting from a glass powder combined with a preceramic polymer, i.e. a silicon resin, and reactive fillers. The powder-based three-dimensional (3D)-printing of wollastonite (CaSiO3)-based silicate bioceramic parts was demonstrated in this work. The resin plays a dual role, as it not only acts as a non-sacrificial binder for the filler powders in the printing process but it also reacts with the fillers to generate the desired bioceramic phases. The mechanical and physical properties, i.e. ball-on-three-balls test, density, porosity and morphology, were evaluated in 3D-printed discs. These samples possessed a total porosity around 64 vol% and a biaxial flexural strength around 6 MPa. The raw materials used in this work also enabled the 3D-printing of scaffolds possessing a designed multi-scale porosity, suitable bioceramic phase assemblage and a compressive strength of 1 MPa (for cylindrical scaffolds with total porosity ~80 vol%). Solubility in TRIS/HCl and in vitro assays, i.e. viability, cytotoxicity and apoptosis assays, were also performed. In vitro tests indicated good cell viability and no cytotoxicity effect on the cells. PMID:26000907

  9. Heat transfer from an internally heated liquid layer

    International Nuclear Information System (INIS)

    This paper is concerned with the development of methods for analyzing the postaccident heat removal characteristics of a fast breeder reactor, specifically, the problem of predicting melting rates of a structural material heated from above by a horizontal layer of molten fuel. There are two important phases of postaccident behavior to which this work particularly applies: penetration of the reactor vessel by molten fuel, and penetration of sacrificial protective barriers. The paper describes the results of analyses of the available experimental correlations of heat transfer in horizontal fluid layers with uniform internal heat sources and develops means to apply the information to analyses of postaccident heat removal in fast reactors. Data and correlations are presented which relate upward and downward heat fluxes from an internally heated liquid layer to the heat generation rate in and thickness of the heated layer and the thermophysical properties of the heated layer. The paper also describes the results of experiments undertaken to assess the feasibility of using microwave heating of liquids to simulate decay heating by fission products in molten fuel. Experimental data are reported on the melting attack on simulant structural materials including paraffin wax and naphthalene by simulant fuel layers, glycerine and ethylene glycol, internally heated by microwave energy. Results are explained in terms of the newly developed correlations for layer heat transfer. Examples of the application to prediction of melting rates of steel structures by mixed-oxide fuel, internally heated by radioactive decay, are described

  10. Electrochemical reactions of layered niobate material as novel anode for sodium ion batteries

    Science.gov (United States)

    Nakayama, Hideki; Nose, Masafumi; Nakanishi, Shinji; Iba, Hideki

    2015-08-01

    The electrochemical performances of layered niobium oxide materials were investigated for the first time as novel anode active materials for the sodium-ion battery. The layered niobate with the formula KNb3O8 was synthesized by a solid-state reaction and has been evaluated as an anode electrode by a cyclic voltammetry technique and galvanostatic charge/discharge tests. The crystal structure of KNb3O8 contains the NbO6 octahedral units and potassium alkali-metal ions interlayer to form the layered structure. KNb3O8 has a redox reaction around 1 V vs. Na/Na+ and has a reversible capacity of 104 mAh/g corresponding to the 1.7 Na+ insertion/extraction in the KNb3O8 structure. The Nb K-edge X-ray absorption near edge structure (XANES) shows that the Nb oxidation state is converted from Nb5+ to Nb4+ during the Na+ insertion stage, and reversibly recovered to Nb5+ during the Na+ extraction stage. This is the first report that the layered niobate of KNb3O8 reversibly reacts with Na+ at the potential around 1 V vs. Na/Na+ via the Nb5+/4+ redox reaction.

  11. DETERMINATION OF MECHANICAL STRENGTH OF SAME MATERIAL DOUBLE-LAYER RECTANGULAR TABLETS

    Directory of Open Access Journals (Sweden)

    ISMAEL HARTRIAN

    2000-07-01

    Full Text Available The mechanical strength of same material composite beams of Avicel PHI02, Starch 1500 and Emcompress were assessed by three-point bending test. To provide an improved method of comparing the strength of the tablets, the tensile strength of the specimens was calculated by equations based on stress analysis. Increasing the compaction pressure led to decrease of the porosity of the compacted tablets while the overall mass of the composite tablets were kept constant. Meanwhile, the values of fracture load and strengths (including tensile and shear raised by increasing the compaction pressure. However, when the lower layer was compacted twice, the value of tensile stress of the lower layer was more than its value in a single compacted tablet with the same material. This observation was attributed to the extent of the reduction of porosity during compaction of the single tablets which raised in their tensile strength values.

  12. New layered metal oxides as positive electrode materials for room-temperature sodium-ion batteries

    Science.gov (United States)

    Mu, Lin-Qin; Hu, Yong-Sheng; Chen, Li-Quan

    2015-03-01

    In order to achieve better Na storage performance, most layered oxide positive electrode materials contain toxic and expensive transition metals Ni and/or Co, which are also widely used for lithium-ion batteries. Here we report a new quaternary layered oxide consisting of Cu, Fe, Mn, and Ti transition metals with O3-type oxygen stacking as a positive electrode for room-temperature sodium-ion batteries. The material can be simply prepared by a high-temperature solid-state reaction route and delivers a reversible capacity of 94 mAh/g with an average storage voltage of 3.2 V. This paves the way for cheaper and non-toxic batteries with high Na storage performance. Project supported by the National Natural Science Foundation of China (Grant Nos. 51222210 and 11234013) and the One Hundred Talent Project of the Chinese Academy of Sciences.

  13. Layer-dependent wall properties of abdominal aortic aneurysms: Experimental study and material characterization.

    Science.gov (United States)

    Sassani, Sophia G; Kakisis, John; Tsangaris, Sokrates; Sokolis, Dimitrios P

    2015-09-01

    Mechanical testing and in-depth characterization of the abdominal aortic aneurysm wall from fifteen patients undergoing open surgery was performed to establish the layer-dependent tissue properties that are non-available in the literature. Quantitative microscopic evaluation was performed to identify the spatial organization of collagen-fiber network. Among a number of candidate models, the four-fiber family (microstructure-motivated) model, especially that including dispersions of fiber angles about the main directions, was superior to the Fung- and Gasser-type models in the fitting quality allowed, though it presented a practical difficulty in parameter estimation, so that an analysis was conducted aiding the identification of a more specific diagonal- and circumferential-fiber family model for all three layers. The adventitia was stiffer and stronger than the other layers, owing to its increased collagen content, and its contribution to the response of the intact wall was augmented being under greater residual tension than the media, whereas the intima was under residual compression. All layers were stiffer circumferentially than longitudinally, due to preferential collagen arrangement along that axis. The histologically-guided material characterization of layered wall presented herein is expected to assist clinical decision, by developing reliable criteria to predict the rupture risk of abdominal aortic aneurysms, and optimize endovascular interventions. PMID:26011656

  14. Synthesis and characterisation of gas sensor materials obtained from Pt/Zn/Al layered double hydroxides

    OpenAIRE

    GHIOTTI, Giovanna; MORANDI, Sara; PRINETTO, Federica

    2006-01-01

    We reported about the possibility to employ Zn(Al)O and Pt–Zn(Al)O mixed oxides obtained from layered double hydroxides (LDH) as gas sensor materials. We prepared the samples following two different routes: a classical co-precipitation and a sol–gel method. After structural and textural characterisation, the powders were studied by FT-IR spectroscopy under different controlled atmospheres at different temperatures. Eventually, conductance measurements were performed on thick films of these...

  15. Polycrystalline SiC as source material for the growth of fluorescent SiC layers

    DEFF Research Database (Denmark)

    Kaiser, M.; Hupfer, T.

    2013-01-01

    Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport method. The grain influence on the growth rate of fluorescent SiC layers grown by a sublimation epitaxial process is discussed in respect of surface kinetics.

  16. Analysis and design of viscoelastic materials for active constrained layer damping treatments

    Science.gov (United States)

    Liao, Wei-Hsin; Wang, Kon-Well

    1996-05-01

    This paper is concerned with the investigations of viscoelastic material (VEM) effects on active constrained layer (ACL) based structures. Specific interests are on how the VEM parameters will influence the passive damping ability and the active action transmissibility in an ACL configuration. The study has identified the VEM parameter regions that will provide the best active-passive hybrid actions. This research also developed guidelines to synthesize ACL structures that will outperform both the purely passive and active systems.

  17. Fatigue crack growth and fracture mechanics analysis of a working roll surface layer material

    Directory of Open Access Journals (Sweden)

    M. Drobne

    2014-10-01

    Full Text Available Fatigue crack growth and fracture mechanics analysis of a working roll surface layer material is presented in this paper. The research is done on a hot strip mill working roll where High Chromium Steel is used for roll’s shell material. To obtain corresponding parameters, a rectangular single edge notched bend specimens – SENB, according to standard BS 7448, were used. The fatigue crack growth analysis was done on a resonant testing machine with use of special crack gauges, while for fracture mechanics parameters the electro–mechanical testing machine was used.

  18. Development of N-layer materials for SNS junction and SQUID applications

    International Nuclear Information System (INIS)

    Materials characteristics including water reactivity, oxygen loss, electromigration of oxide ions, and interfacial reactivity problems have plagued attempts to produce reliable and reproducible cuprate SNS superconductor junctions. In an effort to solve some of these formidable problems, new N-layer compounds from the family of R1-xCaxBa2-yLayCu3-zMzO7-? (R = Y, Gd and Pr; M = Co, Ni and Zn; 0 2Cu3O7-? phase and the modified materials exhibit enhanced durability properties. The compounds have been utilized to make both SNS junctions and SQUID devices

  19. Examination of a phase change material's layer efficiency when applied in a building's envelope

    Science.gov (United States)

    Briola, Maria

    2015-02-01

    This paper consists of both a theoretical and an experimental study of phase change materials. Specifically, the theoretical part starts with a reference to the need of using new energy-saving technologies with phase change materials and an introduction to thermal energy storage. Then, follows the presentation of the properties of these materials and the methods of their measurement, their classification in categories as well as the methods of simulating PCM. After that, the paper analyzes the most common PCM applications in buildings. The experimental part examines the efficiency of a phase change material (PCM) layer, embedded in a south, east, west and north-oriented wall which is charged externally by the sun, in relation to various parameters. Summing up, this paper brings together the results and final conclusions drawn by the experimental study, presenting several recommendations for future work.

  20. A proposed method to determine the adherence for the layers made out of thermal sprayed materials on internal cylindrical surfaces

    Directory of Open Access Journals (Sweden)

    Adrian V. Petrica

    2005-10-01

    Full Text Available The paper presents an investigation method for the adherence of the layers made out of thermal sprayed materials on the inner surface of some parts. The base material is made of steel. The deposition procedure was the electric arc thermal spraying, flame spraying asnd plasma spraying and the filler materials used were: copper, brass and aluminum bronze. The proposed method analyses the adherence force by measuring the shear unit fracture stress of the deposited layers.

  1. Biomacromolecule immobilization and self-assembled monolayer chemistry on atomic layer deposited metal oxide materials

    Science.gov (United States)

    Bergkvist, Magnus

    2009-10-01

    Many biotechnology applications involve interfacing proteins, DNA and other macromolecules to non-biological material surfaces acting as supports. Support materials employed for this purpose span the periodic table and range from polymeric membranes/hydrogels to metals and ceramics, for example gold and hydroxyapatite. Lab-on-a-chip and other sensing/detection applications based on lithography and semiconductor technology typically rely on alkanethiol and organosilane chemistry to immobilize biological material to gold and silica. While successful in many instances, organosilane chemistry offers limited options for orthogonal chemistry and often results in multilayer film buildup. Self-assembly on gold is straight forward but gold is often undesirable from a device perspective. Recent developments in atomic layer deposition (ALD) allow fabrication of high quality thin films of alumina and high-k oxide materials that are compatible with clean room operations and are interesting emerging materials for integrated optical, electronic and biological applications. Here we will show alternative self-assembly chemistries on ALD materials for biological immobilization than those used on gold/silica and also demonstrate direct biological interfacing to high-K materials for potential use in bioscreening and detection.

  2. Layered oxychalcogenide in the Bi–Cu–O–Se system as good thermoelectric materials

    International Nuclear Information System (INIS)

    Since 2010, we have evidenced the very promising thermoelectric properties of layered oxychalcogenides, with parent compound BiCuSeO, which could be used in thermoelectric conversion systems in the 300–600 °C temperature range. These materials, that were first studied in the early 2000s for their optoelectronic properties, exhibit thermoelectric figure of merit values around 1.4 at 650 °C, which makes them the best lead- or tellurium-free p-type thermoelectric materials ever reported to date. In this paper, we will review the chemical, structural and physical properties of this family of materials, with an emphasis on the links between crystal structure, electronic structure and functional properties. (paper)

  3. Vertically stacked multi-heterostructures of layered materials for logic transistors and complementary inverters.

    Science.gov (United States)

    Yu, Woo Jong; Li, Zheng; Zhou, Hailong; Chen, Yu; Wang, Yang; Huang, Yu; Duan, Xiangfeng

    2013-03-01

    Graphene has attracted considerable interest for future electronics, but the absence of a bandgap limits its direct applicability in transistors and logic devices. Recently, other layered materials such as molybdenum disulphide (MoS(2)) have been investigated to address this challenge. Here, we report the vertical integration of multi-heterostructures of layered materials for the fabrication of a new generation of vertical field-effect transistors (VFETs) with a room temperature on-off ratio > 10(3) and a high current density of up to 5,000 A cm(-2). An n-channel VFET is created by sandwiching few-layer MoS(2) as the semiconducting channel between a monolayer graphene sheet and a metal thin film. This approach offers a general strategy for the vertical integration of p- and n-channel transistors for high-performance logic applications. As an example, we demonstrate a complementary inverter with a larger-than-unity voltage gain by vertically stacking graphene, Bi(2)Sr(2)Co(2)O(8) (p-channel), graphene, MoS(2) (n-channel) and a metal thin film in sequence. The ability to simultaneously achieve a high on-off ratio, a high current density and a logic function in such vertically stacked multi-heterostructures can open up possibilities for three-dimensional integration in future electronics. PMID:23241535

  4. Suitability of Structural Aluminium Profiles as Sacrificial Anode for Carbon Steel

    Directory of Open Access Journals (Sweden)

    Iyiola O. OTUNNIYI

    2012-11-01

    Full Text Available The life of low carbon steels in many small scale structures can be remarkably prolonged by complementary sacrificial anode cathodic protection (SACP but for constraints in availability of specialty anodes. Suitability of commonly available structural aluminium profiles as sacrificial anodes for low carbon steel has been investigated. Three different profiles were studied. Bare and coated steel samples were found to migrate clearly too cathodic potential regimes when coupled with the press-finish BS1470:6000 AlMgSi series alloy in a chloride medium. No weight loss was observed for the coated steel sample, while the aluminium profile showed dissolution. This alloy, commonly available in press-finish profiles for structural purposes, is therefore recommendable as sacrificial anodes for complementary SACP of low carbon steel structures under atmospheric or aqueous exposures.

  5. he sacrificial emplotment of national identity. Pádraic Pearse and the 1916 Easter uprising

    Directory of Open Access Journals (Sweden)

    Patrick Colm Hogan

    2014-06-01

    Full Text Available A sense of national identification remains amorphous and inert unless it is cognitively structured and motivationally oriented. Perhaps the most consequential way of structuring and orienting nationalism is through emplotment (organizing in the form of a story. Emplotment commonly follows one of a few cross-culturally recurring genres. In nationalist contexts, the heroic genre—treating military conflict, loss or potential loss, and reasserted sovereignty–is the default form. However, this default may be overridden in particular circumstances. When social devastation precludes heroic achievement, a sacrificial emplotment—treating collective sin, punishment, sacrifice, and redemption—is often particularly salient. Earlier work has examined cases of sacrificial emplotment in its most extreme varieties (treating Hitler and Gandhi. The following essay considers a more ordinary case, the sacrificial nationalism of the prominent Irish anti-colonial revolutionary, Pádraic Pearse, as represented in his plays.

  6. Friction of sheared granular layers: Role of particle dimensionality, surface roughness, and material properties

    Science.gov (United States)

    Knuth, Matthew; Marone, Chris

    2007-03-01

    We report on laboratory experiments designed to investigate three fundamental deformation mechanisms for frictional shear of granular fault gouge: sliding, rolling, and dilation. Mechanisms were isolated by shearing layers composed of rods in geometric configurations that resulted in one-dimensional, two-dimensional, and rolling-only particle interactions. Results of digital video are presented with measurements of friction and strain to illuminate the distribution of shear and the relationship between particle motions and friction. The double-direct-shear configuration was used with boundary conditions of constant layer normal stress (1 MPa) and controlled shear loading rate (10 ?m/s) with initial layer thickness of 6 mm. Layers were sheared in a servo-hydraulic testing machine at room temperature (22°C) and relative humidity (5 to 10%). Three materials were studied: alloy 260 brass, dried semolina pasta, and hardwood dowels, with particle diameters of 1.59 mm, 1.86 mm, and 2.06 mm, respectively. Pasta layers had mean sliding friction coefficients of 0.24, 0.11, and 0.02 in 2-D, 1-D, and rolling configurations, respectively. Layers of brass rods had average friction coefficients of 0.23, 0.15, and 0.01, respectively, in 2-D, 1-D, and rolling configurations; and the wood samples exhibited friction values of 0.18, 0.19, and 0.09, respectively. Evolution of strength during shear correlated strongly with the displacement derivative of layer thickness. SEM images document the role of surface finish on frictional properties. Rapid reorientations of particles correspond to stick-slip stress drops and may be related to the collapse and reformation of granular force chains. We find a systematic relationship between the strength of granular layers and (1) the surface roughness of particles and (2) the number of particle contact dimensions. Our data provide important insights on the mechanics of granular fault gouge and constraints on the fundamental parameters used in numerical models of tectonic faulting.

  7. Tuning the Transport Properties of Layered Materials for Thermoelectric Applications using First-Principles Calculations

    KAUST Repository

    Saeed, Yasir

    2014-05-11

    Thermoelectric materials can convert waste heat into electric power and thus provide a way to reduce the dependence on fossil fuels. Our aim is to model the underlying materials properties and, in particular, the transport as controlled by electrons and lattice vibrations. The goal is to develop an understanding of the thermoelectric properties of selected materials at a fundamental level. The structural, electronic, optical, and phononic properties are studied in order to tune the transport, focusing on KxRhO2, NaxRhO2, PtSb2 and Bi2Se3. The investigations are based on density functional theory as implemented in the all electron linearized augmented plane wave plus local orbitals WIEN2k and pseudo potential Quantum-ESPRESSO codes. The thermoelectric properties are derived from Boltzmann transport theory under the constant relaxation time approximation, using the BoltzTraP code. We will discuss first the changes in the electronic band structure under variation of the cation concentration in layered KxRhO2 in the 2H phase and NaxRhO2 in the 3R phase. We will also study the hydrated phase. The deformations of the RhO6 octahedra turn out to govern the thermoelectric properties, where the high Seebeck coefficient results from ”pudding mold" bands. We investigate the thermoelectric properties of electron and hole doped PtSb2, which is not a layered material but shares “pudding mold" bands. PtSb2 has a high Seebeck coefficient at room temperature, which increases significantly under As alloying by bandgap opening and reduction of the lattice thermal conductivity. Bi2Se3 (bulk and thin film) has a larger bandgap then the well-known thermoelectric material Bi2Te3, which is important at high temperature. The structural stability, electronic structure, and transport properties of one to six quintuple layers of Bi2Se3 will be discussed. We also address the effect of strain on a single quintuple layer by phonon band structures. We will analyze the electronic and transport properties of Tl-doped Bi2Se3 under strain, focusing on the giant Rashba spin splitting (Tl doping breaks the inversion symmetry in Bi2Se3) and its dependence on biaxial tensile and compressive strain.

  8. Effect of Dissimilar Material Layers on Collision Process Between Projectile and Two-Dimensional Ordered Particle Packing

    Science.gov (United States)

    Nishida, Masahiro; Tanaka, Koichi

    2009-06-01

    The dynamic response of a two-dimensional ordered particle packing subjected to the impact of a spherical projectile was investigated experimentally as well as numerically by the discrete element method (DEM). The main component of this particle packing is mono-size nylon spheres of 6.36 mm diameter (1/4 inch diameter), arranged uniformly, vertically and two-dimensionally in 9 layers of 37 (or 36) spheres each, in a rectangular container. A dissimilar material layer, that is, a layer of spheres of 6.36 mm diameter made of alumina ceramics and steel, is placed in the particle packing. The effects of the dissimilar material layers were examined. The motion of the steel projectile and particle packing was recorded by a high-speed video camera. The experimental results obtained using force sensors at the base plate showed that the dissimilar material layers reduced the contact forces at the base plate.

  9. Suitability of polystyrene as a functional barrier layer in coloured food contact materials.

    Science.gov (United States)

    Genualdi, Susan; Addo Ntim, Susana; Begley, Timothy

    2015-01-01

    Functional barriers in food contact materials (FCMs) are used to prevent or reduce migration from inner layers in multilayer structures to food. The effectiveness of functional barrier layers was investigated in coloured polystyrene (PS) bowls due to their intended condition of use with hot liquids such as soups or stew. Migration experiments were performed over a 10-day period using USFDA-recommended food simulants (10% ethanol, 50% ethanol, corn oil and Miglyol) along with several other food oils. At the end of the 10 days, solvent dyes had migrated from the PS bowls at 12, 1 and 31,000 ng cm(-)(2) into coconut oil, palm kernel oil and Miglyol respectively, and in coconut oil and Miglyol the colour change was visible to the human eye. Scanning electron microscope (SEM) images revealed that the functional barrier was no longer intact for the bowls exposed to coconut oil, palm kernel oil, Miglyol, 10% ethanol, 50% ethanol and goat's milk. Additional tests showed that 1-dodecanol, a lauryl alcohol derived from palm kernel oil and coconut oil, was present in the PS bowls at an average concentration of 11 mg kg(-1). This compound is likely to have been used as a dispersing agent for the solvent dye and aided the migration of the solvent dye from the PS bowl into the food simulant. The solvent dye was not found in the 10% ethanol, 50% ethanol and goat's milk food simulants above their respective limits of detection, which is likely to be due to its insolubility in aqueous solutions. A disrupted barrier layer is of concern because if there are unregulated materials in the inner layers of the laminate, they may migrate to food, and therefore be considered unapproved food additives resulting in the food being deemed adulterated under the Federal Food Drug and Cosmetic Act. PMID:25569333

  10. Microscopic observation of pattern attack by aggressive ions on finished surface of aluminium alloy sacrificial anode

    International Nuclear Information System (INIS)

    This paper presents the results of a microscopic observation on submerged finished surface of aluminium alloy sacrificial anode. Experimental tests were carried out on polished surface aluminium anode exposed to seawater containing aggressive ions in order to observe of pattern corrosion attack on corroding surface of anode. Results have shown, at least under the present testing condition, that surface of sacrificial anode were attack by an aggressive ion such as chloride along grain boundaries. In addition, results of microanalysis showed that the corrosion products on surface of aluminium alloy have Al, Zn and O element for all sample and within the pit was consists of Al, Zn, O and Cl element. (author)

  11. Monolithic multilayer microfluidics via sacrificial molding of 3D-printed isomalt†

    OpenAIRE

    Gelber, Matthew K.; Bhargava, Rohit

    2015-01-01

    Here we demonstrate a method for creating multilayer or 3D microfluidics by casting a curable resin around a water-soluble, freestanding sacrificial mold. We use a purpose-built 3D printer to pattern self-supporting filaments of the sugar alcohol isomalt, which we then back-fill with a transparent epoxy resin. Dissolving the sacrificial mold leaves a network of cylindrical channels as well as input and output ports. We use this technique to fabricate a combinatorial mixer capable of producing...

  12. Visibility of atomically-thin layered materials buried in silicon dioxide

    Science.gov (United States)

    Simsek, Ergun; Mukherjee, Bablu

    2015-11-01

    Recently, the coating of thin oxide or nitride film on top of crystals of atomically-thin layered material (ATLM) has been introduced, which benefits optical and electrical properties of the materials and shields them from environmental contact, and has important implications for optoelectronics applications of layered materials. By calculating the reflection contrast, we show the possibility of using an additional oxide film on top of ATLM with good average optical color contrast in broad- and narrow-band wavelength ranges. Our work presents a more comprehensive map of optical color contrast of various ATLMs including graphene, MoS2, MoSe2, WS2, and WSe2 when kept in a sandwich structure between two thin SiO2 films on a Si substrate. The average color contrasts of ATLMs with varying thicknesses of SiO2 films at three different wavelength ranges (i.e. broadband range, range for green filtering and range for red filtering) have been discussed with a summary of optimized thicknesses of the top and bottom oxide films in order to achieve the highest color contrast from the sandwich structures.

  13. Atomic-scale friction modulated by potential corrugation in multi-layered graphene materials

    International Nuclear Information System (INIS)

    Friction is an important issue that has to be carefully treated for the fabrication of graphene-based nano-scale devices. So far, the friction mechanism of graphene materials on the atomic scale has not yet been clearly presented. Here, first-principles calculations were employed to unveil the friction behaviors and their atomic-scale mechanism. We found that potential corrugations on sliding surfaces dominate the friction force and the friction anisotropy of graphene materials. Higher friction forces correspond to larger corrugations of potential energy, which are tuned by the number of graphene layers. The friction anisotropy is determined by the regular distributions of potential energy. The sliding along a fold-line path (hollow-atop-hollow) has a relatively small potential energy barrier. Thus, the linear sliding observed in macroscopic friction experiments may probably be attributed to the fold-line sliding mode on the atomic scale. These findings can also be extended to other layer-structure materials, such as molybdenum disulfide (MoS2) and graphene-like BN sheets

  14. Finite Element Analysis of Layered Fiber Composite Structures Accounting for the Material's Microstructure and Delamination

    Science.gov (United States)

    Stier, Bertram; Simon, Jaan-Willem; Reese, Stefanie

    2015-04-01

    The present paper focuses on composite structures which consist of several layers of carbon fiber reinforced plastics (CFRP). For such layered composite structures, delamination constitutes one of the major failure modes. Predicting its initiation is essential for the design of these composites. Evaluating stress-strength relation based onset criteria requires an accurate representation of the through-the-thickness stress distribution, which can be particularly delicate in the case of shell-like structures. Thus, in this paper, a solid-shell finite element formulation is utilized which allows to incorporate a fully three-dimensional material model while still being suitable for applications involving thin structures. Moreover, locking phenomena are cured by using both the EAS and the ANS concept, and numerical efficiency is ensured through reduced integration. The proposed anisotropic material model accounts for the material's micro-structure by using the concept of structural tensors. It is validated by comparison to experimental data as well as by application to numerical examples.

  15. Colloidal-chemical properties of layer silicate dispersions used for production of highly porous glass-ceramic materials

    International Nuclear Information System (INIS)

    We study the processes of structure formation in dispersions of layered silicate montmorillonite for the production of highly porous materials with the addition of glass powder by duplication of a polyurethane matrix. Rheological properties of dispersions were regulated by polyvinyl alcohol. It is established that the dense layer of glass powder is formed after the application of glass containing a dispersion on the surface of a polymer template. The thickness of this layer depends on the PVA concentration in the system.

  16. Surface loading on and internal defects in layered magneto-electro-elastic materials and structures

    Science.gov (United States)

    Sangghaleh, Ali

    Magneto-electro-elastic (MEE) materials belong to the category of multi-phase materials where different phases within the materials including elastic, electric, and magnetic ones can interact for the optimal response. These materials are usually composites made of multi-phases or laminae and exhibit magnetoelectric (ME) coupling effect that is not present in the single-phase piezoelectric or piezomagnetic material. Piezoelectric materials display coupling effect between mechanical and electric fields and magnetostrictive materials display coupling effect between mechanical and magnetic fields. Material with an ME effect can exhibit an electric polarization under a magnetic field or a magnetization under an electric field. Natural ME effect is rare and the applications are limited due to the relatively small ME effect and response at low temperature. A few single-phase materials exhibit a weak ME effect. In contrast, a composite with piezoelectric and piezomagnetic phases can demonstrate a strong ME effect. The research on MEE materials started from 1970s and the development of MEEs picked up the pace since the production of high-quality single crystals as well as the improvement of techniques of thin film growth. Computational analyses have also helped to understand the coupling among elastic, electric, and magnetic orderings. In this study, new theoretical method is developed to understand the characteristics of anisotropic MEE materials under circular surface loadings. Numerical results demonstrate interesting features associated with different surface loads and could serve as benchmarks for future numerical methods where indentation research is involved. In addition, the analytical method is extended to analyze the fields produced by three-dimensional (3D) charged dislocations in MEE and piezoelectric (PE) bimaterials in which the materials are taken to be homogeneous and of general anisotropy. The solution is expressed in terms of simple line integrals along the dislocation loop with the integrand being the corresponding point-force Green's functions. The solution contains the piezoelectric, piezomagnetic, and purely elastic responses as special cases. The presented analytical solution and the obtained numerical results will provide a brilliant prospect to understand mechanical and physical behaviors of layered materials/structures and to improve the design and fabrication of novel semiconductors and photovoltaic devices.

  17. Optical properties of PbS-doped silica optical fiber materials based on atomic layer deposition

    International Nuclear Information System (INIS)

    Highlights: • PbS-doped silica optical fiber materials have been fabricated by ALD technique. • PbS-doped silica optical fiber materials are characterized through XPS, Raman and optical properties. • The local structure model of PbS-3MR for the PbS-doped optical fiber materials is built, and its optical properties are investigated using DFT. • The computed results of absorption and emission peaks are at 325.7 and 769.8 nm, which are good agreement with our experiment results. - Abstract: Optical properties of PbS-doped silica optical fiber materials and theoretical simulation are investigated. PbS is deposited on silica optical fiber materials by Atomic Layer Deposition (ALD) technique with Pb(tmhd)2 and H2S as Pb and S precursors, respectively. Its stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence states of S and Pb element are ?2 and +2, respectively. The Raman spectra further reveal that PbS has been doped into optical fiber materials almost without destroying irregular rings structure in silica material network. And there are distinct absorption bands at 248 and 352 nm. Fluorescence spectra are obtained with 330 and 350 nm pumping, two fluorescence peaks at 768 and 808 nm, respectively. In addition, the microstructure models for PbS-doped optical fiber materials are built on Gaussian09 platform, and its optical properties of the absorption and emission spectra are calculated using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. There are obvious absorption and emission peaks at 325.7 and 769.8 nm, respectively, which are in good agreement with experiments

  18. Crystal Chemical Concept of Arrangement and Function of Layered Superconducting Materials

    OpenAIRE

    Volkova, L. M.; Polyshchuk, S. A.; Magarill, S. A.; Herbeck, F. E.

    2002-01-01

    The crystal chemical concept of arrangement and function of layered superconducting materials is supposed. The concept is based on results of our investigation of crystal chemistry of high-temperature superconductors (HTSC) cuprates, diborides AB2 and borocarbides of nickel RNi2B2C. According to these results: (1) the main role in appearance of superconductivity played by the structural fragments - sandwiches A2(CuO2) in HTSC cuprates, A2(B2) in diborides and RB(Ni) in nicke...

  19. On the Analysis of Viscoelastic Materials for Active Constrained Layer Damping Treatments

    Science.gov (United States)

    Liao, W. H.; Wang, K. W.

    1997-10-01

    This paper is concerned with the investigations of viscoelastic material (VEM) effects on active constrained layer (ACL) based structures. Specific interests are on how the VEM parameters will influence the passive damping ability, the active action authority, and their combined effect in an ACL configuration. Using a beam example, the study has identified the VEM parameter regions that will provide the best active-passive hybrid actions. The results of this research can be used to develop guidelines to synthesize ACL structures that will outperform both the purely passive and active systems.

  20. Characteristics of Photonic Bandgap Fibres with Hollow Core's Inner Surface Coated by a Layer Material

    International Nuclear Information System (INIS)

    Hollow core's inner surface coating in a photonic bandgap fibre (PBGF) is investigated by means of finite element method. The coat material and thickness-dependence dispersion curve and group velocity dispersion are numerically studied. The coating with materials of low index or small thickness will rise up the dispersion curve but will not induce surface modes. However, coating with materials of high index or big coat thickness will induce surface modes and avoided-crossings. By varying coat material's refractive index and thickness, the appearances of surface modes and avoided-crossings can be changed. It is found that the avoided-crossing can enormously enlarge the negative dispersion which can find applications in dispersion compensation. We numerically achieve a negative dispersion as large as -21416.15 ps/nm/km. The results give a physical insight into the propagation properties of PBGFs with the hollow core coated by a layer of material and are of crucial significance in the applications of PBGF coating

  1. The effect of gamma-irradiation on few-layered graphene materials

    Energy Technology Data Exchange (ETDEWEB)

    Ansón-Casaos, A., E-mail: alanson@icb.csic.es [Instituto de Carboquímica, ICB-CSIC, Miguel Luesma Castán 4, 50018 Zaragoza (Spain); Puértolas, J.A. [Department of Materials Science and Technology-EINA, Instituto de Investigación en Ingeniería de Aragón, I3A, Universidad de Zaragoza, E-50018 Zaragoza (Spain); Pascual, F.J. [Department of Materials Science and Technology-EINA, Instituto de Investigación en Ingeniería de Aragón, I3A, Universidad de Zaragoza, E-50018 Zaragoza (Spain); Centro Universitario de la Defensa de Zaragoza, Academia General Militar, Carretera de Huesca s/n, E-50090 Zaragoza (Spain); Hernández-Ferrer, J. [Instituto de Carboquímica, ICB-CSIC, Miguel Luesma Castán 4, 50018 Zaragoza (Spain); Castell, P. [AITIIP Technological Center, Polígono Industrial Empresarium, C/Romero 12, 50720 Zaragoza (Spain); Benito, A.M.; Maser, W.K.; Martínez, M.T. [Instituto de Carboquímica, ICB-CSIC, Miguel Luesma Castán 4, 50018 Zaragoza (Spain)

    2014-05-01

    Highlights: • The effect of ?-irradiation was studied on two graphene materials. • Both graphene materials were examined in their oxidized and post-reduced forms. • We comparatively characterized ?-irradiation and chemical reduction effects. • Irradiation caused modifications in the graphene carbon lattice. • Small changes in the oxygen content occurred during irradiation. - Abstract: The effect of ?-irradiation on the structure and composition of chemically synthesized few-layered graphene materials was studied. Fully oxidized graphene oxide and graphene nanoribbons, as well as their respective chemically post-reduced forms, were treated under ?-irradiation in an air-sealed environment. Three different irradiation doses of 60, 90 and 150 kGy were applied. Structure and composition of the irradiated materials were analyzed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The XRD patterns were not affected by ?-irradiation, and small changes were observed in the FTIR and TGA results. However, significant modifications were detected by Raman spectroscopy and XPS, particularly in the Raman G/D band intensity ratios and in the C 1s XPS profiles. Comparatively, the changes in Raman and XPS spectra after ?-irradiation were even greater than those occurring during the chemical reduction of graphene oxides. Our results indicate that the graphene carbon lattice was strongly affected by ?-irradiation, but the materials experienced small variations in their oxygen content.

  2. Distinguishing crystallite size effects from those of structural disorder on the powder X-ray diffraction patterns of layered materials

    Indian Academy of Sciences (India)

    Sylvia Britto; Sumy Joseph; P Vishnu Kamath

    2010-09-01

    Both crystallite size effects and structural disorder contribute to the broadening of lines in the powder X-ray diffraction (PXRD) patterns of layered materials. Stacking faults, in particular, are ubiquitous in layered materials and aside from broadening also induce peaks due to select reflections to shift away from the Bragg positions. The effect of structural disorder has to be suitably discounted before the application of the Scherrer formula for the estimation of crystallite size.

  3. MODELLING OF ACOUSTIC EMISSION SIGNALS FOR THE CASE OF MATERIAL SURFACE LAYERS DISTRACTION IN THE PROCESS OF FRICTION

    Directory of Open Access Journals (Sweden)

    Sergey F. Filonenko

    2008-02-01

    Full Text Available  The obtained data of the resulting acoustic signals emission at the prevailing mechanism of the material surface layer wear under friction have been considered. It has been shown that the form and parameters of the acoustic emission resulting signals depend on the time of the initiation of type-I or type-II secondary structures fracture (rotation velocity of friction pair, as well as the stressed-deformed state of the materials’ surface layers of friction pairs.

  4. Cooperation of micro- and meso-porous carbon electrode materials in electric double-layer capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Cheng [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, Jilin Province (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Qi, Li; Wang, Hongyu [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, Jilin Province (China); Yoshio, Masaki [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan)

    2010-07-01

    The capacitive characteristics of micro- and meso-porous carbon materials have been compared in cyclic voltammetric studies and galvanostatic charge-discharge tests. Meso-porous carbon can keep certain high capacitance values at high scan rates, whereas micro-porous carbon possesses very high capacitance values at low scan rates but fades quickly as the scan rate rises up. For better performance of electric double-layer capacitors (EDLCs), the cooperative application of both kinds of carbon materials has been proposed in the following two ways: mixing both kinds of carbons in the same electrode or using the asymmetric configuration of carbon electrodes in the same EDLC. The cooperative effect on the electrochemical performance has also been addressed. (author)

  5. Holographic recording characteristics and applications of single-layer panchromatic dichromated gelatin material

    Science.gov (United States)

    Zhu, Jianhua; Xu, Min; Chen, Ligong; Guo, Yongkang; Guo, Lurong

    2005-09-01

    A high-quality single-layer panchromatic dichromated gelatin material is achieved successfully by employing new types of multi-color photosensitizers and photochemical promoters to conventional photo-crosslinking gelatin system. Its holographic recording characteristics such as spectral response, the photosensitivity of three primary colors, spectral selectivity of volume reflection hologram, angular and wavelength selectivity of volume transmission hologram, are studied in detail. Using red, green and blue lasers, namely three primary colors, the bright volume transmission and reflection holograms can be recorded on the panchromatic material at the exposure level of 30 mJ/cm2. Some preliminary results of space, angle and wavelength multiplexing holographic storage for storing multiple binary and grey-tone optical images, are also reported in this paper.

  6. Responses of benthic macroinvertebrates to thin-layer disposal of dredged material in Mississippi Sound, USA.

    Science.gov (United States)

    Wilber, Dara H; Clarke, Douglas G; Rees, Susan I

    2007-01-01

    Benthic community responses to thin-layer disposal of dredged material were assessed at three sites in Mississippi Sound, USA. Community composition differed between disposal and reference sites (ANOSIM) for each disposal event. Oweniid sand worms, Amphinomid fire worms, and brittle stars (Ophiuriodea) contributed the most to community distinctions between disposal and reference sites (SIMPER), with higher abundances at the disposal sites. Total infaunal abundance was similar to pre-disposal and reference conditions within 3-10 months of thin-layer disposal. Distinctions in community composition between disposal and reference sites (nMDS) persisted throughout the 16-month study period, but were less pronounced at the site where sediment composition was unchanged by disposal. Size distributions of some taxa (e.g., gastropod and hemichordate) suggest adults recolonized the newly deposited sediments either through vertical migration or lateral immigration from adjacent areas. Thin-layer disposal offers a viable alternative to conventional open-water disposal practices and warrants further exploration for other areas with deeper bathymetries and different hydrodynamic regimes. PMID:17052734

  7. Wannier function approach to realistic Coulomb interactions in layered materials and heterostructures

    Science.gov (United States)

    Rösner, M.; ?a??o?lu, E.; Friedrich, C.; Blügel, S.; Wehling, T. O.

    2015-08-01

    We introduce an approach to derive realistic Coulomb interaction terms in freestanding layered materials and vertical heterostructures from ab initio modeling of the corresponding bulk materials. To this end, we establish a combination of calculations within the framework of the constrained random-phase approximation, Wannier function representation of Coulomb matrix elements within some low-energy Hilbert space, and continuum medium electrostatics, which we call Wannier function continuum electrostatics (WFCE). For monolayer and bilayer graphene we reproduce full ab initio calculations of the Coulomb matrix elements within an accuracy of 0.3 eV or better. We show that realistic Coulomb interactions in bilayer graphene can be manipulated on the eV scale by different dielectric and metallic environments. A comparison to electronic phase diagrams derived in M. M. Scherer et al. [Phys. Rev. B 85, 235408 (2012), 10.1103/PhysRevB.85.235408] suggests that the electronic ground state of bilayer graphene is a layered antiferromagnet and remains surprisingly unaffected by these strong changes in the Coulomb interaction.

  8. Assessment of doses caused by electrons in thin layers of tissue-equivalent materials, using MCNP.

    Science.gov (United States)

    Heide, Bernd

    2013-10-01

    Absorbed doses caused by electron irradiation were calculated with Monte Carlo N-Particle transport code (MCNP) for thin layers of tissue-equivalent materials. The layers were so thin that the calculation of energy deposition was on the border of the scope of MCNP. Therefore, in this article application of three different methods of calculation of energy deposition is discussed. This was done by means of two scenarios: in the first one, electrons were emitted from the centre of a sphere of water and also recorded in that sphere; and in the second, an irradiation with the PTB Secondary Standard BSS2 was modelled, where electrons were emitted from an (90)Sr/(90)Y area source and recorded inside a cuboid phantom made of tissue-equivalent material. The speed and accuracy of the different methods were of interest. While a significant difference in accuracy was visible for one method in the first scenario, the difference in accuracy of the three methods was insignificant for the second one. Considerable differences in speed were found for both scenarios. In order to demonstrate the need for calculating the dose in thin small zones, a third scenario was constructed and simulated as well. The third scenario was nearly equal to the second one, but a pike of lead was assumed to be inside the phantom in addition. A dose enhancement (caused by the pike of lead) of ?113 % was recorded for a thin hollow cylinder at a depth of 0.007 cm, which the basal-skin layer is referred to in particular. Dose enhancements between 68 and 88 % were found for a slab with a radius of 0.09 cm for all depths. All dose enhancements were hardly noticeable for a slab with a cross-sectional area of 1 cm(2), which is usually applied to operational radiation protection. PMID:23576794

  9. Gigantic swelling of inorganic layered materials: a bridge to molecularly thin two-dimensional nanosheets.

    Science.gov (United States)

    Geng, Fengxia; Ma, Renzhi; Ebina, Yasuo; Yamauchi, Yusuke; Miyamoto, Nobuyoshi; Sasaki, Takayoshi

    2014-04-01

    Platy microcrystals of a typical layered material, protonated titanate, have been shown to undergo an enormous degree of swelling in aqueous solutions of various amines, including tertiary amines, quaternary ammonium hydroxides, and primary amines. Introducing these solutions expanded the crystal gallery height by up to ~100-fold. Through systematic analysis, we determined that ammonium ion intercalation is predominantly affected by the acid-base equilibrium and that the degree of swelling or inflow of H2O is controlled by the osmotic pressure balance between the gallery and the solution environment, both of which are relatively independent of electrolyte identity but substantially dependent on molarity. In solutions of tertiary amines and quaternary ammonium hydroxides, the uptake of ammonium ions increases nearly linearly with increasing external concentration before reaching a saturation plateau, i.e., ~40% relative to the cation-exchange capacity of the crystals used. The only exception is tetrabutylammonium ions, which yield a lower saturation value, ~30%, owing to steric effects. The swelling behaviors in some primary amine solutions differ as a result of the effect of attractive forces between amine solute molecules on the solution osmotic pressure. Although the swelling is essentially colligative in nature, the stability of the resultant swollen structure is heavily dependent on the chemical nature of the guest ions. Intercalated ions of higher polarity and smaller size help stabilize the swollen structure, whereas ions of lower polarity and larger size lead readily to exfoliation. The insight gained from this study sheds new light on both the incorporation of guest molecules into a gallery of layered structures in general and the exfoliation of materials into elementary single-layer nanosheets. PMID:24635385

  10. Simplified method of analysis of sacrificial shield wall for pipe whip restraint load

    International Nuclear Information System (INIS)

    the purpose of this paper is to analyze the sacrificial shield wall for the pipe whip load which is particularly important for the safety analysis and failure predictions of concrete reactor pressure vessel. The location of the shield wall makes it a very important structure for the support of the pipe whip restraints. The sacrificial shield wall is a composite structural steel and plain concrete, open-ended cylindrical shell structure stiffened by stiffening rings and vertical stiffeners. The restraint reaction loads act over a small area and are assumed to be concentrated and local loads on the sacrificial shield wall. The response of the sacrificial shield wall to the restraint-reaction load is assessed in terms of local effects and overall structural response which can be treated separately but are interrelated in actuality. Due to the complex physical processes involved with the analysis, local effects are evaluated primarily by the application of ring theory and the overall structural response by the beam theory. Local effects are evaluated considering a sector (-4500) of a ring of mean radius 'a' and subjected to a concentrated (two-pulse loading) dynamic load of magnitude 'F' at center (theta=00). Overall effects are evaluated by considering a cantilever cylindrical beam of mean radius 'a'. An effective spring and effective mass are used to represent the most contributing ring mode from the ring analysis described earlier into the beam model. The results of the simplified approach are compared with the results by the bending theory of

  11. New efficient preparation of arylzinc compounds from aryl halides using cobalt catalysis and sacrificial anode process

    Science.gov (United States)

    Gosmini; Rollin; Nedelec; Perichon

    2000-09-22

    Electroreduction of aryl-chlorides or -bromides in an electrochemical cell fitted with a sacrificial zinc anode and in the presence of cobalt halide associated with pyridine as ligand in DMF or acetonitrile as solvent affords the corresponding organozinc species in good yields. PMID:10987936

  12. The measurement of surface erosion of D9 material during laser ablation process by thin layer activation technique

    International Nuclear Information System (INIS)

    Thin layer activation (TLA) has been applied to study the surface erosion of D9 stainless steel material of fuel tube used in Indian nuclear power reactor, in micron order during laser ablation process. A beam of 15 MeV proton was chosen to produce a thin layer of activity in the surface (depth of activation ?428.6 ?m) of D9 material. The laser ablation of active sample was carried out with Nd-YAG laser (wavelength 1064 nm) with suitable parameters for satisfactory decontamination and also ablation. The surface loss of D9 material was less than 50 nm for the laser energy chosen for decontamination processes. (author)

  13. Role of the composition of lithium-rich layered oxide materials on the voltage decay

    Science.gov (United States)

    Peralta, David; Colin, Jean-François; Boulineau, Adrien; Simonin, Loïc; Fabre, Frédéric; Bouvet, Justin; Feydi, Pierre; Chakir, Mohamed; Chapuis, Marlène; Patoux, Sébastien

    2015-04-01

    Lithium-rich layered oxide is known to be one of the most promising positive electrode materials for high energy Li-ion batteries. Some publications report specific capacities higher than 250 mAh/g but the fade of the average potential during electrochemical cycling is an important drawback for commercial use of this material. The objective of this work is to study the origin of this potential decay during cycling of lithium-rich compounds. For this purpose, the electrochemical behavior of xLi2MnO3·(1-x)LiNi0.5Mn0.5O2 (with x = 1, 0.7, 0.5, 0.27) materials synthesized using coprecipitation route have been compared. For this study, complete or partial charge and discharge cycles have been performed in the 2.5 V-4.8 V voltage range. The results can be briefly summarized as follows: the potential decay is mainly provoked by several phenomena occurring at low potential, this growth being induced by the charging of lithium-rich at high voltage (>4.15 V). Whatever the compositions, same phenomena are involved, only the kinetics is modified.

  14. Enhanced photoconductivity in organic single-layered photoreceptors with bipolar charge transport materials

    International Nuclear Information System (INIS)

    The organic single-layered photoreceptors (SLPRs) consisting of polycarbonate (PC) matrix containing dispersed N,N'-diethyl-4-aminobenzaldehyde-1-phenyl-1'-(?-naphthyl)-hydrazone (BAH) and 2,4,7-trinitrylfluorenone (TNF) as bipolar charge (hole and electron) transport materials, as well as oxotitanium phthalocyanine (TiOPc) as charge generation materials (CGMs), were prepared. The influence of organic electron transport material (ETM) on the photosensitivity in the photoreceptors was investigated. It was found that small amount of TNF (TNF/BAH ?0.005) could improve the photosensitivity of photoreceptors greatly, i.e. the enhanced photoconductive effect, but the further increase of TNF concentration would lead to the decline of the photosensitivity. Differential scanning calorimeter (DSC), UV-Vis and cyclic voltammograms (CV) study showed that the enhanced photoconductivity might be resulted from the improvement of the separation efficiency of electron-hole pairs, and the decline of photosensitivity was due to the formation of the charge transfer complex (CTC) of TNF-BAH

  15. In Situ XRD Investigations on Structural Change of P2-Layered Materials during Electrochemical Sodiation/Desodiation

    DEFF Research Database (Denmark)

    Jung, Young Hwa; Johnsen, Rune E.

    2014-01-01

    Sodium layered oxides (NaxMO2) are attractive as positive electrode materials for rechargeable sodium-ion batteries (SIBs) due to high capacity, fast ionic diffusion and simple synthetic process. O3-layered lithium compounds have led successful commercialization of current lithium-ion batteries; as a result, rich experiences for structural studies of O3-layered compounds have been accumulated over the past decades. For sodium layered oxides, however, P2-layered compounds have been reported for better cyclability and structural stability during electrochemical reactions than O3-structure. Therefore, systematic studies on P2-layered materials for SIBs are highly required. In this study, we report the structural and electrochemical property of P2-NaxFeyMnyCo1-2yO2 synthesized by simple solid state reaction. The X-ray diffraction pattern of as-synthesized powder is indexed as a hexagonal lattice (P63/mmc, No.194), which is identical to P2-layered structure. The structural changes in hexagonal P2-layered oxides have been investigated during electrochemical sodiation/desodiation by in-situ synchrotron X-ray diffractions of a capillary based micro battery cell. From the result of in-situ studies, the initial layered structure is maintained from 2.0 to 4.0 V vs. Na+/Na during first desodiation. The phase transformation is observed over the 4.0 V, but the original P2 structure is completely restored at the following sodiation process. The relationship between structural and electrochemical properties of this P2-layered material will be discussed.

  16. Stacking sequence determines Raman intensities of observed interlayer shear modes in 2D layered materials - A general bond polarizability model

    Science.gov (United States)

    Luo, Xin; Lu, Xin; Cong, Chunxiao; Yu, Ting; Xiong, Qihua; Ying Quek, Su

    2015-10-01

    2D layered materials have recently attracted tremendous interest due to their fascinating properties and potential applications. The interlayer interactions are much weaker than the intralayer bonds, allowing the as-synthesized materials to exhibit different stacking sequences, leading to different physical properties. Here, we show that regardless of the space group of the 2D materials, the Raman frequencies of the interlayer shear modes observed under the typical configuration blue shift for AB stacked materials, and red shift for ABC stacked materials, as the number of layers increases. Our predictions are made using an intuitive bond polarizability model which shows that stacking sequence plays a key role in determining which interlayer shear modes lead to the largest change in polarizability (Raman intensity); the modes with the largest Raman intensity determining the frequency trends. We present direct evidence for these conclusions by studying the Raman modes in few layer graphene, MoS2, MoSe2, WSe2 and Bi2Se3, using both first principles calculations and Raman spectroscopy. This study sheds light on the influence of stacking sequence on the Raman intensities of intrinsic interlayer modes in 2D layered materials in general, and leads to a practical way of identifying the stacking sequence in these materials.

  17. Chemical resistance of thin film materials based on metal oxides grown by atomic layer deposition

    International Nuclear Information System (INIS)

    Etching rate of technologically important metal oxide thin films in hot sulphuric acid was investigated. The films of Al-, Ti-, Cr-, and Ta-oxides studied were grown by atomic layer deposition (ALD) method on silicon substrates from different precursors in large ranges of growth temperatures (80–900 °C) in order to reveal process parameters that allow deposition of coatings with higher chemical resistance. The results obtained demonstrate that application of processes that yield films with lower concentration of residual impurities as well as crystallization of films in thermal ALD processes leads to significant decrease of etching rate. Crystalline films of materials studied showed etching rates down to values of < 5 pm/s. - Highlights: • Etching of atomic layer deposited thin metal oxide films in hot H2SO4 was studied. • Smallest etching rates of < 5 pm/s for TiO2, Al2O3, and Cr2O3 were reached. • Highest etching rate of 2.8 nm/s for Al2O3 was occurred. • Remarkable differences in etching of non- and crystalline films were observed

  18. Non-destructive characterization of surface layers on non ferromagnetic materials

    International Nuclear Information System (INIS)

    Electromagnetic nondestructive techniques are usually applied to solve many inspection problems in industry. In particular, eddy currents are used for the detection of defects and the characterization of physical properties of metallic materials and components. One such application is the measurement of thickness of non conductive layers on a conducting substrate. A laboratory device for the quantitative determination of those thicknesses was developed at our laboratory. It works in the range from 0 to 100 ?m and was calibrated with a micro metre screw. This task involved the design and construction of the sensors their characterization (working frequency, resolution, sensitivity, etc.) and the setup of the mechanical system and the electronic signal generation and measurement circuit. (author)

  19. Local structure of layered oxide electrode materials for lithium-ion batteries.

    Science.gov (United States)

    Bareño, J; Lei, C H; Wen, J G; Kang, S-H; Petrov, I; Abraham, D P

    2010-03-12

    Li-ion batteries are promising candidates for electrical energy storage in applications ranging from portable electronics to hybrid and electric vehicles. In this context, layered compounds in the Li(1+delta)(TM(x)Mn(1-x))(1-delta)O(2) family (TM = transition metal) have received much attention due to their high capacity and stability. In this Research News article we describe recent advances on structural characterization of Li-ion electrode materials using state-of-the-art electron microscopy. Direct evidence of the monoclinic nature of Li(2)MnO(3) has been provided. It has been demonstrated that differences in Z-contrast imaging between Li(2)MnO(3) and LiTMO(2) may be used to screen samples for phase separation in the 10-100 nm scale. PMID:20401936

  20. Comparative Study of Charge Trapping Type SOI-FinFET Flash Memories with Different Blocking Layer Materials

    Directory of Open Access Journals (Sweden)

    Yongxun Liu

    2014-06-01

    Full Text Available The scaled charge trapping (CT type silicon on insulator (SOI FinFET flash memories with different blocking layer materials of Al2O3 and SiO2 have successfully been fabricated, and their electrical characteristics including short-channel effect (SCE immunity, threshold voltage (Vt variability, and the memory characteristics have been comparatively investigated. It was experimentally found that the better SCE immunity and a larger memory window are obtained by introducing a high-k Al2O3 blocking layer instead of a SiO2 blocking layer. It was also confirmed that the variability of Vt before and after one program/erase (P/E cycle is almost independent of the blocking layer materials.

  1. Understanding the key parameters for the rational design of layered oxide materials by composite sol-gel procedures

    OpenAIRE

    Ould-Chikh, Samy; Brodusch, Nicolas; Crozet, Nathalie; Hemati, Mehrdji; Rouleau, Loïc

    2013-01-01

    Previous works have well demonstrated that particle size of the filler used in layered oxide formulation is the first important parameter and must be decreased below 5 ?m (Agrafiotis, 1999-2000 [10]). But once the particle size is set what are the next formulation parameters to highlight as critical? How do we improve cohesion and adhesion of the coatings? To highlight the key parameters driving the quality of coating, a model layered oxide material was prepared inside a pan granulator. The m...

  2. Protective or damage promoting effect of calcium carbonate layers on the surface of cement based materials in aqueous environments

    International Nuclear Information System (INIS)

    Cement based materials permanently exposed to aggressive aqueous environments are subject to chemical changes affecting their durability. However, this holds also for tap water that is considered to be not aggressive to cementitious materials, although in that case a formation of covering layers of CaCO3 on the alkaline surfaces is commonly supposed to provide protection against reactive transport processes. Thus, investigations of the structural and chemical properties of the material/water interface were carried out in laboratory experiments and case studies to elucidate the consequences of surface reactions for the durability of cement based materials exposed to tap water. Focused Ion Beam investigations revealed that a protective effect of a CaCO3 covering layer depends on its structural properties, which are in turn affected by the hydro-chemical conditions during crystallization. Surface precipitation of CaCO3 can trigger further chemical degradation, if the required calcium is supplied by the pore solution of the material.

  3. Natural convection around a horizontal solid cylinder wrapped with a layer of fibrous or porous material

    International Nuclear Information System (INIS)

    Heat losses in duct flow and heat transfer enhancement are investigated through an analysis of natural convection about a horizontal cylinder with a porous or fibrous coating. The porous substrate may be used for two purposes. According to its properties, it may be employed as an insulating material or as a means to surface augmentation. An optimization study is then carried out in order to find the best conditions that allow good thermal insulation or heat transfer rate improvement. The flow motion and heat transfer coefficient are predicted for various conditions. The results show that an efficient insulation which means less than 10% in heat losses is obtained for a porous layer thickness of 0.8x tube diameter and a permeability corresponding to Da ? 10-7. Nevertheless, there is a Darcy number limit above which convection must be accounted for. Porous or fibrous materials may also be used as a heat transfer augmentation technique. To achieve this goal, porous media with high permeability and/or high effective thermal conductivity must be selected

  4. Sacrificial Tamper Slows Down Sample Explosion in FLASH Diffraction Experiments

    International Nuclear Information System (INIS)

    Intense and ultrashort x-ray pulses from free-electron lasers open up the possibility for near-atomic resolution imaging without the need for crystallization. Such experiments require high photon fluences and pulses shorter than the time to destroy the sample. We describe results with a new femtosecond pump-probe diffraction technique employing coherent 0.1 keV x rays from the FLASH soft x-ray free-electron laser. We show that the lifetime of a nanostructured sample can be extended to several picoseconds by a tamper layer to dampen and quench the sample explosion, making <1 nm resolution imaging feasible.

  5. Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses

    DEFF Research Database (Denmark)

    Stöhr, Frederik; Michael-Lindhard, Jonas; Hübner, Jörg; Jensen, Flemming; Simons, Hugh; Jakobsen, Anders Clemen; Poulsen, Henning Friis; Hansen, Ole

    2015-01-01

    This article describes the realization of complex high-aspect ratio silicon structures with feature dimensions from 100 lm to 100nm by deep reactive ion etching using the Bosch process. As the exact shape of the sidewall profiles can be crucial for the proper functioning of a device, the authors investigated how sacrificial structures in the form of guarding walls and pillars may be utilized to facilitate accurate control of the etch profile. Unlike other sacrificial structuring approaches, no s...

  6. Structural and Chemical Evolution of Li- and Mn-rich Layered Cathode Material

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jianming; Xu, Pinghong; Gu, Meng; Xiao, Jie; Browning, Nigel D.; Yan, Pengfei; Wang, Chong M.; Zhang, Jiguang

    2015-02-24

    Lithium (Li)- and manganese-rich (LMR) layered-structure materials are very promising cathodes for high energy density lithium-ion batteries. However, their voltage fading mechanism and its relationships with fundamental structural changes are far from being sufficiently understood. Here we report the detailed phase transformation pathway in the LMR cathode (Li[Li0.2Ni0.2Mn0.6]O2) during cycling for the samples prepared by hydro-thermal assistant method. It is found the transformation pathway of LMR cathode is closely correlated to its initial structure and preparation conditions. The results reveal that LMR cathode prepared by HA approach experiences a phase transformation from the layered structure to a LT-LiCoO2 type defect spinel-like structure (Fd-3m space group) and then to a disordered rock-salt structure (Fm-3m space group). The voltage fade can be well correlated with the Li ion insertion into octahedral sites, rather than tetrahedral sites, in both defect spinel-like structure and disordered rock-salt structure. The reversible Li insertion/removal into/from the disordered rock-salt structure is ascribed to the Li excess environment that can satisfy the Li percolating in the disordered rock-salt structure despite the increased kinetic barrier. Meanwhile, because of the presence of a great amount of oxygen vacancies, a significant decrease of Mn valence is detected in the cycled particle, which is below that anticipated for a potentially damaging Jahn-Teller distortion (+3.5). Clarification of the phase transformation pathway, cation redistribution, oxygen vacancy and Mn valence change undoubtedly provides insights into a profound understanding on the voltage fade, and capacity degradation of LMR cathode. The results also inspire us to further enhance the reversibility of LMR cathode via improving its surface structural stability.

  7. Processing of Nanosensors Using a Sacrificial Template Approach

    Science.gov (United States)

    Biaggi-Labiosa, Azlin M.; Hunter, Gary W.

    2012-01-01

    A new microsensor fabrication approach has been demonstrated based upon the use of nanostructures as templates. The fundamental idea is that existing nanostructures, such as carbon nano tubes or biological structures, have a material structure that can be used advantageously in order to provide new sensor systems but lack the advantages of some materials to, for example, operate at high temperatures. The approach is to start with a template using nanostructures such as a carbon nanotube. This template can then be coated by an oxide material with higher temperature capabilities. Upon heating in air, the carbon nanotube template is burned off, leaving only the metal oxide nanostructure. The resulting structure has a combination of the crystal structure and surface morphology of the carbon nanotube, combined with the material durability and hightemperature- sensing properties of the metal oxide. Further, since the metal oxide nanocrystals are deposited on the carbon nanotube, after burn-off what is left is a metal oxide porous nanostructure. This makes both the interior and the exterior of this nano structured sensor available for gas species detection. This, in effect, increases the surface area available for sensing, which has been shown in the past to significantly increase sensor performance.

  8. EFFECTIVE LAYERED MATERIALS WITH TRANZITION ZONE FROM NANOPARTICLES CREATED IN VOLUME OF COMPOSITE / ??????????? ???????? ????????? ? ?????????? ????? ?? ??????????, ????????????? ? ?????? ?????????

    Directory of Open Access Journals (Sweden)

    Sokov V. N. / ????? ?????? ??????????

    2014-10-01

    Full Text Available The authors describe the developed energy-effective and speedy technology of three-layered monolithic products with developed specific surface area and nanostructured transition zone between layers created by hydro thermal and power field / ??????? ????????????? ????????????????? ? ?????????? ?????????? ??????????? ?????????? ??????? ? ???????? ???????? ???????????? ? ????????????????????? ?????????? ????? ????? ??????, ??????????? ????????????????? ?????

  9. 'Utilitarian' judgments in sacrificial moral dilemmas do not reflect impartial concern for the greater good.

    Science.gov (United States)

    Kahane, Guy; Everett, Jim A C; Earp, Brian D; Farias, Miguel; Savulescu, Julian

    2015-01-01

    A growing body of research has focused on so-called 'utilitarian' judgments in moral dilemmas in which participants have to choose whether to sacrifice one person in order to save the lives of a greater number. However, the relation between such 'utilitarian' judgments and genuine utilitarian impartial concern for the greater good remains unclear. Across four studies, we investigated the relationship between 'utilitarian' judgment in such sacrificial dilemmas and a range of traits, attitudes, judgments and behaviors that either reflect or reject an impartial concern for the greater good of all. In Study 1, we found that rates of 'utilitarian' judgment were associated with a broadly immoral outlook concerning clear ethical transgressions in a business context, as well as with sub-clinical psychopathy. In Study 2, we found that 'utilitarian' judgment was associated with greater endorsement of rational egoism, less donation of money to a charity, and less identification with the whole of humanity, a core feature of classical utilitarianism. In Studies 3 and 4, we found no association between 'utilitarian' judgments in sacrificial dilemmas and characteristic utilitarian judgments relating to assistance to distant people in need, self-sacrifice and impartiality, even when the utilitarian justification for these judgments was made explicit and unequivocal. This lack of association remained even when we controlled for the antisocial element in 'utilitarian' judgment. Taken together, these results suggest that there is very little relation between sacrificial judgments in the hypothetical dilemmas that dominate current research, and a genuine utilitarian approach to ethics. PMID:25460392

  10. Biofabrication of multi-material anatomically shaped tissue constructs

    International Nuclear Information System (INIS)

    Additive manufacturing in the field of regenerative medicine aims to fabricate organized tissue-equivalents. However, the control over shape and composition of biofabricated constructs is still a challenge and needs to be improved. The current research aims to improve shape, by converging a number of biocompatible, quality construction materials into a single three-dimensional fiber deposition process. To demonstrate this, several models of complex anatomically shaped constructs were fabricated by combined deposition of poly(vinyl alcohol), poly(?-caprolactone), gelatin methacrylamide/gellan gum and alginate hydrogel. Sacrificial components were co-deposited as temporary support for overhang geometries and were removed after fabrication by immersion in aqueous solutions. Embedding of chondrocytes in the gelatin methacrylamide/gellan component demonstrated that the fabrication and the sacrificing procedure did not affect cell viability. Further, it was shown that anatomically shaped constructs can be successfully fabricated, yielding advanced porous thermoplastic polymer scaffolds, layered porous hydrogel constructs, as well as reinforced cell-laden hydrogel structures. In conclusion, anatomically shaped tissue constructs of clinically relevant sizes can be generated when employing multiple building and sacrificial materials in a single biofabrication session. The current techniques offer improved control over both internal and external construct architecture underscoring its potential to generate customized implants for human tissue regeneration. (paper)

  11. Tube Formation in Nanoscale Materials

    Directory of Open Access Journals (Sweden)

    Yan Chenglin

    2008-01-01

    Full Text Available Abstract The formation of tubular nanostructures normally requires layered, anisotropic, or pseudo-layered crystal structures, while inorganic compounds typically do not possess such structures, inorganic nanotubes thus have been a hot topic in the past decade. In this article, we review recent research activities on nanotubes fabrication and focus on three novel synthetic strategies for generating nanotubes from inorganic materials that do not have a layered structure. Specifically, thermal oxidation method based on gas–solid reaction to porous CuO nanotubes has been successfully established, semiconductor ZnS and Nb2O5nanotubes have been prepared by employing sacrificial template strategy based on liquid–solid reaction, and an in situ template method has been developed for the preparation of ZnO taper tubes through a chemical etching reaction. We have described the nanotube formation processes and illustrated the detailed key factors during their growth. The proposed mechanisms are presented for nanotube fabrication and the important pioneering studies are discussed on the rational design and fabrication of functional materials with tubular structures. It is the intention of this contribution to provide a brief account of these research activities.

  12. Elimination of initial stress-induced curvature in a micromachined bi-material composite-layered cantilever

    Science.gov (United States)

    Liu, Ruiwen; Jiao, Binbin; Kong, Yanmei; Li, Zhigang; Shang, Haiping; Lu, Dike; Gao, Chaoqun; Chen, Dapeng

    2013-09-01

    Micro-devices with a bi-material-cantilever (BMC) commonly suffer initial curvature due to the mismatch of residual stress. Traditional corrective methods to reduce the residual stress mismatch generally involve the development of different material deposition recipes. In this paper, a new method for reducing residual stress mismatch in a BMC is proposed based on various previously developed deposition recipes. An initial material film is deposited using two or more developed deposition recipes. This first film is designed to introduce a stepped stress gradient, which is then balanced by overlapping a second material film on the first and using appropriate deposition recipes to form a nearly stress-balanced structure. A theoretical model is proposed based on both the moment balance principle and total equal strain at the interface of two adjacent layers. Experimental results and analytical models suggest that the proposed method is effective in producing multi-layer micro cantilevers that display balanced residual stresses. The method provides a generic solution to the problem of mismatched initial stresses which universally exists in micro-electro-mechanical systems (MEMS) devices based on a BMC. Moreover, the method can be incorporated into a MEMS design automation package for efficient design of various multiple material layer devices from MEMS material library and developed deposition recipes.

  13. Development of a Biocompatible Layer-by-Layer Film System Using Aptamer Technology for Smart Material Applications

    OpenAIRE

    Amanda Foster; Maria C. DeRosa

    2014-01-01

    Aptamers are short, single-stranded nucleic acids that fold into well-defined three dimensional (3D) structures that allow for binding to a target molecule with affinities and specificities that can rival or in some cases exceed those of antibodies. The compatibility of aptamers with nanostructures such as thin films, in combination with their affinity, selectivity, and conformational changes upon target interaction, could set the foundation for the development of novel smart materials. In th...

  14. Multi-oxide active layer deposition using Applied Materials Pivot array coater for high-mobility metal oxide TFT

    Science.gov (United States)

    Park, Hyun Chan; Scheer, Evelyn; Witting, Karin; Hanika, Markus; Bender, Marcus; Hsu, Hao Chien; Yim, Dong Kil

    2015-09-01

    By controlling a thin indium tin oxide (ITO), indium zinc oxide interface layer between gate insulator and indium gallium zinc oxide (IGZO), the thin-film transistor (TFT) performance can reach higher mobility as conventional IGZO as well as superior stability. For large-area display application, Applied Materials static PVD array coater (Applied Materials GmbH & Co. KG, Alzenau, Germany) using rotary targets has been developed to enable uniform thin layer deposition in display industry. Unique magnet motion parameter optimization in Pivot sputtering coater is shown to provide very uniform thin ITO layer to reach TFT performance with high mobility, not only on small scale, but also on Gen8.5 (2500 × 2200 mm glass size) production system.

  15. Preparation and biological evaluation of a fibroblast growth factor-2-apatite composite layer on polymeric material

    International Nuclear Information System (INIS)

    A polymeric percutaneous device with good biocompatibility and resistance to bacterial infection is required clinically. In this study, a fibroblast growth factor-2 (FGF-2)-hydroxyapatite (HAp) composite layer (FHAp layer) was formed on the surfaces of ethylene-vinyl alcohol copolymer (EVOH) specimens using a coating process in a supersaturated calcium phosphate solution supplemented with FGF-2. FGF-2 in the FHAp layer retained its biological activity to promote proliferation of fibroblasts. The EVOH specimens coated with HAp and FHAp layers were percutaneously implanted in the scalp of rats. Not only the HAp layer but also the FHAp layer showed good biocompatibility, and FGF-2 showed no harmful effects on the skin tissue responses to the implanted specimen as long as 14 d. No significantly higher infection resistance was verified for the FHAp layer over the HAp layer, although an FHAp layer coated on a metallic percutaneous device for bone fixation demonstrated higher resistance to bacterial infection over an HAp layer in the previous study. The efficacy of FHAp layers coated on percutaneous implants in resistance to bacterial infection depends on physical factors including fixation condition, stiffness and movement of implants.

  16. Multiple pass and multiple layer friction stir welding and material enhancement processes

    Science.gov (United States)

    Feng, Zhili (Knoxville, TN) [Knoxville, TN; David, Stan A. (Knoxville, TN) [Knoxville, TN; Frederick, David Alan (Harriman, TN) [Harriman, TN

    2010-07-27

    Processes for friction stir welding, typically for comparatively thick plate materials using multiple passes and multiple layers of a friction stir welding tool. In some embodiments a first portion of a fabrication preform and a second portion of the fabrication preform are placed adjacent to each other to form a joint, and there may be a groove adjacent the joint. The joint is welded and then, where a groove exists, a filler may be disposed in the groove, and the seams between the filler and the first and second portions of the fabrication preform may be friction stir welded. In some embodiments two portions of a fabrication preform are abutted to form a joint, where the joint may, for example, be a lap joint, a bevel joint or a butt joint. In some embodiments a plurality of passes of a friction stir welding tool may be used, with some passes welding from one side of a fabrication preform and other passes welding from the other side of the fabrication preform.

  17. Refractory nanoporous materials fabricated using tungsten atomic layer deposition on silica aerogels

    International Nuclear Information System (INIS)

    We report an approach for preparing refractory nanoporous materials using high surface area silica aerogels as templates for the growth of conformal tungsten (W) coatings by atomic layer deposition (ALD). Nanoporous silica aerogel monoliths were prepared with a variety of initial pore sizes and initial densities in the range of 0.3-0.5 g/cc using porogen extraction methods. Next, W ALD using Si2H6 and WF6 reactants at 200 °C was employed to coat the inner surfaces of the silica aerogels. After coating, scanning electron microscopy revealed a microstructure in which the ALD W completely encapsulated the silica aerogel micro-cells. The porosity of the aerogels was preserved during the first 10 W ALD cycles allowing the density to be controlled by adjusting the number of W ALD cycles to achieve densities as high as 5 g/cc. Nitrogen adsorption surface area measurements revealed a gradual decrease in the surface area of the silica aerogels with increasing numbers of W ALD cycles, consistent with a partial filling of the aerogel voids. The high density nanoporous tungsten monoliths survived high temperature vacuum heating (1500 °C) making them promising candidates for solid rare-isotope catchers that can be used in the production of short-lived radioactive isotope beams in facilities such as the facility for rare isotope beams (FRIB).

  18. A sodium layered manganese oxides as 3 V cathode materials for secondary lithium batteries

    International Nuclear Information System (INIS)

    The synthesis of a new anhydrous sodium manganese oxide ?-Na0.66MnO2.13 obtained via a sol-gel process in organic medium is reported. The partial and limited removal of sodium ions from the layered host lattice (hexagonal symmetry; a = 2.84 A, c = 11.09 A) allows to get a high and stable specific capacity of 180 mAh g-1 at C/20 in the cycling limits 4.3/2 V with a mean working voltage of 3 V without the emergence of a spinel phase. By introducing acetylene black in solution during the sol-gel reaction, a composite material containing 8 wt.% AB has been obtained. The rate capability is shown to be significantly improved leading to an increase of the available specific capacity with for instance 200 and 90 mAh g-1 at C/20 and C rate. This effect is ascribed to a better electronic contact between particles and/or the modification of the oxide surface which makes the intercalation process more homogeneous and more efficient

  19. Low temperature silicon dioxide by thermal atomic layer deposition: Investigation of material properties

    Science.gov (United States)

    Hiller, D.; Zierold, R.; Bachmann, J.; Alexe, M.; Yang, Y.; Gerlach, J. W.; Stesmans, A.; Jivanescu, M.; Müller, U.; Vogt, J.; Hilmer, H.; Löper, P.; Künle, M.; Munnik, F.; Nielsch, K.; Zacharias, M.

    2010-03-01

    SiO2 is the most widely used dielectric material but its growth or deposition involves high thermal budgets or suffers from shadowing effects. The low-temperature method presented here (150 °C) for the preparation of SiO2 by thermal atomic layer deposition (ALD) provides perfect uniformity and surface coverage even into nanoscale pores, which may well suit recent demands in nanoelectronics and nanotechnology. The ALD reaction based on 3-aminopropyltriethoxysilane, water, and ozone provides outstanding SiO2 quality and is free of catalysts or corrosive by-products. A variety of optical, structural, and electrical properties are investigated by means of infrared spectroscopy, UV-Vis spectroscopy, secondary ion mass spectrometry, capacitance-voltage and current-voltage measurements, electron spin resonance, Rutherford backscattering, elastic recoil detection analysis, atomic force microscopy, and variable angle spectroscopic ellipsometry. Many features, such as the optical constants (n, k) and optical transmission and surface roughness (1.5 Å), are found to be similar to thermal oxide quality. Rapid thermal annealing (RTA) at 1000 °C is demonstrated to significantly improve certain properties, in particular by reducing the etch rate in hydrofluoric acid, oxide charges, and interface defects. Besides a small amount of OH groups and a few atomic per mille of nitrogen in the oxide remaining from the growth and curable by RTA no impurities could be traced. Altogether, the data point to a first reliable low temperature ALD-growth process for silicon dioxide.

  20. Determination of interfacial layers in high - k ALD nanolaminate materials by ARXPS and SRXPS measurements

    International Nuclear Information System (INIS)

    The interfacial layers of high dielectric constant (high-k) nanolaminate films are here explored. Problems concerning ALD nanolaminate layers deals mainly with lack of accurate methods to determine in depth profile of few nm thick stacks. Modified angle resolved XPS (ARXPS) and synchrotron radiation XPS(SRXPS) are proposed as methods suitable in layer profiling. Studied stacks containing ZrO/HfO or AlO/ZrO, were prepared on Si substrates by atomic layer deposition (ALD). Two sets of experiments were covered. First dealt with initial growth (up to 20 cycles, with thickness d<2 nm) of AlO/ZrO and included layer by layer insitu investigation by SRXPS. Second experiment refer to industrial grown ZrO/HfO films (d?3 nm) processed with various parameters resulting in both, layer by layer and homogenous depositions. For those samples ex situ XPS, with angle dependent variation of probing depth, measurements were covered. By comparing obtained intensity ratios for different angles with computational developed stack model it was found that no simple layer by layer but some intermixing growth occurred including interaction with silicon substrate.

  1. Determination of interfacial layers in high - k ALD nanolaminate materials by ARXPS and SRXPS measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Wyrodek, Jakub; Tallarida, Massimo; Schmeisser, Dieter [Brandenburgische Technische Universitaet, Angewandte Physik-Sensorik, Cottbus (Germany); Weisheit, Martin [GLOBALFOUNDRIES, Dresden (Germany)

    2010-07-01

    The interfacial layers of high dielectric constant (high-k) nanolaminate films are here explored. Problems concerning ALD nanolaminate layers deals mainly with lack of accurate methods to determine in depth profile of few nm thick stacks. Modified angle resolved XPS (ARXPS) and synchrotron radiation XPS(SRXPS) are proposed as methods suitable in layer profiling. Studied stacks containing ZrO/HfO or AlO/ZrO, were prepared on Si substrates by atomic layer deposition (ALD). Two sets of experiments were covered. First dealt with initial growth (up to 20 cycles, with thickness d<2 nm) of AlO/ZrO and included layer by layer insitu investigation by SRXPS. Second experiment refer to industrial grown ZrO/HfO films (d{proportional_to}3 nm) processed with various parameters resulting in both, layer by layer and homogenous depositions. For those samples ex situ XPS, with angle dependent variation of probing depth, measurements were covered. By comparing obtained intensity ratios for different angles with computational developed stack model it was found that no simple layer by layer but some intermixing growth occurred including interaction with silicon substrate.

  2. Numerical simulation of phase change material composite wallboard in a multi-layered building envelope

    International Nuclear Information System (INIS)

    Highlights: ? A numerical method to study the heat transfer through a PCM composite wallboard is presented. ? PCM wallboard can reduce energy consumption and shift peak electricity load. ? There is an optimal location for the PCM wallboard in the building envelop. ? The PCM wallboard performance depends on weather conditions. - Abstract: Phase change materials (PCMs) have the capability to store/release massive latent heat when undergoing phase change. When impregnated or encapsulated into wallboard or concrete systems, PCMs can greatly enhance their thermal energy storage capacity and effective thermal mass. When used in the building envelope PCM wallboard has the potential to improve building operation by reducing the energy requirement for maintaining thermal comfort, downsizing the AC/heating equipment, and shifting the peak load from the electrical grid. In this work we numerically studied the potential of PCM on energy saving for residential homes. For that purpose we solved the one-dimensional, transient heat equation through the multi-layered building envelope using the Crank–Nicolson discretization scheme. A source term is incorporated to account for the thermal-physical properties of the composite PCM wallboard. Using this code we examined a PCM composite wallboard incorporated into the walls and roof of a typical residential building across various climate zones. The PCM performance was studied under all seasonal conditions using the latest typical meteorological year (TMY3) data for exterior boundary conditions. Our simulations show that PCM performance highly depends on the weather conditions, emphasizing the necessity to choose different PCMs at different climate zones. Comparisons were also made between different PCM wallboard locations. Our work shows that there exists an optimal location for PCM placement within building envelope dependent upon the resistance values between the PCM layer and the exterior boundary conditions. We further identified the energy savings potential by comparing the performance of the PCM wallboard against the performance of a building envelope without PCM. Our study shows that PCM composite wallboard can reduce the energy consumption in summer and winter and can shift the peak electricity load in the summer

  3. Fabrication of functionally graded materials between P21 tool steel and Cu by using laser aided layered manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jong Seol; Shin, Ki Hoon [Seoul Nat' l Univ., Seoul (Korea, Republic of)

    2013-01-15

    With the development of layered manufacturing, thermally conductive molds or molds embedding conformal cooling channels can be directly fabricated. Although P21 tool steel is widely used as a mold material because of its dimensional stability, it is not efficient for cooling molds owing to its low thermal conductivity. Hence, the use of functionally graded materials (FGMs) between P21 and Cu may circumvent a tradeoff between the strength and the heat transfer rate. As a preliminary study for the layered manufacturing of thermally conductive molds having FGM structures, one dimensional P21 Cu FGMs were fabricated by using laser aided direct metal tooling (DMT), and then, material properties such as the thermal conductivity and specific heat that are related to the heat transfer were measured and analyzed.

  4. Cyclododecane as support material for clean and facile transfer of large-area few-layer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Capasso, A.; Leoni, E.; Dikonimos, T.; Buonocore, F.; Lisi, N. [ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre, Via Anguillarese 301, 00060 Rome (Italy); De Francesco, M. [ENEA, Technical Unit for Renewable Energies Sources, Casaccia Research Center, Via Anguillarese 301, 00060 Rome (Italy); Lancellotti, L.; Bobeico, E. [ENEA, Portici Research Centre, P.le E. Fermi 1, 80055 Portici (Italy); Sarto, M. S.; Tamburrano, A.; De Bellis, G. [Research Center on Nanotechnology Applied to Engineering of Sapienza (CNIS), SSNLab, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome (Italy)

    2014-09-15

    The transfer of chemical vapor deposited graphene is a crucial process, which can affect the quality of the transferred films and compromise their application in devices. Finding a robust and intrinsically clean material capable of easing the transfer of graphene without interfering with its properties remains a challenge. We here propose the use of an organic compound, cyclododecane, as a transfer material. This material can be easily spin coated on graphene and assist the transfer, leaving no residues and requiring no further removal processes. The effectiveness of this transfer method for few-layer graphene on a large area was evaluated and confirmed by microscopy, Raman spectroscopy, x-ray photoemission spectroscopy, and four-point probe measurements. Schottky-barrier solar cells with few-layer graphene were fabricated on silicon wafers by using the cyclododecane transfer method and outperformed reference cells made by standard methods.

  5. Tribological Investigations of Hard-Faced Layers and Base Materials of Forging Dies with Different Kinds of Lubricants Applied

    Directory of Open Access Journals (Sweden)

    V. Lazi?

    2010-12-01

    Full Text Available This paper gives a procedure for choosing the right technology for reparative hard facing of damaged forging dies. Since they are subject to impact loads and cyclic temperature elevations, forging dies should be made of steel that is able to withstand great impact loads, maintain good mechanical properties at elevated temperatures and that is resistant to wear and thermal fatigue. For these reasons, forging dies are made of conditionally weldable alloy tool steels; however it makes hard facing of damaged tools even more difficult. In this paper, wear resistance of base materials, hard-faced layers and heat-affected zones are tribologically investigated when two different lubricants - pure synthetical oil LM 76 and LM 76 with 6% molybdenum disulfide (MoS2 are applied. Tribological investigations have shown that the wear resistance of the hard faced layers is considerably greater than the wear resistance of the base material. However, the base material has better properties concerning friction.

  6. Thermal stability of gold nanoparticles embedded within metal oxide frameworks fabricated by hybrid modifications onto sacrificial textile templates.

    Science.gov (United States)

    Padbury, Richard P; Halbur, Jonathan C; Krommenhoek, Peter J; Tracy, Joseph B; Jur, Jesse S

    2015-01-27

    The stability and spatial separation of nanoparticles (NP's) is essential for employing their advantageous nanoscale properties. This work demonstrates the entrapment of gold NP's embedded in a porous inorganic matrix. Initially, gold NP's are decorated on fibrous nylon-6, which is used as an inexpensive sacrificial template. This is followed by inorganic modification using a novel single exposure cycle vapor phase technique resulting in distributed NP's embedded within a hybrid organic-inorganic matrix. The processing is extended to the synthesis of porous nanoflakes after calcination of the modified nylon-6 yielding a porous metal oxide framework surrounding the disconnected NP's with a surface area of 250 m(2)/g. A unique feature of this work is the use of a transmission electron microscope (TEM) equipped with an in situ annealing sample holder. The apparatus affords the opportunity to explore the underlying nanoscopic stability of NP's embedded in these frameworks in a single step. TEM analysis indicates thermal stability up to 670 °C and agglomeration characteristics thereafter. The vapor phase processes developed in this work will facilitate new complex NP/oxide materials useful for catalytic platforms. PMID:25557142

  7. Templating Sol-Gel Hematite Films with Sacrificial Copper Oxide: Enhancing Photoanode Performance with Nanostructure and Oxygen Vacancies.

    Science.gov (United States)

    Li, Yang; Guijarro, Néstor; Zhang, Xiaoli; Prévot, Mathieu S; Jeanbourquin, Xavier A; Sivula, Kevin; Chen, Hong; Li, Yongdan

    2015-08-12

    Nanostructuring hematite films is a critical step for enhancing photoelectrochemical performance by circumventing the intrinsic limitations on minority carrier transport. Herein, we present a novel sol-gel approach that affords nanostructured hematite films by including CuO as sacrificial templating agent. First, by annealing in air at 450 °C a film comprising an intimate mixture of CuO and Fe2O3 nanoparticles is obtained. The subsequent treatment with NaCl and annealing at 700 °C under Argon reveals a nanostructured highly crystalline hematite film devoid of copper. Photoelectrochemical investigations reveal that the incorporation of CuO as templating agent and the inert conditions employed during the annealing play a crucial role in the performance of the hematite electrodes. Mott-Schottky analysis shows a higher donor concentration when annealing in inert conditions, and even higher when combined with the NaCl treatment. These findings agree well with the presence of an oxygen-deficient shell on the material's surface evidenced by FT-IR and XPS measurements. Likewise, the incorporation of the CuO enhances the photocurrent obtained at 1.23 V from 0.55 to 0.8 mA·cm(-2) because of an improved nanostructure. Optimized films demonstrate an incident photon-to-current efficiency (IPCE) of 52% at 380 nm when applying 1.23 V versus RHE, and a faradaic efficiency for water splitting close to unity. PMID:26186065

  8. Layer by Layer Ex-Situ Deposited Cobalt-Manganese Oxide as Composite Electrode Material for Electrochemical Capacitor.

    Science.gov (United States)

    Rusi; Chan, P Y; Majid, S R

    2015-01-01

    The composite metal oxide electrode films were fabricated using ex situ electrodeposition method with further heating treatment at 300°C. The obtained composite metal oxide film had a spherical structure with mass loading from 0.13 to 0.21 mg cm(-2). The structure and elements of the composite was investigated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The electrochemical performance of different composite metal oxides was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD). As an active electrode material for a supercapacitor, the Co-Mn composite electrode exhibits a specific capacitance of 285 Fg(-1) at current density of 1.85 Ag(-1) in 0.5 M Na2SO4 electrolyte. The best composite electrode, Co-Mn electrode was then further studied in various electrolytes (i.e., 0.5 M KOH and 0.5 M KOH/0.04 M K3Fe(CN) 6 electrolytes). The pseudocapacitive nature of the material of Co-Mn lead to a high specific capacitance of 2.2 x 10(3) Fg(-1) and an energy density of 309 Whkg(-1) in a 0.5 M KOH/0.04 M K3Fe(CN) 6 electrolyte at a current density of 10 Ag(-1). The specific capacitance retention obtained 67% of its initial value after 750 cycles. The results indicate that the ex situ deposited composite metal oxide nanoparticles have promising potential in future practical applications. PMID:26158447

  9. Novel hetero-layered materials with tunable direct band gaps by sandwiching different metal disulfides and diselenides

    Science.gov (United States)

    Terrones, Humberto; López-Urías, Florentino; Terrones, Mauricio

    2013-01-01

    Although bulk hexagonal phases of layered semiconducting transition metal dichalcogenides (STMD) such as MoS2, WS2, WSe2 and MoSe2 exhibit indirect band gaps, a mono-layer of STMD possesses a direct band gap which could be used in the construction of novel optoelectronic devices, catalysts, sensors and valleytronic components. Unfortunately, the direct band gap only occurs for mono-layered STMD. We have found, using first principles calculations, that by alternating individual layers of different STMD (MoS2, WS2, WSe2 and MoSe2) with particular stackings, it is possible to generate direct band gap bi-layers ranging from 0.79 eV to 1.157?eV. Interestingly, in this direct band gap, electrons and holes are physically separated and localized in different layers. We foresee that the alternation of different STMD would result in the fabrication of materials with unprecedented optical and physico-chemical properties that would need further experimental and theoretical investigations. PMID:23528957

  10. Removal of a Degraded Concrete Layer with Emphasis on the Surface Optimization Before Application of Repair Material

    Directory of Open Access Journals (Sweden)

    Eva Janurova

    2012-01-01

    Full Text Available This contribution is concerned with the modelling of destructive effects of a high-velocity water jet, used as a tool for preparation of surfaces during reconstructions, on a degraded layer of concrete. The destruction action of a water jet on model material surfaces with artificially prepared degraded layers was studied both theoretically and experimentally. The tests were designed so their results could be consequently used for breaking of concrete during repairs of concrete constructions damaged by gaseous carbon and sulphur oxides, water during phase changes and chemical defrosting substances. The result is the determination of evaluation methodology of degraded and subsequently finished concrete surfaces.

  11. Spectroscopic investigations on thin adhesive layers in multi-material laminates.

    Science.gov (United States)

    Voronko, Yuliya; Chernev, Boril S; Eder, Gabriele C

    2014-01-01

    Three different spectroscopic approaches, Raman linescans, Raman imaging, and attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) imaging were evaluated for the visualization of the thin adhesive layers (3-6 ?m) present in polymeric photovoltaic backsheets. The cross-sections of the multilayer laminates in the original, weathered, and artificially aged samples were investigated spectroscopically in order to describe the impact of the environmental factors on the evenness and thickness of the adhesive layers. All three methods were found to be suitable tools to detect and visualize these thin layers within the original and aged polymeric laminates. However, as the adhesive layer is not very uniform in thickness and partly disintegrates upon weathering and/or artificial aging, Raman linescans yield only qualitative information and do not allow for an estimation of the layer thickness. Upon increasing the measuring area by moving from one-dimensional linescans to two-dimensional Raman images, a much better result could be achieved. Even though a longer measuring time has to be taken into account, the information on the uniformity and evenness of the adhesive layer obtainable using the imaging technique is much more comprehensive. Although Raman spectroscopy is known to have the superior lateral resolution as compared with ATR FT-IR spectroscopy, the adhesive layers of the samples used within this study (layer thickness 3-6 ?m) could also be detected and visualized by applying the ATR FT-IR spectroscopic imaging method. However, the analysis of the images was quite a demanding task, as the thickness of the adhesive layer was in the region of the resolution limit of this method. The information obtained for the impact of artificial aging and weathering on the adhesive layer obtained using Raman imaging and ATR FT-IR imaging was in good accordance. PMID:25014603

  12. Ciprofloxacin-intercalated Zinc Layered Hydroxides Hybrid Material: Synthesis and in Vitro Release Profiles of an Antibiotic Compound

    International Nuclear Information System (INIS)

    The intriguing anion exchange properties of layered hydroxides salts, combined with its high layer charge density have provided strong motivations for the potential use of the inorganic layered host material in drug delivery applications. Ciprofloxacin (CFX), a wide spectrum antibiotic has been anion exchanged with nitrate of zinc hydroxide nitrate (ZHN), which belongs to the LHS family, resulted in the expansion of the basal spacing from 9.92 Amstrom of ZHN to 21.5 Angstrom of ZCFX, the obtained hybrid material. Other characterizations, such as Fourier transform infra red spectroscopy (FTIR), CHNS analysis and TGA/ DTG have further corroborated this finding. Electron microscopy study reveals the plate-like structure of the nano hybrid material. The in vitro release of CFX was performed in phosphate saline buffer at pH 7.4 and it behaves in a slow and sustained release profile over a period of 72 hours. This study suggests that ZHN, which demonstrates a controlled release behavior, could be a potential host material in the drug delivery applications. (author)

  13. Encapsulation of sacrificial silicon containing particles for SH oxide ceramics via a boehmite precursor route:

    OpenAIRE

    Carabat, A.L.; Zwaag, S. van der; Sloof, W. G.

    2013-01-01

    Easy crack propagation in oxide ceramic coatings limits their application in high temperature environment (e.g. such as engines and gas turbine components) [1]. In order to overcome this problem, incorporation of sacrificial particles into an oxide ceramic coating may be a viable option. Particles of silicon compounds, such as: Si3N4, SiC, MoSi2, TaSi2 and WSi2 are attractive due to their unique features of producing a reaction product (i.e. SiO2) which fills the crack and bonds well to the s...

  14. Long-term performance of different aluminum alloy designs as sacrificial anodes for rebars

    International Nuclear Information System (INIS)

    This paper presents the performance of various cathodic-protection designs using Aluminum alloys to protect prestressed piles. The results obtained with different system designs (bracelete type-Al/Zn/In alloy, thermo sprayed aluminum (3-year evaluation) and conventional Al/Zn/In anodes in an epoxy-painted steel bracelet (12-year evaluation), indicated that all of these systems may be used as sacrificial anodes for pile protection. However, the thermo sprayed aluminum type can not be used in prestressed concrete piles because the very negative potentials (4) they supply to the reinforcement could lead to hydrogen embrittlement. (Author) 16 refs

  15. Efficiency of a Multi-Soil-Layering System on Wastewater Treatment Using Environment-Friendly Filter Materials

    Directory of Open Access Journals (Sweden)

    Chia-Chun Ho

    2015-03-01

    Full Text Available The multi-soil-layering (MSL system primarily comprises two parts, specifically, the soil mixture layer (SML and the permeable layer (PL. In Japan, zeolite is typically used as the permeable layer material. In the present study, zeolite was substituted with comparatively cheaper and more environmentally friendly materials, such as expanded clay aggregates, oyster shells, and already-used granular activated carbon collected from water purification plants. A series of indoor tests indicated that the suspended solid (SS removal efficiency of granular activated carbon was between 76.2% and 94.6%; zeolite and expanded clay aggregates achieved similar efficiencies that were between 53.7% and 87.4%, and oyster shells presented the lowest efficiency that was between 29.8% and 61.8%. Further results show that the oyster shell system required an increase of wastewater retention time by 2 to 4 times that of the zeolite system to maintain similar chemical oxygen demand (COD removal efficiency. Among the four MSL samples, the zeolite system and granular activated carbon system demonstrated a stable NH3-N removal performance at 92.3%–99.8%. The expanded clay aggregate system present lower removal performance because of its low adsorption capacity and excessively large pores, causing NO3?-N to be leached away under high hydraulic loading rate conditions. The total phosphorous (TP removal efficiency of the MSL systems demonstrated no direct correlation with the permeable layer material. Therefore, all MSL samples achieved a TP efficiency of between 92.1% and 99.2%.

  16. Efficiency of a multi-soil-layering system on wastewater treatment using environment-friendly filter materials.

    Science.gov (United States)

    Ho, Chia-Chun; Wang, Pei-Hao

    2015-03-01

    The multi-soil-layering (MSL) system primarily comprises two parts, specifically, the soil mixture layer (SML) and the permeable layer (PL). In Japan, zeolite is typically used as the permeable layer material. In the present study, zeolite was substituted with comparatively cheaper and more environmentally friendly materials, such as expanded clay aggregates, oyster shells, and already-used granular activated carbon collected from water purification plants. A series of indoor tests indicated that the suspended solid (SS) removal efficiency of granular activated carbon was between 76.2% and 94.6%; zeolite and expanded clay aggregates achieved similar efficiencies that were between 53.7% and 87.4%, and oyster shells presented the lowest efficiency that was between 29.8% and 61.8%. Further results show that the oyster shell system required an increase of wastewater retention time by 2 to 4 times that of the zeolite system to maintain similar chemical oxygen demand (COD) removal efficiency. Among the four MSL samples, the zeolite system and granular activated carbon system demonstrated a stable NH3-N removal performance at 92.3%-99.8%. The expanded clay aggregate system present lower removal performance because of its low adsorption capacity and excessively large pores, causing NO3--N to be leached away under high hydraulic loading rate conditions. The total phosphorous (TP) removal efficiency of the MSL systems demonstrated no direct correlation with the permeable layer material. Therefore, all MSL samples achieved a TP efficiency of between 92.1% and 99.2%. PMID:25809517

  17. Flaw investigation in a multi-layered, multi-material composite: Using air-coupled ultrasonic resonance imaging

    Science.gov (United States)

    Livings, R. A.; Dayal, V.; Barnard, D. J.; Hsu, D. K.

    2012-05-01

    Ceramic tiles are the main ingredient of a multi-material, multi-layered composite being considered for the modernization of tank armors. The high stiffness, low attenuation, and precise dimensions of these uniform tiles make them remarkable resonators when driven to vibrate. Defects in the tile, during manufacture or after usage, are expected to change the resonance frequencies and resonance images of the tile. The comparison of the resonance frequencies and resonance images of a pristine tile/lay-up to a defective tile/lay-up will thus be a quantitative damage metric. By examining the vibrational behavior of these tiles and the composite lay-up with Finite Element Modeling and analytical plate vibration equations, the development of a new Nondestructive Evaluation technique is possible. This study examines the development of the Air-Coupled Ultrasonic Resonance Imaging technique as applied to a hexagonal ceramic tile and a multi-material, multi-layered composite.

  18. Effect of Soft Material Hardness and Hard Material Surface Morphology on Friction and Transfer Layer Formation; Dry Condition

    Directory of Open Access Journals (Sweden)

    Mr.M Basavaraju

    2013-09-01

    Full Text Available The morphological features of the surface in both micro and macro levels are important factors governing the tribological behavior of the contacting surfaces. Surface hardness is also an important factor which governs the friction and wear behaviors of the contacting surfaces. Surface morphology of a tool is an important factor as it primarily controls the tribological behavior at the interface which in turn controls the surface finish of products. In the present investigation a pin-on-plate sliding tester was used to identify the effect of surface morphology and hardness on co-efficient of friction and transfer layer which characterizes the tribological behavior. The morphology of mild steel (EN8 plate surfaces were modified by employing three different surface modification methods like grinding (silicon carbide wheel polishing, shot blasting and electric discharge machining methods. Surface roughness parameters which characterize the morphology of the steel plates were measured using a three dimensional optical profilometer. Role of hardness is studied by employing lead, copper and Aluminum (Al6082 pins which were slid against steel plates. Experiments were conducted for plate inclination angles of 1, 1.5,2 and 2.5 degrees. Normal load was varied from 1 to 150N during the tests. Experiments were conducted under dry condition in ambient environment. Scanning electron microscope was used to study the formation of transfer layer on plate and pin surfaces. It was observed that the co-efficient of friction and transfer layer formation were found to depend on the surface morphology of the harder surface. The quantum of transfer layer formation on the surfaces is found to increase with increase in surface roughness

  19. Effect of Soft Material Hardness and Hard Material Surface Morphology on Friction and Transfer Layer Formation; Lubricated Condition

    Directory of Open Access Journals (Sweden)

    Dr.S Ranganatha

    2013-09-01

    Full Text Available Hot and cold forming of metals is carried out in industry for manufacturing engineering components. Such manufacturing processes employ dies, whose surface condition is one of the factors which characterize the surface finish of engineering components. The surface finish of engineering components is largely influenced by the tribological phenomenon at die and components interface. Lubrication, morphology and hardness of die surface are found to control surface finish of the products. In the present investigation a pin-on-plate sliding tester was used to identify the effect of surface morphology, lubrication and hardness on co-efficient of friction and transfer layer which characterizes the tribological behaviour. The morphology of mild steel (EN8 plate surfaces were modified by employing three different surface modification methods like grinding (silicon carbide wheel polishing, shot blasting and electric discharge machining methods. Surface roughness parameters which characterize the morphology of the steel plates were measured using a three dimensional optical profilometer. Role of hardness is studied by employing lead, copper and Aluminum (Al6082 pins which were slid against steel plates. Experiments were conducted for plate inclination angles of 1, 1.5,2 and 2.5 degrees. Normal load was varied from 1 to 150N during the tests. Experiments were conducted under lubricated condition in ambient environment. Scanning electron microscope was used to study the formation of transfer layer on plate and pin surfaces. It was observed that the co-efficient of friction and transfer layer formation were found to depend on the surface morphology of the harder surface under lubricated condition. The quantum of transfer layer formation on the surfaces is found to increase with increase in surface roughness.

  20. A WOOD REPLACEMENT MATERIAL OF SANDWICH STRUCTURE USING COIR FIBER MATS AND FIBERGLASS FABRICS AS CORE LAYER

    Directory of Open Access Journals (Sweden)

    Jia Yao,

    2011-12-01

    Full Text Available The tensile strength and bending strength of natural coir fiber are lower than many other natural fibers. Therefore, coir fiber is unsuitable for many fiber reinforcement applications. This study exploits the better shock resistance and toughness of coir fiber, which suggest that coir fiber can be used as a type of replacement material in plywood. Fast-growing poplar was chosen as the surface material, and coir fiber was selected as the core layer material for their buffering ability and toughness, and fiberglass fabrics were added in the core layer as strengthening components. The optimization of this plywood structure was carried out with an orthogonal experiment and the intuitive analysis method. The mechanical performance of some samples even exceeded that of natural wood. Through analysis of test results and scanning electron microscope (SEM observations, the buffering and toughening mechanisms of the coir fiber mats were revealed. This new material can be used to replace wood in plywood and in the transportation industry as a packaging material and as platform floors for freight vehicles.

  1. Melt-layer ejection and material changes of three different tungsten materials under high heat-flux conditions in the tokamak edge plasma of TEXTOR

    International Nuclear Information System (INIS)

    The behaviour of tungsten (W) plasma-facing components (PFCs) has been investigated in the plasma edge of the TEXTOR tokamak to study melt-layer ejection, macroscopic tungsten erosion from the melt layer as well as the changes of material properties such as grain-size and abundance of voids or bubbles. The parallel heat flux at the radial position of the exposed tungsten tile in the plasma ranges around q|| ? 45 MW m?2 causing samples to be exposed at an impact angle of 35° to 20–30 MW m?2. Locally the temperature reached up to 6000 K, high levels of evaporation and boiling are causing significant erosion in the form of continuous fine spray or droplet ejection. The amount of fine-spray tungsten emission depends strongly on the material properties: in the case of the tungsten–tantalum alloy the effect of spraying and droplet emission is significantly higher at even low temperatures when compared with regular tungsten or even ultra-high purity tungsten which shows almost no spraying at all. Differences in the material composition, grain structure and size may be related to the different evolution of macroscopic erosion. In addition the re-solidified material is studied and strong differences in terms of re-crystallized grain size and evolution of the grain structure and grain orientation are observed. The build up of large voids has been observed.

  2. Poromechanical modelling of hygric shrinkage and crystallization swelling in layered porous materials

    OpenAIRE

    Derluyn, Hannelore; Poupeleer, Anne-Séverine; Moonen, Peter; Carmeliet, Jan

    2007-01-01

    Salt ions may penetrate into building materials due to diffusive and convective transport processes through cracks or uncracked material parts. When drying occurs, the salts present in the material may crystallize first in coarse pores and subsequently in finer pores causing increasing expansive forces on the solid material. This process may finally lead to damage and cracking. Understanding the damage mechanism due to salt crystallization will contribute to a better knowledge on how to preve...

  3. Adhesive and stress-strain properties of the polymeric layered materials reinforced by the knitted net

    International Nuclear Information System (INIS)

    It is known that the textile materials (woven fabric and mesh) used for reinforcing of various polymer films and coatings. This paper discusses reinforcement of thermoplastic polymers based on PE (polyethylene) and PVC (polyvinyl Chloride) with a knitted mesh weave loin. According by the research identified adhesion, strength and deformation properties of new polymer laminates. The production of such materials has been discussed in detail and performance of resultant composites material is analyzed and compared with other materials. (author)

  4. Patterning Technology of Ferrite and Insulating Material in a Single Layer of the Multilayer Ceramic Device

    OpenAIRE

    Fumio Uchikoba; Ken Saito; Toshiki Fujino; Aki Kenmochi; Minami Takato

    2012-01-01

    Patterning technology of ferrite and insulating material in multilayer ceramic devices is proposed. In the conventional technology, the different ceramic materials such as the ferrite and the insulating material have been prepared in the form of the each different green sheet, and then they have been stacked each other. Otherwise the different material has filled cavities that were formed by a mechanical punching in advanced. In our proposing technology, arbitrary patterning of the different ...

  5. Molecular plating of thin lanthanide layers with improved material properties for nuclear applications

    International Nuclear Information System (INIS)

    This work describes experiments to gain an improved understanding of the processes associated with the electrochemical production of thin lanthanide layers for nuclear science investigations, i.e., nuclear targets. Nd, Sm, and Gd layers were prepared by means of the so-called molecular plating (MP) technique, where electrodeposition from an organic medium is usually performed in the constant current mode using two-electrode cells. The obtained results allowed the identification of optimized production conditions, which led to a significantly improved layer quality. Constant current density MP is a mass-transport controlled process. The applied current is maintained constant by constant fluxes of electroactive species towards the cathode - where the layer is grown - and the anode. The investigations showed the cell potentials of the electrodeposition systems to be always dominated by the ohmic drop produced by the resistance of the solutions used for the studies. This allowed to derive an expression relating cell potential with concentration of the electroactive species. This expression is able to explain the trends recorded with different electrolyte concentrations and it serves as a basis to get towards a full understanding of the reasons leading to the characteristic minima observed in the evolution of the cell potential curves with time. The minima were found to correspond to an almost complete depletion of the Nd ions obtained by dissolution of the model salt used for the investigations. Nd was confirmed to be deposited at the cathode as derivatives of Nd3+ - possibly as carboxylate, oxide or hydroxide. This fact was interpreted on the basis of the highly negative values of the standard redox potentials typical for lanthanide cations. Among the different electroactive species present in the complex MP solutions, the Nd3+ ions were found to contribute to less than 20% to the total current. Because of electrolysis, also the mixed solvent contributed to the applied constant current as an electroactive species. The presence of electrolyzed solvent was confirmed by the analysis of the produced deposits, which were always covered by both chemisorbed and physisorbed solvent molecules. Target characterizations showed the surfaces of the layers to present severe cracks, which were found to form during the drying time after completion of the MP. Different drying environments, i.e., air or Ar, did not affect the deposits. The drying-related nature of cracking and the solvent composition of the produced layers suggested to perform constant current density MPs using solvents with significantly different physical properties, most notably the boiling point. N,N-dimethylformamide (DMF), i.e., the highest boiling point solvent, proved to be very effective for the production of crack-free surfaces. DMF, in combination with the use of very smooth deposition substrates, allowed the growth of smooth, defectless layers, which likely underwent smaller stress during drying than the deposits produced by using rougher substrates and more volatile solvents. The roughness of the deposition substrate and the solvent used for the platings proved then to be core factors for the preparation of high quality layers. MP thus showed to be very effective for the production of uniform and homogeneous targets with excellent yield. Tests of the performance of layers produced by MP as ?-particle sources were also carried out. 147Sm was used as model isotope for the ? spectroscopy investigations. Both peak resolution and the fraction of ? particles reaching the detector were found to be influenced by source effects. These effects were categorized according to different ''layer variables'', i.e., variables influencing the ? spectra by means of ''layer effects'', and were found to be promoted by the plating solvent and the roughness of the deposition substrate used to perform the MPs. These parameters likely affected thickness, morphology, and growth mode of the layers. The layer variables proved to alter the relative detection efficiencies of the ? measu

  6. Molecular plating of thin lanthanide layers with improved material properties for nuclear applications

    Energy Technology Data Exchange (ETDEWEB)

    Vascon, Alessio

    2013-06-26

    This work describes experiments to gain an improved understanding of the processes associated with the electrochemical production of thin lanthanide layers for nuclear science investigations, i.e., nuclear targets. Nd, Sm, and Gd layers were prepared by means of the so-called molecular plating (MP) technique, where electrodeposition from an organic medium is usually performed in the constant current mode using two-electrode cells. The obtained results allowed the identification of optimized production conditions, which led to a significantly improved layer quality. Constant current density MP is a mass-transport controlled process. The applied current is maintained constant by constant fluxes of electroactive species towards the cathode - where the layer is grown - and the anode. The investigations showed the cell potentials of the electrodeposition systems to be always dominated by the ohmic drop produced by the resistance of the solutions used for the studies. This allowed to derive an expression relating cell potential with concentration of the electroactive species. This expression is able to explain the trends recorded with different electrolyte concentrations and it serves as a basis to get towards a full understanding of the reasons leading to the characteristic minima observed in the evolution of the cell potential curves with time. The minima were found to correspond to an almost complete depletion of the Nd ions obtained by dissolution of the model salt used for the investigations. Nd was confirmed to be deposited at the cathode as derivatives of Nd{sup 3+} - possibly as carboxylate, oxide or hydroxide. This fact was interpreted on the basis of the highly negative values of the standard redox potentials typical for lanthanide cations. Among the different electroactive species present in the complex MP solutions, the Nd{sup 3+} ions were found to contribute to less than 20% to the total current. Because of electrolysis, also the mixed solvent contributed to the applied constant current as an electroactive species. The presence of electrolyzed solvent was confirmed by the analysis of the produced deposits, which were always covered by both chemisorbed and physisorbed solvent molecules. Target characterizations showed the surfaces of the layers to present severe cracks, which were found to form during the drying time after completion of the MP. Different drying environments, i.e., air or Ar, did not affect the deposits. The drying-related nature of cracking and the solvent composition of the produced layers suggested to perform constant current density MPs using solvents with significantly different physical properties, most notably the boiling point. N,N-dimethylformamide (DMF), i.e., the highest boiling point solvent, proved to be very effective for the production of crack-free surfaces. DMF, in combination with the use of very smooth deposition substrates, allowed the growth of smooth, defectless layers, which likely underwent smaller stress during drying than the deposits produced by using rougher substrates and more volatile solvents. The roughness of the deposition substrate and the solvent used for the platings proved then to be core factors for the preparation of high quality layers. MP thus showed to be very effective for the production of uniform and homogeneous targets with excellent yield. Tests of the performance of layers produced by MP as ?-particle sources were also carried out. {sup 147}Sm was used as model isotope for the ? spectroscopy investigations. Both peak resolution and the fraction of ? particles reaching the detector were found to be influenced by source effects. These effects were categorized according to different ''layer variables'', i.e., variables influencing the ? spectra by means of ''layer effects'', and were found to be promoted by the plating solvent and the roughness of the deposition substrate used to perform the MPs. These parameters likely affected thickness, morphology, and growth mode of the layers. The layer variables proved to

  7. From a Philosophical point of view, can the Budism Be An Anti-Sacrificial Science?

    Directory of Open Access Journals (Sweden)

    Francisco Felizol Marques

    2014-04-01

    Full Text Available Both on Buddhist tradition and René Girard´s thought ignorance and desire are on the basis of suffering and violence. The Buddhist tradition puts/takes ignorance, that nothing exists in and by itself, avydia as the cause of all sufferings because it generates a chain of desire / aversion that leads us to an imprisonment where we move from desiring an object to another. Girard´s perspective founds violence´s origin on the ignorance of our mimetic desire. The subject ignores that, far from being free, autonomous and differentiated, as the "romantic lie" prays, he only desires and wants by imitating a model. Neither the subject nor the object, which the subject freely thinks to desire, exist free for themselves. While this model prevails, he will react more and more violently to the claims of the subject; and even if the subject overtakes its model, he will greedily seek another and another model, always doomed to deception. If we add to this the proximity of the two anti-sacrificial perspectives, displayed on the descriptive closeness of the samsara´s wheel and the circular and sacrificial time of a pagan society, we find between Girard and the buddhist tradition enough common points for their mutual understanding.

  8. Antibacterial activity of microstructured Ag/Au sacrificial anode thin films.

    Science.gov (United States)

    Köller, Manfred; Sengstock, Christina; Motemani, Yahya; Khare, Chinmay; Buenconsejo, Pio J S; Geukes, Jonathan; Schildhauer, Thomas A; Ludwig, Alfred

    2015-01-01

    Ten different Ag dot arrays (16 to 625 microstructured dots per square mm) were fabricated on a continuous Au thin film and for comparison also on Ti film by sputter deposition and photolithographic patterning. To analyze the antibacterial activity of these microstructured films Escherichia coli and Staphylococcus aureus were placed onto the array surfaces and cultivated overnight. To analyze the viability of planktonic as well as surface adherent bacteria, the applied bacterial fluid was subsequently aspirated, plated on blood agar plates and adherent bacteria were detected by fluorescence microscopy. A particular antibacterial effect towards both bacterial strains was induced by Ag dot arrays on fabricated Au thin film (sacrificial anode system for Ag), due to the release of Ag ions from dissolution of Ag dots in contrast to Ag dot arrays fabricated on the Ti thin films (non-sacrificial anode system for Ag) which remained intact to the original dot shape. The required number of Ag dots on gold film to achieve complete bactericidal effects for both bacterial strains was seven times lower than that observed with Ag dot arrays on Ti film. PMID:25491988

  9. Fabrication of scalable and structured tissue engineering scaffolds using water dissolvable sacrificial 3D printed moulds

    DEFF Research Database (Denmark)

    Mohanty, Soumyaranjan; Larsen, Layla Bashir

    2015-01-01

    One of the major challenges in producing large scale engineered tissue is the lack of ability to create large highly perfused scaffolds in which cells can grow at a high cell density and viability. Here, we explore 3D printed polyvinyl alcohol (PVA) as a sacrificial mould in a polymer casting process. The PVA mould network defines the channels and is dissolved after curing the polymer casted around it. The printing parameters determined the PVA filament density in the sacrificial structure and this density resulted in different stiffness of the corresponding elastomer replica. It was possible to achieve 80% porosity corresponding to about 150 cm2/cm3 surface to volume ratio. The process is easily scalable as demonstrated by fabricating a 75 cm3 scaffold with about 16,000 interconnected channels (about 1 m2 surface area) and with a channel to channel distance of only 78 ?m. To our knowledge this is the largest scaffold ever to be produced with such small feature sizes and with so many structuredchannels. The fabricated scaffoldswere applied for in-vitro culturing of hepatocytes over a 12-day culture period. Smaller scaffolds (6× 4mm) were tested for cell culturing and could support homogeneous cell growth throughoutthe scaffold. Presumably, the diffusion of oxygen and nutrient throughout the channel network is rapid enough to support cell growth. In conclusion, the described process is scalable, compatible with cell culture, rapid, and inexpensive.

  10. Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Michael D. Blanton

    2012-09-01

    Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

  11. Monitoring the Startup of a Sacrificial Concrete Sewer for Odor Control

    DEFF Research Database (Denmark)

    Nielsen, AsbjØrn Haaning; Vollertsen, Jes

    2014-01-01

    The use of a sacrificial concrete sewer for controlling sulphide-related odour downstream of a pressure sewer was investigated in this study. The investigated sewer is located in a rural catchment and is intended to alleviate odour problems downstream of a small diameter pressure sewer with extended retention time. For the purpose of the study, a 50-m long sacrificial concrete gravity sewer was constructed using a high alkalinity concrete pipe. The monitoring campaign reported in this paper covers the first 9 months of operation. The results clearly demonstrate the ability of the system to reduce hydrogen sulphide gas (H2S (g)) concentrations in the sewer headspace. After being in operation for approximately half a year, the system was able to maintain average H2S (g) levels of less than 1 ppmv at the downstream end, which is the first place air can escape. The daily maximum H2S (g) levels (95 percentile) were reduced from several hundred ppmv in the discharge manhole to approximately 10 ppmv at the downstream end. Thus, the odour potential has been significantly reduced. A visual inspection of the system revealed that even after 9 months of operation not all of the concrete surfaces were corroding. The removal efficiency is therefore expected to increase further.

  12. Fabrication of scalable and structured tissue engineering scaffolds using water dissolvable sacrificial 3D printed moulds.

    Science.gov (United States)

    Mohanty, Soumyaranjan; Larsen, Layla Bashir; Trifol, Jon; Szabo, Peter; Burri, Harsha Vardhan Reddy; Canali, Chiara; Dufva, Marin; Emnéus, Jenny; Wolff, Anders

    2015-10-01

    One of the major challenges in producing large scale engineered tissue is the lack of ability to create large highly perfused scaffolds in which cells can grow at a high cell density and viability. Here, we explore 3D printed polyvinyl alcohol (PVA) as a sacrificial mould in a polymer casting process. The PVA mould network defines the channels and is dissolved after curing the polymer casted around it. The printing parameters determined the PVA filament density in the sacrificial structure and this density resulted in different stiffness of the corresponding elastomer replica. It was possible to achieve 80% porosity corresponding to about 150 cm(2)/cm(3) surface to volume ratio. The process is easily scalable as demonstrated by fabricating a 75 cm(3) scaffold with about 16,000 interconnected channels (about 1m(2) surface area) and with a channel to channel distance of only 78 ?m. To our knowledge this is the largest scaffold ever to be produced with such small feature sizes and with so many structured channels. The fabricated scaffolds were applied for in-vitro culturing of hepatocytes over a 12-day culture period. Smaller scaffolds (6×4 mm) were tested for cell culturing and could support homogeneous cell growth throughout the scaffold. Presumably, the diffusion of oxygen and nutrient throughout the channel network is rapid enough to support cell growth. In conclusion, the described process is scalable, compatible with cell culture, rapid, and inexpensive. PMID:26117791

  13. Ab initio and thermodynamic modelling of alloying effects on activity of sacrificial aluminium anodes

    International Nuclear Information System (INIS)

    Research highlights: ? Effect of alloying on the corrosion activity of sacrificial Al anodes. ? Sn in solid solution form is a key alloying element for activation of Al anodes. ? Ternary additions that increase Sn solubility decrease the potential of Al alloys. ? Elements bigger than Al expand the Al lattice and allow more Sn to dissolve in Al. ? Large ternary dopants can reduce Sn's solubility in Al if they form compounds with Sn. - Abstract: This work summarizes the experimental literature to date on Al-alloy sacrificial anodes and shows that the presence of Sn as an alloying element in solid solution form consistently debases the alloy corrosion potential. This study then assesses the lattice expander theory, which states that lattice-expanding dopants can be used to increase Sn solubility in Al and thereby reduce passivation. The thermodynamic effects on Sn solubility of lattice expanders (Ga, Mg, Zr, In and Bi) are predicted with ab-initio methods. Our results support lattice expander theory although we demonstrate that Sn solubility can decrease by alloying with even large dopants if they form compounds with Sn.

  14. [Ru(bpy)3]2+-doped silica nanoparticles within layer-by-layer biomolecular coatings and their application as a biocompatible electrochemiluminescent tag material.

    Science.gov (United States)

    Wei, Hui; Liu, Jifeng; Zhou, Lingling; Li, Jing; Jiang, Xiue; Kang, Jianzhen; Yang, Xiurong; Dong, Shaojun; Wang, Erkang

    2008-01-01

    [Ru(bpy)3]2+-doped silica (RuSi) nanoparticles were synthesized by using a water/oil microemulsion method. Stable electrochemiluminescence (ECL) was obtained when the RuSi nanoparticles were immobilized on a glassy carbon electrode by using tripropylamine (TPA) as a coreactant. Furthermore, the ECL of the RuSi nanoparticles with layer-by-layer biomolecular coatings was investigated. Squential self-assembly of the polyelectrolytes and biomolecules on the RuSi nanoparticles gave nanocomposite suspensions, the ECL of which decreased on increasing the number of bilayers. Moreover, factors that affected the assembly and ECL signals were investigated. The decrease in ECL could be assigned to steric hindrance and limited diffusion of the coreactant molecules in the silica matrix after they were attached to the biomolecules. Since surface modification of the RuSi nanoparticles can improve their biocompatibility and prevent leaking of the [Ru(bpy)3]2+ ions, the RuSi nanoparticles can be readily used as efficient and stable ECL tag materials in immunoassay and DNA detection. PMID:18306266

  15. N-trimethylchitosan/alginate layer-by-layer self assembly coatings act as "fungal repellents" to prevent biofilm formation on healthcare materials.

    Science.gov (United States)

    Jiang, Fuguang; Yeh, Chih-Ko; Wen, Jianchuan; Sun, Yuyu

    2015-02-18

    Fungal biofilm formation on healthcare materials is a significant clinical concern, often leading to medical-device-related infections, which are difficult to treat. A novel fungal repellent strategy is developed to control fungal biofilm formation. Methylacrylic acid (MAA) is grated onto poly methyl methacrylate (PMMA)-based biomaterials via plasma-initiated grafting polymerization. A cationic polymer, trimethylchitosan (TMC), is synthesized by reacting chitosan with methyl iodide. Sodium alginate (SA) is used as an anionic polymer. TMC/SA multilayers are coated onto the MAA-grafted PMMA via layer-by-layer self-assembly. The TMC/SA multilayer coatings significantly reduce fungal initial adhesion, and effectively prevent fungal biofilm formation. It is concluded that the anti-adhesive property of the surface is due to its hydrophilicity, and that the biofilm-inhibiting action is attributed to the antifungal activity of TMC as well as the chelating function of TMC and SA, which may have acted as fungal repellents. Phosphate buffered saline (PBS)-immersion tests show that the biofilm-modulating effect of the multilayer coatings is stable for more than 4 weeks. Furthermore, the presence of TMC/SA multilayer coatings improves the biocompatibility of the original PMMA, offering a simple, yet effective, strategy for controlling fungal biofilm formation. PMID:25295485

  16. Role of atomic layer deposited aluminum oxide as oxidation barrier for silicon based materials

    Energy Technology Data Exchange (ETDEWEB)

    Fiorentino, Giuseppe, E-mail: g.fiorentino@tudelft.nl; Morana, Bruno [Department of Microelectronic, Delft University of Technology, Feldmannweg 17, 2628 CT Delft (Netherlands); Forte, Salvatore [Department of Electronic, University of Naples Federico II, Piazzale Tecchio, 80125 Napoli (Italy); Sarro, Pasqualina Maria [Department of Microelectronic, Delft University of Technology, Feldmannweg 17, 2628 CT, Delft (Netherlands)

    2015-01-15

    In this paper, the authors study the protective effect against oxidation of a thin layer of atomic layer deposited (ALD) aluminum oxide (Al{sub 2}O{sub 3}). Nitrogen doped silicon carbide (poly-SiC:N) based microheaters coated with ALD Al{sub 2}O{sub 3} are used as test structure to investigate the barrier effect of the alumina layers to oxygen and water vapor at very high temperature (up to 1000?°C). Different device sets have been fabricated changing the doping levels, to evaluate possible interaction between the dopants and the alumina layer. The as-deposited alumina layer morphology has been evaluated by means of AFM analysis and compared to an annealed sample (8 h at 1000?°C) to estimate the change in the grain structure and the film density. The coated microheaters are subjected to very long oxidation time in dry and wet environment (up to 8 h at 900 and 1000?°C). By evaluating the electrical resistance variation between uncoated reference devices and the ALD coated devices, the oxide growth on the SiC is estimated. The results show that the ALD alumina coating completely prevents the oxidation of the SiC up to 900?°C in wet environment, while an oxide thickness reduction of 50% is observed at 1000?°C compared to uncoated devices.

  17. Role of atomic layer deposited aluminum oxide as oxidation barrier for silicon based materials

    International Nuclear Information System (INIS)

    In this paper, the authors study the protective effect against oxidation of a thin layer of atomic layer deposited (ALD) aluminum oxide (Al2O3). Nitrogen doped silicon carbide (poly-SiC:N) based microheaters coated with ALD Al2O3 are used as test structure to investigate the barrier effect of the alumina layers to oxygen and water vapor at very high temperature (up to 1000?°C). Different device sets have been fabricated changing the doping levels, to evaluate possible interaction between the dopants and the alumina layer. The as-deposited alumina layer morphology has been evaluated by means of AFM analysis and compared to an annealed sample (8 h at 1000?°C) to estimate the change in the grain structure and the film density. The coated microheaters are subjected to very long oxidation time in dry and wet environment (up to 8 h at 900 and 1000?°C). By evaluating the electrical resistance variation between uncoated reference devices and the ALD coated devices, the oxide growth on the SiC is estimated. The results show that the ALD alumina coating completely prevents the oxidation of the SiC up to 900?°C in wet environment, while an oxide thickness reduction of 50% is observed at 1000?°C compared to uncoated devices

  18. Heat transfer and material flow during laser assisted multi-layer additive manufacturing

    International Nuclear Information System (INIS)

    A three-dimensional, transient, heat transfer, and fluid flow model is developed for the laser assisted multilayer additive manufacturing process with coaxially fed austenitic stainless steel powder. Heat transfer between the laser beam and the powder particles is considered both during their flight between the nozzle and the growth surface and after they deposit on the surface. The geometry of the build layer obtained from independent experiments is compared with that obtained from the model. The spatial variation of melt geometry, cooling rate, and peak temperatures is examined in various layers. The computed cooling rates and solidification parameters are used to estimate the cell spacings and hardness in various layers of the structure. Good agreement is achieved between the computed geometry, cell spacings, and hardness with the corresponding independent experimental results.

  19. Fundamental degradation mechanisms of layered oxide Li-ion battery cathode materials: Methodology, insights and novel approaches

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Description of recent in operando and in situ analysis methodology. • Surface science approach using photoemission for analysis of cathode surfaces and interfaces. • Ageing and fatigue of layered oxide Li-ion battery cathode materials from the atomistic point of view. • Defect formation and electronic structure evolution as causes for cathode degradation. • Significance of interfacial energy alignment and contact potential for side reactions. - Abstract: This overview addresses the atomistic aspects of degradation of layered LiMO2 (M = Ni, Co, Mn) oxide Li-ion battery cathode materials, aiming to shed light on the fundamental degradation mechanisms especially inside active cathode materials and at their interfaces. It includes recent results obtained by novel in situ/in operando diffraction methods, modelling, and quasi in situ surface science analysis. Degradation of the active cathode material occurs upon overcharge, resulting from a positive potential shift of the anode. Oxygen loss and eventual phase transformation resulting in dead regions are ascribed to changes in electronic structure and defect formation. The anode potential shift results from loss of free lithium due to side reactions occurring at electrode/electrolyte interfaces. Such side reactions are caused by electron transfer, and depend on the electron energy level alignment at the interface. Side reactions at electrode/electrolyte interfaces and capacity fade may be overcome by the use of suitable solid-state electrolytes and Li-containing anodes

  20. Fundamental degradation mechanisms of layered oxide Li-ion battery cathode materials: Methodology, insights and novel approaches

    Energy Technology Data Exchange (ETDEWEB)

    Hausbrand, R., E-mail: hausbrand@surface.tu-darmstadt.de; Cherkashinin, G.; Ehrenberg, H.; Gröting, M.; Albe, K.; Hess, C.; Jaegermann, W.

    2015-02-15

    Graphical abstract: - Highlights: • Description of recent in operando and in situ analysis methodology. • Surface science approach using photoemission for analysis of cathode surfaces and interfaces. • Ageing and fatigue of layered oxide Li-ion battery cathode materials from the atomistic point of view. • Defect formation and electronic structure evolution as causes for cathode degradation. • Significance of interfacial energy alignment and contact potential for side reactions. - Abstract: This overview addresses the atomistic aspects of degradation of layered LiMO{sub 2} (M = Ni, Co, Mn) oxide Li-ion battery cathode materials, aiming to shed light on the fundamental degradation mechanisms especially inside active cathode materials and at their interfaces. It includes recent results obtained by novel in situ/in operando diffraction methods, modelling, and quasi in situ surface science analysis. Degradation of the active cathode material occurs upon overcharge, resulting from a positive potential shift of the anode. Oxygen loss and eventual phase transformation resulting in dead regions are ascribed to changes in electronic structure and defect formation. The anode potential shift results from loss of free lithium due to side reactions occurring at electrode/electrolyte interfaces. Such side reactions are caused by electron transfer, and depend on the electron energy level alignment at the interface. Side reactions at electrode/electrolyte interfaces and capacity fade may be overcome by the use of suitable solid-state electrolytes and Li-containing anodes.

  1. Production of Quasicomposite Surface Layer of a Metal Material by Shock Wave Strain Hardening

    Directory of Open Access Journals (Sweden)

    A.V. Kirichek

    2014-07-01

    Full Text Available Quite often in order to improve the performance of a product it is necessary to form a strengthened structure that will be extremely hard and have good plasticity at the same time. One way to meet this challenge is to apply shock wave mechanical hardening to produce micro- or nanocrystalline heterogeneous structures in homogeneous metals or alloys. A peculiar feature of such structure is its layer-by-layer formation with smooth transition between hard and plastic areas, which improves the performance of the strengthened item significantly

  2. Nano-sized structured layered positive electrode materials to enable high energy density and high rate capability lithium batteries

    Science.gov (United States)

    Deng, Haixia; Belharouak, Ilias; Amine, Khalil

    2012-10-02

    Nano-sized structured dense and spherical layered positive active materials provide high energy density and high rate capability electrodes in lithium-ion batteries. Such materials are spherical second particles made from agglomerated primary particles that are Li.sub.1+.alpha.(Ni.sub.xCo.sub.yMn.sub.z).sub.1-tM.sub.tO.sub.2-dR.sub.d- , where M is selected from can be Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, Zr, or a mixture of any two or more thereof, R is selected from F, Cl, Br, I, H, S, N, or a mixture of any two or more thereof, and 0.ltoreq..alpha..ltoreq.0.50; 0materials and their use in electrochemical devices are also described.

  3. A Monte Carlo code for simulating soft X-ray absorption in pure and two-layer materials

    International Nuclear Information System (INIS)

    The present paper describes a Monte Carlo code to simulate the cascade of electron-hole pairs and phonons generated when a low-energy X-ray photon is absorbed by a material. The model has been applied to study the response to UV or soft X-ray radiation of diamond and silicon, focused on the case of two-layer material made of diamond film grown on silicon. Typically the statistical distribution of the electron-hole cascade is macroscopically parameterized by the mean energy required to create an electron-hole pair W and the Fano factor F. The results for the pure materials are in agreement with the values present in the literature. Moreover we found an enhancement of the Fano factor and a super-Poissonian behaviour of the statistical distribution of the pairs, typical of correlated systems.

  4. Controllable fabrication of nanostructured materials for photoelectrochemical water splitting via atomic layer deposition.

    Science.gov (United States)

    Wang, Tuo; Luo, Zhibin; Li, Chengcheng; Gong, Jinlong

    2014-11-21

    Photoelectrochemical (PEC) water splitting is an attractive approach to generate hydrogen as a clean chemical fuel from solar energy. But there remain many fundamental issues to be solved, including inadequate photon absorption, short carrier diffusion length, surface recombination, vulnerability to photo-corrosion, and unfavorable reaction kinetics. Owing to its self-limiting surface reaction mechanism, atomic layer deposition (ALD) is capable of depositing thin films in a highly controllable manner, which makes it an enabling technique to overcome some of the key challenges confronted by PEC water splitting. This tutorial review describes some unique and representative applications of ALD in fabricating high performance PEC electrodes with various nanostructures, including (i) coating conformal thin films on three-dimensional scaffolds to facilitate the separation and migration of photocarriers and enhance light trapping, as well as realizing controllable doping for bandgap engineering and forming homojunctions for carrier separation; (ii) achieving surface modification through deposition of anti-corrosion layers, surface state passivation layers, and surface catalytic layers; and (iii) identifying the main rate limiting steps with model electrodes with highly defined thickness, composition, and interfacial structure. PMID:24500041

  5. Trapping and depth profile of tritium in surface layers of metallic materials

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, M., E-mail: masao@ctg.u-toyama.ac.jp [Hydrogen Isotope Research Center, University of Toyama, Gofuku 3190, Toyama 930-8555 (Japan); Chen, Z. [The Southwestern Institute of Physics, Chengdu 610041, Sichuan (China); Nisimura, K. [National Institute for Fusion Science, Toki 509-5292 (Japan); Akamaru, S.; Torikai, Y.; Hatano, Y. [Hydrogen Isotope Research Center, University of Toyama, Gofuku 3190, Toyama 930-8555 (Japan); Ashikawa, N. [National Institute for Fusion Science, Toki 509-5292 (Japan); Oya, Y.; Okuno, K. [Radiochemistry Research Laboratory, Shizuoka University, Shizuoka 422-8529 (Japan); Hino, T. [Laboratory of Plasma Physics and Engineering, Hokkaido University, Sapporo 060-8628 (Japan)

    2011-10-01

    Tritium amount retained in surface layers and release behavior from surface layers were examined using SS316L samples exposed to plasmas in the Large Helical Device and a commercial Cu-Be alloy plate. BIXS analyses and observation by SEM indicate that carbon and titanium deposited on the plasma-facing surface of the SS316L samples. Larger amount of tritium was trapped in the plasma-facing surface in comparison with the polished surface. Higher enrichment of tritium in surface layers was similarly found in the polished surface of both samples. The amount of surface tritium in both samples was almost same, while the bulk concentration of tritium in Cu-Be was much lower than that in SS316L. Tritium release from the SS316L and Cu-Be samples into water was examined by immersion experiments. Tritium elution was observed for both samples, but changes in the residual tritium amount in surface layers were different from each other.

  6. Highly condensed fluorinated methacrylate hybrid material for transparent low-kappa passivation layer in LCD-TFT.

    Science.gov (United States)

    Oh, Ji-Hoon; Kwak, Seung-Yeon; Yang, Seung-Cheol; Bae, Byeong-Soo

    2010-03-01

    Photocurable and highly condensed fluorinated methacrylate oligosiloxane, with a low dielectric constant (kappa = 2.54), was prepared by a nonhydrolytic sol-gel condensation reaction. The oligosiloxane resin was then spin-coated, photocured, and thermally baked in order to fabricate a fluorinated methacrylate hybrid material (FM hybrimer) thin film. This study investigated the application of this FM hybrimer film as a low-kappa passivation layer in LCD-based thin film transistors (TFT). It was found that a dielectric constant as low as kappa = 2.54 could be obtained, without introducing pores in the dense FM hybrimer films. This study compares FM hybrimer film characteristics with those required for passivation layers in LCD-TFTs, including thermal stability, optical transmittance, hydrophobicity, gap fill, and planarization effects as well as electrical insulation. PMID:20356298

  7. New hybrid material based on layered double hydroxides and biogenic silver nanoparticles: antimicrobial activity and cytotoxic effect

    Scientific Electronic Library Online (English)

    Priscyla D., Marcato; Natália V., Parizotto; Diego Stéfani T., Martinez; Amauri J., Paula; Iasmin R., Ferreira; Patrícia S., Melo; Nelson, Durán; Oswaldo L., Alves.

    2013-02-01

    Full Text Available Hidróxidos duplos lamelares (HDLs) têm sido amplamente investigados devido às suas diversas aplicações nas indústrias de materiais e biotecnologia. A combinação de nanopartículas de prata com o material biocompatível HDL pode criar um novo material híbrido com novas propriedades sinergísticas. Neste [...] trabalho, nanopartículas de prata biogênicas (AgNPbio) foram associadas com Mg-Al HDL para obter o material híbrido HDL-AgNPbio. O novo material híbrido obtido foi caracterizado por difratometria de raios X (XRD), microscopias eletrônica de transmissão (TEM) e de varredura com espectroscopia de energia dispersiva por raios-X (MEV-EDS), espectrometria de emissão atômica por plasma acoplado indutivamente (ICP-OES) e espectroscopia na região do infravermelho com transformada de Fourier (FTIR). O HDL foi eficiente em adsorver nanopartículas de prata devido à carga superficial oposta entre as AgNPbio (? = -13,2 mV) e o HDL (? = +3,2 mV). Além disso, as AgNPbio não foram lixiviadas do material híbrido, mesmo após cinco ciclos de lavagem, indicando uma forte interação. Uma importante propriedade deste material híbrido foi a sua atividade antimicrobiana contra Staphylococcus aureus e Escherichia coli e ausência de efeito citotóxico em células de fibroblastos (V79). Este material híbrido é um interessante e promissor nanobiocompósito para aplicações biomédicas e cosméticas. Abstract in english Layered double hydroxides (LDHs) have been widely investigated due to their several applications in the material and biotechnology industries. The combination of silver nanoparticles with biocompatible LDH material can create a new hybrid material with new properties. In this work, biogenic silver n [...] anoparticles (AgNPbio) were associated with Mg-Al LDH to obtain the hybrid material LDH-AgNPbio. The new hybrid material obtained was characterized by X-ray diffractometry (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectrometry (ICP-OES) and Fourier transform infrared spectroscopy (FTIR). LDH was efficient to absorb silver nanoparticles due to an opposite surface charge between AgNPbio (? = -13.2 mV) and LDH (? = +3.2 mV). Furthermore, AgNPbio was not lixiviated from LDH-AgNPbio, even after five washes, indicating a strong interaction. An important property of this hybrid material was its antimicrobial activity against Staphylococcus aureus and Escherichia coli and absence of cytotoxic effect to fibroblast cell (V79). This hybrid material is an interesting and promising nanobiocomposite for biomedical and cosmetic applications.

  8. Fixed, Fluid, and Transient: Negotiating Layers of Art Classroom Material Culture

    Science.gov (United States)

    Woywod, Christine

    2015-01-01

    Objects of material culture have meaning. American flags, worktables, bulletin boards, interactive whiteboards, and large white-faced clocks signify "classroom" while color wheels, cupboards, cabinets, sinks, drawing supplies, and that particular scent that lingers after years of exposure to painting materials even more specifically…

  9. A sparse digital signal model for ultrasonic nondestructive evaluation of layered materials.

    Science.gov (United States)

    Bochud, N; Gomez, A M; Rus, G; Peinado, A M

    2015-09-01

    Signal modeling has been proven to be an useful tool to characterize damaged materials under ultrasonic nondestructive evaluation (NDE). In this paper, we introduce a novel digital signal model for ultrasonic NDE of multilayered materials. This model borrows concepts from lattice filter theory, and bridges them to the physics involved in the wave-material interactions. In particular, the proposed theoretical framework shows that any multilayered material can be characterized by a transfer function with sparse coefficients. The filter coefficients are linked to the physical properties of the material and are analytically obtained from them, whereas a sparse distribution naturally arises and does not rely on heuristic approaches. The developed model is first validated with experimental measurements obtained from multilayered media consisting of homogeneous solids. Then, the sparse structure of the obtained digital filter is exploited through a model-based inverse problem for damage identification in a carbon fiber-reinforced polymer (CFRP) plate. PMID:26092090

  10. Multi-layered organic light-emitting diode fabrication using low molecular weight materials by electrospray method

    International Nuclear Information System (INIS)

    Active technology development efforts to improve the productivity of organic light emitting diode (OLED) fabrication using wet processes based on ink-jet technology have been conducted by taking advantage of the low cost and large area processability of organic materials. However, OLEDs formed by conventional wet processes have been unable to reproduce the high performance levels of OLEDs that were mass-produced by dry processes based on vacuum deposition. We have therefore focused on the electrospray (ES) method as a potential fabrication technology. In this paper, we report on a multilayer thin-film fabrication process with low molecular-weight materials using an ES method that allows atomization of the organic materials by Coulomb repulsion and successive adhesion of solid-state multi-layered thin films. We demonstrate OLED fabrication by this ES method and the characteristics of the resulting devices. - Highlights: • We fabricated multilayers of small organic molecules using electrospray (ES) method. • ES method allows a film formation without erosion of the underlying organic layers. • We evaluate the characteristics of OLEDs fabricated by ES method

  11. Flexible n-type thermoelectric materials by organic intercalation of layered transition metal dichalcogenide TiS2

    Science.gov (United States)

    Wan, Chunlei; Gu, Xiaokun; Dang, Feng; Itoh, Tomohiro; Wang, Yifeng; Sasaki, Hitoshi; Kondo, Mami; Koga, Kenji; Yabuki, Kazuhisa; Snyder, G. Jeffrey; Yang, Ronggui; Koumoto, Kunihito

    2015-06-01

    Organic semiconductors are attracting increasing interest as flexible thermoelectric materials owing to material abundance, easy processing and low thermal conductivity. Although progress in p-type polymers and composites has been reported, their n-type counterpart has fallen behind owing to difficulties in n-type doping of organic semiconductors. Here, we present an approach to synthesize n-type flexible thermoelectric materials through a facile electrochemical intercalation method, fabricating a hybrid superlattice of alternating inorganic TiS2 monolayers and organic cations. Electrons were externally injected into the inorganic layers and then stabilized by organic cations, providing n-type carriers for current and energy transport. An electrical conductivity of 790 S cm-1 and a power factor of 0.45 mW m-1 K-2 were obtained for a hybrid superlattice of TiS2/[(hexylammonium)x(H2O)y(DMSO)z], with an in-plane lattice thermal conductivity of 0.12 ± 0.03 W m-1 K-1, which is two orders of magnitude smaller than the thermal conductivities of the single-layer and bulk TiS2. High power factor and low thermal conductivity contributed to a thermoelectric figure of merit, ZT, of 0.28 at 373 K, which might find application in wearable electronics.

  12. Flexible n-type thermoelectric materials by organic intercalation of layered transition metal dichalcogenide TiS2.

    Science.gov (United States)

    Wan, Chunlei; Gu, Xiaokun; Dang, Feng; Itoh, Tomohiro; Wang, Yifeng; Sasaki, Hitoshi; Kondo, Mami; Koga, Kenji; Yabuki, Kazuhisa; Snyder, G Jeffrey; Yang, Ronggui; Koumoto, Kunihito

    2015-06-01

    Organic semiconductors are attracting increasing interest as flexible thermoelectric materials owing to material abundance, easy processing and low thermal conductivity. Although progress in p-type polymers and composites has been reported, their n-type counterpart has fallen behind owing to difficulties in n-type doping of organic semiconductors. Here, we present an approach to synthesize n-type flexible thermoelectric materials through a facile electrochemical intercalation method, fabricating a hybrid superlattice of alternating inorganic TiS2 monolayers and organic cations. Electrons were externally injected into the inorganic layers and then stabilized by organic cations, providing n-type carriers for current and energy transport. An electrical conductivity of 790 S cm(-1) and a power factor of 0.45 mW m(-1) K(-2) were obtained for a hybrid superlattice of TiS2/[(hexylammonium)x(H2O)y(DMSO)z], with an in-plane lattice thermal conductivity of 0.12 ± 0.03 W m(-1) K(-1), which is two orders of magnitude smaller than the thermal conductivities of the single-layer and bulk TiS2. High power factor and low thermal conductivity contributed to a thermoelectric figure of merit, ZT, of 0.28 at 373 K, which might find application in wearable electronics. PMID:25849369

  13. Nanostructured layers of anion-defective gamma–alumina – New perspective TL and OSL materials for skin dosimetry. Preliminary results

    International Nuclear Information System (INIS)

    Thin- layer material based on nanostructured Al2O3 of the surface density 5 mg/cm2 was obtained. The material is characterized by high OSL and TL yields comparable with those for TLD-500 which is one of the leaders among the TL and OSL detectors. The dose response, fading and dependence of TL yield on heating rate was studied. It is established that high luminescence yield of the samples under study correlates with the content of anion vacancies and ?-phase of Al2O3. The data for time-resolved luminescent spectroscopy are presented, which evidence for possible correlation between high TL and OSL activity and the F-type centers. It is noted that the material needs to be modified for successful use in dosimetry. In addition further studies to decrease the contribution of unstable (at 300 K) components to OSL and TL yields are required. - Highlights: • Thin nanostructured layers (TNL) of Al2O3 with thickness of 5 mg/cm2 were obtained. • Its TL and OSL yields are related to contents of ?-phase and anion vacancies. • Dose response of TNL shows linear behavior in a range of 10–5000 mGy. • Luminescence properties of TNL are similar to such of anion-defective corundum. • These properties are associated with centers of F-type

  14. Bulk and surface acoustic waves in solid-fluid Fibonacci layered materials.

    Science.gov (United States)

    Quotane, I; El Boudouti, E H; Djafari-Rouhani, B; El Hassouani, Y; Velasco, V R

    2015-08-01

    We study theoretically the propagation and localization of acoustic waves in quasi-periodic structures made of solid and fluid layers arranged according to a Fibonacci sequence. We consider two types of structures: either a given Fibonacci sequence or a periodic repetition of a given sequence called Fibonacci superlattice. Various properties of these systems such as: the scaling law and the self-similarity of the transmission spectra or the power law behavior of the measure of the energy spectrum have been highlighted for waves of sagittal polarization in normal and oblique incidence. In addition to the allowed modes which propagate along the system, we study surface modes induced by the surface of the Fibonacci superlattice. In comparison with solid-solid layered structures, the solid-fluid systems exhibit transmission zeros which can break the self-similarity behavior in the transmission spectra for a given sequence or induce additional gaps other than Bragg gaps in a periodic structure. PMID:25819878

  15. Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses

    DEFF Research Database (Denmark)

    Stöhr, Frederik; Michael-Lindhard, Jonas

    2015-01-01

    This article describes the realization of complex high-aspect ratio silicon structures with feature dimensions from 100 lm to 100nm by deep reactive ion etching using the Bosch process. As the exact shape of the sidewall profiles can be crucial for the proper functioning of a device, the authors investigated how sacrificial structures in the form of guarding walls and pillars may be utilized to facilitate accurate control of the etch profile. Unlike other sacrificial structuring approaches, no silicon-on-insulator substrates or multiple lithography steps are required. In addition, the safe removal of the sacrificial structures was accomplished by thermal oxidation and subsequent selective wet etching. The effects of the dimensions and relative placement of sacrificial walls and pillars on the etching result were determined through systematic experiments. The authors applied this process for exact sidewall control in the manufacture of x-ray lenses that are very sensitive to sidewall shape nonuniformities. Compound kinoform lenses for focusing hard x-rays with structure heights of 200 lm were manufactured, and the lenses were tested in terms of their focusing ability and refracting qualities using synchrotron radiation at a photon energy of 17 keV. A 180 lm long line focus with a waist of 430 nm at a focal length of 215mm was obtained.

  16. Preparation and Characterization of TiO2/CdS Layers as Potential Photoelectrocatalytic Materials

    Directory of Open Access Journals (Sweden)

    Teofil-Danut Silipas

    2011-01-01

    Full Text Available The TiO2/CdS semiconductor composites were prepared on
    indium tin oxide (ITO substrates in di®erent mass proportions via wet-chemical techniques using bi-distilled water, acetyl-acetone, poly-propylene-glycol and Triton X-100 as additives. The composite layers were annealed in normal conditions at the temperature of 450±C, 120 min. with a rate of temperature increasing of 5±C/min. The structural and optical properties of all the TiO2/CdS ayers were characterized by X-ray di®raction, UV-VIS spectroscopy, spectrofluorimetry and FT/IR microscopy. The microstructural properties of the deposited TiO2/CdS layers can be modi¯ed by varying the mass proportions of TiO2:CdS. The good crystallinity level and the high optical adsorption of
    the TiO2/CdS layers make them attractive for photoelectrochemical cell applications.

  17. Characterization of candidate materials in SCWR conditions - Estimation of kinetic parameters of individual corrosion layer constituents

    International Nuclear Information System (INIS)

    Understanding of corrosion phenomena of candidate materials under SCWR (Supercritical Water Reactor) conditions necessitates a reliable experimental testing of such materials and also a development of modelling techniques for the relevant conditions. The long term objective of this work is to perform a study that would serve as a guide for the selection of in-core materials for the European HPLWR (High Performance Light Water Reactor). One of the key performance indicators for the material selection is the corrosion and oxidation behaviour of materials in SCWR conditions. Therefore, a combination of in-situ studies with ex-situ analytical characterisation of the oxide films forming on the internal component candidate materials in contact with supercritical water are needed. In the present paper, a first step towards employing a model for the in-depth contents of individual metallic constituents (i.e. Fe, Cr, Ni, Mn) to estimate the kinetic and transport parameters of the oxidation process in SCWR conditions is performed. A preliminary description of the model concept and the calculation procedure for ferritic-martensitic (F/M) steel P91 and austenitic stainless steel AISI 316L(NG) are presented. For the purpose, selected material samples were analyzed using glow discharge optical emission spectroscopy (GDOES) and scanning electron microscopy (SEM) to determine the in-depth composition of the formed oxides. (authors)

  18. Bonding Semiconductor Laser Chips : Substrate Material Figure of Merit and Die Attach Layer Influence

    OpenAIRE

    Pliska, A.-C.; Mottin, J.; Matuschek, N.; Bosshard, C.

    2005-01-01

    The coefficient of thermal expansion (CTE) and the thermal conductivity are the two key parameters to consider when selecting a particular substrate material for a die bonding process. We will discuss here a model to determine the substrate material giving the best chip reliability expectations for GaAs and InP laser chips. In that respect, a comparison of the thermo-mechanical stresses induced during the soldering process of GaAs and InP semiconductor chips on different substrate materials u...

  19. Preliminary Study on Piezoresistive and Piezoelectric Properties of a Double-layer Soft Material for Tactile Sensing

    Directory of Open Access Journals (Sweden)

    Weiting LIU

    2015-07-01

    Full Text Available This paper describes a double-layer simplified sensor unit with interesting electromechanical properties, which consists of a film made from multiwalled carbon nanotube (MWNT mixed by polymer composite and a thin film of polyvinylidene fluoride (PVDF. It is envisaged to imitate the distributed tactile receptors of human hands so as to help the disabled to recover the basic tactile perception. This paper shows the fabrication and performance research of such a new piezoelectric-piezoresistive composite material, which indicates a promising application in prosthetic hand.

  20. Theory of the axi-symmetric extrusion process of multi-layer materials with a strong plastic nonhomogeneity

    OpenAIRE

    J. Piwnik; A. Patejuk

    2008-01-01

    A novel simplified r hcorctical solution is found lor thc strcss starcs accompanying thc proccss of cxt ri~siono f ma![ i-laycr matcrialsunder rhc conditions af axial symmetry. Thc solution i~ bawd nn ~ h mc n dcl of pcrfcct plastic material satisfying thc Trcsca yicld condition.thc Haar-Karman conditions bcing sntisficd in each layer. Thc laycrs arc chnnctcrizcd by difrercnt yicld limits and stmng plasticnonhomogeneity. In thc ncighhoi~rhoorol f thc interfaces conrinuous variation of rhc yic...

  1. Localized corrosion of metallic materials and ? radiation effects in passive layers under simulated radwaste repository conditions. Final report

    International Nuclear Information System (INIS)

    The task of the project was to simulate the conditions in a radwaste repository and to perform local analyses in order to detect the critical conditions and material susceptibilities leading to localized corrosion of materials. The information thus obtained was to yield more precise data on the long-term stability of materials for the intended purpose, in order to be able to appropriately select or optimize the materials (Ti, TiO.2Pd, Hastelloy C4, fine-grained structural steel). A major aspect to be examined was natural inhomogeneities of the electrode surfaces, as determined by the grain structure of the selected materials. Thus a laterally inhomogeneous composition in the welded zone induces an inhomogeneous current distribution, and hence strong susceptibility to localized corrosion. This effect was to be quantified, and the localized corrosion processes had to be identified by means of novel, electrochemical methods with a resolution power of ?m. The investigations were to be made under conditions as near to practice as possible, for instance by simulating radwaste repository conditions and performing measurements at elevated temperatures (170 C) in an autoclave. Another task was to examine the radiation effects of ? radiation on passive layers, and describe the possible modifications induced by recrystallisation, photocorrosion, or oxide formation. (orig./MM)

  2. New efficient electrochemical synthesis of 1,5-dithioxylopyranosides in the presence of a sacrificial anode.

    Science.gov (United States)

    Brevet, David; Mugnier, Yves; Samreth, Soth; Dellis, Philippe

    2003-07-22

    Electroreduction of the disulfide derivative RSSR (5, R= [bond]C(6)H(4)[bond]CO[bond]C(6)H(4)[bond]CN) on a mercury pool or a carbon gauze electrode in the presence of 2,3,4-tri-O-acetyl-5-thio-D-xylopyranosyl bromide (1), using a sacrificial zinc anode gave an alpha,beta anomeric mixture of [4-(4-cyanobenzoylphenyl)] 2,3,4-tri-O-acetyl-1,5-dithio-D-xylopyranoside (6) in 40-70% yield, according to the experimental conditions used (nature of solvent, electrolyte salt, and temperature). High selectivity favouring the alpha anomer of 6 is observed starting from the alpha anomer of 1. Mechanistic aspects are discussed. PMID:12860425

  3. De un sendero sacrificial surcado de goce // from a sacrificed path plow through of pleasure

    Directory of Open Access Journals (Sweden)

    Mario Orozco Guzmán

    2011-06-01

    Full Text Available El presente trabajo discierne un semblante maldito del sacrificio. En nombre del amor se ha idealizado el sacrificio como paradigma de su audacia y heroísmo, mientras la cultura se ha encargado de enaltecer la proeza sacrificial como puesta en acto del amor. El destinatario de esta inmolación suprema inscribe la producción del goce divino en calidad de objeto “a”, tal como lo revelan sacrificios paradigmáticos presentes en la historia y la literatura. // The current work discerns a cursed countenance from the sacrifice. The sacrifice has been idealized in love's name, as paradigm of its courage and heroism, meanwhile the culture has taken charge of dignifying the sacrificed feat as event in the love act. The addressee of this supreme immolation registers the production of the divine enjoyment as “a” object, just as it is revealed by paradigmatic sacrifices present on history and literature.

  4. Sacrificial limbs of sovereignty: disabled veterans, masculinity, and nationalist politics in Turkey.

    Science.gov (United States)

    Açiksöz, Salih Can

    2012-03-01

    Over the last decade, disabled veterans of the Turkish Army who were injured while fighting against the Partiya Karkerên Kurdistan (PKK; Kurdistan Workers' Party) have become national icons and leading ultranationalist actors. While being valorized as sacrificial heroes in nationalist discourse, they have also confronted socioeconomic marginalization, corporeal otherness, and emasculation anxieties. Against this backdrop, disabled veterans' organizations have become the locus of an ultranationalist campaign against dissident intellectuals. Building on two years of ethnographic research with disabled veterans in Turkey, this article analyzes these processes through the analytical lens of the body. Locating the disabled veteran body at the intersection of state welfare practices, nationalist discourses on heroism and sacrifice, and cultural norms of masculinity and disability, I illustrate how disabled veterans' gendered and classed experiences of disability are hardened into a political identity. Consequently, I show how violence generates new modalities of masculinity and political agency through its corporeal effects. PMID:22574389

  5. Enhanced photon absorption in spiral nanostructured solar cells using layered 2D materials.

    Science.gov (United States)

    Tahersima, Mohammad H; Sorger, Volker J

    2015-08-28

    Recent investigations of semiconducting two-dimensional (2D) transition metal dichalcogenides have provided evidence for strong light absorption relative to its thickness attributed to high density of states. Stacking a combination of metallic, insulating, and semiconducting 2D materials enables functional devices with atomic thicknesses. While photovoltaic cells based on 2D materials have been demonstrated, the reported absorption is still just a few percent of the incident light due to their sub-wavelength thickness leading to low cell efficiencies. Here we show that taking advantage of the mechanical flexibility of 2D materials by rolling a molybdenum disulfide (MoS(2))/graphene (Gr)/hexagonal boron nitride stack to a spiral solar cell allows for optical absorption up to 90%. The optical absorption of a 1 ?m long hetero-material spiral cell consisting of the aforementioned hetero stack is about 50% stronger compared to a planar MoS(2) cell of the same thickness; although the volumetric absorbing material ratio is only 6%. A core-shell structure exhibits enhanced absorption and pronounced absorption peaks with respect to a spiral structure without metallic contacts. We anticipate these results to provide guidance for photonic structures that take advantage of the unique properties of 2D materials in solar energy conversion applications. PMID:26235027

  6. Simulation of Sputtering Damage of Tungsten Coating Layer on First Wall Materials of a Fusion Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunmyung; Lee, Ho Jung; Jang, Changheui [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    First Wall (FW) structural materials of fusion reactors, such as International Thermonuclear Experimental Reactor (ITER), are subjected to transient loads (disruptions, ELMs, and VDE) resulting in the loss of integrity from erosion/deposition processes. The dominant mechanism for erosion of Plasma Facing Component (PFC) materials is sputtering by which atoms from the surface of solid are ejected due to interaction with energetic plasma ions. Simulation of such trajectories of ions is used to calculate sputtering yields further estimating lifetime of materials. Tungsten coating on FW materials such as tungsten (W) and Carbon Fiber Composites (CFC) has been considered to compensate for this loss of eroded materials. In this study, a computational simulation of sputtering of W coating on W and CFC target was performed to incorporate physical interpretation of impact of coating density and surface binding energy (adhesion) on target damage behaviors. In variation of tungsten coating density, TRIM simulation on 3D target damage on tungsten substrate is carried out. For the higher coating density, the less target damage occurs. Surface binding energy modification seems to have no effect on sputtering yield of coating at all. Balancing of coating density and adhesion needs to be optimized Experimental validation of such results is to carry out for FW candidate target materials such as CFC and W by PS and PVD coating technique.

  7. Enhanced photon absorption in spiral nanostructured solar cells using layered 2D materials

    Science.gov (United States)

    Tahersima, Mohammad H.; Sorger, Volker J.

    2015-08-01

    Recent investigations of semiconducting two-dimensional (2D) transition metal dichalcogenides have provided evidence for strong light absorption relative to its thickness attributed to high density of states. Stacking a combination of metallic, insulating, and semiconducting 2D materials enables functional devices with atomic thicknesses. While photovoltaic cells based on 2D materials have been demonstrated, the reported absorption is still just a few percent of the incident light due to their sub-wavelength thickness leading to low cell efficiencies. Here we show that taking advantage of the mechanical flexibility of 2D materials by rolling a molybdenum disulfide (MoS2)/graphene (Gr)/hexagonal boron nitride stack to a spiral solar cell allows for optical absorption up to 90%. The optical absorption of a 1 ?m long hetero-material spiral cell consisting of the aforementioned hetero stack is about 50% stronger compared to a planar MoS2 cell of the same thickness; although the volumetric absorbing material ratio is only 6%. A core-shell structure exhibits enhanced absorption and pronounced absorption peaks with respect to a spiral structure without metallic contacts. We anticipate these results to provide guidance for photonic structures that take advantage of the unique properties of 2D materials in solar energy conversion applications.

  8. Thermal shock problem of a generalized thermoelastic layered composite material with variable thermal conductivity

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The dynamic treatment of one-dimensional generalized thermoelastic problem of heat conduction is made for a layered thin plate which is exposed to a uniform thermal shock taking into account variable thermal conductivity. The basic equations are transformed by Laplace transform and solved by a direct method. The solution was applied for a plate of sandwich structure, which is thermally shocked, and is traction-free in the outer sides. The inverses of Laplace transforms are obtained numerically. The temperature, the stress, and the displacement distributions are represented graphically.

  9. Engineering topological superconductors using surface atomic-layer/molecule hybrid materials

    Science.gov (United States)

    Uchihashi, Takashi

    2015-08-01

    Surface atomic-layer (SAL) superconductors consisting of epitaxially grown metal adatoms on a clean semiconductor surface have been recently established. Compared to conventional metal thin films, they have two important features: (i) space-inversion symmetry-breaking throughout the system and (ii) high sensitivity to surface adsorption of foreign species. These potentially lead to manifestation of the Rashba effect and a Zeeman field exerted by adsorbed magnetic organic molecules. After introduction of the archetypical SAL superconductor Si(111)-(?7 × ?3)-In, we describe how these features are utilized to engineer a topological superconductor with Majorana fermions and discuss its promises and expected challenges.

  10. Preparation and Characterization of TiO2/CdS Layers as Potential Photoelectrocatalytic Materials

    OpenAIRE

    Teofil-Danut Silipas; Ioan Bratu; Simina-Virginia Dreve; Ramona-Crina Suciu; Marcela-Corina Rosu; Emil Indrea

    2011-01-01

    The TiO2/CdS semiconductor composites were prepared on
    indium tin oxide (ITO) substrates in di®erent mass proportions via wet-chemical techniques using bi-distilled water, acetyl-acetone, poly-propylene-glycol and Triton X-100 as additives. The composite layers were annealed in normal conditions at the temperature of 450±C, 120 min. with a rate of temperature increasing of 5±C/min. The structural and optical properties of all the TiO2/CdS ayers were ch...

  11. Transport properties of Layer-Antiferromagnet CuCrS2: A possible thermoelectric material

    OpenAIRE

    Tewari, G. C.; Tripathi, T S; Rastogi, A. K.

    2009-01-01

    The electrical, thermal conductivity and Seebeck coefficient of the quenched, annealed and slowly cooled phases of the layer compound CuCrS2 have been reported between 15K to 300K. We also confirm the antiferromagnetic transition at 40K in them by our magnetic measurements between 2K and 300K. The crystal flakes show a minimum around 100K in their in-plane resistance behavior. For the polycrystalline pellets the resistivity depends on their flaky texture and it attains at mo...

  12. Stacking and Registry Effects in Layered Materials: The Case of Hexagonal Boron Nitride

    OpenAIRE

    Marom, Noa; Bernstein, Jonathan; Garel, Jonathan; Tkatchenko, Alexandre; Joselevich, Ernesto; Kronik, Leeor; Hod, Oded

    2010-01-01

    The interlayer sliding energy landscape of hexagonal boron nitride (h-BN) is investigated via a van der Waals corrected density functional theory approach. It is found that the main role of the van der Waals forces is to "anchor" the layers at a fixed distance, whereas the electrostatic forces dictate the optimal stacking mode and the interlayer sliding energy. A nearly free-sliding path is identified, along which bandgap modulations of ~0.6 eV are obtained. We propose a sim...

  13. Aligned carbon nanotube film enables thermally induced state transformations in layered polymeric materials.

    Science.gov (United States)

    Lee, Jeonyoon; Stein, Itai Y; Kessler, Seth S; Wardle, Brian L

    2015-04-29

    The energy losses and geometric constraints associated with conventional curing techniques of polymeric systems motivate the study of a highly scalable out-of-oven curing method using a nanostructured resistive heater comprised of aligned carbon nanotubes (A-CNT). The experimental results indicate that, when compared to conventional oven based techniques, the use of an "out-of-oven" A-CNT integrated heater leads to orders of magnitude reductions in the energy required to process polymeric layered structures such as composites. Integration of this technology into structural systems enables the in situ curing of large-scale polymeric systems at high efficiencies, while adding sensing and control capabilities. PMID:25872577

  14. Forward problem of resonant ultrasound spectroscopy for identification of material properties of thin layers.

    Czech Academy of Sciences Publication Activity Database

    Kruisová, Alena; R?žek, M.; Sedlák, Petr; Seiner, Hanuš; Landa, Michal; Kolman, Radek

    Pilsen : University of West Bohemia, Pilsen, 2010 - (Adámek, V.; Zají?ek, M.). s. 1-2 ISBN 978-80-7043-919-7. [Conference with international parcipationCM 2010 /26./. 08.11.2010-10.11.2010, Ne?tiny] R&D Projects: GA ?R(CZ) GA101/09/0702 Institutional research plan: CEZ:AV0Z20760514 Keywords : resonant ultrasound spectroscopy (RUS) * elastic properties of thin layers Subject RIV: BI - Acoustics http://www.kme.zcu.cz/vm2010

  15. A functionalized phosphonate-rich organosilica layered hybrid material (PSLM) fabricated through a mild process for heavy metal uptake

    Energy Technology Data Exchange (ETDEWEB)

    Daikopoulos, Chris [Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110 (Greece); Bourlinos, Athanasios B. [Institute of Materials Science, NCSR “Demokritos”, Ag. Paraskevi Attikis, Athens 15310 (Greece); Georgiou, Yiannis [Laboratory of Physical Chemistry, Department of Environmental and Natural Resources Management, University of Patras, Seferi 2, Agrinio 30100 (Greece); Deligiannakis, Yiannis, E-mail: ideligia@cc.uoi.gr [Laboratory of Physical Chemistry, Department of Environmental and Natural Resources Management, University of Patras, Seferi 2, Agrinio 30100 (Greece); Zboril, Radek [Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry and Experimental Physics, Palacky University, Olomouc 77146 (Czech Republic); Karakassides, Michael A. [Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110 (Greece)

    2014-04-01

    Highlights: • Novel phosphonate-rich organosilica layered hybrid material (PSLM) fabricated through a mild xerogel process. • Surface Complexation Modeling reveals that PSLM bears 2 types of functional groups able to bind heavy metal. • Maximum metal uptake capacities were found 2.72 mmol g{sup ?1} for Cu{sup 2+}, 1.67 mmol g{sup ?1} for Pb{sup 2+} and 1.00 mmol g{sup ?1} for Cd{sup 2+} at pH 7. • EPR spectroscopy reveals local coordination environment for Cu{sup 2+} ions. - Abstract: A phosphonate-rich organosilica layered hybrid material (PSLM) made of 3-(trihydroxysilyl)propyl methylphosphonate, monosodium salt, as the single silica source, has been obtained from its aqueous solution through a xerogel process and mild thermal aging. The method is simple, affording bulk quantities of powdered PSLM in a single-step. The hybrid is stable in water and possesses a high content of phosphonate groups fixed on the solid matrix. In addition, PSLM shows good thermal stability, which exceeds 300 °C in air. The material was characterized using SEM, TEM, XRD, FT-IR and TGA techniques. Potentiometric titrations show that PSLM bears high-surface density of phosphonate groups (3 mmol g{sup ?1}). As a result, the material displays high metal uptake capacity for heavy metal ions such as Cu{sup 2+} (2.72 mmol g{sup ?1}), Pb{sup 2+} (1.67 mmol g{sup ?1}) and Cd{sup 2+} (1.00 mmol g{sup ?1}) at neutral pH values e.g. the pH of natural waters. Detailed theoretical modeling using a Surface Complexation Model combined with Electron Paramagnetic Resonance (EPR) spectroscopy shows that the surface distribution of surface bound Cu{sup 2+} ions is rather homogeneous e.g. copper-binding phosphonate sites are arranged in average distances 5–8 ?.

  16. Study of surfaces and surface layers on high temperature materials after short-time thermal loads

    International Nuclear Information System (INIS)

    Being part of the plasma-wall interaction during TOKAMAK operation, erosion- and redeposition processes of First Wall materials substantially influence plasma parameters as well as the properties of the First Wall. An important redeposition process of eroded material is the formation of thin films by atomic condensation. Examinations of First Wall components after TOKAMAK operation lead to the assumption that these thin metallic films tend to agglomerate to small particles under subsequent heat load. In laboratory experiments it is shown that thin metallic films on various substrates can agglomerate under short time high heat fluxes and also under longer lasting lower thermal loads, thus verifying the ''agglomeration hypothesis''. (orig.)

  17. Determining the humidity profiles in thick layers of building materials by means of prompt gamma neutron activation analysis

    International Nuclear Information System (INIS)

    A new non-destructive and quantitative test method for determining the humidity profiles of thick layers (0.2-0.8 m) of building materials and structures is proposed. The method is based on spectrometric detection of hard prompt gamma rays (2.23 MeV) from the absorption of thermalised fast neutrons in hydrogen nuclei. For scanning the object, e.g.: A thick layer made of concrete or bricks etc. in the X, Y direction, one uses a collimated bundle of fast neutrons (14 MeV) from a mobile neutron generator. The humidity profile is determined by gamma spectrometer scanning of the prompt gamma source density along the optical path of the neutron bundle in the object, by means of a gas spectrometer equipped with a collimator (ID tomography). The method makes the simultaneous detection of different nests of salts and structural materials, e.g. steel bars, copper or aluminium plates, possible. Based on the transport properties of the neutrons and the properties of the PGNAA method, the characteristic properties and experimental possibilities of the proposed method are described. The plans for researching and developing the method and the adaptation of the measuring apparatus are explained. (orig./HP)

  18. Phenylvinyl-Substituted Carbazole Twin Compounds as Efficient Materials for the Charge-Transporting Layers of OLED Devices

    Science.gov (United States)

    Tavgeniene, D.; Liu, L.; Krucaite, G.; Volyniuk, D.; Grazulevicius, J. V.; Xie, Z.; Zhang, B.; Grigalevicius, S.

    2015-10-01

    Twin compounds containing two phenylvinyl-substituted carbazole rings were synthesized by multi-step synthesis. The compounds were characterized by thermogravimetric analysis, differential scanning calorimetry, and electron photoemission spectroscopy. The thermal stability of the materials was very high; initial thermal degradation temperatures were in the range 411-419°C. The glass-transition temperatures of the amorphous materials were in the range 74-119°C. Electron photoemission spectra of thin layers of the compounds revealed ionization potentials were in the range 5.05-5.45 eV. The hole-transporting properties of thin amorphous layers of the twin compounds were tested in organic light-emitting diodes with Alq3 as green emitter. The best overall performance was observed for a device based on the twin compound containing 3-[2-(4-methylphenyl)vinyl]carbazole groups; the turn-on voltage was 2.6 V, the maximum photometric efficiency 2.34 cd/A, and maximum brightness approximately 7380 cd/m2. At a brightness of 1000 cd/m2 the photometric efficiency was 23% higher than for a PEDOT:PSS-based device.

  19. A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Makoto, E-mail: waseda.ogawa@gmail.com [Graduate School of Creative Science and Engineering, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan); Department of Earth Sciences, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan); Morita, Masashi, E-mail: m-masashi@y.akane.waseda.jp [Graduate School of Creative Science and Engineering, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan); Igarashi, Shota, E-mail: uxei_yoshi_yoshi@yahoo.co.jp [Graduate School of Creative Science and Engineering, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan); Sato, Soh, E-mail: rookie_so_sleepy@yahoo.co.jp [Graduate School of Creative Science and Engineering, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan)

    2013-10-15

    A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 µm was prepared to show the effects of the particle size on the materials performance. The potassium lithium titanate was prepared by solid-state reaction as reported previously, where the reaction temperature was varied. The reported temperature for the titanate preparation was higher than 800 °C, though 600 °C is good enough to obtain single-phase potassium lithium titanate. The lower temperature synthesis is cost effective and the product exhibit better performance as photocatalysts due to surface reactivity. - Graphical abstract: Finite particle of a layered titanate, potassium lithium titanate, was prepared by solid-state reaction at lower temperature to show modified materials performance. Display Omitted - Highlights: • Potassium lithium titanate was prepared by solid-state reaction. • Lower temperature reaction resulted in smaller sized particles of titanate. • 600 °C was good enough to obtain single phased potassium lithium titanate. • The product exhibited better performance as photocatalyst.

  20. Imaging of phase change materials below a capping layer using correlative infrared near-field microscopy and electron microscopy

    Science.gov (United States)

    Lewin, M.; Hauer, B.; Bornhöfft, M.; Jung, L.; Benke, J.; Michel, A.-K. U.; Mayer, J.; Wuttig, M.; Taubner, T.

    2015-10-01

    Phase Change Materials (PCM) show two stable states in the solid phase with significantly different optical and electronic properties. They can be switched reversibly between those two states and are promising candidates for future non-volatile memory applications. The development of phase change devices demands characterization tools, yielding information about the switching process at high spatial resolution. Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) allows for spectroscopic analyses of the different optical properties of the PCMs on the nm-scale. By correlating the optical s-SNOM images with transmission electron microscopy images of the same sample, we unambiguously demonstrate the correlation of the infrared optical contrast with the structural state of the phase change material. The investigated sample consists of sandwiched amorphous and crystalline regions of Ag 4 In 3 Sb 67 Te 26 below a 100 nm thick ( ZnS ) 80 - ( SiO2 ) 20 capping layer. Our results demonstrate the sensitivity of s-SNOM to small dielectric near-field contrasts even below a comparably thick capping layer ( 100 nm ).

  1. A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance

    International Nuclear Information System (INIS)

    A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 µm was prepared to show the effects of the particle size on the materials performance. The potassium lithium titanate was prepared by solid-state reaction as reported previously, where the reaction temperature was varied. The reported temperature for the titanate preparation was higher than 800 °C, though 600 °C is good enough to obtain single-phase potassium lithium titanate. The lower temperature synthesis is cost effective and the product exhibit better performance as photocatalysts due to surface reactivity. - Graphical abstract: Finite particle of a layered titanate, potassium lithium titanate, was prepared by solid-state reaction at lower temperature to show modified materials performance. Display Omitted - Highlights: • Potassium lithium titanate was prepared by solid-state reaction. • Lower temperature reaction resulted in smaller sized particles of titanate. • 600 °C was good enough to obtain single phased potassium lithium titanate. • The product exhibited better performance as photocatalyst

  2. Measurement method for high-temperature infrared optical constants of ZnS crystal materials in a multi-layer structure

    Science.gov (United States)

    Fu, Tairan; Liu, Jiangfan

    2015-03-01

    An inverse method was used to calculate the optical constants of high-temperature semi-transparent materials in the infrared spectra based on the angle dependent transmittances of multi-layer structure. The radiative transfer model for the multi-layer semi-transparent structure was established. A three-layer structure composed by zinc sulfide (ZnS) infrared optical materials was investigated with a numerical analysis of the radiation characteristics to analyze the effects of the two side layers (defined as optical windows) on the radiation properties of the three-layer structure. The inverse calculations of the optical constants of ZnS materials were carried out based on the total transmittances of the three-layer structure at different incidence angles using the Levenberg-Marquardt algorithm. The inverse accuracy for the optical constants was numerically verified. This research works provides a reference for measurements of high-temperature radiation properties of semi-transparent materials in multi-layer structure.

  3. Features in Energy Accumulation in Double Layer on the surface of Graphene Material

    CERN Document Server

    Kompan, Mikhail Evgenievich; Maslov, Alexander Yurievich; Kuznetsov, Viktor Petrovich; Krivchenko, Viktor Aleksandrovich

    2015-01-01

    An application of quantum size carbon structures--graphenes as electrodes of supercapacitors is studied. A fundamental limit of energy and power density arising from quantum nature of objects due to singularity in graphene density of states near Dirac point is determined and technical solutions to partially offset the negative factors are considered. The maximum possible specific capacitance of nanostructured electrode materials is determined.

  4. Impact of Carbon and Tungsten as Divertor Materials on the Scrape-off Layer Conditions in JET

    International Nuclear Information System (INIS)

    Full text: In detached divertor conditions, a five-fold stronger reduction of the ion current to the low-field side target plate and a 30% increase in the density limit were observed in neutral-beam heated, low-confinement mode plasmas with the ITER-like Wall compared to the previous carbon wall. These significant differences occurred at higher core densities despite the fact that nearly identical scrape-off layer parameters were measured in attached divertor conditions. When attached, the magnitude and distribution of radiative power as well as the total ion currents to the divertor target plates were measured the same for a range of divertor plasma geometries, including configurations with the high field side strike point on the vertical plate and the low field side strike point on the horizontal plate, and configurations with both strike points on the vertical plates. The 5-to-10-fold reduction of the scrape-off layer carbon content as inferred from low charge state carbon emission, and the fact that both beryllium and tungsten have a low radiation potential in the scrape-off layer, would indicate that the deuterium emission was and still is the dominating radiator. Simulations of deuterium gas fuelling scans with the fluid edge code EDGE2/EIRENE show that replacing carbon with beryllium and tungsten as wall materials leads to reduced impurity radiation, as expected, and translates into an increase in the power conducted to the plates. The ion currents to the plates, however, are predicted to be similar in both materials configurations. Saturation of the ion currents is predicted at the highest achievable density; the simulations do not predict the reduction of the currents close to the density limit as observed in the experiments. Since the JET ITER-like wall constitutes the same materials and their poloidal distribution as foreseen for the nuclear phase of ITER, understanding the observed differences in the SOL conditions between the two materials configuration, and clarifying the discrepancy between the experimental data and simulations are instrumental for erosion and power handling in ITER. (author)

  5. Gate-tunable diode and photovoltaic effect in an organic-2D layered material p-n junction

    Science.gov (United States)

    Vélez, Saül; Ciudad, David; Island, Joshua; Buscema, Michele; Txoperena, Oihana; Parui, Subir; Steele, Gary A.; Casanova, Fèlix; van der Zant, Herre S. J.; Castellanos-Gomez, Andres; Hueso, Luis E.

    2015-09-01

    The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 104, while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ~11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications.The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 104, while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ~11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04083c

  6. Controllable synthesis of graphene sheets with different numbers of layers and effect of the number of graphene layers on the specific capacity of anode material in lithium-ion batteries

    International Nuclear Information System (INIS)

    High quality graphene sheets are synthesized through efficient oxidation process followed by rapid thermal expansion and reduction by H2. The number of graphene layers is controlled by tuning the oxidation degree of GOs. The higher the oxidation degree of GOs is getting, the fewer the numbers of graphene layers can be obtained. The material is characterized by elemental analysis, thermo-gravimetric analysis, scanning electron microscopy, atomic force microscopy, transmission electron microscopy and Fourier transform infrared spectroscopies. The obtained graphene sheets with single, triple and quintuplicate layers as anode materials exhibit a high reversible capacity of 1175, 1007, and 842 mA h g-1, respectively, which show that the graphene sheets with fewer layers have higher reversible capacity. -- Graphical abstract: The typical TEM images of the graphene sheets derived from GO3(a), GO2(b) and GO1(c). Display Omitted Highlights: ? With the oxidation degree of GO increasing, the numbers of graphene layers decreased. ? With the numbers of graphene layers decreasing, the reversible capacity improved. ? Graphene sheets with single-layer exhibit the best electrochemical performances.

  7. Sensitivity study of multi-layer active magnetic regenerators using first order magnetocaloric material La(Fe,Mn,Si)13Hy

    DEFF Research Database (Denmark)

    Lei, Tian; Nielsen, Kaspar Kirstein

    2015-01-01

    We present simulation results of multi-layer active magnetic regenerators using the solid-state refrigerant La(Fe,Mn,Si)13Hy. This material presents a large, however quite sharp, isothermal entropy change that requires a careful choice of number of layers and working temperature for multi-layer regenerators. The impact of the number of layers and the sensitivity to the working temperature as well as the temperature span are quantified using a one dimensional numerical model. A study of the sensitivity of variation in Curie temperature through a uniform and normal distribution is also presented. The results show that the nominal cooling power is very sensitive to the Curie temperature variation in the multi-layer regenerators. A standard deviation of the Curie temperature variation for a normal distribution less than 0.6 K is suggested in order to achieve sufficient performance of a 15-layer regenerator with Curie temperature spacing of 2 K.

  8. Sliding friction of thick and thin oxygen layers on spin crossover materials

    Science.gov (United States)

    Fredricks, Zachary B.; Stevens, K. M.; Dougherty, Daniel; Krim, Jacqueline

    2015-03-01

    Friction at the nanoscale is known to encompass phononic, electrostatic, conduction electronic and magnetic effects, with relatively little known about magnetic contributions to friction. To probe such effects we have employed a quartz crystal microbalance technique to record the sliding friction associated with thin and thick films of solid and liquid oxygen, a paramagnetic material, atop nanoscale films of the spin-crossover material Fe[(H2Bpz2)2 bpy], which is diamagnetic at cryogenic temperatures and paramagnetic at room temperature. Previously these systems have been shown to be frictionally sensitive to the application of small fields, for Pb(111) substrates. We observe changes in dissipation as well for Fe[(H2Bpz2)2 bpy], in response to externally applied magnetic fields. We will report our efforts to model the frictional interaction, which is reduced in the presence of a weak applied magnetic field, and is also observed to be temperature dependent. NSF DMR085204.

  9. Layer cathode methods of manufacturing and materials for Li-ion rechargeable batteries

    Science.gov (United States)

    Kang, Sun-Ho (Naperville, IL); Amine, Khalil (Downers Grove, IL)

    2008-01-01

    A positive electrode active material for lithium-ion rechargeable batteries of general formula Li.sub.1+xNi.sub..alpha.Mn.sub..beta.A.sub..gamma.O.sub.2 and further wherein A is Mg, Zn, Al, Co, Ga, B, Zr, or Ti and 0material is manufactured by employing either a solid state reaction method or an aqueous solution method or a sol-gel method which is followed by a rapid quenching from high temperatures into liquid nitrogen or liquid helium.

  10. Development of photocatalytic ceramic materials through the deposition of TiO2 nanoparticles layers

    OpenAIRE

    Carneiro, Joaquim A. O.; Teixeira, Vasco M. P.; Azevedo, Sofia; Fernandes, Filipa; Neves, Jorge

    2012-01-01

    Urbanism and communities centralization enlarges atmospheric pollution that affects both human beings as well as their constructed buildings. Different scientific and technological studies are being conducted, both in academic and construction industry, aiming the development of new construction materials with properties that can decrease visual pollution of cities, reducing also the number of cleanings required. The present research work aims the study and the production of self-cleaning ...

  11. Ballistic impact properties of mixed multi-layered amorphous surface alloyed materials fabricated by high-energy electron-beam irradiation

    International Nuclear Information System (INIS)

    The objective of this study is to investigate ballistic impact properties of multi-layered amorphous surface alloyed materials fabricated by high-energy electron-beam irradiation. The mixture of Zr-based amorphous alloy powders and LiF+MgF2 flux powders was deposited on a Ti alloy substrate, and then electron beam was irradiated on this powder mixture to fabricate an one-layered surface alloyed material. On top of this layer, the powder mixture was deposited again and then irradiated with electron beam whose beam current was decreased to fabricate the multi-layered surface alloyed material. In the mixed multi-layered surface alloyed materials fabricated with LM1 alloy powders and LM2 or LM10 alloy powders, the surface region consisted of amorphous phases, together with a small amount of crystalline particles, whereas the center region was complicatedly composed of amorphous phases, crystallized phases, and dendritic ? phases. Since the surface region mostly composed of amorphous matrix was quite hard, the alloyed materials sufficiently blocked the travel of a projectile. When cracks formed at the surface region propagated into the center region, the formation of many cracks or debris was accelerated, which could beneficially work for absorbing the ballistic impact energy, thereby leading to the higher ballistic impact properties than the surface alloyed materials fabricated with LM1 or LM2 alloy powders

  12. Ballistic impact properties of mixed multi-layered amorphous surface alloyed materials fabricated by high-energy electron-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Do, Jeonghyeon [High Temperature Materials Group, Korea Institute of Materials Science, Changwon 642-832 (Korea, Republic of); Jeon, Changwoo [Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Song, Young Buem [Agency for Defense Development, Daejeon 300-600 (Korea, Republic of); Lee, Sunghak, E-mail: shlee@postech.ac.kr [Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-03-01

    The objective of this study is to investigate ballistic impact properties of multi-layered amorphous surface alloyed materials fabricated by high-energy electron-beam irradiation. The mixture of Zr-based amorphous alloy powders and LiF+MgF{sub 2} flux powders was deposited on a Ti alloy substrate, and then electron beam was irradiated on this powder mixture to fabricate an one-layered surface alloyed material. On top of this layer, the powder mixture was deposited again and then irradiated with electron beam whose beam current was decreased to fabricate the multi-layered surface alloyed material. In the mixed multi-layered surface alloyed materials fabricated with LM1 alloy powders and LM2 or LM10 alloy powders, the surface region consisted of amorphous phases, together with a small amount of crystalline particles, whereas the center region was complicatedly composed of amorphous phases, crystallized phases, and dendritic ? phases. Since the surface region mostly composed of amorphous matrix was quite hard, the alloyed materials sufficiently blocked the travel of a projectile. When cracks formed at the surface region propagated into the center region, the formation of many cracks or debris was accelerated, which could beneficially work for absorbing the ballistic impact energy, thereby leading to the higher ballistic impact properties than the surface alloyed materials fabricated with LM1 or LM2 alloy powders.

  13. Positron annihilation lifetime spectroscopy (PALS) application in metal barrier layer integrity for porous low- k materials

    CERN Document Server

    Simon, Lin; Gidley, D W; Wetzel, J T; Monnig, K A; Ryan, E T; Simon, Jang; Douglas, Yu; Liang, M S; En, W G; Jones, E C; Sturm, J C; Chan, M J; Tiwari, S C; Hirose, M

    2002-01-01

    Positron Annihilation Lifetime Spectroscopy (PALS) is a useful tool to pre-screen metal barrier integrity for Si-based porous low-k dielectrics. Pore size of low-k, thickness of metal barrier Ta, positronium (Ps) leakage from PALS, trench sidewall morphology, electrical test from one level metal (1LM) pattern wafer and Cu diffusion analysis were all correlated. Macro-porous low-k (pore size >=200 AA) and large scale meso-porous low-k (>50~200 AA) encounter both Ps leakage and Cu diffusion into low-k dielectric in the 0.25 mu mL/0.3 mu mS structures when using SEMATECH in-house PVD Ta 250 AA as barrier layer. For small scale meso-porous (>20~50 AA) and micro- porous (<=20 AA) low-k, no Ps leakage and no Cu diffusion into low-k were observed even with PVD Ta 50 AA, which is proved also owing to sidewall densification to seal all sidewall pores due to plasma etch and ash. For future technology, smaller pore size of porous Si-based low-k (=<50 AA) will be preferential for dense low-k like trench sidewall to...

  14. Investigation into the manufacturing of female blanking dies made of multi-layers of steel and superplastic Materials

    International Nuclear Information System (INIS)

    Superplasticity is a feature which means the ability of deforming up to large strains at relatively low stresses when the material is deformed under certain condition of temperature and strain rate. This superplastic characteristic of metals and alloys is invested in manufacturing parts mainly used in the automobile industry. Superplastic tin-lead eutectic alloy is usually used for the laboratory investigations due to its low melting point, high ductility, and very low strength. In this paper, the utilization of superplastic tin-lead alloy is used to investigate the possibility of manufacturing female blanking dies. These dies are mainly machined with loss of materials with time consuming and high cost particularly in case of complicated and intricate shapes of dies. The idea was brought about from a previous work of one of the authors on the blanking of this superplastic materials where the best quality blanks (i.e. minimum dishing, doming and edge taper) of the blanks at zero radial clearance percentage. Hence, the pierced sheet will have the same dimensions and details of the punch. Multi layered plate made of alternative laminates of steel and tin-lead superplastic material joined at their interfaces by an adhesive material of high shear strength, araldite, were used in producing the female dies, by piercing the plate by a punch of the required shape. Three different shapes of blanking dies were produced the details of the punches appeared clearly in the pierced plate. This newly reported method has the following advantages, high accuracy is achieved, low force and energy are required for production of the dies, and hence low production cost. (author)

  15. The properties of thickness-twist (TT) wave modes in a rotated Y-cut quartz plate with a functionally graded material top layer.

    Science.gov (United States)

    Wang, Bin; Qian, Zhenghua; Li, Nian; Sarraf, Hamid

    2016-01-01

    We propose the use of thickness-twist (TT) wave modes of an AT-cut quartz crystal plate resonator for measurement of material parameters, such as stiffness, density and material gradient, of a functionally graded material (FGM) layer on its surface, whose material property varies exponentially in thickness direction. A theoretical analysis of dispersion relations for TT waves is presented using Mindlin's plate theory, with displacement mode shapes plotted, and the existence of face-shear (FS) wave modes discussed. Through numerical examples, the effects of material parameters (stiffness, density and material gradient) on dispersion curves, cutoff frequencies and mode shapes are thoroughly examined, which can act as a theoretical reference for measurements of unknown properties of FGM layer. PMID:26254981

  16. Growth of type II strained layer superlattice, bulk InAs and GaSb materials for minority lifetime characterization

    Science.gov (United States)

    Svensson, S. P.; Donetsky, D.; Wang, D.; Hier, H.; Crowne, F. J.; Belenky, G.

    2011-11-01

    We have examined the growth of strained layer superlattice (SLS) structures for the purpose of characterizing and improving the minority carrier lifetime. Structures with different SL periods but with same absorption wavelength were first studied. Despite a doubling of the number of interfaces per thickness unit, no significant change was seen in the carrier lifetime. This observation points away from the interfaces as the location of lifetime limiting defect centers. To gain further insights into the spatial location of the defect centers, a series of binary InAs and GaSb layers grown with different substrate temperatures, were studied. We found that higher growth temperatures were beneficial for both binaries, although the improvement for GaSb was less than that of InAs. The substrate temperature was also varied in SLS structures and characterized with high-resolution x-ray diffraction. By using the peak width from the SLS zero-order diffraction as a figure of merit, we found a shallow growth window of ?±20° around an optimum temperature of 440 °C. Outside this temperature window the material quality deteriorated very rapidly. Unfortunately, the substrate temperatures that would provide an improvement in the binary lifetimes fall mainly above the SLS growth window, thus limiting this parameter as a means of improving lifetimes in the SLS. A model that qualitatively relates bulk and SLS lifetimes through native defects is proposed and strategies for improving the lifetimes are discussed.

  17. Effect of initial stress on Love waves in a piezoelectric structure carrying a functionally graded material layer.

    Science.gov (United States)

    Qian, Zheng-Hua; Jin, Feng; Lu, Tianjian; Kishimoto, Kikuo; Hirose, Sohichi

    2010-01-01

    The effect of initial stress on the propagation behavior of Love waves in a piezoelectric half-space of polarized ceramics carrying a functionally graded material (FGM) layer is analytically investigated in this paper from the three-dimensional equations of linear piezoelectricity. The analytical solutions are obtained for the dispersion relations of Love wave propagating in this kind of structure with initial stress for both electrical open case and electrical short case, respectively. One numerical example is given to graphically illustrate the effect of initial stress on dispersive curve, phase velocity and electromechanical coupling factor of the Love wave propagation. The results reported here are meaningful for the design of surface acoustic wave (SAW) devices with high performance. PMID:19828172

  18. Development of composite zirconium materials with increased level of properties and protective layers for new generation LWR active core components

    International Nuclear Information System (INIS)

    Methods are investigated to increase operation properties of zirconium items by modifying their structure-phase state: by liquid metal reinforcement by ordered structures, by methods of solid phase alloying by carbon nanostructures, by methods of granular metallurgy; and also by modifying the surface conditions: using dynamic impact of microbodies and applying of fine surface layers (coatings) by electroarc and magnetron sputtering. The investigations have resulted in obtaining several versions of composite materials based on Russian industrial zirconium alloys having an increased level of properties. The processes have been developed to modify surface and to make protective coatings on the surface of zirconium items. The developed modification methods can be used to increase operation properties and prolong service life of zirconium components of new generation LWR active cores. (author)

  19. Flaw detection in a multi-material multi-layered composite: using fem and air-coupled ut

    International Nuclear Information System (INIS)

    Ceramic tiles are the main ingredient of a multi-layer multi-material composite being considered for the modernization of tank armors. The high stiffness, low attenuation, and precise dimensions of these uniform tiles make them remarkable resonators when driven to vibrate. This study is aimed at modeling the vibration modes of the tiles and the composite lay-up with finite element analysis and comparing the results with the resonance modes observed in air-coupled ultrasonic excitation of the tiles and armor samples. Defects in the tile, during manufacturing and/or after usage, are expected to change the resonance modes. The comparison of a pristine tile/lay-up and a defective tile/lay-up will thus be a quantitative damage metric. The understanding of the vibration behavior of the tile, both by itself and in the composite lay-up, can provide useful guidance to the nondestructive evaluation of armor panels containing ceramic tiles.

  20. Flaw Detection in a Multi-Material Multi-Layered Composite: Using FEM and Air-Coupled UT

    Science.gov (United States)

    Livings, R. A.; Dayal, V.; Barnard, D. J.; Hsu, D. K.

    2011-06-01

    Ceramic tiles are the main ingredient of a multi-layer multi-material composite being considered for the modernization of tank armors. The high stiffness, low attenuation, and precise dimensions of these uniform tiles make them remarkable resonators when driven to vibrate. This study is aimed at modeling the vibration modes of the tiles and the composite lay-up with finite element analysis and comparing the results with the resonance modes observed in air-coupled ultrasonic excitation of the tiles and armor samples. Defects in the tile, during manufacturing and/or after usage, are expected to change the resonance modes. The comparison of a pristine tile/lay-up and a defective tile/lay-up will thus be a quantitative damage metric. The understanding of the vibration behavior of the tile, both by itself and in the composite lay-up, can provide useful guidance to the nondestructive evaluation of armor panels containing ceramic tiles.

  1. Mechanically stacked 1 nm thick carbon nanosheets: Ultrathin layered materials with tunable optical, chemical and electrical properties

    CERN Document Server

    Nottbohm, Christoph T; Beyer, Andre; Stosch, Rainer; Golzhauser, Armin; 10.1002/smll.201001993

    2011-01-01

    Carbon nanosheets are mechanically stable free-standing two-dimensional materials with a thickness of ~1 nm and well defined physical and chemical properties. They are made by radiation induced cross-linking of aromatic self-assembled monolayers. Here we present a route to the scalable fabrication of multilayer nanosheets with tunable electrical, optical and chemical properties on insulating substrates. Stacks up to five nanosheets with sizes of ~1 cm^2 on oxidized silicon were studied. Their optical characteristics were investigated by visual inspection, optical microscopy, UV/Vis reflection spectroscopy and model calculations. Their chemical composition was studied by X-ray photoelectron spectroscopy. The multilayer samples were then annealed in ultra high vacuum at various temperatures up to 1100 K. A subsequent investigation by Raman, X-ray photoelectron and UV/Vis reflection spectroscopy as well as by electrical four-point probe measurements demonstrates that the layered nanosheets transform into nanocry...

  2. Electrochemical treatment of Orange II dye solution-Use of aluminum sacrificial electrodes and floc characterization

    Energy Technology Data Exchange (ETDEWEB)

    Mollah, M. Yousuf A. [Department of Chemistry, University of Dhaka, Dhaka-1000 (Bangladesh); Gomes, Jewel A.G., E-mail: jewel.gomes@lamar.edu [Dan F. Smith Department of Chemical Engineering, Lamar University, P.O. Box 10053, Beaumont, TX 77710 (United States); Das, Kamol K.; Cocke, David L. [Gill Chair of Chemical Engineering, Lamar University, P.O. Box 10053, Beaumont, TX 77710 (United States)

    2010-02-15

    Electrocoagulation (EC) of Orange II dye in a flow through cell with aluminum as sacrificial electrodes was carried out under varying conditions of dye concentration, current density, flow rate, conductivity, and the initial pH of the solution in order to optimize the operating parameters for maximum benefits. Maximum removal efficiency of 94.5% was obtained at the following conditions: dye concentration = 10 ppm, current density = 160 A/m{sup 2}, initial pH 6.5, conductance = 7.1 mS/cm, flow rate = 350 mL/min, and concentration of added NaCl = 4.0 g/L of dye solution. The EC-floc was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, and powder X-ray diffraction techniques. The removal mechanism has been proposed that is in compliance with the Pourbaix diagram, solubility curve of aluminum oxides/hydroxides, and physico-chemical properties of the EC-floc.

  3. Colloidal processing and CO2 capture performance of sacrificially templated zeolite monoliths

    International Nuclear Information System (INIS)

    Highlights: ? We demonstrate structuring of hierarchically porous zeolite monoliths. ? Structured zeolite monoliths show high CO2 adsorption capacity. ? Addition of 5 wt% of kaolin to zeolite monoliths ensures a mechanical stability. ? Cyclic adsorption and regeneration show that structured monoliths are robust. -- Abstract: Sacrificial templating of suspension cast and subsequently thermally treated zeolite monoliths with glassy carbon spheres and fibers yielded zeolite 13X and silicalite-1 monoliths with macroporosities up to 50 vol%. Homogeneous distribution of the macroporosity in hierarchically porous monoliths was obtained by tailoring the surface chemistry of the carbon particles by polyelectrolyte-assisted adsorption of zeolite particles. The effect of amount of kaolin binder and temperature for the thermal treatment on the monoliths strength, surface area and CO2 uptake was studied by diametral compression tests, electron microscopy, X-ray diffraction and gas adsorption. Cyclic adsorption and regeneration measurements showed that zeolite 13X monoliths display a high CO2 uptake while the silicalite-1 monoliths could be regenerated with a relatively low energy penalty.

  4. Synthesis of porous silica hollow spheres using sacrificial template for drug delivery applications

    Directory of Open Access Journals (Sweden)

    Rasoul Safdari

    2014-06-01

    Full Text Available In this work, we report on the synthesis of SiO2 hollow spheres using carbon nanospheres as the sacrificial template by hydrothermal method. The synthesized substrates are in a spherical morphology and uniform size distribution. The effects of hydrothermal process, concentration and the reaction temperature were optimized during synthesis of carbon nanospheres. Infrared spectroscopy (IR, and scanning electronic microscopy (SEM methods were used for identification of the synthesized products. The synthesized SiO2 nanospheres were used as drug carrier to investigate in vitro release behavior of monoterpenic phenol isomers, carvacrol and thymol, in simulated body fluid (SBF. Ultraviolet-visible spectroscopy (UV-vis method was carried out to determine the amount of the drugs entrapped in the carrier. The results indicated that SiO2 nanospheres have high ability to adsorb the drugs and there is no need for adjusting the pH during the adsorption process. The drug release profile shows a three stages pattern and indicates a delayed release action.

  5. Long-term performance of different aluminum alloy designs as sacrificial anodes for rebars

    Directory of Open Access Journals (Sweden)

    de Rincón, O.

    2003-12-01

    Full Text Available This paper presents the performance of various cathodic-protection designs using Aluminum alloys to protect prestressed piles. The results obtained with different system designs (bracelete type-Al/Zn/In alloy, thermosprayed aluminum (3-year evaluation and conventional Al/Zn/In anocies in an epoxy-painted steel bracelet (12-year evaluation, indicated that all of these systems may be used as sacrificial anodes for pile protection. However, the thermosprayed aluminum type can not be used in prestressed concrete piles because the very negative potentials ( < -1100 mV vs. Cu/CuSO4 they supply to the reinforcement could lead to hydrogen embrittlement.

    Este trabajo presenta la realización de varios diseños de protección catódica utilizando aleaciones de aluminio para la protección de pilotes pretensados. Los resultados obtenidos con diferentes diseños (aleación de Al/Zn/In, tipo brazalete y aluminio termorociado (3 años de evaluación y ánodos convencionales de Al/Zn/In colocados en un brazalete de acero pintado con epoxy (12 años de evaluación, indicaron que todos estos sistemas pueden ser utilizados como ánodos de sacrificio para la protección de los pilotes. Sin embargo, el sistema con aluminio termorociado no puede ser utilizado en pilotes de acero pretensado debido al potencial muy negativo alcanzado por la armadura (<-1100 mV vs Cu/CuSO4, lo cual podría inducir a daños por hidrógeno.

  6. Properties of the material spontaneously formed in interfacial layer of system at extraction of rare-earth elements

    Science.gov (United States)

    Kizim, N. F.; Golubina, E. N.; Chekmarev, A. M.

    2013-03-01

    The wetting ability of the material formed spontaneously in the interface layer of an aqueous solution of a rare-earth element (REE) salt/solution of di-(2-ethylhexyl)phosphoric acid (D2EHPA) extraction system adhered onto a glass plate is investigated. It is found that its properties depend on the natures of the REE and the solvent, and the initial concentrations of the REE and the extracting reactant. It is shown that the material formed at the interface and adhered onto a glass plate has controlled wetting ability. The difference between the properties of interface REE formations for yttrium and cerium subgroups is established. The electric conductivity of interphase formations in the same systems is measured and shown to display an extreme dependence on time in systems with heptane but a monotonically increasing one in systems with toluene. It is shown that the electric conductivity of interphase formations diminishes sharply with an increase in the ratio of the initial concentrations of REE salt and D2EHPA. It is concluded that an increase in the relative gain of the average molar mass of interphase formations indicates coagulation and the formation of polymers.

  7. Development of a helium-cooled divertor: Material choice and technological studies

    International Nuclear Information System (INIS)

    Within the framework of the EU power plant conceptual study (PPCS), a He-cooled divertor concept has been investigated at Forschungszentrum Karlsruhe in cooperation with the Efremov Institute. The design goal is to remove a high heat load of at least 10 MW/m2. The design is based on a modular construction of cooling finger unit that helps reduce thermal stresses. The divertor finger unit, which is cooled by high pressure helium, consists of a tungsten tile as thermal shield and sacrificial layer, and a thimble made of tungsten alloy. The success of this design depends strongly on the effectiveness of the cooling technology and on the availability of appropriate structural materials such as tungsten alloy and oxide-dispersion-strengthened (ODS) steel as well as the related fabrication and joining technology. Results of this investigation are discussed in the paper

  8. Effect of Capping Front Layer Materials on the Penetration Resistance of Q&T Steel Welded Joints Against 7.62-mm Armor-Piercing Projectile

    Science.gov (United States)

    Balakrishnan, M.; Balasubramanian, V.; Madhusudhan Reddy, G.; Parameswaran, P.

    2013-09-01

    In the present investigation, an attempt has been made to study the effect of capping front layers on the ballistic performance of shielded metal arc-welded armor steel joints which were fabricated with a chromium carbide-rich hardfaced middle layer on the buttered/beveled edge. Two different capping front layer materials were chosen for achieving better ballistic performance, namely, low hydrogen ferritic (LHF) and austenitic stainless steel (SS) fillers. On the other hand, the bottom layers are welded with SS filler for both joints. The consequent sandwiched joint served the dual purpose of weld integrity and penetration resistance of the bullet. It is observed that the penetration resistance is due to the high hardness of the hardfacing layer on the one hand and the energy-absorbing capacity of the soft backing SS weld deposits on the other hand. The complementary effect of layers successfully provided resistance to the projectile penetration. On a comparative analysis, the joint fabricated using the LHF filler capping front layer offered superior ballistic performance with respect to depth of penetration. This is mainly due to the presence of acicular ferrite along the bainitic structure in the LHF capping front layer, which caused a shallow hardness gradient along the weld center line.

  9. Highly Dispersed Ultrafine Pt Nanoparticles on Reduced Graphene Oxide Nanosheets: In Situ Sacrificial Template Synthesis and Superior Electrocatalytic Performance for Methanol Oxidation.

    Science.gov (United States)

    Wu, Shouliang; Liu, Jun; Tian, Zhenfei; Cai, Yunyu; Ye, Yixing; Yuan, Qinglin; Liang, Changhao

    2015-10-21

    We report a simple and environmentally friendly route to prepare platinum/reduced graphene oxide (Pt/rGO) nanocomposites (NCs) with highly reactive MnOx colloids as reducing agents and sacrificial templates. The colloids are obtained by laser ablation of a metallic Mn target in graphene oxide (GO)-containing solution. Structural and morphological investigations of the as-prepared NCs revealed that ultrafine Pt nanoparticles (NPs) with an average size of 1.8 (±0.6) nm are uniformly dispersed on the surfaces of rGO nanosheets. Compared with commercial Pt/C catalysts, Pt/rGO NCs with highly electrochemically active surface areas show remarkably improved catalytic activity and durability toward methanol oxidation. All of these superior characteristics can be attributed to the small particle size and uniform distribution of the Pt NPs, as well as the excellent electrical conductivity and stability of the rGO catalyst support. These findings suggest that Pt/rGO electrocatalysts are promising candidate materials for practical use in fuel cells. PMID:26435201

  10. Atomic-Resolution Visualization of Distinctive Chemical Mixing Behavior of Ni, Co and Mn with Li in Layered Lithium Transition-Metal Oxide Cathode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Pengfei; Zheng, Jianming; Lv, Dongping; Wei, Yi; Zheng, Jiaxin; Wang, Zhiguo; Kuppan, Saravanan; Yu, Jianguo; Luo, Langli; Edwards, Danny J.; Olszta, Matthew J.; Amine, Khalil; Liu, Jun; Xiao, Jie; Pan, Feng; Chen, Guoying; Zhang, Jiguang; Wang, Chong M.

    2015-07-06

    Capacity and voltage fading of layer structured cathode based on lithium transition metal oxide is closely related to the lattice position and migration behavior of the transition metal ions. However, it is scarcely clear about the behavior of each of these transition metal ions. We report direct atomic resolution visualization of interatomic layer mixing of transition metal (Ni, Co, Mn) and lithium ions in layer structured oxide cathodes for lithium ion batteries. Using chemical imaging with aberration corrected scanning transmission electron microscope (STEM) and DFT calculations, we discovered that in the layered cathodes, Mn and Co tend to reside almost exclusively at the lattice site of transition metal (TM) layer in the structure or little interlayer mixing with Li. In contrast, Ni shows high degree of interlayer mixing with Li. The fraction of Ni ions reside in the Li layer followed a near linear dependence on total Ni concentration before reaching saturation. The observed distinctively different behavior of Ni with respect to Co and Mn provides new insights on both capacity and voltage fade in this class of cathode materials based on lithium and TM oxides, therefore providing scientific basis for selective tailoring of oxide cathode materials for enhanced performance.

  11. Diseño de aleaciones para ánodos de sacrificio sustentables / Designing alloys for sustainable sacrificial anodes

    Scientific Electronic Library Online (English)

    Guillermo, Salas-Banuet; Laura, Verduzco-Flores.

    2013-06-01

    Full Text Available Se presenta: un proceso de diseño de aleaciones para fabricar ánodos de sacrificio, usados en ambientes marinos; la propuesta de sustituir al In con Ag, en aleaciones Al-Zn-In, buscando sustentar el medio ambiente; y la proposición de incluir los parámetros de los procesos de fabricación de ánodos y [...] los estructurales en la normatividad sobre ánodos de sacrificio. Se manufacturaron en el laboratorio, se ensayaron y compararon ocho aleaciones Al-Zn 2% (contenido menor al que señala la norma para aleaciones con In (de 3.5 a 5%) y con Sn (de 4 a 5%), buscando mayor sustentabilidad); cuatro se alearon con In (de 0.59 a 0.766%) y cuatro con Ag (de 0.23 a 0.428%). Se usaron dos rapideces de enfriamiento durante la solidificación, buscando modificar la estructura y cambiar propiedades y comportamientos ante la corrosión -el potencial de corrosión, la rapidez de corrosión, la activación del ánodo, el tipo de corrosión y la eficiencia de corriente-. se evaluaron las estructuras y se midieron sus potenciales; se encontró que la variación de la rapidez de enfriamiento modificó la estructura de las aleaciones, sus propiedades y comportamientos ante la corrosión y que el comportamiento general de algunas de las aleaciones con Ag es superior a las que contienen in. Las mayores eficiencias se dieron en las aleaciones con menor contenido de In (69%) y de Ag (71%). Abstract in english In this paper we present: a) a design process for manufacturing alloys to be used as sacrificial anodes in marine environments; b) the proposal to replace in with Ag, in search of alloys that could contribute to environmental sustain; and c) the proposal to include the parameters related to anode st [...] ructure and their manufacturing process in the regulation of sacrificial anodes. Eight Al-Zn 2% alloys were manufactured, tested, and compared in our laboratory. These had a lower content than the one indicated by the alloy standards - 3.5-5% and 4-5% content for in and Sn respectively- looking for a more sustainable environment. Four of them were alloyed with In (from 0.59 to 0.766%), and four with Ag (from 0.23 to 0.428%). in order to modify the structure, two cooling rates were used during solidification, seeking to modify their properties, and hence their behavior against corrosion, i.e. corrosion potential, corrosion rate, anode activation, type of corrosion and current efficiency. It was found that the variation of the cooling rate changes the structure of the alloys, their properties and corrosion behaviors. The overall behavior of some of the Ag alloys is superior to those containing In. The higher efficiencies were obtained for alloys with the lower amount of In (69%) and Ag (71%).

  12. Sodium montmorillonite/amine-containing drugs complexes: new insights on intercalated drugs arrangement into layered carrier material.

    Science.gov (United States)

    Bello, Murilo L; Junior, Aridio M; Vieira, Bárbara A; Dias, Luiza R S; de Sousa, Valéria P; Castro, Helena C; Rodrigues, Carlos R; Cabral, Lucio M

    2015-01-01

    Layered drug delivery carriers are current targets of nanotechnology studies since they are able to accommodate pharmacologically active substances and are effective at modulating drug release. Sodium montmorillonite (Na-MMT) is a clay that has suitable properties for developing new pharmaceutical materials due to its high degree of surface area and high capacity for cation exchange. Therefore Na-MMT is a versatile material for the preparation of new drug delivery systems, especially for slow release of protonable drugs. Herein, we describe the intercalation of several amine-containing drugs with Na-MMT so we can derive a better understanding of how these drugs molecules interact with and distribute throughout the Na-MMT interlayer space. Therefore, for this purpose nine sodium montmorillonite/amine-containing drugs complexes (Na-MMT/drug) were prepared and characterized. In addition, the physicochemical properties of the drugs molecules in combination with different experimental conditions were assessed to determine how these factors influenced experimental outcomes (e.g. increase of the interlayer spacing versus drugs arrangement and orientation). We also performed a molecular modeling study of these amine-containing drugs associated with different Na-MMT/drug complex models to analyze the orientation and arrangement of the drugs molecules in the complexes studied. Six amine-containing drugs (rivastigmine, doxazosin, 5-fluorouracil, chlorhexidine, dapsone, nystatin) were found to successfully intercalate Na-MMT. These findings provide important insights on the interlayer aspect of the molecular systems formed and may contribute to produce more efficient drug delivery nanosystems. PMID:25803292

  13. Sodium Montmorillonite/Amine-Containing Drugs Complexes: New Insights on Intercalated Drugs Arrangement into Layered Carrier Material

    Science.gov (United States)

    Vieira, Bárbara A.; Dias, Luiza R. S.; de Sousa, Valéria P.; Castro, Helena C.; Rodrigues, Carlos R.; Cabral, Lucio M.

    2015-01-01

    Layered drug delivery carriers are current targets of nanotechnology studies since they are able to accommodate pharmacologically active substances and are effective at modulating drug release. Sodium montmorillonite (Na-MMT) is a clay that has suitable properties for developing new pharmaceutical materials due to its high degree of surface area and high capacity for cation exchange. Therefore Na-MMT is a versatile material for the preparation of new drug delivery systems, especially for slow release of protonable drugs. Herein, we describe the intercalation of several amine-containing drugs with Na-MMT so we can derive a better understanding of how these drugs molecules interact with and distribute throughout the Na-MMT interlayer space. Therefore, for this purpose nine sodium montmorillonite/amine-containing drugs complexes (Na-MMT/drug) were prepared and characterized. In addition, the physicochemical properties of the drugs molecules in combination with different experimental conditions were assessed to determine how these factors influenced experimental outcomes (e.g. increase of the interlayer spacing versus drugs arrangement and orientation). We also performed a molecular modeling study of these amine-containing drugs associated with different Na-MMT/drug complex models to analyze the orientation and arrangement of the drugs molecules in the complexes studied. Six amine-containing drugs (rivastigmine, doxazosin, 5-fluorouracil, chlorhexidine, dapsone, nystatin) were found to successfully intercalate Na-MMT. These findings provide important insights on the interlayer aspect of the molecular systems formed and may contribute to produce more efficient drug delivery nanosystems. PMID:25803292

  14. Influence of positive active material type and grid alloy on corrosion layer structure and composition in the valve regulated lead/acid battery

    Science.gov (United States)

    Ball, R. J.; Kurian, R.; Evans, R.; Stevens, R.

    Performance of a valve regulated lead/acid battery is affected by the properties of the positive grid corrosion layer. An investigation has been carried out using a range of experimental techniques to study the influence of corrosion layer composition and structure on cyclic performance. A number of designs of battery were manufactured with different grids and positive active materials (PAMs). Two grid types were used consisting of either pure lead or a lead/tin alloy. Variations in PAM composition and structure were obtained by forming electrodes from grey oxide pastes containing additions of, red lead, tetrabasic lead sulphate, or sulphuric acid (sulphated). Results indicated that both grid alloy composition and PAM type affect the corrosion layer properties. Ultra-microtoming was used to prepare sections of the grid/corrosion layer interface. Results showed that corrosion propagated along tin rich grain boundaries.

  15. Design and performance of a cryogenic scanning tunneling microscope in high magnetic field for 2D layered materials study

    Science.gov (United States)

    Chuang, Tien-Ming; Chung, Pei-Fang; Guan, Syu-You; Yu, Shan-An; Liu, Che-An; Hsu, Chia-Sheng; Su, Chih-Chuan; Sankar, Raman; Chou, Fang-Cheng

    2015-03-01

    We will describe the design and performance of a cryogenic scanning tunneling microscope (STM) system in a high magnetic field. A Pan-type STM is mounted on a homemade low vibration 4He pot refrigerator, which can be operated in continuous flow mode at T ~ 1.6K and in a magnetic field of up to 9 Tesla. A cleavage device at T =4.2K stage is used to cleave the 2D layered materials before inserting into STM as well as functioning as the radiation shield. The liquid helium boil rate of 4.6 liters per day is achieved due to our careful design, which allows the measurement at base temperature up to 10 days. We will demonstrate its capability of measuring atomically registered energy resolved spectroscopic maps in both real space and momentum space by our recent results on Rashba BiTeI. This work is supported by Ministry of Science and Technology, Taiwan and Kenda Foundation, Taiwan.

  16. Theory of the axi-symmetric extrusion process of multi-layer materials with a strong plastic nonhomogeneity

    Directory of Open Access Journals (Sweden)

    J. Piwnik

    2008-03-01

    Full Text Available A novel simplified r hcorctical solution is found lor thc strcss starcs accompanying thc proccss of cxt ri~siono f ma![ i-laycr matcrialsunder rhc conditions af axial symmetry. Thc solution i~ bawd nn ~ h mc n dcl of pcrfcct plastic material satisfying thc Trcsca yicld condition.thc Haar-Karman conditions bcing sntisficd in each layer. Thc laycrs arc chnnctcrizcd by difrercnt yicld limits and stmng plasticnonhomogeneity. In thc ncighhoi~rhoorol f thc interfaces conrinuous variation of rhc yicld limit i s a~sunicdZ. hc form of thc plastic zonc nndpsitions or the contact surfi~ccss eparating rhc laycrs nrc assumcd. Shcaring strcsscs and mcan prcssurc in a longitudinal scclion o f t hccxrruded rod arc cxprcsscd in tcrms of filnctions of the axial coordinatc z. Unknown fttnctions of thc singlc coordinatc z arc dctcrmincdFrom thc yicld conditions writtcn for thc contour of thc die. Accitratc analytical relations arc dcrivcd For tllc normal strcss distribution atthc surface of contact bctwccn thc dic and thc matcrial cxlrudcd, Using thc known normal and shcar stress dislrihutions (due to Iriclion,accuratc valuc of thc lower cstimate of thc cxtrusion forcc is dctcrrnincd. Thc sotution may hc applicd lo ~ h cca scs of arbitrary numhcr oflaycrs and arbitrary h rm oithc dic. I t may bc used to a rational analysis o f ~ h pcro ccss of cxirnsiol~o f multi-lnycr cylindrical rods.

  17. Photochemical generation of strong one-electron reductants via light-induced electron transfer with reversible donors followed by cross reaction with sacrificial donors.

    Science.gov (United States)

    Shan, Bing; Schmehl, Russell

    2014-11-13

    This work illustrates a modified approach for employing photoinduced electron transfer reactions coupled to secondary irreversible electron transfer processes for the generation of strongly reducing equivalents in solution. Through irradiation of [Ru(LL)3](2+) (LL= diimine ligands) with tritolylamine (TTA) as quencher and various alkyl amines as sacrificial electron donors, yields in excess of 50% can be achieved for generation of reductants with E(0)(2+/1+) values between -1.0 and -1.2 V vs NHE. The key to the system is the fact that the TTA cation radical, formed in high yield in reaction with the photoexcited [Ru(LL)3](2+) complex, reacts irreversibly with various sacrificial electron donating amines that are kinetically unable to directly react with the photoexcited complex. The electron transfer between the TTA(+) and the sacrificial amine is an energetically uphill process. Kinetic analysis of these parallel competing reactions, consisting of bimolecular and pseudo first-order reactions, allows determination of electron transfer rate constants for the cross electron transfer reaction between the sacrificial donor and the TTA(+). A variety of amines were examined as potential sacrificial electron donors, and it was found that tertiary 1,2-diamines are most efficient among these amines for trapping the intermediate TTA(+). This electron-donating combination is capable of supplying a persistent reducing flux of electrons to catalysts used for hydrogen production. PMID:24882233

  18. The effect of doping (Mn,B)3O4 materials as protective layers in different metallic interconnects for Solid Oxide Fuel Cells

    Science.gov (United States)

    Miguel-Pérez, Verónica; Martínez-Amesti, Ana; Nó, María Luisa; Larrañaga, Aitor; Arriortua, María Isabel

    2013-12-01

    Spinel oxides with the general formula of (Mn,B)3O4 (B = Co, Fe) were used as barrier materials between the cathode and the metallic interconnect to reduce the rate of cathode degradation by Cr poisoning. The effect of doping at the B position was investigated terms of microstructure and electrical conductivity to determine its behaviour and effectiveness as a protective layer in contact with three metallic materials (Crofer 22 APU, SS430 and Conicro 4023 W 188). The analysis showed that the use of these materials considerably decreased the reactivity and diffusion of Cr between the cathode and the metallic interconnects. The protective layer doped with Fe at the B position exhibited the least amount of reactivity with the interconnector and cathode materials. The worst results were observed for SS430 cells coated with a protective layer perhaps due to their low Cr content. The Crofer 22 APU and Conicro 4023 W 188 samples exhibited very similar conductivity results in the presence of the MnCo1.9Fe0.1O4 protective coating. As a result, these two material combinations are a promising option for use as bipolar plates in SOFC.

  19. Do Jihadist “Martyrs” really want to die? An emic approach to self-sacrificial radicalization in Pakistan

    OpenAIRE

    Blom, Amélie

    2011-01-01

    Using a prosopography based on sources which cannot be verified, most academic works on the phenomenon of suicide bombings tend to present a ‘martyr’ who is hyper-motivated to die. This contrasts with the life stories of former recruits from a Pakistani jihadi militia, which show that individual motivations might be less of a puzzle than the social mechanisms of self-sacrificial radicalization. Three types of mechanisms can then be identified: the fuite en avant, the ‘side-bet’ and the desire...

  20. Simultaneous control of thermoelectric properties in p-type and n-type materials by electric double-layer gating : New design for thermoelectric device

    OpenAIRE

    Takayanagi, Ryohei; Fujii, Takenori; Asamitsu, Atsushi

    2015-01-01

    We report novel design for thermoelectric device which can control thermoelectric properties of p-type and n-type materials simultaneously by electric double-layer gating. Here, p-type Cu2O and n-type ZnO were used as positive and negative electrodes of the electric double-layer capacitor structure. When the gate voltage was applied between two electrodes, the holes and electrons were accumulated on the surface of Cu2O and ZnO, respectively. The thermopower was measured by a...

  1. Visible-light hydrogen generation using as photocatalysts layered titanates incorporating in the intergallery space ruthenium tris(bipyridyl) and methyl viologen.

    Science.gov (United States)

    Sastre, Francesc; Bouizi, Younes; Fornés, Vicente; Garcia, Hermenegildo

    2010-06-01

    A series of layered titanates containing in the interlayer space tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] or methyl viologen (MV(2+)) or both has been prepared and characterized by elemental analyses, XRD, and optical and vibrational spectroscopy. Incorporation of Ru(bpy)(3)(2+) and MV(2+) is confirmed by the increase of the distance between the titanate layers. The presence of Ru(bpy)(3)(2+) in the material is also revealed in optical spectroscopy where the ligand to metal charge transfer band appearing at ?(max) 460 nm is observed. Also incorporation of MV(2+) leads to the observation of the charge transfer complex band with the titanate host from 350 to 650 nm. These solids are active for the photocatalytic hydrogen generation from water when colloidal platinum as catalyst and EDTA as sacrificial electron donor are present in the solution. The maximum efficiency was obtained for a solid consisting of layered titanate containing a 10.2 wt.% loading of Ru(bpy)(3)(2+) incorporated in the titanate layers and MV(2+) and Pt nanoparticles in the aqueous solution. This heterogeneous system produced about one-half the hydrogen generated for the conventional homogeneous system where all the components [Ru(bpy)(3)(2+), MV(2+), Pt, and EDTA] are in solution, with the advantage that it can be used as film or recovered by filtration from the aqueous medium. PMID:20356602

  2. Flaw detection in multi-layer, multi-material composites by resonance imaging: Utilizing Air-coupled Ultrasonics and Finite Element Modeling

    Science.gov (United States)

    Livings, Richard Andrew

    2011-12-01

    Ceramic tiles are the main ingredient of a multi-material, multi-layered composite being considered for the modernization of tank armors. The high stiffness, low attenuation, and precise dimensions of these uniform tiles make them remarkable resonators when driven to vibrate. Defects in the tile, during manufacture or after usage, are expected to change the resonance frequencies and resonance images of the tile. The comparison of the resonance frequencies and resonance images of a pristine tile/lay-up to a defective tile/lay-up will thus be a quantitative damage metric. By examining the vibrational behavior of these tiles and the composite lay-up with Finite Element Modeling and analytical plate vibration equations, the development of a new Nondestructive Evaluation technique is possible. This study examines the development of the Air-Coupled Ultrasonic Resonance Imaging technique as applied to a hexagonal ceramic tile and a multi-material, multi-layered composite.

  3. Material properties of interfacial silicate layer and its influence on the electrical characteristics of MOS devices using hafnia as the gate dielectric

    International Nuclear Information System (INIS)

    This work deals with some fundamental material properties of the hafnia or hafnium oxide and the silicate layer at the Si/HfO2 interface. It is realized that one of the fundamental features of the HfO2 film is that its lowest conduction band states are composed mainly by d states instead of s and p states as is in the case for SiO2. There is only a very small covalent component contributed from Hf d and O 2p states and the Hf-O bond is predominantly ionic. This is the reason for the small band gap and small conduction band offset energy. This feature also gives rise to thermal instabilities and the formation of an interfacial silicate layer. Although the formation of the silicate structure will help to build a more stable interface, long metallic silicide bonds will result as a by-product when the metal oxide reacts with the Si substrate to form this silicate layer. The existence of metallic silicide bonds is one of the major reasons for the observed high-interface trap density of the HfO2/Si structure. Because of the large difference in dielectric constant between the bulk hafnia and interfacial silicate, the electric field will be distributed mainly across the low-? interface layer, which in effect reduces the interface barrier height for electron tunneling injection and the effective breakdown voltage of the low-? layer

  4. The performance of a two-layer biotrickling filter filled with new mixed packing materials for the removal of H2S from air.

    Science.gov (United States)

    Chen, Yingwen; Wang, Xiaojun; He, Shuo; Zhu, Shemin; Shen, Shubao

    2016-01-01

    In the work described here, a two-layer biotrickling filter filled with new packing materials was used to remove H2S from air. The upper layer of the filter was packed with activated carbon-loaded polyurethane, whereas the lower layer was filled with modified organism-suspended fillers. The effects of inlet load, empty bed residence time (EBRT) from 79 s to 53 s, pH and contaminant starvation time were investigated. For loads of 15-50 g/(m(3) h), the average removal efficiency (RE) was higher than 96% under a consistent supply of pollutants. The critical elimination capacity was 39.95 g/(m(3) h) for an EBRT of 53 s with an RE of 99.9%. The two-layer BTF was capable of withstanding contaminant starvation periods for 1.5 d and 7 d with only a few hours of recovery time. The biodegradation kinetics was studied using Michaelis-Menten type equations under different EBRTs. At an EBRT of 66 s, the optimal kinetic constants rmax and Km were 333.3 g/(m(3) h) and 0.93 g/m(3), respectively. During the operation, the two-layer BTF performed well under various reasonable conditions. PMID:26397031

  5. Spherical natural graphite coated by a thick layer of carbonaceous mesophase for use as an anode material in lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wan, C.Y.; Li, H.; Wu, M.C.; Zhao, C.J. [Shanghai Institute of Technology, Shanghai (China)

    2009-07-15

    A method for coating a thick layer of carbonaceous mesophase was developed to treat spherical natural graphite (SNG) for use as anodes in lithium ion batteries. The carbonaceous mesophase layer was fabricated by heat treatment of a mixture of SNG and coal tar pitch. The thickness of the carbonaceous mesophase on the surface of the SNG was approximately 2.5 {mu} m, which is effective for enhancing the strength of the carbonaceous mesophase shell and for allowing the shell to maintain good integrity at a high anode density (1.6 g cm{sup -3}). The mesophase layer increased the initial columbic efficiency from approximately 90% to 95%, dramatically improved the capacity retention and reduced the irreversible capacity by greatly decreasing the SNG surface area. The initial efficiency, cycle life and rate capability for the SNG anode covered by a thick mesophase layer gave comparable results as the mesocarbon microbeads (MCMB) anode, while the SNG anode reversible capacity of 341 mAh g{sup -1} was higher than that of MCMB, 319 mAh g{sup -1}. Electrochemical measurements showed that SNG particles coated by a thick carbonaceous mesophase layer are strong candidates for use as possible anode materials in high energy density lithium ion batteries.

  6. Study of materials for using at waste layer in repositories; Estudo de materiais para uso em camada de recheio em repositorios

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, Andre F., E-mail: marau666@hotmail.co [Universidade Federal de Ouro Preto, MG (Brazil). Escola de Engenharia; Tello, Cledola C.O. de [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil). Servico de Gerencia de Rejeitos

    2009-07-01

    This research has an objective to characterize Brazilian clays and to implant a data base containing the information obtained form tests and suppliers. Such information will allow to buy and and to select optimum material for its utilization in the stuffing layer. Brazilian suppliers were contacted for obtaining information and samples, the various clays were tested and these tests comprehend the following: identification of the mineral constituents, determination of the compaction curve as function of the humidity, hydraulic conductivity, humidity and organic material contents, cationic exchange capacity, specific surface, and etc

  7. Micro-Raman Spectroscopy of Mechanically Exfoliated Few-Quintuple Layers of Bi(2)Te(3), Bi(2)Se(3) and Sb(2)Te(3) Materials

    OpenAIRE

    Shahil, K. M. F.; Hossain, M. Z.; Goyal, V.; Balandin, A. A.

    2012-01-01

    Bismuth telluride - Bi(2)Te(3)- and related compounds have recently attracted strong interest owing to the discovery of the topological insulator properties in many members of this family of materials. The few-quintuple films of these materials are particularly interesting from the physics point of view. We report results of the micro-Raman spectroscopy study of the "graphene-like" exfoliated few-quintuple layers of Bi(2)Te(3), Bi(2)Se(3) and Sb(2)Te(3). It is found that cry...

  8. Analysis of the characteristics of a white organic LED using the newly synthesized blue material methyl-DPVT by varying the thickness of the DPVBi layer

    International Nuclear Information System (INIS)

    A two-wavelength type of white organic light-emitting diode (OLED) having a blue/orange emitting layer was fabricated by synthesizing Methyl-DPVT, a new derivative of the blue-emitting material DPVBi on the market. The white-emission of the two-wavelength type was successfully obtained by representing not only blue emission by using DPVBi but also orange emission by using methyl-DPVT as a host material and Rubrene as a guest material. The basic structure of the fabricated white OLED is glass/ITO/NPB(150 A)/DPVBi/methyl-DPVT :Rubrene [2.0 wt%](100 A)/BCP(70 A)/Alq3(150 A)/Al(600 A). To evaluate the characteristics of the devices, we varied the thickness of the DPVBi layer from 100 A to 80 A to 60 A. A nearly pure white-emission was obtained in CIE coordinates of (0.3327, 0.3397) when the DPVBi layer was 60-A thick at an applied voltage of 11 V. The device started to operate at 1 V and to emit light at 2.5 V. The external quantum efficiency was above 0.5 % both when almost all of the current was injected and the applied voltage was over 10 V. A superior maximum quantum effciency of 0.746 % was obtained at an applied voltage of 18.5 V.

  9. Laser induced forward transfer aluminum layers: Process investigation by time resolved imaging

    Energy Technology Data Exchange (ETDEWEB)

    Mattle, Thomas [General Energies Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Shaw-Stewart, James [General Energies Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Laboratory for Functional Polymers, Empa Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Schneider, Christof W. [General Energies Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Lippert, Thomas, E-mail: thomas.lippert@psi.ch [General Energies Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Wokaun, Alexander [General Energies Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Side- and front-on shadowgraphy. Black-Right-Pointing-Pointer Aluminum flyer is ejected intact for all tested energies. Black-Right-Pointing-Pointer Indications of bending of the aluminum flyer are shown. - Abstract: Laser induced forward transfer of an aluminum thin film on a triazene polymer as a sacrificial layer has been studied with time resolved imaging. Both side- and front-on imaging of the process give a more detailed understanding of the stability of the ejected material during flight. For high fluence ablation (800 mJ/cm{sup 2}) the flyer is stable for 400 ns and gets decomposed completely when interacting with the shockwave after 1 {mu}s. Material detachments on the edges of the flyer are observed at an early stage of the ablation process (<200 ns) which leads to a pixel smaller than its ablation cross section. For low laser fluence (200 mJ/cm{sup 2}) the flyer has the size of the ablation spot and keeps its shape for nearly 1 {mu}s. The back pressure of the decomposed triazene polymer bends the flyer towards the direction of flight and indications for folding are observed.

  10. Thin film capillary process and apparatus

    Science.gov (United States)

    Yu, Conrad M.

    2003-11-18

    Method and system of forming microfluidic capillaries in a variety of substrate materials. A first layer of a material such as silicon dioxide is applied to a channel etched in substrate. A second, sacrificial layer of a material such as a polymer is deposited on the first layer. A third layer which may be of the same material as the first layer is placed on the second layer. The sacrificial layer is removed to form a smooth walled capillary in the substrate.

  11. 3D hierarchical computational model of wood as a cellular material with fibril reinforced, heterogeneous multiple layers

    DEFF Research Database (Denmark)

    Qing, Hai; Mishnaevsky, Leon

    2009-01-01

    A 3D hierarchical computational model of deformation and stiffness of wood, which takes into account the structures of wood at several scale levels (cellularity, multilayered nature of cell walls, composite-like structures of the wall layers) is developed. At the mesoscale, the softwood cell is presented as a 3D hexagon-shape-tube with multilayered walls. The layers in the softwood cell are considered as considered as composite reinforced by microfibrils (celluloses). The elastic properties of the layers are determined with Halpin–Tsai equations, and introduced into mesoscale finite element cellular model. With the use of the developed hierarchical model, the influence of the microstructure, including microfibril angles (MFAs, which characterizes the orientation of the cellulose fibrils with respect to the cell axis), the thickness of the cell wall, the shape of the cell cross-section and the cell dimension (wood density), on the elastic properties of softwood was studied.

  12. Hole transporting material 5, 10, 15-tribenzyl-5H-diindolo[3, 2-a:3?, 2?-c]-carbazole for efficient optoelectronic applications as an active layer

    International Nuclear Information System (INIS)

    In order to explore the novel application of the transparent hole-transporting material 5,10,15-tribenzyl-5H-diindolo[3,2-a:3?,2?-c]-carbazole (TBDI), in this article TBDI is used as an active layer but not a buffer layer in a photodetector (PD), organic light-emitting diode (OLED), and organic photovoltaic cell (OPV) for the first time. Firstly, the absorption and emission spectra of a blend layer comprised of TBDI and electron-transporting material bis-(2-methyl-8-quinolinate) 4-phenylphenolate (BAlq) are investigated. Based on the absorption properties, an organic PD with a peak absorption at 320 nm is fabricated, and a relatively-high detectivity of 2.44 × 1011 cm·Hz1/2/W under 320-nm illumination is obtained. The TBDI/tris (8-hydroxyquinoline) aluminum (Alq3) OLED device exhibits a comparable external quantum efficiency and current efficiency to a traditional 4, 4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (?-NPD)/Alq3 OLED. A C70-based Schottky junction with 5 wt%-TBDI yields a power conversion efficiency of 5.0%, which is much higher than 1.7% for an ?-NPD-based junction in the same configuration. These results suggest that TBDI has some promising properties which are in favor of the hole-transporting in Schottky junctions with a low-concentration donor. (paper)

  13. Improving cycling performance of Li-rich layered cathode materials through combination of Al2O3-based surface modification and stepwise precycling

    Science.gov (United States)

    Kobayashi, Genki; Irii, Yuta; Matsumoto, Futoshi; Ito, Atsushi; Ohsawa, Yasuhiko; Yamamoto, Shinji; Cui, Yitao; Son, Jin-Young; Sato, Yuichi

    2016-01-01

    Controlling a cathode/electrolyte interface by modifying the surface of a cathode material with metal oxides or phosphates is a concept being explored as a possible strategy for improving the electrochemical performance of such materials. This study therefore looks at the crystal structure and chemical bonding state from bulk to surface of Al2O3-coated Li[Li0.2Ni0.18Co0.03Mn0.58]O2 and explores the influence that surface modification has on the electrochemical performance. Investigation by X-ray diffraction, hard X-ray photoelectron spectroscopy (HAXPES) and galvanostatic charge/discharge reaction reveals that the surface-modification layer is composed of Li-Al oxides and Al oxides, with a LiM1-xAlxO2 (M = transition metal) interlayer formed between the modification layer and Li[Li0.2Ni0.18Co0.03Mn0.58]O2 particles. The cycling performance of the Li-rich layered oxide is enhanced by its surface modification with Al2O3, achieving a discharge capacity of more than 310 mA h-1 and excellent cycling stability at 50 °C when combined with a more gradual Li-insertion/de-insertion process (i.e., stepwise precycling treatment).

  14. Structural, mechanical and magnetic properties studies on high-energy Kr-ion irradiated Fe3O4 material (main corrosion layer of Fe-based alloys)

    Science.gov (United States)

    Sun, Jianrong; Wang, Zhiguang; Zhang, Hongpeng; Song, Peng; Chang, Hailong; Cui, Minghuan; Pang, Lilong; Zhu, Yabin; Li, Fashen

    2014-12-01

    The Fe-based (T91 and RAFM) alloys are considered as the promising candidate structural materials for DEMO and the first fusion power plant, and these two kinds of steels suffered more serious corrosion attack at 450 °C in liquid PbBi metal. So in order to further clarify the applicability of Fe-based structural materials in nuclear facilities, we should study not only the alloys itself but also its corrosion layers; and in order to simplify the discussion and clarify the irradiation effects of the different corrosion layer, we abstract the Fe3O4 (main corrosion layer of Fe-based alloys) to study the structural, micro-mechanical and magnetic properties under 2.03 GeV Kr-ion irradiation. The initial crystallographic structure of the Fe3O4 remains unaffected after irradiation at low damage levels, but as the Kr-ion fluence increases and the defects accumulate, the macroscopic magnetic properties (Ms, Hc, etc.) and micro-mechanical properties (nano-hardness and Young's modulus) are sensitive to high-energy Kr-ion irradiation and exhibit excruciating uniform changing regularities with varying fluences (firstly increases, then decreases). And these magnetism, hardening and softening phenomena can be interpreted very well by the effects related to the stress and defects (the production, accumulation and free) induced by high-energy ions irradiation.

  15. Aggregation capability of fluidised layer of granular material during treatment of water with high DOC and low alkalinity.

    Czech Academy of Sciences Publication Activity Database

    Pivokonský, Martin; Pivokonská, Lenka; Tomášková, Hana

    Toulouse : International Water Association, 2007, s. 1-8. [IWA International Conference on Particle Separation. Toulouse (FR), 09.07.2007-11.07.2007] R&D Projects: GA ?R GA103/07/1016; GA AV ?R KJB200600501 Institutional research plan: CEZ:AV0Z20600510 Keywords : agitation * fluidised layer * filtration * water treatment Subject RIV: DJ - Water Pollution ; Quality

  16. Aggregation capability of a fluidised layer of granular material during treatment of water with high DOC and low alkalinity.

    Czech Academy of Sciences Publication Activity Database

    Pivokonský, Martin; Pivokonská, Lenka; Tomášková, Hana

    2008-01-01

    Ro?. 8, ?. 1 (2008), s. 9-17. ISSN 1606-9749 R&D Projects: GA ?R GA103/07/1016 Institutional research plan: CEZ:AV0Z20600510 Keywords : water treatment * aggregation * fluidised layer * agitation Subject RIV: BK - Fluid Dynamics

  17. A fluidized layer of granular material used for the separation of particulate impurities in drinking water treatment.

    Czech Academy of Sciences Publication Activity Database

    Pivokonský, Martin; Bubáková, Petra; Hna?uková, Petra; Knesl, Bohuslav

    2011-01-01

    Ro?. 59, ?. 2 (2011), s. 95-106. ISSN 0042-790X R&D Projects: GA AV ?R IAA200600902 Institutional research plan: CEZ:AV0Z20600510 Keywords : aggregation * destabilization * fluidized layer * separation * water treatment Subject RIV: BK - Fluid Dynamics Impact factor: 0.340, year: 2011

  18. Thin Al2O3 barrier coatings grown on bio-based packaging materials by atomic layer deposition

    OpenAIRE

    Hirvikorpi, Terhi

    2011-01-01

    Growing environmental concerns related to the use of synthetic non-biodegradable polymers in the packaging industry have led to the need for new, especially bio-based, materials. Currently, petroleum-based synthetic polymers are widely used due to their relatively low cost and high performance. Biodegradable plastics and fibre-based materials have been proposed as a solution to the waste problems related to these synthetic polymers. Fibre-based packaging materials have many advantages over th...

  19. Detrimental influence of catalyst seeding on the device properties of CVD-grown 2D layered materials: A case study on MoSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Utama, M. Iqbal Bakti; Lu, Xin; Yuan, Yanwen [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Xiong, Qihua, E-mail: Qihua@ntu.edu.sg [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2014-12-22

    Seed catalyst such as perylene-3,4,9,10-tetracarboxylic acid tetrapotassium (PTAS) salt has been used for promoting the growth of atomically thin layered materials in chemical vapor deposition (CVD) synthesis. However, the ramifications from the usage of such catalyst are not known comprehensively. Here, we report the influence of PTAS seeding on the transistor device performance from few-layered CVD-grown molybdenum diselenide (MoSe{sub 2}) flakes. While better repeatability and higher yield can be obtained with the use of PTAS seeds in synthesis, we observed that PTAS-seeded flakes contain particle impurities. Moreover, devices from PTAS-seeded MoSe{sub 2} flakes consistently displayed poorer field-effect mobility, current on-off ratio, and subthreshold swing as compared to unseeded flakes.

  20. Detrimental influence of catalyst seeding on the device properties of CVD-grown 2D layered materials: A case study on MoSe2

    International Nuclear Information System (INIS)

    Seed catalyst such as perylene-3,4,9,10-tetracarboxylic acid tetrapotassium (PTAS) salt has been used for promoting the growth of atomically thin layered materials in chemical vapor deposition (CVD) synthesis. However, the ramifications from the usage of such catalyst are not known comprehensively. Here, we report the influence of PTAS seeding on the transistor device performance from few-layered CVD-grown molybdenum diselenide (MoSe2) flakes. While better repeatability and higher yield can be obtained with the use of PTAS seeds in synthesis, we observed that PTAS-seeded flakes contain particle impurities. Moreover, devices from PTAS-seeded MoSe2 flakes consistently displayed poorer field-effect mobility, current on-off ratio, and subthreshold swing as compared to unseeded flakes

  1. Study on metal microparticle content of the material transferred with Absorbing Film Assisted Laser Induced Forward Transfer when using silver absorbing layer

    Energy Technology Data Exchange (ETDEWEB)

    Smausz, T. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: tomi@physx.u-szeged.hu; Hopp, B. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Kecskemeti, G. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Bor, Z. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)

    2006-04-30

    Absorbing Film Assisted Laser Induced Forward Transfer (AFA-LIFT) is a modified LIFT method where a high absorption coefficient thin film coating of a transparent substrate is used to transform the laser energy into kinetic in order to transfer the 'target' material spread on it. This method can be used for the transfer of biomaterials and living cells, which could be damaged by direct irradiation of the laser beam. In previous experiments, {approx}50-100 nm thick metal films have been used as absorbing layer. The transferred material can also contain metal microparticles originating from the absorbing thin film and acting as non-desired impurities in some cases. The aim of our work was to study how the properties (number, size and covered area) of metal particles transferred during the AFA-LIFT process depend on film thickness and the applied fluence. Silver thin films with different thickness (50-400 nm) were used as absorbing layers and real experimental conditions were modeled by a 100 {mu}m thick water layer. The particles transferred without the use of water layer were also studied. The threshold laser fluence for the complete removal of the absorber from the irradiated area was found to strongly increase with increasing film thickness. The deposited micrometer and submicrometer particles were observed with optical microscope and atomic force microscope. Their size ranged from 100 nm to 20 {mu}m and depended on the laser fluence. The increase in fluence resulted in an increasing number of particles of smaller average size.

  2. A difference in using atomic layer deposition or physical vapour deposition TiN as electrode material in metal-insulator-metal and metal-insulator-silicon capacitors.

    Science.gov (United States)

    Groenland, A W; Wolters, R A M; Kovalgin, A Y; Schmitz, J

    2011-09-01

    In this work, metal-insulator-metal (MIM) and metal-insulator-silicon (MIS) capacitors are studied using titanium nitride (TiN) as the electrode material. The effect of structural defects on the electrical properties on MIS and MIM capacitors is studied for various electrode configurations. In the MIM capacitors the bottom electrode is a patterned 100 nm TiN layer (called BE type 1), deposited via sputtering, while MIS capacitors have a flat bottom electrode (called BE type 2-silicon substrate). A high quality 50-100 nm thick SiO2 layer, made by inductively-coupled plasma CVD at 150 degrees C, is deposited as a dielectric on top of both types of bottom electrodes. BE type 1 (MIM) capacitors have a varying from low to high concentration of structural defects in the SiO2 layer. BE type 2 (MIS) capacitors have a low concentration of structural defects and are used as a reference. Two sets of each capacitor design are fabricated with the TiN top electrode deposited either via physical vapour deposition (PVD, i.e., sputtering) or atomic layer deposition (ALD). The MIM and MIS capacitors are electrically characterized in terms of the leakage current at an electric field of 0.1 MV/cm (I leak) and for different structural defect concentrations. It is shown that the structural defects only show up in the electrical characteristics of BE type 1 capacitors with an ALD TiN-based top electrode. This is due to the excellent step coverage of the ALD process. This work clearly demonstrates the sensitivity to process-induced structural defects, when ALD is used as a step in process integration of conductors on insulation materials. PMID:22097586

  3. Alternating-current losses in two-layer superconducting cables consisting of second-generation superconductors coated by U-shaped ferromagnetic materials

    International Nuclear Information System (INIS)

    Alternating-current losses in a two-layer superconducting cable, each layer being composed of 15 closely-spaced rectangular wires made up of second-generation superconductors when the ends of wires are coated by either a non-magnetic or strong ferromagnetic material having a U profile is numerically investigated. Computations are carried out through the finite-element method. The alternating-current losses do not increase significantly if the relative permeability of the coating is increased three orders of magnitude, provided that the current amplitude is less than half of the critical current in a superconducting wire. However, the losses are much higher for ferromagnetic coating if the amplitude of the applied current oscillating at 50 Hz is close to the critical current. The ferromagnetic coating is seen to accumulate the magnetic field lines normally on its surfaces, while the field lines are parallel to the long axes of the wires, leading to more significant flux penetration in the coated regions. This facilitates a uniform low-loss current flow in the uncoated regions of the wires. In contrast, coating with a non-magnetic material gives rise to a considerably smaller current flow in the uncoated regions, whereas the low-loss flow is maintained in the coated regions. Moreover, the current flows in opposite directions in the coated and uncoated regions, where the direction in each region is converse for the two materials. (interdisciplinary physics and related areas of science and technology)

  4. Efficient blue-green and green electroluminescent devices obtained by doping iridium complexes into hole-block material as supplementary light-emitting layer

    International Nuclear Information System (INIS)

    In this work, organic electroluminescent (EL) devices with dominant and supplementary light-emitting layers (EMLs) were designed to further improve the EL performances of two iridiumIII-based phosphorescent complexes, which have been reported to provide EL devices with slow EL efficiency roll-off. The widely used hole-block material 2,2?,2''-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) was selected as host material to construct the supplementary EML. Compared with single-EML devices, double-EMLs devices showed higher EL efficiencies, higher brightness, and lower operation voltage attributed to wider recombination zone and better balance of carriers. In addition, the insertion of supplementary EML is instrumental in facilitating carriers trapping, thus improving the color purity. Finally, high performance blue-green and green EL devices with maximum current efficiencies of 35.22 and 90.68 cd/A, maximum power efficiencies of 26.36 and 98.18 lm/W, and maximum brightness of 56,678 and 112,352 cd/m2, respectively, were obtained by optimizing the doping concentrations. Such a device design strategy extends the application of a double EML device structure and provides a chance to simplify device fabrication processes. -- Highlights: • Electroluminescent devices with supplementary light-emitting layer were fabricated. • Doping concentrations and thicknesses were optimized. • Better balance of holes and electrons causes the enhanced efficiency. • Improved carrier trapping suppresses the emission of host material

  5. Downscaling the Sample Thickness to Sub-Micrometers by Employing Organic Photovoltaic Materials as a Charge-Generation Layer in the Time-of-Flight Measurement

    Science.gov (United States)

    Liu, Shun-Wei; Lee, Chih-Chien; Su, Wei-Cheng; Yuan, Chih-Hsien; Lin, Chun-Feng; Chen, Kuan-Ting; Shu, Yi-Sheng; Li, Ya-Ze; Su, Tsung-Hao; Huang, Bo-Yao; Chang, Wen-Chang; Liu, Yu-Hsuan

    2015-05-01

    Time-of-flight (TOF) measurements typically require a sample thickness of several micrometers for determining the carrier mobility, thus rendering the applicability inefficient and unreliable because the sample thicknesses are orders of magnitude higher than those in real optoelectronic devices. Here, we use subphthalocyanine (SubPc):C70 as a charge-generation layer (CGL) in the TOF measurement and a commonly hole-transporting layer, N,N’-diphenyl-N,N’-bis(1,1’-biphenyl)-4,4’-diamine (NPB), as a standard material under test. When the NPB thickness is reduced from 2 to 0.3??m and with a thin 10-nm CGL, the hole transient signal still shows non-dispersive properties under various applied fields, and thus the hole mobility is determined accordingly. Only 1-?m NPB is required for determining the electron mobility by using the proposed CGL. Both the thicknesses are the thinnest value reported to data. In addition, the flexibility of fabrication process of small molecules can deposit the proposed CGL underneath and atop the material under test. Therefore, this technique is applicable to small-molecule and polymeric materials. We also propose a new approach to design the TOF sample using an optical simulation. These results strongly demonstrate that the proposed technique is valuable tool in determining the carrier mobility and may spur additional research in this field.

  6. Properties of SiC and problems of the material for use as the coating layer of fuel particles

    International Nuclear Information System (INIS)

    The properties of silicon carbide (SiC) reported in the literatures and obtained in the authors' experiments, are reviewed with a view to improving the SiC coating layer of fuel particles for HTGR. Described are the deposition, physical and chemical properties, mechanical strength, diffusion and irradiation behaviors. The experimental results obtained in the authors' laboratory in in-pile irradiation and out-of-pile annealing of the SiC-coated particles are also presented. (auth.)

  7. Polyimide as a versatile enabling material for microsystems fabrication: surface micromachining and electrodeposited nanowires integration

    Science.gov (United States)

    Walewyns, Thomas; Reckinger, Nicolas; Ryelandt, Sophie; Pardoen, Thomas; Raskin, Jean-Pierre; Francis, Laurent A.

    2013-09-01

    The interest of using polyimide as a sacrificial and anchoring layer is demonstrated for post-processing surface micromachining and for the incorporation of metallic nanowires into microsystems. In addition to properties like a high planarization factor, a good resistance to most non-oxidizing acids and bases, and CMOS compatibility, polyimide can also be used as a mold for nanostructures after ion track-etching. Moreover, specific polyimide grades, such as PI-2611 from HD Microsystems™, involve a thermal expansion coefficient similar to silicon and low internal stress. The process developed in this study permits higher gaps compared to the state-of-the-art, limits stiction problems with the substrate and is adapted to various top-layer materials. Most metals, semiconductors or ceramics will not be affected by the oxygen plasma required for polyimide etching. Released structures with vertical gaps from one to several tens of ?m have been obtained, possibly using multiple layers of polyimide. Furthermore, patterned freestanding nanowires have been synthesized with diameters from 20 to 60?nm and up to 3??m in length. These results have been applied to the fabrication of two specific devices: a generic nanomechanical testing lab-on-chip platform and a miniaturized ionization sensor.

  8. Directing Hybrid Structures by Combining Self-Assembly of Functional Block Copolymers and Atomic Layer Deposition: A Demonstration on Hybrid Photovoltaics.

    Science.gov (United States)

    Moshonov, Moshe; Frey, Gitti L

    2015-11-24

    The simplicity and versatility of block copolymer self-assembly offers their use as templates for nano- and meso-structured materials. However, in most cases, the material processing requires multiple steps, and the block copolymer is a sacrificial building block. Here, we combine a self-assembled block copolymer template and atomic layer deposition (ALD) of a metal oxide to generate functional hybrid films in a simple process with no etching or burning steps. This approach is demonstrated by using the crystallization-induced self-assembly of a rod-coil block copolymer, P3HT-b-PEO, and the ALD of ZnO. The block copolymer self-assembles into fibrils, ? 20 nm in diameter and microns long, with crystalline P3HT cores and amorphous PEO corona. The affinity of the ALD precursors to the PEO corona directs the exclusive deposition of crystalline ZnO within the PEO domains. The obtained hybrid structure possesses the properties desired for photovoltaic films: donor-acceptor continuous nanoscale interpenetrated networks. Therefore, we integrated the films into single-layer hybrid photovoltaics devices, thus demonstrating that combining self-assembly of functional block copolymers and ALD is a simple approach to direct desired complex hybrid morphologies. PMID:26523422

  9. Effect of gradient dielectric coefficient in a functionally graded material (FGM) substrate on the propagation behavior of love waves in an FGM-piezoelectric layered structure.

    Science.gov (United States)

    Cao, Xiaoshan; Shi, Junping; Jin, Feng

    2012-06-01

    The propagation behavior of Love waves in a layered structure that includes a functionally graded material (FGM) substrate carrying a piezoelectric thin film is investigated. Analytical solutions are obtained for both constant and gradient dielectric coefficients in the FGM substrate. Numerical results show that the gradient dielectric coefficient decreases phase velocity in any mode, and the electromechanical coupling factor significantly increases in the first- and secondorder modes. In some modes, the difference in Love waves' phase velocity between these two types of structure might be more than 1%, resulting in significant differences in frequency of the surface acoustic wave devices. PMID:22718875

  10. Radiotracer technique to study effectiveness of the three layer lining in the solar pond at the Rare Materials Project, BARC, Mysore

    International Nuclear Information System (INIS)

    Radioisotopes are commonly used as tracers for identifying origin of seepages, interconnection between water bodies and various hydrological investigations. Advantage of radiotracers over other tracers is that they can be detected at very minute concentrations. Tritiated water as a radiotracer is used for water tracing purpose as it exactly follows water, conservative in nature, and have same physical chemical characteristics and thus regarded as the ideal tracer for water tracing purpose. Tritiated water was used as a tracer to study the effectiveness of the three layer lining carried out in one of the solar pond at the Rare Materials Project, Bhabha Atomic Research Centre (BARC), Mysore. (author)

  11. First photoresponsive liquid crystalline materials with small layer shrinkage at the phase transition to the ferroelectric phase.

    Czech Academy of Sciences Publication Activity Database

    Novotná, Vladimíra; Hamplová, V?ra; Bubnov, Alexej; Kašpar, Miroslav; Glogarová, Milada; Kapernaum, N.; Bezner, S.; Giesselmann, F.

    2009-01-01

    Ro?. 19, ?. 23 (2009), s. 3992-3997. ISSN 0959-9428 R&D Projects: GA MŠk MEB050818; GA AV ?R IAA100100710; GA MŠk OC 175; GA AV ?R(CZ) GA202/09/0047 Grant ostatní: DAAD-AV?R(XE) D7-CZ8/08-09 DAAD-AV CR Institutional research plan: CEZ:AV0Z10100520 Keywords : photosensitive * liquid crystals * De Vries behaviour * layer shrinkage Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.795, year: 2009

  12. High-affinity sulfonated materials with transition metal counterions for enhanced protein separation in dual-layer hollow fiber membrane chromatography.

    Science.gov (United States)

    Li, Yi; Chung, Tai-Shung; Chan, Sui Yung

    2008-04-11

    High-affinity membrane materials have been successfully synthesized through a combination of the polymer sulfonation reaction with transition metal counterion exchange treatment. This type of promising materials were embodied for the first time with the aid of dual-layer hollow fiber technology for protein separation. Three types of immobilized metal affinity membranes (Cu(2+), Ni(2+) and Zn(2+) forms) were developed in this work and they all exhibited enhanced protein separation performance compared to the as-spun hollow fiber in H(+) form due to the strong affinity between transition metal counterions and target protein molecules. Ultimately, the high-purity target protein (>99%, w/w) could be achieved via the membrane in Cu(2+) form. PMID:18313679

  13. Catalytic Graphitization for Preparation of Porous Carbon Material Derived from Bamboo Precursor and Performance as Electrode of Electrical Double-Layer Capacitor

    Science.gov (United States)

    Tsubota, Toshiki; Maguchi, Yuta; Kamimura, Sunao; Ohno, Teruhisa; Yasuoka, Takehiro; Nishida, Haruo

    2015-12-01

    The combination of addition of Fe (as a catalyst for graphitization) and CO2 activation (a kind of gaseous activation) was applied to prepare a porous carbon material from bamboo powder (a waste product of superheated steam treatment). Regardless of the heat treatment temperature, many macropores were successfully formed after the heating process by removal of Fe compounds. A turbostratic carbon structure was generated in the Fe-added sample heated at 850°C. It was confirmed that the added Fe acted as a template for pore formation. Moreover, it was confirmed that the added Fe acted as a catalyst for graphitization. The resulting electrochemical performance as the electrode of an electrical double-layer capacitor, as demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy, and charge-discharge testing, could be explained based on the graphitization and activation effects. Addition of Fe could affect the electrical properties of carbon material derived from bamboo.

  14. Improvement of the Cycling Performance and Thermal Stability of Lithium-Ion Cells by Double-Layer Coating of Cathode Materials with Al?O? Nanoparticles and Conductive Polymer.

    Science.gov (United States)

    Lee, Yoon-Sung; Shin, Won-Kyung; Kannan, Aravindaraj G; Koo, Sang Man; Kim, Dong-Won

    2015-07-01

    We demonstrate the effectiveness of dual-layer coating of cathode active materials for improving the cycling performance and thermal stability of lithium-ion cells. Layered nickel-rich LiNi0.6Co0.2Mn0.2O2 cathode material was synthesized and double-layer coated with alumina nanoparticles and poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol). The lithium-ion cells assembled with a graphite negative electrode and a double-layer-coated LiNi0.6Co0.2Mn0.2O2 positive electrode exhibited high discharge capacity, good cycling stability, and improved rate capability. The protective double layer formed on the surface of LiNi0.6Co0.2Mn0.2O2 materials effectively inhibited the dissolution of Ni, Co, and Mn metals from cathode active materials and improved thermal stability by suppressing direct contact between electrolyte solution and delithiated Li(1-x)Ni0.6Co0.2Mn0.2O2 materials. This effective design strategy can be adopted to enhance the cycling performance and thermal stability of other layered nickel-rich cathode materials used in lithium-ion batteries. PMID:26083766

  15. Design of Microporous Material HUS-10 with Tunable Hydrophilicity, Molecular Sieving, and CO2 Adsorption Ability Derived from Interlayer Silylation of Layered Silicate HUS-2.

    Science.gov (United States)

    Tsunoji, Nao; Yuki, Sota; Oumi, Yasunori; Sekikawa, Miyuki; Sasaki, Yukichi; Sadakane, Masahiro; Sano, Tsuneji

    2015-11-01

    The attractive properties of zeolites, which make them suitable for numerous applications for the energy and chemical industries and for life sciences, are derived from their crystalline framework structures. Herein, we describe the rational synthesis of a microporous material, HUS-10, utilizing a layered silicate precursor, HUS-2, as a structural building unit. For the ordered micropores to be formed, interlayer pillars that supported the original silicate layer of HUS-2 were immobilized through the interlayer silylation of silanol groups with trichloromethylsilane and a subsequent dehydration-condensation reaction of the hydroxyl groups on the preintroduced tetrahedral units. An actual molecular sieving ability, enabling the adsorption of molecules smaller than ethane, was confirmed in the ordered micropores of HUS-10. The hydrophilic adsorption could also be controlled by changing the number of methyl and hydroxyl groups in the immobilized interlayer pillars. In addition, when the adsorption behaviors of CO2, CH4, and N2 on HUS-10 were compared to those on siliceous MFI and CDO zeolites with approximately the same pore diameter, the CO2 adsorption capacity of HUS-10 was comparable. Conversely, because of the adsorption inhibition of CH4 and N2, HUS-10 exhibited larger CO2/CH4 and CO2/N2 adsorption ratios relative to those of MFI and CDO zeolites. These results reveal that the unique microporous framework structure presented by the rational structural design using the layered silicate precursor HUS-2 has the potential to separate CO2 from gas mixtures. PMID:26479449

  16. Incorporating a hole-transport material into the emissive layer of solid-state light-emitting electrochemical cells to improve device performance.

    Science.gov (United States)

    Huang, Po-Chin; Krucaite, Gintare; Su, Hai-Ching; Grigalevicius, Saulius

    2015-07-14

    Solid-state light-emitting electrochemical cells (LECs) based on ionic transition metal complexes (iTMCs) have several advantages such as high efficiency, low operation voltage and simple device structure. To improve the device efficiency of iTMC-based LECs for practical applications, improving the carrier balance to achieve a centered recombination zone would be an important issue. In this work, incorporating a hole-transport material (HTM) into the emissive layer of iTMC-based LECs is shown to improve device performance. When mixed with an HTM (12%), the LECs based on a Ru complex exhibit 1.9× and 1.5× enhancement in peak light output and peak external quantum efficiency (EQE) as compared to neat-film devices. Furthermore, over 2× enhancement in stabilized EQE can be achieved in LECs mixed with an HTM. It is attributed to that a more centered recombination zone in LECs mixed with an HTM is beneficial in reducing exciton quenching in the recombination zone approaching extended doped layers. Estimating the temporal evolution of the recombination zone in the LECs mixed with an HTM by employing the microcavity effect is demonstrated to confirm the physical origin for improved device performance. These results reveal that incorporating of an HTM in the emissive layer of LECs based on an iTMC is a feasible way to improve carrier balance and thus enhance light output and device efficiency. PMID:26074493

  17. Pressure-assisted fabrication of organic light emitting diodes with MoO{sub 3} hole-injection layer materials

    Energy Technology Data Exchange (ETDEWEB)

    Du, J. [The Princeton Institute for the Science and Technology of Materials (PRISM), Princeton, New Jersey 08544 (United States); Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Anye, V. C.; Vodah, E. O. [Department of Materials Science and Engineering, African University of Science and Technology, Abuja, Federal Capital Territory (Nigeria); Tong, T. [The Princeton Institute for the Science and Technology of Materials (PRISM), Princeton, New Jersey 08544 (United States); Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Zebaze Kana, M. G. [Physics Advanced Laboratory, Sheda Science and Technology Complex, Abuja, Federal Capital Territory (Nigeria); Department of Materials Science and Engineering, Kwara State University, Kwara State (Nigeria); Soboyejo, W. O. [The Princeton Institute for the Science and Technology of Materials (PRISM), Princeton, New Jersey 08544 (United States); Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Department of Materials Science and Engineering, African University of Science and Technology, Abuja, Federal Capital Territory (Nigeria)

    2014-06-21

    In this study, pressures of ?5 to ?8?MPa were applied to organic light emitting diodes containing either evaporated molybdenum trioxide (MoO{sub 3}) or spin-coated poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulphonate) (PEDOT:PSS) hole-injection layers (HILs). The threshold voltages for both devices were reduced by about half, after the application of pressure. Furthermore, in an effort to understand the effects of pressure treatment, finite element simulations were used to study the evolution of surface contact between the HIL and emissive layer (EML) under pressure. The blister area due to interfacial impurities was also calculated. This was shown to reduce by about half, when the applied pressures were between ?5 and 8?MPa. The finite element simulations used Young's modulus measurements of MoO{sub 3} that were measured using the nanoindentation technique. They also incorporated measurements of the adhesion energy between the HIL and EML (measured by force microscopy during atomic force microscopy). Within a fracture mechanics framework, the implications of the results are then discussed for the pressure-assisted fabrication of robust organic electronic devices.

  18. Pressure-assisted fabrication of organic light emitting diodes with MoO3 hole-injection layer materials

    International Nuclear Information System (INIS)

    In this study, pressures of ?5 to ?8?MPa were applied to organic light emitting diodes containing either evaporated molybdenum trioxide (MoO3) or spin-coated poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulphonate) (PEDOT:PSS) hole-injection layers (HILs). The threshold voltages for both devices were reduced by about half, after the application of pressure. Furthermore, in an effort to understand the effects of pressure treatment, finite element simulations were used to study the evolution of surface contact between the HIL and emissive layer (EML) under pressure. The blister area due to interfacial impurities was also calculated. This was shown to reduce by about half, when the applied pressures were between ?5 and 8?MPa. The finite element simulations used Young's modulus measurements of MoO3 that were measured using the nanoindentation technique. They also incorporated measurements of the adhesion energy between the HIL and EML (measured by force microscopy during atomic force microscopy). Within a fracture mechanics framework, the implications of the results are then discussed for the pressure-assisted fabrication of robust organic electronic devices.

  19. The ion-exchange property of some layered inorganic materials with potassium ion, rubidium ion and cesium ion, and selective cesium ion-exchange of synthetic mica

    International Nuclear Information System (INIS)

    The ion-exchange property of sodium difluorotetrasilicate, Na-TSM, with potassium, rubidium and cesium ions was investigated in addition to two other typical layered inorganic materials. The selectivity sequence of Na-TSM was Cs+ > Rb+ > K+ and the selectivity difference of Na-TSM was highest among the examined layered materials. It was found from a chemical analysis that cesium ion-exchange participated in magnesium ions, which is a lattice component of Na-TSM, in addition to an ordinary ion-exchange reaction with the interlayer sodium ions. The exchange of cesium ions with magnesium ions was found to be stoichiometric, and was expected to be an ideal ion-exchange reaction. It was a peculiar phenomenon only on Na-TSM> Once cesium ions were exchanged in a Na-TSM lattice, they were hardly released, due to a reverse ion-exchange with sodium ions. The highest selectivity difference and tight binding of cesium ions were interpreted by an ion-exchange with lattice magnesium ion as well as decreased dehydration, which resulted in the interlayer gallery height. (author)

  20. Preparation and Characterization of Hybrid Organic-Inorganic Composite Material: Polymerization of m-Aminobenzoic Acid-Intercalated Into Zn/Al-Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Rasheed M.A.Q. Jamhour

    2005-01-01

    Full Text Available Layered double hydroxides of aluminum and zinc (Zn/Al-LDH’s were synthesized directly by hydrolysis at room temperature as reported elsewhere. After characterization, the material was reacted with m-aminobenzoat anion (m-NH2C6H4COO- which undergoes polymerization in the interlayer space; resulting in the formation of a matrix with polymeric organic macromolecule. The resulting material along with the host LDH’s compound of Zn/Al-Cl was characterized by X-Ray Powder Diffraction (PXRD, Thermal Analysis (TG, Differential Thermal Analysis (DTA, and Fourier Transform Infrared Spectroscopy (FTIR. The study confirms the intercalation of m-aminobenzoat anion. Diffusion of oxygen molecules between the contact region of two anions in the interlayer space and oxidation of the anion lead to the formation of a polymer macromolecule. This intercalation compound result in a gallery height of 15.8 A, indicating that the guest anion stack to form a monolayer with the benzene rings perpendicular to the host layers, giving a suitable orientation for polymerization.

  1. Hole transporting material 5, 10, 15-tribenzyl-5H-diindolo[3, 2-a:3?, 2?-c]-carbazole for efficient optoelectronic applications as an active layer

    Science.gov (United States)

    Zheng, Yan-Qiong; J. Potscavage, William, Jr.; Zhang, Jian-Hua; Wei, Bin; Huang, Rong-Juan

    2015-02-01

    In order to explore the novel application of the transparent hole-transporting material 5,10,15-tribenzyl-5H-diindolo[3,2-a:3?,2?-c]-carbazole (TBDI), in this article TBDI is used as an active layer but not a buffer layer in a photodetector (PD), organic light-emitting diode (OLED), and organic photovoltaic cell (OPV) for the first time. Firstly, the absorption and emission spectra of a blend layer comprised of TBDI and electron-transporting material bis-(2-methyl-8-quinolinate) 4-phenylphenolate (BAlq) are investigated. Based on the absorption properties, an organic PD with a peak absorption at 320 nm is fabricated, and a relatively-high detectivity of 2.44 × 1011 cm·Hz1/2/W under 320-nm illumination is obtained. The TBDI/tris (8-hydroxyquinoline) aluminum (Alq3) OLED device exhibits a comparable external quantum efficiency and current efficiency to a traditional 4, 4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (?-NPD)/Alq3 OLED. A C70-based Schottky junction with 5 wt%-TBDI yields a power conversion efficiency of 5.0%, which is much higher than 1.7% for an ?-NPD-based junction in the same configuration. These results suggest that TBDI has some promising properties which are in favor of the hole-transporting in Schottky junctions with a low-concentration donor. Project supported by the Funding Program for World-Leading Innovative R & D on Science and Technology (FIRST) from JSPS, the Fund from the Science and Technology Commission of Shanghai Municipality, China (Grant Nos. 14DZ2280900 and 14XD1401800), and the Natural Science Foundation of Shanghai (Grant No. 15ZR1416600).

  2. Electrochemical Kinetics and Performance of Layered Composite Cathode Material Li[Li0.2Ni0.2Mn0.6]O2

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jianming; Shi, Wei; Gu, Meng; Xiao, Jie; Zuo, Pengjian; Wang, Chong M.; Zhang, Jiguang

    2013-10-10

    Lithium-rich, manganese-rich (LMR) layered composite cathode material Li[Li0.2Ni0.2Mn0.6]O2 has been successfully prepared by a co-precipitation method and its structure is confirmed by XRD characterization. The material delivers a high discharge capacity of 281 mAh g-1, when charged and discharged at a low current density of 10 mA g-1. However, significant increase of cell polarization and decrease of discharge capacity are observed at voltages below 3.5 V with increasing current densities. Galvanostatic intermittent titration technique (GITT) analysis demonstrates that lithium ion intercalation/de-intercalation reactions in this material are kinetically controlled by Li2MnO3 and its activated MnO2 component. The relationship between the electrochemical kinetics and rate performance as well as cycling stability has been systematically investigated. High discharge capacity of 149 mAh g-1 can be achieved at 10 C charge rate and C/10 discharge rate. The result demonstrates that the Li2MnO3 based material could withstand high charge rate (except initial activation process), which is very promising for practical applications. A lower discharge current density is preferred to overcome the kinetic barrier of lithium ion intercalation into MnO2 component, in order to achieve higher discharge capacity even at high charge rates.

  3. Well-defined hollow nanochanneled-silica nanospheres prepared with the aid of sacrificial copolymer nanospheres and surfactant nanocylinders

    Science.gov (United States)

    Kim, Young Yong; Hwang, Bora; Song, Sungjin; Ree, Brian J.; Kim, Yongjin; Cho, Seo Yeon; Heo, Kyuyoung; Kwon, Yong Ku; Ree, Moonhor

    2015-08-01

    A new approach for synthesizing well-defined hollow nanochanneled-silica nanosphere particles is demonstrated, and the structural details of these particles are described for the first time. Positively charged styrene copolymer nanospheres with a clean, smooth surface and a very narrow size distribution are synthesized by surfactant-free emulsion copolymerization and used as a thermal sacrificial core template for the production of core-shell nanoparticles. A surfactant/silica composite shell with a uniform thickness is successfully produced and deposited onto the polymeric core template by charge density matching between the polymer nanosphere template surface and the negatively charged silica precursors and then followed by selective thermal decomposition of the polymeric core and the surfactant cylinder domains in the shell, producing the hollow nanochanneled-silica nanospheres. Comprehensive, quantitative structural analyses collectively confirm that the obtained nanoparticles are structurally well defined with a hollow core and a shell composed of cylindrical nanochannels that provide facile accessibility to the hollow interior space. Overall, the hollow nanochanneled-silica nanoparticles have great potential for applications in various fields.A new approach for synthesizing well-defined hollow nanochanneled-silica nanosphere particles is demonstrated, and the structural details of these particles are described for the first time. Positively charged styrene copolymer nanospheres with a clean, smooth surface and a very narrow size distribution are synthesized by surfactant-free emulsion copolymerization and used as a thermal sacrificial core template for the production of core-shell nanoparticles. A surfactant/silica composite shell with a uniform thickness is successfully produced and deposited onto the polymeric core template by charge density matching between the polymer nanosphere template surface and the negatively charged silica precursors and then followed by selective thermal decomposition of the polymeric core and the surfactant cylinder domains in the shell, producing the hollow nanochanneled-silica nanospheres. Comprehensive, quantitative structural analyses collectively confirm that the obtained nanoparticles are structurally well defined with a hollow core and a shell composed of cylindrical nanochannels that provide facile accessibility to the hollow interior space. Overall, the hollow nanochanneled-silica nanoparticles have great potential for applications in various fields. Electronic supplementary information (ESI) available: SXS data analysis, GIXS data analysis, GPC data, SXS data and GIXS data are available. See DOI: 10.1039/c5nr03800f

  4. Fabrication of Three Dimensional Tissue Engineering Polydimethylsiloxane ( PDMS) Microporous Scaffolds Integrated in a Bioreactor Using a 3D Printed Water Dissolvable Sacrificial Mould

    DEFF Research Database (Denmark)

    Mohanty, Soumyaranjan; Mantis, Ioannis; Chetan, Aradhya Mallikarjunaiah; Larsen, Layla Bashir; Dufva, Martin; Emnéus, Jenny; Wolff, Anders

    2015-01-01

    We present a new scalable and general approach for manufacturing structured pores/channels in 3D polymer based scaffolds. The method involves 3D printing of a sacrificial polyvinyl alcohol (PVA) mould whose geometrical features are designed according to the required vascular channel network. Polydimethylsiloxane (PDMS) polymer is cast around the PVA mould, cross-linked and then the mould is dissolved, leaving behind a structured porous PDMS scaffold. The fabrication method described here is demo...

  5. Efficient blue-green and green electroluminescent devices obtained by doping iridium complexes into hole-block material as supplementary light-emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Liang [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Zheng, Youxuan, E-mail: yxzheng@mail.nju.edu.cn [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Deng, Ruiping; Feng, Jing; Song, Mingxing; Hao, Zhaomin [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Zhang, Hongjie, E-mail: hongjie@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Zuo, Jinglin; You, Xiaozeng [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2014-04-15

    In this work, organic electroluminescent (EL) devices with dominant and supplementary light-emitting layers (EMLs) were designed to further improve the EL performances of two iridium{sup III}-based phosphorescent complexes, which have been reported to provide EL devices with slow EL efficiency roll-off. The widely used hole-block material 2,2?,2''-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) was selected as host material to construct the supplementary EML. Compared with single-EML devices, double-EMLs devices showed higher EL efficiencies, higher brightness, and lower operation voltage attributed to wider recombination zone and better balance of carriers. In addition, the insertion of supplementary EML is instrumental in facilitating carriers trapping, thus improving the color purity. Finally, high performance blue-green and green EL devices with maximum current efficiencies of 35.22 and 90.68 cd/A, maximum power efficiencies of 26.36 and 98.18 lm/W, and maximum brightness of 56,678 and 112,352 cd/m{sup 2}, respectively, were obtained by optimizing the doping concentrations. Such a device design strategy extends the application of a double EML device structure and provides a chance to simplify device fabrication processes. -- Highlights: • Electroluminescent devices with supplementary light-emitting layer were fabricated. • Doping concentrations and thicknesses were optimized. • Better balance of holes and electrons causes the enhanced efficiency. • Improved carrier trapping suppresses the emission of host material.

  6. Materialism.

    Science.gov (United States)

    Melnyk, Andrew

    2012-05-01

    Materialism is nearly universally assumed by cognitive scientists. Intuitively, materialism says that a person's mental states are nothing over and above his or her material states, while dualism denies this. Philosophers have introduced concepts (e.g., realization and supervenience) to assist in formulating the theses of materialism and dualism with more precision, and distinguished among importantly different versions of each view (e.g., eliminative materialism, substance dualism, and emergentism). They have also clarified the logic of arguments that use empirical findings to support materialism. Finally, they have devised various objections to materialism, objections that therefore serve also as arguments for dualism. These objections typically center around two features of mental states that materialism has had trouble in accommodating. The first feature is intentionality, the property of representing, or being about, objects, properties, and states of affairs external to the mental states. The second feature is phenomenal consciousness, the property possessed by many mental states of there being something it is like for the subject of the mental state to be in that mental state. WIREs Cogn Sci 2012, 3:281-292. doi: 10.1002/wcs.1174 For further resources related to this article, please visit the WIREs website. PMID:26301463

  7. Development of Plasma-Sprayed Molybdenum Carbide-Based Anode Layers with Various Metal Oxides for SOFC

    Science.gov (United States)

    Faisal, N. H.; Ahmed, R.; Katikaneni, S. P.; Souentie, S.; Goosen, M. F. A.

    2015-09-01

    Air plasma-sprayed (APS) coatings provide an ability to deposit a range of novel fuel cell materials at competitive costs. This work develops three separate types of composite anodes (Mo-Mo2C/Al2O3, Mo-Mo2C/ZrO2, Mo-Mo2C/TiO2) using a combination of APS process parameters on Hastelloy®X for application in intermediate temperature proton-conducting solid oxide fuel cells. Commercially available carbide of molybdenum powder catalyst (Mo-Mo2C) and three metal oxides (Al2O3, ZrO2, TiO2) was used to prepare three separate composite feedstock powders to fabricate three different anodes. Each of the modified composition anode feedstock powders included a stoichiometric weight ratio of 0.8:0.2. The coatings were characterized by scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction, nanoindentation, and conductivity. We report herein that three optimized anode layers of thicknesses between 200 and 300 µm and porosity as high as 20% for Mo-Mo2C/Al2O3 (250-µm thick) and Mo-Mo2C/TiO2 (300 µm thick) and 17% for Mo-Mo2C/ZrO2 (220-µm thick), controllable by a selection of the APS process parameters with no addition of sacrificial pore-forming material. The nanohardness results indicate the upper layers of the coatings have higher values than the subsurface layers in coatings with some effect of the deposition on the substrate. Mo-Mo2C/ZrO2 shows high electrical conductivity.

  8. Anisotropic thermoelectric properties of layered compounds in SnX2 (X = S, Se): a promising thermoelectric material.

    Science.gov (United States)

    Sun, Bao-Zhen; Ma, Zuju; He, Chao; Wu, Kechen

    2015-11-28

    Thermoelectrics interconvert heat to electricity and are of great interest in waste heat recovery, solid-state cooling and so on. Here we assessed the potential of SnS2 and SnSe2 as thermoelectric materials at the temperature gradient from 300 to 800 K. Reflecting the crystal structure, the transport coefficients are highly anisotropic between a and c directions, in particular for the electrical conductivity. The preferred direction for both materials is the a direction in TE application. Most strikingly, when 800 K is reached, SnS2 can show a peak power factor (PF) of 15.50 ?W cm(-1) K(-2) along the a direction, while a relatively low value (11.72 ?W cm(-1) K(-2)) is obtained in the same direction of SnSe2. These values are comparable to those observed in thermoelectrics such as SnSe and SnS. At 300 K, the minimum lattice thermal conductivity (?min) along the a direction is estimated to be about 0.67 and 0.55 W m(-1) K(-1) for SnS2 and SnSe2, respectively, even lower than the measured lattice thermal conductivity of Bi2Te3 (1.28 W m(-1) K(-1) at 300 K). The reasonable PF and ?min suggest that both SnS2 and SnSe2 are potential thermoelectric materials. Indeed, the estimated peak ZT can approach 0.88 for SnSe2 and a higher value of 0.96 for SnS2 along the a direction at a carrier concentration of 1.94 × 10(19) (SnSe2) vs. 2.87 × 10(19) cm(-3) (SnS2). The best ZT values in SnX2 (X = S, Se) are comparable to that in Bi2Te3 (0.8), a typical thermoelectric material. We hope that this theoretical investigation will provide useful information for further experimental and theoretical studies on optimizing the thermoelectric properties of SnX2 materials. PMID:26486877

  9. Analisa Teknis dan Ekonomis Penggunaan ICCP (Impressed Current Cathodic Protection Dibandingkan dengan Sacrificial Anode dalam Proses Pencegahan Korosi

    Directory of Open Access Journals (Sweden)

    Afif Wiludin

    2013-03-01

    Full Text Available Perlindungan badan kapal  terhadap korosi dengan  menggunakan  metode perlindungan katodik pada prinsipnya adalah sel elektrokimia untuk mengendalikan korosi dengan mengkonsentrasikan reaksi oksigen pada sel galvanik dan menekan korosi pada katoda dalam sel yang sama. Pada proteksi katodik, logam yang akan dilindungi dijadikan katoda dan reaksi oksidasi terjadi di anoda. Ada dua macam cathodic protection yaitu Sacrificial Anode Cathodic Protection (SACP dan Impressed Current Cathodic Protection (ICCP. Dilakukan penelitian tentang analisa teknis dan ekonomis penggunaan ICCP dibandingkan dengan SACP dalam proses pencegahan korosi, kedua sistem dibandingkan dalam jangka 20 tahun, dari segi teknis dengan menggunakan perbandingan perhitungan sesuai standar DnV, yang dibandingkan dari tahap design, tahap instalasi, dan maintenance, dari segi ekonomis perbandingan dibedakan dari tahap pengadaan komponen-komponen sistem, tahap instalasi, dan tahap maintenance. Data perbandingan diperoleh dengan perhitungan sesuai standar, study literature, diskusi dan interview. Hasil perhitungan perbandingan yang diperkirakan selama 20 tahun, dari segi teknis kedua sistem memenuhi standar yang berdasar pada sistem perhitungan standar DnV B-401, sedangkan dari segi ekonomis, biaya untuk sistem ICCP sebesar Rp. 205.405.000,00 dan sistem SACP sebesar Rp. 562.590.000,00, sehingga lebih ekonomis menggunakan sistem ICCP sebesar Rp 357.185.000, 00 atau 63,49% dari biaya untuk sistem SACP

  10. Effect of zinc sacrificial anode degradation on the defence system of the Pacific oyster, Crassostrea gigas: chronic and acute exposures.

    Science.gov (United States)

    Mottin, Elmina; Caplat, Christelle; Latire, Thomas; Mottier, Antoine; Mahaut, Marie-Laure; Costil, Katherine; Barillier, Daniel; Lebel, Jean-Marc; Serpentini, Antoine

    2012-09-01

    Two types of exposures were performed to assess the effects of zinc released from sacrificial anode degradation: a chronic exposure, in which oysters were exposed to 0.53±0.04 mg Zn L(-1) for 10 weeks, and an acute exposure, where oysters were exposed to 10.2±1.2 mg Zn L(-1) for 1 week. At the end of the acute exposure experiment, 81.8% mortality was recorded. In contrast, no mortality was detected after 10 weeks exposure. Moreover, all of the immune system biomarkers studied, except the number of circulating haemocytes, were stimulated by a moderate level of zinc and inhibited by a high level. Our exposure conditions did not induce SOD or MXR mRNA expression in gills and digestive gland. However, an increase of MT mRNA is observed in these tissues. The results indicate that oysters are sensitive to acute zinc toxicity but are only moderately affected by a mild zinc concentration. PMID:22770699

  11. A new route toward ultrasensitive, flexible chemical sensors: metal nanotubes by wet-chemical synthesis along sacrificial nanowire templates.

    Science.gov (United States)

    Lim, Mi Ae; Kim, Dong Hwan; Park, Chong-Ook; Lee, Young Wook; Han, Sang Woo; Li, Zhiyong; Williams, R Stan; Park, Inkyu

    2012-01-24

    We developed a novel low-temperature, wet-chemical process for the facile synthesis of metal nanotube arrays through the reduction of metal precursors along sacrificial metal oxide nanowire templates and demonstrated its applications to the ultrasensitive, low-power, mechanically robust, and flexible chemical sensors. The in situ dissolution of ZnO nanowire templates, which were hydrothermally grown on electrode surfaces, during the reaction allows the direct formation of tubular Pd nanostructures on the sensor devices without the need of complex processes for device integration or template removal. Moreover, this simple synthesis was carried out at low-temperature with mild chemical conditions; therefore we could make Pd nanotube devices not only on silicon substrates but also on flexible polymer substrates. The H(2) sensing of such Pd nanotube devices was investigated under various mechanical loading and showed excellent reliability and robustness. The sensitivity of our devices was found to be at least 2 orders of magnitude higher than literature values for H(2) sensors, which can be attributed to the high surface area and the well-formed interconnect of Pd tubular nanostructures in our devices. PMID:22148522

  12. Highly alloyed PtRu black electrocatalysts for methanol oxidation prepared using magnesia nanoparticles as sacrificial templates

    Science.gov (United States)

    Zou, Liangliang; Guo, Jing; Liu, Juanying; Zou, Zhiqing; Akins, Daniel L.; Yang, Hui

    2014-02-01

    Synthesis of small particle size, highly alloyed PtRu black catalysts for application in direct methanol fuel cells remains a substantial challenge. In this work, PtRu (1:1) black catalysts have been synthesized using Pt carbonyl complex and RuCl3 as initial precursors and magnesia nanoparticles as sacrificial templates. Magnesia is used to prevent the aggregation of synthesized PtRu nanoparticles during heat treatment, and thus promoting the controllable formation of PtRu black of high alloy composition and small particle size. X-ray diffraction shows that the PtRu black nanoparticles have a single-phase face-centered cubic structure and that the degree of alloying increases with treatment temperature. The mean particle size of the PtRu black catalysts, after heat-treatment from 250 to 300 °C, is found to be ca. 3 nm, only slightly larger than that of commercial Johnson-Matthey PtRu black, but more highly alloyed. Electrochemical measurements indicate that the catalytic activity for methanol oxidation on in-house prepared PtRu black catalysts is about twice that of the commercial product, with greater durability, indicating that the degree of alloying between Pt and Ru plays an important role in improving both catalytic activity and durability of the catalysts when used for methanol oxidation.

  13. Preparation of ZnO Nanoparticles and Photocatalytic H2 Production Activity from Different Sacrificial Reagent Solutions

    Science.gov (United States)

    Peng, Tian-you; Lv, Hong-jin; Zeng, Peng; Zhang, Xiao-hu

    2011-08-01

    ZnO nanoparticles were synthesized via a direct precipitation method followed by a heterogeneous azeotropic distillation and calcination processes, and then characterized by X-ray power diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption measurement. The effects of Pt-loading amount, calcination temperature, and sacrificial reagents on the photocatalytic H2 evolution efficiency from the present ZnO suspension were investigated. The experimental results indicate that ZnO nanoparticles calcined at 400 °C exhibit the best photoactivity for the H2 production in comparison with the samples calcined at 300 and 500 °C, and the photocatalytic H2 production efficiency from a methanol solution is much higher than that from a triethanolamine solution. It can be ascribed to the oxidization of methanol also contributes to the H2 production during the photochemical reaction process. Moreover, the photocatalytic mechanism for the H2 production from the present ZnO suspension system containing methanol solution is also discussed in detail.

  14. Fully integrated and encapsulated micro-fabricated vacuum diode and method of manufacturing same

    Energy Technology Data Exchange (ETDEWEB)

    Resnick, Paul J.; Langlois, Eric

    2015-12-01

    Disclosed is an encapsulated micro-diode and a method for producing same. The method comprises forming a plurality columns in the substrate with a respective tip disposed at a first end of the column, the tip defining a cathode of the diode; disposing a sacrificial oxide layer on the substrate, plurality of columns and respective tips; forming respective trenches in the sacrificial oxide layer around the columns; forming an opening in the sacrificial oxide layer to expose a portion of the tips; depositing a conductive material in of the opening and on a surface of the substrate to form an anode of the diode; and removing the sacrificial oxide layer.

  15. Synthesis of highly dispersed ferromagnetic materials based on layered lithium aluminum hydroxides and nickel and cobalt particles

    International Nuclear Information System (INIS)

    The reaction between a concentrated aqueous lithium nitrate solution and a cobalt-containing composite prepared through the thermal decomposition of [LiAl2(OH)6]2[CoEDTA] · 4H2O in vacuum at temperatures from 400 to 500 deg C has been studied by X-ray diffraction and chemical analysis. The results indicate that, first, the lithium aluminum oxide species present in the composite react with water molecules in the lithium nitrate solution to form layered Li-Al hydroxides. The next step is a hydroxide for nitrate ion exchange leading to the formation of a nitrate form of the hydroxides. A similar mechanism underlies the formation of a nitrate in the reaction between nickel-containing composites and aqueous lithium nitrate. The nickel-and cobalt-containing composites prepared via vacuum thermolysis of [LiAl2(OH)6]2[M EDTA] · 4H2O (M = Ni, Co) react with water to form a ferromagnetic carrier containing, in addition to a metallic phase, an aluminum lithium hydroxide and bayerite impurity

  16. Molecular layer deposition of "titanicone", a titanium-based hybrid material, as an electrode for lithium-ion batteries.

    Science.gov (United States)

    Van de Kerckhove, Kevin; Mattelaer, Felix; Deduytsche, Davy; Vereecken, Philippe M; Dendooven, Jolien; Detavernier, Christophe

    2016-01-01

    Molecular layer deposition (MLD) of hybrid organic-inorganic thin films called "titanicones" was achieved using tetrakisdimethylaminotitanium (TDMAT) and glycerol (GL) or ethylene glycol (EG) as precursors. For EG, in situ ellipsometry revealed that the film growth initiates, but terminates after only 5 to 10 cycles, probably because both hydroxyls react with the surface. GL has a third hydroxyl group, and in that case steady state growth could be achieved. The GL process displayed self-limiting reactions for both reactants in the temperature range from 80 °C to 160 °C, with growth rates of 0.9 to 0.2 Å per cycle, respectively. Infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the hybrid nature of the films, with a carbon atomic concentration of about 20%. From X-ray reflectivity, the density was estimated at 2.2 g cm(-3). A series of films was subjected to water etching and annealing under air or He atmosphere at 500 °C. The carbon content of the films was monitored with FTIR and XPS. Almost all carbon was removed from the air annealed and water treated films. The He annealed samples however retained their carbon content. Ellipsometric porosimetry (EP) showed 20% porosity in the water etched samples, but no porosity in the annealed samples. Electrochemical measurements revealed lithium ion activity during cyclic voltammetry in all treated films, while the as-deposited film was inactive. With increasing charge current, the He annealed samples outperformed amorphous and anatase TiO2 references in terms of capacity retention. PMID:26662179

  17. High spatial resolution mapping of deposition layers on plasma facing materials by laser ablation microprobe time-of-flight mass spectroscopy

    International Nuclear Information System (INIS)

    A laser ablation microprobe time-of-flight mass spectroscopy (LAM-TOF-MS) system with high spatial resolution, ?20 nm in depth and ?500 ?m or better on the surface, is developed to analyze the composition distributions of deposition layers on the first wall materials or first mirrors in tokamak. The LAM-TOF-MS system consists of a laser ablation microprobe combined with a TOF-MS and a data acquisition system based on a LabVIEW program software package. Laser induced ablation combined with TOF-MS is an attractive method to analyze the depth profile of deposited layer with successive laser shots, therefore, it can provide information for composition reconstruction of the plasma wall interaction process. In this work, we demonstrate that the LAM-TOF-MS system is capable of characterizing the depth profile as well as mapping 2D composition of deposited film on the molybdenum first mirror retrieved from HL-2A tokamak, with particular emphasis on some of the species produced during the ablation process. The presented LAM-TOF-MS system provides not only the 3D characterization of deposition but also the removal efficiency of species of concern

  18. High spatial resolution mapping of deposition layers on plasma facing materials by laser ablation microprobe time-of-flight mass spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Qingmei; Li, Cong; Hai, Ran; Zhang, Lei; Feng, Chunlei; Ding, Hongbin, E-mail: hding@dlut.edu.cn [School of Physics and Optical Electronic Technology, Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Chinese Ministry of Education, Dalian University of Technology, Dalian 116024 (China); Zhou, Yan; Yan, Longwen; Duan, Xuru [Southwestern Institute of Physics, P.O. Box 432, No. 3 South Section 3, Circle Road 2, Chengdu 610041, Sichuan (China)

    2014-05-15

    A laser ablation microprobe time-of-flight mass spectroscopy (LAM-TOF-MS) system with high spatial resolution, ?20 nm in depth and ?500 ?m or better on the surface, is developed to analyze the composition distributions of deposition layers on the first wall materials or first mirrors in tokamak. The LAM-TOF-MS system consists of a laser ablation microprobe combined with a TOF-MS and a data acquisition system based on a LabVIEW program software package. Laser induced ablation combined with TOF-MS is an attractive method to analyze the depth profile of deposited layer with successive laser shots, therefore, it can provide information for composition reconstruction of the plasma wall interaction process. In this work, we demonstrate that the LAM-TOF-MS system is capable of characterizing the depth profile as well as mapping 2D composition of deposited film on the molybdenum first mirror retrieved from HL-2A tokamak, with particular emphasis on some of the species produced during the ablation process. The presented LAM-TOF-MS system provides not only the 3D characterization of deposition but also the removal efficiency of species of concern.

  19. Artificial layered perovskite oxides A(B0.5B?0.5)O3 as potential solar energy conversion materials

    International Nuclear Information System (INIS)

    Perovskite oxides with a d0 electronic configuration are promising photocatalysts and exhibit high electron mobilities. However, their band gaps are too large for efficient solar energy conversion. On the other hand, transition metal cations with partially filled dn electronic configurations give rise to visible light absorption. In this study, by using hybrid density functional theory calculations, it is demonstrated that the virtues of the two categories of materials can be combined in perovskite oxide A(B0.5B?0.5)O3 with a layered B-site ordering along the [001] direction. The electronic structures of the four selected perovskite oxide compounds, La(Ti0.5Ni0.5)O3, La(Ti0.5Zn0.5)O3, Sr(Nb0.5Cr0.5)O3, and Sr(Nb0.5Fe0.5)O3 are calculated and discussed

  20. High density fluorocarbon plasma etching of methylsilsesquioxane SiOC(H) low-k material and SiC(H) etch stop layer: surface analyses and investigation of etch mechanisms

    International Nuclear Information System (INIS)

    This paper focuses on plasma etching and XPS surface analyses of new dielectric materials used in integrated circuits. We investigate by XPS surface modifications of methylsilsesquioxane low-k polymer (SiOC(H)) and amorphous hydrogenated silicon carbide (SiC(H)) when exposed to Ar, SF6 and C2F6-based high density plasmas. Ar and SF6 plasmas remove the carbonaceous groups from the surface leading to the formation of fluorinated top layers (SiOF and SiF-like layers) in SF6 plasma. In the case of C2F6-based mixtures, the surface structure fits well with a two-layer model, consisting of a fluorocarbon top layer above a fluorinated interaction layer (SiOF or SiF) on the bulk materials (SiOC(H) or SiC(H)). Determination of top layer thicknesses from XPS data is discussed. We show that material etch rate is not correlated with the total modified thickness, in contrast to the top fluorocarbon layer thickness which is in good correlation with etch rates. Etch yields (etch rates divided by the ion flux) are calculated and are studied in order to draw material etch mechanisms in C2F6 based mixtures. We conclude that for both materials, etching mechanisms in C2F6/H2 mixtures, and to a lesser extent in C2F6/Ar mixtures, are close to those of silicon in fluorocarbon plasmas and different from those of the conventional interlevel dielectric material SiO2. On the contrary etching mechanisms in C2F6/O2 mixtures are similar to those of silicon dioxide in fluorocarbon plasmas

  1. Supracolloidal Assemblies as Sacrificial Templates for Porous Silk-Based Biomaterials

    Directory of Open Access Journals (Sweden)

    John G. Hardy

    2015-08-01

    Full Text Available Tissues in the body are hierarchically structured composite materials with tissue-specific properties. Urea self-assembles via hydrogen bonding interactions into crystalline supracolloidal assemblies that can be used to impart macroscopic pores to polymer-based tissue scaffolds. In this communication, we explain the solvent interactions governing the solubility of urea and thereby the scope of compatible polymers. We also highlight the role of solvent interactions on the morphology of the resulting supracolloidal crystals. We elucidate the role of polymer-urea interactions on the morphology of the pores in the resulting biomaterials. Finally, we demonstrate that it is possible to use our urea templating methodology to prepare Bombyx mori silk protein-based biomaterials with pores that human dermal fibroblasts respond to by aligning with the long axis of the pores. This methodology has potential for application in a variety of different tissue engineering niches in which cell alignment is observed, including skin, bone, muscle and nerve.

  2. Synthesis and structural characterization of zirconium phosphate adipate dimethyl sulphoxide: A new lambda-type organic-inorganic layered material

    Indian Academy of Sciences (India)

    Hussein Alhendawi

    2014-07-01

    ?Zirconium phosphate adipate dimethyl sulphoxide, -ZrPO4(OOC-(CH2)4-COOH)(CH3)2SO, is prepared by means of topotactic anion exchange of the chloride ligand of -Zirconium phosphate, -ZrPO4Cl(CH3)2SO, with adipate. The samples are characterized by thermal analyses, X-ray diffractometry and FT-IR spectrophotometry. The used analysis approaches provide strong evidence that the chloride monovalent anions of -Zirconium phosphate are completely exchanged with the carboxylate groups of the adipate monoanionic ligands. Moreover, the adipate ligands replace the chloride anions in a 1:1 stoichiometry. In this case the formula of the derivative should contain the monoanionic adipate fragment: (OOC-(CH2)4-COOH). This formula is in agreement with TGA and elemental analysis. With respect to intercalation properties, the synthesized adipate-solid phase has a higher acidic character and a larger gallery height in comparison to the pristine -Zirconium phosphate (1.47, 1.02 nm, respectively). Therefore, this material is expected to be a suitable host for intercalation of huge basic guests.

  3. Analytical extraction of residual stresses and gradients in MEMS structures with application to CMOS-layered materials

    Science.gov (United States)

    Fachin, F.; Nikles, S. A.; Dugundji, J.; Wardle, B. L.

    2011-09-01

    Accurate thin-film characterization is a key requirement in the MEMS industry. Residual stresses determine both the final shape and the functionality of released micromachined structures, and should therefore be accurately assessed. To date, a number of techniques to characterize thin-film materials have been developed, from substrate curvature measurement to methods that exploit the post-release deformation of test structures. These techniques have some major drawbacks, from high implementation costs to accuracy limitations due to improper boundary condition modeling. Here, we present a new technique for the characterization of multilayered, composite MEMS structures that uses easily accessible experimental information on the post-release deformation of microbridges only, with no need for multiple beam lengths. The method is based on an analytical solution of the (post-)buckling problem of microbridges, including the effect of residual stresses (both mean and gradient) and non-ideal clamping (boundary flexibility). The method allows simultaneous characterization of both the mean and the gradient residual stress components, as well as the effective boundary condition associated with the fabrication process, yielding approximately one order of magnitude improvement in resolution compared to extant methods using the same type and number of test structures. The higher resolution is largely attributable to proper accounting for boundary flexibility by our method, with the boundary condition for the structures in this work being ~90% as stiff in bending relative to the commonly assumed perfectly clamped condition. Additional enhancement can be achieved with post-release deformation measurements of simple cantilevers in addition to the microbridges. The method is useful as it ensures very low stress extraction uncertainty using a limited number of microbridge test structures, and it is transferrable to package-stress characterization. The analytical approach can also be extended to device design, quantifying the effect of residual stresses and boundary flexibility on a structure's post-release state.

  4. In Situ Growth of a Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications

    Science.gov (United States)

    Nesbitt, James A.; Opila, Elizabeth J.; Nathal, Michael V.

    2012-06-01

    The compound Yb14MnSb11 is a p-type thermoelectric material of interest to the National Aeronautics and Space Administration (NASA) as a candidate replacement for the state-of-the-art Si-Ge used in current radioisotope thermoelectric generators (RTGs). Ideally, the hot end of this leg would operate at 1000°C in the vacuum of space. Although Yb14MnSb11 shows the potential to double the value of the thermoelectric figure of merit ( zT) over that of Si-Ge at 1000°C, it suffers from a high sublimation rate at elevated temperatures and would require a coating in order to survive the required RTG lifetime of 14 years. The purpose of the present work is to measure the sublimation rate of Yb14MnSb11 and to investigate sublimation suppression for this material. This paper reports on the sublimation rate of Yb14MnSb11 at 1000°C (˜3 × 10-3 g/cm2 h) and efforts to reduce the sublimation rate with an in situ grown Yb2O3 layer. Despite the success in forming thin, dense, continuous, and adherent oxide scales on Yb14MnSb11, the scales did not prove to be sublimation barriers.

  5. In-Situ Growth of Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications

    Science.gov (United States)

    Nesbitt, James A.; Opila, Elizabeth J.; Nathal, Michael V.

    2012-01-01

    The compound Yb14MnSb11 is a p-type thermoelectric material of interest to the National Aeronautics and Space Administration (NASA) as a candidate replacement for the state-of-the-art Si-Ge used in current radioisotope thermoelectric generators (RTGs). Ideally, the hot end of this leg would operate at 1000 C in the vacuum of space. Although Yb14MnSb11 shows the potential to double the value of the thermoelectric figure of merit (zT) over that of Si-Ge at 1000 C, it suffers from a high sublimation rate at elevated temperatures and would require a coating in order to survive the required RTG lifetime of 14 years. The purpose of the present work is to measure the sublimation rate of Yb14MnSb11 and to investigate sublimation suppression for this material. This paper reports on the sublimation rate of Yb14MnSb11 at 1000 C (approximately 3 x 10(exp -3) grams per square centimeter hour) and efforts to reduce the sublimation rate with an in situ grown Yb2O3 layer. Despite the success in forming thin, dense, continuous, and adherent oxide scales on Yb14MnSb11, the scales did not prove to be sublimation barriers.

  6. Experimental study of Homogen Process for lead-type multi layer cask and applicability of R-PUF for shock absorbing material

    International Nuclear Information System (INIS)

    Since we developed and manufactured the first domestic casks, we have accumulated significant amount of technology on casks. Lead-Type Multi Layer Cask is one of our major products. One of the processes to make this cask is to treat Homogen Process on the inside surfaces of cask shell for keeping thermal conductivity performance. To confirm this performance quantitatively, we carried out experiment of heat conduction using a specimen assumed body of real cask. Approximation formulas of thermal resistances were derived. The model of actual cask was calculated concerning thermal conductivity with the approximations. As the results, we confirmed there is no problem of thermal conductivity of the actual cask. We have developed new shock absorber with new material as well. To confirm its performance, we carried out drop test and heating test assuming real cask. In drop test, model cask was fallen down from nine meter height. In heating test, specimens were heated for 30 minutes in 800degC atmosphere. We confirmed the material has good performances for shock absorbing, thermal insulation and flame resistance. All of the results, we confirmed the effect of Homogen Process and the possibility of new shock absorber are effective for our cask designs. (author)

  7. Role of lysine during protein modification by HOCl and HOBr: halogen-transfer agent or sacrificial antioxidant?

    Science.gov (United States)

    Sivey, John D; Howell, Stanley C; Bean, Doyle J; McCurry, Daniel L; Mitch, William A; Wilson, Corey J

    2013-02-19

    Although protein degradation by neutrophil-derived hypochlorous acid (HOCl) and eosinophil-derived hypobromous acid (HOBr) can contribute to the inactivation of pathogens, collateral damage to host proteins can also occur and has been associated with inflammatory diseases ranging from arthritis to atherosclerosis. Though previous research suggested halotyrosines as biomarkers of protein damage and lysine as a mediator of the transfer of a halogen to tyrosine, these reactions within whole proteins are poorly understood. Herein, reactions of HOCl and HOBr with three well-characterized proteins [adenylate kinase (ADK), ribose binding protein, and bovine serum albumin] were characterized. Three assessments of oxidative modifications were evaluated for each of the proteins: (1) covalent modification of electron-rich amino acids (assessed via liquid chromatography and tandem mass spectrometry), (2) attenuation of secondary structure (via circular dichroism), and (3) fragmentation of protein backbones (via sodium dodecyl sulfate-polyacrylamide gel electrophoresis). In addition to forming halotyrosines, HOCl and HOBr converted lysine into lysine nitrile (2-amino-5-cyanopentanoic acid), a relatively stable and largely overlooked product, in yields of up to 80%. At uniform oxidant levels, fragmentation and loss of secondary structure correlated with protein size. To further examine the role of lysine, a lysine-free ADK variant was rationally designed. The absence of lysine increased yields of chlorinated tyrosines and decreased yields of brominated tyrosines following treatments with HOCl and HOBr, respectively, without influencing the susceptibility of ADK to HOX-mediated losses of secondary structure. These findings suggest that lysine serves predominantly as a sacrificial antioxidant (via formation of lysine nitrile) toward HOCl and as a halogen-transfer mediator [via reactions involving ?-N-(di)haloamines] with HOBr. PMID:23327477

  8. Performance of the sacrificial galvanic anodes in rehabilitation of marine structure at port Blair, Andaman and Nichobar islands, India

    Directory of Open Access Journals (Sweden)

    V. Rajendran

    2011-05-01

    Full Text Available In recent years, more and more focus has been shifting towards repair and rehabilitation of deficient concrete infrastructures rather than replacement, either in full or replacing the structural members. While carrying out the rehabilitation, one should keep in mind that the methodology should have cost effective strategy and durability. The deterioration caused by the corrosion of reinforcing steel in concrete structures has been recognized as one of the greatest maintenance challenges being faced by many government agencies and other private owners including the engineering contracting companies in the filed of construction industry today. Technological advances have created a wide range of new product and systems which claim to provide long-lasting protection and serviceability for these structures. However, in order to effectively address the problem it is essential to first understand the cause of the corrosion. The paper describes in detail the philosophy of the corrosion and to evaluate the effect of having anodes installed in the concrete members. The paper also describes in detail investigations conducted on a corrosion damaged jetty approach portion, the repair methodology suggested for the rehabilitation of the structure and executed. The repair methodology proposed included the provision of galvanic anodes. The data presented on the monitoring of the repaired jetty through half cell potential test conducted over a period of one year from the time of completion of the repair to assess the effectiveness of the sacrificial anodes. The investigations have clearly demonstrated that galvanic anodes have proved to be an effective corrosion control technique for reinforced concrete structures.

  9. Multi-Instrument Characterization of the Surfaces and Materials in Microfabricated, Carbon Nanotube-Templated Thin Layer Chromatography Plates. An Analogy to ‘The Blind Men and the Elephant’

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, David S.; Kanyal, Supriya S.; Madaan, Nitesh; Hancock, Jared M.; Dadson, Andrew; Vail, Michael A.; Vanfleet, Richard; Shutthanandan, V.; Zhu, Zihua; Engelhard, Mark H.; Linford, Matthew R.

    2013-08-08

    Herein we apply a suite of surface/materials analytical tools to characterize some of the materials created in the production of microfabricated thin layer chromatography plates. Techniques used include X-ray photoelectron spectroscopy (XPS), valence band spectroscopy, static time-of-flight secondary ion spectrometry (ToF-SIMS) in both positive and negative ion modes, Rutherford backscattering spectroscopy (RBS), and helium ion microscopy (HIM). Materials characterized include: the Si(100) substrate with native oxide: Si/SiO2, alumina (35 nm) deposited as a diffusion barrier on the Si/SiO2: Si/SiO2/Al2O3, iron (6 nm) thermally evaporated on the Al2O3: Si/SiO2/Al2O3/Fe, the iron film annealed in H2 to make Fe catalyst nanoparticles: Si/SiO2/Al2O3/Fe(NP), and carbon nanotubes (CNTs) grown from the Fe nanoparticles: Si/SiO2/Al2O3/Fe(NP)/CNT. The Fe thin films and nanoparticles are found in an oxidized state. Some of the analyses of the CNTs/CNT forests reported appear to be unique: the CNT forest appears to exhibit an interesting ‘channeling’ phenomenon by RBS, we observe an odd-even effect in the ToF-SIMS spectra of Cn- species for n = 1 – 6, with ions at even n showing greater intensity than the neighboring signals, and ions with n ? 6 showing a steady decrease in intensity, and valence band characterization of CNTs using X-radiation is reported. The information obtained from the combination of the different analytical tools provides a more complete understanding of our materials than a single technique, which is analogous to the story of ‘The Blind Men and the Elephant’. (Of course there is increasing emphasis on the use of multiple characterization tools in surface and materials analysis.) The raw XPS and ToF-SIMS spectra from this study will be submitted to Surface Science Spectra for archiving.

  10. Laboratory simulation showing the influence of salt efflorescence on the weathering of composite building materials

    Science.gov (United States)

    Cultrone, G.; Sebastián, E.

    2008-12-01

    A common decay scenario in old and new buildings was simulated: the effects on masonry structures of salt efflorescence or subefflorescence produced by the rise of saline solution. Eight different types of masonry wall each made up of a combination of different construction materials (brick, calcarenite and four types of mortar were combined as follows: pure lime mortar, mortar + air entraining agent, mortar + pozzolana, mortar + air entraining agent + pozzolana) have been tested. These materials have different textures (strong anisotropy in brick, irregular-shaped pores in calcarenite, retraction fissures or rounded pores in mortars which also show a reduction of porosity along the contact area with the stone), different hydric behaviours (under total immersion brick + mortar specimens absorb water faster than calcarenite + mortar specimens) and different pore size distribution (brick shows unimodal pore distribution, whereas calcarenite and mortars are bimodal). In the salt weathering test, mortars interlayered with masonry blocks did not act as sacrificial layers. In fact, they allowed salts to rise through them and crystallize on the brick or calcarenite pieces causing the masonry structure to decay. Only the addition of an air-entraining agent partially hindered the capillary rise of the salt-laden solutions.

  11. Designed Single-Step Synthesis, Structure, and Derivative Textural Properties of Well-Ordered Layered Penta-coordinate Silicon Alcoholate Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Li, XS; Michaelis, VK; Ong, TC; Smith, SJ; Griffin, RG; Wang, EN

    2014-04-15

    The controllable synthesis of well-ordered layered materials with specific nanoarchitecture poses a grand challenge in materials chemistry. Here the solvothermal synthesis of two structurally analogous 5-coordinate organosilicate complexes through a novel transesterification mechanism is reported. Since the polycrystalline nature of the intrinsic hypervalent Si complex thwarts the endeavor in determining its structure, a novel strategy concerning the elegant addition of a small fraction of B species as an effective crystal growth mediator and a sacrificial agent is proposed to directly prepare diffraction-quality single crystals without disrupting the intrinsic elemental type. In the determined crystal structure, two monomeric primary building units (PBUs) self-assemble into a dimeric asymmetric secondary BU via strong Na+O2- ionic bonds. The designed one-pot synthesis is straightforward, robust, and efficient, leading to a well-ordered (10)-parallel layered Si complex with its principal interlayers intercalated with extensive van der Waals gaps in spite of the presence of substantial Na+ counter-ions as a result of unique atomic arrangement in its structure. However, upon fast pyrolysis, followed by acid leaching, both complexes are converted into two SiO2 composites bearing BET surface areas of 163.3 and 254.7m(2)g(-1) for the pyrolyzed intrinsic and B-assisted Si complexes, respectively. The transesterification methodology merely involving alcoholysis but without any hydrolysis side reaction is designed to have generalized applicability for use in synthesizing new layered metal-organic compounds with tailored PBUs and corresponding metal oxide particles with hierarchical porosity.

  12. Functionalization of layered titanates.

    Science.gov (United States)

    Ide, Yusuke; Sadakane, Masahiro; Sano, Tsuneji; Ogawa, Makoto

    2014-03-01

    This review article describes the synthesis, modification, and function of lepidocrocite-type layered titanate (A(x)Ti(2-y)M(y)O4, A: A, interlayer cation; M, metal or vacancy). Due to the compositional variation, which affects cation exchange, semiconducting and swelling properties, lepidocrocite-type layered titanates have attracted increasing attention in solid-state materials chemistry. The immobilization of functional units has been done to improve the properties as well as to impart additional functions. Here, we highlight recent developments of hybrid materials derived from the intercalation of inorganic and organic cations, organic functional groups, and nanoparticles into lepidocrocite-type layered titanates. PMID:24745207

  13. Absorber material cladding chemical interaction in vented fast breeder reactor absorber pins. B 4C/stainless steel chemical interaction in sodium environment and effect of metallic Nb and Cr 4 layers

    Science.gov (United States)

    Heuvel, Hans-Jochen; Höller, Peter; Donner, Philipp

    1985-02-01

    Out-of-pile tests were performed to study the chemical interaction between B 4C and cladding material (stainless steel) in sodium environment as components of a "Fast Breeder" absorber pin. The results of isothermal capsule tests (873-1073 K and 750-8600 h) show a chemical attack on the cladding. The penetration depth amounted to 50 microns within one year at 873 K and increased parabolically in the course of time. The test results indicate that diffusion of boron through the reaction layer is determinative for the kinetics of chemical interaction. Carbon diffusion is inhibited by the formation of metal boride layers. Metallic niobium or chromium layers on the inner surface of the cladding material reduce definitely the process of boronation. The tests show that chemical interaction in the B 4C-Na-stainless steel system is sufficient low at conditions foreseen for high absorber pins in SNR-300 reloads and SNR-2.

  14. Young's modulus and density measurements of thin atomic layer deposited films using resonant nanomechanics

    Science.gov (United States)

    Ilic, B.; Krylov, S.; Craighead, H. G.

    2010-08-01

    Material properties of atomic layer deposited (ALD) thin films are of interest for applications ranging from wear resistance to high-k dielectrics in electronic circuits. We demonstrate the ability to simultaneously measure Young's modulus (E) and density (?) of 21.2-21.5 nm ALD hafnia, alumina, and aluminum nitride ultrathin films by observing vibrations of nanomechanical cantilever beams. The nanomechanical structures were fabricated from a 250 nm thick single crystal silicon layer with varying length and width ranging from 6 ?m to 10 ?m and 45 nm to 1 ?m, respectively. Our approach is based on an optical excitation and interferometric detection of in-plane and out-of plane vibrational spectra of single crystal silicon cantilevers before and after a conformal coating deposition of an ALD thin film. In conjunction with three-dimensional numerical finite element analysis, measurements of resonance carried out prior to the ALD revealed that while the influence of clamping compliance arising from the undercut of the sacrificial layer is significant for wider beams, the effect is less pronounced for both, narrower cantilevers and the in-plane vibrational response. Following the deposition, higher stiffness alumina films (E >ESi) showed an increase in the resonant frequency whereas lower stiffness (E frequency. From the measured spectral response, material properties were extracted using simple expressions for E and ? in terms of measured in-plane and out-of-plane frequencies shifts. The derived model was based on an ideally clamped Euler-Bernoulli beam with effective bending stiffness and effective mass per unit length. In-plane and out-of-plane frequency measurements provided two equations that enabled simultaneous extraction of E and ?. Three-dimensional finite element analysis showed that residual stress, nonideal clamping conditions, and the mismatch in the Poisson's ratio between the deposited film and the nanomechanical oscillator have minor influence on the determined material properties. Experimental results obtained for the measured films were in excellent agreement with finite element simulations incorporating the geometric undercut caused by release of the suspended structures.

  15. A novel radial anode layer ion source for inner wall pipe coating and materials modification--hydrogenated diamond-like carbon coatings from butane gas.

    Science.gov (United States)

    Murmu, Peter P; Markwitz, Andreas; Suschke, Konrad; Futter, John

    2014-08-01

    We report a new ion source development for inner wall pipe coating and materials modification. The ion source deposits coatings simultaneously in a 360° radial geometry and can be used to coat inner walls of pipelines by simply moving the ion source in the pipe. Rotating parts are not required, making the source ideal for rough environments and minimizing maintenance and replacements of parts. First results are reported for diamond-like carbon (DLC) coatings on Si and stainless steel substrates deposited using a novel 360° ion source design. The ion source operates with permanent magnets and uses a single power supply for the anode voltage and ion acceleration up to 10 kV. Butane (C4H10) gas is used to coat the inner wall of pipes with smooth and homogeneous DLC coatings with thicknesses up to 5 ?m in a short time using a deposition rate of 70 ± 10 nm min(-1). Rutherford backscattering spectrometry results showed that DLC coatings contain hydrogen up to 30 ± 3% indicating deposition of hydrogenated DLC (a-C:H) coatings. Coatings with good adhesion are achieved when using a multiple energy implantation regime. Raman spectroscopy results suggest slightly larger disordered DLC layers when using low ion energy, indicating higher sp(3) bonds in DLC coatings. The results show that commercially interesting coatings can be achieved in short time. PMID:25173323

  16. Effect of electronic state of ions on the electrochemical properties of layered cathode materials LiNi1-2xCoxMnxO2

    International Nuclear Information System (INIS)

    Cathode materials of the composition LiNi1-2xCoxMnxO2 (x = 0.1; 0.2; 0.33) synthesized from the Ni, Co, Mn mixed hydroxides and LiOH by using mechanical activation method are studied. It is shown that all the synthesized compounds have layered structure described by the space group R-3m. A decrease in nickel content entails a decrease in the cell volume and degree of the structure disordering. According to X-ray photoelectron spectroscopy data, the electronic main state of d-block ions on the surface of the prepared samples corresponds to Ni2+, Co3+, and Mn4+. An increase in the nickel content leads to the increase in the Ni2p3/2 and Co2p3/2 binding energy, which suggests a change in the Me-O bond covalence. According to magnetic susceptibility measurement data, nickel ions in LiNi0.6Co0.2Mn0.2O2 exist in the two oxidation states: Ni2+ and Ni3+. It is shown that this sample features the highest specific discharge capacity (?170 mAh/g). The positions of redox peaks in the differential capacitance curves depend on the sample composition, i.e. increase in nickel content gives rise to their shifting towards lower voltages

  17. The performance of La0.6Sr1.4MnO4 layered perovskite electrode material for intermediate temperature symmetrical solid oxide fuel cells

    Science.gov (United States)

    Zhou, Jun; Chen, Gang; Wu, Kai; Cheng, Yonghong

    2014-12-01

    A layered perovskite electrode material, La0.6Sr1.4MnO4+? (LSMO4), has been studied for intermediate temperature symmetrical solid oxide fuel cells (IT-SSOFCs) on La0.9Sr0.1Ga0.8Mg0.2O3-? (LSGM) electrolyte. The chemical compatibility tests indicate that no reaction occurred between LSMO4 oxide and LSGM electrolyte at temperature up to 1000 °C both in air and 5% H2. The lower conductivity in 5% H2 and higher conduction activation energy than those in air would be caused by poorer overlap of both ? and ? bonds. DFT + U calculations also show that oxygen vacancies which formed in reducing atmosphere may block the 3D hopping path for electrons or holes through Mn-O-Mn chains. For LSMO4 electrode, SEM results indicate that the electrode formed good contact with the electrolyte after being sintered at 900 °C for 2 h. At 800 °C, the polarization resistance of the LSMO4 cathode is about 0.87 ? cm2 in air, while the polarization resistance of the LSMO4 anode is about 2.07 ? cm2 in 5% H2. LSMO4 exhibits better electrochemical activity for oxygen reduction than that for hydrogen oxidation. A cell with LSGM electrolyte, LSMO4-LSGM mixture as anode and cathode simultaneously displays a maximum power density of 59 mW cm-2 at 800 °C.

  18. Visible-light-responsive photocatalysts toward water oxidation based on NiTi-layered double hydroxide/reduced graphene oxide composite materials.

    Science.gov (United States)

    Li, Bei; Zhao, Yufei; Zhang, Shitong; Gao, Wa; Wei, Min

    2013-10-23

    A visible-light responsive photocatalyst was fabricated by anchoring NiTi-layered double hydroxide (NiTi-LDH) nanosheets to the surface of reduced graphene oxide sheets (RGO) via an in situ growth method; the resulting NiTi-LDH/RGO composite displays excellent photocatalytic activity toward water splitting into oxygen with a rate of 1.968 mmol g(-1) h(-1) and a quantum efficiency as high as 61.2% at 500 nm, which is among the most effective visible-light photocatalysts. XRD patterns and SEM images indicate that the NiTi-LDH nanosheets (diameter: 100-200 nm) are highly dispersed on the surface of RGO. UV-vis absorption spectroscopy exhibits that the introduction of RGO enhances the visible-light absorption range of photocatalysts, which is further verified by the largely decreased band gap (?1.78 eV) studied by cyclic voltammetry measurements. Moreover, photoluminescence (PL) measurements indicate a more efficient separation of electron-hole pairs; electron spin resonance (ESR) and Raman scattering spectroscopy confirm the electrons transfer from NiTi-LDH nanosheets to RGO, accounting for the largely enhanced carrier mobility and the resulting photocatalytic activity in comparison with pristine NiTi-LDH material. Therefore, this work demonstrates a facile approach for the fabrication of visible-light responsive NiTi-LDH/RGO composite photocatalysts, which can be used as a promising candidate in solar energy conversion and environmental science. PMID:24066609

  19. Size Effect and Material Property Effect of the Impactor on the Damage Modes of the Single-Layer Kiewitt-8 Reticulated Dome

    Directory of Open Access Journals (Sweden)

    Li Lin

    2014-01-01

    Full Text Available The dynamic response of large space structures under accidental impact has been the subject of intense research since the occurrence of the 9/11 incident. In the present study, using the 3D ANSYS/LS-DYNA, size effect and material property effect of the impactor on the damage modes of the single-layer kiewitt-8 reticulated dome were investigated respectively, where the impactor was the cylinder and the impact direction was vertical. Firstly, Analytical results with the rigid impactor indicated that the impactor size can change the damage mode of the reticulated dome. It was found that the probability happening to the global collapse has an obvious rise with the size increase of the impactor. Furtherly, the deformable impactor was considered to figure out the difference with the rigid impactor, the comparisons indicated that the deformable impactor, who has the same mass and same striking velocity with the rigid impactor, can contribute to the occurrence of the global collapse at a certain initial striking condition.

  20. Size effect and material property effect of the impactor on the damage modes of the single-layer Kiewitt-8 reticulated dome.

    Science.gov (United States)

    Lin, Li; Fan, Feng; Zhi, XuDong; Yin, HongFeng

    2013-01-01

    The dynamic response of large space structures under accidental impact has been the subject of intense research since the occurrence of the 9/11 incident. In the present paper, using the 3D ANSYS/LS-DYNA, size effect and material property effect of the impactor on the damage modes of the single-layer Kiewitt-8 reticulated dome were investigated, respectively, where the impactor was the cylinder and the impact direction was vertical. Firstly, analytical results with the rigid impactor indicated that the impactor size can change the damage mode of the reticulated dome. It was found that the probability happening to the global collapse has an obvious rise with the size increase of the impactor. Furthermore, the deformable impactor was considered to figure out the difference with the rigid impactor; the comparisons indicated that the deformable impactor, which has the same mass and the same striking velocity with the rigid impactor, can contribute to the occurrence of the global collapse at a certain initial striking condition. PMID:24027451

  1. Selective area atomic layer deposited ZnO nanodot on self-assembled monolayer pattern using a diblock copolymer nano-template.

    Science.gov (United States)

    Kim, Doyoung; Yoon, Jaehong; Kim, Hyungjun

    2012-02-01

    ZnO nanodots were prepared by selective area atomic layer deposition (SA-ALD) on an octadecyltrichlorosilane (ODTS) self-assembly monolayers (SAMs) patterns formed using a diblock co-polymer (DBC) nanotemplate. In order to transfer well-ordered nanaotemplate in SAMs, SiO2 sacrificial layer was inserted between DBC and SAMs. Cylindrical nanoholes under 16 nm diameters were well-formed on SiO2 layer. SA-ALD of ZnO was successfully performed on by ODTS SAMs. PMID:22629984

  2. Smear layer in endodontics

    Directory of Open Access Journals (Sweden)

    Živkovi? Slavoljub

    2005-01-01

    Full Text Available Modern methods of root canal cleaning and filing are causing formation of the smear layer on treated surfaces. The aim of this paper was to review clinical aspect of smear layer in endodontics. Smear layer is the consequence of instrumentation of root canal walls and is consisted of organic and inorganic particles of cut dentine, necrotic and/or vital pulp fragments, microorganisms and their products. Existence of smear layer is affecting permeability of the radicular dentine, thus decreasing effects of canal medicaments and impairing adhesion of obturation materials in root canal. Removal of the smear layer from canal walls is possible with use of various chemical agents, ultrasonic or laser techniques. Regardless to contradictory attitudes and opinions, removing the smear layer is required for possible bacterial contamination, compromised effects of root canal medication and in order to obtain better obturation of canals 'system. .

  3. The Sacrificial Crisis

    DEFF Research Database (Denmark)

    Östman, Lars

    2007-01-01

    Med udgangspunkt i Jesus´ lidelseshistorie forsøger artiklen via den franske religionsfilosof René Girards tanker om den hellige krise at knytte an til en generel teori om en tilstand, hvor lov og ret er suspenderede. Gennem en kritisk og perspektiverende læsning af Carl Schmitt forståes denne krise som en undtagelsestilstand

  4. Organic photovoltaic cells utilizing ultrathin sensitizing layer

    Science.gov (United States)

    Forrest, Stephen R. (Ann Arbor, MI); Yang, Fan (Piscataway, NJ); Rand, Barry P. (Somers, NY)

    2011-09-06

    A photosensitive device includes a plurality of organic photoconductive materials disposed in a stack between a first electrode and a second electrode, including a first continuous layer of donor host material, a second continuous layer of acceptor host material, and at least one other organic photoconductive material disposed as a plurality of discontinuous islands between the first continuous layer and the second continuous layer. Each of these other photoconductive materials has an absorption spectra different from the donor host material and the acceptor host material. Preferably, each of the discontinuous islands consists essentially of a crystallite of the respective organic photoconductive material, and more preferably, the crystallites are nanocrystals.

  5. Estimation of the Thickness and the Material Combination of the Thermal Stress Control Layer (TSCL) for the Stellite21 Hardfaced STD61 Hot Working Tool Steel Using Three-Dimensional Finite Element Analysis

    International Nuclear Information System (INIS)

    The research on a thermal stress control layer (TSCL) begins to undertake to reduce residual stress and strain in the vicinity of the joined region between the hardfacing layer and the base part. The goal of this paper is to estimate the material combination and the thickness of TSCL for the Stellite21 hardfaced STD61 hot working tool steel via three-dimensional finite element analysis (FEA). TSCL is created by the combination of Stellite21 and STD61. The thickness of TSCL ranges from 0.5 mm to 1.5 mm. The influence of the material combination and the thickness of TSCL on temperature, thermal stress and thermal strain distributions of the hardfaced part have been investigated. The results of the investigation have been revealed that a proper material combination of TSCL is Stellite21 of 50 % and STD61 of 50 %, and its appropriate thickness is 1.0 mm

  6. Metal deposition using seed layers

    Science.gov (United States)

    Feng, Hsein-Ping; Chen, Gang; Bo, Yu; Ren, Zhifeng; Chen, Shuo; Poudel, Bed

    2013-11-12

    Methods of forming a conductive metal layers on substrates are disclosed which employ a seed layer to enhance bonding, especially to smooth, low-roughness or hydrophobic substrates. In one aspect of the invention, the seed layer can be formed by applying nanoparticles onto a surface of the substrate; and the metallization is achieved by electroplating an electrically conducting metal onto the seed layer, whereby the nanoparticles serve as nucleation sites for metal deposition. In another approach, the seed layer can be formed by a self-assembling linker material, such as a sulfur-containing silane material.

  7. Burning Graphene Layer-by-Layer

    Science.gov (United States)

    Ermakov, Victor A.; Alaferdov, Andrei V.; Vaz, Alfredo R.; Perim, Eric; Autreto, Pedro A. S.; Paupitz, Ricardo; Galvao, Douglas S.; Moshkalev, Stanislav A.

    2015-06-01

    Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000?K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in “cold-wall” reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material.

  8. Improvement of electrochemical performance of layered manganese enriched electrode material with the coating of Ni0.25Mn0.75Ox composite oxides

    International Nuclear Information System (INIS)

    Highlights: • Composite oxides Ni0.25Mn0.75Ox are used as coating material for Li1.2Ni0.2Mn0.6O2. • The electrochemical properties of Li1.2Ni0.2Mn0.6O2 are improved after coating. • The composite metal oxides are more effective than single metal oxides or fluorides. - Abstract: Layered solid solution cathode Li1.2Ni0.2Mn0.6O2 has been synthesized and coated by composite oxides Ni0.25Mn0.75Ox with varying amounts (2, 5 and 8 wt%) in this paper. The effect of coated Ni0.25Mn0.75Ox on the physical and electrochemical properties of the materials has been discussed through the characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), electrochemical impedance spectroscopy (EIS), discharge, cyclic performance and rate capability. The discharge capacities and coulombic efficiencies of Li1.2Ni0.2Mn0.6O2 in the first cycle have been improved and increase with the increasing content of coated Ni0.25Mn0.75Ox. The 8 wt% Ni0.25Mn0.75Ox coated Li1.2Ni0.2Mn0.6O2 delivers 298 mA h g?1 for the first discharge capacity and 91.9% for the first coulombic efficiency, compared with 228 mA h g?1 and 66.1% for pristine Li1.2Ni0.2Mn0.6O2. However, the 5 wt% Ni0.25Mn0.75Ox coated Li1.2Ni0.2Mn0.6O2 shows the best capacity retention (94.2% for 80 cycles) and rate capability (106 mA h g?1 at 10 °C). Electrochemical impedance spectroscopy (EIS) results show that the Rct of Li1.2Ni0.2Mn0.6O2 electrode decreases after coating, which is responsible for superior rate capability

  9. Oxygen-reducing catalyst layer

    Science.gov (United States)

    O'Brien, Dennis P. (Maplewood, MN); Schmoeckel, Alison K. (Stillwater, MN); Vernstrom, George D. (Cottage Grove, MN); Atanasoski, Radoslav (Edina, MN); Wood, Thomas E. (Stillwater, MN); Yang, Ruizhi (Halifax, CA); Easton, E. Bradley (Halifax, CA); Dahn, Jeffrey R. (Hubley, CA); O'Neill, David G. (Lake Elmo, MN)

    2011-03-22

    An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

  10. Interference layer metallography

    International Nuclear Information System (INIS)

    Refractory metallic materials for application in Gas Cooled High Temperature Reactors are age-hardened nickel or iron base alloys. To control their behaviour and to adapt it to realistic load conditions, these materials have to be subjected to suitable informing tests and characterized. In the past few years, interference layer metallography has proved to be a highly flexible characterization procedure, suitable as an independent investigation method as well as an outstanding way of sample preparation for application of automatic quantitative image analysis to refractory alloys. This paper reports the problems of characterization of the Ni and Fe base alloys to be solved by interference layer metallography and the physical background of this method. The procedure of chromatic contrasting is discussed. From these considerations arises the result that for technical applications the optimum layer material for each special sample should be selected a priori. For that purpose it is necessary to measure the optical constants of the respective structural elements of the alloys as well as those of the candidate layer materials. The measuring procedures are discussed in detail. A routine procedure is deduced which allows to determine a priori the layer material and thickness fitting best to a given problem. (orig.)

  11. The contact properties to TISI/sub 2/ and the adhesion within sub-micron contact holes of etched back CVD w/adhesion layer films

    International Nuclear Information System (INIS)

    A CVD tungsten deposition and etch back process was developed which renders the contact hole coplanar with the oxide surface and forms little, if any, keyhole within the plug. The etch back is performed without the incorporation of a sacrificial planarizing layer. This deposition scheme, in combination with differing adhesion layers, was studied with respect to contact resistance and chemical stability to TiSi/sub 2/, as well as to adhesion within submicron contact holes. All layerings studied exhibited low values of contact resistance, and only adhesion layers of pure Ti showed a measurable level of interfacial fluorine (AES). In addition, W growth directly atop TiSi/sub 2/ was shown feasible under certain conditions. A large variation in adhesion performance was observed for the layerings studied. This ranged from layerings which ''popped'' out of contact holes during etch back, to layerings which allowed the plug, itself, to be severed during sample cleaving

  12. Processes for multi-layer devices utilizing layer transfer

    Energy Technology Data Exchange (ETDEWEB)

    Nielson, Gregory N; Sanchez, Carlos Anthony; Tauke-Pedretti, Anna; Kim, Bongsang; Cederberg, Jeffrey; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J

    2015-02-03

    A method includes forming a release layer over a donor substrate. A plurality of devices made of a first semiconductor material are formed over the release layer. A first dielectric layer is formed over the plurality of devices such that all exposed surfaces of the plurality of devices are covered by the first dielectric layer. The plurality of devices are chemically attached to a receiving device made of a second semiconductor material different than the first semiconductor material, the receiving device having a receiving substrate attached to a surface of the receiving device opposite the plurality of devices. The release layer is etched to release the donor substrate from the plurality of devices. A second dielectric layer is applied over the plurality of devices and the receiving device to mechanically attach the plurality of devices to the receiving device.

  13. Examination of the geometry-dependent anisotropic material behavior in additive layer manufacturing for the calculation of mesoscopic lightweight structures: Presentation held at the Direct Digital Manufacturing Conference, March 14 - 15, 2012, Berlin; DDMC 2012

    OpenAIRE

    Reinhart, Gunter; Teufelhart, Stefan; Riss, Fabian Karl Eberhard

    2012-01-01

    Due to the producible geometric complexity, additive layer manufacturing (ALM) processes show a high potential for the production of lightweight components. Especially mesoscopic approaches, like honeycombs or lattice structures, exhibit very advantageous mechanical properties like stiffness or strength combined with low masses. To achieve an optimum structure, a regular buildup out of equal elementary cells is not ideal. Rather, an adjustment of the course of the structure and its material f...

  14. Cobalt nanoparticles as sacrificial templates for the electrodeposition of palladium nanomaterials in an ionic liquid, and its application to electrochemical sensing of hydrazine

    International Nuclear Information System (INIS)

    We report on the electrodeposition of palladium nanomaterials in choline chloride-based ionic liquid ethaline. A glassy carbon electrode (GCE) was modified with cobalt nanoparticles (acting as sacrificial templates) and a GCE modified with palladium nanoparticles (PdNPs) were fabricated and used to study the electrocatalytic oxidation of hydrazine (N2H4). Scanning electron microscopy revealed that the PdNP modified GCE has a uniform morphology. Zero current potentiometry was used for in-situ probing the changes in interfacial potential of the oxidation of hydrazine. An amperometric study showed that the PdNP modified GCE possesses excellent electrocatalytic activity towards N2H4. The modified electrode displays a fast response (-1)-1 cm-2) and broad linearity in the range from 0.1 to 800 ?mol L-1 with a detection limit of 0.03 ?mol L-1 (S/N = 3). (author)

  15. Hierarchically porous silicon–carbon–nitrogen hybrid materials towards highly efficient and selective adsorption of organic dyes

    OpenAIRE

    Meng, Lala; Zhang, Xiaofei; Tang, Yusheng; Su, Kehe; KONG, JIE

    2015-01-01

    The hierarchically macro/micro-porous silicon–carbon–nitrogen (Si–C–N) hybrid material was presented with novel functionalities of totally selective and highly efficient adsorption for organic dyes. The hybrid material was conveniently generated by the pyrolysis of commercial polysilazane precursors using polydivinylbenzene microspheres as sacrificial templates. Owing to the Van der Waals force between sp2-hybridized carbon domains and triphenyl structure of dyes, and electrostatic interactio...

  16. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  17. Evolution Of Lattice Structure And Chemical Composition Of The Surface Reconstruction Layer In Li1.2Ni0.2Mn0.6O2 Cathode Material For Lithium Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Pengfei; Nie, Anmin; Zheng, Jianming; Zhou, Yungang; Lu, Dongping; Zhang, Xiaofeng; Xu, Rui; Belharouak, Ilias; Zu, Xiaotao; Xiao, Jie; Amine, Khalil; Liu, Jun; Gao, Fei; Shahbazian-Yassar, Reza; Zhang, Jiguang; Wang, Chong M.

    2015-01-14

    Voltage and capacity fading of layer structured lithium and manganese rich (LMR) transition metal oxide is directly related to the structural and composition evolution of the material during the cycling of the battery. However, understanding such evolution at atomic level remains elusive. Based on atomic level structural imaging, elemental mapping of the pristine and cycled samples and density functional theory calculations, it is found that accompanying the hoping of Li ions is the simultaneous migration of Ni ions towards the surface from the bulk lattice, leading to the gradual depletion of Ni in the bulk lattice and thickening of a Ni enriched surface reconstruction layer (SRL). Furthermore, Ni and Mn also exhibit concentration partitions within the thin layer of SRL in the cycled samples where Ni is almost depleted at the very surface of the SRL, indicating the preferential dissolution of Ni ions in the electrolyte. Accompanying the elemental composition evolution, significant structural evolution is also observed and identified as a sequential phase transition of C2/m ?I41?Spinel. For the first time, it is found that the surface facet terminated with pure cation is more stable than that with a mixture of cation and anion. These findings firmly established how the elemental species in the lattice of LMR cathode transfer from the bulk lattice to surface layer and further into the electrolyte, clarifying the long standing confusion and debate on the structure and chemistry of the surface layer and their correlation with the voltage fading and capacity decaying of LMR cathode. Therefore, this work provides critical insights for designing of cathode materials with both high capacity and voltage stability during cycling.

  18. Production of polystyrene spheres for use as a templating material for polyaniline monolith structures.

    OpenAIRE

    Gorey, Brian; White, Blanaid; Morrin, Aoife; Smyth, Malcolm R.

    2011-01-01

    Polystyrene (PS) spheres are potentially useful as a reproducible, sacrificial templating material for monolith columns once they can be utilised to create a uniform microstructured packing which enables a higher monolith batch to batch reproducibility. To achieve PS spheres which can meet these requirements, their synthesis was optimised. Parameters investigated included variation of reactant concentrations, along with optimisation of reaction conditions temperature, agitation speed and nitr...

  19. Characterization of nickel-based microlattice materials with structural hierarchy from the nanometer to the millimeter scale

    International Nuclear Information System (INIS)

    Novel nickel-based microlattice materials with structural hierarchy spanning three different length scales (nm, ?m, mm) are characterized microstructurally and mechanically. These materials are produced by plating a sacrificial template obtained by self-propagating photopolymer waveguide prototyping. Ni–P films with a thickness of 120 nm to 3 ?m are deposited by electroless plating, whereas thicker films (5–26 ?m) are obtained by subsequent electrodeposition of a pure Ni layer. This results in cellular materials spanning three orders of magnitude in relative density, from 0.01% to 8.5%. The thin electroless Ni–P films have ultra-fine grain size (7 nm) and a yield strength of ?2.5 GPa, whereas the thicker electrodeposited Ni films exhibit a much broader distribution with average grain size of 116 nm and strong (1 0 0) texture in the plating direction, resulting in a yield strength of ?1 GPa. Uniaxial compression experiments reveal two distinct mechanical responses. At ultra-low densities (<0.1%), these lattices exhibit nearly full recovery after strains up to more than 50%, and damping coefficients an order of magnitude larger than for conventional Ni foams. At higher densities (0.1–10%), the compression behavior is fully plastic, similar to traditional cellular metals. A simple mechanical analysis reveals that the transition occurs when the thickness-to-diameter ratio of the truss elements is of the order of the yield strain of the material, in agreement with experimental observations. Optical and electron imaging of deformed lattices show that the deformation largely localizes around the nodes. In the ultra-light regime, the microlattice materials are stiffer and stronger than any existing alternative.

  20. Organic electronic devices with multiple solution-processed layers

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, Stephen R.; Lassiter, Brian E.; Zimmerman, Jeramy D.

    2015-08-04

    A method of fabricating a tandem organic photosensitive device involves depositing a first layer of an organic electron donor type material film by solution-processing of the organic electron donor type material dissolved in a first solvent; depositing a first layer of an organic electron acceptor type material over the first layer of the organic electron donor type material film by a dry deposition process; depositing a conductive layer over the interim stack by a dry deposition process; depositing a second layer of the organic electron donor type material over the conductive layer by solution-processing of the organic electron donor type material dissolved in a second solvent, wherein the organic electron acceptor type material and the conductive layer are insoluble in the second solvent; depositing a second layer of an organic electron acceptor type material over the second layer of the organic electron donor type material film by a dry deposition process, resulting in a stack.

  1. Structural, mechanical and magnetic properties studies on high-energy Kr-ion irradiated Fe{sub 3}O{sub 4} material (main corrosion layer of Fe-based alloys)

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jianrong, E-mail: sunjr@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Zhiguang; Zhang, Hongpeng; Song, Peng; Chang, Hailong; Cui, Minghuan; Pang, Lilong; Zhu, Yabin [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Fashen [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2014-12-15

    The Fe-based (T91 and RAFM) alloys are considered as the promising candidate structural materials for DEMO and the first fusion power plant, and these two kinds of steels suffered more serious corrosion attack at 450 °C in liquid PbBi metal. So in order to further clarify the applicability of Fe-based structural materials in nuclear facilities, we should study not only the alloys itself but also its corrosion layers; and in order to simplify the discussion and clarify the irradiation effects of the different corrosion layer, we abstract the Fe{sub 3}O{sub 4} (main corrosion layer of Fe-based alloys) to study the structural, micro-mechanical and magnetic properties under 2.03 GeV Kr-ion irradiation. The initial crystallographic structure of the Fe{sub 3}O{sub 4} remains unaffected after irradiation at low damage levels, but as the Kr-ion fluence increases and the defects accumulate, the macroscopic magnetic properties (M{sub s}, H{sub c}, etc.) and micro-mechanical properties (nano-hardness and Young’s modulus) are sensitive to high-energy Kr-ion irradiation and exhibit excruciating uniform changing regularities with varying fluences (firstly increases, then decreases). And these magnetism, hardening and softening phenomena can be interpreted very well by the effects related to the stress and defects (the production, accumulation and free) induced by high-energy ions irradiation.

  2. Single layers of WS2 nanoplates embedded in nitrogen-doped carbon nanofibers as anode materials for lithium-ion batteries

    Science.gov (United States)

    Yu, Sunmoon; Jung, Ji-Won; Kim, Il-Doo

    2015-07-01

    Single layers of WS2 nanoplates are uniformly embedded in nitrogen-doped carbon nanofibers (WS2@NCNFs) via a facile electrospinning method. Crystallization of the single-layered WS2 nanoplates and in situ nitrogen doping into the carbon nanofibers were simultaneously accomplished during a two-step heat treatment. The distinctive structure of the WS2@NCNFs enables outstanding electrochemical performances.Single layers of WS2 nanoplates are uniformly embedded in nitrogen-doped carbon nanofibers (WS2@NCNFs) via a facile electrospinning method. Crystallization of the single-layered WS2 nanoplates and in situ nitrogen doping into the carbon nanofibers were simultaneously accomplished during a two-step heat treatment. The distinctive structure of the WS2@NCNFs enables outstanding electrochemical performances. Electronic supplementary information (ESI) available: Experimental section, SEM images of WS2 powder and ground WS2 powder, TEM image and SAED pattern of the WS2 powder, Raman spectra of the WS2 powder, CV curves of the WS2 powder, voltage profiles of the WS2 powder, schematic diagram of WS2@NCNFs undergoing lithium storage reactions, electrochemical performance of NCNFs, morphologies and EDS mapping of WS2@NCNFs after cycling, and a table of contributions of NCNFs to the specific capacity. See DOI: 10.1039/c5nr02425k

  3. Topology optimization of free-layer damping material on a thin panel for maximizing modal loss factors expressed by only real eigenvalues

    Science.gov (United States)

    Yamamoto, Takashi; Yamada, Takayuki; Izui, Kazuhiro; Nishiwaki, Shinji

    2015-12-01

    Damping material is usually applied to steel panels of vehicles to reduce vibration levels. On the other hand, the weight of a vehicle must be reduced to improve the rate of fuel consumption. Therefore, the modal loss factors caused by the treatment of damping material on the steel panels of a vehicle body structure must be maximized within a given volume. In this paper, we propose a practical design method to maximize modal loss factors by optimizing the layout of damping material under a volume constraint. The modal loss factor for an eigenmode can be obtained conventionally by the modal strain energy method as the material loss factor multiplied by the ratio of the strain energy stored in the damping material over the total strain energy in the system under consideration. In the proposed method, we assume that the eigenvectors with damping material are almost identical with the eigenvectors without damping material. The modal loss factor can then be expressed approximately by using a corresponding real eigenvalue, for which the stiffness of the damping material is taken into account but its mass density is set to zero and ignored. Several numerical examples are provided to demonstrate that the proposed method obtains optimal layouts of damping material applied to a flat rectangular panel. Our results indicate that the damping material is mainly distributed in areas where strain energy is stored, which agrees well with the results obtained using conventional design methodologies. Moreover, by applying a design sensitivity filter that was improved recently, the layout of damping material can be unified into a single domain to meet practical requirements for manufacturing.

  4. Enhanced magnetocaloric effect material

    Science.gov (United States)

    Lewis, Laura J. H.

    2006-07-18

    A magnetocaloric effect heterostructure having a core layer of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, and a constricting material layer coated on at least one surface of the magnetocaloric material core layer. The constricting material layer may enhance the magnetocaloric effect by restriction of volume changes of the core layer during application of a magnetic field to the heterostructure. A magnetocaloric effect heterostructure powder comprising a plurality of core particles of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, wherein each of the core particles is encapsulated within a coating of a constricting material is also disclosed. A method for enhancing the magnetocaloric effect within a giant magnetocaloric material including the step of coating a surface of the magnetocaloric material with a constricting material is disclosed.

  5. Polymer-Layer Silicate Nanocomposites

    DEFF Research Database (Denmark)

    Potarniche, Catalina-Gabriela

    2012-01-01

    Nowadays, some of the material challenges arise from a performance point of view as well as from recycling and biodegradability. Concerning these aspects, the development of polymer layered silicate nanocomposites can provide possible solutions. This study investigates how to obtain polymer layered silicate nanocomposites and their structure-properties relationship. In the first part of the thesis, thermoplastic layered silicates were obtained by extrusion. Different modification methods were te...

  6. Presentation of a reference material for the spatially resolved hydrogen analytics in near-surface layers by means of nuclear-reaction analysis; Darstellung eines Referenzmaterials fuer die ortsaufgeloeste Wasserstoffanalytik in oberflaechennahen Schichten mittels Kernreaktionsanalyse

    Energy Technology Data Exchange (ETDEWEB)

    Reinholz, U.

    2005-10-03

    The object of the thesis is the presentation of the theory of the {sup 15}N-reaction analysis (NRA), the experiemental construction of the corresponding beam pipe at the ion accelerator of the BAM and the evaluation of the measurement results. The aim is the first characterization of a reference material for the H analytics on the base of amorphous silicon (aSi) on a Si[100] substrate. The homogeneity of the aSi:H layers deposited by means of CVD was studied. For this pro substrate for about 30 samples the hydrogen depth profiles were measures, folded by means of a program created within the thesis and subjected to a statistical evaluation. The result were mean value ans standard deviation of the hydrogen concentration as well as an estimator for the contribution of the inhomogeneity to the measurement uncertainty. The stability of the potential reference material was proved by the constancy of result of repeated measurements of the hydrogen concentration during the application of a large dose of {sup 15}N ions. In an international ring experiment the reproducibility of the measurement results was proved. For the characterization of the aSi:H layers beside the NRA the white-light interferometry, ellipsometry, profilometry, and X-ray reflectometry, as well as the IR and Raman spectroscopy were used. The stoichiometry of the applied standard material kapton was checked by means of NMR spectroscopy and CHN analysis.

  7. Mg-doping for improved long-term cyclability of layered Na-ion cathode materials - The example of P2-type NaxMg0.11Mn0.89O2

    Science.gov (United States)

    Buchholz, Daniel; Vaalma, Christoph; Chagas, Luciana Gomes; Passerini, Stefano

    2015-05-01

    Sodium-ion batteries (SIBs) are establishing themselves as a low-cost alternative to the widespread lithium-ion technology, a trend that is exemplified by the use of aluminium as anode current collector. In order to be in line with this philosophy, environmentally friendly, abundant and cheap materials need to be used in order to provide a complementary rather than competing battery technology other than lithium-ion. With the same scope in mind, herein we present the structural and electrochemical characterization of P2-type NaxMg0.11Mn0.89O2 material to demonstrate the effectiveness of Mg-doping for the development of future layered cathode materials. Of particular interest is the effect on the long-term cyclability (200 cycles), which has not been reported, yet. As shown in the manuscript, a Mg content as low as 11% in the MO2 layer leads to a smoothing of the potential profile, very high coulombic efficiencies exceeding 99.5% at 12 mA g-1 and a stable long-term cycling behaviour.

  8. Investigation of the turbulent mixing of thin layers of materials of different density during the laser acceleration of flat multilayer targets in the Iskra-4 facility

    International Nuclear Information System (INIS)

    The results of the first experiments devised to investigate the mixing of thin layers of Al and Au during the laser acceleration of flat three-layer targets of Si (5 ?m), Al (2 ?m), and Au (0.05-0.26 ?m) by radiation converted to the second harmonic from the Iskra-4 iodine laser with an intensity of 4x1013-7x1013 W/cm2 (?0.5?1 ns), which acts on the Si side of the target. A method for detecting the occurrence of mixing is developed. It is established that under the experimental conditions the thickness of the mixing region is at least ?0.15 ?m. The results of a theoretical analysis of the evolution of the disturbances leading to mixing are presented

  9. The proton exchange chemistry of layered Ni(OH)2 for two types of high-capacity cathode materials in rechargeable batteries

    International Nuclear Information System (INIS)

    Based on the studies of the first proton exchange/remove of layered Ni(OH)2, super nickel oxide has been prepared with strongly alkaline concentrated sodium hypochlorite solution. The primary alkaline super nickel battery equipped with the prepared NiOOH cathode provides an energy capacity 2 times as large as that of the existing alkaline manganese batteries under high drain. In addition, according to the second proton exchange of Ni(OH)2, the layered NiOOLi has also been synthesized by means of the proton/Li-ion exchange of super nickel oxide in LiOH solution, and then in molten lithium hydroxide. It provides higher discharge voltage and capacity than that of the widely adopted LiCoO2 and LiMn2O4

  10. In Situ X?Ray Diffraction Studies on Structural Changes of a P2 Layered Material during Electrochemical Desodiation/Sodiation

    DEFF Research Database (Denmark)

    Jung, Young Hwa; Christiansen, Ane Sælland

    2015-01-01

    Sodium layered oxides with mixed transition metals have received significant attention as positive electrode candidates for sodium?ion batteries because of their high reversible capacity. The phase transformations of layered compounds during electrochemical reactions are a pivotal feature for understanding the relationship between layered structures and electrochemical properties. A combination of in situ diffraction and ex situ X?ray absorption spectroscopy reveals the phase transition mechanism for the ternary transition metal system (Fe–Mn–Co) with P2 stacking. In situ synchrotron X?ray diffraction using a capillary?based microbattery cell shows a structural change from P2 to O2 in P2–Na0.7Fe0.4Mn0.4Co0.2O2 at the voltage plateau above 4.1 V on desodiation. The P2 structure is restored upon subsequent sodiation. The lattice parameter c in the O2 structure decreases significantly, resulting in a volumetric contraction of the lattice toward a fully charged state. Observations on the redox behavior of each transition metal in P2–Na0.7Fe0.4Mn0.4Co0.2O2 using X?ray absorption spectroscopy indicate that all transition metals are involved in the reduction/oxidation process.

  11. Rapid Prototyping Of Layered Composite Parts

    Science.gov (United States)

    Wolff, Edwin D.

    1992-01-01

    Numerically controlled cutting accelerates fabrication of layers. Proposed method derived from stereoscopic lithography. CATIA or CAEDS computer program used to generate three-dimensional mathematical model of prototype part. In model, geometry of part specified in layers, as in stereoscopic lithography. Model data for each layer fed to computer-numerically-controlled ultrasonic cutting machine. Sheet of prepreg (uncured composite material) of specified layer thickness placed in machine and cut, under control of model data, to specified shape of layer.

  12. Impact of a sacrificial anode as assessed by zinc accumulation in different organs of the oyster Crassostrea gigas: results from long- and short-term laboratory tests.

    Science.gov (United States)

    Caplat, Christelle; Mottin, Elmina; Lebel, Jean-Marc; Serpentini, Antoine; Barillier, Daniel; Mahaut, Marie-Laure

    2012-05-01

    Sacrificial anodes made of zinc are currently used in marine environments to mitigate marine corrosion as part of CP systems of immerged metallic structures. The aim of this work was to study zinc bioconcentration in the oyster Crassostrea gigas by performing two in vivo tests during different time periods and at different zinc concentrations. The first test was conducted during a period of 10 weeks at a concentration of 0.53 ± 0.04 mg Zn L(-1) to simulate long-term exposure, and a second test was conducted during a 168-hour period at a concentration of 10.2 ± 1.2 mg Zn L(-1) to reproduce short-term exposure. In these experiments, the zinc source was an electrochemical device that included a sacrificial anode to mimic the in situ conditions. During the first 14 days of the long-term experiment, digestive glands of C oysters exhibited bioaccumulation of zinc that varied according to the oysters' reproductive cycle. Both a bioconcentration factor (BCF) of ? 13,397 and a zinc accumulation percentage of +297% of zinc occurred in this organ after 10 weeks. The results obtained from the short-term test showed a lower BCF of 405 but a faster bioaccumulation of zinc (starting from the first day) in the same organ. No mortality was observed in long-term assay, but 81.8% of the oysters died at the end of the short-term assay. These results demonstrate the great capacity of C. gigas to accumulate zinc released from the anode, especially when low concentrations are released, as in the case of anode dissolution used as CP. This study confirmed the necessity to monitor this zinc-contamination source in marine environments in relation to the usual oyster consumption by humans (especially in France). No implication for human health of this zinc-contamination source was demonstrated until now, and this was not the purpose of this study; however, zinc remains one of the most abundant nutritionally essential elements in the human body that may affect the human immune system at high-level uptake. PMID:22183875

  13. Suspended carbon nanotube nanocomposite beams with a high mechanical strength via layer-by-layer nano-self-assembly

    Science.gov (United States)

    Lee, Dongjin; Cui, Tianhong

    2011-04-01

    The fabrication and characterization of single-walled carbon nanotube (SWCNT) composite thin film micropatterns and suspended beams prepared by lithography-compatible layer-by-layer (LbL) nano-self-assembly are demonstrated. Negatively charged SWCNTs are assembled with a positively charged polydiallyldimethylammonium chloride, and the composite thin film is patterned by oxygen plasma etching with a masking layer of photoresist, resulting in a feature size of 2 µm. Furthermore, the SWCNT nanocomposite stripe pattern with a metal clamp on both ends is released by etching a sacrificial layer of silicon dioxide in the hydrofluoric acid vapor. I-V measurement reveals that the resistance of SWCNT nanocomposite film decreases by 23% upon release, presumably due to the effect of reorientation of CNTs caused by the deflection of about 50 nm. A high Young's modulus is found in a range of 500-800 GPa based on the characterization of a fixed-fixed beam using nanoindentation. This value is much higher than those of the other CNT-polymer composites reported due to organization of structures by self-assembly and higher loading of CNTs. The stiff CNT-polymer composite thin film micropattern and suspended beam have potential applications to novel physical sensors, nanoelectromechanical switches, other M/NEMS devices, etc.

  14. Suspended carbon nanotube nanocomposite beams with a high mechanical strength via layer-by-layer nano-self-assembly

    International Nuclear Information System (INIS)

    The fabrication and characterization of single-walled carbon nanotube (SWCNT) composite thin film micropatterns and suspended beams prepared by lithography-compatible layer-by-layer (LbL) nano-self-assembly are demonstrated. Negatively charged SWCNTs are assembled with a positively charged polydiallyldimethylammonium chloride, and the composite thin film is patterned by oxygen plasma etching with a masking layer of photoresist, resulting in a feature size of 2 ?m. Furthermore, the SWCNT nanocomposite stripe pattern with a metal clamp on both ends is released by etching a sacrificial layer of silicon dioxide in the hydrofluoric acid vapor. I-V measurement reveals that the resistance of SWCNT nanocomposite film decreases by 23% upon release, presumably due to the effect of reorientation of CNTs caused by the deflection of about 50 nm. A high Young's modulus is found in a range of 500-800 GPa based on the characterization of a fixed-fixed beam using nanoindentation. This value is much higher than those of the other CNT-polymer composites reported due to organization of structures by self-assembly and higher loading of CNTs. The stiff CNT-polymer composite thin film micropattern and suspended beam have potential applications to novel physical sensors, nanoelectromechanical switches, other M/NEMS devices, etc.

  15. Suspended carbon nanotube nanocomposite beams with a high mechanical strength via layer-by-layer nano-self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Lee Dongjin; Cui Tianhong, E-mail: tcui@me.umn.edu [Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455 (United States)

    2011-04-22

    The fabrication and characterization of single-walled carbon nanotube (SWCNT) composite thin film micropatterns and suspended beams prepared by lithography-compatible layer-by-layer (LbL) nano-self-assembly are demonstrated. Negatively charged SWCNTs are assembled with a positively charged polydiallyldimethylammonium chloride, and the composite thin film is patterned by oxygen plasma etching with a masking layer of photoresist, resulting in a feature size of 2 {mu}m. Furthermore, the SWCNT nanocomposite stripe pattern with a metal clamp on both ends is released by etching a sacrificial layer of silicon dioxide in the hydrofluoric acid vapor. I-V measurement reveals that the resistance of SWCNT nanocomposite film decreases by 23% upon release, presumably due to the effect of reorientation of CNTs caused by the deflection of about 50 nm. A high Young's modulus is found in a range of 500-800 GPa based on the characterization of a fixed-fixed beam using nanoindentation. This value is much higher than those of the other CNT-polymer composites reported due to organization of structures by self-assembly and higher loading of CNTs. The stiff CNT-polymer composite thin film micropattern and suspended beam have potential applications to novel physical sensors, nanoelectromechanical switches, other M/NEMS devices, etc.

  16. Natural melanin composites by layer-by-layer assembly

    Science.gov (United States)

    Eom, Taesik; Shim, Bong Sub

    2015-04-01

    Melanin is an electrically conductive and biocompatible material, because their conjugated backbone structures provide conducting pathways from human skin, eyes, brain, and beyond. So there is a potential of using as materials for the neural interfaces and the implantable devices. Extracted from Sepia officinalis ink, our natural melanin was uniformly dispersed in mostly polar solvents such as water and alcohols. Then, the dispersed melanin was further fabricated to nano-thin layered composites by the layer-by-layer (LBL) assembly technique. Combined with polyvinyl alcohol (PVA), the melanin nanoparticles behave as an LBL counterpart to from finely tuned nanostructured films. The LBL process can adjust the smart performances of the composites by varying the layering conditions and sandwich thickness. We further demonstrated the melanin loading degree of stacked layers, combination nanostructures, electrical properties, and biocompatibility of the resulting composites by UV-vis spectrophotometer, scanning electron microscope (SEM), multimeter, and in-vitro cell test of PC12, respectively.

  17. Towards high-energy and durable lithium-ion batteries via atomic layer deposition: elegantly atomic-scale material design and surface modification

    Science.gov (United States)

    Meng, Xiangbo

    2015-01-01

    Targeted at fueling future transportation and sustaining smart grids, lithium-ion batteries (LIBs) are undergoing intensive investigation for improved durability and energy density. Atomic layer deposition (ALD), enabling uniform and conformal nanofilms, has recently made possible many new advances for superior LIBs. The progress was summarized by Liu and Sun in their latest review [1], offering many insightful views, covering the design of nanostructured battery components (i.e., electrodes and solid electrolytes), and nanoscale modification of electrode/electrolyte interfaces. This work well informs peers of interesting research conducted and it will also further help boost the applications of ALD in next-generation LIBs and other advanced battery technologies.

  18. Minority carrier lifetime in type-2 InAs-GaSb strained-layer superlattices and bulk HgCdTe materials

    Science.gov (United States)

    Donetsky, Dmitry; Belenky, Gregory; Svensson, Stefan; Suchalkin, Sergei

    2010-08-01

    Minority carrier lifetime, ?, in type-2 strained-layer superlattices (SLSs) and in long-wave Hg0.78Cd0.22Te (MCT) was measured by optical modulation response technique. It was shown that at 77 K radiative recombination can contribute to the measured ? values. The Shockley-Read-Hall (SRH) lifetimes were attained as 100 ns, 31 ns, and more than 1 ?s for midwave infrared superlattices, long-wave infrared (LWIR) superlattices, and MCT correspondingly. The nature of the difference between the SRH lifetimes in LWIR superlattice and MCT is discussed.

  19. Synthesis of hierarchical NiCo2O4 hollow nanorods via sacrificial-template accelerate hydrolysis for electrochemical glucose oxidation.

    Science.gov (United States)

    Yang, Jiao; Cho, Misuk; Lee, Youngkwan

    2016-01-15

    Hierarchical NiCo2O4 hollow nanorods (HR) were directly grown on stainless steel via a sacrificial template accelerated hydrolysis and post calcination using ZnO nanorod as a template. The composition of the NiCo2O4 HR electrode was determined using X-ray diffraction and X-ray photoelectron spectroscopy. The morphology of the NiCo2O4 HR is comprised of nanoflakes that were characterized with scanning electron microscopy and transmission electron microscopy. The mixed-valence metal oxide and hollow structure provided high chemical reactivity and a large surface area for glucose oxidation in an alkaline solution. Under an optimal applied potential of +0.6 V, the developed NiCo2O4 HR electrode showed a broad detection range of 0.0003–1.0 mM, a sensitivity of 1685.1 ?A mM?1 cm?2, and a low detection limit of 0.16 ?M. These results represent a significant improvement over both NiO and Co3O4 HR. The developed NiCo2O4 HR electrode not only demonstrated excellent selectivity in the presence of several electro-active species, but also exhibited high stability following a 200 cycles voltammetry test. PMID:26281005

  20. PRESSURE-IMPULSE DIAGRAM OF MULTI-LAYERED ALUMINUM FOAM PANELS UNDER BLAST PRESSURE

    Directory of Open Access Journals (Sweden)

    CHANG-SU SHIM

    2013-06-01

    Full Text Available Anti-terror engineering has increasing demand in construction industry, but basis of design (BOD is normally not clear for designers. Hardening of structures has limitations when design loads are not defined. Sacrificial foam claddings are one of the most efficient methods to protect blast pressure. Aluminum foam can have designed yield strength according to relative density and mitigate the blast pressure below a target transmitted pressure. In this paper, multi-layered aluminum foam panels were proposed to enhance the pressure mitigation by increasing effective range of blast pressure. Through explicit finite element analyses, the performance of blast pressure mitigation by the multi-layered foams was evaluated. Pressure-impulse diagrams for the foam panels were developed from extensive analyses. Combination of low and high strength foams showed better applicability in wider range of blast pressure.

  1. Direct Selective Laser Sintering/Melting of High Density Alumina Powder Layers at Elevated Temperatures

    Science.gov (United States)

    Deckers, J.; Meyers, S.; Kruth, J. P.; Vleugels, J.

    Direct selective laser sintering (SLS) or selective laser melting (SLM) are additive manufacturing techniques that can be used to produce three-dimensional ceramic parts directly, without the need for a sacrificial binder. In this paper, a low laser energy density is applied to SLS/SLM high density powder layers of sub-micrometer alumina at elevated temperatures (up to 800°C). In order to achieve this, a furnace was designed and built into a commercial SLS machine. This furnace was able to produce a homogeneously heated cylindrical zone with a height of 60 mm and a diameter of 32 mm. After optimizing the layer deposition and laser scanning parameters, two ceramic parts with a density up to 85% and grain sizes as low as 5 ?m were successfully produced.

  2. The formation of a SiOx interfacial layer on low-k SiOCH materials fabricated in ULSI application

    International Nuclear Information System (INIS)

    The characterizations of SiOCH films using oxygen plasma treatment depends linearly on the O2/CO flow rate ratio. According to the results of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses, it was found that the carbon composition decreases with increasing O2/CO flow rate ratio, because more carbon in the Si-O-C and Si-CH3 bonds on the film surface would be converted by oxygen radicals. It was believed that the oxygen plasma could oxidize the SiOCH films and form a SiOx interfacial capping layer without much porosity. Moreover, the result of FTIR analysis revealed that there was no water absorbed on the film. A SiO2-like capping layer formed at the SiOCH film by the O2/CO flow rate ratio of 0.75 had nearly the same dielectric properties from the result of capacitance-voltage (C-V) measurement in our research

  3. Effect of insulating layer material on RF-induced heating for external fixation system in 1.5?T MRI system.

    Science.gov (United States)

    Liu, Yan; Kainz, Wolfgang; Qian, Songsong; Wu, Wen; Chen, Ji

    2014-09-01

    The radio frequency (RF)-induced heating is a major concern when patients with medical devices are placed inside a magnetic resonance imaging (MRI) system. In this article, numerical studies are applied to investigate the potentials of using insulated materials to reduce the RF heating for external fixation devices. It is found that by changing the dielectric constant of the insulation material, the RF-induced heating at the tips of devices can be altered. This study indicates a potential technique of developing external fixation device with low MRI RF heating. PMID:23781983

  4. NiO layers grown on a Ni substrate by galvanostatic anodization as a positive electrode material for aqueous hybrid capacitors

    Science.gov (United States)

    Chiku, Masanobu; Toda, Masanari; Higuchi, Eiji; Inoue, Hiroshi

    2015-07-01

    A NiO positive electrode for aqueous hybrid capacitors was prepared by a new galvanostatic anodization method. A thin sheet of heat-treated Ni was galvanostatically oxidized in aqueous 85% H3PO4 containing 0.5 M NH4F. During the anodization, the thickness of the Ni metal sheet decreased from 10 to 2 ?m and 2- to 3-?m-thick NiO layers were formed on both sides of the Ni metal sheet. A hybrid capacitor comprising the anodized NiO positive electrode, an activated carbon negative electrode, and aqueous 10 M KOH exhibited a maximum specific energy of 16 W h kg-1 and a specific power of 22.2 kW kg-1.

  5. Propagation of waves in micropolar generalized thermoelastic materials with two temperatures bordered with layers or half-spaces of inviscid liquid

    Scientific Electronic Library Online (English)

    Rajneesh, Kumar; Mandeep, Kaur; S.C., Rajvanshi.

    2014-12-01

    Full Text Available The aim of the present paper is to study the propagation of Lamb waves in micropolar generalized thermoelastic solids with two temperatures bordered with layers or half-spaces of inviscid liquid subjected to stress-free boundary conditions in the context of Green and Lindsay (G-L) theory. The secula [...] r equations for governing the symmetric and skew-symmetric leaky and nonleaky Lamb wave modes of propagation are derived. The computer simulated results with respect to phase velocity, attenuation coefficient, amplitudes of dilatation, microrotation vector and heat flux in case of symmetric and skew-symmetric modes have been depicted graphically. Moreover, some particular cases of interest have also been discussed.

  6. Materials, design and processing of air encapsulated MEMS packaging

    Science.gov (United States)

    Fritz, Nathan T.

    This work uses a three-dimensional air cavity technology to improve the fabrication, and functionality of microelectronics devices, performance of on-board transmission lines, and packaging of micro-electromechanical systems (MEMS). The air cavity process makes use of the decomposition of a patterned sacrificial polymer followed by the diffusion of its by-products through a curing polymer overcoat to obtain the embedded air structure. Applications and research of air cavities have focused on simple designs that concentrate on the size and functionality of the particular device. However, a lack of guidelines for fabrication, materials used, and structural design has led to mechanical stability issues and processing refinements. This work investigates improved air gap cavities for use in MEMS packaging processes, resulting in fewer fabrication flaws and lower cost. The identification of new materials, such as novel photo-definable organic/inorganic hybrid polymers, was studied for increased strength and rigidity due to their glass-like structure. A novel epoxy polyhedral oligomeric silsesquioxane (POSS) material was investigated and characterized for use as a photodefineable, permanent dielectrics with improved mechanical properties. The POSS material improved the air gap fabrication because it served as a high-selectivity etch mask for patterning sacrificial materials as well as a cavity overcoat material with improved rigidity. An investigation of overcoat thickness and decomposition kinetics provided a fundamental understanding of the properties that impart mechanical stability to cavities of different shape and volume. Metallization of the cavities was investigated so as to provide hermetic sealing and improved cavity strength. The improved air cavity, wafer-level packages were tested using resonator-type devices and chip-level lead frame packaging. The air cavity package was molded under traditional lead frame molding pressures and tested for mechanical integrity. The development of mechanical models complimented the experimental studies. A model of the overcoat materials used the film properties and elastic deformations to study the stress-strain behavior of the suspended dielectric films under external forces. The experimental molding tests and mechanical models were used to establish processing conditions and physical designs for the cavities as a function of cavity size. A novel, metal-free chip package was investigated combining the in-situ thermal decomposition of the sacrificial material during post-mold curing of the lead frame molding compound. Sacrificial materials were characterized for their degree of decomposition during the molding cure to provide a chip package with improved mechanical support and no size restrictions. Improvements to the air cavities for MEMS packaging led to investigations and refinements of other microfabrication processes. The sacrificial polycarbonate materials were shown to be useful as temporary bonding materials for wafer-level bonding. The release temperature and conditions of the processed wafer can be changed based on the polycarbonates formulation. The electroless deposition of metal was investigated as an alternative process for metalizing the air cavities. The deposition of silver and copper using a Sn/Ag catalyst as a replacement for costly palladium activation was demonstrated. The electroless deposition was tested on polymer and silicon dioxide surfaces for organic boards and through-silicon vias.

  7. Full-scale study of a building equipped with phase change material wallboards and a multi-layer rack latent heat thermal energy store system

    OpenAIRE

    Borderon, J.; Virgone, J.; Cantin, R.; Kuznik, F.

    2010-01-01

    An office building in Lyon, France has been studied. Phase Change Material (PCM) has been installed as wallboard and as latent heat thermal energy storage system coupled with the ventilation system. The main purpose of this study is to determine if the PCM system can guarantee the summer comfort of the occupants without energy-consuming cooling devices. Sensors have been set up and the collected data are monitored to study the thermal behavior of the building and the PCM. Numerical simulation...

  8. AFM study of advanced composite materials for organic photovoltaic cells with active layer based on P3HT:PCBM and chiral photosensitive liquid crystalline dopants.

    Czech Academy of Sciences Publication Activity Database

    Iwan, A.; Sikora, A.; Hamplová, V?ra; Bubnov, Alexej

    2015-01-01

    Ro?. 42, ?. 7 (2015), s. 964-972. ISSN 0267-8292 R&D Projects: GA MŠk 7AMB13PL041; GA ?R GA13-14133S; GA MŠk(CZ) LD14007; GA MŠk 7AMB13PL038 Grant ostatní: AV?R(CZ) M100101204 Institutional support: RVO:68378271 Keywords : AFM * chiral liquid crystal * organic solar cells * azo compounds * photovoltaics Subject RIV: JJ - Other Materials Impact factor: 2.486, year: 2014

  9. Room temperature large-scale synthesis of layered frameworks as low-cost 4?V cathode materials for lithium ion batteries

    Science.gov (United States)

    Hameed, A. Shahul; Reddy, M. V.; Nagarathinam, M.; Run?evski, Tom?e; Dinnebier, Robert E; Adams, Stefan; Chowdari, B. V. R.; Vittal, Jagadese J.

    2015-01-01

    Li-ion batteries (LIBs) are considered as the best available technology to push forward the production of eco-friendly electric vehicles (EVs) and for the efficient utilization of renewable energy sources. Transformation from conventional vehicles to EVs are hindered by the high upfront price of the EVs and are mainly due to the high cost of LIBs. Hence, cost reduction of LIBs is one of the major strategies to bring forth the EVs to compete in the market with their gasoline counterparts. In our attempt to produce cheaper high-performance cathode materials for LIBs, an rGO/MOPOF (reduced graphene oxide/Metal-Organic Phosphate Open Framework) nanocomposite with ~4?V of operation has been developed by a cost effective room temperature synthesis that eliminates any expensive post-synthetic treatments at high temperature under Ar/Ar-H2. Firstly, an hydrated nanocomposite, rGO/K2[(VO)2(HPO4)2(C2O4)]·4.5H2O has been prepared by simple magnetic stirring at room temperature which releases water to form the anhydrous cathode material while drying at 90?°C during routine electrode fabrication procedure. The pristine MOPOF material undergoes highly reversible lithium storage, however with capacity fading. Enhanced lithium cycling has been witnessed with rGO/MOPOF nanocomposite which exhibits minimal capacity fading thanks to increased electronic conductivity and enhanced Li diffusivity. PMID:26593096

  10. Room temperature large-scale synthesis of layered frameworks as low-cost 4?V cathode materials for lithium ion batteries.

    Science.gov (United States)

    Hameed, A Shahul; Reddy, M V; Nagarathinam, M; Run?evski, Tom?e; Dinnebier, Robert E; Adams, Stefan; Chowdari, B V R; Vittal, Jagadese J

    2015-01-01

    Li-ion batteries (LIBs) are considered as the best available technology to push forward the production of eco-friendly electric vehicles (EVs) and for the efficient utilization of renewable energy sources. Transformation from conventional vehicles to EVs are hindered by the high upfront price of the EVs and are mainly due to the high cost of LIBs. Hence, cost reduction of LIBs is one of the major strategies to bring forth the EVs to compete in the market with their gasoline counterparts. In our attempt to produce cheaper high-performance cathode materials for LIBs, an rGO/MOPOF (reduced graphene oxide/Metal-Organic Phosphate Open Framework) nanocomposite with ~4?V of operation has been developed by a cost effective room temperature synthesis that eliminates any expensive post-synthetic treatments at high temperature under Ar/Ar-H2. Firstly, an hydrated nanocomposite, rGO/K2[(VO)2(HPO4)2(C2O4)]·4.5H2O has been prepared by simple magnetic stirring at room temperature which releases water to form the anhydrous cathode material while drying at 90?°C during routine electrode fabrication procedure. The pristine MOPOF material undergoes highly reversible lithium storage, however with capacity fading. Enhanced lithium cycling has been witnessed with rGO/MOPOF nanocomposite which exhibits minimal capacity fading thanks to increased electronic conductivity and enhanced Li diffusivity. PMID:26593096

  11. Preparation and dielectric properties of SiC nanowires self-sacrificially templated by carbonated bacterial cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Lixia; Ma, Yongjun; Dai, Bo [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zhou, Yong [Eco-materials and Renewable Energy Research Center (ERERC), School of Physics, National Lab of Solid State Microstructure, ERERC, Nanjing University, Nanjing 210093 (China); Liu, Jinsong [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Pei, Chonghua, E-mail: peichonghua@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ? A new material – CBC is introduced as a template to prepare SiC nanowires. ? SiC nanowires are synthesized by the infiltration process of reactive vapor Si. ? The highest ?? of ?-SiC nanowires is obtained at 1400 °C. -- Abstract: SiC nanowires were synthesized by the infiltration process of reactive vapor Si in Ar atmosphere at 1350–1450 °C, using carbonated bacterial cellulose (CBC) as carbon template and a reactant. Scanning electron microscopy (SEM), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and vector network analyzer were employed to characterize the samples. The diameter of the resulting ?-SiC nanowires changes with calcination temperatures, specifically, 35–60 nm for 1350 °C, 40–80 nm for 1400 °C, and 30–60 nm for 1450 °C. The ?-SiC nanowires obtained at 1400 °C possess the highest ?? of complex permittivity.

  12. Photocatalytic O2 evolution from water over Zn–Cr layered double hydroxides intercalated with inorganic anions

    International Nuclear Information System (INIS)

    Graphical abstract: The photocatalytic activity of Zn–Cr LDHs intercalated with various inorganic anions was studied by O2 evolution from aqueous solution of AgNO3 as a sacrificial agent. All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. The interlayer anions affected the photocatalytic activity of the LDHs. - Highlights: • Zn–Cr layered double hydroxides intercalated with inorganic anions were synthesized. • Photocatalytic activity of the LDHs was studied by O2 evolution. • All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. • The interlayer anions affected the photocatalytic activity of the LDHs. - Abstract: Zn–Cr layered double hydroxides (LDHs) intercalated with inorganic anions (CO32?, Cl?, SO42? and NO3?) were synthesized by the co-precipitation method and the anion exchange process. The photocatalytic activity of the LDHs was studied by O2 evolution from aqueous solution of AgNO3 as a sacrificial agent. All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. Besides, the interlayer anions affected the photocatalytic activity of the LDHs. After irradiation, Ag particles were formed on the LDHs by accepting the electrons generated during the photocatalytic reaction

  13. In situ-prepared composite materials of PEDOT: PSS buffer layer-metal nanoparticles and their application to organic solar cells

    Science.gov (United States)

    2012-01-01

    We report an enhancement in the efficiency of organic solar cells via the incorporation of gold (Au) or silver (Ag) nanoparticles (NPs) in the hole-transporting buffer layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), which was formed on an indium tin oxide (ITO) surface by the spin-coating of PEDOT:PSS-Au or Ag NPs composite solution. The composite solution was synthesized by a simple in situ preparation method which involved the reduction of chloroauric acid (HAuCl4) or silver nitrate (AgNO3) with sodium borohydride (NaBH4) solution in the presence of aqueous PEDOT:PSS media. The NPs were well dispersed in the PEDOT:PSS media and showed a characteristic absorption peak due to the surface plasmon resonance effect. Organic solar cells with the structure of ITO/PEDOT:PSS-Au, Ag NPs/poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM)/LiF/Al exhibited an 8% improvement in their power conversion efficiency mainly due to the enlarged surface roughness of the PEDOT:PSS, which lead to an improvement in the charge collection and ultimately improvements in the short-circuit current density and fill factor. PMID:23173992

  14. Ultrathin atomic layer deposited ZrO2 coating to enhance the electrochemical performance of Li4Ti5O12 as an anode material

    International Nuclear Information System (INIS)

    Atomic layer deposition (ALD) was used to deposit ZrO2 directly on Li4Ti5O12 electrode to improve its electrochemical performance. The thickness of the deposited ZrO2 was controlled by adjusting ALD cycles from 0 to 1, 2, 5, 10 and 50. The Li4Ti5O12 electrodes with and without ZrO2 coating were characterized by scanning electron microscope, energy dispersive X-ray spectroscopy, high-resolution transmission electron microscope, cyclic voltammetry (CV) and galvanostatic charge-discharge test. The CV result indicated that ZrO2 coating with 2, 5 and 10 ALD cycles could effectively reduce the electrochemical polarization of the Li4Ti5O12 electrode. Charge-discharge test revealed that the Li4Ti5O12 electrodes with 1-, 2- and 5-cycle ZrO2 coating exhibited higher specific capacity, better cycling performance and rate capability than the pristine Li4Ti5O12 in a voltage range of 0.1–2.5 V. However, ZrO2 coating with more than 5 ALD cycles could lead to degraded performance of Li4Ti5O12. Mechanism for the enhanced electrochemical performance of Li4Ti5O12 was explored by electrochemical impedance spectroscopy, and the reason was attributed to the suppressed formation of solid electrolyte interphase and the improved electron transport by ultrathin ZrO2 coating

  15. Investigation of chemical bonding states at interface of Zn/organic materials for analysis of early stage of inorganic/organic hybrid multi-layer formation

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Ken, E-mail: k_cho@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Japan Science and Technology Agency, CREST (Japan); Takenaka, Kosuke; Setsuhara, Yuichi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Japan Science and Technology Agency, CREST (Japan); Shiratani, Masaharu [Department of Electronics, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Japan Science and Technology Agency, CREST (Japan); Sekine, Makoto; Hori, Masaru [Plasma Nanotechnology Research Center, Nagoya University Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Japan Science and Technology Agency, CREST (Japan)

    2012-11-15

    Interactions between Ar-O{sub 2} mixture plasmas and Zn thin film on polyethylene terephthalate (PET) were investigated using the combinatorial plasma process analyzer, on the basis of nondestructive depth analyses of chemical bonding states at Zn thin film and Zn/PET interface via hard X-ray photoelectron spectroscopy (HXPES). After the Ar-O{sub 2} plasma exposure, peak-area ratio of O 1 s to Zn 2p{sub 3/2} evaluated from the HXPES spectra is found to increase with increasing the ion saturation current Multiplication-Sign time and saturated at the value obtained from ZnO. The HXPES C 1 s spectra measured at a take-off angle (TOA) of 80 Degree-Sign showed insignificant change in oxygen functionalities (O=C-O bond and C-O bond) after the deposition of Zn thin film and the plasma exposure. Whereas, the HXPES C 1 s spectra measurement at a TOA of 20 Degree-Sign suggested that the oxygen functionalities degraded in shallower regions up to about a few nanometer from the Zn/PET interface due to deposition of Zn thin film. However, after the plasma exposure, oxidation of PET substrate at the degraded layer of Zn/PET interface was caused by oxygen radicals and/or ions, which diffused through the Zn thin film.

  16. Fabrication of bioinspired nanostructured materials via colloidal self-assembly

    Science.gov (United States)

    Huang, Wei-Han

    Through millions of years of evolution, nature creates unique structures and materials that exhibit remarkable performance on mechanicals, opticals, and physical properties. For instance, nacre (mother of pearl), bone and tooth show excellent combination of strong minerals and elastic proteins as reinforced materials. Structured butterfly's wing and moth's eye can selectively reflect light or absorb light without dyes. Lotus leaf and cicada's wing are superhydrophobic to prevent water accumulation. The principles of particular biological capabilities, attributed to the highly sophisticated structures with complex hierarchical designs, have been extensively studied. Recently, a large variety of novel materials have been enabled by natural-inspired designs and nanotechnologies. These advanced materials will have huge impact on practical applications. We have utilized bottom-up approaches to fabricate nacre-like nanocomposites with "brick and mortar" structures. First, we used self-assembly processes, including convective self-assembly, dip-coating, and electrophoretic deposition to form well oriented layer structure of synthesized gibbsite (aluminum hydroxide) nanoplatelets. Low viscous monomer was permeated into layered nanoplatelets and followed by photo-curing. Gibbsite-polymer composite displays 2 times higher tensile strength and 3 times higher modulus when compared with pure polymer. More improvement occurred when surface-modified gibbsite platelets were cross-linked with the polymer matrix. We observed ˜4 times higher strength and nearly 1 order of magnitude higher modulus than pure polymer. To further improve the mechanical strength and toughness of inorganicorganic nanocomposites, we exploited ultrastrong graphene oxide (GO), a single atom thick hexagonal carbon sheet with pendant oxidation groups. GO nanocomposite is made by co-filtrating GO/polyvinyl alcohol suspension on 0.2 im pore-sized membrane. It shows ˜2 times higher strength and ˜15 times higher ultimate strains than nacre and pure GO paper (also synthesized by filtration). Specifically, it exhibits ˜30 times higher fracture energy than filtrated graphene paper and nacre, ˜100 times tougher than filtrated GO paper. Besides reinforced nanocomposites, we further explored the self-assembly of spherical colloids and the templating nanofabrication of moth-eye-inspired broadband antireflection coatings. Binary crystalline structures can be easily accomplished by spin-coating double-layer nonclose-packed colloidal crystals as templates, followed by colloidal templating. The polymer matrix between self-assembled colloidal crystal has been used as a sacrificial template to define the resulting periodic binary nanostructures, including intercalated arrays of silica spheres and polymer posts, gold nanohole arrays with binary sizes, and dimple-nipple antireflection coatings. The binary-structured antireflection coatings exhibit better antireflective properties than unitary coatings. Natural optical structures and nanocomposites teach us a great deal on how to create high performance artificial materials. The bottom-up technologies developed in this thesis are scalable and compatible with standard industrial processes, promising for manufacturing high-performance materials for the benefits of human beings.

  17. A facile and novel organic coprecipitation strategy to prepare layered cathode material Li[Li0.2Mn0.54Ni0.13Co0.13]O2 with high capacity and excellent cycling stability

    Science.gov (United States)

    Yuan, Xiaolei; Xu, Qun-jie; Wang, Cong; Liu, Xinnuan; Liu, Haimei; Xia, Yongyao

    2015-04-01

    The lithium-rich layered cathode material Li[Li0.2Mn0.54Ni0.13Co0.13]O2 with high capacity and excellent cycling stability, is successfully synthesized through a facile organic co-precipitation route. The as-obtained material exhibits a well-crystallization and uniform size distribution, above which have been characterized and observed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, FT-IR spectra proves that the addition of metal ions Mn+ induces a red-shift of the bond of C-N groups of the 8-hydroxyquinoline, which is used as the precipitant in this work, and most probably due to the strong complexation effect of metal ions Mn+ with N and O atoms of 8-hydroxyquinoline, and simultaneously the co-precipitation process occurred. The electrochemical results reveal that the cathode material derived from this novel organic co-precipitation route exhibits improved electrochemical performance, of which could provide an initial discharge capacity of 287.2 mAhg-1at 0.2C within a potential range of 2.0-4.8 V at room temperature, even at high C-rate of 2C, this material could also deliver a capacity of 212.1 mAh g-1 with 97.7% capacity retention after 100 cycles. Therefore, it is proposed that this organic co-precipitation might be a high-efficiency strategy to synthesize alternative electrode materials with improved performance.

  18. New Structures of the Super-Resolution Near-Field Phase-Change Optical Disk and a New Mask-Layer Material

    Science.gov (United States)

    Shi, Lu Ping; Chong, Tow Chong

    The removable and rewritable high-density phase-change optical disk is attractive for high-definition television (HDTV), digital TV and internet downloading. Super-resolution near-field technology is one of the most promising technologies for achieving ultra-high density recording and is considered a more feasible way of near-field optical recording with simpler recording-head design, less mechanical damage, no contamination and higher recording speed. Developing new structures and searching for new mask materials are two important issues.

  19. Characterization of a test device for determination of the half value layer and of filtration with quality equity of materials in accordance with standard ABNT NBR IEC 60601-1-3

    International Nuclear Information System (INIS)

    The motivation of this work was the development and validation of a device to perform the tests established by ABNT NBR IEC 60601-1-3 versions published in 2001 and 2011. The purpose of the tests is to determine the half-value layer – HVL and filtration with equivalent filtration quality in mmAl, materials that intercept the X-ray beam from their emission to the X-ray image receiving device. This filtration includes all the materials present in radiation source assembly, formed by the x-ray tube housing with x-ray tube inserted, the collimator (inherent filtration) and by materials present in the patients support, as Table and wall bucky, both incorporate image receiving device which is also evaluated. In the development was taken in consideration the routine of tests execution routine, in order to reduce the operator interaction with the system and in order to reduce the human factor in the execution, reflecting directly on the measurement uncertainty, in the runtime reduction of the runtime and radiation safety. The device was validated with respect to: a) Effect of positioning and distribution of the filters in the filter changer device; b) Influence of purity of the aluminum filter used in the device, and c) Comparison tests carried out with the testing device with respect to the tests carried out with a reference X-ray generator. (author)

  20. Synthesis and Electrochemical Properties of Layered Li(Co0.5Ni0.5)1- y Fe y O2 (0 ? y ? 0.10) as a Cathode Material for Lithium-Ion Batteries

    Science.gov (United States)

    Cheng, Cuixia; Chen, Fang; Yi, Huiyang

    2015-10-01

    A rheological phase method has been successfully applied to synthesize a layered lithium nickel cobalt iron oxide Li(Co0.5 Ni0.5)1- y Fe y O2 (0 ? y ? 0.10), a promising cathode material of lithium-ion batteries. The impacts of Fe content and reaction conditions on the material structure are characterized by means of x-ray diffraction, scanning electron microscopy and transmission electron microscopy. Electrochemical properties are investigated in detail under different conditions as cathode materials of lithium-ion batteries. It is found that the average sizes of the prepared powders are about 100 nm. Compared to other samples, Li(Co0.5Ni0.5)0.95Fe0.05O2 shows the lowest cation mixing, the smallest impedance, the best reversible capacity and cycling performance. The initial discharge capacity is 146.9 mAhg-1 in 3.0-4.3 V. The cyclability is better after several cycles, which shows great prospects for use in lithium-ion batteries.