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. In-situ deposition of sacrificial layers during ion implantation

    International Nuclear Information System (INIS)

    The retained dose of implanted ions is limited by sputtering. It is known that a sacrificial layer deposited prior to ion implantation can lead to an enhanced retained dose. However, a higher ion energy is required to obtain a similar implantation depth due to the stopping of ions in the sacrificial layer. It is desirable to have a sacrificial layer of only a few monolayers thickness which can be renewed after it has been sputtered away. We explain the concept and describe two examples: (i) metal ion implantation using simultaneously a vacuum arc ion source and filtered vacuum arc plasma sources, and (ii) Metal Plasma Immersion Ion Implantation and Deposition (MePIIID). In MePIIID, the target is immersed in a metal or carbon plasma and a negative, repetitively pulsed bias voltage is applied. Ions are implanted when the bias is applied while the sacrificial layer suffers sputtering. Low-energy thin film deposition - repair of the sacrificial layer -- occurs between bias pulses. No foreign atoms are incorporated into the target since the sacrificial film is made of the same ion species as used in the implantation phase

  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. Cleaning graphene with a titanium sacrificial layer

    International Nuclear Information System (INIS)

    Graphene is a promising material for future electronic applications and chemical vapor deposition of graphene on copper is a promising method for synthesizing graphene on the wafer scale. The processing of such graphene films into electronic devices introduces a variety of contaminants which can be difficult to remove. An approach to cleaning residues from the graphene channel is presented in which a thin layer of titanium is deposited via thermal e-beam evaporation and immediately removed. This procedure does not damage the graphene as evidenced by Raman spectroscopy, greatly enhances the electrical performance of the fabricated graphene field effect transistors, and completely removes the chemical residues from the surface of the graphene channel as evidenced by x-ray photoelectron spectroscopy.

  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. Use of Amphoteric Copolymer Films as Sacrificial Layers for Constructing Free-Standing Layer-by-Layer Films

    OpenAIRE

    Baozhen Wang; Yu Tokuda; Koji Tomida; Shigehiro Takahashi; Katsuhiko Sato; Jun-ichi Anzai

    2013-01-01

    The present paper reports the use of an amphoteric copolymer, poly(diallylamine-co-maleic acid) (PDAMA), as a component of precursor layers (or sacrificial layers) for constructing free-standing layer-by-layer (LbL) films. A PDAMA-poly(styrenesulfonate) (PSS) film or PDAMA-poly(dimethyldiallylammonium chloride) (PDDA) film was coated on the surface of a quartz slide at pH 4.0 or 8.0, respectively, as a sacrificial layer that can be removed by changing the pH. The surface of the sacrificial la...

  10. Fabrication of polymer microstructures for MEMS: sacrificial layer micromolding and patterned substrate micromolding.

    Science.gov (United States)

    Ferrell, Nicholas; Woodard, James; Hansford, Derek

    2007-12-01

    Two soft lithography based fabrication techniques are employed for fabricating mechanically independent, freely suspended polymer microstructure from poly(n-propyl methacrylate) (PPMA), poly(methyl methacrylate) (PMMA), and polystyrene. Both methods involve a micromolding process followed by thermal bonding to the substrate. The first method, sacrificial layer micromolding, uses a water soluble sacrificial layer, allowing functional structures to be released by immersion in water. The second method, patterned substrate micromolding, uses a permanent substrate patterned via photolithography. Functional regions of the polymer MEMS are suspended over the voids in the photoresist pattern. The processes have been applied to the fabrication of polymer microstructures with a variety of geometries for specific applications. Devices have included microcantilevers, beams, and other more complicated microstructures. The thermal molding process is conceivably applicable to the fabrication of microstructures from a wide variety of thermoplastic polymers, allowing material selection to be tailored based on application. PMID:17564840

  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. Use of Amphoteric Copolymer Films as Sacrificial Layers for Constructing Free-Standing Layer-by-Layer Films

    Directory of Open Access Journals (Sweden)

    Baozhen Wang

    2013-06-01

    Full Text Available The present paper reports the use of an amphoteric copolymer, poly(diallylamine-co-maleic acid (PDAMA, as a component of precursor layers (or sacrificial layers for constructing free-standing layer-by-layer (LbL films. A PDAMA-poly(styrenesulfonate (PSS film or PDAMA-poly(dimethyldiallylammonium chloride (PDDA film was coated on the surface of a quartz slide at pH 4.0 or 8.0, respectively, as a sacrificial layer that can be removed by changing the pH. The surface of the sacrificial layer was further covered with LbL films composed of poly(allylamine hydrochloride (PAH and PSS. The PAH-PSS films were released from the substrate upon immersing the film-coated quartz slide in acidic or neutral/basic solution, respectively, as a result of the pH-induced dissolution of the PDAMA-PDDA or PDAMA-PSS sacrificial layer. Thus, PDAMA-based sacrificial layers have been demonstrated to dissolve in both acidic and neutral solutions, depending on the type of counter polymer. The thicknesses of the sacrificial layers and released LbL films are crucial factors for constructing free-standing LbL films. The releasing kinetics also depended on the thickness of the crucial layers. The free-standing PAH-PSS films obtained were stable in water or in air in the dry state. PDAMA-based sacrificial layers may be useful in constructing free-standing LbL films containing biomolecules with limited pH stability.

  13. Sacrificial adhesion promotion layers for copper metallization of device structures.

    Science.gov (United States)

    Zong, Yinfeng; Shan, Xiaoying; Watkins, James J

    2004-10-12

    The adhesion of copper films to adjacent device layers including TiN, Ta, and TaN diffusion barriers is a crucial reliability issue for integrated circuits. We report that ultrathin layers of poly(acrylic acid) (PAA) prepared on barrier surfaces or on the native oxide of Si wafers dramatically increase the interfacial adhesion of Cu films deposited by the H2 assisted reduction of bis(2,2,7-trimethyloctane-3,5-dionato)copper in supercritical carbon dioxide. Similar improvements were achieved on Si wafers using a simple vapor phase exposure of the substrate to acrylic acid prior to metallization. The deposited films and the substrate/Cu interfaces were analyzed by X-ray photoelectron spectroscopy (XPS), electron microscopy, atomic force microscopy, and variable-angle spectroscopic ellipsometry. No trace of the adhesion layer was detected at the interface, indicating it was sacrificial at the deposition conditions used. Moreover, the presence and subsequent decomposition of the PAA layer during deposition substantially reduced or eliminated metal oxides at the substrate interface. For depositions on PAA-treated Si wafers, copper was present primarily as Cu0 at the interface and Si was present only as Si0. On PAA-treated Ta substrates, XPS analysis indicated Ta was present primarily as Ta0 at the metallized interface whereas Ta2O5 dominated the interface of samples prepared without the adhesion layers. The technique can be extended to patterned substrates using adsorption of acrylic acid or thermal/UV polymerization of acrylic acid. PMID:15461508

  14. Processing of Graphite-Based Sacrificial Layer for Microfabrication of Low Temperature Co-fired Ceramics (LTCC)

    OpenAIRE

    Birol, Hansu; Maeder, Thomas; Ryser, Peter

    2006-01-01

    The processing and application of graphite powder-based sacrificial layer for fabrication of microfluidic structures in LTCC is described. Such layers are produced as pastes, which are screen-printed in LTCC sheets to avoid sagging, by supporting closed, three-dimensional structures such as channels, membranes during firing. The aim of the paper is to highlight the selection of paste materials and the effects of processing conditions on the fabricated micro-fluidic components. It is see...

  15. 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.

  16. Tuneable Capacitor based on dual picks profile of the sacrificial layer

    CERN Document Server

    Soulimane, S; Chapuis, F; Charvet, P -L; aïd, M

    2008-01-01

    In this paper, we present a novel dual gap tuneable capacitor process based on the profile of the sacrificial layer. This profile involves a tri-layer photo-resist process with only one mask level. This realization is based on a special profile of the sacrificial layer designed by two picks. The mechanism of the sacrificial layer realisation is dependent on resist thickness, resist formulation (viscosity, type of polymer and/or solvent, additives...), design of the patterned layer (size or width) and the conditions under which this layer is prepared: thermal treatment, etch back processes... In this communication we demonstrate influence of the later parameters and discuss how a dual pick profile was achieved.

  17. Phosphorus diffusion gettering process of multicrystalline silicon using a sacrificial porous silicon layer

    OpenAIRE

    Lotfi, Derbali; Hatem, Ezzaouia

    2012-01-01

    The aims of this work are to getter undesirable impurities from low-cost multicrystalline silicon (mc-Si) wafers and then enhance their electronic properties. We used an efficient process which consists of applying phosphorus diffusion into a sacrificial porous silicon (PS) layer in which the gettered impurities have been trapped after the heat treatment. As we have expected, after removing the phosphorus-rich PS layer, the electrical properties of the mc-Si wafers were significantly improved...

  18. 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.

  19. Fabrication of LTCC Micro-fluidic Devices Using Sacrificial Carbon Layers

    OpenAIRE

    Birol, Hansu; Maeder, Thomas; Jacq, Caroline; Corradini, Giancarlo; Passerini, Reynald; Fournier, Yannick; Strässler, Sigfrid; Ryser, Peter

    2005-01-01

    Ease of fabrication and design flexibility are two attractive features of low temperature co-fired ceramics (LTCC) technology for fabrication of complex micro-fluidic devices. Such structures are designed and processed using different shaping methods, the extent and complexity of which depends on the final device specifications (dimensions, mechanical and functional properties). In this work, we propose a sacrificial layer method based on carbon-black paste, which burns out during the L...

  20. Vanadium sacrificial layers as a novel approach for the fabrication of freestanding Heusler Shape Memory Alloys

    OpenAIRE

    Helmich, Lars; Teichert, Niclas; Hetaba, Walid; Behler, Anna; Waske, Anja; Klimova, Svetlana; Huetten, Andreas

    2015-01-01

    In this study we report a method for the preparation of freestanding magnetocaloric thin films. Non-stoichiometric Heusler alloys Ni-Mn-Sn, Ni-Co-Mn-Sn and Ni-Co-Mn-Al are prepared via sputter deposition. A sacrificial vanadium layer is added between the substrate and the Heusler film. By means of selective wet-chemical etching the vanadium layer can be removed. Conditions for the crystallization of Vanadium layers and epitaxial growth of the Heusler films are indicated. Mag...

  1. A novel sacrificial-layer process based on anodic bonding and its application in an accelerometer

    Science.gov (United States)

    Wang, Lingyun; He, Yong; Zhan, Zhan; Yu, Lingke; Wang, Huan; Chen, Daner

    2015-04-01

    It is found in our experiments that the depletion layer of anodic bonding is etched faster than the bulk glass (Pyrex 7740) in hydrofluoric acid (HF). Based on this interesting phenomenon, a novel process of a sacrificial layer is proposed in this paper. In order to deeply understand and investigate the rules concerning the influence of bonding parameters on this effect, firstly the width of the depletion layer under different bonding voltages and temperatures and the selection ratio of etching are revealed. To validate the feasibility of the method, a micro-machined accelerometer is designed and fabricated. The test results of resonant frequency and sensitivity of the fabricated accelerometer are 3254.5 Hz and 829.85-844.93 mV/g, respectively. This was further evidence that the depletion layer could be used as a sacrificial layer and the removable structure could be successfully released by fast etching this layer. The important feature of this method is that only one mask is needed in the whole process and therefore it could greatly simplify the fabrication process of the device.

  2. 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

  3. Multifunctional polyelectrolyte multilayers as nanofiltration membranes and as sacrificial layers for easy membrane cleaning.

    Science.gov (United States)

    Ilyas, Shazia; de Grooth, Joris; Nijmeijer, Kitty; de Vos, Wiebe M

    2015-05-15

    This manuscript investigates the modification of an ultra-filtration (UF) membrane support with polyelectrolyte multilayers (PEMs) consisting of the weak polyelectrolytes poly(allyl amine) hydrochloride (PAH) and poly(acrylic acid) (PAA). These prepared polyelectrolyte multilayer membranes have a dual function: They act as nanofiltration (NF) membranes and as sacrificial layers to allow easy cleaning of the membranes. In order to optimize the conditions for PEM coating and removal, adsorption and desorption of these layers on a model surface (silica) was first studied via optical reflectometry. Subsequently, a charged UF membrane support was coated with a PEM and after each deposited layer, a clear increase in membrane resistance against pure water permeation and a switch of the zeta potential were observed. Moreover these polyelectrolyte multilayer membranes, exhibited rejection of solutes in a range typical for NF membranes. Monovalent ions (NaCl) were hardly rejected (60% were observed for a neutral organic molecule sulfamethoxazole (SMX) and for the divalent ion SO3(2-). The rejection mechanism of these membranes seems to be dominated by size-exclusion. To investigate the role of these PEMs as sacrificial layers for the cleaning of fouled membranes, the prepared polyelectrolyte multilayers were fouled with silica nano particles. Subsequent removal of the coating using a rinse and a low pressure backwash with pH 3, 3M NaNO3 allowed for a drop in membrane resistance from 1.7?10(14)m(-1) (fouled membrane) to 9.9?10(12)m(-1) (clean membrane), which is nearly equal to that of the pristine membrane (9.7?10(12)m(-1)). Recoating of the support membrane with the same PEMs resulted in a resistance equal to the resistance of the original polyelectrolyte multilayer membrane. Interestingly, less layers were needed to obtain complete foulant removal from the membrane surface, than was the case for the model surface. The possibility for backwashing allows for an even more successful use of the sacrificial layer approach in membrane technology than on model surfaces. Moreover, these PEMs can be used to provide a dual function, as NF membranes and as a Sacrificial coating to allow easy membrane cleaning. PMID:25554085

  4. 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 &#...

  5. Combined TMAH and HF sacrificial layer etching technique for surface micromachined devices

    Science.gov (United States)

    Lisec, Thomas; Kreutzer, Martin; Wenk, Beatrice; Wagner, Bernd

    1995-09-01

    This paper presents a two step sacrifical layer etching technique used for the fabrication of surface mciromachined piezoresistive pressure sensors. The sacrificial layer itself is a sandwich structure of a thin polysilicon layer with the underetching channels and a much thicker 'buried' oxide underneath. First the polysilicon part is etched in an aqueous TMAH solution with high etch rates realizing a first shallow cavity. After rinsing, the oxide part is removed in 7:1 buffered HF. Since the oxide is etched now vertically, the process is completed within minutes. Sticking is suppressed successfully and non special drying techniques are required. The whole sensor structures could be passivated by LPCVD or PECVD layers against both etchants. Although the final depth of the cavity is 1 micrometers the sensor structure remains nearly flat. This minimizes technological problems concerning for example the piezoresistor definition or the sealing of the sensor and reduces the noise in the piezoresistor arrangement.

  6. 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

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

    International Nuclear Information System (INIS)

    Throughout this investigation, experiments on laser ablation with silicon (Si) wafers have been performed using silicon nitride (Si3N4) as a sacrificial layer to find the optimal fluence capable of removing the Si3N4, 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 Si3N4 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).

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

    Science.gov (United States)

    Lerner, B.; Perez, M. S.; Toro, C.; Lasorsa, C.; Rinaldi, C. A.; Boselli, A.; Lamagna, A.

    2012-01-01

    Throughout this investigation, experiments on laser ablation with silicon (Si) wafers have been performed using silicon nitride (Si 3N 4) as a sacrificial layer to find the optimal fluence capable of removing the Si 3N 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 3N 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. 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.

  10. 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.

  11. Tribological altruism: A sacrificial layer mechanism of synovial joint lubrication in articular cartilage.

    Science.gov (United States)

    Chan, S M T; Neu, C P; DuRaine, G; Komvopoulos, K; Reddi, A H

    2012-09-21

    Boundary lubrication is characterized by sliding surfaces separated by a molecularly thin film that reduces friction and wear of the underlying substrate when fluid lubrication cannot be established. In this study, the wear and replenishment rates of articular cartilage were examined in the context of friction coefficient changes, protein loss, and direct imaging of the surface ultrastructure, to determine the efficiency of the boundary lubricant (BL) layer. Depletion of cartilage lubricity occurred with the concomitant loss of surface proteoglycans. Restoration of lubrication by incubation with synovial fluid was much faster than incubation with culture media and isolated superficial zone protein. The replenishment action of the BL layer in articular cartilage was rapid, with the rate of formation exceeding the rate of depletion of the BL layer to effectively protect the tissue from mechanical wear. The obtained results indicate that boundary lubrication in articular cartilage depends in part on a sacrificial layer mechanism. The present study provides insight into the natural mechanisms that minimize wear and resist tissue degeneration over the lifetime of an organism. PMID:22867761

  12. Comparative study of LPE and VPE silicon thin film on porous sacrificial layer

    International Nuclear Information System (INIS)

    Thin film single crystal silicon on foreign substrate is an attractive way to realize cheap and efficient photovoltaic devices. In this paper we will compare epitaxial growth of silicon thin film on double porous sacrificial layers obtained by liquid or vapor phase epitaxy (LPE or VPE). Porous silicon is formed by electrochemical anodisation of monocrystalline silicon in a HF/ethanol solution. VPE is achieved in an atmospheric pressure chemical vapor deposition (APCVD) reactor under H2 atmosphere. Growth rate is in between 0.5-3 ?m/min. LPE is realised in a graphite sliding boat using indium or tin as solvent. Growth rate is in the range 0.1-1 ?m/min depending on the temperature, the cooling rate and the solvent. We discuss the substrate orientation, temperature, growth rate, layer homogeneity and electrical properties of the epilayers for both growing techniques. Diffusion length and mobility are measured respectively with LBIC and Hall effect technique. The values obtained for p-type (?>100 V/cm2/s and Ln>100 ?m) allows the realisation of solar cell using interdigitated technology on the top of this layer, which is detached and transferred onto mullite substrate

  13. 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.

  14. Phosphorus diffusion gettering process of multicrystalline silicon using a sacrificial porous silicon layer

    Science.gov (United States)

    Lotfi, Derbali; Hatem, Ezzaouia

    2012-07-01

    The aims of this work are to getter undesirable impurities from low-cost multicrystalline silicon (mc-Si) wafers and then enhance their electronic properties. We used an efficient process which consists of applying phosphorus diffusion into a sacrificial porous silicon (PS) layer in which the gettered impurities have been trapped after the heat treatment. As we have expected, after removing the phosphorus-rich PS layer, the electrical properties of the mc-Si wafers were significantly improved. The PS layers, realized on both sides of the mc-Si substrates, were formed by the stain-etching technique. The phosphorus treatment was achieved using a liquid POCl3-based source on both sides of the mc-Si wafers. The realized phosphorus/PS/Si/PS/phosphorus structures were annealed at a temperature ranging between 700°C and 950°C under a controlled O2 atmosphere, which allows phosphorus to diffuse throughout the PS layers and to getter eventual metal impurities towards the phosphorus-doped PS layer. The effect of this gettering procedure was investigated by means of internal quantum efficiency and the dark current-voltage ( I- V) characteristics. The minority carrier lifetime measurements were made using a WTC-120 photoconductance lifetime tester. The serial resistance and the shunt resistance carried out from the dark I- V curves confirm this gettering-related solar cell improvement. It has been shown that the photovoltaic parameters of the gettered silicon solar cells were improved with regard to the ungettered one, which proves the beneficial effect of this gettering process on the conversion efficiency of the multicrystalline silicon solar cells.

  15. Phosphorus diffusion gettering process of multicrystalline silicon using a sacrificial porous silicon layer.

    Science.gov (United States)

    Lotfi, Derbali; Hatem, Ezzaouia

    2012-01-01

    The aims of this work are to getter undesirable impurities from low-cost multicrystalline silicon (mc-Si) wafers and then enhance their electronic properties. We used an efficient process which consists of applying phosphorus diffusion into a sacrificial porous silicon (PS) layer in which the gettered impurities have been trapped after the heat treatment. As we have expected, after removing the phosphorus-rich PS layer, the electrical properties of the mc-Si wafers were significantly improved. The PS layers, realized on both sides of the mc-Si substrates, were formed by the stain-etching technique. The phosphorus treatment was achieved using a liquid POCl3-based source on both sides of the mc-Si wafers. The realized phosphorus/PS/Si/PS/phosphorus structures were annealed at a temperature ranging between 700°C and 950°C under a controlled O2 atmosphere, which allows phosphorus to diffuse throughout the PS layers and to getter eventual metal impurities towards the phosphorus-doped PS layer. The effect of this gettering procedure was investigated by means of internal quantum efficiency and the dark current-voltage (I-V) characteristics. The minority carrier lifetime measurements were made using a WTC-120 photoconductance lifetime tester. The serial resistance and the shunt resistance carried out from the dark I-V curves confirm this gettering-related solar cell improvement. It has been shown that the photovoltaic parameters of the gettered silicon solar cells were improved with regard to the ungettered one, which proves the beneficial effect of this gettering process on the conversion efficiency of the multicrystalline silicon solar cells. PMID:22846070

  16. 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.

  17. 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)

  18. Fabrication of low-temperature co-fired ceramics micro-fluidic devices using sacrificial carbon layers

    OpenAIRE

    Birol, Hansu; Maeder, Thomas; Jacq, Caroline; Straessler, Sigfrid; Ryser, Peter

    2005-01-01

    Ease of fabrication and design flexibility are two attractive features of low temperature co-fired ceramics (LTCC) technology for fabrication of complex micro-fluidic devices. Such structures are designed and processed using different shaping methods, the extent and complexity of which depends on the final device specifications (dimensions, mechanical and functional properties). In this work, we propose a sacrificial layer method based on carbon-black paste, which burns out during the LTCC fi...

  19. Further work on sodium borates as sacrificial materials for a core-catcher

    International Nuclear Information System (INIS)

    Sodium borates are suitable low melting point sacrificial materials for a core-catcher of a fast reactor. Concept, design and initial development work have been described previously. Here we report on the measurements of density, volumetric thermal expansion coefficients and viscosity of borax and sodium metaborate, pure and with various percentages of dissolved UO2. The density of these molten salts was measured with the buoyancy method in the temperature range 850 - 13000C, while the viscosity was measured in the temperature range 700 - 12500C with a Haake viscosity balance. Simulation experiments with low melting point materials were performed to investigate the ratio of the downward to sideward melt velocity. The results of these experiments show that this ratio is equal to 0.34 for a solid to liquid density ratio rho = 1.66. For the real borax core-catcher rho = 4 and this would correspond to a velocity ratio of about one

  20. Electric double layer effect in a nano-scale SiO2 sacrificial layer etching process and its application in nanowire fabrication

    International Nuclear Information System (INIS)

    Process controllability has become one of the key factors for utilizing micro-scale processes in nanofabrication. Sacrificial layer technology especially should be carefully handled to avoid excessive etching of nano-scale device structures. In this work, the etching behavior of a buffered HF (BHF) solution for thermally-grown silicon dioxide sacrificial layers with thicknesses in the range of 22 to 112.7 nm was characterized. For the first time, accelerated limiting of etching was reported for sub-50 nm layers. However, for thicker ones (more than 50 nm), almost constant rate isotropic etching was observed. A detailed discussion revealed that the conventional diffusion-induced etching model was no longer valid in such a minute structure, and the electric double layer (EDL) effect instead, was likely to dominate. Simulation was carried out to investigate the influence of the electric potential generated by an interfacial charge layer upon reactive ions in the etchant, which was proved to be consistent with the experimental results. By using such nano-scale sacrificial layer technology, combined with anisotropic silicon etching, cost-effective and stable production of silicon nanowires (SiNWs) was accomplished, with a uniform width down to 100 nm, respectively. Reliable electrical connection was also achieved by smooth transitions from the nanowire to single crystal silicon electrodes, which further confirmed the potential of this highly controllable process

  1. 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.

  2. Sodium Exposure Tests on Limestone Concrete Used as Sacrificial Protection Layer in FBR

    International Nuclear Information System (INIS)

    Hot sodium coming in contact with structural concrete in case of sodium leak in FBR system cause damage as a result of thermo-chemical attack by burning sodium. In addition, release of free and bound water from concrete leads to generation of hydrogen gas, which is explosive in nature. Hence limestone concrete, as sacrificial layer on the structural concrete in FBR, needs to be qualified. Four concrete blocks of dimension 600 mm x 600 mm x 300 mm with 300 mm x 300 mm x 150 mm cavity were cast and subjected to controlled sodium exposure tests. They have composition of ordinary portland cement, water, fine and coarse aggregate of limestone in the ratio of 1: 0.58: 2.547: 3.817. These blocks were subjected to preliminary inspection by ultrasonic pulse velocity technique and rebound hammer tests. Each block was exposed for 30 minutes to about 12 kg of liquid sodium (? 120 mm liquid column) at 550 deg. C in open air, after which sodium was sucked back from the cavity of the concrete block into a sodium tank. On-line temperature monitoring was carried out at strategic locations of sodium pool and concrete block. After removing sodium from the cavity and cleaning the surfaces, rebound hammer testing was carried out on each concrete block at the same locations where data were taken earlier at pre-exposed stage. The statistical analysis of rebound hammer data revealed that one of the concrete block alone has undergone damage to the extent of 16%. The loss of mass occurred foent of 16%. The loss of mass occurred for all the four blocks varied from 0.6 to 2.4% due to release of water during the test duration. Chemical analysis of sodium in concrete samples collected from cavity floor of each block helped in generation of depth profiles of sodium monoxide concentration for each block. From this it is concluded that a bulk penetration of sodium up to 30 mm depth has taken place. However it was also observed that at few local spots, sodium penetrated into concrete up to 50 mm. Cylindrical core samples of 50 mm x 150 mm long were obtained from the exposed cavity and tested for compressive strength and longitudinal ultrasonic pulse velocity (UPV). These are compared with core samples obtained from concrete cubes used as standard reference. The average reduction in UPV and compressive strength were 7% and 29% respectively indicating marginal degradation in mechanical properties of sodium-exposed concrete. (authors)

  3. Sugar-mediated disassembly of mucin/lectin multilayers and their use as pH-Tolerant, on-demand sacrificial layers.

    Science.gov (United States)

    Polak, Roberta; Crouzier, Thomas; Lim, Rosanna M; Ribbeck, Katharina; Beppu, Marisa M; Pitombo, Ronaldo N M; Cohen, Robert E; Rubner, Michael F

    2014-08-11

    The layer-by-layer (LbL) assembly of thin films on surfaces has proven to be an extremely useful technology for uses ranging from optics to biomedical applications. Releasing these films from the substrate to generate so-called free-standing multilayer films opens a new set of applications. Current approaches to generating such materials are limited because they can be cytotoxic, difficult to scale up, or have undesirable side reactions on the material. In this work, a new sacrificial thin film system capable of chemically triggered dissolution at physiological pH of 7.4 is described. The film was created through LbL assembly of bovine submaxillary mucin (BSM) and the lectin jacalin (JAC) for a (BSM/JAC) multilayer system, which remains stable over a wide pH range (pH 3-9) and at high ionic strength (up to 5 M NaCl). This stability allows for subsequent LbL assembly of additional films in a variety of conditions, which could be released from the substrate by incubation in the presence of a competitive inhibitor sugar, melibiose, which selectively disassembles the (BSM/JAC) section of the film. This novel multilayer system was then applied to generate free-standing, 7 ?m diameter, circular ultrathin films, which can be attached to a cell surface as a "backpack". A critical thickness of about 100 nm for the (BSM/JAC) film was required to release the backpacks from the glass substrate, after incubation in melibiose solution at 37 °C for 1 h. Upon their release, backpacks were subsequently attached to murine monocytes without cytotoxicity, thereby demonstrating the compatibility of this mucin-based release system with living cells. PMID:24964165

  4. Comparison of solvent and sacrificial volume-material-based lamination processes of low-temperature co-fired ceramics tapes

    International Nuclear Information System (INIS)

    The lamination process determines the quality of low temperature co-fired ceramics (LTCC) based spatial structures. This paper compares two methods of the microchannel fabrication process in zero-shrinkage LTCC substrates. The first one is based on a two-step lamination process and uses various sacrificial volume materials (SVM). The second one is based on the cold chemical lamination (CCL) process. On the one hand, the SVM gives the possibility of decreasing the deformation of the three-dimensional (3D) structures during the lamination process. The channel volume is filled with a special fugitive material. It protects the spatial structure from deformation during lamination, and evaporates completely during the co-firing process. The bonding quality and strength depend strongly on the fugitive phase type. On the other hand, the CCL is a solvent-based method. It is another alternative for bonding of green ceramic tapes. A special liquid agent is screen printed on the green tape, which melts the tape surface. Then the tapes are stacked and compressed at room temperature by a printing roll. The influence of each method on the microchannel geometry is analyzed in this paper. The resulting structures' bonding quality and mechanical properties are examined by a scanning electron microscope (SEM)

  5. High-reflectivity GaN/air vertical distributed Bragg reflectors fabricated by wet etching of sacrificial AlInN layers

    International Nuclear Information System (INIS)

    Microstructures containing GaN/air distributed Bragg reflector (DBR) regions were fabricated by a selective wet etch to remove sacrificial AlInN layers from GaN–AlInN multilayers. The epitaxial multilayers were grown on free-standing GaN substrates, and contained AlInN essentially lattice matched with GaN in order to minimize strain. Two geometries were defined for study by standard lithographic techniques and dry etching: cylindrical pillars and doubly anchored rectangular bridges. Microreflectivity spectra were recorded from the air-gap DBRs, and indicated peak reflectivities exceeding 70% for a typical 3-period microbridge. These values are likely to be limited by the small scale of the features in comparison with the measurement spot. The stopband in this case was centred at 409 nm, and the reflectivity exceeded 90% of the maximum over 73 nm. Simulations of reflectance spectra, including iterations to layer thicknesses, gave insight into the tolerances achievable in processing, in particular indicating bounds on the parasitic removal of GaN layers during wet etching. Air-gap nitride DBRs as described can be further developed in various ways, including adaptation for electrostatic tuning, incorporation into microcavities, and integration with active emitters. (rapid communication)

  6. Nano- and micro-sized rare-earth carbonates and their use as precursors and sacrificial templates for the synthesis of new innovative materials.

    Science.gov (United States)

    Kaczmarek, Anna M; Van Hecke, Kristof; Van Deun, Rik

    2015-04-10

    This review focuses on rare-earth carbonate materials of nano- and micro-size. It discusses in depth the different types of rare-earth carbonate compounds, diverse synthetic approaches and possibilities for chemical tuning of the size, shape and morphology. The interesting luminescence properties of lanthanide doped rare-earth carbonates and their potential applications for example as efficient white light sources and biolabels are reviewed. Additionally the use of these materials as precursors for the synthesis of nano-/micro-sized oxides, and their application as sacrificial templates for morphology-controlled synthesis of other materials such as YVO4, LaF3, NaYF4 and others is overviewed. PMID:25714401

  7. Hot sodium-triggered thermo-chemical degradation of concrete aggregates in the sodium resistant sacrificial layers of 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); Ramasamy, R. [Department of Ocean Engineering, IIT Madras, Chennai (India); Parida, F.C. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2013-12-15

    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.

  8. 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

  9. Surface imprinting on nano-TiO2 as sacrificial material for the preparation of hollow chlorogenic acid imprinted polymer and its recognition behavior

    International Nuclear Information System (INIS)

    Highlights: ? Used surface imprinting technique with nano-TiO2 as sacrificial support material. ? Improved adsorption capability of the H-MIP1 compared with the previous work. ? Excellent mass transfer dynamics for the H-MIP1. ? Investigated adsorption thermodynamic of the H-MIP1. - Abstract: Surface imprinting chlorogenic acid (CGA) on nano-TiO2 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 witThis 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.

  10. 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

  11. 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.

  12. 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 ...

  13. 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 experimebottom 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

  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. Method to fabricate layered material compositions

    Science.gov (United States)

    Fleming, James G.; Lin, Shawn-Yu

    2004-11-02

    A new class of processes suited to the fabrication of layered material compositions is disclosed. Layered material compositions are typically three-dimensional structures which can be decomposed into a stack of structured layers. The best known examples are the photonic lattices. The present invention combines the characteristic features of photolithography and chemical-mechanical polishing to permit the direct and facile fabrication of, e.g., photonic lattices having photonic bandgaps in the 0.1-20.mu. spectral range.

  16. Atomic Layer Deposition-Based Synthesis of Photoactive TiO2 Nanoparticle Chains by Using Carbon Nanotubes as Sacrificial Templates

    OpenAIRE

    Shaoren Deng; Sammy W. Verbruggen; Zhanbing He; Daire J Cott; Philippe M. Vereecken; Johan. A. Martens; Sara Bals; Silvia Lenaerts; Christophe Detavernier

    2014-01-01

    Highly ordered and self supported anatase TiO2 nanoparticle chains were fabricated by calcining conformally TiO2 coated multi-walled carbon nanotubes (MWCNTs). During annealing, the thin tubular TiO2 coating that was deposited onto the MWCNTs by atomic layer deposition (ALD) was transformed into chains of TiO2 nanoparticles (~12 nm diameter) with an ultrahigh surface area (137 cm2 per cm2 of substrate), while at the same time the carbon from the MWCNTs was removed. Photocata...

  17. Ultrasonic classification of thin layers within multi-layered materials

    International Nuclear Information System (INIS)

    Methods for non-destructive inspection of layered materials are becoming more and more popular as a way of assuring product integrity and quality. In this paper, we present a model-based technique using ultrasonic measurements for classification of thin bonding layers within three-layered materials. This could be, for example, an adhesive bond between two thin plates, where the integrity of the bonding layer needs to be evaluated. The method is based on a model of the wave propagation of pulse-echo ultrasound that first reduces the measured data to a few parameters for each measured point. The model parameters are then fed into a statistical classifier that assigns the bonding layer to one of a set of predefined classes. In this paper, two glass plates are bonded together with construction silicone, and the classifiers are trained to determine if the bonding layer is intact or if it contains regions of air or water. Two different classification methods are evaluated: nominal logistic regression and discriminant analysis. The former is slightly more computationally demanding but, as the results show, it performs better when the model parameters cannot be assumed to belong to a multivariate Gaussian distribution. The performance of the classifiers is evaluated using both simulations and real measurements

  18. Preparation and application of minerals-based sacrificial pastes for fabrication of LTCC structures

    OpenAIRE

    Birol, Hansu; Maeder, Thomas; Ryser, Peter

    2006-01-01

    This work presents the preliminary results on application of mineral sacrificial layer that is prepared to structure LTCC (low temperature co-fired ceramic). The proposed method suggests utilization of a sacrificial paste, which remains "permanent" during firing and later removed by chemical dissolution, thus providing an effective support throughout the firing. The paste is based on a mixture of B2O3 and alkaline earth oxides and screen-printed on an LTCC sheet that is laminated with additio...

  19. 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.

  20. Thin film of Poly(acrylic acid-co-allyl acrylate as a Sacrificial Protective Layer for Hydrophilic Self Cleaning Glass

    Directory of Open Access Journals (Sweden)

    J?nis Lejnieks

    2010-05-01

    Full Text Available Poly(acrylic acid-co-allyl acrylate statistical copolymers were synthesized in a controlled manner in two steps: first tert.butyl acrylate and allyl acrylate were polymerized via atom transfer radical polymerization (ATRP and afterwords the tert.butyl protective groups were removed via hydrolysis. Samples of self cleaning glass (SCG were coated with thin films of poly(acrylic acid-co-allyl acrylate and cross-linked afterwards by UV irradiation (in the presence of a photoinitiator and an accelerator. Solution cast thin films were transparent and homogeneous before and after UV cross-linking. The irradiated samples were found to be hydrophilic (? < 20° and water insoluble. The coating prevented the spontaneous hydrophobization of the SCG by residual silicon exhaled from the sealing material. The TiO2 photocatalyst that covers the glass surface was found to strip the protective coating. The rate of the photooxidation process was measured by IR spectroscopy. The real field performance of the protective coating was also tested.

  1. Bi-layer excitons in two-dimensional layered materials

    Science.gov (United States)

    Neupane, Mahesh; Yin, Gen; Wickramaratne, Darshana; Lake, Roger

    2013-03-01

    Following the prediction of exciton condensation in closely spaced two-dimensional electron-hole bilayer systems, there has been a sustained theoretical and experimental investigation of this condensation phase in coupled quantum well material systems. The electron-hole pairs are bound by the interlayer Coulomb interaction, which is tuned by electrostatic gating of the charge density. The magnitude of this interaction is determined by the binding energy between the electron and the hole. Improvements in the exciton binding energy can be achieved by an appropriate choice of materials. The family of van der Walle materials is considered in this study, and the effect of material choice and insulating layer thickness on the excitonic properties will be discussed and compared to experimental investigations using traditional GaAs-AlGaAs coupled quantum wells. Following the prediction of exciton condensation in closely spaced two-dimensional electron-hole bilayer systems, there has been a sustained theoretical and experimental investigation of this condensation phase in coupled quantum well material systems. The electron-hole pairs are bound by the interlayer Coulomb interaction, which is tuned by electrostatic gating of the charge density. The magnitude of this interaction is determined by the binding energy between the electron and the hole. Improvements in the exciton binding energy can be achieved by an appropriate choice of materials. The family of van der Walle materials is considered in this study, and the effect of material choice and insulating layer thickness on the excitonic properties will be discussed and compared to experimental investigations using traditional GaAs-AlGaAs coupled quantum wells. Microelectronics Advanced Research Corporation Focus Center on Nano Materials (FENA)

  2. Preface "Layer silicate materials and clays"

    OpenAIRE

    G. Valdre

    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 sc...

  3. Layered zeolite materials and methods related thereto

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Acoustic cloaking using layered pentamode materials.

    Science.gov (United States)

    Scandrett, Clyde L; Boisvert, Jeffrey E; Howarth, Thomas R

    2010-05-01

    While receiving less attention in the literature than electromagnetic cloaking, theoretical efforts to define and create acoustic cloaks based upon mimicking coordinate transformations through use of metamaterials is of interest. The present work extends recent analysis of Norris [Proc. R. Soc. London, Ser. A 464, 2411-2434 (2008)] by considering a range of cloaks, from those comprised of fluid layers which are isotropic in bulk moduli with anisotropic density to those having anisotropic bulk moduli and isotropic density. In all but pure inertial varieties, fluid layers comprising the cloaks are pentamode materials governed by a special scalar acoustic equation for pseudopressure derived by Norris. In most cases presented, material properties of the fluid/pentamode layers are based upon target values specified by continuously varying properties resulting from theoretical coordinate transformations geared to minimize scattered pressure limited by realistic goals. The present work analyzes such cloaks for the specific case of plane wave scattering from an acoustically hard sphere. An initial exploration of the parameter space defining such cloaks (for example, material properties of its constituent layers, and operating frequency) is undertaken with a view toward "optimal" design. PMID:21117736

  5. 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)

  6. Harmonic generation in 2D layered materials

    Science.gov (United States)

    Janisch, Corey; Ma, Ding; Mehta, Nikhil; Laura-Elias, Ana; Perea-Lopez, Nestor; Terrones, Mauricio; Liu, Zhiwen

    2014-09-01

    Two-Dimensional (2D) layered materials have garnered interest due to their novel optical and electronic properties. In this work, we investigate Second Harmonic Generation (SHG) in Tungsten Disulfide (WS2) monolayers grown on SiO2/Si substrates and suspended on a transmission electron microscopy grid; we find an unusually large second order susceptibility, which is nearly three orders of magnitude larger than common nonlinear crystals. We have also developed a Green's function based formalism to model the harmonic generation from a 2D layer .

  7. Electrically actuated sacrificial membranes for valving in microsystems

    International Nuclear Information System (INIS)

    Valving is essential to microflow circuits and networks in microsystem technology. Many different types of valves have been designed and fabricated. Membranes of sacrificial material have already been designed for one-shot valving. However, the new design proposed here, based on sacrificial micro-membranes with embedded electrodes, has the advantages of being efficient, easily controllable and requiring very low energy levels. We have shown that a 100 µm × 100 µm × 500 nm Si3N4 membrane with a platinum electrode can be actuated to break up with an energy input of only 6 µJ, during an actuation time of 200 µs. At rest, in the absence of actuation, such membranes can withstand a pressure of 1 bar. The goal of the development of such membranes is to hydrodynamically connect, one by one, a series of initially isolated micro-chambers implemented in a silicon chip.

  8. Electrochemistry : SacrificialAnode (10 Variations)

    Science.gov (United States)

    The following electrochemical data may be helpful in answering the question below. One method for protecting metals against corrosion is to connect the metal directly to a "sacrificial anode". This is the method used to protect pipelines and ships hulls. Which of the following metals would you consider the best candidate for a sacrificial anode for a ship's hull? The hull is steel (which is mostly iron).

  9. Mixed layers in copper based superconducting materials

    International Nuclear Information System (INIS)

    Recently discovered series of high Tc superconductors, characterized by the experience of two types of cations within the same layer, are presented. The first family concerns the mercury based cuprates, Hg1-xMxA2Cam-1CumO2m+2+?, with A = Ba and/or Sr, which exhibit structures closely related to that of the thallium cuprates TlBa2Cam-1CumO2m+3. They differ from the thallium cuprates by a high oxygen deficiency at the level of the mercury layer. It is shown that cations such as M = Cu, Pb, Tl, Bi, Ce, Pr, Cr, V, Mo, W, Ti, Sr, Ca,... can partially substitute for mercury ions, stabilizing the structures. The cationic composition of the layer depends indeed on the nature of the M cation but also on that of the alkaline earth A. For given A and M cations, the x value remains unchanged even when the number of copper layers varies. M and Hg cations are either statistically distributed over the same site or ordered. Different types of ordering have been detected. Another way of generating mixed layers is to shear periodically the structure, leading to the formation of the so called 'collapsed phase'. In the collapsed bismuth cuprates, bismuth and copper segments, a few octahedra long, alternate in strongly waving layers. In the collapsed oxy-carbonates, carbonate groups and M cations are ordered within the intermediate layer so that they can be simply described from o that they can be simply described from a partial and ordered substitution of carbon for Hg, Tl, Bi and other M cations building the intermediate layer. The oxy-carbo-nitrates (Y1-xCax)nBa2n-1(C,N)O3O7n-3 can also be described as an ordered substitution of carbon for copper in the 123 matrix. The different families of superconducting materials with are generated by such mechanisms are described as well as the way the different species are distributed within the mixed layers. Their influence on the physical properties are discussed. (authors). 73 refs., 21 figs., 3 tabs

  10. 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.

  11. Layered Atom Arrangements in Complex Materials

    Energy Technology Data Exchange (ETDEWEB)

    K.E. Sikafus; R.W.Grimes; S.M.Corish; A.R. Cleave; M.Tang; C.R.Stanek; B.P. Uberuaga; J.A.Valdez

    2005-04-15

    In this report, we develop an atom layer stacking model to describe systematically the crystal structures of complex materials. To illustrate the concepts, we consider a sequence of oxide compounds in which the metal cations progress in oxidation state from monovalent (M{sup 1+}) to tetravalent (M{sup 4+}). We use concepts relating to geometric subdivisions of a triangular atom net to describe the layered atom patterns in these compounds (concepts originally proposed by Shuichi Iida). We demonstrate that as a function of increasing oxidation state (from M{sup 1+} to M{sup 4+}), the layer stacking motifs used to generate each successive structure (specifically, motifs along a 3 symmetry axis), progress through the following sequence: MMO, MO, M{sub r}O, MO{sub r/s}O{sub u/v}, MOO (where M and O represent fully dense triangular atom nets and r/s and u/v are fractions used to describe partially filled triangular atom nets). We also develop complete crystallographic descriptions for the compounds in our oxidation sequence using trigonal space group R{bar 3}.

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

    OpenAIRE

    Lieou, Charles K. C.; Elbanna, Ahmed E.; 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 hidde...

  13. Thin layer activation for materials analysis

    International Nuclear Information System (INIS)

    The basic physics underlying thin layer activation, and its relevance to industrial problems are briefly reviewed. The service component or test material is activated with an ion beam, e.g. of protons, to produce a minute quantity of radioactive atoms in a thin surface layer. In a typical example the wear of a cylinder liner, which has been activated, is followed by measuring the loss of activity. Other examples are given. Developments of the process are: (i) multiple activation profiles which can be used to extract more information on the characteristics of the surface loss process particularly when the loss is non-uniform; (ii) a newly-established process called non-elastic recoil implantation which can be used even on radiation sensitive materials; (iii) the possibility for activation of truly immovable objects through the implantation of fission fragments; and (iv) the application of ion beam activation for the analysis and profiling of the light elements in the near surface. These developments are discussed. (U.K.)

  14. Sacrificial Plastic Mold With Electroplatable Base

    Science.gov (United States)

    Domeier, Linda A. (Danville, CA); Hruby, Jill M. (Livermore, CA); Morales, Alfredo M. (Livermore, CA)

    2005-08-16

    A sacrificial plastic mold having an electroplatable backing is provided. One embodiment consists of the infusion of a softened or molten thermoplastic through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale molding tool contacting the porous metal substrate. Upon demolding, the porous metal substrate will be embedded within the thermoplastic and will project a plastic structure with features determined by the mold tool. This plastic structure, in turn, provides a sacrificial plastic mold mechanically bonded to the porous metal substrate which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved to leave the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

  15. Alternating Current Corrosion of Aluminium Sacrificial Anodes

    OpenAIRE

    Forthun, Kari

    2013-01-01

    Direct Electric Heating (DEH) is applied to subsea oil production and transmission pipelines to prevent freezing of hydrates as wax during productions shut downs. To prevent clogging, the pipes are heated by application of alternating current (AC) voltage. As a result, a risk for AC corrosion is introduced, which is the motivation and subject of this thesis. The steel pipes are coated and applied conventional cathodic protection (CP) by use of AlZnIn sacrificial anodes. The present work focus...

  16. Nonlinear Dynamic Properties of Layered Composite Materials

    International Nuclear Information System (INIS)

    We present an application of the asymptotic homogenization method to study wave propagation in a one-dimensional composite material consisting of a matrix material and coated inclusions. Physical nonlinearity is taken into account by considering the composite's components as a Murnaghan material, structural nonlinearity is caused by the bonding condition between the components.

  17. 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

  18. Examples of material solutions in bimetallic layered castings

    OpenAIRE

    S. Tenerowicz; M. Cholewa; T. Wróbela

    2011-01-01

    In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer). The bearing part of bimetallic layered casting is typical foundry material i.e. pearlitic grey cast iron, whereas working part (layer) is depending on accepted variant plates of alloy steels sort X6Cr13, X12Cr13, X10CrNi18-8 and...

  19. Magnetostatic waves in layered materials and devices:

    OpenAIRE

    Khalili Amiri, P.; Rejaei, B.

    2006-01-01

    Magnetostatic wave propagation in multilayers of ferro-/ferrimagnetic and nonmagnetic, dielectric slabs is investigated using an effective medium theory and the transfer matrix method. The propagation in multilayers with antiparallel directions of magnetization is analyzed, in particular. Antiparallel multilayers support (overall) bulk waves at frequencies much higher than single layers or parallel-magnetization structures. As possible applications of these multilayers, waveguides and resonat...

  20. 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.

  1. 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.

  2. Surface density of states of layered f-electron materials

    Science.gov (United States)

    Peters, Robert; Kawakami, Norio

    2014-01-01

    We theoretically analyze the surface density of states of heavy fermion materials such as CeCoIn5. Recent experimental progress has made it possible to locally probe the formation of heavy quasiparticles in these systems via scanning tunneling microscopy, in which strongly temperature-dependent resonances at the Fermi energy have been observed. The shape of these resonances varies depending on the surface layer, i.e., if cerium or cobalt terminates the sample. We clarify the microscopic origin of this difference by taking into account the layered structure of the material. Our simple model explains all the characteristic properties observed experimentally, such as a layer-dependent shape of the resonance at the Fermi energy, displaying a hybridization gap for the cerium layer and a peak or dip structure for the other layers. Our proposal resolves the seemingly unphysical assumptions in the preceding analysis based on the two-channel cotunneling model.

  3. Examples of material solutions in bimetallic layered castings

    Directory of Open Access Journals (Sweden)

    S. Tenerowicz

    2011-07-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. pearlitic grey cast iron, whereas working part (layer is depending on accepted variant plates of alloy steels sort X6Cr13, X12Cr13, X10CrNi18-8 and X2CrNiMoN22-5-3. The ratio of thickness between bearing and working part is 8:1. The verification of the bimetallic layered castings was evaluated on the basis of ultrasonic NDT (non-destructive testing, structure and macro- and microhardness researches.

  4. 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

  5. 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.

  6. 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...

  7. 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 surfaccular, 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

  8. Thermodynamics of sacrificial deoxidation of refractory metals

    International Nuclear Information System (INIS)

    Sacrificial deoxidation via suboxide evaporation at high temperature and vacuum is one of the most important techniques for the purification of many refractory metals. A theoretical thermodynamic approach has been attempted to assess and examine the deoxidation tendencies of refractory metals of groups IV and V. Based on the thermodynamic data available for gaseous suboxides and reported or estimated values of oxygen activities in the metals, vapour pressures of suboxides have been calculated and plotted as a function of temperature and oxygen content of the metal. From these data it has been possible to estimate: (1) the extent of deoxidation, (2) the vaporization loss of metal during deoxidation, and (3) the rate of deoxidation. Calculations have also been made for ternary systems such as Nb-Zr-O and Ta-Hf-O. The calculated values are compared with the reported values based on the experimental observations. (author)

  9. 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)

  10. The effect of gamma irradiation on few layered graphene materials

    OpenAIRE

    Anso?n Casaos, Alejandro; Pue?rtolas, J. A.; Pascual, F. J.; Herna?ndez-ferrer, J.; Castell, Pere; Benito, Ana M.; Maser, Wolfgang K.; Marti?nez, M. Teresa

    2014-01-01

    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...

  11. CVD COATING OF CERAMIC LAYERS ON CERAMIC CUTTING TOOL MATERIALS

    OpenAIRE

    Porat, R.

    1991-01-01

    When forming cutting tool materials based on ceramic components, one must take into considration the combination of wear resistance and mechanical properties which can withstand unfavorable cutting conditions at the same time maintaining high strength and fracture toughness. Ceramic cutting tools which are designed for machining at high cutting speeds and which have high strength and fracture toughness can be formed by applying a thin layer of ceramic materials on the substrate in order to in...

  12. 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

  13. 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

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

    Science.gov (United States)

    Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.

    2013-03-01

    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 of energy dissipation. One example of occurrence of sacrificial bonds and hidden length is in the polymeric glue connection between collagen fibrils in animal bone. In this talk, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the revelation of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation, at the mean-field level, allowing for the number of bonds and hidden lengths to take up non-integer values between successive, discrete bond-breakage events. 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.

  15. 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.

  16. Investigation into conditions of producing two-layer materials with the surface layer of titanium carbide-steel

    International Nuclear Information System (INIS)

    The possibility is studied of the production of iron-based twin-layer materials with addition of 1, 2, 3% Cu having a surface layer made up of titanium carbide - steel through the method of the simultaneous pressing and sintering together with the hot-pressing of the sintered layer to the sintered basic material. The strength of the layer coupling increases with a higher copper content and lower pressing force applied to the basic material. Thermal treatment enhances the layer hardness and practically does not effect on the layer coupling

  17. 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.

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

    Science.gov (United States)

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

    2014-09-16

    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.

  19. Computational homogenization of material layers with micromorphic mesostructure

    OpenAIRE

    Hirschberger, Claudia Britta; Sukumar, Natarajan; Steinmann, Paul

    2008-01-01

    Abstract In this paper, a multiscale approach to capture the behaviour of material layers that possess a micromorphic mesostructure is presented. To this end, we seek to obtain a macroscopic traction-separation law based on the underlying meso- and micro-structure. At the macro level, a cohesive interface description is used, whereas the underlying mesostructure is resolved by a micromorphic representative volume element. This generalised continuum theory is p...

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

    OpenAIRE

    Joe H. Satcher; John F. Poco; Theodore F. Baumann; Pellin, Michael J.; John N. Hryn; Ulrich Welp; James P. Birrell; H. Hau Wang; Han, Catherine Y.; Guang Xiong; Elam, Jeffrey W.

    2006-01-01

    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 memb...

  1. 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.

  2. Elastic measurements of layered nanocomposite materials by Brillouin spectroscopy

    Science.gov (United States)

    Lefeuvre; Kolosov; Every; Briggs; Tsukahara

    2000-03-01

    Surface Brillouin spectroscopy makes it possible to measure surface elastic wave propagation parameters at frequencies up to 20 GHz or more. This enables us to measure the elastic properties of surface layers only a small fraction of a micrometre thick. The wavelength and incident angle of the light determine the wavenumber of surface elastic waves (SAW) that scatter the light inelastically, and their frequency can be found by measuring the change in wavelength of the scattered light. By analysing the elastic wave modes present in the surface, the elastic properties can be deduced. We have used this technique to measure the elastic properties of layered nanocomposite materials, which are widely used in the packaging industry. 12 microns polymer films (PET) were coated with glass oxide layers of thickness as little as 25 nm, to give transparent nanocomposite structures with excellent gas barrier properties. In order to understand and model the behaviour of these films under deformation, it is necessary to determine the elastic properties of the different layers. Evaluation of the elastic properties presents several challenges. First, the oxide layers are much thinner than the wavelengths of the surface phonons in surface Brillouin spectroscopy (and hence the depth probed), which usually lie in the range 250-500 nm. The anisotropic elastic properties of the PET substrate must therefore be measured accurately, and this can be done using bulk Brillouin spectroscopy. Second, a thin layer of metal (usually 10-20 nm) must be deposited on the glass surface so that the surface phonons scatter the light effectively. The elastic properties of the glass layer can then be deduced from surface Brillouin spectroscopy measurements, by simulating the surface wave modes of the metal/glass/polymer composite, and adjusting the parameters to give the best fit. In this way it is possible to observe how the properties of the glass vary as a function of thickness, and in turn to understand how to improve systematically the properties under deformation. PMID:10829705

  3. 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 ...

  4. 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

  5. Evaluation of layer-by-layer graphene structures as supercapacitor electrode materials

    Science.gov (United States)

    Zang, Xiaobei; Li, Peixu; Chen, Qiao; Wang, Kunlin; Wei, Jinquan; Wu, Dehai; Zhu, Hongwei

    2014-01-01

    Very less attention has been paid recently to the electrochemical properties of graphene films with intrinsic flat structure prepared by chemical vapor deposition (CVD). In this work, button supercapacitors were fabricated using ionic liquid as electrolytes and layer-by-layer graphene structures as electrodes. The specific capacitances of the supercapacitors increased with the increase of layer number. The areal specific capacitance of ten-layer graphene supercapacitor was 0.29 mF/cm2 at the scan rate of 50 mV/s, which was about three times of that of monolayer graphene supercapacitor (0.1 mF/cm2). The sandwiched multi-layer structures with oxide deposition further improved the device performance. However, the polycrystalline nature of CVD-grown graphene films introduced structural instability during charge-discharge process, resulting in degraded capacitive performance and cycling stability. Our results suggest that graphene films with intrinsic "in-plane" structure might not be ideal candidates for electrode materials.

  6. Gamma radiation transport and scattering in layers of material

    International Nuclear Information System (INIS)

    A program was written allowing to model, using the Monte Carlo method, gamma radiation transport through homogeneous and heterogeneous material under given geometrical conditions. Modelling all basic types of interactions it was found that coherent scattering has great infiuence on the value of albedo. Further computations showed that the dependence on atomic number Z of the probability of impingement of backscattered photons on the detector, is a compticated curve with maxima in every group of the periodical table. The shape of the curve is influenced by the dependence of albedo on Z. The said program was used to compute the probability of gamma backscattering from layers of material with a thickness less than the saturation thickness. Also computed were the values of gamma radiation buildup factors, and the configuration was designed for measuring material density using gamma radiation backscattering under different measuring conditions. (M.D.)

  7. 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.??????? ???????????? ????????????????? ?????????? ?????? ? ???????????? ????????????? ?????????? ???????????????? ????????? ????????, ? ????????? ????????? ???????. ??????????? ???? ?????? ?????????? ? ???????? ?? ???? ?????????? ??????????? ??????????????? ?????????, ? ?.?. ???????? ???????? ????????? ???? ???????. ? ??????????? ?????????????? ??????? ???????? ?????????? ?? ??????? ?????????? ???????? ????????? ???????????? ??????? ? ??? ???????? ?????????. ??????????? ???? ????????? ????????? ????????? ????????????? ?????????????? ???????.

  8. Thermal analysis of a double layer phase change material floor

    International Nuclear Information System (INIS)

    Phase change materials (PCMs) can be used to shift the cooling or heating load from the peak period to the off-peak period. In this paper, a new double layer phase change material (PCM) floor is put forward. The two layers of PCM have different melting temperature. The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. According to the numerical model built in this paper, the thermal performances of the floor are analyzed. The results show that the optimal melting temperatures of PCMs exist. The fluctuations of the floor surface temperatures and the heat fluxes will be reduced and the system still can provide a certain amount of heat or cold energy after the heat pump or chiller has been turned off for a long time. Compared to the floor without PCM, the energy released by the floor with PCM in peak period will be increased by 41.1% and 37.9% during heating and cooling when the heat of fusion of PCM is 150 kJ/kg. - Highlights: ? A new double layer phase change material floor is put forward. ? The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. ? The optimal melting temperatures of PCMs in the system exist. ? The heat and cold energy released by the floor with PCM in peak period can be increased by 41.1% and 37.9%.

  9. Utilization of Industrial Waste Material in GSB Layer

    Directory of Open Access Journals (Sweden)

    U Arun Kumar

    2014-08-01

    Full Text Available India has series of steel plant clusters located along its length and breadth of the territory. Several million metric tons of iron and steel are produced in these plants annually. Along with the production of iron and steel, huge quantities of solid wastes like blast furnace slag and steel slag as well as other wastes such as flue dust, blast furnace sludge, and refractories are also being produced in these plants. These solid wastes can be used as non-traditional/non-conventional aggregates in pavement construction due to acute scarcity of traditional/conventional road construction materials. A study was conducted to investigate the possibility of using Granulated Blast Furnace Slag (GBFS with various blended mixes of traditional/conventional aggregates in subbase layer with different percentages. This study also presents the result of experimental investigation on the influence of Rice husk ash (RHA on the index properties of Red soil which is used as filler material in subbase layer.

  10. Sacrificial bonds and hidden length in biomaterials: A kinetic constitutive description of strength and toughness in bone

    Science.gov (United States)

    Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.

    2013-07-01

    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.

  11. 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.

  12. Bioactive gyroid scaffolds formed by sacrificial templating of nanocellulose and nanochitin hydrogels as instructive platforms for biomimetic tissue engineering.

    Science.gov (United States)

    Torres-Rendon, Jose Guillermo; Femmer, Tim; De Laporte, Laura; Tigges, Thomas; Rahimi, Khosrow; Gremse, Felix; Zafarnia, Sara; Lederle, Wiltrud; Ifuku, Shinsuke; Wessling, Matthias; Hardy, John G; Walther, Andreas

    2015-05-01

    A sacrificial templating process using lithographically printed minimal surface structures allows complex de novo geo-metries of delicate hydrogel materials. The hydrogel scaffolds based on cellulose and chitin nanofibrils show differences in terms of attachment of human mesenchymal stem cells, and allow their differentiation into osteogenic outcomes. The approach here serves as a first example toward designer hydrogel scaffolds viable for biomimetic tissue engineering. PMID:25833165

  13. Layered cathode materials for lithium ion rechargeable batteries

    Science.gov (United States)

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

    2007-04-17

    A number of materials with the composition Li.sub.1+xNi.sub..alpha.Mn.sub..beta.Co.sub..gamma.M'.sub..delta.O.sub.2-- zF.sub.z (M'=Mg,Zn,Al,Ga,B,Zr,Ti) for use with rechargeable batteries, wherein x is between about 0 and 0.3, .alpha. is between about 0.2 and 0.6, .beta. is between about 0.2 and 0.6, .gamma. is between about 0 and 0.3, .delta. is between about 0 and 0.15, and z is between about 0 and 0.2. Adding the above metal and fluorine dopants affects capacity, impedance, and stability of the layered oxide structure during electrochemical cycling.

  14. Calculation of electron and bremsstrahlung fields in heterogenous material layers

    International Nuclear Information System (INIS)

    The Ssub(N)-method, a numerical technique to solve the general transport equation is used to describe the passage of electrons through material layers and is discussed with respect to precision and difficulty in comparision with the Monte-Carlo-method. The production and tracking of secondary electrons and bremsstrahlung photons is taken into account. Therefore, the procedure allows investigations in a broad spectral region which is of interest for medical and technical applications. As results energy spectra and distributions in arrangements of different textures are reported for electron energies up to 20 MeV. With a reasonable need of computer time the influence of an inhomogeneous electron irradiation can be studied which is of great importance in electron radiation therapy. The integration of the necessary computer codes in the modular program system RSYST allows an almost automatic performance of calculation and data transfer. (orig./ORU)

  15. Particle-hole pair states of layered materials

    Science.gov (United States)

    Lokot, Lyubov E.

    2015-04-01

    In the paper a theoretical study of both the quantized energies of excitonic states and their wave functions in gapped graphene and in monolayer of MoS2 is presented. An integral two-dimensional Schrödinger equation of the electron-hole pairing for particles with electron-hole symmetry of reflection is analytically solved. The solutions of Schrödinger equation in momentum space in gapped graphene and in the direct band monolayer of MoS2 by projection the two-dimensional space of momentum on the three-dimensional sphere are found. We analytically solve an integral two-dimensional Schrödinger equation of the electron-hole pairing for particles with electron-hole symmetry of reflection and with strong spin-orbit coupling. In monolayer of MoS2 as well as in single-layer graphene (SLG) the electron-hole pairing leads to the exciton insulator states. Calculating an integral two-dimensional Schrödinger equation of the electron-hole pairing for bilayer graphene, exciton insulator states with a gap 3 meV are predicted. The particle-hole symmetry of Dirac equation of layered materials allows perfect pairing between electron Fermi sphere and hole Fermi sphere in the valence band and conduction band and hence driving the Cooper instability.

  16. Obtaining Hardened Layers of Heat-Resistant Steels by Plasma-Welding Deposition of Congeneric Materials

    Directory of Open Access Journals (Sweden)

    Yuri Dmitrievich Shitsyn

    2015-02-01

    Full Text Available The paper presents the research results on plasma-hardening of heat-resistant steel layers by plasma-welding deposition of congeneric materials under straight and reverse polarity current. The dependence of the deposited layer quality on the current polarity has been determined. A metallographic examination and measurement of micro-hardness of the deposited layer have been conducted. The dependence of the deposited layer characteristics on the welding parameters has been determined. The obtained results allow the use of plasma-welding deposition to obtain layers with the required strength characteristics using the material, congeneric to the parent material.

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

    CERN Document Server

    Vodolazhskaya, Larisa

    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. Related to the moon directions, as the most dedicated, identified. Revealed that the stone tools and fragments, used as sacrifices, mark the direction to the northern minor standstill moonrise. A similar situation was found on two archaeological sites: in Bezymennoye II settlement South sanctuary and in Pustynka settlement religious building. Drawing on ethnographic and folklore data, it is concluded about semiotic connection of stone tools, found in these religious constructions, with the "thunderstones" and meteorites.

  18. Sacrificial salts: Compensating the initial charge irreversibility in lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shanmukaraj, Devaraj; Grugeon, Sylvie; Laruelle, Stephane; Douglade, Gregory; Tarascon, Jean-Marie; Armand, Michel [Laboratoire de Reactivite et de Chimie des Solides, UMR CNRS 6007, Universite de Picardie Jules Verne, Amiens (France)

    2010-10-15

    Lithium salts enlisting azide, oxocarbons, dicarboxylates and hydrazides have been identified as a practical mean to compensate the irreversible capacity loss of LIBs negative electrodes. During the first charge, the anion loses electrons and converts to gaseous N{sub 2}, CO or CO{sub 2}, within an acceptable potential range (3 to 4.5 V). We report an electrochemical study on these easily accessible 'sacrificial salts'. (author)

  19. Photoreduction of graphene oxide enhanced by sacrificial agents.

    Science.gov (United States)

    Cho, Hsun-Wei; Wu, Jih-Jen

    2015-01-15

    In this work, the photoreduction of graphene oxides (GOs) was carried out in the presence of a sacrificial agent of Na2S/Na2SO3 and triethanolamine (TEA) separately in the solution. The photoreduction of GOs was enhanced with the addition of the sacrificial agent, which was examined in terms of reduction extent and needed reduction period. The quench of the GO emission was observed in the photoluminescence spectra of both GO solutions with Na2S/Na2SO3 and TEA. Although both sacrificial agents facilitated the charge transfer in the irradiated GO solutions, the aggregation of GO/reduced GO (RGO) occurred in the Na2S/Na2SO3-contained solution during photoreduction, which limited further photoreduction of GOs with the assistance of Na2S/Na2SO3. By keeping good dispersion characteristic during the whole process, the photoreduction efficiency of GO in the presence of TEA was therefore superior to that with the assistance of Na2S/Na2SO3. PMID:25454453

  20. Estimation of stresses in layers of dentures’ relining materials

    Directory of Open Access Journals (Sweden)

    J. ?mudzki

    2008-03-01

    Full Text Available Purpose: Durability tests of materials relining dentures should be carried out in conditions reflecting the realloading that accompanies bite force transmission. The influence of geometry resulting from a denture foundationshape on real stresses in relining has not been so far found.Design/methodology/approach: Using FEM modeling, identified were the stress levels in relining layers inconditions reflecting biting loading for two opposite cases of bone foundation atrophy.Findings: The equivalent Huber-Mises` stresses have not reached their critical values, although tangentialstresses on the interfacial where relining is bonded with denture base have reached 440kPa, which, for some of thecommercial types of relining denotes the bonding strength.Research limitations/implications: The linear elastic mechanical characteristics were assumed. Hence,during further research, taken into account should be the “stiffening” of characteristics in the upper loadings range,which is typical for silicones.Practical implications: In case of a convex foundation the biggest danger will be caused by any bond defectsoccurring in the central area because in that area shear of bond has reached the highest values.Originality/value: Values of stresses components identified in this paper reflect the real shear conditions ofrelining bonding with denture base and might constitute a determinant for strength tests.

  1. 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

  2. Method of forming aluminum oxynitride material and bodies formed by such methods

    Science.gov (United States)

    Bakas, Michael P. (Ammon, ID) [Ammon, ID; Lillo, Thomas M. (Idaho Falls, ID) [Idaho Falls, ID; Chu, Henry S. (Idaho Falls, ID) [Idaho Falls, ID

    2010-11-16

    Methods of forming aluminum oxynitride (AlON) materials include sintering green bodies comprising aluminum orthophosphate or another sacrificial material therein. Such green bodies may comprise aluminum, oxygen, and nitrogen in addition to the aluminum orthophosphate. For example, the green bodies may include a mixture of aluminum oxide, aluminum nitride, and aluminum orthophosphate or another sacrificial material. Additional methods of forming aluminum oxynitride (AlON) materials include sintering a green body including a sacrificial material therein, using the sacrificial material to form pores in the green body during sintering, and infiltrating the pores formed in the green body with a liquid infiltrant during sintering. Bodies are formed using such methods.

  3. Noise and vibration level reduction by covering metal structures with layers of damping materials. [considering viscoelastic insulation layers

    Science.gov (United States)

    Rugina, I.; Paven, H. T. O.

    1974-01-01

    One of the most important methods of reducing the noise and vibration level is the damping of the secondary sources, such as metal plates, often used in vehicle structures, by means of covering materials with high internal viscosity. Damping layers are chosen at an optimum thickness corresponding to the frequency and temperature range in which a certain structure works. The structure's response corresponding to various real situations is analyzed by means of a measuring chain including electroacoustical or electromechanical transducers. The experimental results provide the dependence of the loss factor and damping transmission coefficient as a function of the damping layer thickness or of the frequency for various viscoelastic covering materials.

  4. Method to measure thin deposited layers on a basic material

    International Nuclear Information System (INIS)

    A method for the non-destructive measurement of the layer thickness of deposits is described. Measurement is carried out by ?-irradiation of the deposits, recording of the backscattered radiation, and evaluation. (RW)

  5. 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 ...

  6. 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)

  7. Electrical Transport of Field-Effect Transistors Based on CVD Grown Two-Dimensional Layered Materials

    Science.gov (United States)

    Lin, Ming-Wei; Li, Xufan; Wang, Kai; Puretzky, Alexander; Rouleau, Christopher; Geohegan, David; Xiao, Kai; CNMS, ORNL Team

    2015-03-01

    By changing the layer numbers, the electrical transport of field effect transistors based on CVD grown two-dimensional (2D) layered materials of transition metal dichalcongenides (TMDCs) such as MoSe2, WSe2 and WS2 shown the different characteristics will be demonstrated. The transport measurements show that the altered semiconductor characteristics of these 2D materials can be possibly attributed to the shift of Fermi level when changing the number of layers. Besides, the transport characteristics can be tuned by adjusting the W/Mo doping level and mobility is also increased with increasing the layer numbers. In addition, the annealing effect on these CVD grown 2D layered materials will be discussed. This work is conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.

  8. Effect of outer layer thickness on full concentration gradient layered cathode material for lithium-ion batteries

    Science.gov (United States)

    Lee, Eung-Ju; Noh, Hyung-Joo; Yoon, Chong S.; Sun, Yang-Kook

    2015-01-01

    Full concentration gradient (FCG) layered cathode materials Li[Ni0.6-xCo0.15+xMn0.25]O2 (x = 0, 0.01, and 0.04) with different outer layer thicknesses are synthesized via a specially developed coprecipitation method. In the FCG cathode, the nickel concentration decreases linearly and the cobalt concentration increases from the center to particle surface throughout the particle at a fixed composition of Mn. The thickness of the FCG primary particle increases in the radial direction with an increasing outer layer thickness of the secondary particles and significantly affects the electrochemical performance. An increase in the stable outer layer thickness improves the cycle performance and thermal stability of the FCG materials at the expense of reversible capacity, whereas the rate capability and low temperature performance are significantly deteriorated by increasing outer layer thickness. All of the FCG materials exhibit superior electrochemical and thermal properties compared to the conventional cathode Li[Ni0.58Co0.17Mn0.25]O2 due to the unique microstructure of the FCG cathode.

  9. Light propagation in composite materials with gain layers

    Science.gov (United States)

    Dorofeenko, Aleksandr V.; Zyablovsky, A. A.; Pukhov, Aleksandr A.; Lisyansky, A. A.; Vinogradov, Aleksei P.

    2012-11-01

    Light propagation through a single gain layer and a multilayer system with gain layers is studied. Results obtained using the Fresnel formulas, Airy's series summation, and the numerical solution of the nonlinear Maxwell-Bloch equations by the finite difference time domain (FDTD) method are analyzed and compared. Normal and oblique propagation of a wave through a gain layer and a slab of a photonic crystal are examined. For the latter problem, the gain line may be situated in either the pass or stop band of the photonic crystal. It is shown that the monochromatic plane-wave approximation is generally inapplicable for active media, because it leads to results that violate causality. But the problem becomes physically meaningful and correct results can be obtained for all three approaches once the structure of the wavefront and the finite aperture of the beam are taken into account.

  10. "Determination of mechanical strength of different material double-layer rectangular tablets "

    Directory of Open Access Journals (Sweden)

    "Haririan I

    2000-08-01

    Full Text Available The mechanical strength of different material composite beams were assessed. All tablets were subjected to three-point bending test. For the preparation of tablets, the material of the lower layer was initially put in the die and compacted by a certain pressure. The second material was then put upon the first layer. Modulus of elasticity of the selected materials were used to interpret the behaviour of the top and bottom layers of the different materials composite tablets. Determination of the strength at the highest and lowest point of different material composite beams, showed that if the material with higher modulus of elasticity was placed at the lower layer, the value of compressive strength (?c obtained from exerting fracture load at the higher point, was more than the value obtained at the lower point (i.e. tensile strength, ?f. On the other hand, if the material of higher modulus of elasticity E, was located at the top surface, the stress value at the lower layer (?f was more than its value at the higher layer (i.e. ?c. The range of ?c/?f was 1/3, if number of components (n was much more than one. Inversely, when ‘n’ was less than 1, the value for ?c/?f was near 3.

  11. Mott p-n junctions in layered materials

    Science.gov (United States)

    Charlebois, Maxime; Hassan, Syed; Karan, Rajesh; Senechal, David; Tremblay, A.-M. S.

    2013-03-01

    Correlated electron heterostructure became a possible alternative when thin film deposition techniques achieved structures with a sharp interface transition. We study here the electronic reconstruction of doped Mott insulator p-n junctions based on a Cluster Dynamical Mean Field Theory (CDMFT) calculation of the Hubbard model in the limit where electrostatic energy dominates over the kinetic energy associated with transport across layers. The grand potential of individual layers is first computed within CDMFT and then the electrostatic potential energy is taken into account in the Hartree approximation. The charge reconstruction in an ensemble of stacked planes of different nature can lead to a distribution of electron charge, density of states, and optical properties that are unique to doped-Mott insulators. Correlated electron heterostructure became a possible alternative when thin film deposition techniques achieved structures with a sharp interface transition. We study here the electronic reconstruction of doped Mott insulator p-n junctions based on a Cluster Dynamical Mean Field Theory (CDMFT) calculation of the Hubbard model in the limit where electrostatic energy dominates over the kinetic energy associated with transport across layers. The grand potential of individual layers is first computed within CDMFT and then the electrostatic potential energy is taken into account in the Hartree approximation. The charge reconstruction in an ensemble of stacked planes of different nature can lead to a distribution of electron charge, density of states, and optical properties that are unique to doped-Mott insulators. This work was supported by NSERC, CIFAR and CRC

  12. 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)

  13. Elastic measurements of layered nanocomposite materials by Brillouin spectroscopy

    OpenAIRE

    Lefeuvre, O.; Kolosov, Ov; Every, Ag; Briggs, Ga; Tsukahara, Y.

    2000-01-01

    Surface Brillouin spectroscopy makes it possible to measure surface elastic wave propagation parameters at frequencies up to 20 GHz or more. This enables us to measure the elastic properties of surface layers only a small fraction of a micrometre thick. The wavelength and incident angle of the light determine the wavenumber of surface elastic waves (SAW) that scatter the light inelastically, and their frequency can be found by measuring the change in wavelength of the scattered light. By anal...

  14. Self-organized electronic superlattices in layered materials

    OpenAIRE

    Ortix, Carmine; Di Castro, Carlo; Lorenzana, José

    2014-01-01

    We show that in layered systems with electronic phase separation tendency, the long-range Coulomb interaction can drive the spontaneous formation of unidirectional superlattices of electronic charge in a completely homogeneous crystalline background. In this self-organized electronic heterostructure, the ratio among the number of crystalline planes in the minority and majority electronic phases corresponds to Farey fractions with the superlattice period controlled by the bac...

  15. Teo-iconología del poder sacrificial entre los mochica Teo-iconology of sacrificial power among the Moche

    Directory of Open Access Journals (Sweden)

    Adolfo Chaparro Amaya

    2011-12-01

    Full Text Available Partiendo de las evidencias icónicas del rasgo predatorio y sus equivalentes narrativos presentes en diferentes piezas de la cultura mochica, el texto busca establecer (i una metodología de aproximación al sacrificio caníbal que tenga en cuenta diversas formas icónicas de ‹escritura›, y (ii una explicación so-ciocósmica de la política sacrificial. Al articular lo escritural y lo político, es posible aportar una nueva perspectiva a la rica discusión que sobre las relaciones entre canibalismo y poder han venido proponiendo los arqueólogos, los semióticos y los antropólogos de las culturas prehispánicas.Based on the iconographic evidences of predation and their narrative equivalents, present in different aspects of the Mochica culture, this essay seeks to establish (i a methodology for approaching the cannibal sacrifice taking into account different forms of iconic ‹writing›; and (ii establish a socio-cosmic explanation to sacrificial politics. By articulating these scriptural and political aspects, the paper will provide a new perspective to the rich discussion on the relationship between cannibalism and power that has been proposed by archaeologists, anthropologists and studies on the semiotic of Prehispanic cultures.

  16. Teo-iconología del poder sacrificial entre los mochica / Teo-iconology of sacrificial power among the Moche

    Scientific Electronic Library Online (English)

    Adolfo, Chaparro Amaya.

    2011-12-01

    Full Text Available Partiendo de las evidencias icónicas del rasgo predatorio y sus equivalentes narrativos presentes en diferentes piezas de la cultura mochica, el texto busca establecer (i) una metodología de aproximación al sacrificio caníbal que tenga en cuenta diversas formas icónicas de ‹escritura›, y (ii) una ex [...] plicación so-ciocósmica de la política sacrificial. Al articular lo escritural y lo político, es posible aportar una nueva perspectiva a la rica discusión que sobre las relaciones entre canibalismo y poder han venido proponiendo los arqueólogos, los semióticos y los antropólogos de las culturas prehispánicas. Abstract in english Based on the iconographic evidences of predation and their narrative equivalents, present in different aspects of the Mochica culture, this essay seeks to establish (i) a methodology for approaching the cannibal sacrifice taking into account different forms of iconic ‹writing›; and (ii) establish a [...] socio-cosmic explanation to sacrificial politics. By articulating these scriptural and political aspects, the paper will provide a new perspective to the rich discussion on the relationship between cannibalism and power that has been proposed by archaeologists, anthropologists and studies on the semiotic of Prehispanic cultures.

  17. 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

  18. Computational synthesis of single-layer GaN on refractory materials

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Arunima K.; Hennig, Richard G., E-mail: rhennig@cornell.edu [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States)

    2014-08-04

    The synthesis of single-layer materials relies on suitable substrates. In this paper, we identify suitable substrates for the stabilization and growth of single-layer GaN and characterize the effect of the substrate on the electronic structure of single-layer GaN. We identify two classes of epitaxial substrates, refractory metal diborides and transition-metal dichalcogenides. We find that the refractory diborides provide epitaxial stabilization for the growth and functionalization of single layer GaN. We show that chemical interactions of single layer GaN with the diboride substrates result in n-type doping of the single-layer GaN. Transition-metal dichalcogenides, on the other hand, although epitaxially matched, cannot provide sufficient thermodynamic stabilization for the growth of single layer GaN. Nonetheless, energy band alignments of GaN/metal chalcogenides show that they make good candidates for heterostructures.

  19. 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.

  20. 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.

  1. Fabrication of membranes and microchannels in low-temperature co-fired ceramic (LTCC) substrate using novel water-based sacrificial carbon pastes

    OpenAIRE

    Malecha, Karol; Maeder, Thomas; Jacq, Caroline

    2012-01-01

    In this work, 3D structuration of LTCC (low-temperature co-fired ceramic) for microfluidics was studied, using two novel sacrificial carbon paste compositions. These pastes are based on graphite with a water-soluble vehicle consisting of polyvinylpyrrolidone binder (PVP) dissolved in propylene glycol (PG), which is not aggressive to green LTCC material. Both examined pastes differ slightly in binder content and added plasticizer, glycerol (G) or trimethylolpropane (TMP). The thermal propertie...

  2. A estrutura sacrificial do compadrio: uma ontologia da desigualdade?

    Directory of Open Access Journals (Sweden)

    Marcos Lanna

    2009-01-01

    It is shown that god-parenthood is not only a religious or kinship institution and that it does not reinforce inequalities that supposedly pre-exist it, but rather it is a structure that generates inequalities. God-parenthood is understood as a structure by the description of reciprocity circuits. Understood as the circulation of a child from biological towards spiritual parents, to be returned by "grace", it implies asymmetries and inequalities. It also evokes the ontology of the social, founded on non-mercantile values' circulation, and on what Sahlins (2008 designates "elementary structure of political life". It is shown that reciprocity is related to the sacrificial aspect of the child's gift, and also to other types of considerations, such as that present in the catholic vows. Finally, it is demonstrated the relevancy of this type of analysis for future understandings of other benefits and categories often taken as purely economic ones, such as "labor".

  3. 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

  4. Performance of Al-Zn-Sn alloy sacrificial anode in seawater

    International Nuclear Information System (INIS)

    The paper describes the performance of Al-Zn-Sn alloy as a sacrificial anode for cathodic protection in seawater was investigated. Electrochemical technique used for measuring corrosion rate of the Al-Zn-Sn alloy sacrificial anode were Tafel plot. Potential measurement was also carried out using lab apparatus. All aspects of measurements such as corrosion potential, samples dimension and samples composition are presented in details. Experimental data and analysis results will be used in evaluating the performance of Al-Zn-Sn alloy sacrificial anode in seawater and will be discussed in this paper. (Author)

  5. Fully three-dimensional microfabrication with a grayscale polymeric self-sacrificial structure

    International Nuclear Information System (INIS)

    We present in this paper a novel method to fabricate fully three-dimensional (3D) microstructures and moving parts using a partially crosslinked polymer as sacrificial supports. This is realized on a projection microstereolithography (PµSL) which produces both the microstructure and the sacrificial part simultaneously using digital grayscale images. To establish the selectivity of the etchant to the partially crosslinked sacrificial parts, we measured the etching rate as a function of photo-crosslinking light intensity and the light exposure time. This technology may enable more complex scaffolds in tissue engineering and smart hydrogel devices

  6. Experimental studies on the performance of novel layered materials under highly dynamic loads

    International Nuclear Information System (INIS)

    This paper focuses on the experimental observations of the performance of different layered composite material systems subjected to blast loadings. These material systems include layered composites and sandwich composite materials. A controlled blast loading of pre-defined pressure magnitude and rise time were obtained using a shock tube apparatus. Rectangular plate elements of the desired material system were subjected to such a controlled blast loading and the effects of the blast loading on these elements were studied using optical and residual strength measurements. A high speed imaging technique was utilized to study the damage modes and mechanisms in real time. It was observed that layering of a conventional composite material with a soft visco-elastic polymer provided better blast resistance and sandwiching the polymer greatly enhanced its survivability under extreme air blast conditions. Aside from layering the conventional composite material with a soft visco-elastic polymer, it was observed that layering or grading the core can successfully mitigate the impact damage and thus improve the overall blast resistance as well. In addition to these, three dimensional (3D) woven skin and core reinforcements were introduced in the conventional sandwich composites and their effects on the blast resistance were studied experimentally. It was observed that these reinforcements also enhance the blast resistance of conventional sandwich composites by changing the mechanisndwich composites by changing the mechanism of failure initiation and propagation in these sandwich structures.

  7. Metalorganic chemical vapor deposition of gallium nitride on sacrificial substrates

    Science.gov (United States)

    Fenwick, William Edward

    GaN-based light emitting diodes (LEDs) face several challenges if the technology is to continue to make a significant impact in general illumination, and on technology that has become known as solid state lighting (SSL). Two of the most pressing challenges for the continued penetration of SSL into traditional lighting applications are efficacy and total lumens from the device, and their related cost. The development of alternative substrate technologies is a promising avenue toward addressing both of these challenges, as both GaN-based device technology and the associated metalorganic chemical vapor deposition (MOCVD) technology are already relatively mature technologies with a well-understood cost base. Zinc oxide (ZnO) and silicon (Si) are among the most promising alternative substrates for GaN epitaxy. These substrates offer the ability to access both higher efficacy and lumen devices (ZnO) at a much reduced cost. This work focuses on the development of MOCVD growth processes to yield high quality GaN-based materials and devices on both ZnO and Si. ZnO is a promising substrate for growth of low defect-density GaN because of its similar lattice constant and thermal expansion coefficient. The major hurdles for GaN growth on ZnO are the instability of the substrate in a hydrogen atmosphere, which is typical of nitride growth conditions, and the inter-diffusion of zinc and oxygen from the substrate into the GaN-based epitaxial layer. A process was developed for the MOCVD growth of GaN and InxGa 1-xN on ZnO that attempted to address these issues. The structural and optical properties of these films were studied using various techniques. X-ray diffraction (XRD) showed the growth of wurtzite GaN on ZnO, and room-temperature photoluminescence (RT-PL) showed near band-edge luminescence from the GaN and InxGa1-xN layers. However, high zinc and oxygen concentrations due to interdiffusion near the ZnO substrate remained an issue; therefore, the diffusion of zinc and oxygen into the subsequent GaN layer was studied in more detail. Several approaches were investigated---for example, transition layers such as Al2O3 and Al xGa1-xN/GaN---to minimize diffusion of these impurities into the GaN layer. Silicon, due to its prevalence, is the most promising material for the development of an inexpensive, large-area substrate technology. The challenge in MOCVD growth of GaN on Si is the tensile strain induced by the lattice and thermal mismatch between GaN and Si and the formation of anti-phase boundaries. Typical approaches to solve these problems involve complicated and multiple buffer layer structures, which lead to relatively slow growth rates. In this work, a thin atomic layer deposition (ALD)-grown Al2O3 interlayer was employed to relieve strain and increase material quality while also simplifying the growth process. While some residual strain was still observed in the GaN material by XRD and PL, the use of this oxide interlayer leads to an improvement in thin film quality as seen by a reduction in both crack density (% as measured by LT-PL, compared to ˜37% on sapphire, but this difference can be assigned to the difference in indium compositions. These results show a great promise toward an inexpensive, large-area, silicon-based substrate technology for MOCVD growth of the next generation of GaN-based optoelectronic devices for SSL and other applications.

  8. The Influnece of Peat Layer on Hidrogen and Aluminium Concentration Originating from the Substratum Sulphidic Materials

    OpenAIRE

    Benito Heru Purwanto; Eko Hanudin; Bostang Radjagukguk; Arifin Fahmi

    2012-01-01

    Much of peatland in Indonesia has sulphidic materials as substratum. Soil acidity and metal elements in peatland may originate from the sulphidic materials which occur underneath of the peat layer. Peat soil buffering capacity and chelating ability of the peat materials regulate the soil acidity and metal solubility in the peatland. The study was aimed to examine the influence of peat thickness and land hydrological conditions on the concentrations of exchangeable aluminium (Al) and hidrogen ...

  9. Improving impact resistance of ceramic materials by energy absorbing surface layers

    Science.gov (United States)

    Kirchner, H. P.; Seretsky, J.

    1974-01-01

    Energy absorbing surface layers were used to improve the impact resistance of silicon nitride and silicon carbide ceramics. Low elastic modulus materials were used. In some cases, the low elastic modulus was achieved using materials that form localized microcracks as a result of thermal expansion anisotropy, thermal expansion differences between phases, or phase transformations. In other cases, semi-vitreous or vitreous materials were used. Substantial improvements in impact resistance were observed at room and elevated temperatures.

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

    International Nuclear Information System (INIS)

    The influence of indium tin oxide [(In2O3: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 (?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:PC61BM and PCPDTBT:PC71BM active layers. The optimal values of n, t and ?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.

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

    Science.gov (United States)

    Doggart, P.; Bristow, N.; Kettle, J.

    2014-09-01

    The influence of indium tin oxide [(In2O3: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 (?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:PC61BM and PCPDTBT:PC71BM active layers. The optimal values of n, t and ?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.

  12. 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.

  13. Behavior of alumina barrier layer in the supporting electrolytes for deposition of nanowired materials

    International Nuclear Information System (INIS)

    In this study, we report the results obtained investigating the behavior of sulfuric and chromic acid alumina templates in typical supporting electrolytes frequently used for alternating current (ac) deposition of various nm-scaled materials. Qualitative analysis of voltammetric profiles taken for as-grown, ac-treated and annealed alumina films in a conventional tetraborate re-anodizing solution revealed dramatical changes in the properties of alumina barrier layer during ac treatment in these supporting electrolytes even at low current density. These changes were related here with the transport of protons through the barrier layer during ac treatment, discharge at the metal/oxide interface and hydrogenation of alumina material by hydrogen atoms in an upward way. This conclusion comes from the behavior of Pt/Hg|alumina|Mez+ electrode and the valence band X-ray photoelectron spectra taken from the inner part of alumina barrier layer material before and after the ac treatment.

  14. Investigation of Materials for Boundary Layer Control in a Supersonic Wind Tunnel

    Science.gov (United States)

    Braafladt, Alexander; Lucero, John M.; Hirt, Stefanie M.

    2013-01-01

    During operation of the NASA Glenn Research Center 15- by 15-Centimeter Supersonic Wind Tunnel (SWT), a significant, undesirable corner flow separation is created by the three-dimensional interaction of the wall and floor boundary layers in the tunnel corners following an oblique-shock/ boundary-layer interaction. A method to minimize this effect was conceived by connecting the wall and floor boundary layers with a radius of curvature in the corners. The results and observations of a trade study to determine the effectiveness of candidate materials for creating the radius of curvature in the SWT are presented. The experiments in the study focus on the formation of corner fillets of four different radii of curvature, 6.35 mm (0.25 in.), 9.525 mm (0.375 in.), 12.7 mm (0.5 in.), and 15.875 mm (0.625 in.), based on the observed boundary layer thickness of 11.43 mm (0.45 in.). Tests were performed on ten candidate materials to determine shrinkage, surface roughness, cure time, ease of application and removal, adhesion, eccentricity, formability, and repeatability. Of the ten materials, the four materials which exhibited characteristics most promising for effective use were the heavy body and regular type dental impression materials, the basic sculpting epoxy, and the polyurethane sealant. Of these, the particular material which was most effective, the heavy body dental impression material, was tested in the SWT in Mach 2 flow, and was observed to satisfy all requirements for use in creating the corner fillets in the upcoming experiments on shock-wave/boundary-layer interaction.

  15. 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

  16. 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.

  17. Nanolithography in thermally sacrificial polymers using nanoscale thermal probes

    Science.gov (United States)

    Hua, Yueming; Saxena, Shubham; King, William P.; Henderson, Clifford L.

    2006-03-01

    This paper reports a novel lithography method that utilizes local nanoscale thermal decomposition of polycarbonate films using heated atomic force microscope cantilever probe tips. The effect of polycarbonate structure and physiochemical properties on the lithographic performance of the thermal writing process have been explored. It is observed that amorphous linear polycarbonates which possess glass transition temperatures lower than their decomposition temperature generally exhibit substantial thermal deformation during thermal writing. In contrast, thermal writing on crystalline regions of semi-crystalline linear polycarbonate films produced good pattern definition. However, the semi-crystalline nature of the film results in substantial surface topography in the thin film which is undesirable for high resolution patterning and the amorphous regions of the film still suffer from local thermal deformation during writing. Amorphous cross-linkable polycarbonate sacrificial polymers have been synthesized and are shown to be able to resist thermal deformation of features during writing and are shown capable of producing good patterned images using the heated AFM probe writing technique.

  18. 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

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

    Science.gov (United States)

    Krumhansl, James L; Nenoff, Tina M

    2013-02-26

    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.

  20. 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

  1. Formation of a screening layer under irradiation of solid materials by power plasma flows

    International Nuclear Information System (INIS)

    The dynamics of the target plasma, formed by irradiation of solid-state materials by high-temperature currents of hydrogen plasma with the power density of W ? 10 MW/cm2, is experimentally studied. Interaction of the plasma with the materials proceeded in the magnetic field, oriented perpendicular to the surface. Graphite, plexiglas, quartz, boron nitride, aluminium, stainless steel, copper, molybdenum, tungsten were used as the target material. It is shown that a dense layer (n > 1017 cm-3) of the target plasma, screening the surface from the direct impact of the plasma current, is formed during t = 1-2 ?s on the irradiated surface. The magnetic field limits the target plasma expansion across the power lines and establishes unidimensional hydrodynamical behavior of the plasma. The dynamics and parameters of the screening layer plasma essentially depend on the target materials

  2. 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.

  3. 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.

  4. 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 ...

  5. 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...

  6. 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.

  7. Approximate Electromagnetic Cloaking of a Dielectric Sphere Using Homogeneous Isotropic Multi-Layered Materials

    Directory of Open Access Journals (Sweden)

    Hany M. Zamel

    2013-10-01

    Full Text Available In cloaking, a body is hidden from detection by surrounding it by a coating consisting of an unusual anisotropic nonhomogeneous material. The permittivity and permeability of such a cloak are determined by the coordinate transformation of compressing a hidden body into a point or a line. The radially-dependent spherical cloaking shell can be approximately discretized into many homogeneous anisotropic layers; each anisotropic layer can be replaced by a pair of equivalent isotropic sub-layers, where the effective medium approximation is used to find the parameters of these two equivalent sub-layers. In this work, the scattering properties of cloaked dielectric sphere is investigated using a combination of approximate cloaking, where the dielectric sphere is transformed into a small sphere rather than to a point, together with discretizing the cloaking material using pairs of homogeneous isotropic sub-layers. The back-scattering normalized radar cross section, the scattering patterns are studied and the total scattering cross section against the frequency for different number of layers and transformed radius.

  8. Polymer/graphite oxide composites as high-performance materials for electric double layer capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Tien, Chien-Pin; Teng, Hsisheng [Department of Chemical Engineering and Center for Micro/Nano Science and Technology, National Cheng Kung University, No. 1 Ta-Hsueh Road, Tainan 70101 (China)

    2010-04-15

    A single graphene sheet represents a carbon material with the highest surface area available to accommodating molecules or ions for physical and chemical interactions. Here we demonstrate in an electric double layer capacitor the outstanding performance of graphite oxide for providing a platform for double layer formation. Graphite oxide is generally the intermediate compound for obtaining separated graphene sheets. Instead of reduction with hydrazine, we incorporate graphite oxide with a poly(ethylene oxide)-based polymer and anchor the graphene oxide sheets with poly(propylene oxide) diamines. This polymer/graphite oxide composite shows in a ''dry'' gel-electrolyte system a double layer capacitance as high as 130 F g{sup -1}. The polymer incorporation developed here can significantly diversify the application of graphene-based materials in energy storage devices. (author)

  9. Investigations of the effects of siderite weighted material on the reservoir properties of producing layers

    Energy Technology Data Exchange (ETDEWEB)

    Krezub, A.P.; Rylov, N.I.

    1981-01-01

    The effect of the drilling solution's solid and fluid phases on changes in permeability in core samples is discussed. Advantages of using siderite weighted material are discussed, which thanks to an almost complete dissolution in hydrochloric acid reestablishes the natural permeability of layers.

  10. Test of the material for radon seal layer at the mine waste disposal site Jazbec

    International Nuclear Information System (INIS)

    About 1.4 million t of mine waste was deposited at the mine waste disposal site Jazbec during the mining of ore at the Zirovski vrh uranium mine. The average concentration of uranium in the mine waste is about 60 g/t, the average specific activity of 226Ra is 730 Bq/m3. To reduce the radon exhalation rate and the penetration of rainfall water into the waste pile, it should be covered with an appropriate material. The surface of the waste pile is about 5 ha. The thickness of the cover should be about 2 m. A test field on the waste pile Jazbec (100 m long and 12-20 m wide) was constructed in 2003. The surface of the test field was separated into two parts: one part with a multi-layer cover (5 layers), the second part with only two layers. For the seal layer, fine clayey silt and sand were used. Measurements of radon exhalation were carried out on the mine waste material, on the seal layer, on the protection layer and finally on the humus layer. For the radon exhalation measurements, the method with charcoal absorbers was applied. The time of exposure was 48 h. The results of the radon exhalation rates confirmed that clayey silt and sand mixture is an adequate material to use as a radon barrier. The average results of the radon exhalation rates were 50% and more lower than the prescribed authorized limit of 0.1 Bq·m2s-1. The results of the water penetration measurements were not as low as is required by the regulations. The imas is required by the regulations. The improvement of clayey silt and sand characteristics with bentonite was also evaluated. (author)

  11. 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

    2015-01-01

    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

  12. First principles characterization of novel single-layer materials predicted with an evolutionary algorithm

    Science.gov (United States)

    Revard, Benjamin; Tipton, Will; Hennig, Richard

    2015-03-01

    Single-layer materials represent a new materials class with potentially transformative properties for applications in nanoelectronics and solar-energy harvesting. With the goal to discover novel 2D materials with unexpected compositions and structures, we have developed a grand-canonical evolutionary algorithm for two-dimensional materials. Here we present the results of applying the algorithm, coupled with first principles total energy methods, to several technologically relevant binary 2D systems, including C-Si, Sn-S and PbO. We currently use computational techniques to characterize the vibrational and electronic properties of the low energy 2D materials predicted by the algorithm and will report the findings. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144153.

  13. Modifying the interlayer interaction in layered materials with an intense IR laser.

    Science.gov (United States)

    Miyamoto, Yoshiyuki; Zhang, Hong; Miyazaki, Takehide; Rubio, Angel

    2015-03-20

    We propose a transient interlayer compression in two-dimensional compound materials by using an intense IR laser resonant with the out-of-plane optical phonon mode (A(2u) mode). As a test case, we studied bilayer hexagonal boron nitride (h-BN), which is one of the compound layered materials. Excited state molecular dynamics calculations using time-dependent density functional theory show an 11.3% transient interlayer contraction of h-BN due to an interlayer dipole-dipole attraction of the laser-pumped A(2u) mode. These results are applicable to other layered compound materials. Such layered materials are a good material for nanospace chemistry, e.g., intercalating molecules and acting with them, and IR irradiation to contract the interlayer distance could provide a new route for chemical reactions under pressure. The duration of the contraction is at least 1 ps in the current simulation, which is observable by high-speed electron-beam diffraction measurements. PMID:25839294

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

    Energy Technology Data Exchange (ETDEWEB)

    Hirvikorpi, Terhi, E-mail: terhi.hirvikorpi@vtt.f [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Vaehae-Nissi, Mika, E-mail: mika.vaha-nissi@vtt.f [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Harlin, Ali, E-mail: ali.harlin@vtt.f [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Karppinen, Maarit, E-mail: maarit.karppinen@tkk.f [Laboratory of Inorganic Chemistry, Department of Chemistry, Aalto University School of Science and Technology, Kemistintie 1, P.O. Box 16100, FI-00076 AALTO (Finland)

    2010-07-30

    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.

  15. 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.

  16. Effect of base layer materials on physiological and perceptual responses to exercise in personal protective equipment.

    Science.gov (United States)

    Smith, Denise L; Arena, Logan; DeBlois, Jacob P; Haller, Jeannie M; Hultquist, Eric M; Lefferts, Wesley K; Russell, Tim; Wu, Annie; Fehling, Patricia C

    2014-05-01

    Ten men (non-firefighters) completed a 110 min walking/recovery protocol (three 20-min exercise bouts, with recovery periods of 10, 20, and 20 min following successive bouts) in a thermoneutral laboratory while wearing firefighting personal protective equipment over one of four base layers: cotton, modacrylic, wool, and phase change material. There were no significant differences in changes in heart rate, core temperature, rating of perceived exertion, thermal discomfort, and thermal strain among base layers. Sticking to skin, coolness/hotness, and clothing humidity sensation were more favorable (p heat dissipation did not correspond with physiological responses during exercise or recovery. PMID:23849898

  17. 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.

  18. Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

    2004-01-01

    Full Text Available The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ultra-low carbon interstitial free steel, austenitic stainless steel (SUS304, 99.99 wt.%Al, commercial purity aluminum (A1050 and A1100, Al–Mg alloy (A5083, Al-4 wt.%Cu alloy, OFHC-Cu (C1020, Cu–Zn alloy (C2600 and Pb-1.5%Sn alloy. In case of the 1050-H24 aluminum, the depth of the surface nanocrystalline layer was about 15 ?m. It was clarified that wire-brushing is an effective way of NS-SPD, and surface nanocrystallization can be easily achieved in most of metallic materials.

  19. The Influnece of Peat Layer on Hidrogen and Aluminium Concentration Originating from the Substratum Sulphidic Materials

    Directory of Open Access Journals (Sweden)

    Benito Heru Purwanto

    2012-09-01

    Full Text Available Much of peatland in Indonesia has sulphidic materials as substratum. Soil acidity and metal elements in peatland may originate from the sulphidic materials which occur underneath of the peat layer. Peat soil buffering capacity and chelating ability of the peat materials regulate the soil acidity and metal solubility in the peatland. The study was aimed to examine the influence of peat thickness and land hydrological conditions on the concentrations of exchangeable aluminium (Al and hidrogen (H in the peatland. The study was carried out on peaty acid sulphate soil, deep peat, moderate peat and shallow peat. Exchangeable Al and H were observed in the wet season, transition from wet to dry season and dry season. The results showed that exchangeables of Al and H were mainly originated from sulphidic material which were occured underneath of the peat layer. Peat layer had an important role on the solubility of Al and H in the peatland. Peat thickness had influence on exchangeable-Al and H, 50 cm of the peat thickness (shallow peat was the critical for peat function to reduce the Al and H solubility in the peatland. Hydrological condition factor did not influence on the solubility of Al and H.

  20. Microstructural characterization of mixed-material deposition layer on the LHD divertor tiles by using nano-geological diagnosis

    Science.gov (United States)

    Tokitani, M.; Masuzaki, S.; Yoshida, N.; Sagara, A.; Noda, N.; Yamada, H.; LHD Experiment Group

    2013-07-01

    Fusion plasma research crucially needs to understand the characteristics of the deposition layer that forms in the vacuum vessel because of the migration of plasma-facing materials. Such a deposition layer can accumulate on the fuel particles on account of a co-deposition process and can be a source of dust in the plasma. In this study, nano-geological diagnosis which uses a focused ion beam (FIB) fabrication technique and transmission electron microscope (TEM) observations, has been applied to the mixed-material deposition layer formed in a large helical device (LHD). A cross-sectional view of the deposition layer with nanometer resolution was successfully observed. The total thickness of the layer was estimated at ˜8 ?m, and it has very fine and stratified layer structures in the nanometer level. The characteristics of each layer are indicative of the operational history of the LHD and the mechanism of dust formation by layer flaking.

  1. Microstructural characterization of mixed-material deposition layer on the LHD divertor tiles by using nano-geological diagnosis

    International Nuclear Information System (INIS)

    Fusion plasma research crucially needs to understand the characteristics of the deposition layer that forms in the vacuum vessel because of the migration of plasma-facing materials. Such a deposition layer can accumulate on the fuel particles on account of a co-deposition process and can be a source of dust in the plasma. In this study, nano-geological diagnosis which uses a focused ion beam (FIB) fabrication technique and transmission electron microscope (TEM) observations, has been applied to the mixed-material deposition layer formed in a large helical device (LHD). A cross-sectional view of the deposition layer with nanometer resolution was successfully observed. The total thickness of the layer was estimated at ?8 ?m, and it has very fine and stratified layer structures in the nanometer level. The characteristics of each layer are indicative of the operational history of the LHD and the mechanism of dust formation by layer flaking

  2. On unusual narrow transmission bands for a multi-layered periodic structure containing left-handed materials

    OpenAIRE

    Wu, Liang; He, Sailing; Chen, Long

    2002-01-01

    A multi-layered structure consisting of alternate right-handed material (RHM) and left-handed material (LHM)is considered and the unusual narrow transmission bands are explained as the competitive results of the Bragg condition and the transparent condition. These unusual narrow transmission bands may exist regardless whether the optical length of the LHM layer cancels the optical length of the RHM layer or not. This unusual transmission property may disappear when the refle...

  3. Layered tungsten oxide-based organic/inorganic hybrid materials I: Infrared and Raman study

    CERN Document Server

    Ingham, B

    2004-01-01

    Tungsten oxide-organic layered hybrid materials have been studied by infrared and Raman spectroscopy, and demonstrate a difference in bonding nature as the length of the interlayer organic `spacer' molecule is increased. Ethylenediamine-tungsten oxide clearly displays a lack of terminal -NH3^+ ammonium groups which appear in hybrids with longer alkane molecules, thus indicating that the longer chains are bound by electrostatic interactions as well as or in place of the hydrogen bonding that must be present in the shorter chain ethylenediamine hybrids. The presence of organic molecules between the tungsten oxide layers, compared with the layered tungstic acid H2WO4, shows a decrease in the apical W=O bond strength, as might be expected from the aforementioned electrostatic interaction.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Anomalous elastic buckling of hexagonal layered crystalline materials in the absence of structure slenderness

    OpenAIRE

    Ren, Manrui; Liu, Jeffernson Zhe; Wang, Lifeng; Zheng, QuanShui

    2014-01-01

    Hexagonal layered crystalline materials, such as graphene, boron nitride, tungsten sulfate, and so on, have attracted enormous attentions, due to their unique combination of atomistic structures and superior thermal, mechanical, and physical properties. Making use of mechanical buckling is a promising route to control their structural morphology and thus tune their physical properties, giving rise to many novel applications. In this paper, we employ finite element analysis (...

  9. Layered tungsten oxide-based organic/inorganic hybrid materials I: Infrared and Raman study

    OpenAIRE

    Ingham, B.; Chong, S V; Tallon, J. L.

    2004-01-01

    Tungsten oxide-organic layered hybrid materials have been studied by infrared and Raman spectroscopy, and demonstrate a difference in bonding nature as the length of the interlayer organic `spacer' molecule is increased. Ethylenediamine-tungsten oxide clearly displays a lack of terminal -NH3+ ammonium groups which appear in hybrids with longer alkane molecules, thus indicating that the longer chains are bound by electrostatic interactions as well as or in place of the hydrog...

  10. Thermo-electric performance investigation of two layer inhomogeneous doped graded material FeSi2

    International Nuclear Information System (INIS)

    The two layer inhomogeneous graded ? phase FeSi2 was preparated by Field-activated method. The dopant content in the interface was analyzed by WDS. The Seebeck coefficient and resistivity of Mn-doped and Co-doped inhomogeneous doped samples were measured. Power factor of samples were calculated. Compared with homogeneous materials, this kind of inhomogeneous dopant structure can adjust the relation between the thermo-electric performance and temperature

  11. Employing Adaptive Finite Elements to Model Squeezing of a Layered Material in 3D

    Directory of Open Access Journals (Sweden)

    Marcin Sieniek

    2013-11-01

    Full Text Available In this paper we employ 3D hp-adaptive finite element method (hp-FEM to model the behavior of a squeezed layered material. Under a moderate pressure, the linear elasticity model can be used to imitate the process. Thanks to hp-adaptivity, only the regions where the error rate is high are refined, making sure that all peculiarities are automatically localized

  12. 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.

  13. 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

  14. Guided Modes in a Four-Layer Slab Waveguide with Dispersive Left-Handed Material

    Directory of Open Access Journals (Sweden)

    Lufa Shen

    2010-05-01

    Full Text Available A four-layer slab waveguide including left-handed material is investigated numerically in this paper. Considering left-handed material dispersion, we find eight TE guided modes as frequency from 4 GHz to 6 GHz. The fundamental mode can exist, and its dispersion curves are insensitive to the waveguide thickness. Besides, the total power fluxes of TE guided modes are analyzed and corresponding new properties are found, such as: positive and negative total power fluxes coexist; at maximum value of frequency, we find zero total power flux, etc. Our results may be of benefit to the optical waveguide technology.

  15. 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.

  16. Preparation of thin layer materials with macroporous microstructure for SOFC applications

    Science.gov (United States)

    Marrero-López, D.; Ruiz-Morales, J. C.; Peña-Martínez, J.; Canales-Vázquez, J.; Núñez, P.

    2008-04-01

    A facile and versatile method using polymethyl methacrylate (PMMA) microspheres as pore formers has been developed to prepare thin layer oxide materials with controlled macroporous microstructure. Several mixed oxides with fluorite and perovskite-type structures, i.e. doped zirconia, ceria, ferrites, manganites, and NiO-YSZ composites have been prepared and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and mercury porosimetry. The synthesised materials are nanocrystalline and present a homogeneous pore distribution and relatively high specific surface area, which makes them interesting for SOFC and catalysis applications in the intermediate temperature range.

  17. 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)

  18. Structural factors affecting lithium transport in lithium-excess layered cathode materials

    Science.gov (United States)

    Fell, Christopher R.

    Lithium ion batteries have drawn significant attention as the principle energy storage device powering today's mobile electronic equipment. Despite the increased usage, the performance of current lithium ion battery technology falls short of the requirements needed for large format applications such as electric vehicles. The layered lithium-excess oxide compounds Li[NixLi1/3-2x/3Mn2/3-x/3]O2 are of interest as a new generation of cathode materials for high energy density lithium ion batteries. Efforts to achieve a better understanding of the electrochemistry of lithium-excess materials require the connection of crystal structure to electrochemical properties. In this dissertation, a combination of advanced characterization techniques was used as a tool to understand the intercalation mechanism of the layered lithium-excess transition metal oxide Li[NixLi1/3-2x/3Mn 2/3-x/3]O2. The research identified that synthesis influences the structure of the material specifically the surface of the particles. The formation of a hydroxide rich surface film decreases the electrochemical performance. Post synthesis modifications including high pressure and high temperature leads to the formation of a second layered phase in the bulk; however, the treated samples display good electrochemical properties. This result underlines the flexibility of the structure of Li[NixLi1/3-2x/3Mn 2/3-x/3]O2, a feature uncommon to other layered transition metal oxides. Surface characterization of the layered lithium-excess cathodes following electrochemical cycling revealed the formation of a new surface phase 1 to 5 nm thick as well as insight to the complex cation rearrangement process and phase transformation. This part of the research identified that significant changes occurred during electrochemical cycling; however did not identify when the transformations occurred. Investigation using in situ techniques during the first electrochemical cycle shows that the structure undergoes irreversible changes in lattice parameters and microstrain. Microstrain analysis shows that the material undergoes large increases in microstrain during the voltage plateau region. During the charging cycle, charge compensation mechanisms such as oxygen removal and cation migration accommodates the microstrain; however during discharge, these compensation mechanisms do not exist; therefore, causing the microstrain to increase. The analysis of structural changes before, during and following electrochemical property testing has led to an increased understanding of the lithium transport mechanisms in the lithium-excess series of materials.

  19. Layered double hydroxide-like materials: nanocomposites for use in concrete

    International Nuclear Information System (INIS)

    Nitrobenzoic acid (NBA), naphthalene-2, 6-disulfonic acid (26NS), and naphthalene-2 sulfonic acid (2NS) salts were intercalated into a layered double hydroxide-like host material (LDH). The intercalation process was achieved by anion exchange of nitrates in the host material, Ca2Al(OH)6NO3, nH2O (CaAl LDH), which was prepared by a coprecipitation technique. The resulting organo derivatives CaAlNBA LDH, CaAl26NS LDH, and CaAl2NS LDH produced a tilted orientation of NBA and 26NS anions in the interlayer space, while 2NS anions induced a perpendicular bilayer arrangement. Materials characterization was carried out using X-ray diffraction (XRD), IR-spectroscopy, thermal analysis, and scanning electron microscopy (SEM). These preliminary results open up a new direction towards the synthesis of nanocomposites using polymeric entities and layered materials for future applications in cement and concrete science, e.g., control of the effect of admixtures on the kinetics of cement hydration by programming their temporal release

  20. Preparation of thin layer materials with macroporous microstructure for SOFC applications

    International Nuclear Information System (INIS)

    A facile and versatile method using polymethyl methacrylate (PMMA) microspheres as pore formers has been developed to prepare thin layer oxide materials with controlled macroporous microstructure. Several mixed oxides with fluorite and perovskite-type structures, i.e. doped zirconia, ceria, ferrites, manganites, and NiO-YSZ composites have been prepared and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and mercury porosimetry. The synthesised materials are nanocrystalline and present a homogeneous pore distribution and relatively high specific surface area, which makes them interesting for SOFC and catalysis applications in the intermediate temperature range. - Graphical abstract: Thin films materials of mixed oxides with potential application in SOFC devices have been prepared with macroporous microstructure using PMMA microspheres as pore formers. Display Omitted

  1. Layered oxychalcogenide in the Bi-Cu-O-Se system as good thermoelectric materials

    Science.gov (United States)

    Barreteau, C.; Pan, L.; Amzallag, E.; Zhao, L. D.; Bérardan, D.; Dragoe, N.

    2014-06-01

    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.

  2. Surface reconstruction and chemical evolution of stoichiometric layered cathode materials for lithium-ion batteries

    Science.gov (United States)

    Lin, Feng; Markus, Isaac M.; Nordlund, Dennis; Weng, Tsu-Chien; Asta, Mark D.; Xin, Huolin L.; Doeff, Marca M.

    2014-03-01

    The present study sheds light on the long-standing challenges associated with high-voltage operation of LiNixMnxCo1-2xO2 cathode materials for lithium-ion batteries. Using correlated ensemble-averaged high-throughput X-ray absorption spectroscopy and spatially resolved electron microscopy and spectroscopy, here we report structural reconstruction (formation of a surface reduced layer, to transition) and chemical evolution (formation of a surface reaction layer) at the surface of LiNixMnxCo1-2xO2 particles. These are primarily responsible for the prevailing capacity fading and impedance buildup under high-voltage cycling conditions, as well as the first-cycle coulombic inefficiency. It was found that the surface reconstruction exhibits a strong anisotropic characteristic, which predominantly occurs along lithium diffusion channels. Furthermore, the surface reaction layer is composed of lithium fluoride embedded in a complex organic matrix. This work sets a refined example for the study of surface reconstruction and chemical evolution in battery materials using combined diagnostic tools at complementary length scales.

  3. Nanostructure and thermal stability of Co oxide multi-layer materials

    International Nuclear Information System (INIS)

    High-resolution microscopy and x-ray refraction were carried out for surveying thermal and environmental stability in nano-multi-layer materials, which are candidate for soft x-ray mirror materials. Co3O4/SiO2 nano-layer: This system shows excellent X-ray refraction property, and has a flat structure at nano-scale, where the thermal stability was high up to 600degC. Co3O4/BN nano-layer: This showed not enough x-ray refraction property, and has a nano-particle structure of Co3O4. Such difference may be caused by less wet-ability and chemical affinity. Thermal stability at high temperature up to 700-1000degC: The nano-particle structure in Co3O4/BN system up to 600degC, where such high stability consists with qualitative thermodynamic data, even if nano-scale particles. (author)

  4. Porous and Microporous Honeycomb Composites as Potential Boundary-Layer Bleed Materials

    Science.gov (United States)

    Davis, D. O.; Willis, B. P.; Schoenenberger, M.

    1997-01-01

    Results of an experimental investigation are presented in which the use of porous and microporous honeycomb composite materials is evaluated as an alternate to perforated solid plates for boundary-layer bleed in supersonic aircraft inlets. The terms "porous" and "microporous," respectively, refer to bleed orifice diameters roughly equal to and much less than the displacement thickness of the approach boundary-layer. A Baseline porous solid plate, two porous honeycomb, and three microporous honeycomb configurations are evaluated. The performance of the plates is characterized by the flow coefficient and relative change in boundary-layer profile parameters across the bleed region. The tests were conducted at Mach numbers of 1.27 and 1.98. The results show the porous honeycomb is not as efficient at removing mass compared to the baseline. The microporous plates were about equal to the baseline with one plate demonstrating a significantly higher efficiency. The microporous plates produced significantly fuller boundary-layer profiles downstream of the bleed region for a given mass flow removal rate than either the baseline or the porous honeycomb plates.

  5. Li-rich layer-structured cathode materials for high energy Li-ion batteries

    Science.gov (United States)

    Li, Liu; Lee, Kim Seng; Lu, Li

    2014-08-01

    Li-rich layer-structured xLi2MnO3 ? (1 - x)LiMO2 (M = Mn, Ni, Co, etc.) materials have attracted much attention due to their extraordinarily high reversible capacity as the cathode material in Li-ion batteries. To better understand the nature of this type of materials, this paper reviews history of development of the Li-rich cathode materials, and provides in-depth study on complicated crystal structures and reaction mechanisms during electrochemical charge/discharge cycling. Despite the fabulous capability at low rate, several drawbacks still gap this type of high-capacity cathode materials from practical applications, for instance the large irreversible capacity loss at first cycle, poor rate capability, severe voltage decay and capacity fade during electrochemical charge/discharge cycling. This review will also address mechanisms for these inferior properties and propose various possible solutions to solve above issues for future utilization of these cathode materials in commercial Li-ion batteries.

  6. 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.

  7. Understanding the Origin of Enhanced Performances in Core-Shell and Concentration-Gradient Layered Oxide Cathode Materials.

    Science.gov (United States)

    Song, Dawei; Hou, Peiyu; Wang, Xiaoqing; Shi, Xixi; Zhang, Lianqi

    2015-06-17

    Core-shell and concentration-gradient layered oxide cathode materials deliver superior electrochemical properties such as long cycle life and outstanding thermal stability. However, the origin of enhanced performance is not clear and seldom investigated until now. Here, a specific structured layered oxide (LiNi0.5Co0.2Mn0.3O2) consisting of concentration-gradient core, transition layer, and stable outer shell, is designed and achieved from double-shelled precursors to overcome the great challenge by comparison with the normal layered LiNi0.5Co0.2Mn0.3O2. As expected, the specific structured layered oxide displays excellent cycle life and thermal stability. After numerous cycles, the valence state of Ni and Co at normal layered oxide surface tends to a higher oxidation state than that of the specific structured oxide, and the spinel phase is observed on particle surface of normal layered oxide. Also, the deficient spinel/layered mixed phases lead to high surface film and charge-transfer resistance for normal layered oxide, whereas the specific structured one still remains a layered structure. Those results first illustrate the origin of improved electrochemical performance of layered core-shell and concentration-gradient cathode materials for lithium-ion batteries. PMID:26017733

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

    Science.gov (United States)

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

    2015-03-01

    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

  9. 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.

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

    Science.gov (United States)

    Zhuang, Chunqiang; Liu, Lei

    2015-03-01

    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.

  11. Functionalization of Fibers Using Azlactone-Containing Polymers: Layer-by-Layer Fabrication of Reactive Thin Films on the Surfaces of Hair and Cellulose-Based Materials

    OpenAIRE

    Buck, Maren E.; Lynn, David M.

    2010-01-01

    We report an approach to the functionalization of fibers and fiber-based materials that is based on the deposition of reactive azlactone-functionalized polymers and the ‘reactive’ layer-by-layer assembly of azlactone-containing thin films. We demonstrate (i) that the azlactone-functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) can be used to modify the surfaces of a model protein-based fiber (horsehair) and cellulose-based materials (e.g., cotton and paper), and (ii) that ...

  12. 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.

  13. A Method to Estimate the Dynamic Displacement and Stress of a Multi-layered Pavement with Bituminous or Concrete Materials

    Directory of Open Access Journals (Sweden)

    Zheng LU

    2014-12-01

    Full Text Available In this research work, a method to estimate the dynamic characteristics of a multilayered pavement with bituminous or concrete materials is proposed. A mechanical model is established to investigate the dynamic displacement and stress of the multi-layered pavement structure. Both the flexible and the rigid pavements, corresponding to bituminous materials and concrete materials, respectively, are studied. The theoretical solutions of the multi-layered pavement structure are deduced considering the compatibility condition at the interface of the structural layers. By introducing FFT (Fast Fourier Transform algorithm, some numerical results are presented. Comparisons of the theoretical and experimental result implied that the proposed method is reasonable in predicting the stress and displacement of a multi-layered pavement with bituminous or concrete materials. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6071

  14. Nanohybrid-layered double hydroxides/urease materials: Synthesis and application to urea biosensors

    International Nuclear Information System (INIS)

    Nanohybrid [ZnAl]-layered double hydroxides/urease were prepared for the first time using the coprecipitation of enzyme and inorganic matrix. By varying the respective amount of urease and LDH, we obtained hybrid materials with various amount and dispersion rate of active biomolecules. X-ray diffraction and infrared spectroscopy confirm the preservation of the structure of each partner while the morphology properties are in good agreement with the permeability study. These new nanohybrids were applied for the development of urea biosensors. Biosensor responses to urea additions were obtained using capacitance (C vs. V) measurements at urease-LDH biofilm deposited on an insulated semiconductor (IS) structure

  15. Defect physics, delithiation mechanism, and electronic and ionic conduction in layered lithium manganese oxide cathode materials

    OpenAIRE

    Hoang, Khang

    2014-01-01

    Layered LiMnO2 and Li2MnO3 are of great interest for lithium-ion battery cathodes because of their high theoretical capacities. The practical application of these materials is, however, limited due to poor electrochemical performance. We herein report a comprehensive first-principles study of defect physics in LiMnO2 and Li2MnO3 using hybrid density functional calculations. We find that manganese antisites have low formation energies in LiMnO2 and may act as nucleation sites...

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

    International Nuclear Information System (INIS)

    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

  17. 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.

  18. Los Alamos MAWST software layered on Westinghouse Savannah River Company's nuclear materials accountability system

    International Nuclear Information System (INIS)

    The Los Alamos Safeguards Systems Group's Materials Accounting With Sequential Testing (MAWST) computer program was developed to fulfill DOE Order 5633.3B requiring that inventory-difference control limits be based on variance propagation or any other statistically valid technique. Westinghouse Savannah River Company (WSRC) developed a generic computerized accountability system, NucMAS, to satisfy accounting and reporting requirements for material balance areas. NucMAS maintains the calculation methods and the measurement information required to compute nuclear material transactions in elemental and isotopic masses by material type code. The Safeguards Systems Group designed and implemented to WSRC's specifications a software interface application, called NucMASloe. It is a layered product for NucMAS that automatically formats a NucMAS data set to a format compatible with MAWST and runs MAWST. This paper traces the development of NucMASloe from the Software Requirements through the testing and demonstration stages. The general design constraints are described as well as the difficulties encountered on interfacing an external software product (MAWST) with an existing classical accounting structure (NucMAS). The lessons learned from this effort, the design, and some of the software are directly applicable to the Local Area Network Material Accountability System (LANMAS) being sponsored by DOE

  19. Study on UV-shielding mechanism of layered double hydroxide materials.

    Science.gov (United States)

    Shi, Wenying; Lin, Yanjun; Zhang, Shitong; Tian, Rui; Liang, Ruizheng; Wei, Min; Evans, David G; Duan, Xue

    2013-11-01

    The development of UV-shielding materials has attracted considerable attention in the field of coatings and sunscreen. This paper reports the UV-shielding mechanism of layered double hydroxide (LDH) materials in terms of chemical composition, structure and morphology, by using (LDH/PAA)n films (n stands for bilayer number) through alternate LBL assembly of LDH nanoparticles and poly(acrylic acid) (PAA) on quartz substrates as a model system. A combination investigation based on experimental and theoretical study demonstrates that the maximum UV scattering can be achieved when ?/d ? 1.98; the introduction of Zn element is an effective way to tune the electron structure, band gap, transition mode and resulting UV-shielding property of LDH materials. A UV-shielding efficiency as high as 95% can be obtained by modulating the particle size, composition and thickness of the LDHs. Furthermore, the UV anti-aging capacity of LDH-modified bitumen was studied, which demonstrates a large improvement in UV-resistance performance of bitumen by the incorporation of LDH materials. Therefore, this work systematically discloses the relationship between UV-shielding property and chemical/structural parameters of LDH materials, which can be potentially used as anti-aging agents in various organic matrices and polymer areas. PMID:24064552

  20. Material and Doping Dependence of the Nodal and Anti-Nodal Dispersion Renormalizations in Single- and Multi-Layer Cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, S.; /Waterloo U. /SLAC; Lee, W.S.; /Stanford U., Geballe Lab. /SLAC; Nowadnick, E.A.; /SLAC /Stanford U., Phys. Dept.; Moritz, B.; /SLAC /North Dakota U.; Shen, Z.-X.; /Stanford U., Geballe Lab. /SLAC /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Devereaux, T.P.; /Stanford U., Geballe Lab. /SLAC

    2010-02-15

    In this paper we present a review of bosonic renormalization effects on electronic carriers observed from angle-resolved photoemission spectra in the cuprates. Specifically, we discuss the viewpoint that these renormalizations represent coupling of the electrons to the lattice and review how materials dependence, such as the number of CuO{sub 2} layers, and doping dependence can be understood straightforwardly in terms of several aspects of electron-phonon coupling in layered correlated materials.

  1. Automatic identification of single- and/or few-layer thin-film material

    DEFF Research Database (Denmark)

    Jessen, Bjarke SØrensen Technical University of Denmark,

    One or more digital representations of single- (101) and/or few-layer (102) thin- film material are automatically identified robustly and reliably in a digital image (100), the digital image (100) having a predetermined number of colour components, by - determining (304) a background colour component of the digital image (100) for each colour component, and - determining or estimating (306) a colour component of thin-film material to be identified in the digital image (100) for each colour component by obtaining a pre-determined contrast value (C R; C G; C B) for each colour component and multiplying the respective bacground colour component with a numerical difference between the pre-determined contrast value (C R; C G; C B) for a given colour component and about 1, - identifying points or parts of the image with all colour components being within a predetermined range of the determined or estimated colour component.

  2. 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.

  3. 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)

  4. Sputtered platinum-iridium layers as electrode material for functional electrostimulation

    Energy Technology Data Exchange (ETDEWEB)

    Ganske, G., E-mail: ganske@iwe1.rwth-aachen.d [Institute of Materials in Electrical Engineering I, RWTH Aachen University, Sommerfeldstr. 24, D-52074 Aachen (Germany); Slavcheva, E. [Institute of Materials in Electrical Engineering I, RWTH Aachen University, Sommerfeldstr. 24, D-52074 Aachen (Germany); Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Ooyen, A. van; Mokwa, W.; Schnakenberg, U. [Institute of Materials in Electrical Engineering I, RWTH Aachen University, Sommerfeldstr. 24, D-52074 Aachen (Germany)

    2011-03-31

    In this study co-sputtered layers of platinum-iridium (PtIr) are investigated as stimulation electrode material. The effects of different sputter parameters on the morphology and the electrochemical behavior are examined. It is shown that films sputtered at the lowest incident energy possess the highest charge storage capacity (CSC). At a Pt:Ir atomic-ratio of 55:45 the obtained CSC of 22 mC/cm{sup 2} is enhanced compared to the standard stimulation material platinum (16 mC/cm{sup 2}) but inferior to iridium which has a CSC of 35 mC/cm{sup 2}. Long term cyclic voltammetry measurements show that PtIr can be activated which increases the CSC to 29 mC/cm{sup 2}. Also a change in the film morphology is observed. Sputtered platinum-iridium films promise to combine high mechanical strength and increased charge storage capacity.

  5. OPTIMIZING A PORTABLE MICROWAVE INTERFERENCE SCANNING SYSTEM FOR NONDESTRUCTIVE TESTING OF MULTI-LAYERED DIELECTRIC MATERIALS

    International Nuclear Information System (INIS)

    The projected microwave energy pattern, wave guide geometry, positioning methods and process variables have been optimized for use of a portable, non-contact, lap-top computer-controlled microwave interference scanning system on multi-layered dielectric materials. The system can be used in situ with one-sided access and has demonstrated capability of damage detection on composite ceramic armor. Specimens used for validation included specially fabricated surrogates, and ballistic impact-damaged specimens. Microwave data results were corroborated with high resolution direct-digital x-ray imaging. Microwave interference scanning detects cracks, laminar features and material properties variations. This paper presents the details of the system, the optimization steps and discusses results obtained.

  6. Electrochemical Effects of Atomic Layer Deposition on Cathode Materials for Lithium Batteries

    Science.gov (United States)

    Scott, Isaac David

    One of the greatest challenges of modern society is to stabilize a consistent energy supply that will meet our growing energy demand while decreasing the use of fossil fuels and the harmful green house gases which they produce. Developing reliable and safe solutions has driven research into exploring alternative energy sources for transportation including fuel cells, hydrogen storage, and lithium-ion batteries (LIBs). For the foreseeable future, though, rechargeable batteries appear to be the most practically viable power source. To deploy LIBs in next-generation vehicles, it is essential to develop electrodes with durability, high energy density, and high power. Unfortunately, the power capability of LIBs is generally hindered by Li+-ion diffusion in micrometer-sized materials and the formation of an insulating solid electrolyte interface (SEI) layer on the surface of the active material. In addition, degradation of the battery material due to chemical and electrochemical reactions with the electrolyte lead to both capacity fade and safety concerns both at room and higher temperatures. The current study focuses on mitigating these issues for high voltage cathode materials by both using nanoscale particles to improve Li+-ion diffusion and using ultrathin nanoscale coatings to protect the battery materials from undesirable side reactions. The electrode material is coated with Al2O3 using atomic layer deposition (ALD), which is a method to grow conformal thin films with atomic thickness (angstrom level control) using sequential, self-limiting surface reactions. First, nano-LiCoO 2 is employed to demonstrate the effectiveness of ALD coatings and demonstrates a profound increase in rate performance (>250% improvement) over generally employed micrometer-sized particles. Second, the cathode materials LiNi 0.8Co0.15Al0.05O2, LiNi0.33Mn 0.33Co0.33O2, LiMn2O4, and LiNi0.5Mn1.5O4 were used to demonstrate the benefits ALD coatings have on thermal runaway. The results show a decrease in exothermic reactions at elevated temperatures (>180 °C) for the coated versus uncoated material. Third, impedance studies were carried out on LiNi0.5Mn1.5O 4 to study the kinetic effects the ALD layer has on battery performance. These studies show that despite Al2O3 being electrically resistive in the bulk; the ultrathin coatings do not impede battery reaction kinetics. Finally, ALD coatings were studied for use in Li-O2 batteries. The results from these studies provide new opportunities for the battery industry to design other novel electrodes that are highly durable, safe, and provide good power performance. It also demonstrates that many of the issues that are detrimental to LIBs may simply be addressed by employing the scalable technique of atomic layer deposition.

  7. Novel magnetic materials prepared by electrodeposition techniques: arrays of nanowires and multi-layered microwires

    International Nuclear Information System (INIS)

    The fabrication process by electrodeposition routes and the study of general magnetic properties is reported for two types of nanostructured magnetic materials: (a) nickel-filled highly-ordered nanoporous alumina templates, and (b) electrodeposited Ni layers onto glass coated amorphous microwires. Arrays of Ni nanowires, about 30 nm in diameter and separated by about 100 nm, are obtained by electrodeposition into the pores of alumina membranes prepared by two-steps anodization process from highly pure aluminum substrates. Morphological studies have been performed by high resolution scanning electron microscopy (HRSEM). The study includes the optimization of preparation parameters and the magnetic characterization of the hexagonally arranged nanowire arrays, i.e. the influence of the pore diameter and the interwire distance on the coercivity of the whole nanowire array. On the other hand, multi-layered magnetic microwires have been prepared in the following sequence: a nanometric Au coat is first sputtered onto Pyrex coated FeSiB amorphous microwires followed by electrodeposition of a 500 nm thick Ni external cover. While in as-cast microwires the hysteresis loop is squared shaped (magnetic bistability), in the case of the multilayer microwire, a transverse magnetic anisotropy is induced when reducing the measuring temperature as a consequence of the stresses induced by the different thermal expansion coefficients of the various layerss layers

  8. Emergency sacrificial sealing method in filters, equipment, or systems

    Science.gov (United States)

    Brown, Erik P

    2014-09-30

    A system seals a filter or equipment component to a base and will continue to seal the filter or equipment component to the base in the event of hot air or fire. The system includes a first sealing material between the filter or equipment component and the base; and a second sealing material between the filter or equipment component and the base and proximate the first sealing material. The first sealing material and the second seal material are positioned relative to each other and relative to the filter or equipment component and the base to seal the filter or equipment component to the base and upon the event of fire the second sealing material will be activated and expand to continue to seal the filter or equipment component to the base in the event of hot air or fire.

  9. Selective electroless nickel deposition on copper as a final barrier/bonding layer material for microelectronics applications

    Science.gov (United States)

    Rohan, James F.; O'Riordan, Gerald; Boardman, Jane

    2002-01-01

    A low cost, selective electroless metallisation of integrated circuit (IC) copper bond pads with nickel and gold is demonstrated. This metallurgy can function as a barrier layer/bondable material when deposited as a thin layer or as the chip bump for flip chip applications when deposited to greater heights. Four alternative activation steps for selective electroless nickel deposition on bond pad copper are demonstrated. Selective low cost deposition has been achieved with a proprietary electroless plating bath developed at NMRC and three commercial baths on both sputtered copper substrates and electrolessly deposited copper on titanium nitride barrier layer material.

  10. Rediscovering black phosphorus as an anisotropic layered material for optoelectronics and electronics

    Science.gov (United States)

    Xia, Fengnian; Wang, Han; Jia, Yichen

    2014-07-01

    Graphene and transition metal dichalcogenides (TMDCs) are the two major types of layered materials under intensive investigation. However, the zero-bandgap nature of graphene and the relatively low mobility in TMDCs limit their applications. Here we reintroduce black phosphorus (BP), the most stable allotrope of phosphorus with strong intrinsic in-plane anisotropy, to the layered-material family. For 15-nm-thick BP, we measure a Hall mobility of 1,000 and 600?cm2?V-1?s-1 for holes along the light (x) and heavy (y) effective mass directions at 120?K. BP thin films also exhibit large and anisotropic in-plane optical conductivity from 2 to 5??m. Field-effect transistors using 5?nm BP along x direction exhibit an on-off current ratio exceeding 105, a field-effect mobility of 205?cm2?V-1?s-1, and good current saturation characteristics all at room temperature. BP shows great potential for thin-film electronics, infrared optoelectronics and novel devices in which anisotropic properties are desirable.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J.P.; McDevitt, J.T. [Univ. of Texas, Austin, TX (United States). Dept. of Chemistry and Biochemistry; Jia, Q. [Los Alamos National Lab., NM (United States). Superconductivity Technology Center

    1997-09-01

    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 R{sub 1{minus}x}Ca{sub x}Ba{sub 2{minus}y}La{sub y}Cu{sub 3{minus}z}M{sub z}O{sub 7{minus}{delta}} (R = Y, Gd and Pr; M = Co, Ni and Zn; 0 < x < 0.4; 0 < y < 0.4; 0 < z < 0.4) have been developed using a crystal engineering approach. The lattice structure of the new N-layer compounds displays a high compatibility with the parent YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} phase and the modified materials exhibit enhanced durability properties. The compounds have been utilized to make both SNS junctions and SQUID devices.

  12. Crystallization of amorphous silicon thin films using nanoenergetic intermolecular materials with buffer layers

    Science.gov (United States)

    Lee, Choong Hee; Jeong, Tae Hoon; Kim, Do Kyung; Jeong, Woong Hee; Kang, Myung-Koo; Hwang, Tae Hyung; Kim, Hyun Jae

    2009-02-01

    Optimization of the crystallization of amorphous silicon (a-Si) using a mixture of nanoenergetic materials of iron oxide/aluminum (Fe 2O 3/Al) was studied. To achieve high-quality polycrystalline Si (poly-Si) thin films, silicon oxide (SiO 2) and silver (Ag) layer were deposited on the a-Si as buffer layers to prevent the metal diffusion in a-Si during thermite reaction and to transport the thermal energy released from nanoenergetic materials, respectively. Raman measurement was used to define the crystallinity of poly-Si. For molar ratio of Al and Fe of 2 with 100-nm-thick-SiO 2, Raman measurement showed the 519.59 cm -1 of peak position and the 5.08 cm -1 of full width at half maximum with 353 MPa of low tensile stress indicating high quality poly-Si thin film. These results showed that optimized thermite reaction could be used successfully in crystallization of a-Si to high -quality poly-Si thin films.

  13. 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

  14. Alternative material to mitigate chrome degradation on high volume ArF layers

    Science.gov (United States)

    Ning, Guoxiang; Gopalakrishnan, Selvi; Thamm, Thomas; Oleynik, Nikolay; Ackmann, Paul; Riviere, Remi; Maelzer, Stephanie; Foong, Yee Mei

    2013-09-01

    One of the objectives of a robust optical proximity correction (OPC) model is to simulate the process variation including 3D mask effects or mask models for different mask blanks. Assuming that the data of different reticle blanks is the same, the wafer data should be a close match for the same OPC model. In order to enhance the robustness of the OPC model, the 3D mask effects need to be reduced. A test of this would be to ensure a close match of the so called fingerprints of different reticle blanks at the wafer level. Features for fingerprint test patterns include "critical dimension through pitch" (CDTP), "inverse CDTP", and "linearity patterns" and critical dimension (CD) difference of disposition structures. In this manuscript the proximity matching of implant layers on chrome on glass (COG) and advance binary reticle blanks will be demonstrated. We will also investigate the influence of reticle blank material including reticle process on isolated and dense features upon the proximity matching for 28 nm high volumes ArF layers such as implant and 2X metal layers. The OPC model verification has been done successfully for both bare wafer and full field wafer for implant layers. There is comparable OPC model for advanced binary and COG reticle. Moreover, the wafer critical dimension uniformity (CDU) results show that advance binary has much better wafer CDU then COG. In spite of higher reticle cost when switching over to advanced binary, there is a considerable cost reduction for the wafer fab which includes a 39% savings in total reticle cost as well as cost reduction due to minimal line holds (LH), wafer reworks and scraps due to Chrome degradation.

  15. SYNTHESIS AND ADSORPTION CHARACTERISTIC OF HUMIC/MGAL LAYERED DOUBLE HYDROXIDE HYBRID MATERIALS

    Directory of Open Access Journals (Sweden)

    XIAOQIAN LIU

    2010-12-01

    Full Text Available Two synthetic routes, coprecipitation and adsorption, for the incorporation of humic acid and Mg-Al layered double hydroxide (MgAl-LDH were investigated and two kinds of dark brown Humic / MgAl-LDH hybrid materials were synthesized. X-ray Diffraction (XRD, Fourier Transform Infrared Spectroscopy (FTIR, thermogravimetric analysis (TGA, total organic carbon (TOC and elemental analysis show that the stable humic anions contents in the prepared materials are 10.84% (w w-1 and 5.88% (w w-1 from coprecipitation, adsorption process, respectively, and humic anions rather bond with exposed hydrated metal ions on the subsurface of fine LDH particles than intercalate into the interlayer space. Via coprecipitation method, a Humic/LDH hybrid material with finer particle size and higher humic carbon content can be obtain. Further aqueous Zn(II adsorption experiment showed that it was a kind of favorable humic material with much higher Zn (II adsorption capacity, 181 mg g-1, than that of ordinary adsorbents in literature.

  16. Neutron diffraction study of thermal residual strain in three layered materials made by self-propagating high-temperature synthesis

    International Nuclear Information System (INIS)

    The thermal residual strain in the three layered materials, [WC-10mass%Ni]-[Ni]-[WC-10mass%Ni], [WC-10mass%Ni]-[SUS304(plate)]-[WC-10mass%Ni] and [WC-10mass%Ni]-[Ni(plate)]-[WC-10mass%Ni], has been investigated by neutron diffraction measurement. They were made by self-propagating high-temperature synthesis. Original materials of composite [WC-10mass%Ni] are powders of W, C and Ni, and those of the middle layers are the powders of Ni, a plate of SUS304 and a plate of Ni. The samples were 40mm in diameter and about 4mm in thickness of each layer. The result of the measurement shows that the middle layer made from powders of Ni has no strain, which suggests that it shrinks from high temperature freely from the existence of both side layers. On the other hand, the middle layer made from a plate material experiences complex stress according to each position and to each direction of the sample, which suggests that it shrinks from high temperature in a state of tight binding on both side layers. The Ni region in the composite material, [WC-10mass%Ni], has a large tensile strain of 0.6 to 1.0%, whereas WC region has a negligibly small compressive strain. In this case, the Ni region shrinks under the hard connection with the WC region, of which the thermal expansion coefficient is relatively small. (author)

  17. Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template

    Directory of Open Access Journals (Sweden)

    Ludovic F. Dumee

    2014-08-01

    Full Text Available Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm as well as the sintering pressure (5–20 ton·m?2 and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested.

  18. Hydrofracture pattern formation during central air injection in granular materials confined in thin layers.

    Science.gov (United States)

    Toussaint, R.; Maloy, K. J.; Flekkoy, E. G.; Johnssen, O.

    2003-04-01

    Fluid injection in a granular material confined in thin layers leads to the formation of high permability channels very localized, where fluids flow preferrentially. This phenomenon is of primary importance for the understanding the role of fluids overpressures and leakage in saturated lowly consolidated gouges or sedimentary rock layers between cap-rocks in the presence of localized fluid sources. In an analogous model, we investigate the pattern formation during central air injection in a metric Hele-Shaw cell consisting of two metric glass plates with fixed 1mm separation filled with fine compacted granular material - glass beads from 70 to 150 microns diameter. In a loosely compacted material between horizontal plates, air is injected in the center at constant pressure of a few bar percents. This leads to the formation of wide fingers empty of grains analous to viscous fingering in the central region, followed by thin branching fingers and eventually very localized displacement structures analogous to brittle cracks further away from the injection point. Fluid drag is balanced by the friction exerted by the confining cell, a compacted region being observed to grow indepth in front of the fingers as they propagate. The geometry and dynamics of these structures are characterized as function of the injection pressure. We also investigate this phenomenon using a coupled granular/fluid flow simulation model, where quasi two dimensional granular columns are submitted to fluid pressure gradients, central repulsive contact forces and Coulomb friction along the confining walls, while the fluid obeys a Darcy equation whose permeability is set by a coarse grained local solid fraction. The main features of the experimental patterns are so recovered and studied.

  19. 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 undersco external construct architecture underscoring its potential to generate customized implants for human tissue regeneration. (paper)

  20. Cleaning of conveyor belt materials using ultrasound in a thin layer of water.

    Science.gov (United States)

    Axelsson, L; Holck, A; Rud, I; Samah, D; Tierce, P; Favre, M; Kure, C F

    2013-08-01

    Cleaning of conveyor belts in the food industry is imperative for preventing the buildup of microorganisms that can contaminate food. New technologies for decreasing water and energy consumption of cleaning systems are desired. Ultrasound can be used for cleaning a wide range of materials. Most commonly, baths containing fairly large amounts of water are used. One possibility to reduce water consumption is to use ultrasonic cavitation in a thin water film on a flat surface, like a conveyor belt. In order to test this possibility, a model system was set up, consisting of an ultrasound transducer/probe with a 70-mm-diameter flat bottom, operating at 19.8 kHz, and contaminated conveyor belt materials in the form of coupons covered with a thin layer of water or water with detergent. Ultrasound was then applied on the water surface at different power levels (from 46 to 260 W), exposure times (10 and 20 s), and distances (2 to 20 mm). The model was used to test two different belt materials with various contamination types, such as biofilms formed by bacteria in carbohydrate- or protein-fat-based soils, dried microorganisms (bacteria, yeasts, and mold spores), and allergens. Ultrasound treatment increased the reduction of bacteria and yeast by 1 to 2 log CFU under the most favorable conditions compared with water or water-detergent controls. The effect was dependent on the type of belt material, the power applied, the exposure time, and the distance between the probe and the belt coupon. Generally, dried microorganisms were more easily removed than biofilms. The effect on mold spores was variable and appeared to be species and material dependent. Spiked allergens were also efficiently removed by using ultrasound. The results in this study pave the way for new cleaning designs for flat conveyor belts, with possibilities for savings of water, detergent, and energy consumption. PMID:23905796

  1. Synthesis of polyaniline/carbon black hybrid hollow microspheres by layer-by-layer assembly used as electrode materials for supercapacitors

    International Nuclear Information System (INIS)

    Graphical abstract: The polyaniline/carbon black hybrid hollow microspheres with a external diameter about 3.0 ?m were prepared via layer-by-layer assembly technique, and the electrochemical tests showed that polyaniline/carbon black hybrid hollow microspheres would be a potential candidates of electrode materials for supercapacitors with high specific capacitance. Highlights: ? The PAn/CB hybrid hollow microspheres were prepared via LBL technique. ? The specific capacitance increased with the increase in the adsorption of PAn and CB. ? The hollow structure and synergistic effect of shell enhance the specific capacitance. ? The PAn/CB hollow microsphere is a candidate of electrode material for supercapacitor. -- Abstract: The polyaniline (PAn)/carbon black (CB) hybrid hollow microspheres have been prepared by the layer-by-layer assembly technique alternately adsorbing of PAn and CB onto the polystyrene sulfonate microsphere templates after etching the templates by dialysis. The hollow structure of the obtained hybrid hollow microspheres was characterized by transmission electron microscopy, which indicated that the external diameter of the hollow microspheres was about 3.0 ?m. When the hybrid hollow microsphere were used as the electrode material for supercapacitors, the results showed that the specific capacitance increased with the increase in the adsorption numbers of PAn and CB, which was as high as 532 F g?1 at a charge–discharge current density of 10 mA cm?2 in 1.0 M H2SO4 electrolyte after alternately adsorbing of PAn and CB six times

  2. Fluorine uptake into the human tooth from a thin layer of F-releasing material

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, H. [Department of Restorative Dentistry and Endodontology, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka, 565-0871 (Japan)]. E-mail: yhiroko@dent.osaka-u.ac.jp; Nomachi, M. [Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043 (Japan); Yasuda, K. [Wakasa Wan Energy Research Center, Tsuruga, Fukui, 914-0192 (Japan); Iwami, Y. [Department of Restorative Dentistry and Endodontology, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka, 565-0871 (Japan); Ebisu, S. [Department of Restorative Dentistry and Endodontology, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka, 565-0871 (Japan); Komatsu, H. [Graduate School of Dental Medicine, Hokkaido University, Sapporo, Hokkaido, 060-8585 (Japan); Sakai, T. [Advanced Radiation Technology Center, JAERI, Takasaki, Gunma, 370-1292 (Japan); Kamiya, T. [Advanced Radiation Technology Center, JAERI, Takasaki, Gunma, 370-1292 (Japan)

    2007-07-15

    Using the proton induced gamma-ray emission (PIGE) method (TIARA, Japan), we have studied fluorine (F) distribution in the human tooth under various conditions. Here, we report F uptake into the human tooth from a thin layer of F-releasing low viscous resin (FLVR). Crowns of human teeth were horizontally cut and the dentin of the cut surface was first covered with four kinds of FLVR (FL-Bond, Reactmer Bond, Xeno Bond, and Protect Liner F; thickness, 50-150 {mu}m) according to the manufacturers' instructions. Non-F-releasing and F-releasing filling resins were also hardened, on the cut surfaces of crowns covered with four kinds of FLVR thin layers. The type of the non-F-releasing filling materials used was LITE FIL IIP: G1-A (FL-Bond and LITE FIL IIP), G2-A (Reactmer Bond and LITE FIL IIP), G3-A (Xeno Bond and LITE FIL IIP), and G4-A (Protect Liner F and LITE FIL IIP). The types of F-releasing filling materials used were G1-B (FL-Bond and Beautifil), G2-B (Reactmer Bond and Reactmer Paste), G3-B (Xeno Bond and Xeno CF Paste), and G4-B (Protect Liner F and Teethmate F-1). Treatment and measurements of specimens were the same as previously reported [H. Yamamoto, M. Nomahci, K. Yasuda, Y. Iwami, S. Ebisu, N. Yamamoto, T. Sakai, T. Kamiya, Nucl. Instr. and Meth. B 210 (2003) 388]. F uptake from specimens following one month of application was estimated from 2-D maps. F penetration was observed in all teeth of G1-A-G4-A groups. The maximum values of F concentration in each tooth and F penetration depth were larger for larger F concentrations in FLVR. FLVR was useful for the F uptake into the tooth, and the F distribution near the thin layer of FLVR depended on the materials used. Between G1-A and G1-B or G4-A and G4-B, the F uptake was significantly different. We were able to obtain fundamental data, which were useful for the analysis of F transportation relating to prevention of caries.

  3. Fluorine uptake into the human tooth from a thin layer of F-releasing material

    International Nuclear Information System (INIS)

    Using the proton induced gamma-ray emission (PIGE) method (TIARA, Japan), we have studied fluorine (F) distribution in the human tooth under various conditions. Here, we report F uptake into the human tooth from a thin layer of F-releasing low viscous resin (FLVR). Crowns of human teeth were horizontally cut and the dentin of the cut surface was first covered with four kinds of FLVR (FL-Bond, Reactmer Bond, Xeno Bond, and Protect Liner F; thickness, 50-150 ?m) according to the manufacturers' instructions. Non-F-releasing and F-releasing filling resins were also hardened, on the cut surfaces of crowns covered with four kinds of FLVR thin layers. The type of the non-F-releasing filling materials used was LITE FIL IIP: G1-A (FL-Bond and LITE FIL IIP), G2-A (Reactmer Bond and LITE FIL IIP), G3-A (Xeno Bond and LITE FIL IIP), and G4-A (Protect Liner F and LITE FIL IIP). The types of F-releasing filling materials used were G1-B (FL-Bond and Beautifil), G2-B (Reactmer Bond and Reactmer Paste), G3-B (Xeno Bond and Xeno CF Paste), and G4-B (Protect Liner F and Teethmate F-1). Treatment and measurements of specimens were the same as previously reported [H. Yamamoto, M. Nomahci, K. Yasuda, Y. Iwami, S. Ebisu, N. Yamamoto, T. Sakai, T. Kamiya, Nucl. Instr. and Meth. B 210 (2003) 388]. F uptake from specimens following one month of application was estimated from 2-D maps. F penetration was observed in all teeth of G1-A-G4-A groups. The maximum values of F concentration in each toimum values of F concentration in each tooth and F penetration depth were larger for larger F concentrations in FLVR. FLVR was useful for the F uptake into the tooth, and the F distribution near the thin layer of FLVR depended on the materials used. Between G1-A and G1-B or G4-A and G4-B, the F uptake was significantly different. We were able to obtain fundamental data, which were useful for the analysis of F transportation relating to prevention of caries

  4. Effect of Alclad Layer on Material Flow and Defect Formation in Friction-Stir-Welded 2024 Aluminum Alloy

    Science.gov (United States)

    Zhang, Z.; Xiao, B. L.; Wang, D.; Ma, Z. Y.

    2011-06-01

    The effect of the Alclad layer on material flow and defect formation during friction-stir welding (FSW) of 6.5-mm-thick 2024Al-T351 alloy plates was investigated. To characterize the material flow during FSW, different cross sections of the keyhole and "stop-action weld" were made for metallographic observations. It was found that the top Alclad assembled at the shoulder/workpiece interface, thereby weakening the material flow in the shoulder-driven zone and favoring the formation of void defect at high traveling speeds. The bottom Alclad layer extended into the weld at excess material flow state, which could be avoided at balanced material flow state. A conceptual model of material flow was proposed to describe the formation of the weld. It was indicated that a perfect FSW joint of Alclad 2024Al alloy without defect could be obtained at an optimum FSW condition.

  5. Development of nano cerium oxide incorporated aluminium alloy sacrificial anode for marine applications

    International Nuclear Information System (INIS)

    Aluminium-zinc alloy sacrificial anodes are extensively used for cathodic protection. The performance of the sacrificial anodes can be significantly improved by incorporation of microalloying elements in the aluminium matrix. In the present work nano cerium oxide particles of different concentrations, ranging from 0 to 1 wt% were incorporated for activating and improving the performance of the anode. The electrochemical test results revealed the increased efficiency of the anode. The electrochemical impedance spectroscopy revealed the information that the presence of nano cerium oxide in the anode matrix caused effective destruction of the passive alumina film, which facilitated enhancement of galvanic performance of the anode. Moreover, the biocidal activity of cerium oxide prevented the bio accumulation considerably which enables the anodes to be used in aggressive marine conditions

  6. Sacrificial Microchannel Sealing by Glass-Frit Reflow for Chip Scale Atomic Magnetometer

    Science.gov (United States)

    Tsujimoto, Kazuya; Hirai, Yoshikazu; Sugano, Koji; Tsuchiya, Toshiyuki; Tabata, Osamu

    A novel sealing technique using sacrificial microchannels was proposed for atmosphere control in a micromachined alkali gas-filled cell for a chip scale atomic magnetometer. The microchannels act as feedthrough connecting the cell to outside atmosphere during evacuation and gas-filling steps, and eventually they are sealed by glass-frit reflow. Si microchannel dedicated as a sacrificial microchannel was proposed and its feasibility was successfully demonstrated by experiments. The simulation results clarified the glass-frit reflow characteristics and its dependence on cross-sectional shape of the microchannel. Hermeticity of the proposed sealing technique of less than 10-12Pa·m3/s leak rate was verified by a high resolution helium leak test.

  7. 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.

  8. 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.

  9. 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 eag 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

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

    OpenAIRE

    Michael D. Blanton; James W. Rawlins; Shashi S. Pathak; Sharathkumar K. Mendon

    2012-01-01

    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 ...

  11. 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.

  12. 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)

  13. Improved description of soft layered materials with van der Waals density functional theory

    International Nuclear Information System (INIS)

    The accurate description of van der Waals forces within density functional theory is currently one of the most active areas of research in computational physics and chemistry. Here we report results on the structural and energetic properties of graphite and hexagonal boron nitride, two layered materials where interlayer binding is dominated by van der Waals forces. Results from several density functionals are reported, including the optimized Becke88 van der Waals (optB88-vdW) and the optimized PBE van der Waals (optPBE-vdW) (Klimeš et al 2010 J. Phys.: Condens. Matter 22 022201) functionals. Where comparison to experiment and higher-level theory is possible, the results obtained from the two new van der Waals density functionals are in good agreement. An analysis of the physical nature of the interlayer binding in both graphite and hexagonal boron nitride is also reported.

  14. Highly Stable and Luminescent Layered Hybrid Materials for Sensitive Detection of TNT Explosives.

    Science.gov (United States)

    Xiao, Fang-Nan; Wang, Kang; Wang, Feng-Bin; Xia, Xing-Hua

    2015-04-21

    Self-assembly is an effective way to fabricate optical molecular materials. However, this strategy usually changes the nanoenvironment surrounding fluorescence molecules, yielding low luminescence efficiency. Herein, we report the intercalation of a ruthenium polypyridine (Ru) complex into the interlayer galleries of layered double hydroxides (LDHs), forming a Ru/LDH hybrid. The Ru complex exists as an ordered monolayer state, and the hybrid exhibits high thermal and photo stability. Its luminescence efficiency and lifetime are increased by ?1.7 and ?1 times, respectively, compared to those of free molecules. We constructed a Ru/LDH sensing platform based on a fluorescence quenching effect for highly sensitive detection of TNT with a detection limit of 4.4 ?M. PMID:25817704

  15. Layered and intercalated hydrotalcite-like materials as thermal stabilizers in PVC resin

    Science.gov (United States)

    Lin, Yanjun; Wang, Jianrong; Evans, David G.; Li, Dianqing

    2006-05-01

    In the light of the accepted mechanism of thermal stabilization of PVC by layered double hydroxides (LDHs), the layer cations and interlayer counterions in LDHs were tailored to give MgZnAl-CO3-LDH and MgZnAl-maleate-LDH. These materials were characterized by XRD, FT-IR, and TG DTA. The thermal stability of PVC composites containing different LDH additives was tested in sheets having a thickness of about 1 mm. The results showed that compared with MgAl-CO3-LDH, MgZnAl-CO3-LDH enhances the thermal stability of PVC in terms of both long-term stability and early coloring. After intercalation of maleate in the LDH by reaction of maleic acid with the MgZnAl-CO3-LDH precursor, the interlayer distance increases from 0.75 to 1.11 nm. Since Cl- promotes the autocatalytic dehydrochlorination of PVC, which is responsible for its degradation, an increased interlayer distance should facilitate entry of Cl- into the interlayer galleries and inhibit the decomposition of PVC. In addition, maleic acid has a conjugated C=C double bond which can react with double bond formed in the dehydrochlorination of PVC and thus further inhibit the autocatalytic degradation reaction. The results show that the early coloring of PVC is markedly improved and the long-term stability slightly reduced by addition of the MgZnAl-maleate-LDH.

  16. Oscillatory motion in layered materials: graphene, boron nitride, and molybdenum disulfide.

    Science.gov (United States)

    Ye, Zhijiang; Otero-de-la-Roza, Alberto; Johnson, Erin R; Martini, Ashlie

    2015-04-24

    Offset-driven self-retraction and oscillatory motion of bilayer graphene has been observed experimentally and is potentially relevant for nanoscale technological applications. In a previous article, we showed that friction between laterally offset graphene layers is controlled by roughness and proposed a simple reduced-order model based on density-functional theory (DFT) and molecular dynamics (MD) data, with which predictions on the experimental size-scale could be made. In this article, we extend our study to other layered materials, with emphasis on boron nitride (BN) and molybdenum disulfide (MoS2). Using MD and DFT simulations of these systems and a generalized version of the reduced-order model, we predict that BN will exhibit behavior similar to graphene (heavily-damped oscillation with a decay rate that increases with roughness) and that MoS2 shows no oscillatory behavior even in the absence of roughness. This is attributed to the higher energy barrier for sliding in MoS2 as well as the surface structure. Our generalized reduced-order model provides a guide to predicting and tuning experimental oscillation behavior using a few parameters that can be derived from simulation data. PMID:25815685

  17. Oscillatory motion in layered materials: graphene, boron nitride, and molybdenum disulfide

    Science.gov (United States)

    Ye, Zhijiang; Otero-de-la-Roza, Alberto; Johnson, Erin R.; Martini, Ashlie

    2015-04-01

    Offset-driven self-retraction and oscillatory motion of bilayer graphene has been observed experimentally and is potentially relevant for nanoscale technological applications. In a previous article, we showed that friction between laterally offset graphene layers is controlled by roughness and proposed a simple reduced-order model based on density-functional theory (DFT) and molecular dynamics (MD) data, with which predictions on the experimental size-scale could be made. In this article, we extend our study to other layered materials, with emphasis on boron nitride (BN) and molybdenum disulfide (MoS2). Using MD and DFT simulations of these systems and a generalized version of the reduced-order model, we predict that BN will exhibit behavior similar to graphene (heavily-damped oscillation with a decay rate that increases with roughness) and that MoS2 shows no oscillatory behavior even in the absence of roughness. This is attributed to the higher energy barrier for sliding in MoS2 as well as the surface structure. Our generalized reduced-order model provides a guide to predicting and tuning experimental oscillation behavior using a few parameters that can be derived from simulation data.

  18. '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

  19. The behaviour of selected material/oxide layer systems with change of temperature loading

    International Nuclear Information System (INIS)

    In this work, the behaviour of material/oxide layer systems with isothermal and thermal cycling stresses was examined in detail on the example of X 20 CrMoV 12 1, alloy 800 H (X 10 NiCrAlTi 32 20) and HK 40 (G-X 40 CrNiSi 25 20) steels. The materials were in the form of heat exchanger pipes and some of them were bar material. The change of temperature loading was defined by the parameter temperature of the isothermal stopping phase, maximum cooling load, duration of the isothermal stopping phase and the value of the cooling speed. The parameters for the individual materials were as follows: X 20 CrMoV 12 1:650deg C, 350deg-250deg C, 4-24 hours, 10degC/min; Alloy 800 H: 900degC, 650deg-800deg C, 12-48 hours, 25degC/min; HK 40: 950deg C, 750deg C, 12-48 hours, 25degC/min. The compliance of the parameters was controlled by a personal computer, which was used to record sound emission measurements. The analysis of sound signals on the heat exchanger pipes, similar to components, or on bars should give information on the time of occurrence and the type of oxidation damage. The experiments were carried out in air, air + 0.5% SO2 and for X 20 CrMoV 12 1 also with an (Ar + 5% H2) + 50% H2O gas mixture on the inside of the heat exchanger pipes. (orig./MM)

  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. On the mechanism of oxide layer formation on surfaces of structural materials in aqueous medium at high temperatures and protective properties of such layers

    International Nuclear Information System (INIS)

    In high-temperature water a magnetite layer is formed on steel that inhibits further corrosion of the matrix material. Complexon treatment has proved a success for purposeful and more rapid formation of such a protective layer. During the first step of that treatment iron complexonates are formed at temperatures of about 1500C which are decomposed by thermolysis in the following step at a temperature of 2900C and higher yielding a magnetite layer on the steel surface. With this, special requirements arise for both the state of metallic surface and the reaction conditions. Analogically to thermolytic decomposition of the complexonates, a radiolytical decomposition is also possible. Complexon treatment with a view to increasing corrosion resistance is also applicable to various metals present in a system. Deposition on the corresponding matrix takes place according to Dankov's principle of structural equality. Complexon treatment has special importance for zirconium alloys to prevent hydrogen absorption. (author)

  2. Formation of accessory mineral bed layers during erosion of bentonite buffer material

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. dilute groundwater at a transmissive fracture interface, accessory phases within bentonite, such as quartz, feldspar, etc., might remain behind and form a filter bed or cake. As more and more montmorillonite is lost, the thickness of the accessory mineral bed increases and the continued transport of montmorillonite slows and possibly stops if the porosity of the filter bed is sufficiently compressed. Alternatively or concurrently, as the accessory mineral filter bed retains montmorillonite colloids, a filter cake composed of montmorillonite itself may be formed. Ultimately, depending on their extent, properties, and durability, such processes may provide the bentonite buffer system with an inherent, self-filtration mechanism which serves to limit the effects of colloidal erosion. A conceptual view of bentonite buffer extrusion and erosion in an intersecting fracture with formation of an accessory mineral filter bed and montmorillonite filter cake is presented in Figure 1. Due to the swelling pressure of the bentonite buffer, the situation described in Figure 1 may be analogous to that of the case of pressure filtration where a filter cake is formed by pressing a suspension through a filter medium and, by a mechanism known as expression, the filter cake is compressed by direct contact with a solid surface resulting in a reduction of its porosity. In order to examine whether the erosion of bentonite material through con erosion of bentonite material through contact with dilute groundwater at a transmissive fracture interface could intrinsically result in 1) the formation of an accessory mineral filter bed and cake and/or 2) filter caking of montmorillonite itself, a series of laboratory tests were performed in a flow-through, horizontal, 1 mm aperture, artificial fracture system. Bentonite buffer material was simulated by using mixtures (75/25 weight percent ratio) of purified sodium montmorillonite and various additives serving as accessory mineral proxies (kaolin, quartz sand, chromatographic silica). The resulting mixtures were compacted into dense sample tablets with effective montmorillonite dry densities between 1.4 to 1.6 g/cm3. The fracture erosion tests were performed using a Grimsel groundwater simulant (relative to Na+ and Ca2+ concentration only) contact solution at an average flow rate of 0.09 ml/min through the system. In colloid filtration theories, the filter bed is modelled as an assemblage of single or unit collectors having a known geometry. According to Richards [2010], the particle size distribution of the accessory minerals in MX-80 bentonite consists of particles with sizes less than 30 ?m. Of the additive materials used in this study, the kaolin material consists of particles with sizes less than 20 ?m showing a peak size of 6 ?m, the chromatographic silica consists of particles with sizes narrowly distributed between 10 to 14 ?m, and the sand consists of particles with sizes between 160 to 550 ?m at a peak size of 280 ?m. The tests were designed to lead to the development of erosive conditions (i.e., sodium montmorillonite against a dilute solution) and, in every case, the formation of an accessory mineral bed layer near the extrusion/erosion interface was observed. Moreover, these layers grew progressively in thickness over the course of the tests. These results provide evidence that, following erosive loss of colloidal montmorillonite through contact with dilute groundwater at a transmissive fracture interface, accessory phases (within bentonite) remain behind and form bed layers

  3. Hybrid Materials Based on Magnetic Layered Double Hydroxides: A Molecular Perspective.

    Science.gov (United States)

    Abellán, Gonzalo; Martí-Gastaldo, Carlos; Ribera, Antonio; Coronado, Eugenio

    2015-06-16

    Design of functional hybrids lies at the very core of synthetic chemistry as it has enabled the development of an unlimited number of solids displaying unprecedented or even improved properties built upon the association at the molecular level of quite disparate components by chemical design. Multifunctional hybrids are a particularly appealing case among hybrid organic/inorganic materials. Here, chemical knowledge is used to deploy molecular components bearing different functionalities within a single solid so that these properties can coexist or event interact leading to unprecedented phenomena. From a molecular perspective, this can be done either by controlled assembly of organic/inorganic molecular tectons into an extended architecture of hybrid nature or by intercalation of organic moieties within the empty channels or interlamellar space offered by inorganic solids with three-dimensional (MOFs, zeolites, and mesoporous hosts) or layered structures (phosphates, silicates, metal dichalcogenides, or anionic clays). This Account specifically illustrates the use of layered double hydroxides (LDHs) in the preparation of magnetic hybrids, in line with the development of soft inorganic chemistry processes (also called "Chimie Douce"), which has significantly contributed to boost the preparation hybrid materials based on solid-state hosts and subsequent development of applications. Several features sustain the importance of LDHs in this context. Their magnetism can be manipulated at a molecular level by adequate choice of constituting metals and interlayer separation for tuning the nature and extent of magnetic interactions across and between planes. They display unparalleled versatility in accommodating a broad range of anionic species in their interlamellar space that encompasses not only simple anions but chemical systems of increasing dimensionality and functionalities. Their swelling characteristics allow for their exfoliation in organic solvents with high dielectric strength, to produce two-dimensional nanosheets with atomic thickness that can be used as macromolecular building blocks in the assembly of nanocomposites. We describe how these advantageous properties turn LDHs into excellent vehicles for the preparation of multifunctional materials with increasing levels of complexity. For clarity, the reader will first find a succinct description of the most relevant aspects controlling the magnetism of LDHs followed by their use in the preparation of magnetic hybrids from a molecular perspective. This includes the intercalation anionic species of increasing nuclearity like paramagnetic mononuclear complexes, stimulus-responsive molecular guests, one- and two-dimensional coordination polymers, or even preassembled 2D networks. This approach allows us to evolve from "dual-function" materials with coexistence, for example, of magnetism and superconductivity, to smart materials in which the magnetic or structural properties of the LDH layers can be tuned by applying an external stimulus like light or temperature. We will conclude with a brief look into the promising features offered by magnetic nanocomposites based on LDHs and our views on the most promising directions to be pursued in this context. PMID:25989182

  4. Synthesis of organo-mineral nanohybrid material: indole-2-carboxylate in the lamella of Zn-Al-layered double hydroxide

    International Nuclear Information System (INIS)

    An organo-mineral nanohybrid material in which the organic moiety is interleaved inside the inorganic lamella was prepared by using indole-2-carboxylate anions as a guest in the Zn-Al-layered double hydroxide lamella, as an inorganic host by a self-assembly technique. Powder X-ray diffractogram of the material shows that the basal spacing of the Zn-Al-layered double hydroxide with nitrate as the counter anion expanded from 8.8 to around 18.2 Angst in the resulting nanohybrid material. FTIR studies show that the absorption bands of the resulting materials correspond to the characteristic functional groups of the host and the guest. When the two data are taken together, the expansion can be attributed to the intercalation of the organic moiety, indole-2-carboxylate anion in the inorganic interlamella for the formation of the nanohybrid material

  5. Structure and mechanical properties of the three-layer material based on a vanadium alloy and corrosion-resistant steel

    Science.gov (United States)

    Nikulin, S. A.; Rozhnov, A. B.; Nechaikina, T. A.; Rogachev, S. O.; Zavodchikov, S. Yu.; Khatkevich, V. M.

    2014-10-01

    The quality of three-layer pipes has been studied; they are manufactured by hot pressing of a three-layer assembly of tubular billets followed by forging and cold rolling. The operating core is made from a V-4Ti-4Cr alloy. The protective claddings are made from corrosion-resistant steels of two grades, 08Kh17T and 20Kh13. The results of investigation into the structure and microhardness of the junction zone of steel and the vanadium alloy, which includes a contact zone and a transition diffusion layer, are reported. The 08Kh17T steel is shown to be a preferred cladding material.

  6. Electrochemical investigation of Li-excess layered oxide cathode materials/mesocarbon microbead in 18650 batteries

    International Nuclear Information System (INIS)

    The electrochemical performance of the 18650 lithium-ion batteries for layered Li-excess oxide Li1.144Ni0.136Co0.136Mn0.544O2(LNCMO) cathode material and mesocarbon microbead (MCMB) anode material is investigated. The battery shows an excellent rate capability with the capacity of 227 mAh g?1 at 8 C-rate (the cut-off voltage is 4.5 V). Furthermore, it exhibits excellent cycle performance that the capacity retention over 300 cycles in the voltage ranges of 2.5-4.5 V (vs. MCMB) and at 0.2 C-rate is about 85%. Although the medium voltage of the battery greatly reduces during the first 30 cycles, it keeps stable in the following cycles. The mechanisms of the capacity fade and voltage decay are also studied based on energy dispersive spectrometry, X-ray photoelectron spectroscopy, charge-discharge curves, and dQ/dV plots

  7. Dependences of optical properties of spherical two-layered nanoparticles on parameters of gold core and material shell

    International Nuclear Information System (INIS)

    Modeling of nonlinear dependences of optical properties of spherical two-layered gold core and some material shell nanoparticles (NPs) placed in water on parameters of core and shell was carried out on the basis of the extended Mie theory. Efficiency cross-sections of absorption, scattering and extinction of radiation with wavelength 532 nm by core–shell NPs in the ranges of core radii r00=5–40 nm and of relative NP radii r1/r00=1–8 were calculated (r1—radius of two-layered nanoparticle). Shell materials were used with optical indexes in the ranges of refraction n1=0.2–1.5 and absorption k1=0–3.5 for the presentation of optical properties of wide classes of shell materials (including dielectrics, metals, polymers, vapor shell around gold core). Results show nonlinear dependences of optical properties of two-layered NPs on optical indexes of shell material, core r00 and relative NP r1/r00 radii. Regions with sharp decrease and increase of absorption, scattering and extinction efficiency cross-sections with changing of core and shell parameters were investigated. These dependences should be taken into account for applications of two-layered NPs in laser nanomedicine and optical diagnostics of tissues. The results can be used for experimental investigation of shell formation on NP core and optical determination of geometrical parameters of core and shell of two-layered NPs. -- Highlights: • Absorption, scattering and extinction of two-layered nanoparticles are studied. • Shell materials change in wide regions of materials (metals, dielectrics, vapor). • Effect of sharp decrease and increase of optical characteristics is established. • Explanation of sharp decreasing and increasing optical characteristics is presented

  8. Deterministic physical and mathematical models of coupled heat, moisture and salt transport in multi-layered systems of building materials

    Science.gov (United States)

    Ko?í, Václav; Mad?ra, Ji?í; ?erný, Robert

    2013-10-01

    Several models of coupled heat, moisture and salt transport in multi-layered systems of building materials are analyzed and theirstrong and weak points are discussed. As a result of this analysis, a compromise between sophisticated buttoo complex models which are characterized by excessive demands on input material parameters and oversimplified models giving only approximate results is chosen. The practical applicability of the selected model is illustrated on an example of coupled heat, moisture and salt transport in sandstone wall provided with surface layers on both interior and exterior side.

  9. COMPARATIVE STUDY OF STRESSES AND STRAINS THAT OCCUR IN STRUCTURAL ELEMENTS MADE OF COMPOSITE MATERIALS CONSIDERING THE MODEL WITH AND WITHOUT LAYERS

    Directory of Open Access Journals (Sweden)

    FLORENTINA TOCU

    2012-12-01

    Full Text Available Fibreglass-reinforced polyester (GRP is the most widely used composite material in the ship building industry and requires careful study in point of mechanical characteristics. This article presents the collective experience related to behaviour in different situations of GRP loading. We considered three cases manufacturing for GRP: layers with mechanical characteristics for each layer, composite (the material is considered isotropic but with layers and same mechanical properties for all layers, and isotropic plates.

  10. Compound surface-plasmon-polariton waves guided by a thin metal layer sandwiched between a homogeneous isotropic dielectric material and a periodically multilayered isotropic dielectric material

    CERN Document Server

    Chiadini, Francesco; Scaglione, Antonio; Lakhtakia, Akhlesh

    2015-01-01

    Multiple p- and s-polarized compound surface plasmon-polariton (SPP) waves at a fixed frequency can be guided by a structure consisting of a metal layer sandwiched between a homogeneous isotropic dielectric (HID) material and a periodic multilayered isotropic dielectric (PMLID) material. For any thickness of the metal layer, at least one compound SPP wave must exist. It possesses the p-polarization state, is strongly bound to the metal/HID interface when the metal thickness is large but to both metal/dielectric interfaces when the metal thickness is small. When the metal layer vanishes, this compound SPP wave transmutes into a Tamm wave. Additional compound SPP waves exist, depending on the thickness of the metal layer, the relative permittivity of the HID material, and the period and the composition of the PMLID material. Some of these are p polarized, the others being s polarized. All of them differ in phase speed, attenuation rate, and field profile, even though all are excitable at the same frequency. The...

  11. Characterization of the Minimum Effective Layer of Thermal Insulation Material Tow-plaster from the Method of Thermal Impedance

    OpenAIRE

    Ould Brahim, M. S.; I Diagne, S. Tamba

    2011-01-01

    Our objective in this study is to determine the effective thermal insulating layer of a composite towplaster. The characterization of thermal insulating material is proposed from the study of the thermal impedance in dynamic two-dimensional frequency. Thermo physical properties of the material tow-plaster are determined from the study of the thermal impedance. Nyquist representations have introduced an interpretation of certain phenomena of heat transfer from the series and shunt resistors. T...

  12. Novel approach to material evaluation of thin surface layers by resonant ultrasound spectroscopy

    International Nuclear Information System (INIS)

    The laser-based modal resonant ultrasound spectroscopy is modified for measurements of thin surface layers on a substrate. This paper describes determination of all in-plane elastic properties of thin layers from small resonant frequency shifts of substrate induced by deposition of the layer.

  13. Coincident Doppler broadening measurement on embedded thin layers of different materials with a positron beam of variable energy

    International Nuclear Information System (INIS)

    Coincident Doppler broadening (CDB) is particularly suited to study thin layers in a non-destructive way. Further, CDB is outstanding in its sensitivity to defects and precipitates, because the positron is used as a ''nanoprobe''. It diffuses thermally inside the sample, can be localized at a defect and then annihilates with an electron by the emission of gamma-radiation. The shape of the annihilation line is characteristic for chemical elements and defect types. Defects have a highly attractive potential for the diffusing positron, which leads to trapping in open volume defects. But also the trapping at precipitates and small clusters of a different material is possible. The aim of the presented experiment is to study the trapping at interfaces and thin layers. For this purpose, samples consisting of aluminum are grown with an embedded layer of gold, copper and chrome. These materials cover a wide range of positron affinities, so the trapping probability of a positron at the layer depends on the material and the layer thickness. CDBS-results of these samples are presented and explained by a one-dimension potential well model.

  14. Microstructural characterisation of a prototype layer structure for a GaN-based photonic crystal cavity

    International Nuclear Information System (INIS)

    A semiconductor multilayer consisting of an n-type GaN/sapphire pseudo-substrate with a double sacrificial layer (20 nm of InGaN and 20 nm of InAlN) and a GaN cavity structure on top incorporating an InGaN quantum dot active layer was grown. Atomic force microscopy (AFM) was used to measure the morphology of the upper surface of each layer of similar test structures and to assess the morphological evolution of the full structure during its growth. Transmission electron microscopy (TEM) was also used to assess defect incorporation into the structure. AFM showed that the incorporation of a double sacrificial layer was observed to have no detrimental affect on either the formation of the quantum dots, or the morphology of the top GaN capping layer. TEM highlighted the occurrence of threading dislocations propagating through the sacrificial layers into the capping GaN layer, but did not resolve the occurrence of defect generation in the sacrificial layers.

  15. Electroluminescence and impedance analyses of organic light emitting diodes using anhydride materials as cathode interfacial layers

    International Nuclear Information System (INIS)

    Pyromellitic dianhydride (PMDA) and trimellitic anhydride (TMA) were tried as cathode interfacial layers between tris-(8-hydroxyquinoline) aluminum (Alq3) and Al in organic light emitting diodes (OLEDs). Both ultra-thin anhydride cathode interfacial layers improved the electroluminescence characteristics of OLEDs compared to those without any interfacial layer, and the PMDA interfacial layer showed the most significant enhancement of the device performance. According to impedance measurements and equivalent circuit analysis, the PMDA interfacial layer decreased the impedance, probably due to the increase in the injection efficiency of electrons from the Al cathode.

  16. Toward a stabilized lattice framework and surface structure of layered lithium-rich cathode materials with Ti modification.

    Science.gov (United States)

    Wang, Sihui; Li, Yixiao; Wu, Jue; Zheng, Bizhu; McDonald, Matthew J; Yang, Yong

    2015-04-21

    Layered lithium-rich oxides have several serious shortcomings such as fast voltage fading and poor cyclic stability of energy density which greatly hinder their practical applications. Fabrication of a stable framework of layered lithium-rich oxides during charging-discharging is crucial for addressing the above problems. In this work, we show that Ti modification is a promising way to realize this target with bifunctional roles. For example, it is able to substitute Mn in the lattice framework and form a stable surface layer. It therefore leads to an improved retention of energy density of the Ti-modified Li1.2Mn0.54-xTixNi0.13Co0.13O2 (x = 0.04, 0.08, and 0.15) materials during cycling. The evolution of dQ/dV curves show that the layered/spinel phase transformation is suppressed owing to the introduction of strong Ti-O bonds in the framework. In addition, SEM, TEM, and EIS results confirm that a more uniform and stable interface layer is formed on Ti-modified Li1.2Mn0.54-xTixNi0.13Co0.13O2 (x = 0.04, 0.08, and 0.15) materials compared with the Ti-free counterpart. The stable interface layer on the lithium-rich oxides is also beneficial for further reducing side reactions, resulting in stable interface layer resistance. Therefore, the improved cycling performance of the material is due to both contribution of the more stable framework and enhanced electrode/electrolyte interface by Ti modification. PMID:25790778

  17. 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

  18. 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).

  19. 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.

  20. New PACVD-hard material layers for wear protection of high-speed steel

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, K.; Leonhardt, A. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Langer, U.; Kuenanz, K. [Technische Universitaet Dresden, Institut fuer Produktionstechnik, D-01062, Dresden (Germany)

    1997-10-01

    TiC/C, (Ti,Al)N and (Ti,Al)C layers have been deposited employing PACVD under dc-pulse discharge conditions and were investigated with respect to their composition and structure. The layer hardness can be varied in a large range by varying the Al content and the C content in the case of the TiC/C layers. By incorporation of C in TiC layers the friction coefficient can be decreased. Analogously to TiN layers, oxygen impurities cause a drastic hardness decrease in (Ti,Al)N layers. It was demonstrated that by multilayer deposition including TiN, TiCN and (Ti,Al)N with single layers of 100-300 nm thickness the layer stress decreases by about 50%, which results in an increase in layer adhesion. PACVD (Ti,Al)N and TiC/C layers yielded comparable or even better results than PVD layers in drilling 41Cr4 steel and the Al-alloy AlSi9Cu3. (orig.) 11 refs.

  1. Dependence of structure and temperature for lithium-rich layered-spinel microspheres cathode material of lithium ion batteries

    Science.gov (United States)

    Wang, Di; Yu, Ruizhi; Wang, Xianyou; Ge, Long; Yang, Xiukang

    2015-02-01

    Homogeneous lithium-rich layered-spinel 0.5Li2MnO3.0.5LiMn1/3Ni1/3Co1/3O2 microspheres (~1 ?m) are successfully prepared by a solvothermal method and subsequent high-temperature calcinations process. The effects of temperature on the structure and performance of the as-prepared cathode material are systemically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), galvanostatical charge/discharge and electrochemical impedance spectra. The results show that a spinel Li4Mn5O12 component can be controllably introduced into the lithium-rich layered material at 750°C. Besides, it has been found that the obtained layered-spinel cathode material represents excellent electrochemical characteristics. For example, it can deliver a high initial discharge capacity of 289.6 mAh g-1 between 2.0 V and 4.6 V at a rate of 0.1 C at room temperature, and a discharge capacity of 144.9 mAh g-1 at 5 C and 122.8 mAh g-1 even at 10 C. In addition, the retention of the capacity is still as high as 88% after 200 cycles, while only 79.9% for the single-phase layered material. The excellent electrochemical performance of the as-prepared cathode material can probably be attributed to the hybrid structures combining a fast Li-ion diffusion rate of 3D spinel Li4Mn5O12 phase and a high capacity of the layered Li-Mn-Ni-Co-O component.

  2. Dependence of structure and temperature for lithium-rich layered-spinel microspheres cathode material of lithium ion batteries.

    Science.gov (United States)

    Wang, Di; Yu, Ruizhi; Wang, Xianyou; Ge, Long; Yang, Xiukang

    2015-01-01

    Homogeneous lithium-rich layered-spinel 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 microspheres (~1??m) are successfully prepared by a solvothermal method and subsequent high-temperature calcinations process. The effects of temperature on the structure and performance of the as-prepared cathode material are systemically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), galvanostatical charge/discharge and electrochemical impedance spectra. The results show that a spinel Li4Mn5O12 component can be controllably introduced into the lithium-rich layered material at 750°C. Besides, it has been found that the obtained layered-spinel cathode material represents excellent electrochemical characteristics. For example, it can deliver a high initial discharge capacity of 289.6?mAh g(-1) between 2.0?V and 4.6?V at a rate of 0.1 C at room temperature, and a discharge capacity of 144.9?mAh g(-1) at 5 C and 122.8?mAh g(-1) even at 10 C. In addition, the retention of the capacity is still as high as 88% after 200 cycles, while only 79.9% for the single-phase layered material. The excellent electrochemical performance of the as-prepared cathode material can probably be attributed to the hybrid structures combining a fast Li-ion diffusion rate of 3D spinel Li4Mn5O12 phase and a high capacity of the layered Li-Mn-Ni-Co-O component. PMID:25672573

  3. Design considerations for electrode buffer layer materials in polymer solar cells.

    Science.gov (United States)

    Bilby, David; Frieberg, Bradley; Kramadhati, Shobhita; Green, Peter; Kim, Jinsang

    2014-09-10

    Electrode buffer layers in polymer-based photovoltaic devices enable highly efficient devices. In the absence of buffer layers, we show that diode rectification is lost in ITO/P3HT:PCBM/Ag (ITO = indium tin oxide; P3HT = poly(3-hexylthiophene); PCBM = phenyl C61-butyric acid methyl ester) devices due to nonselective charge injection through the percolated phase pathways of a bulk heterojunction active layer. Charge-selective injection, and thus rectification and device function, can be regained by placing thin, polymeric buffer layers that break the direct electrode-active layer contact. Additionally, we show that strong active layer-buffer layer interactions lead to unwanted vertical phase separation and a kinked current-voltage curve. Device function is regained, increasing power conversion efficiency from 3.6% to 7.2%, by placing a noninteracting layer between the buffer and active layer. These results guide the design and selection of future polymeric electrode buffer layers for efficient polymer solar cell devices. PMID:25116039

  4. Low pull-in voltage graphene electromechanical switch fabricated with a polymer sacrificial spacer

    Science.gov (United States)

    Sun, Jian; Wang, Wenzhen; Muruganathan, Manoharan; Mizuta, Hiroshi

    2014-07-01

    A simple bottom-up procedure using a polymer sacrificial spacer is presented to fabricate graphene electromechanical contact switch devices without using acid etching. Low pull-in voltage of below 2 V is achieved with good consistency on a run-to-run basis, which is compatible with the conventional, complementary metal-oxide-semiconductor circuit requirements. In addition, the formation of carbon-gold bonds at the contact position is proposed as another important mechanism for the irreversible switch—other than the well-known irreversible static friction.

  5. Formation of upper rim acylated calix[4]arenes using a sacrifici al zinc anode

    OpenAIRE

    Louati, Alain; Vataj, Rame; Gabelica, Valérie; Lejeune, Manuel; Matt, Dominique

    2005-01-01

    A straightforward electrosynthetic method is described, which allows upper rim acylation of non-p-halogenated calix[4]-arenes. For example, a solution of tetrapropoxycalix[4]arene 4 was electrolysed in the presence of ZnBr2, in an undivided cell fitted with a sacrificial zinc anode using pure acetonitrile as solvent, yielding an organozinc species, which was then treated with acetyl chloride in the presence of a palladium catalyst to afford 5,11-diacety1-25,26,27,28-tetrapropoxycalix[4]arene ...

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

    OpenAIRE

    Carabat, A. L.; Zwaag, S.; 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...

  7. Sacrificial CVD film etch-back process for air-gap Cu interconnects

    International Nuclear Information System (INIS)

    A novel sacrificial chemical vapor deposition film etch-back process for Cu air-gap interconnects was developed. The etched-back Cu surfaces were analyzed by X-ray photoelectron spectroscopy. The electrical characteristics and the stress induced voiding reliability were evaluated. The CF4 etch-back process was found not to degrade interconnect reliability. A four-level dual damascene Cu interconnect structure was successfully fabricated, and its effective dielectric constant was 2.8, 32% lower than that of a conventionally fabricated one. In situ N2 or Ar plasma treatments after etch-back were investigated to reduce the Cu degradation

  8. 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

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

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

    Capasso, A.; De Francesco, M.; Leoni, E.; Dikonimos, T.; Buonocore, F.; Lancellotti, L.; Bobeico, E.; Sarto, M. S.; Tamburrano, A.; De Bellis, G.; Lisi, N.

    2014-09-01

    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.

  11. 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.

  12. 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.

  13. Deterministic transfer of two-dimensional materials by all-dry viscoelastic stamping

    Science.gov (United States)

    Castellanos-Gomez, Andres; Buscema, Michele; Molenaar, Rianda; Singh, Vibhor; Janssen, Laurens; van der Zant, Herre S. J.; Steele, Gary A.

    2014-06-01

    The deterministic transfer of two-dimensional crystals constitutes a crucial step towards the fabrication of heterostructures based on the artificial stacking of two-dimensional materials. Moreover, controlling the positioning of two-dimensional crystals facilitates their integration in complex devices, which enables the exploration of novel applications and the discovery of new phenomena in these materials. To date, deterministic transfer methods rely on the use of sacrificial polymer layers and wet chemistry to some extent. Here, we develop an all-dry transfer method that relies on viscoelastic stamps and does not employ any wet chemistry step. This is found to be very advantageous to freely suspend these materials as there are no capillary forces involved in the process. Moreover, the whole fabrication process is quick, efficient, clean and it can be performed with high yield.

  14. Results of Tests with Large Sacrificial and Self-Cleaning Strainers and the installation at Ringhals 2

    International Nuclear Information System (INIS)

    The paper describes briefly activities performed by Vattenfall Utveckling AB at Alvkarleby Laboratory as part of the qualification programme for the new ECCS strainers at PWR plant Ringhals 2 based on the 'robust solution' with large sacrificial strainers and a self-cleaning 'wing-strainer' of same type as used for the five modified Swedish BWR plants. With the new knowledge gained from several BWR strainer projects following the BarseNick strainer incident in 1992, the functioning of ECCS strainers for PWR was re-evaluated. The upgrading at Ringhals 2, a 3-loop Westinghouse plant having fiberglass and mineral wool as insulation, was the result of a design study including a lot of experimental work mainly in 1993 and 1994. The new ECC system was installed in 5 days in the summer outage 1995. In a first study in year 1993 in the large test tank at Alvkarleby Laboratory it was discovered that the earlier design basis for debris settlement was not fulfilled. Recirculating water falling from a large break will not only prevent settling of the fibrous insulation debris but also disintegrate wads and larger pieces to fibres and fines. It could no longer be assumed that the insulation would settle in front of the strainers. This discovery affected the further work within the project group and the work at Alvkarleby Laboratory. It is presented some test data that have not been published before, e.g. combinations of fibres and particulate material. The test programme included ate material. The test programme included also chemical treated fibrous insulation as well as combinations with carbon powder or oil. Also experiences from combinations of fibres and RMI debris were gained. Some information from projects later performed for the US market are included. Also it is included some experience on deviations in results when tests are performed in different ways. At the end the modified strainer system for Ringhals 2 is presented. (author)

  15. Effect of interface layers on phase-change recording material analyzed by hard X-ray photoelectron spectroscopy method

    International Nuclear Information System (INIS)

    The influence of interface layers on the chemical and electronic states of a phase-change recording material, GeBiTe (GBT) alloy, used in high-speed rewritable HD DVD media was investigated for the first time by hard-X-ray photoelectron spectroscopy (HX-PES). The binding state of elements for the amorphous state of the phase-change recording film with interface layers is closer to that of the crystalline state than the amorphous film without interface layers. The density of states (DOS) for the valence band of the amorphous state without an interface layer was smaller than that of the crystalline state. The band-edge energy of the amorphous state without an interface layer was lower than that of the crystalline state by about 0.5eV. On the other hand, the DOS and the band-edge energy of the amorphous state of GBT with interface layers were almost the same as those of the crystalline state. This result may lead to almost the same carrier for electrical conduction for the crystalline state as the amorphous state, which is totally unexpected, thus very interesting, because the atomic arrangements should differ from each other. We speculate that these effects are a factor allowing high-speed crystallization. (author)

  16. Broadband nonlinear optical response in multi-layer black phosphorus: an emerging infrared and mid-infrared optical material.

    Science.gov (United States)

    Lu, S B; Miao, L L; Guo, Z N; Qi, X; Zhao, C J; Zhang, H; Wen, S C; Tang, D Y; Fan, D Y

    2015-05-01

    Black phosphorous (BP), the most thermodynamically stable allotrope of phosphorus, is a high-mobility layered semiconductor with direct band-gap determined by the number of layers from 0.3 eV (bulk) to 2.0 eV (single layer). Therefore, BP is considered as a natural candidate for broadband optical applications, particularly in the infrared (IR) and mid-IR part of the spectrum. The strong light-matter interaction, narrow direct band-gap, and wide range of tunable optical response make BP as a promising nonlinear optical material, particularly with great potentials for infrared and mid-infrared opto-electronics. Herein, we experimentally verified its broadband and enhanced saturable absorption of multi-layer BP (with a thickness of ~10 nm) by wide-band Z-scan measurement technique, and anticipated that multi-layer BPs could be developed as another new type of two-dimensional saturable absorber with operation bandwidth ranging from the visible (400 nm) towards mid-IR (at least 1930 nm). Our results might suggest that ultra-thin multi-layer BP films could be potentially developed as broadband ultra-fast photonics devices, such as passive Q-switcher, mode-locker, optical switcher etc. PMID:25969214

  17. Protein-mediated layer-by-layer synthesis of TiO?(B)/anatase/carbon coating on nickel foam as negative electrode material for lithium-ion battery.

    Science.gov (United States)

    Wang, Xiaobo; Yan, Yong; Hao, Bo; Chen, Ge

    2013-05-01

    Through an aqueous, protein-mediated layer-by-layer titania deposition process, we have fabricated a protamine/titania composite layer on nickel foam. The coating was composed of amorphous carbon and TiO2(B)/anatase nanoparticles and formed upon organic pyrolysis under a reducing atmosphere (5% H2-Ar mixture). X-ray diffraction analyses, Auger electron spectroscopy, and high-resolution transmission electron microscopy revealed that the obtained coatings contained fine monoclinic TiO2(B) and anatase nanocrystals, along with amorphous carbon. Moreover, the coating can be used as a binder-free negative electrode material for lithium-ion batteries and exhibits high reversible capacity and fast charge-discharge properties; a reversible capacity of 245 mAh g(-1) was obtained at a current density of 50 mA g(-1), and capacities of 167 and 143 mAh g(-1) were obtained at current densities of 1 and 2 A g(-1), respectively. PMID:23597025

  18. 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)

  19. 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.

  20. 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.

  1. 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 structured channels. Thefabricated 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 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.

  2. 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.

  3. Shape-selective sieving layers on an oxide catalyst surface

    Science.gov (United States)

    Canlas, Christian P.; Lu, Junling; Ray, Natalie A.; Grosso-Giordano, Nicolas A.; Lee, Sungsik; Elam, Jeffrey W.; Winans, Randall E.; van Duyne, Richard P.; Stair, Peter C.; Notestein, Justin M.

    2012-12-01

    New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al2O3 (thickness, 0.4-0.7 nm) with ‘nanocavities’ (TiO2 photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations.

  4. 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

  5. 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.

  6. 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

  7. 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%.

  8. 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

    2015-01-01

    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 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

  9. 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.

  10. Test of Capsule (11M-22K) with Double Layered Thermal Media for Irradiation of Future Nuclear System Materials

    International Nuclear Information System (INIS)

    By the irradiation test, the structural integrity and safety of the capsule during irradiation at high temperature were confirmed. The outlet temperatures of VHTR and SFR are 1,000 .deg. C and 550 .deg. C, respectively, which are much higher than the irradiation temperatures of the material capsules tested at HANARO up to recently. The capsule for high-temperature materials was designed as a double layered thermal media, in which the outer layer is aluminum and the inner layer is Ti or graphite. This capsule aims at allowing irradiation at temperatures of up to 1,000 .deg. C in the near future. As future nuclear systems are to be operated at high temperatures, the irradiation tests at high temperature are necessary. In accordance with this requirement, a capsule suitable for an irradiation test at high temperatures is being developed to overcome a restriction on the use of aluminum at high temperature. A new capsule with thermal media of a double layered structure, the outer of which is Al and the inner is Ti or graphite, was designed. This capsule was applied to an irradiation test up to 900 .deg. C. The capsule for use at the irradiation test up to 1,000 .deg. C will be developed at the beginning in 2014

  11. Laser modification of properties of the surface layer of conducting materials

    Science.gov (United States)

    Kostrubiec, Franciszek; Pawlak, Ryszard; Walczak, Maria

    2003-10-01

    This paper presents the results of modification of surface layer properties, obtained the optimised laser alloying of metals insignificant in electrical engineering. Systems with continous, quasi-continuous and pulsed laser beams and different wave lengths were used in the experiments. The structure and composition of the alloyed layers were examined by means of SEM-microscopy and an EDX analyser. The changes of electrical resistivity after laser alloying were measured in a temperature range of 77-450 K. It has been shown that the formation of alloyed lasers for metals with limited solubility (Ag-Sn), insoluable (Mo-Au, Cu-Cr), and even immiscible metals (Ni-Au, Ag-Ni) is possible. It is also possible to obtain alloyed layers with non-metallic additions (oxide). The investigations have shown how alloyed layers with strongly modified properites, especially electrical resistivity, can be obtained by means of different laser beams and various methods for the supplying of alloying elements.

  12. 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.

  13. Development of advanced material composites for use as internal insulation for LH2 tanks (gas layer concept)

    Science.gov (United States)

    Gille, J. P.

    1972-01-01

    A program is described that was conducted to develop an internal insulation system for potential application to the liquid hydrogen tanks of a reusable booster, where the tanks would be subjected to repeated high temperatures. The design of the internal insulation is based on a unique gas layer concept, in which capillary or surface tension effects are used to maintain a stable gas layer, within a cellular core structure, between the tank wall and the contained liquid hydrogen. Specific objectives were to select materials for insulation systems that would be compatible with wall temperatures of 350 F and 650 F during reentry into the earth's atmosphere, and to fabricate and test insulation systems under conditions simulating the operating environment. A materials test program was conducted to evaluate the properties of candidate materials at elevated temperatures and at the temperature of liquid hydrogen, and to determine the compatibility of the materials with a hydrogen atmosphere at the appropriate elevated temperature. The materials that were finally selected included Kapton polyimide films, silicone adhesives, fiber glass batting, and in the case of the 350 F system, Teflon film.

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

    OpenAIRE

    Vascon, Alessio

    2013-01-01

    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 p...

  15. Investigation of the effect of a buffer layer on the magnetic properties of soft materials

    OpenAIRE

    Sina, Soltanmohammad

    2013-01-01

    In this thesis, we study the influence of a buffer layer (Ta, Cr, W, Ti) on the structure formation, crystallographic orientation, resistivity and magnetic properties of NiFe alloy in the form of bilayer and multilayer nanostructures. In addition, we also investigate how these physical properties are affected by the buffer layer thickness (from 50 nm to 200 nm), the sputtering gas pressure and the applied magnetic field during deposition. All nanostructures were prepared by spu...

  16. MODELLING OF ACOUSTIC EMISSION SOURCE AND WAVE RESPONSE IN LAYERED MATERIALS

    Directory of Open Access Journals (Sweden)

    Alamin A.

    2014-03-01

    Full Text Available This study proposes a model of wave propagation in layered media for the use in acoustic emission (AE studies. This model aims to find an AE response at a free surface to the propagating waves originating at a dislocation source either in one layer medium or a layer-to-layer interface. Each of the layered media is assumed to be homogenous, linear elastic and isotropic. An integral transformation method has been applied to determine the wave response in frequency-wave number domain, which is then converted to time-space domain. In the numerical examples, we first select truncated values with the finite integral transformation, so that no wave interference happens in the responses from wave reflection at truncated boundaries. Next, we simulate wave propagation in an elastic half space, and compare results obtained with that from other kind bottom boundary. Next, we introduce a dis- location source in interface and compare a simulated AE wave response obtained with that computed in the layered medium to demonstrate the performance of the model. In each simulation, the results show good agreement with the reference solutions.

  17. Submicrometer-sized hierarchical hollow spheres of heavy lanthanide orthovanadates: sacrificial template synthesis, formation mechanism, and luminescent properties.

    Science.gov (United States)

    Yang, Xiaoyan; Xu, Lin; Zhai, Zheng; Cheng, Fangfang; Yan, Zhenzhen; Feng, Xiaomiao; Zhu, Junjie; Hou, Wenhua

    2013-12-23

    Hollow spheres of heavy lanthanide orthovanadates (LnVO4, Ln = Tb, Dy, Er, Tm, Yb, Lu) and yolk-shell structures of Ho(OH)CO3@HoVO4 have been successfully prepared by employing Ln(OH)CO3 colloidal spheres as a sacrificial template and NH4VO3 as a vanadium source. In particular, the as-obtained LuVO4 hollow spheres are assembled from numerous hollow-structured elliptic nanoparticles, and their textural parameters such as the inner and outer diameters, shell thicknesses, and number of shells could be finely tuned through introducing different amounts of NH4VO3 and employing Lu(OH)CO3 templates with different sizes. The possible mechanisms for the formation of hollow spheres and yolk-shell structures, and also the hollow-structured elliptic nanoparticles of LuVO4, i.e., building blocks of LuVO4 hollow spheres, are proposed and discussed in detail. Under ultraviolet excitation, the obtained LuVO4:Eu(3+) hollow spheres show strong red emissions located in the saturated color region, and the modulation of emission intensity and color purity could be realized by tuning the textural parameters of the obtained hollow spheres. It was found that the nanostructure of the building blocks of LuVO4:Eu(3+) hollow spheres also had an effect on the luminescent properties of the as-obtained materials. Moreover, the quantum efficiency could be affected by the textural parameters of the as-obtained LuVO4:Eu(3+) hollow spheres, and the double-shelled LuVO4:Eu(3+) hollow sphere has the highest quantum efficiency. In addition, the excellent biocompatibility indicates the potential biological applications of LuVO4 hollow spheres. PMID:24308367

  18. 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)

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

    Directory of Open Access Journals (Sweden)

    Fumio Uchikoba

    2012-07-01

    Full Text Available 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 ceramic material inside the same green sheet is possible. In this process, the arbitrary shape of the through pattern is formed in the green sheet of the base material by making use of photo resist films as sacrifice patterns, and then the base material is masked by the patterned photo resist film. After filling the slurry of the different material into the through pattern of the base material passing the resist mask, the pattern of the different ceramic material in the green sheet is achieved. In the present paper, the ferrite magnetic material and the alumina-glass composite material are used. The patterned structure inside the green sheet is obtained. The slurry preparation, the thickness of the mask resist film, and the obtained structure of the green sheet are discussed.

  20. 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

  1. Analytic expressions for atomic layer deposition: Coverage, throughput, and materials utilization in cross-flow, particle coating, and spatial atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yanguas-Gil, Angel; Elam, Jeffrey W., E-mail: jelam@anl.gov [Argonne National Laboratory, Energy Systems Division, 9700 S Cass Ave, Lemont, Illinois 60439 (United States)

    2014-05-15

    In this work, the authors present analytic models for atomic layer deposition (ALD) in three common experimental configurations: cross-flow, particle coating, and spatial ALD. These models, based on the plug-flow and well-mixed approximations, allow us to determine the minimum dose times and materials utilization for all three configurations. A comparison between the three models shows that throughput and precursor utilization can each be expressed by universal equations, in which the particularity of the experimental system is contained in a single parameter related to the residence time of the precursor in the reactor. For the case of cross-flow reactors, the authors show how simple analytic expressions for the reactor saturation profiles agree well with experimental results. Consequently, the analytic model can be used to extract information about the ALD surface chemistry (e.g., the reaction probability) by comparing the analytic and experimental saturation profiles, providing a useful tool for characterizing new and existing ALD processes.

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

    Energy Technology Data Exchange (ETDEWEB)

    Manvatkar, V.; De, A.; DebRoy, T. [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-09-28

    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.

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

    Science.gov (United States)

    Manvatkar, V.; De, A.; DebRoy, T.

    2014-09-01

    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.

  4. 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.

  5. Time resolved deformation of a thin polyimide film absorbing layer for laser-induced forward transfer printing

    Science.gov (United States)

    Brown, Matthew

    2010-03-01

    Laser-induced forward transfer (LIFT) is a versatile direct write technique capable of printing high resolution patterns from a variety of functional materials. In LIFT, the material to be printed is coated as a thin liquid or solid donor film onto the bottom surface of a glass substrate and held in close proximity above a receiver substrate. A pulsed laser is focused through the glass, into the donor film, initiating the transfer of a small amount of material onto the receiver. In order to shield sensitive donor materials from direct laser irradiation, sacrificial absorbing layers are often deposited before the donor is coated. Recently, we demonstrated the use of a thin polyimide film absorbing layer to provide damage free transfers of sensitive rheological donor materials. Transfer is initiated by the laser-induced formation of a rapidly expanding, sealed blister on the polyimide film which mechanically ejects the adjacent donor material without significant heating or contamination. In this talk, we present time resolved images of the blister deformation as well as the dynamics of an ejected liquid donor material.

  6. Can sacrificial feeding areas protect aquatic plants from herbivore grazing? Using behavioural ecology to inform wildlife management.

    Science.gov (United States)

    Wood, Kevin A; Stillman, Richard A; Daunt, Francis; O'Hare, Matthew T

    2014-01-01

    Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing damage by mute swans (Cygnus olor) to adjacent river vegetation of high conservation and economic value. The accuracy of model predictions was assessed by a comparison with observed field data, whilst prediction robustness was evaluated using a sensitivity analysis. We used repeated simulations to evaluate how the efficacy of the sacrificial feeding area was regulated by (i) food quantity, (ii) food quality, and (iii) the functional response of the forager. Our model gave accurate predictions of aquatic plant biomass, carrying capacity, swan mortality, swan foraging effort, and river use. Our model predicted that increased sacrificial feeding area food quantity and quality would prevent the depletion of aquatic plant biomass by swans. When the functional response for vegetation in the sacrificial feeding area was increased, the food quantity and quality in the sacrificial feeding area required to protect adjacent aquatic plants were reduced. Our study demonstrates how the insights of behavioural ecology can be used to inform wildlife management. The principles that underpin our model predictions are likely to be valid across a range of different resource-consumer interactions, emphasising the generality of our approach to the evaluation of strategies for resolving wildlife management problems. PMID:25077615

  7. A study of Al-Zn-Sn alloy sacrificial anode cathodic protection requirements for structure used in seawater

    International Nuclear Information System (INIS)

    Full text: The study will be focused on the alloying of Aluminum alloy sacrificial anode. The work will explore, evaluate and assess the effectiveness of Al-Zn-Sn alloy sacrificial anode tested in tropical seawater. This study is directed toward the development of new and more comprehensive data that will provide a technical basis for improved, more cost - effective guidelines for prediction, verification and optimization of cathodic protection requirements for structures used in tropical seawater. Furthermore, this study will also evaluate the potential and benefits of laboratory research upon marine corrosion without needed to be in the actual marine environment. The influence of alloy composition on the electrochemical properties of this Al-Zn-Sn will be determined by various tasks of testing which fully conducted in the laboratory. SEM and EDAX analysis will be employed in order to characterize surface structure of Al-Zn-Sn alloy. The corrosion measurement analyzer will be used by means to identify the electrochemical properties such as potential, corrosion rate and passivation of Al-Zn-Sn sacrificial anode when immersed in seawater. The relationship between morphological structure and electrochemical results will be examined. The data obtained will be used to evaluate the performance of Al-Zn-Sn alloy as a sacrificial anode cathodic protection for structure used in tropical seawater. Further verification will be made to testify that the Al-Zn-Sn alloy meets the qestify that the Al-Zn-Sn alloy meets the quality requirements to be used as a sacrificial anode in tropical seawater. (author)

  8. Sacrificial adsorbate for surfactants utilized in chemical floods of enhanced oil recovery operations

    Science.gov (United States)

    Johnson, Jr., James S. (Oak Ridge, TN); Westmoreland, Clyde G. (Rockwood, TN)

    1982-01-01

    The present invention is directed to a sacrificial or competitive adsorbate for surfactants contained in chemical flooding emulsions for enhanced oil recovery operations. The adsorbate to be utilized in the method of the present invention is a caustic effluent from the bleach stage or the weak black liquor from the digesters and pulp washers of the kraft pulping process. This effluent or weak black liquor is injected into an oil-bearing subterranean earth formation prior to or concurrent with the chemical flood emulsion and is adsorbed on the active mineral surfaces of the formation matrix so as to effectively reduce adsorption of surfactant in the chemical flood. Alternatively, the effluent or liquor can be injected into the subterranean earth formation subsequent to a chemical flood to displace the surfactant from the mineral surfaces for the recovery thereof.

  9. Zinc sacrificial anode behavior at elevated temperatures in sodium chloride and tap water environments

    International Nuclear Information System (INIS)

    Zinc sacrificial anode coupled to mild steel was tested in sodium chloride and tap water environments at elevated temperatures. The anode failed to protect the mild steel specimens in tap water environment at all temperatures specified for this study. This was partly due to the high resistivity of the medium. The temperature factor did not help to activate the anode in water tap medium. In sodium chloride environment the anode demonstrated good protection for steel cathodes. In tap water environment the anode weight loss was negligible. The zinc anode suffered intergranular corrosion in sodium chloride environment and this was noticed starting at 40 degree centigrade. In tap water environment the zinc anode demonstrated interesting behavior beyond 60 degree centigrade, that could be attributed to the phenomenon of reversal of potential at elevated temperatures. It also showed shallow pitting spots in tap water environment without any sign of intergranular corrosion. Zinc anodes would suffer intergranular corrosion at high temperatures. (author)

  10. Aluminum alloy for cladding excellent in sacrificial anode property and erosion-corrosion resistance

    International Nuclear Information System (INIS)

    An aluminum alloy for cladding excellent in sacrificial anode property and erosion-corrosion resistance, which consists essentially of, in weight percentage: zinc - 0.3 to 3.0%, magnesium - 0.2 to 4.0%, manganese - 0.3 to 2.0%, and, the balance aluminum and incidental impurities; said alloy including an aluminum alloy also containing at least one element selected from the group consisting of, in weight percentage: indium - 0.005 to 0.2%, tin - 0.01 to 0.3%, and, bismuth - 0.01 to 0.3%; provided that the total content of indium, tin and bismuth being up to 0.3%

  11. 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

  12. 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.

  13. Fabrication of tubed functionally graded material by slurry dipping process. Thickness control of dip-coated layer

    International Nuclear Information System (INIS)

    In order to obtain long life fuel cladding tubes for the fast breeder reactor, the concept of functionally graded material was applied for the material combination of Molybdenum/stainless steel/Titanium, in which Titanium and Molybdenum were placed at the inner and outer sides, respectively. Slurry dipping method was employed because of its capability of shape forming and microstructural control. We have hitherto reported the design criteria for the graded layers, preparation of the slurry, and microstructural control of the dip-coated layers. In the present report, the thickness control of the dip-coated layer is described in detail. The thickness of the dip-coated layer depends primarily on the viscosity of the slurry. Nevertheless, for the stable dispersion of the powder in the slurry, which dominates the microstructural homogeneity, an optimum viscosity value is present for the individual slurries. With stable slurries of Ti, Mo, stainless steel powders and their mixtures, the thicknesses of dip-coated layers were controlled in dependence of their viscosities and yield values. For Ti and stainless steel powders and their mixture a PAANa was used as a dispersing agent. A NaHMP was found to be effective for the dispersion of Mo powder and Mo/stainless steel powder mixture. For all slurries tested in the present investigation PVA addition was helpful for the viscosity control. Dip-coating maps have been drawn for the stabilization of the slurries and for the formation of films with a sufficient strength for further manipulation for the slurries with low viscosity (?10 mPa s). The final film thickness for the low-viscosity slurry with the optimum condition was about 200 ?m. The slurries with high viscosities of several hundreds mPa s had a good stability and the yield value was easy to be controlled. The film thickness was able to be adjusted in the size range between several tens and several hundreds ?m. The final thickness of the graded layer was determined on the basis of the material balance involved and densification ratio attained by drying, sintering and HIP treatment processes. (author)

  14. 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.

  15. 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

  16. 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…

  17. Effects of cyclical environments on high-performance multi-layer insulation materials.

    Science.gov (United States)

    Krause, D. R.; Fredrickson, G. O.; Klevatt, P. L.

    1971-01-01

    Results of a test program designed to determine the effects of 100 temperature and compressive loading cycles on several multilayer insulation materials and composites. A total of four reflector materials, four separator materials, eight face-sheet systems, and one fastener material were subjected to 100 temperature cycles from -320 to 400 or 650 F. Generic types of materials studied included Mylar, Kapton, Dacron, Nomex, and Beta Glass. The temperature cycling was followed by visual inspection, metal adhesion tests on the reflectors, and tensile tests of the face sheets, fastener, and separators. A total of six composites were subjected to compressive cycles between zero and 0.15 psi, and density changes were measured. Application of the experimental results to the shuttle orbiter is discussed.

  18. 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.

  19. 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

  20. Highly adhesive layered molybdenum oxide thin films prepared on a silicon substrate using suitable buffer materials

    International Nuclear Information System (INIS)

    MoO3 and organic/MoO3 hybrid thin films were prepared on a silicon substrate with an LaAlO3 or a CeO2 buffer layer. The MoO3 thin film, which was deposited by chemical vapor deposition, was soaked in an aqueous sodium hydrosulfite solution and aqueous butylammonium (BuNH3) solution to prepare (BuNH3) xMoO3 hybrid thin films. The high b-axis-oriented MoO3 grains was crucial in preventing the thin film from peeling off due to expansion of its interlayers during the intercalation process. Highly b-axis-oriented MoO3 grains can be deposited on the buffer layer at high temperatures, indicating that the film can work as a gas-sensing element

  1. Effect of nickel alloying layer on hydrogen absorption ability of Zr-Al getter material

    International Nuclear Information System (INIS)

    By using ion beam sputtering, an 85-Angstrom thick nickel layer was deposited on the Zr-Al alloy (non-evaporable getter) to improve the characteristic of the hydrogen absorption. The presputtering for 15 min to clean the surface passivation layer and the vacuum heating treatment of the sample at 750 degree C for 1 h for surface alloying can improve the ability of the gas absorption. The gas absorption experiments show fast absorption kinetics of the hydrogen pumping and good durability against contaminable gases. The Rutherford-back-scattering spectra and the secondary ion mass spectroscopy demonstrate the formation of an alloy of Zr, Al, and Ni in the near-surface area after the thermal process. The elastic recoil detection analysis indicates that the sample holds the original high capacity of hydrogen

  2. Deuterium retention in codeposited layers and carbon materials exposed to high flux D-plasma

    Science.gov (United States)

    Arkhipov, I. I.; Gorodetsky, A. E.; Zalavutdinov, R. Kh; Zakharov, A. P.; Burtseva, T. A.; Mazul, I. V.; Khripunov, B. I.; Shapkin, V. V.; Petrov, V. B.

    A ceramic BCN target with samples of dense RG-Ti-91 without boron, RG-Ti-B with boron (0.1 at.%) and porous POCO AXF-5Q graphites was exposed in a stationary D-plasma of the `Lenta' device with an ion energy of 200 eV and an ion flux of (3 - 6) × 10 17 D/cm 2s at 1040 and 1400 K to a fluence of ˜1 × 10 22 D/cm 2. Codeposited layers were obtained for comparison on the target surface. Thermal desorption spectroscopy (TDS) showed that the amount of deuterium in RG-Ti after exposure at 1040 K was more than an order of magnitude higher than in POCO (9 × 10 17 and 7 × 10 16 D/cm 2, respectively). The retention took place preferentially in a surface layer about 100 ?m thick. The bulk deuterium concentration in both RG-Ti and POCO was lower than 1 appm. The irradiated RG-Ti surface was subjected to strong erosion and consisted of `columnar' grains covered with TiC at their tips. The deuterium in RG-Ti irradiated at 1400 K was located in the surface layer (1.5 × 10 16 D/cm 2). The value of the bulk concentration did not exceed 0.1 appm while in POCO it was equal to about 20 appm. TDS for deuterium in RG-Ti demonstrated a spectrum similar to that for codeposited layers on a target surface. The differences in deuterium retention in the graphites are explained on the basis of structural differences. Considering tritium inventory assessment for ITER, dense graphites like RG-Ti are preferred for working divertor plates at high temperatures.

  3. Atomic layer deposition-based functionalization of materials for medical and environmental health applications

    OpenAIRE

    Narayan, Roger J.; Adiga, Shashishekar P; Pellin, Michael J.; Curtiss, Larry A; Hryn, Alexander J.; Stafslien, Shane; Chisholm, Bret; Shih, Chun-Che; Shih, Chun-Ming; Lin, Shing-Jong; Su, Yea-Yang; Jin, Chunming; Zhang, Junping; Monteiro-Riviere, Nancy A; Elam, Jeffrey W.

    2010-01-01

    Nanoporous alumina membranes exhibit high pore densities, well-controlled and uniform pore sizes, as well as straight pores. Owing to these unusual properties, nanoporous alumina membranes are currently being considered for use in implantable sensor membranes and water purification membranes. Atomic layer deposition is a thin-film growth process that may be used to modify the pore size in a nanoporous alumina membrane while retaining a narrow pore distribution. In addition, films deposited by...

  4. 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.

  5. 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...

  6. 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.

  7. 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)

  8. Triple-conducting layered perovskites as cathode materials for proton-conducting solid oxide fuel cells.

    Science.gov (United States)

    Kim, Junyoung; Sengodan, Sivaprakash; Kwon, Goeun; Ding, Dong; Shin, Jeeyoung; Liu, Meilin; Kim, Guntae

    2014-10-01

    We report on an excellent anode-supported H(+) -SOFC material system using a triple conducting (H(+) /O(2-) /e(-) ) oxide (TCO) as a cathode material for H(+) -SOFCs. Generally, mixed ionic (O(2-) ) and electronic conductors (MIECs) have been selected as the cathode material of H(+) -SOFCs. In an H(+) -SOFC system, however, MIEC cathodes limit the electrochemically active sites to the interface between the proton conducting electrolyte and the cathode. New approaches to the tailoring of cathode materials for H(+) -SOFCs should therefore be considered. TCOs can effectively extend the electrochemically active sites from the interface between the cathode and the electrolyte to the entire surface of the cathode. The electrochemical performance of NBSCF/BZCYYb/BZCYYb-NiO shows excellent long term stability for 500 h at 1023 K with high power density of 1.61 W?cm(-2) . PMID:25146887

  9. Effects of lossy, layered filler particles on the bulk permittivity of a composite material

    International Nuclear Information System (INIS)

    The ability to control the frequency at which a dielectric material exhibits maximum loss (the relaxation frequency) is of interest in telecommunications and radar absorption. A theoretical investigation of the behaviour of the complex bulk permittivity of a composite material with coated, spheroidal filler particles is presented. In the model, the filler particles are replaced mathematically by electric multipole sources located at their centres (Harfield N 2000 J. Mater. Sci. 35 5809-16). It is shown how factors such as particle shape, orientation with respect to the applied electric field, thickness of coating and permittivity value of the individual phases influences the bulk permittivity of the composite material. For a composite with coated filler particles, one or two relaxation frequencies may be observed. Employing the theory of Pauly and Schwan (Hanai T 1968 Electrical properties of emulsions Emulsion Science ed P Sherman (London: Academic)), particular attention is paid to the way in which the relaxation frequencies are affected by the material parameters

  10. Air-coupled ultrasonic investigation of multi-layered composite materials.

    Science.gov (United States)

    Kazys, R; Demcenko, A; Zukauskas, E; Mazeika, L

    2006-12-22

    Air-coupled ultrasonics is fine alternative for the immersion testing technique. Usually a through transmission and a pitch-catch arrangement of ultrasonic transducers are used. The pitch-catch arrangement is very attractive for non-destructive testing and evaluation of materials, because it allows one-side access to the object. However, this technique has several disadvantages. It is sensitive to specularly reflected and edge waves. A spatial resolution depends on a distance between the transducers. A new method for detection and visualisation of inhomogeneities in composite materials using one-side access air-coupled ultrasonic measurement technique is described. Numerical predictions of Lamb wave interaction with a defect in a composite material are carried out and the interaction mechanism is explained. Experimental measurements are carried out with different arrangements of the transducers. The proposed method enables detect delamination and impact type defects in honeycomb materials. PMID:16797664

  11. Layer-by-layer self-assembled multilayer films composed of graphene/polyaniline bilayers: high-energy electrode materials for supercapacitors.

    Science.gov (United States)

    Sarker, Ashis K; Hong, Jong-Dal

    2012-08-28

    Multilayer assemblies of uniform ultrathin film electrodes with good electrical conductivity and very large surface areas were prepared for use as electrochemical capacitors. A layer-by-layer self-assembly approach was employed in an effort to improve the processability of highly conducting polyaniline (PANi) and chemically modified graphene. The electrochemical properties of the multilayer film (MF-) electrodes, including the sheet resistance, volumetric capacitance, and charge/discharge ratio, were determined by the morphological modification and the method used to reduce the graphene oxide (GO) to reduced graphene oxide (RGO) in the multilayer films. The PANi and GO concentrations could be modulated to control the morphology of the GO monolayer film in the multilayer assemblies. Optical ellipsometry was used to determine the thickness of the GO film in a single layer (1.32 nm), which agreed well with the literature value (~1.3 nm). Hydroiodic acid (HI), hydrazine, or pyrolysis were tested for the reduction of GO to RGO. HI was found to be the most efficient technique for reducing the GO to RGO in the multilayer assemblies while minimizing damage to the virgin state of the acid-doped PANi. Ultimately, the MF-electrode, which could be optimized by fine-tuning the nanostructure and selecting a suitable reduction method, exhibited an excellent volumetric capacitance, good cycling stability, and a rapid charge/discharge rate, which are required for supercapacitors. A MF-electrode composed of 15 PANi/RGO bilayers yielded a volumetric capacitance of 584 F/cm(3) at a current density of 3.0 A/cm(3). Although this value decreased exponentially as the current density increased, approaching a value of 170 F/cm(3) at 100 A/cm(3), this volumetric capacitance is one of the best yet reported for the other carbon-based materials. The intriguing features of the MF-electrodes composed of PANi/RGO multilayer films offer a new microdimensional design for high energy storage devices for use in small portable electronic devices. PMID:22866750

  12. A study on the formation of plastic deformation layer in the steam generator tube materials during fretting wear

    International Nuclear Information System (INIS)

    The wear test of steam generator (SG) tube materials against ferritic stainles steels has been performed to evaluate the wear mechanism in water environment. It is difficult to observe the wear particle layers that are frequently formed in air environment. So the wear rate of SG tube materials in water environment depends on the change of mechanical properties between contact surfaces during fretting test. From the result of the subsurface hardness test, Inconel 690 has high hardness value than Inconel 600 as close to surface and this means that energy must be consumed in the contact surface of Inconel 690 to plastically deform the same volume. Main cause of hardness variation is due to the difference of the stacking fault energy with the chromium content. Besides, the deviation of wear coefficient in the Work-rate model was explained by the change of friction coefficient during fretting wear

  13. Mesoscopic effective material parameters for thin layers modeled as single and double grids of interacting loaded wires

    CERN Document Server

    Ikonen, Pekka; Gonzalo, Ramon; Simovski, Constantin; Tretyakov, Sergei

    2007-01-01

    As an example of thin composite layers we consider single and double grids of periodically arranged interacting wires loaded with a certain distributed reactive impedance. Currents induced to the wires by a normally incident plane wave are rigorously calculated and the corresponding dipole moment densities are determined. Using this data and the averaged fields we assign mesoscopic material parameters for the proposed grid structures. These parameters depend on the number of grids, and measure the averaged induced polarizations. It is demonstrated that properly loaded double grids possess polarization response that over some frequency range can be described by assigning negative values for the mesoscopic parameters. Discussion is conducted on the physical meaningfulness to assign such material parameters for thin composite slabs. The results predicted by the proposed method for the double-grid structures are compared with the results obtained using the commonly adopted S-parameter retrieval procedure.

  14. 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

  15. Toward Nanoscale Material Applications: Colloidal Quantum Dot Memory And Multi-Layer Graphene Electronics And Optoelectronics

    Science.gov (United States)

    Olac-vaw, Roman

    In this dissertation, the analysis of a possible use of colloidal semiconductor quantum dots (QDs) in memory storage devices is presented. The charging and discharging behaviors of capped cadmium selenide (CdSe) QDs deposited on a sheet of graphite film layers in ambient conditions were analyzed. Individual QDs can be addressed (charged) with the synergistic action of light and the mechanical interaction of a probe of an atomic force microscope (AFM). The probe squeezes the coating layer of QDs helping the photoelectron to tunnel to either the conductive AFM probe or to the substrate. The charge can be induced on individual QDs by locating the QDs with AFM. The charges were stable in ambient conditions (survived up to 24 hours), and even recovered within a minute after their forced neutralization by airflow of negative ions. The analyzed QDs allow recording information at a density up to 1Tb/cm 2. A possibility to attain charging (writing) time down to nanoseconds while keeping discharging (storage) times for more than 100 years is also demonstrated. These results may also be of interest for QDs based sensors, memory, and solar cell applications. Multi-layer heteroepitaxial graphene was successfully formed on 3C-SiC grown on a Si substrate using single gas source molecular beam epitaxy (MBE). The observation of ambipolar behavior, one of the unique properties of graphene, verifies the successful growth of graphene layers. The epitaxial graphene is believed to be unintentionally p-type doped with the Fermi level offset around +0.11˜+0.12 V at the Dirac point. Backgate field-effect transistors using multilayer graphene channel were designed, fabricated and characterized for electronic and optoelectronic applications. Even though some gate leakage current was observed, the experimental results show the device worked as an n-type transistor as well as an infrared detector. The drain saturated current of the graphene channel transistor is on the order of mA/mm. The extracted effective mobility was calculated to be around 6000 cm/ V.s which is much higher than Si under any circumstances. The photoreponsivity of the device was achieved up to 100 A/W at 1064 nm wavelength source. Constant photocurrent from 1400 nm to 1600 nm due to interband transition was also observed. The response at 1.6 THz with photoresponsivity of 75 muA/W at 1.6 THz is believed due to intraband transitions.

  16. 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...

  17. 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.

  18. 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 ?.

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

    International Nuclear Information System (INIS)

    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?1 for Cu2+, 1.67 mmol g?1 for Pb2+ and 1.00 mmol g?1 for Cd2+ at pH 7. • EPR spectroscopy reveals local coordination environment for Cu2+ 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?1). As a result, the material displays high metal uptake capacity for heavy metal ions such as Cu2+ (2.72 mmol g?1), Pb2+ (1.67 mmol g?1) and Cd2+ (1.00 mmol g?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 Cu2+ ions is rather homogeneous e.g. copper-binding phosphonate sites are arranged in average distances 5–8 ?

  20. Comparative researches concerning cleaning chosen construction materials surface layer using UV and IR laser radiation

    International Nuclear Information System (INIS)

    The paper presents comparative research studies of cleaning out of deposits and pollution disposals on different constructional materials like; steel, cast iron, aluminium, copper by using UV and IR laser radiation of wavelength ? =1.064 ?m; ? = 0.532 ?m; ? = 0.355 ?m and ? = 0.266 ?m and also impulse laser TEA CO2 at radiation ? = 10.6 ?m were used for the experiments. Achieved experimental results gave us basic information on parameters and conditions and application of each used radiation wavelength. Each kind of pollution and base material should be individually treated, selecting the length of wave and radiation energy density. Laser microtreatment allows for broad cleaning application of the surface of constructional materials as well as may be used in future during manufacturing processes as: preparation of surface for PVD technology, galvanotechnics, cleaning of the surface of machine parts etc. (author)

  1. Structuration of the low temperature co-fired ceramics (LTCC) using novel sacrificial graphite paste with PVA–propylene glycol–glycerol–water vehicle

    OpenAIRE

    Malecha, Karol; Maeder, Thomas; Jacq, Caroline; Ryser, Peter

    2011-01-01

    A novel formulation for thick-film graphite sacrificial pastes is studied in this paper. It is composed of coarse graphite powder (grain size: 25 ?m), dispersed in a vehicle consisting of polyvinyl alcohol (PVA) dissolved in a propylene glycol (PG)–glycerol (G)–water mix, which is not aggressive to thin LTCC sheets. The presented sacrificial paste has been successfully applied for fabrication of thin (

  2. 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.)

  3. 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.

    2015-05-01

    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.

  4. 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

  5. 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.

  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

    Science.gov (United States)

    Tong, Xin; Wang, Hui; Wang, Gang; Wan, Lijuan; Ren, Zhaoyu; Bai, Jintao; Bai, Jinbo

    2011-05-01

    High quality graphene sheets are synthesized through efficient oxidation process followed by rapid thermal expansion and reduction by H 2. 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.

  7. Can sacrificial feeding areas protect aquatic plants from herbivore grazing?: using behavioural ecology to inform wildlife management

    OpenAIRE

    Wood, Kevin A.; Stillman, Richard A.; Daunt, Francis; O Hare, Matthew T.

    2014-01-01

    Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing da...

  8. 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 plate 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)

  9. Preparation of mesoporous carbon/polypyrrole composite materials and their supercapacitive properties

    Directory of Open Access Journals (Sweden)

    WU-JUN ZOU

    2011-08-01

    Full Text Available We synthesized mesoporous carbons/polypyrrole composites, using a chemical oxidative polymerization and calcium carbonate as a sacrificial template. N2 adsorption-desorption method, Fourier infrared spectroscopy, and transmission electron microscopy were used to characterize the structure and morphology of the composites. The measurement results indicated that as-synthesized carbon with the disordered mesoporous structure and a pore size of approximately 5 nm was uniformly coated by polypyrrole. The electrochemical behavior of the resulting composite was examined by cyclic voltammetry and cycle life measurements, and the obtained results showed that the specific capacitance of the resulting composite electrode was as high as 313 F g?1, nearly twice the capacitance of pure mesoporous carbon electrode (163 F g–1. This reveals that the electrochemical performance of these materials is governed by a combination of the electric double layer capacitance of mesoporous carbon and pseudocapacitance of polypyrrole.

  10. A Gaussian treatment for the friction issue of Lennard-Jones potential in layered materials: Application to friction between graphene, MoS2, and black phosphorus

    Science.gov (United States)

    Jiang, Jin-Wu; Park, Harold S.

    2015-03-01

    The Lennard-Jones potential is widely used to describe the interlayer interactions within layered materials like graphene. However, it is also widely known that this potential strongly underestimates the frictional properties for layered materials. Here, we propose to supplement the Lennard-Jones potential by a Gaussian-type potential, which enables more accurate calculations of the frictional properties of two-dimensional layered materials. Furthermore, the Gaussian potential is computationally simple as it introduces only one additional potential parameter that is determined by the interlayer shear mode in the layered structure. The resulting Lennard-Jones-Gaussian potential is applied to compute the interlayer cohesive energy and frictional energy for graphene, MoS2, black phosphorus, and their heterostructures.

  11. Toughness and subcritical crack growth in Nb/Nb3Al layered materials

    International Nuclear Information System (INIS)

    A brittle intermetallic, Nb3Al, reinforced with a ductile metal, Nb, has been used to investigate the resistance curve and cyclic fatigue behavior of a relatively coarse laminated composite. With this system, the toughness of Nb3Al was found to increase from ?1 MPa?m to well over 20 MPa?m after several millimeters of stable crack growth; this was attributed to extensive crack bridging and plastic deformation within the Nb layers in the crack wake. Cyclic fatigue-crack growth resistance was also improved in the laminate microstructures compared to pure Nb3Al and Nb-particulate reinforced Nb3Al composites with crack arrester orientations in the laminate providing better fatigue resistance than either the matrix or pure Nb

  12. Desiccated Coconut Residue Based Activated Carbon as an Electrode Material for Electric Double Layer Capacitor

    Directory of Open Access Journals (Sweden)

    Mohd Adib Yahya

    2015-01-01

    Full Text Available Activated carbon derived from desiccated coconut residue was treated with sodium hydroxide (NaOH and analyzed for its supercapacitor performance. The sample was then characterized by N2 adsorption at -196°C, Energy dispersive x-ray (EDX analysis and X-ray diffraction (XRD in order to investigate its surface area, porosity and microcrystalline properties. Specific surface area (SSA was found to be 1394.79 m2/g with high microporosity of 76.92 %. Electrochemical double-layer capacitance was studied by cyclic voltammetry with potential window of 1V. The presence of high microporosity properties affects the supercapacitor performance due to lack of accessibility of the electrolyte into the activated carbon pores. The calculated specific capacitance was found to be 42 F/g.

  13. New lead inorganic-organic hybrid microporous and layered materials: synthesis, properties, and crystal structures.

    Science.gov (United States)

    Mao, Jiang-Gao; Wang, Zhike; Clearfield, Abraham

    2002-11-18

    Two new lead(II) phosphonates, namely, Pb2[PMIDA]*1.5H2O (1) (H4PMIDA = H2O3PCH2N(CH2CO2H)2) and Pb(H2L) (2) (H4L = CH3N(CH2PO3H2)2), have been synthesized by hydrothermal reactions at 150 degrees C. Complex 1 crystallized in tetragonal P42/n with cell dimensions of a = 17.317(7) and c = 7.507(5) A and Z = 8. In complex 1, Pb(1) is 6-coordinated by chelation in a tetradentate fashion by a PMIDA ligand (3 O, 1 N) and two phosphonate oxygen atoms from neighboring Pb(PMIDA) units in a severely distorted octahedral geometry, whereas Pb(2) is 6-coordinated by 4 carboxylate and 2 phosphonate oxygen atoms also with a severely distorted octahedral environment. These two different types of Pb(II) ions are interconnected through bridging carboxylate and phosphonate groups, resulting in a 3D network with micropores, whose cavity is filled by lattice water molecules interlinked via hydrogen bonds. Each PMIDA ligand bridges with 8 Pb(II) ions (3 Pb(1) and 5 Pb(2)). Complex 2 is orthorhombic, P2(1)2(1)2(1), with a = 7.382(5), b = 7.440(6), and c = 30.75(2) A and Z = 8. The structure of 2 features a 2D double lead(II) phosphonate layer along the ab plane. Each lead(II) ion is 5-coordinated by five phosphonate oxygen atoms from four ligands in a distorted trigonal bipyramid geometry. These double layers are further interconnected via hydrogen bonds between the protonated and uncoordinated phosphonate oxygens along the c-axis. PMID:12425639

  14. 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.

  15. Photocatalytic NOx abatement: the role of the material supporting the TiO2 active layer.

    Science.gov (United States)

    Bianchi, Claudia L; Pirola, Carlo; Selli, Elena; Biella, Serena

    2012-04-15

    The importance of the choice of a suitable substrate as supporting material for photoactive TiO(2), either in the form of powders or thin films or in photoactive paints, is frequently disregarded. In this paper four different supports (stainless steel, sand-blasted stainless steel, Teflon and glass) are object of investigation. The final aim is to verify the presence of interactions between the photocatalyst (AEROXIDE(®) TiO(2) P25 by Evonik Degussa Corporation) and the support, directly involved in the photocatalytic activity in the NO(x) abatement. The characterization results have been correlated with the photoactivity of the different samples. In particular, a coating of about 6-9 ?m seems to allow a photocatalytic result free from any positive or negative interference with the supporting material, therefore giving reliable results about the photoactivity of the TiO(2) under investigation. PMID:22119301

  16. Thermal relaxation in magnetic multi-layer materials with mixed hysteretic behavior

    Science.gov (United States)

    Dimian, M.; Andrei, P.; Mehta, M.; Idubor, O. A.

    2015-05-01

    Thermal relaxation phenomena in mixed-type hysteretic systems are investigated by using recently developed mixed Preisach model and Monte Carlo technique. The anomalous hysteretic behavior observed in several heterogeneous materials, especially in nanoscale embedding, is also generating unconventional relaxation processes which may involve several steps before relaxing to the anhysteretic state. The medium-term relaxation behavior is studied under various noisy environments and applied magnetic fields, analyzing the influence of noise strength, noise bandwidth, and field values on the relaxation characteristics.

  17. Synthesis of layered-layered xLi2MnO3·(1-x)LiMO2 (M = Mn, Ni, Co) nanocomposite electrodes materials by mechanochemical process

    Science.gov (United States)

    Kim, Soo; Kim, Chunjoong; Noh, Jae-Kyo; Yu, Seungho; Kim, Su-Jin; Chang, Wonyoung; Choi, Won Chang; Chung, Kyung Yoon; Cho, Byung-Won

    2012-12-01

    A strategy of facile route to prepare the Li2MnO3-stabilized LiMO2 (M = Mn, Ni, Co) electrode materials, cathode materials for Lithium secondary batteries that can be operated at the high voltage greater than 4.5 V, is proposed using the method of mechanochemical process. Li2MnO3 was synthesized at 400 °C, followed by the mechanochemical process with LiMO2 to form nanocomposite with the layered-layered structure. Structures and morphologies of xLi2MnO3·(1-x)LiMO2 are investigated to confirm the layered-layered structural integration. Various mole ratios of our xLi2MnO3·(1-x)LiMO2 electrode materials exhibit a large discharge capacity about 200 mAh g-1 at the room temperature. The cycle performances and the specific discharge capacities are improved by the secondary heat treatment for the xLi2MnO3·(1-x)LiMO2 composite electrodes where x ? 0.5. Our experimental results suggest the mechanochemical process is an easy and effective tool to form the nanocomposite of two components with controlled composition, especially, for the layered-layered integrated structure of xLi2MnO3·(1-x)LiMO2 system.

  18. 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

  19. 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.

  20. Electrochemical treatment of Orange II dye solution-Use of aluminum sacrificial electrodes and floc characterization

    International Nuclear Information System (INIS)

    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/m2, 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.

  1. 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.

  2. High energy spinel-structured cathode stabilized by layered materials for advanced lithium-ion batteries

    Science.gov (United States)

    Lu, Jia; Chang, Ya-Lin; Song, Bohang; Xia, Hui; Yang, Jer-Ren; Lee, Kim Seng; Lu, Li

    2014-12-01

    Due to well-known Jahn-Teller distortion in spinel LiMn1.5Ni0.5O4, it can only be reversibly electrochemically cycled between 3 and 4.8 V with a limited reversible capacity of ?147 mAh g-1. This study intends to embed the layer-structured Li2MnO3 nanodomains into LiMn1.5Ni0.5O4 spinel matrix so that the Jahn-Teller distortion can be suppressed even when the average Mn oxidation state is below +3.5. A series of xLi2MnO3·(1 - x)LiMn1.5Ni0.5O4 where x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1 are synthesized by co-precipitation method. The composites with intermediate values of x = 0.1, 0.2, 0.3, 0.4 and 0.5 exhibit both spinel and layered structural domains in the particles and show greatly improved cycle stability than that of the pure spinel. Among them, 0.3Li2MnO3·0.7LiMn1.5Ni0.5O4 delivers the highest and almost constant capacity after a few conditional cycles and shows superior cycle stability. Ex-situ X-ray diffraction results indicate that no Jahn-Teller distortion occurs during the cycling of the 0.3Li2MnO3·0.7LiMn1.5Ni0.5O4 composite. Additionally, 0.3Li2MnO3·0.7LiMn1.5Ni0.5O4 possesses a high energy density of ?700 Wh kg-1, showing great promise for advanced high energy density lithium-ion batteries.

  3. 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 p 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)

  4. Carbon materials with quasi-graphene layers: The dielectric, percolation properties and the electronic transport mechanism

    International Nuclear Information System (INIS)

    We investigate the dielectric properties of multi-walled carbon nanotubes (MWCNTs) and graphite filling in SiO2 with the filling concentration of 2–20 wt.% in the frequency range of 102–107 Hz. MWCNTs and graphite have general electrical properties and percolation phenomena owing to their quasi-structure made up of graphene layers. Both permittivity ? and conductivity ? exhibit jumps around the percolation threshold. Variations of dielectric properties of the composites are in agreement with the percolation theory. All the percolation phenomena are determined by hopping and migrating electrons, which are attributed to the special electronic transport mechanism of the fillers in the composites. However, the twin-percolation phenomenon exists when the concentration of MWCNTs is between 5–10 wt.% and 15–20 wt.% in the MWCNTs/SiO2 composites, while in the graphite/SiO2 composites, there is only one percolation phenomenon in the graphite concentration of 10–15 wt.%. The unique twin-percolation phenomenon of MWCNTs/SiO2 is described and attributed to the electronic transfer mechanism, especially the network effect of MWCNTs in the composites. The network formation plays an essential role in determining the second percolation threshold of MWCNTs/SiO2

  5. Hydrogen Storage Materials Based on Single-Layer Aluminum Nitride Nanostructures

    International Nuclear Information System (INIS)

    Using the first-principles method based on density functional theory, we study the hydrogen storage properties of Li-doped single-layer aluminum nitride nanostructures (AlN). For the pristine AlN sheet, each Al atom adsorbs one H2 with an average binding energy of 0.14 eV/H2. The hydrogen blinding energies and storage capacities can be markedly increased by doping Li atoms onto the AlN sheet. The charge analysis shows that there are charges transferring from the Li atoms to the AlN sheet, thus the charged Li atoms can polarize hydrogen molecules and enhance the interaction between hydrogen molecules and the AlN sheet. In the fully loaded cases, the Li-doped AlN sheet can contain up to 8.25wt% of molecular hydrogen with an average binding energy of 0.20 eV/H2. (condensed matter: structure, mechanical and thermal properties)

  6. Tuning charge–discharge induced unit cell breathing in layer-structured cathode materials for lithium-ion batteries

    Science.gov (United States)

    Zhou, Yong-Ning; Ma, Jun; Hu, Enyuan; Yu, Xiqian; Gu, Lin; Nam, Kyung-Wan; Chen, Liquan; Wang, Zhaoxiang; Yang, Xiao-Qing

    2014-11-01

    For LiMO2 (M=Co, Ni, Mn) cathode materials, lattice parameters, a(b), contract during charge. Here we report such changes in opposite directions for lithium molybdenum trioxide (Li2MoO3). A ‘unit cell breathing’ mechanism is proposed based on crystal and electronic structural changes of transition metal oxides during charge-discharge. Metal–metal bonding is used to explain such ‘abnormal’ behaviour and a generalized hypothesis is developed. The expansion of the metal-metal bond becomes the controlling factor for a(b) evolution during charge, in contrast to the shrinking metal-oxygen bond as controlling factor in ‘normal’ materials. The cation mixing caused by migration of molybdenum ions at higher oxidation state provides the benefits of reducing the c expansion range in the early stage of charging and suppressing the structure collapse at high voltage charge. These results may open a new strategy for designing layered cathode materials for high energy density lithium-ion batteries.

  7. Layered double hydroxide/carbon nanotubes composite as a high performance anode material for Ni–Zn secondary batteries

    International Nuclear Information System (INIS)

    Nanostructured Zn–Al layered double hydroxide (LDH) and carbon nanotubes (CNTs) have been successfully assembled to form LDH/CNT composite by electrostatic force. The morphology and microstructure of LDH/CNT composites were investigated by transmission electron microscopy and X-ray diffractometer. The assembly mechanism of LDH with CNTs was also discussed. Furthermore, the unique three-dimensional composite thus prepared was used as a new anode material for Ni–Zn secondary batteries to enhance the cell performance for the first time. The electrochemical performances of LDH/CNT composite as anode active material for Ni–Zn cells were investigated by galvanostatic charge/discharge cycling and cyclic voltammogram. The obtained results clearly demonstrated that the LDH/CNT composite had superior cycle stability compared with the conventional ZnO and Zn–Al–LDH, and the discharge capacity could maintain 390 mAh g?1 after 200 cycling tests. At the same time, the LDH/CNT composite also exhibited lower charge plateau voltage and higher discharge plateau voltage, and the average utilization ratio of the anode could reach 95.6%. These results indicated that this kind of composite is a promising anode material for Ni/Zn cells. It exhibits a high capacity (?400 mAh g?1) and high cycling stability

  8. 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.

  9. 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...

  10. 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.

  11. 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.

  12. 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

  13. Characterization of oxide layers on nuclear structural materials by X-ray diffraction and electrochemical techniques

    International Nuclear Information System (INIS)

    To predict the behavior of structural metallic materials incorporated within the CANDU nuclear reactors, superficial oxide films were grown in a controlled manner using an autoclave to simulate the environmental conditions specific to the nuclear reactors. In order to establish the structural modifications of the oxide films, the X-ray diffraction (XRD) and electrochemical analysis were used. The analyses performed shown differences between the carbon steel samples and Incoloy 800 samples exposed under different conditions corresponding to secondary circuit in CANDU nuclear reactors. The oxide phases were identified and the thickness of the films were calculated. The agreement between results obtained by these methods was discussed in connection with the microstructure of the samples. (authors)

  14. Characterization of oxide layers on nuclear structural materials by X-ray diffraction and electrochemical techniques

    International Nuclear Information System (INIS)

    To predict the behavior of structural metallic materials into the CANDU nuclear reactor, the oxide films on the surface were grown in a controlled manner using an autoclave simulating the environment specific into the nuclear reactor. In order to establish the structural modifications of the oxide films, the X-ray diffraction (XRD) and electrochemical analysis were used. Analyzes performed shown difference between the carbon steel samples and Incoloy 800 samples exposed under different conditions corresponding to secondary circuit in CANDU nuclear reactor. The oxide phases were identified and the thicknesses of the films were calculated. The agreement between results obtained by these methods was discussed according to the microstructure of the samples. (authors)

  15. Carbon aerogels as electrode material for electrical double layer supercapacitors-Synthesis and properties

    International Nuclear Information System (INIS)

    This paper constitutes a description of technological research the aim of which was to design a symmetric supercapacitor dedicated for the system of quality of electrical energy improvement (supply interruption, voltage dip). The main task was to use the carbon aerogel technology as the efficient method for production of electrode material with desirable properties. Carbon aerogels were prepared by carbonization of resorcinol-formaldehyde (RF) polymer gels. RF-gels were synthesized by curing polycondensation and by the inverse emulsion polymerization of resorcinol with formaldehyde, followed by microwave drying. The morphostructural characteristics of the carbon aerogels were investigated by atomic force microscopy (AFM) and the N2 adsorption (BET method). The electrochemical properties were characterized by means of cycle voltammetry, galvanostatic charging/discharging, and self-discharge.

  16. 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. 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.

  17. Selective wet etching of AlInN layers for nitride-based MEMS and photonic device structures

    Science.gov (United States)

    Watson, Ian M.; Xiong, Chang; Gu, Erdan; Dawson, Martin D.; Rizzi, Francesco; Bejtka, Katarzyna; Edwards, Paul R.; Martin, Robert W.

    2008-04-01

    Processing of GaN-AlInN-GaN epitaxial trilayers into 3-dimensional microstructures, using a combination of vertical dry etching and lateral wet etching, is discussed. The AlInN layers were grown so as to have an InN mole fraction close to the value of 17% required for lattice matching with GaN. Inductively coupled plasma etching with chlorine-argon gas mixtures was used to define mesa features with near-vertical sidewalls. Refluxing aqueous solutions of nitric acid of 2 molar concentration allowed highly selective lateral etching of the AlInN interlayers exposed on the mesa sidewalls, providing a novel sacrificial layer technology for the III-nitride materials. Lateral etch rates of 0.14-0.21 ?m/hr were observed for 100-nm AlInN interlayers. Two distinct applications are discussed. In one example, lateral etching of an AlInN layer was used to expose the underside of epitaxial GaN disks for fabrication of planar microcavities. Here, retention of an optically smooth GaN (000 I) surface on the underside of the disks is critical. Microbridges with potential for development as sensors were also demonstrated, and the deformation of these structures provides a sensitive probe of the local strain state of the undercut GaN layer.

  18. Low-Thermal-Conductivity (MS)1+x(TiS2)2 (M = Pb, Bi, Sn) Misfit Layer Compounds for Bulk Thermoelectric Materials

    OpenAIRE

    Chunlei Wan; Yifeng Wang; Ning Wang; Kunihito Koumoto

    2010-01-01

    A series of (MS)1+x(TiS2)2 (M = Pb, Bi, Sn) misfit layer compounds are proposed as bulk thermoelectric materials. They are composed of alternating rock-salt-type MS layers and paired trigonal anti-prismatic TiS2 layers with a van der Waals gap. This naturally modulated structure shows low lattice thermal conductivity close to or even lower than the predicted minimum thermal conductivity. Measurement of sound velocities shows that the ultra-low thermal conductivity partially originates from th...

  19. 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%).

  20. Materials science and integration bases for fabrication of (BaxSr1-x)TiO3 thin film capacitors with layered Cu-based electrodes

    International Nuclear Information System (INIS)

    The synthesis and fundamental material properties of layered TiAl/Cu/Ta electrodes were investigated to achieve the integration of Cu electrodes with high-dielectric constant (?) oxide thin films for application to the fabrication of high-frequency devices. The Ta layer is an excellent diffusion barrier to inhibit deleterious Cu diffusion into the Si substrate, while the TiAl layer provides an excellent barrier against oxygen diffusion into the Cu layer to inhibit Cu oxidation during the growth of the high-? layer in an oxygen atmosphere. Polycrystalline (BaxSr1-x)TiO3 (BST) thin films were grown on the Cu-based bottom electrode by rf magnetron sputtering at temperatures in the range 400-600 deg. C in oxygen, to investigate the performance of BST/Cu-based capacitors. Characterization of the Cu-based layered structure using surface analytical methods showed that two amorphous oxide layers were formed on both sides of the TiAl barrier, such that the oxide layer on the free surface of the TiAl layer correlates with TiAlOx, while the oxide layer at the TiAl/Cu interface is an Al2O3-rich layer. This double amorphous barrier layer structure effectively prevents oxygen penetration towards the underlying Cu and Ta layers. The TiAlOx interfacial layer, which has a relatively low dielectric constant compared with BST, reduced the total capacitance of the BST thin film capacitors. In addition, the layin film capacitors. In addition, the layered electrode-oxide interface roughening observed during the growth of BST films at high temperature, due to copper grain growth, resulted in large dielectric loss on the fabricated BST capacitors. These problems were solved by growing the BST layer at 450 deg. C followed by a rapid thermal annealing at 700 deg. C. This process significantly reduced the thickness of the TiAlOx layer and interface roughness resulting in BST capacitors exhibiting properties suitable for the fabrication of high-performance high-frequency devices. In summary, relatively high dielectric constant (280), low dielectric loss (0.007), and low leakage current (-8 A/cm2 at 100 kV/cm) were achieved for BST thin film capacitors with Cu-based electrodes

  1. Investigation of electrochemical double-layer (ECDL) capacitors electrodes based on carbon nanotubes and activated carbon materials

    Science.gov (United States)

    Emmenegger, Ch.; Mauron, Ph.; Sudan, P.; Wenger, P.; Hermann, V.; Gallay, R.; Züttel, A.

    The carbon nanotubes (CNT) show promising electrochemical characteristics particularly for electrochemical energy storage. The electrochemical double-layer (ECDL) capacitor is a new type of capacitor with features intermediate between those of a battery and a conventional capacitor. ECDL capacitors have been made using various types of CNT and activated carbon (a-C) as electrode material. The specific capacitance per surface area of the electrodes depends on the thickness and the specific surface area of the active material. The CNT electrodes show a specific capacitance from 0.8 and 280 mF cm -2 and 8 to 16 F cm -3, respectively. Increasing the mass density also helps to increase the capacitance. Commercially available activated carbon (a-C) electrodes were also tested in order to study their specific capacitance as a function of their physical properties. The various a-C electrodes have specific capacitance per surface area ranging from 0.4 to 3.1 F cm -2 and an average specific capacitance per volume of 40 F cm -3 due to their larger mass density.

  2. Enhanced thermoelectric properties of selenium-deficient layered TiSe(2-x): a charge-density-wave material.

    Science.gov (United States)

    Bhatt, Ranu; Bhattacharya, Shovit; Basu, Ranita; Ahmad, Sajid; Chauhan, A K; Okram, G S; Bhatt, Pramod; Roy, Mainak; Navaneethan, M; Hayakawa, Y; Debnath, A K; Singh, Ajay; Aswal, D K; Gupta, S K

    2014-11-12

    In the present work, we report on the investigation of low-temperature (300-5 K) thermoelectric properties of hot-pressed TiSe2, a charge-density-wave (CDW) material. We demonstrate that, with increasing hot-pressing temperature, the density of TiSe2 increases and becomes nonstoichiometric owing to the loss of selenium. X-ray diffraction, scanning electron microscopy, and transimission electron microscopy results show that the material consists of a layered microstructure with several defects. Increasing the hot-press temperature in nonstoichiometric TiSe2 leads to a reduction of the resistivity and enhancement of the Seebeck coefficient in concomitent with suppression of CDW. Samples hot-pressed at 850 °C exhibited a minimum thermal conductivity (?) of 1.5 W/m·K at 300 K that, in turn, resulted in a figure-of-merit (ZT) value of 0.14. This value is higher by 6 orders of magnitude compared to 1.49 × 10(-7) obtained for cold-pressed samples annealed at 850 °C. The enhancement of ZT in hot-pressed samples is attributed to (i) a reduced thermal conductivity owing to enhanced phonon scattering and (ii) improved power factor (?(2)?). PMID:25318103

  3. Self-sacrificial behavior and its explanation in terms of Max Scheler's concept of spirit.

    Science.gov (United States)

    Alyushin, Alexey

    2014-12-01

    One of the key concepts of the German philosopher Max Scheler (1874-1928) is his concept of spirit. He understands spirit as one of several naturally functioning human mental agencies, such as consciousness, will, memory, etc. That is, he treats the mental agency of spirit in a scientific way and avoids any esoteric or religious connotations that this peculiar term may involve. The nature of human spirit, according to Scheler, is the ability to withstand and deliberately redirect biological imperatives and instinctive drives, up to the point of purposefully throwing away one's own life. The presence of spirit constitutes the essence of the human being that differentiates him qualitatively from all animals. In this article, I argue that it is human spirit that plays the determinative role in causing heroic and self-sacrificial behavior. I also argue that the individual human spirit experiences its inherent development, thus having several rather dissimilar stages and manifestations. I discuss the meaning that the term 'spirit' has in the English and the American philosophical and psychological traditions and the meaning of the corresponding term 'der Geist' in the German traditions. The specific English-language understanding of the term 'spirit', compared to its German counterpart 'der Geist', namely, less scientific and more religious and esoteric and metaphorical for the former, makes it alien and almost unusable in the English and American traditions. The linguistic difference leads to the misunderstanding of some very important ideas brought by the concept of spirit as introduced by Scheler. My purpose is to overcome this discrepancy and omission and to introduce the notion and the concept of spirit, in their scientific understanding, into the arsenal of modern English-language cognitive science, psychology, and philosophy in order to provide for the full explanatory force of the hitherto neglected concept of spirit. PMID:24929557

  4. 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.

  5. Micro/nano structural analysis of mixed-material deposition layer formed on the first walls of large helical device

    International Nuclear Information System (INIS)

    Nano-geological diagnosis has been applied to the deposition layer formed on the Si specimens installed at the first wall surface during 2007FY Large Helical Device (LHD) experiment. Cross-sectional views of the deposition layers with nanometer-resolution were successfully observed by using focused ion beam fabrication technique and transmission electron microscopy observations. On the specimen located close to the divertor plates, deposition layer with ?800 nm thick was observed, and it has very fine and stratified layer structures in nanometer-level. Thickness of each layer is so various from 5 to 100 nm, and majority of the composition elements such as Fe, Cr, Ni, O and C were continuously changed towards the depth direction from the top surface. Characteristics of each layer show the operational history in the LHD and the mechanism of dusts formation by flaking of the layer. This work provides the completely new knowledge about the deposition layer in fusion devices.

  6. Materials

    Science.gov (United States)

    Glaessgen, Edward H.; Schoeppner, Gregory A.

    2006-01-01

    NASA Langley Research Center has successfully developed an electron beam freeform fabrication (EBF3) process, a rapid metal deposition process that works efficiently with a variety of weldable alloys. The EBF3 process can be used to build a complex, unitized part in a layer-additive fashion, although the more immediate payoff is for use as a manufacturing process for adding details to components fabricated from simplified castings and forgings or plate products. The EBF3 process produces structural metallic parts with strengths comparable to that of wrought product forms and has been demonstrated on aluminum, titanium, and nickel-based alloys to date. The EBF3 process introduces metal wire feedstock into a molten pool that is created and sustained using a focused electron beam in a vacuum environment. Operation in a vacuum ensures a clean process environment and eliminates the need for a consumable shield gas. Advanced metal manufacturing methods such as EBF3 are being explored for fabrication and repair of aerospace structures, offering potential for improvements in cost, weight, and performance to enhance mission success for aircraft, launch vehicles, and spacecraft. Near-term applications of the EBF3 process are most likely to be implemented for cost reduction and lead time reduction through addition of details onto simplified preforms (casting or forging). This is particularly attractive for components with protruding details that would require a significantly large volume of material to be machined away from an oversized forging, offering significant reductions to the buy-to-fly ratio. Future far-term applications promise improved structural efficiency through reduced weight and improved performance by exploiting the layer-additive nature of the EBF3 process to fabricate tailored unitized structures with functionally graded microstructures and compositions.

  7. Impact of carbon and tungsten as divertor materials on the scrape-off layer conditions in JET

    International Nuclear Information System (INIS)

    The impact of carbon and beryllium/tungsten as plasma-facing components on plasma radiation, divertor power and particle fluxes, and plasma and neutral conditions in the divertors has been assessed in JET both experimentally and by edge fluid code simulations for plasmas in low-confinement mode. In high-recycling conditions the studies show a 30% reduction in total radiation in the scrape-off (SOL) layer when replacing carbon (JET-C) with beryllium in the main chamber and tungsten in the divertor (JET-ILW). Correspondingly, at the low-field side (LFS) divertor plate a two-fold increase in power conducted to the plate and a two-fold increase in electron temperature at the strike point were measured. In low-recycling conditions the SOL was found to be nearly identical for both materials' configurations. Saturation and rollover of the ion currents to both low- and high-field side (HFS) plates was measured to occur at 30% higher upstream densities and radiated power fraction in JET-ILW. Past saturation, it was possible to reduce the ion currents to the LFS targets by a factor of 2 and to continue operating in stable, detached conditions in JET-ILW; in JET-C the reduction was limited to 50%. These observations are in qualitative agreement with predictions from the fluid edge code package EDGE2D/EIRENE, for which a 30% reduction of the total radiated power is also yielded when switching from C to Be/W. For matching upstream parameters the magnitude of predicted radiation isrs the magnitude of predicted radiation is, however, 50% to 100% lower than measured, independent of the materials' configuration. Inclusion of deuterium molecules and molecular ions, and temperature and density dependent rates in EIRENE reproduced the experimentally observed rollover of the ion current to the LFS plate, via reducing the electron temperature at the plate. (paper)

  8. 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

  9. Low-Thermal-Conductivity (MS1+x(TiS22 (M = Pb, Bi, Sn Misfit Layer Compounds for Bulk Thermoelectric Materials

    Directory of Open Access Journals (Sweden)

    Chunlei Wan

    2010-04-01

    Full Text Available A series of (MS1+x(TiS22 (M = Pb, Bi, Sn misfit layer compounds are proposed as bulk thermoelectric materials. They are composed of alternating rock-salt-type MS layers and paired trigonal anti-prismatic TiS2 layers with a van der Waals gap. This naturally modulated structure shows low lattice thermal conductivity close to or even lower than the predicted minimum thermal conductivity. Measurement of sound velocities shows that the ultra-low thermal conductivity partially originates from the softening of the transverse modes of lattice wave due to weak interlayer bonding. Combined with a high power factor, the misfit layer compounds show a relatively high ZT value of 0.28~0.37 at 700 K.

  10. Nano-electro-mechanical-systems (NEMS) and energy-efficient electronics and the emergence of two-dimensional layered materials beyond graphene

    Science.gov (United States)

    Kaul, Anupama B.

    2013-05-01

    Carbon-based nanomaterials such as graphene, a layered two-dimensional (2D) crystal, carbon nanotubes and carbon nanofibers have been explored extensively by researchers as well as the semiconductor industry as viable alternatives to silicon-based complimentary metal-oxide semiconductor transistors. Besides nanoscale transistors, the exceptional properties of carbon-based nanomaterials has stirred intense interest in considering these materials for applications ranging from interconnects, field-emission displays, photo-voltaics and nano-electro-mechanical-systems (NEMS). Recently, the emergence of other layered 2D crystals where the bonding between layers is held together by the weak van der Waals interaction, has opened up new avenues of research and exploration. Such material systems display a diverse array of properties ranging from insulating hexagonal-BN, metallic NbS2 to semiconducting MoS2. The ability to engineer the materials properties in these 2D layered materials provides promising prospects for their use in a wide variety of applications ranging from electronics, photonics, sensing, energy harvesting, flexible electronics and related applications over the coming years.

  11. A novel technique for time-resolved detection and tracking of interfacial and matrix fracture in layered materials

    Science.gov (United States)

    Minnaar, Karel; Zhou, Min

    2004-12-01

    A novel experimental technique is developed for time-resolved detection and tracking of damage in the forms of delamination and matrix cracking in layered materials such as composite laminates. The technique is non-contact in nature and uses dual or quadruple laser interferometers for high temporal resolution. Simultaneous measurements of differential displacement and velocity at individual locations are obtained to analyze the initiation and progression of interfacial fracture and/or matrix cracking/delamination in a polymer matrix composite laminate system reinforced by graphite fibers. The measurements at multiple locations allow the speeds at which interfacial crack front (mode-I) or matrix cracking/delamination front (mode-II dominated) propagates to be determined. Experiments carried out use three-point bend configurations. Impact loading is achieved using a modified Kolsky bar apparatus with a complete set of diagnostics for load, deformation, deformation rate, and input energy measurement. This technique is used to characterize the full process of damage initiation and growth. The experiments also focused on the quantification of the speed at which delamination or damage propagates under primarily mode-I and mode-II conditions. The results show that the speed of delamination (mode-I) or the speed of matrix cracking/delamination (primarily mode-II) increases linearly with impact velocity. Furthermore, speeds of matrix failure/delamination under primarily mode-II conditions are much higher than the speeds of mode-I crack induced delamination under mode-I conditions.

  12. Material transport by erosion and redeposition on surface probes in the scrape-off layer of JET

    International Nuclear Information System (INIS)

    The material transport by erosion and redeposition at the plasma facing wall areas in high temperature plasma experiments has been studied using limiter-like carbon probes with well defined surface deposits and depth markers. The probes have been exposed in the scrape-off layer (SOL) of the Joint European Torus (JET) during single discharges. For the evaluation of these experiments a computer program, ERO, has been developed. The calculated erosion-deposition rates for carbon as a function of the distance to the last closed flux surface (LCFS) agree well with the experimental results. For a single 4He JET discharge, erosion yields of 530 A for the silicon deposit and 80 A for vanadium have been measured near the LCFS. A large amount of redeposited silicon (about 17% of the sputtered atoms) has been found on the probe surface in co-deposition with carbon on an area not favoured by the proposed model. This observation can be explained by an additional force on the impurity ions (e.g. the existence of a local electric field), which may cause the deposition. (author). 23 refs, 6 figs, 2 tabs

  13. Neighboring Hetero-Atom Assistance of Sacrificial Amines to Hydrogen Evolution Using Pt-Loaded TiO2-Photocatalyst

    Directory of Open Access Journals (Sweden)

    Masahide Yasuda

    2014-05-01

    Full Text Available Photocatalytic H2 evolution was examined using Pt-loaded TiO2-photocatalyst in the presence of amines as sacrificial agents. In the case of amines with all of the carbon attached to the hetero-atom such as 2-aminoethanol, 1,2-diamonoethane, 2-amino-1,3-propanediol, and 3-amino-1,2-propanediol, they were completely decomposed into CO2 and water to quantitatively evolve H2. On the other hand, the amines with both hetero-atoms and one methyl group at the ?-positions (neighboring carbons of amino group such as 2-amino-1-propanol and 1,2-diaminopropane were partially decomposed. Also, the photocatalytic H2 evolution using amines without the hetero-atoms at the ?-positions such as ethylamine, propylamine, 1-butylamine, 1,3-diaminopropane, 2-propylamine, and 2-butylamine was inefficient. Thus, it was found that the neighboring hetero-atom strongly assisted the degradation of sacrificial amines. Moreover, rate constants for H2 evolution were compared among amines. In conclusion, the neighboring hetero-atom did not affect the rate constants but enhanced the yield of hydrogen evolution.

  14. PtRu nanofilm formation by electrochemical atomic layer deposition (E-ALD).

    Science.gov (United States)

    Jayaraju, Nagarajan; Banga, Dhego; Thambidurai, Chandru; Liang, Xuehai; Kim, Youn-Guen; Stickney, John L

    2014-03-25

    The high CO tolerance of PtRu electrocatalysis, compared with pure Pt and other Pt-based alloys, makes it interesting as an anode material in proton exchange membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC). This report describes the formation of bimetallic PtRu nanofilms using the electrochemical form of atomic layer deposition (E-ALD). Metal nanofilm formation using E-ALD is facilitated by use of surface-limited redox replacement (SLRR), where an atomic layer (AL) of a sacrificial metal is first formed by UPD. The AL is then spontaneously exchanged for a more noble metal at the open-circuit potential (OCP). In the present study, PtRu nanofilms were formed using SLRR for Pt and Ru, and Pb UPD was used to form the sacrificial layers. The PtRu E-ALD cycle consisted of Pb UPD at -0.19 V, followed by replacement using Pt(IV) ions at OCP, rinsing with blank, then Pb UPD at -0.19 V, followed by replacement using Ru(III) ions at OCP. PtRu nanofilm thickness was controlled by the number of times the cycle was repeated. PtRu nanofilms with atomic proportions of 70/30, 82/18, and 50/50 Pt/Ru were formed on Au on glass slides using related E-ALD cycles. The charge for Pb UPD and changes in the OCP during replacement were monitored during the deposition process. The PtRu films were then characterized by CO adsorption and electrooxidation to determine their overpotentials. The 50/50 PtRu nanofilms displayed the lowest CO electrooxidation overpotentials as well as the highest currents, compared with the other alloy compositions, pure Pt, and pure Ru. In addition, CO electrooxidation studies of the terminating AL on the 50/50 PtRu nanostructured alloy were investigated by deposition of one or two SLRR of Pt, Ru, or PtRu on top. PMID:24568151

  15. Structural analysis and characterization of layer perovskite oxynitrides made from Dion-Jacobson oxide precursors

    International Nuclear Information System (INIS)

    A three-layer oxynitride Ruddlesden-Popper phase Rb1+xCa2Nb3O10-xNx.yH2O (x=0.7-0.8, y=0.4-0.6) was synthesized by ammonialysis at 800oC from the Dion-Jacobson phase RbCa2Nb3O10 in the presence of Rb2CO3. Incorporation of nitrogen into the layer perovskite structure was confirmed by XPS, combustion analysis, and MAS NMR. The water content was determined by thermal gravimetric analysis and the rubidium content by ICP-MS. A similar layered perovskite interconversion occurred in the two-layer Dion-Jacobson oxide RbLaNb2O7 to yield Rb1+xLaNb2O7-xNx.yH2O (x=0.7-0.8, y=0.5-1.0). Both compounds were air- and moisture-sensitive, with rapid loss of nitrogen by oxidation and hydrolysis reactions. The structure of the three-layer oxynitride Rb1.7Ca2Nb3O9.3N0.7.0.5H2O was solved in space group P4/mmm with a=3.887(3) and c=18.65(1)A, by Rietveld refinement of X-ray powder diffraction data. The two-layer oxynitride structure Rb1.8LaNb2O6.3N0.7.1.0H2O was also determined in space group P4/mmm with a=3.934(2) and c=14.697(2)A. GSAS refinement of synchrotron X-ray powder diffraction data showed that the water molecules were intercalated between a double layer owere intercalated between a double layer of Rb+ ions in both the two- and three-layer Ruddlesden-Popper structures. Optical band gaps were measured by diffuse reflectance UV-vis for both materials. An indirect band gap of 2.51eV and a direct band gap of 2.99eV were found for the three-layer compound, while an indirect band gap of 2.29eV and a direct band gap of 2.84eV were measured for the two-layer compound. Photocatalytic activity tests of the three-layer compound under 380nm pass filtered light with AgNO3 as a sacrificial electron acceptor gave a quantum yield of 0.025% for oxygen evolution

  16. Superwetting double-layer polyester materials for effective removal of both insoluble oils and soluble dyes in water.

    Science.gov (United States)

    Li, Bucheng; Wu, Lei; Li, Lingxiao; Seeger, Stefan; Zhang, Junping; Wang, Aiqin

    2014-07-23

    Inspired by the mussel adhesive protein and the lotus leaf, Ag-based double-layer polyester (DL-PET) textiles were fabricated for effective removal of organic pollutants in water. The DL-PET textiles are composed of a top superamphiphilic layer and a bottom superhydrophobic/superoleophilic layer. First, the PET textiles were modified with a layer of polydopamine (PDA) and deposited with Ag nanoparticles to form the PET@PDA@Ag textiles. The top superamphiphilic layer, formed by immobilizing Ag3PO4 nanoparticles on the PET@PDA@Ag textile, shows excellent visible-light photocatalytic activity. The bottom superhydrophobic/superoleophilic layer, formed by modifying the PET@PDA@Ag textile using dodecyl mercaptan, is mechanically, environmentally, and chemically very stable. The water-insoluble oils with low surface tension can penetrate both layers of the DL-PET textiles, while the water with soluble organic dyes can only selectively wet the top layer owing to their unique wettability. Consequently, the water-soluble organic contaminants in the collected water can be decomposed by the Ag3PO4 nanoparticles of the top layer under visible-light irradiation or even sunlight in room conditions. Thus, the DL-PET textiles can remove various kinds of organic pollutants in water including both insoluble oils and soluble dyes. The DL-PET textiles feature unique wettability, high oil/water separation efficiency, and visible-light photocatalytic activity. PMID:24956183

  17. Correction of the spectral lines of a laser plasma for measurement of the depth profile of layered materials in an ablation crater

    International Nuclear Information System (INIS)

    An algorithm for the correction of the atomic lines in the spectrum of a laser plasma was developed for determination of the depth profile of the elemental composition of layered materials in an ablation crater. The application of this algorithm made it possible to eliminate the profile smoothing effect as a consequence of a change in the line intensity as the crater becomes deeper. The correction of the profile is illustrated by an example of measurement of the thickness of a diffusion layer of zinc-plated sheet steel before and after its heating at 4520C. (interaction of laser radiation with matter. laser plasma)

  18. Tamm plasmon-polariton with negative group velocity induced by a negative index meta-material capping layer at metal-Bragg reflector interface.

    Science.gov (United States)

    Liu, Cunding; Kong, Mingdong; Li, Bincheng

    2014-05-01

    Influence of a negative refractive index meta-material (NIM) capping layer on properties of Tamm plasmon-polariton at the interface of metal-Bragg reflector structure is investigated. Conditions for excitation of the plasmon-polariton is determined from reflectivity mapping calculation and analyzed with cavity mode theory. For specific thicknesses of capping layers, Tamm plasmon-polariton with negative group velocity is revealed in a wide region of frequency. Different from backward optical propagation induced by negative effective-group-refractive-index in dispersive media, negative group velocity of Tamm plasmon-polariton results from opposite signs of cross-section-integrated field energy and Poynting vector. PMID:24921834

  19. Investigation of changes in the surface layer composition of materials exposed to sodium by glow discharge optical and Auger electron spectroscopy

    International Nuclear Information System (INIS)

    The paper describes the changes in the composition of surface layers of different materials caused by sodium corrosion and mass transfer. The concentration profiles of different metallic elements and of the nonmetallic elements carbon and boron in the diffusion zones are determined by glow discharge optical spectroscopy (GDOS). The composition of the outermost layers was analyzed by Auger electron spectroscopy (AES) combined with in situ ion milling. After a short description of these two methods of spectroscopy, their working ranges and their reliability are shown

  20. 2D Materials: The Influence of Water on the Optical Properties of Single-Layer Molybdenum Disulfide (Adv. Mater. 17/2015).

    Science.gov (United States)

    Varghese, Joseph O; Agbo, Peter; Sutherland, Alexander M; Brar, Victor W; Rossman, George R; Gray, Harry B; Heath, James R

    2015-05-01

    A scanning probe image of single-layer MoS2 trapping water on a mica surface is depicted on the left, with its corresponding photoluminescence image depicted on the right. The trapped water strongly quenches the fluorescence of single-layer MoS2 and distinctly affects its optical properties. The work by J. R. Heath and co-workers on page 2734 highlights the significance of the local chemical environment in determining the opto-electronic properties of 2D materials. PMID:25939793

  1. 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.

  2. Structural analysis and characterization of layer perovskite oxynitrides made from Dion Jacobson oxide precursors

    Science.gov (United States)

    Schottenfeld, Joshua A.; Benesi, Alan J.; Stephens, Peter W.; Chen, Gugang; Eklund, Peter C.; Mallouk, Thomas E.

    2005-07-01

    A three-layer oxynitride Ruddlesden-Popper phase Rb 1+xCa 2Nb 3O 10-xN x· yH 2O ( x=0.7-0.8, y=0.4-0.6) was synthesized by ammonialysis at 800 °C from the Dion-Jacobson phase RbCa 2Nb 3O 10 in the presence of Rb 2CO 3. Incorporation of nitrogen into the layer perovskite structure was confirmed by XPS, combustion analysis, and MAS NMR. The water content was determined by thermal gravimetric analysis and the rubidium content by ICP-MS. A similar layered perovskite interconversion occurred in the two-layer Dion-Jacobson oxide RbLaNb 2O 7 to yield Rb 1+xLaNb 2O 7-xN x· yH 2O ( x=0.7-0.8, y=0.5-1.0). Both compounds were air- and moisture-sensitive, with rapid loss of nitrogen by oxidation and hydrolysis reactions. The structure of the three-layer oxynitride Rb 1.7Ca 2Nb 3O 9.3N 0.7·0.5H 2O was solved in space group P4 /mmm with a=3.887(3) and c=18.65(1) Å, by Rietveld refinement of X-ray powder diffraction data. The two-layer oxynitride structure Rb 1.8LaNb 2O 6.3N 0.7·1.0H 2O was also determined in space group P4 /mmm with a=3.934(2) and c=14.697(2) Å. GSAS refinement of synchrotron X-ray powder diffraction data showed that the water molecules were intercalated between a double layer of Rb+ ions in both the two- and three-layer Ruddlesden-Popper structures. Optical band gaps were measured by diffuse reflectance UV-vis for both materials. An indirect band gap of 2.51 eV and a direct band gap of 2.99 eV were found for the three-layer compound, while an indirect band gap of 2.29 eV and a direct band gap of 2.84 eV were measured for the two-layer compound. Photocatalytic activity tests of the three-layer compound under 380 nm pass filtered light with AgNO 3 as a sacrificial electron acceptor gave a quantum yield of 0.025% for oxygen evolution.

  3. Enhanced charge collection with ultrathin AlOx electron blocking layer for hole-transporting material-free perovskite solar cell.

    Science.gov (United States)

    Wei, Huiyun; Shi, Jiangjian; Xu, Xin; Xiao, Junyan; Luo, Jianheng; Dong, Juan; Lv, Songtao; Zhu, Lifeng; Wu, Huijue; Li, Dongmei; Luo, Yanhong; Meng, Qingbo; Chen, Qiang

    2015-02-21

    An ultrathin AlOx layer has been deposited onto a CH3NH3PbI3 film using atomic layer deposition technology, to construct a metal-insulator-semiconductor (MIS) back contact for the hole-transporting material-free perovskite solar cell. By optimization of the ALD deposition cycles, the average power conversion efficiency (PCE) of the cell has been enhanced from 8.61% to 10.07% with a highest PCE of 11.10%. It is revealed that the improvement in cell performance with this MIS back contact is mainly attributed to the enhancement in charge collection resulting from the electron blocking effect of the AlOx layer. PMID:25594083

  4. Study of deuterium retention in/release from ITER-relevant Be-containing mixed material layers implanted at elevated temperatures

    International Nuclear Information System (INIS)

    D implantation into Be-containing mixed material layers: Be, Be–W (W: ?6 at.%) and Be–C (C: ?50 at.%), was performed at elevated temperatures. The temperature dependence of D retention varied depending on the admixed element. D retention in Be and Be–W layers decreases with increasing implantation temperature, while the Be–C layers maintained rather high D retention in the present investigated temperature range (up to 623 K). D desorption behaviour from Be–C suggests the contribution of C–D bonds to D retention. W admixture into Be can significantly suppress D retention in Be. Long-term isothermal annealing at 513 and 623 K for D removal was also performed to simulate the ITER-wall-baking scenario. Even extended annealing at temperatures comparable to or lower than the implantation temperature does not lead to a significant release of retained D

  5. Collision of a vortex ring on granular material. Part I. Interaction of the vortex ring with the granular layer

    International Nuclear Information System (INIS)

    An experimental study was carried out on the normal impact of the vortex ring on the granular layer. The Reynolds number of the vortex ring ranged from 1000 to 6000, whereas the distance to the granular layer (glass beads of diameter 0.10 mm) varied between 2 and 13 times of the diameter of the vortex ring generator nozzle. The velocity field was visualized by the sodium fluorescein and was measured by particle image velocimetry or particle tracking velocimetry. The flow field in the vicinity of the granular surface was also visualized by an almost mono-layer of fine particles deposited on the main granular layer, which elucidated the development of the secondary and tertiary vortex rings. Generally speaking, the characteristics of the granular layer are found to be similar to a liquid plane for the impact of a vortex ring of a smaller impulse, whereas it is closer to a solid plane for a vortex ring of a larger impulse. For the vortex ring with a much larger impulse, the granular layer is engraved, whose patterns reflect the deformation of the primary and/or secondary vortex ring due to the interaction with the granular layer (as will be described in part II). (paper)

  6. 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.

  7. Biodistance analysis of the Moche sacrificial victims from Huaca de la Luna plaza 3C: Matrix method test of their origins.

    Science.gov (United States)

    Sutter, Richard C; Verano, John W

    2007-02-01

    The purpose of this study is to test two competing models regarding the origins of Early Intermediate Period (AD 200-750) sacrificial victims from the Huacas de Moche site using the matrix correlation method. The first model posits the sacrificial victims represent local elites who lost competitions in ritual battles with one another, while the other model suggests the victims were nonlocal warriors captured during warfare with nearby polities. We estimate biodistances for sacrificial victims from Huaca de la Luna Plaza 3C (AD 300-550) with eight previously reported samples from the north coast of Peru using both the mean measure of divergence (MMD) and Mahalanobis' distance (d2). Hypothetical matrices are developed based upon the assumptions of each of the two competing models regarding the origins of Moche sacrificial victims. When the MMD matrix is compared to the two hypothetical matrices using a partial-Mantel test (Smouse et al.: Syst Zool 35 (1986) 627-632), the ritual combat model (i.e. local origins) has a low and nonsignificant correlation (r = 0.134, P = 0.163), while the nonlocal origins model is highly correlated and significant (r = 0.688, P = 0.001). Comparisons of the d2 results and the two hypothetical matrices also produced low and nonsignificant correlation for the ritual combat model (r = 0.210, P = 0.212), while producing a higher and statistically significant result with the nonlocal origins model (r = 0.676, P = 0.002). We suggest that the Moche sacrificial victims represent nonlocal warriors captured in territorial combat with nearby competing polities. PMID:17133431

  8. Modeling mixed clockwise and counter-clockwise hysteresis in multi-layer materials by using a generalized Jiles–Atherton model

    Energy Technology Data Exchange (ETDEWEB)

    Andrei, Petru, E-mail: pandrei@eng.fsu.edu [Department of Electrical and Computer Engineering, Florida State University and Florida A and M University, Tallahassee, FL 32310 (United States); Mehta, Mohit [Department of Electrical and Computer Engineering, Florida State University and Florida A and M University, Tallahassee, FL 32310 (United States); Dimian, Mihai [Faculty of Electrical Engineering and Computer Science, Stefan cel Mare University, Suceava 720229 (Romania)

    2014-02-15

    A generalized Jiles–Atherton model is proposed to describe mixed clockwise and counter-clockwise hysteresis loops. While it is physically inconsistent for homogeneous magnetic materials, this mixed type of hysteresis is exhibited by several multi-layer and superlattice materials with antiferromagnetic coupling. The modeling approach is based on a newly developed clockwise hysteretic model using the Jiles–Atherton framework and its linear superposition to the classical counter-clockwise version. The resulting technique is implemented in open-access academic software for hysteresis and simulation samples are presented in the paper.

  9. Critical Temperature Tc and Charging Energy Ec between B-B layers of Superconducting diboride materials MgB2 in 3D JJA model

    OpenAIRE

    Kawabata, C.; Hayashi, N.; Ono, F.

    2001-01-01

    The diboride materials MB2 (M = Mg, Be, Pb, etc.) are discussed on the basis of the 3D Josephson junction array (JJA) model due to Kawabata-Shenoy-Bishop, in terms of the B-B layers in the diborides analogous to the Cu-O ones in the cuprates. We propose a possibility of superconducting materials with the MgB2-type structure which exhibit higher critical temperature Tc over 39K of MgB2. We point out a role of interstitial ionic atoms (e.g., Mg in MgB2) as capacitors be...

  10. Modeling mixed clockwise and counter-clockwise hysteresis in multi-layer materials by using a generalized Jiles–Atherton model

    International Nuclear Information System (INIS)

    A generalized Jiles–Atherton model is proposed to describe mixed clockwise and counter-clockwise hysteresis loops. While it is physically inconsistent for homogeneous magnetic materials, this mixed type of hysteresis is exhibited by several multi-layer and superlattice materials with antiferromagnetic coupling. The modeling approach is based on a newly developed clockwise hysteretic model using the Jiles–Atherton framework and its linear superposition to the classical counter-clockwise version. The resulting technique is implemented in open-access academic software for hysteresis and simulation samples are presented in the paper

  11. The Hardness of Boride Layer on the S45C Iron (A preliminary study on surface hardening of ferrous material

    Directory of Open Access Journals (Sweden)

    Sutrisno

    2012-08-01

    Full Text Available The property such as microhardness of boride layer formed on S45C iron was investigated. Boronizing was carried out in a solid medium consisting of nano size powders of 50% B4C as a donor, 45% SiC as a diluent, and 5% KBF4 as an activator treated at the temperature of 10000C for 8 hours. The phases that were formed on the substrate was found as Fe2B and FeB layer that had smooth and flate shape morphology. The hardness of boride layer on S45C was over 2000 HV, while the hardness of untreated S45C iron was about 196,39 HV. Depending on process time and temperature, the depth of boride layer ranges from 25 to 55 µm, leading to a diffusion controlled process

  12. Layered Li-Mn-oxide with the O2 structure: A cathode material for Li-ion cells which does not convert to spinel

    International Nuclear Information System (INIS)

    Layered sodium manganese bronzes having the P2 structure (Na2/3[Li5/6]O2), were used to prepare layered lithium manganese oxides by ion exchange of Na by Li using LiBr in hexanol. X-ray diffraction and chemical analysis show that layered Li2/3[Li1/6Mn5/6]O2 has an O2 type structure. The arrangement of manganese and oxygen atoms in this phase differs fundamentally from that found in layered LiMnO2(O3 structure), in orthorhombic LiMnO2, and in spinel Li2Mn2O4 so that conversion to spinel during electrochemical cycling is not expected. Li2/3[Li1/6Mn5/6]O2 as well as the related Li2/3[Li1/18Mn17/18]O2 and Li2/3[Mn0.85Co0.15]O2 have a reversible charge capacity of about 150 mAh/g. During cycling the new cathode materials do not convert to spinel, in contrast to the behavior of layered and orthorhombic LiMnO2

  13. High-energy 'composite' layered manganese-rich cathode materials via controlling Li2MnO3 phase activation for lithium-ion batteries.

    Science.gov (United States)

    Yu, Haijun; Kim, Hyunjeong; Wang, Yarong; He, Ping; Asakura, Daisuke; Nakamura, Yumiko; Zhou, Haoshen

    2012-05-14

    The 'composite' layered materials for lithium-ion batteries have recently attracted great attention owing to their large discharge capacities. Here, the 0.5Li(2)MnO(3)·0.5LiMn(0.42)Ni(0.42)Co(0.16)O(2)'composite' layered manganese-rich material is prepared and characterized by the synchrotron X-ray powder diffraction (SXPD). The relationship between its electrochemical performance and its 'composite' components, the Li(2)MnO(3) phase activation process during cycling and the cycle stability of this material at room temperature are elucidated based on its kinetic controlled electrochemical properties, dQ/dV curves and Raman scattering spectroscopies associated with different initial charge-discharge current densities (5 mA g(-1), 20 mA g(-1) and 50 mA g(-1)), cut-off voltages (4.6 V and 4.8 V) and cycle numbers (50 cycles and 150 cycles). Furthermore, its reaction pathways are tracked via a firstly introduced integrated compositional phase diagram of four components, Li(2)MnO(3), LiMn(0.42)Ni(0.42)Co(0.16)O(2), MO(2) (M = Mn(1-?-?)Ni(?)Co(?); 0 ??? 5/12, 0 ??? 1/6) and LiMnO(2), which turns out to be a very important guiding tool for understanding and utilizing this 'composite' material. PMID:22456724

  14. 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.

  15. Strong phonon scattering by layer structured PbSnS{sub 2} in PbTe based thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiaqing [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois (United States); Department of Chemistry, Northwestern University, Evanston, Illinois (United States); Frontier Inititute of Science and Technology, Xi' an Jiaotong University, Xi' an (China); Girard, Steven N.; Zhao, Lidong; Kanatzidis, Mercouri G. [Department of Chemistry, Northwestern University, Evanston, Illinois (United States); Zheng, Jin-Cheng [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen (China); Dravid, Vinayak P. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois (United States)

    2012-08-22

    The incorporation of PbSnS{sub 2} in PbTe results in a tremendous reduction of the lattice thermal conductivity to 0.8 W/mK at room temperature, a reduction of almost 60% over bulk PbTe. Transmission electron microscopy reveals very high density displacement layers, misfit dislocations, and phase boundaries. Our thermal transport calculations based on modified Debye-Callaway model, well in agreement with the experimental measurements, reveal that the layer structured PbSnS{sub 2} plays an important role in reducing the lattice thermal conductivity. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Pure and Mn-doped La4SrTi5O17 layered perovskite as potential solid oxide fuel cell material: Structure and anodic performance

    Science.gov (United States)

    Périllat-Merceroz, Cédric; Roussel, Pascal; Huvé, Marielle; Capoen, Edouard; Rosini, Sébastien; Gélin, Patrick; Vannier, Rose-Noëlle; Gauthier, Gilles H.

    2015-01-01

    Pure and 5% Mn doped layered perovskites La4SrTi5O17, members of the La4Srn-4(Ti,Mn)nO3n+2 series with n = 5, have been synthesized and investigated as anode materials for Solid Oxide Fuel Cells. The use of XRD, neutron and electron diffraction techniques allows clarifying some divergences concerning the structural characterization within the family, not only in air but also in anodic-like N2/H2(97/3) atmosphere. The electrical conductivity of both compounds is very low in air but those values increase by two orders of magnitude in diluted hydrogen. The study of catalytic properties for methane steam reforming as well as in-depth analysis of the SOFC anodic behaviour of both materials are described, for which a microstructure optimization of the electrode allows to demonstrate the potential interest of the lamellar materials upon the classical three-dimensional cubic-like LSTs.

  17. 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.

  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. 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

  20. Unusual Application Of Ion Beam Analysis For The Study Of Surface Layers On Materials Relevant To Cultural Heritage

    International Nuclear Information System (INIS)

    Recently a new thematic of research -- intentional patinas on antic copper-base objects -- lead the AGLAE (Accelerateur Grand Louvre pour l'Analyse Elementaire) team of the C2RMF (Centre de Recherche et de Restauration des Musees de France) to improve its methods of analyzing thin surface layers both in their elemental composition and in-depth elemental distribution. A new beam extraction set-up containing a particle detector has been developed in order to use a 6 MeV alpha beam both in PIXE and RBS mode and to monitor precisely the ion dose received by the sample. Both RBS and ionization cross sections were assessed in order to make sure that the analysis can be quantitative. This set up allows great progresses in the understanding of both nature and structure of this very particular oxide layer obtained in the antiquity by chemical treatment on copper alloys, containing gold and/or silver and presenting very interesting properties of color and stability.Besides the non destructive properties of the IBA in external beam mode, this method of analyzing allows the study of samples in interaction with its environment. This was used to study the high temperature oxidation of Cu-Sn alloys using a furnace developed in order to heat a sample and analyze it in RBS mode at the same time. This new way of studying the growth of oxide layers permits to understand the oxidation mechanism of this system and to propose an experimental model for the identification of oxide layers duefor the identification of oxide layers due to an exposition to a high temperature, model needed for a long time by curators in charge of the study and the conservation of archaeological bronzes

  1. Forming openings to semiconductor layers of silicon solar cells by inkjet printing

    Energy Technology Data Exchange (ETDEWEB)

    Lennon, Alison J.; Utama, Roland Y.; Lenio, Martha A.T.; Ho-Baillie, Anita W.Y.; Kuepper, Nicole B.; Wenham, Stuart R. [The University of New South Wales, ARC Photovoltaics Centre of Excellence, Sydney 2052 (Australia)

    2008-11-15

    An inkjet printing method for forming openings to buried semiconductor layers of silicon solar cells is described. The method uses an overlying resist as a sacrificial layer onto which a plasticiser for the resist polymer is deposited in a programmed pattern using inkjet printing. At the locations where the plasticiser is printed, the resist becomes permeable to aqueous etching solutions, enabling openings to be created in underlying dielectric or silicon layer(s). The formed openings can be used to create metal contacts to the buried silicon layers of the solar cell. The permeability of the resist to aqueous etchants can be reversed, thus enabling a single resist layer to be used to create more than one set of openings in the underlying layers. The proposed method may also be applied more generally to the formation of patterns of openings in layers of semiconductor or microelectromechanical devices. (author)

  2. Ultrasonic NDE for Internal Defect Detection in Multi-layered Composite Materials by Multi-resolution Signal Decomposition

    Directory of Open Access Journals (Sweden)

    Barkawi Sahari

    2013-01-01

    Full Text Available Ultrasonic NDE has been a well known approach to investigate materials microstructures, mechanical properties and structure integrity in industry. The internal structure of a material and position of anomalies can be recognised by the reactions of different materials to ultrasound. However, the interpretation of ultrasound signals is difficult in composite material inspection task due to the fact that the ultrasonic pulse is reflected not only by the defect occurred within the material but the microstructures and multiple lay ups of the material. This phenomenon causes the backscattering noise to hinder the real defects signal during the inspection. Backscattering noise exists in multiple frequencies. The objective of this study was to develop a new noise reduction method to enhance the defect detectability in coarse-grained structure material such as composites materials. This method increases Signal-to-noise Ratio (SNR by means of decomposing the original signal into multiresolution representations. To prevent the loss of information, the signal is processed in both temporal and frequency domain. The proposed method has been tested on simulated signal and Glass Fiber Reinforced Plastics (GFRP laminates. Both simulation and experimental results showed that this method can significantly reduce grain noise while preserving the resolution of the original signal of the defect.

  3. First-Principles Study on the Thermal Stability of LiNiO2 Materials Coated by Amorphous Al2O3 with Atomic Layer Thickness.

    Science.gov (United States)

    Kang, Joonhee; Han, Byungchan

    2015-06-01

    Using first-principles calculations, we study how to enhance thermal stability of high Ni compositional cathodes in Li-ion battery application. Using the archetype material LiNiO2 (LNO), we identify that ultrathin coating of Al2O3 (0001) on LNO(012) surface, which is the Li de-/intercalation channel, substantially improves the instability problem. Density functional theory calculations indicate that the Al2O3 deposits show phase transition from the corundum-type crystalline (c-Al2O3) to amorphous (a-Al2O3) structures as the number of coating layers reaches three. Ab initio molecular dynamic simulations on the LNO(012) surface coated by a-Al2O3 (about 0.88 nm) with three atomic layers oxygen gas evolution is strongly suppressed at T = 400 K. We find that the underlying mechanism is the strong contacting force at the interface between LNO(012) and Al2O3 deposits, which, in turn, originated from highly ionic chemical bonding of Al and O at the interface. Furthermore, we identify that thermodynamic stability of the a-Al2O3 is even more enhanced with Li in the layer, implying that the protection for the LNO(012) surface by the coating layer is meaningful over the charging process. Our approach contributes to the design of innovative cathode materials with not only high-energy capacity but also long-term thermal and electrochemical stability applicable for a variety of electrochemical energy devices including Li-ion batteries. PMID:25980957

  4. 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

  5. Presentation of a reference material for the spatially resolved hydrogen analytics in near-surface layers by means of nuclear-reaction analysis

    International Nuclear Information System (INIS)

    The object of the thesis is the presentation of the theory of the 15N-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 15N 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

  6. 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

  7. 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

    2015-01-01

    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. PMID:25999238

  8. Clean technology for the ultra barrier layer production: Presentation held at Flat Panel Display Materials and Manufacturing Equipment; 36th Working Group Meeting of the German Flat Panel Display Forum (DFF), December 8/9, 2010, Stuttgart

    OpenAIRE

    Bu?rger, Frank

    2010-01-01

    Thin film based industries (OLED; Organic photovoltaic, CIS-thin film photovoltaic) require very dense layers. Fraunhofer IPA investigations showed that besides process parameters also contamination have an impact on the barrier of a layers. The main contamination risks are particles on substrates regarding layer penetration. Airborne molecular contamination (AMC) caused e.g. by out-gassing of materials can have a strong impact as well.

  9. Encapsulated Fe3O4 nanoparticles with silica thin layer as an anode material for lithium secondary batteries

    International Nuclear Information System (INIS)

    Fe3O4 nanoparticles were coated with a SiO2 layer by using a modified sol-gel method. The synthetic procedures for Fe3O4 nanoparticles encapsulated with a SiO2 layer (SiO2-Fe3O4) consist of three consecutive steps: (i) fabrication of Fe3O4 by the co-precipitation method, (ii) stabilization of Fe3O4 with citrate as a capping agent, which is used to prevent particles from aggregating, and (iii) silica encapsulation by a modified sol-gel reaction. Based on the experimental range, SiO2-Fe3O4 exhibited higher cyclic performance than the intrinsic one. The reversible capacity of Fe3O4 with SiO2 at the first cycle was 363 mA h g-1 and the remaining discharge capacity was 321 mA h g-1 after the 30th cycle.

  10. New layered structures of cuprous chalcogenides as thin film solar cell materials: Cu2Te and Cu2Se.

    Science.gov (United States)

    Nguyen, Manh Cuong; Choi, Jin-Ho; Zhao, Xin; Wang, Cai-Zhuang; Zhang, Zhenyu; Ho, Kai-Ming

    2013-10-18

    The stable crystal structures of two cuprous chalcogenides of Cu2X (X=Te or Se) are predicted using an adaptive genetic algorithm in combination with first-principles density functional theory calculations. Both systems are found to prefer a unique and previously unrecognized layered structure, with the total energies much lower than all structures proposed in the literature so far. The newly discovered structures are further shown to be dynamically and mechanically stable, and possess electronic properties consistent with existing experimental observations. In particular, their layered nature is expected to prevail over other structural forms at the interfaces of thin-film solar cells, and knowledge about the precise atomic structures of the interfaces is a prerequisite for achieving long-term stability and high efficiency of CdTe and Cu(In,Ga)Se2 solar cells. PMID:24182279

  11. Unusual Application Of Ion Beam Analysis For The Study Of Surface Layers On Materials Relevant To Cultural Heritage

    Science.gov (United States)

    Mathis, F.; Salomon, J.; Trocellier, P.; Aucouturier, M.

    2006-12-01

    Recently a new thematic of research — intentional patinas on antic copper-base objects — lead the AGLAE (Accélérateur Grand Louvre pour l'Analyse Elémentaire) team of the C2RMF (Centre de Recherche et de Restauration des Musées de France) to improve its methods of analyzing thin surface layers both in their elemental composition and in-depth elemental distribution. A new beam extraction set-up containing a particle detector has been developed in order to use a 6 MeV alpha beam both in PIXE and RBS mode and to monitor precisely the ion dose received by the sample. Both RBS and ionization cross sections were assessed in order to make sure that the analysis can be quantitative. This set up allows great progresses in the understanding of both nature and structure of this very particular oxide layer obtained in the antiquity by chemical treatment on copper alloys, containing gold and/or silver and presenting very interesting properties of color and stability. Besides the non destructive properties of the IBA in external beam mode, this method of analyzing allows the study of samples in interaction with its environment. This was used to study the high temperature oxidation of Cu-Sn alloys using a furnace developed in order to heat a sample and analyze it in RBS mode at the same time. This new way of studying the growth of oxide layers permits to understand the oxidation mechanism of this system and to propose an experimental model for the identification of oxide layers due to an exposition to a high temperature, model needed for a long time by curators in charge of the study and the conservation of archaeological bronzes.

  12. Method of manufacturing a fully integrated and encapsulated micro-fabricated vacuum diode

    Science.gov (United States)

    Resnick, Paul J.; Langlois, Eric

    2014-08-26

    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.

  13. 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

  14. Quantum size effects in layered VX2 (X = S, Se) materials: Manifestation of metal to semimetal or semiconductor transition

    Science.gov (United States)

    Wasey, A. H. M. Abdul; Chakrabarty, Soubhik; Das, G. P.

    2015-02-01

    Most of the two dimensional (2D) transition metal dichalcogenides (TMDC) are nonmagnetic in pristine form. However, 2D pristine VX2 (X = S, Se, Te) materials are found to be ferromagnetic. Using spin polarized density functional theory (DFT) calculations, we have studied the electronic, magnetic, and surface properties of this class of materials in both trigonal prismatic H- and octahedral T-phase. Our calculations reveal that they exhibit materially different properties in those two polymorphs. Most importantly, detailed investigation of electronic structure explored the quantum size effect in H-phase of these materials thereby leading to metal to semimetal (H-VS2) or semiconductor (H-VSe2) transition when downsizing from bilayer to corresponding monolayer.

  15. Sacrificial hydrogen generation from aqueous triethanolamine with Eosin Y-sensitized Pt/TiO2 photocatalyst in UV, visible and solar light irradiation.

    Science.gov (United States)

    Chowdhury, Pankaj; Gomaa, Hassan; Ray, Ajay K

    2015-02-01

    In this paper, we have studied Eosin Y-sensitized sacrificial hydrogen generation with triethanolamine as electron donor in UV, visible, and solar light irradiation. Aeroxide TiO2 was loaded with platinum metal via solar photo-deposition method to reduce the electron hole recombination process. Photocatalytic sacrificial hydrogen generation was influenced by several factors such as platinum loading (wt%) on TiO2, solution pH, Eosin Y to Pt/TiO2 mass ratio, triethanolamine concentration, and light (UV, visible and solar) intensities. Detailed reaction mechanisms in visible and solar light irradiation were established. Oxidation of triethanolamine and formaldehyde formation was correlated with hydrogen generation in both visible and solar lights. Hydrogen generation kinetics followed a Langmuir-type isotherm with reaction rate constant and adsorption constant of 6.77×10(-6) mol min(-1) and 14.45 M(-1), respectively. Sacrificial hydrogen generation and charge recombination processes were studied as a function of light intensities. Apparent quantum yields (QYs) were compared for UV, visible, and solar light at four different light intensities. Highest QYs were attained at lower light intensity because of trivial charge recombination. At 30 mW cm(-2) we achieved QYs of 10.82%, 12.23% and 11.33% in UV, visible and solar light respectively. PMID:25441927

  16. SiGe porous nanorod arrays as high-performance anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    Highlights: •SiGe porous nanorod arrays were synthesized via template-assisted method. •The SiGe porous nanorod arrays were used as anode materials of Li-ion batteries. •The SiGe porous nanorod arrays show better performance than planar electrode. •The porous structure and addition of Ge is responsible for the good performance. -- Abstract: We demonstrate the synthesis of SiGe porous nanorod arrays by using ZnO nanorod arrays as a sacrificial template. A seed-assisted method was employed to synthesize ZnO nanorod arrays which were coated by SiGe layer via a co-sputtering method. After the removal of ZnO nanorod, SiGe porous nanorod arrays were achieved. When used as an anode material of lithium-ion batteries, SiGe porous nanorod arrays showed enhanced performance compared to corresponding planar electrode and bare Si porous nanorod arrays. The good contact and adhesion of the porous nanorod arrays with the current collector, and the integration of Ge that can greatly improve the conductivity and lithium-ion diffusivity in SiGe layer, may be responsible for the enhanced performance

  17. 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

  18. Finite Element Analysis in Combination with Perfectly Matched Layer to the Numerical Modeling of Acoustic Devices in Piezoelectric Materials

    Directory of Open Access Journals (Sweden)

    Dbich Karim

    2013-05-01

    Full Text Available The characterization of finite length Surface Acoustic Wave (SAW and Bulk acoustic Wave (BAW resonators is addressed here. The Finite Element Analysis (FEA induces artificial wave reflections at the edges of the mesh. In fact, these ones do not contribute in practice to the corresponding experimental response. The Perfectly Matched Layer (PML method, allows to suppress the boundary reflections. In this work, we first demonstrate the basis of PML adapted to FEA formalism. Next, the results of such a method are depicted allowing a discussion on the behavior of finite acoustic resonators.

  19. Tuning the interfacial hole injection barrier between p-type organic materials and Co using a MoO3 buffer layer

    International Nuclear Information System (INIS)

    We demonstrate that the interfacial hole injection barrier ?h between p-type organic materials (i.e., CuPc and pentacene) and Co substrate can be tuned by the insertion of a MoO3 buffer layer. Using ultraviolet photoemission spectroscopy, it was found that the introduction of MoO3 buffer layer effectively reduces the hole injection barrier from 0.8 eV to 0.4 eV for the CuPc/Co interface, and from 1.0 eV to 0.4 eV for the pentacene/Co interface, respectively. In addition, by varying the thickness of the buffer, the tuning effect of ?h is shown to be independent of the thickness of MoO3 interlayer at both CuPc/Co and pentacene/Co interfaces. This Fermi level pinning effect can be explained by the integer charge-transfer model. Therefore, the MoO3 buffer layer has the potential to be applied in p-type organic spin valve devices to improve the device performance via reducing the interfacial hole injection barrier.

  20. 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

  1. 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.

  2. 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.

  3. Are there generic mechanisms governing interactions between nanoparticles and cells? Epitope mapping the outer layer of the protein material interface

    Science.gov (United States)

    Lynch, Iseult

    2007-01-01

    In this paper we discuss the possibility of a general paradigm for cell-biomaterial and cell-nanoparticle interactions. The basis of the paradigm is that the nature of the biomaterial or nanoparticle surface is not the important parameter, but rather the nature of the outermost layer of adsorbed proteins as well as long-lived misfolded proteins shed from the surfaces. If the adsorbed protein is irreversibly adsorbed onto the surface it may be sufficiently disrupted so that a variety of peptide units (here termed “cryptic epitopes”) not usually expressed in nature at the surface of the protein become exposed. Similarly, where there is a slow exchange time with the surface, surface-induced perturbations may lead to long-lived misfolded proteins being shed from the surface and continuing to express altered surface peptide sequences. In cases where the proteins have lost most of their tertiary structure, anomalous peptide sequences and geometries that are not displayed at the surface by the native protein may in fact be presented after surface adsorption of a protein. Such anomalous surface expressions could contain novel epitopes that trigger various signalling pathways or even diseases. Thus, future approaches to understanding cell-biomaterial and cell-nanoparticle interactions should focus on characterising the outer layer of the adsorbed proteins, or “epitope mapping” as well as examining the possibility of formation of essentially “new” proteins as a result of desorption of conformationally or geometrically altered proteins.

  4. Thermal Response and Stability Characteristics of Bistable Composite Laminates by Considering Temperature Dependent Material Properties and Resin Layers

    Science.gov (United States)

    Moore, M.; Ziaei-Rad, S.; Salehi, H.

    2013-02-01

    In this study, the stability characteristics and thermal response of a bistable composite plate with different asymmetric composition were considered. The non-linear finite element method (FEM) was utilized to determine the response of the laminate. Attention was focused on the temperature dependency of laminate mechanical properties, especially on the thermal expansion coefficients of the composite graphite-epoxy plate. Also the effect of including the resin layers on the stability characteristics of the laminate was investigated. The effect of the temperature on the laminate cured configurations in the range of 25°C to 180°C and -60°C to 40°C was examined. The results indicate that the coefficient of thermal expansions has a major effect on the cured shapes. Next, optical microscopy was used to characterize the laminate composition and for the first time the effect of including the resin layers on the actuation loads that causes snapping behavior between two stable shapes was studied. The results obtained from the finite element simulations were compared with experimental results and a good correlation was obtained. Finally, the stability characteristics of a tapered composite panel were investigated for using in a sample winglet as a candidate application of bistable structures.

  5. 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.

  6. 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).

  7. Nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets with a 3D nanonetwork structure as supercapacitive materials

    International Nuclear Information System (INIS)

    Graphical abstract: The microwave heating reflux approach was developed for the fabrication of nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets, in which ammonia and ethanol were used as the precipitator and medium for the synthesis. The obtained composite shows a 3D flowerclusters morphology with nanonetwork structure and largely enhanced supercapacitive performance. - Highlights: • The paper reported the microwave synthesis of nickel–cobalt layered double hydroxide/graphene composite. • The novel synthesis method is rapid, green, efficient and can be well used to the mass production. • The as-synthesized composite offers a 3D flowerclusters morphology with nanonetwork structure. • The composite offers excellent supercapacitive performance. • This study provides a promising route to design and synthesis of advanced graphene-based materials with the superiorities of time-saving and cost-effective characteristics. - Abstract: The study reported a novel microwave heating reflux method for the fabrication of nickel–cobalt layered double hydroxide ultrathin nanoflakes decorated on graphene sheets (GS/NiCo-LDH). Ammonia and ethanol were employed as precipitant and reaction medium for the synthesis, respectively. The resulting GS/NiCo-LDH offers a 3D flowerclusters morphology with nanonetwork structure. Due to the greatly enhanced rate of electron transfer and mass transport, the GS/NiCo-LDH electrode exhibits excellent supercapacitive performances. The maximum specific capacitance was found to be 1980.7 F g?1 at the current density of 1 A g?1. The specific capacitance can remain 1274.7 F g?1 at the current density of 15 A g?1 and it has an increase of about 2.9% after 1500 cycles. Moreover, the study also provides a promising approach for the design and synthesis of metallic double hydroxides/graphene hybrid materials with time-saving and cost-effective characteristics, which can be potentially applied in the energy storage/conversion devices

  8. Sacrificial Bonds in Polymer Brushes from Rat Tail Tendon Functioning as Nanoscale Velcro

    OpenAIRE

    Gutsmann, Thomas; Hassenkam, Tue; Cutroni, Jacqueline A.; Hansma, Paul K.

    2005-01-01

    Polymers play an important role in many biological systems, so a fundamental understanding of their cross-links is crucial not only for the development of medicines but also for the development of biomimetic materials. The biomechanical movements of all mammals are aided by tendon fibrils. The self-organization and biomechanical functions of tendon fibrils are determined by the properties of the cross-links between their individual molecules and the interactions among the cross-links. The cro...

  9. High electrochemical selectivity of edge versus terrace sites in two-dimensional layered MoS2 materials.

    Science.gov (United States)

    Wang, Haotian; Zhang, Qianfan; Yao, Hongbin; Liang, Zheng; Lee, Hyun-Wook; Hsu, Po-Chun; Zheng, Guangyuan; Cui, Yi

    2014-12-10

    Exploring the chemical reactivity of different atomic sites on crystal surface and controlling their exposures are important for catalysis and renewable energy storage. Here, we use two-dimensional layered molybdenum disulfide (MoS2) to demonstrate the electrochemical selectivity of edge versus terrace sites for Li-S batteries and hydrogen evolution reaction (HER). Lithium sulfide (Li2S) nanoparticles decorates along the edges of the MoS2 nanosheet versus terrace, confirming the strong binding energies between Li2S and the edge sites and guiding the improved electrode design for Li-S batteries. We also provided clear comparison of HER activity between edge and terrace sites of MoS2 beyond the previous theoretical prediction and experimental proof. PMID:25372985

  10. Plasma discharge efficiency increase by using a small bandgap protective layer material- first-principles study for Mg1-xZnxO

    Science.gov (United States)

    Li, Qiaofen; Tu, Yan; Tolner, Harm; Yang, Lanlan

    2011-05-01

    In this work, the properties of Mg1-xZnxO thin films are investigated as an example of a protective layer material with a small bandgap in a plasma display panel, to analyze the impact of these kinds of materials on the discharge properties. Using the first principles calculation method, the electronic structure of Mg1-xZnxO crystal is analyzed, and an analytical formula is obtained for the values of the bandgap. A cubic structure is obtained for x between 0 and 0.625. The secondary electron emission coefficients ? of Neon and Xenon with the Mg1-xZnxO films are then evaluated based on Hagstrum's theory. The ? value for Xe ions is zero, until a concentration of 0.375 is reached, when the bandgap is about 5.1 eV. At x = 0.375 and beyond the condition for Auger emission by xenon ions is fulfilled, and for x > 0.375 the ? value increases continuously until a value of 0.07 is reached for x = 0.625. The ? value for Ne increases from 0.25 to 0.38 when the ZnO proportion is increased from 0 to 0.625. The discharge characteristics of the SM-PDP with Mg1-xZnxO protective layer are then calculated using the fluid model. When increasing the x value, the working voltage is strongly reduced, while the discharge efficiency is enhanced by about 60% at 20% Xe for a change in x from 0 to 0.625. We find that this increase is mainly caused by increased electron excitation efficiency. Therefore mixed-oxide materials with a small bandgap like MgO-ZnO in principle enable the use of high xenon content plasma displays, while strongly increasing the discharge efficiency.

  11. Effect of graphene layer thickness and mechanical compliance on interfacial heat flow and thermal conduction in solid-liquid phase change materials.

    Science.gov (United States)

    Warzoha, Ronald J; Fleischer, Amy S

    2014-08-13

    Solid-liquid phase change materials (PCMs) are attractive candidates for thermal energy storage and electronics cooling applications but have limited applicability in state-of-the-art technologies due to their low intrinsic thermal conductivities. Recent efforts to incorporate graphene and multilayer graphene into PCMs have led to the development of thermal energy storage materials with remarkable values of bulk thermal conductivity. However, the full potential of graphene as a filler material for the thermal enhancement of PCMs remains unrealized, largely due to an incomplete understanding of the physical mechanisms that govern thermal transport within graphene-based nanocomposites. In this work, we show that the number of graphene layers (n) within an individual graphene nanoparticle has a significant effect on the bulk thermal conductivity of an organic PCM. Results indicate that the bulk thermal conductivity of PCMs can be tuned by over an order of magnitude simply by adjusting the number of graphene layers (n) from n = 3 to 44. Using scanning electron microscopy in tandem with nanoscale analytical techniques, the physical mechanisms that govern heat flow within a graphene nanocomposite PCM are found to be nearly independent of the intrinsic thermal conductivity of the graphene nanoparticle itself and are instead found to be dependent on the mechanical compliance of the graphene nanoparticles. These findings are critical for the design and development of PCMs that are capable of cooling next-generation electronics and storing heat effectively in medium-to-large-scale energy systems, including solar-thermal power plants and building heating and cooling systems. PMID:24983698

  12. Materials for solar hydrogen production with simultaneous mineralization of ethanol

    OpenAIRE

    C.M. Rangel; Silva, R A; T.I. Paiva; Charasse, B.

    2007-01-01

    The photo-catalytic production of hydrogen by means of irradiation of a suspension of semiconductor oxides presents attractive features over other methods with higher cost such as water electrolysis. In this work, photocatalytic hydrogen production from water is studied, using ethanol as sacrificial agent. New nanostructured multifunctionalised semiconductor materials based on titanium dioxide, with effective photo-catalytic properties under UV illumination were synthesized using sol-gel tech...

  13. Fabrication of monolithic polymer nanofluidic channels using nanowires as sacrificial templates

    Science.gov (United States)

    Chu, Kyo Seon; Kim, Seungwook; Chung, Haegeun; Oh, Joon-Ho; Seong, Tae-Yeon; An, Boo Hyun; Kim, Young Keun; Park, Jae Hyoung; Rag Do, Young; Kim, Woong

    2010-10-01

    We report a facile and reliable method to fabricate polymer-based monolithic nanofluidic channels. The nanochannels are obtained via three main steps: (1) fabrication of nanowire-transistor like structures, which are silver or zinc oxide nanowires horizontally bridging two electrodes made of zinc oxide on SiO2/Si substrates; (2) casting and curing polyimide solution on the nanowire structures; and (3) selective etching of the nanowire and electrode templates against the polyimide substrates. This process leads to the production of nanochannels with a diameter down to ~ 50 nm. Our method is based on nanowires that are chemically synthesized whereas nanopattern fabrication conventionally relies on expensive equipment. Moreover, the polymer nanochannels are fabricated monolithically while a process of bonding two different materials is required in traditional methods where leakage problems are often identified at the interface. Construction of nanofluidic circuitry could be expected in the future based on the current work.

  14. Fabrication of monolithic polymer nanofluidic channels using nanowires as sacrificial templates

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Kyo Seon; Kim, Seungwook; Chung, Haegeun; Oh, Joon-Ho; Seong, Tae-Yeon; An, Boo Hyun; Kim, Young Keun; Kim, Woong [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Park, Jae Hyoung; Do, Young Rag, E-mail: woongkim@korea.ac.kr [Department of Chemistry, Kookmin University, Seoul 136-702 (Korea, Republic of)

    2010-10-22

    We report a facile and reliable method to fabricate polymer-based monolithic nanofluidic channels. The nanochannels are obtained via three main steps: (1) fabrication of nanowire-transistor like structures, which are silver or zinc oxide nanowires horizontally bridging two electrodes made of zinc oxide on SiO{sub 2}/Si substrates; (2) casting and curing polyimide solution on the nanowire structures; and (3) selective etching of the nanowire and electrode templates against the polyimide substrates. This process leads to the production of nanochannels with a diameter down to {approx} 50 nm. Our method is based on nanowires that are chemically synthesized whereas nanopattern fabrication conventionally relies on expensive equipment. Moreover, the polymer nanochannels are fabricated monolithically while a process of bonding two different materials is required in traditional methods where leakage problems are often identified at the interface. Construction of nanofluidic circuitry could be expected in the future based on the current work.

  15. Fabrication of monolithic polymer nanofluidic channels using nanowires as sacrificial templates

    International Nuclear Information System (INIS)

    We report a facile and reliable method to fabricate polymer-based monolithic nanofluidic channels. The nanochannels are obtained via three main steps: (1) fabrication of nanowire-transistor like structures, which are silver or zinc oxide nanowires horizontally bridging two electrodes made of zinc oxide on SiO2/Si substrates; (2) casting and curing polyimide solution on the nanowire structures; and (3) selective etching of the nanowire and electrode templates against the polyimide substrates. This process leads to the production of nanochannels with a diameter down to ? 50 nm. Our method is based on nanowires that are chemically synthesized whereas nanopattern fabrication conventionally relies on expensive equipment. Moreover, the polymer nanochannels are fabricated monolithically while a process of bonding two different materials is required in traditional methods where leakage problems are often identified at the interface. Construction of nanofluidic circuitry could be expected in the future based on the current work.

  16. Results of analyzing the fast neutron penetration through shielding layers of heavy materials by invariant imbedding method

    International Nuclear Information System (INIS)

    In this paper calculations of fast neutron penetration through Fe and Pb as shielding materials is performed. The efficiency of combined method of the invariant imbedding and transfer matrix is treated. Transmitted and reflected fluxes for different shielding thicknesses for the case of the neutrons with distorted fission spectrum as well as for the plane source of unit intensity are obtained. Comparison of the result with the data from literature shows satisfactory accuracy of the applied method as well as shortening of the computer time, even for the larger shielding thicknesses (author)

  17. Formation of oxide layers on the materials IN 738 LC and IN 939, and on a CoCrAlY coating, in air and in a Na2SO4 environment

    International Nuclear Information System (INIS)

    Gas turbine blade materials are affected by corrosion processes due to aggressive combustion products as, e.g., Na2SO4, SO2/SO3, etc. The formation of oxide layers in air or in a Na2SO4 environment was investigated in order to reveal and characterize the damaging processes involved, tests being done at temperatures between 650deg C and 1100deg C. The experiments in air showed that on IN 738 LC and on IN 939, a layer rich in chromium develops, which is surrounded by an inner and an outer titanium oxide band. Due to the volume increase from internal oxidation of Al, internal nitrification of Ti, and oxidation of the refractory carbides in the initial oxidation phase, the metal cases are undergoing deformation, so that the surface layer is cracking and the aggressive media can reach the base materials. Sufficient pre-oxidation completely, or almost completely, prevents cracking so that the surface layer to a large extent protects the base material against corrosive attack by sulfates. On the CoCrAlY coating, an Al2O3 layer is formed. Both Y and Ti in the base material may impair the protective effect due to their participation in the oxide layer formation process. (orig.) With 97 figs., 3 tabs

  18. 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.

  19. 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.

  20. 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

  1. Effective material parameter retrieval for thin sheets: Theory and application to graphene, thin silver films, and single-layer metamaterials

    International Nuclear Information System (INIS)

    An important tool in the field of metamaterials is the extraction of effective material parameters from simulated or measured scattering parameters of a sample. Here we discuss a retrieval method for thin-film structures that can be approximated by a two-dimensional scattering sheet. We determine the effective sheet conductivity from the scattering parameters and we point out the importance of the magnetic sheet current to avoid an overdetermined inversion problem. Subsequently, we present two applications of the sheet retrieval method. First, we determine the effective sheet conductivity of thin silver films and we compare the resulting conductivities with the sheet conductivity of graphene. Second, we apply the method to a cut-wire metamaterial with an electric dipole resonance. The method is valid for thin-film structures such as two-dimensional metamaterials and frequency-selective surfaces and can be easily generalized for anisotropic or chiral media.

  2. Effective material parameter retrieval for thin sheets: Theory and application to graphene, thin silver films, and single-layer metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Tassin, Philippe, E-mail: tassin@ameslab.gov [Ames Laboratory - U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Koschny, Thomas, E-mail: koschny@ameslab.gov [Ames Laboratory - U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Soukoulis, Costas M., E-mail: soukoulis@ameslab.gov [Ames Laboratory - U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Institute of Electronic Structure and Lasers (IESL), FORTH, 71110 Heraklion, Crete (Greece)

    2012-10-15

    An important tool in the field of metamaterials is the extraction of effective material parameters from simulated or measured scattering parameters of a sample. Here we discuss a retrieval method for thin-film structures that can be approximated by a two-dimensional scattering sheet. We determine the effective sheet conductivity from the scattering parameters and we point out the importance of the magnetic sheet current to avoid an overdetermined inversion problem. Subsequently, we present two applications of the sheet retrieval method. First, we determine the effective sheet conductivity of thin silver films and we compare the resulting conductivities with the sheet conductivity of graphene. Second, we apply the method to a cut-wire metamaterial with an electric dipole resonance. The method is valid for thin-film structures such as two-dimensional metamaterials and frequency-selective surfaces and can be easily generalized for anisotropic or chiral media.

  3. Deposition temperature dependence of material and Si surface passivation properties of O3-based atomic layer deposited Al2O3-based films and stacks

    International Nuclear Information System (INIS)

    The material composition and the Si surface passivation of aluminum oxide (Al2O3) films prepared by atomic layer deposition using Al(CH3)3 and O3 as precursors were investigated for deposition temperatures (TDep) between 200?°C and 500?°C. The growth per cycle decreased with increasing deposition temperature due to a lower Al deposition rate. In contrast the material composition was hardly affected except for the hydrogen concentration, which decreased from [H]?=?3 at. % at 200?°C to [H]?2O3/SiNx stacks complemented the work and revealed similar levels of surface passivation as single-layer Al2O3 films, both for the chemical and field-effect passivation. The fixed charge density in the Al2O3/SiNx stacks, reflecting the field-effect passivation, was reduced by one order of magnitude from 3·1012?cm?2 to 3·1011?cm?2 when TDep was increased from 300?°C to 500?°C. The level of the chemical passivation changed as well, but the total level of the surface passivation was hardly affected by the value of TDep. When firing films prepared at of low TDep, blistering of the films occurred and this strongly reduced the surface passivation. These results presented in this work demonstrate that a high level of surface passivation can be achieved for Al2O3-based films and stacks over a wide range of conditions when the combination of deposition temperature and annealing or firing temperature is carefully chosen

  4. Morphologies, Processing and Properties of Ceramic Foams and Their Potential as TPS Materials

    Science.gov (United States)

    Stackpoole, Mairead; Simoes, Conan R.; Johnson, Sylvia M.

    2002-01-01

    The current research is focused on processing ceramic foams with compositions that have potential as a thermal protection material. The use of pre-ceramic polymers with the addition of sacrificial blowing agents or sacrificial fillers offers a viable approach to form either open or closed cell insulation. Our work demonstrates that this is a feasible method to form refractory ceramic foams at relatively low processing temperatures. It is possible to foam complex shapes then pyrolize the system to form a ceramic while retaining the shape of the unfired foam. Initial work focused on identifying suitable pre-ceramic polymers with desired properties such as ceramic yield and chemical make up of the pyrolysis product after firing. We focused on making foams in the Si system (Sic, Si02, Si-0-C), which is in use in current acreage TPS systems. Ceramic foams with different architectures were formed from the pyrolysis of pre-ceramic polymers at 1200 C in different atmospheres. In some systems a sacrificial polyurethane was used as the blowing agent. We have also processed foams using sacrificial fillers to introduce controlled cell sizes. Each sacrificial filler or blowing agent leads to a unique morphology. The effect of different fillers on foam morphologies and the characterization of these foams in terms of mechanical and thermal properties are presented. We have conducted preliminary arc jet testing on selected foams with the materials being exposed to typical re-entry conditions for acreage TPS and these results will be discussed. Foams processed using these approaches have bulk densities ranging from 0.15 to 0.9 g/cm3 and cell sizes ranging from 5 to 500 pm. Compression strengths ranged from 2 to 7 MPa for these systems. Finally, preliminary oxidation studies have been conducted on selected systems and will be discussed.

  5. Layered Ultrathin Coherent Structures (LUCS)

    International Nuclear Information System (INIS)

    A new class of superconducting materials, Layered Ultrathin Coherent Structures (LUCS) are described. These materials are produced by sequentially depositing ultrathin layers of materials using high rate magnetron sputtering or thermal evaporation. Strong evidence is presented that layers as thin as 10 A can be prepared in this fashion. Resistivity data indicates that the mean free path is layer thickness limited. A strong disagreement is found between the experimentally measured transition temperatures T/sub c/ and the T/sub c/'s calculated using the Cooper limit approximation. This is interpreted as a change in the band structure or the phonon structure of the material due to layering or to surfaces

  6. Porous carbohydrate-based materials via hard templating.

    Science.gov (United States)

    Kubo, Shiori; Demir-Cakan, Rezan; Zhao, Li; White, Robin J; Titirici, Maria-Magdalena

    2010-02-22

    Among various techniques, the hydrothermal carbonization (HTC) of biomass (either isolated carbohydrates or crude plants) is a promising candidate for the synthesis of novel carbon-based materials with a wide variety of potential applications. In this Minireview, we discuss various synthetic routes towards such porous carbon-based materials or composites through the HTC process, using the nanocasting procedure. We focus on the synthesis of carbon materials with different pore systems and morphologies directed by the presence of various nanostructured inorganic sacrificial templates. This method allows tailoring of the final structure via the tools of colloid and polymer science, leading to selectable material morphology for a wide range of applications. PMID:19885902

  7. 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)

  8. Diffusion cooling of thermal neutrons in the outer Plexiglas layer of a two-zone system with non-hydrogenous material inside

    International Nuclear Information System (INIS)

    Diffusion cooling of thermal neutron flux in a finite volume of a medium results from the leakage of neutrons. The cooling effect is particularly complex when the system consists of zones with different neutron scattering properties. A study is presented on the diffusion cooling in Plexiglas (hydrogenous material), which constitutes an outer cylindrical shell surrounding an inner cylinder made of a non-hydrogenous substance. The pulsed neutron method has been used. Numerous series of the desired pulsed neutron experiments in two-zone cylindrical systems have been substituted by Monte Carlo simulations. The decay constant of the fundamental mode in the time distribution of the pulsed thermal neutron flux has been determined in each experiment. The so-called theoretical decay constants (defined under a particular assumption) have been calculated as a function of the system geometry and neutron dynamic parameters including the diffusion cooling coefficient of the outer Plexiglas shell. The variability of this parameter has been determined from a combination of experimental and theoretical results. For a system with a theoretical decay constant varying between 12,000 and 34,000 s-1, the diffusion cooling coefficient of Plexiglas in the outer layer varies between 9000 and 4800 cm4 s-1 with the latter being close to the value for homogeneous material. A function has been obtained and successfully applied in interpreting real experiments usinlied in interpreting real experiments using Czubek's method of measuring the absorption cross-section of small samples

  9. Deterministic transfer of two-dimensional materials by all-dry viscoelastic stamping

    OpenAIRE

    Castellanos-gomez, Andres; Buscema, Michele; Molenaar, Rianda; Singh, Vibhor; Janssen, Laurens; Zant, Herre S. J.; Steele, Gary A.

    2013-01-01

    Deterministic transfer of two-dimensional crystals constitutes a crucial step towards the fabrication of heterostructures based on artificial stacking of two-dimensional materials. Moreover, control on the positioning of two-dimensional crystals facilitates their integration in complex devices, which enables the exploration of novel applications and the discovery of new phenomena in these materials. Up to date, deterministic transfer methods rely on the use of sacrificial po...

  10. De Um Ponto De Vista Filosófico, Poderá O Budismo Ser Uma Ciência Anti-Sacrificial? [doi: 10.15440/arf.2014.18505

    Directory of Open Access Journals (Sweden)

    Francisco Felizol Marques

    2014-04-01

    Full Text Available Tanto na tradição budista como no pensamento de Girard a ignorância e o desejo estão na base do sofrimento e da violência. A tradição budista coloca a ignorância, de que nada existe em si e por si, avydia, como causa de todos os sofrimentos ao gerar uma cadeia de desejo / aversão que nos leva a uma prisão desejante de objecto em objecto. A perspectiva girardiana coloca na origem da violência a ignorância do nosso desejo mimético. O sujeito ignora que, longe de ser livre, autónomo e diferenciado como lhe reza a “mentira romântica”, só deseja e quer por imitação de um modelo. Nem o sujeito existe livre por si, nem o objecto que julga livremente desejar. Enquanto este modelo vigorar, reagirá mais e mais violentamente às pretensões do sujeito; e mesmo que o sujeito ultrapasse seu modelo, buscará sofregamente outro e outro modelo, sempre condenada a uma insatisfação. Se a isto juntarmos a proximidade anti-sacrificial das duas perspectivas, patente na proximidade descritiva da roda do samsara e do tempo circular e sacrificial duma sociedade pagã, encontramos entre Girard e a tradição budista suficientes pontos comuns para um entendimento.

  11. 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 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.

  12. Polymer layered silicate nanocomposites

    OpenAIRE

    Zanetti, Marco

    2000-01-01

    Polymers filled with low amounts of layered silicate dispersed at nanoscale level are most promising materials characterized by a combination of chemical, physical and mechanical properties that cannot be obtained with macro- or microscopic dispersions of inorganic fillers. Polymer layered silicate nanocomposites can be obtained by insertion of polymer molecules in the galleries between the layers of phyllosilicate. Here, hydrated alkaline or alkaline earth metal cations are hosted which neu...

  13. Layers of the Skin

    Science.gov (United States)

    ... the cells fusing together into layers of tough, durable material, which continue to migrate up to the ... inner organs. It also stores fat as an energy reserve for the body. The blood vessels, nerves, ...

  14. 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.

  15. Combining linear polarization spectroscopy and the Representative Layer Theory to measure the Beer-Lambert law absorbance of highly scattering materials.

    Science.gov (United States)

    Gobrecht, Alexia; Bendoula, Ryad; Roger, Jean-Michel; Bellon-Maurel, Véronique

    2015-01-01

    Visible and Near Infrared (Vis-NIR) Spectroscopy is a powerful non destructive analytical method used to analyze major compounds in bulk materials and products and requiring no sample preparation. It is widely used in routine analysis and also in-line in industries, in-vivo with biomedical applications or in-field for agricultural and environmental applications. However, highly scattering samples subvert Beer-Lambert law's linear relationship between spectral absorbance and the concentrations. Instead of spectral pre-processing, which is commonly used by Vis-NIR spectroscopists to mitigate the scattering effect, we put forward an optical method, based on Polarized Light Spectroscopy to improve the absorbance signal measurement on highly scattering samples. This method selects part of the signal which is less impacted by scattering. The resulted signal is combined in the Absorption/Remission function defined in Dahm's Representative Layer Theory to compute an absorbance signal fulfilling Beer-Lambert's law, i.e. being linearly related to concentration of the chemicals composing the sample. The underpinning theories have been experimentally evaluated on scattering samples in liquid form and in powdered form. The method produced more accurate spectra and the Pearson's coefficient assessing the linearity between the absorbance spectra and the concentration of the added dye improved from 0.94 to 0.99 for liquid samples and 0.84-0.97 for powdered samples. PMID:25467494

  16. 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

  17. 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 sp3 bonds in DLC coatings. The results show that commercially interesting coatings can be achieved in short time.

  18. Investigation of the ion storage/transfer behavior in an electrical double-layer capacitor by using ordered microporous carbons as model materials.

    Science.gov (United States)

    Nishihara, Hirotomo; Itoi, Hiroyuki; Kogure, Taichi; Hou, Peng-Xiang; Touhara, Hidekazu; Okino, Fujio; Kyotani, Takashi

    2009-01-01

    An ordered microporous carbon, which was prepared with zeolite as a template, was used as a model material to understand the ion storage/transfer behavior in electrical double-layer capacitor (EDLC). Several types of such zeolite-templated carbons (ZTCs) with different structures (framework regularity, particle size and pore diameter) were prepared and their EDLC performances were evaluated in an organic electrolyte solution (1 M Et(4)NBF(4)/propylene carbonate). Moreover, a simple method to evaluate a degree of wettability of microporous carbon with propylene carbonate was developed. It was found that the capacitance was almost proportional to the surface area and this linearity was retained even for the carbons with very high surface areas (>2000 m(2) g(-1)). It has often been pointed out that thin pore walls limit capacitance and this usually gives rise to the deviation from linearity, but such a limitation was not observed in ZTCs, despite their very thin pore walls (a single graphene, ca. 0.34 nm). The present study clearly indicates that three-dimensionally connected and regularly arranged micropores were very effective at reducing ion-transfer resistance. Despite relatively small pore diameter ZTCs (ca. 1.2 nm), their power density remained almost unchanged even though the particle size was increased up to several microns. However, when the pore diameter became smaller than 1.2 nm, the power density was decreased due to the difficulty of smooth ion-transfer in such small micropores. PMID:19338036

  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