WorldWideScience
1

MEMS Cantilevers - Sacrificial Layer Removal  

Science.gov (United States)

This animation, created by Southwest Center for Microsystems Education (SCME), "illustrates the removal or etch of the sacrificial layer of silicon dioxide. Removing this layer allows the micro-cantilevers to move. Such cantilevers are used as sensors for a variety of applications." The supporting MEMS Cantilever Learning Modules and activities can be downloaded from the SCME website under Educational Materials.

2

Benefit effort relation of sacrificial layers  

International Nuclear Information System (INIS)

The facilities to influence the interaction between melt and the concrete foundation by a sacrificial layer was investigated by the help of the code SACRI. The results of this investigation show that a relative moderation of the course of the accident can be realized by a simple sacrificial layer. FeO or basalt are suitable sacrificial materials. On principle, the long-term embankment of the melt can be attaind with an insulating casing round the sacrificial bed. This measure would require a considerable effort and has an impact on the containment pressure. (orig./HP)

3

Sacrificial materials for SFR severe accident mitigation  

International Nuclear Information System (INIS)

In case of postulated Sodium Fast Reactor severe accidents, the core could melt and form a mixture called corium. In this event, sacrificial materials could then be used to reduce the heat load to the retention structure and to avoid the criticality risk. This approach was applied in the past with, for instance, depleted uranium oxide used as sacrificial material in the SNR300 ex-vessel core catcher. A review of sacrificial material candidates has been conducted, considering both neutron absorber and diluent materials. This review was initially based on criteria related to thermophysical and chemical thermodynamic properties (melting and boiling temperature, ability to form a liquid solution with molten fuel...). Neutronic calculations have been done for some generic configurations in order to estimate the reactivity decrease due to the mixing of corium with some different materials. Materials such as aluminium oxide, uranium oxide and hafnium or europium oxides will be presented in more details and their relative advantages discussed. (authors)

4

Sacrificial layer for the fabrication of electroformed cantilevered LIGA microparts  

Science.gov (United States)

The use of silver filled PMMA as a sacrificial layer for the fabrication of multilevel LIGA microparts is presented. In this technique, a bottom level of standard electroformed LIGA parts is first produced on a metallized substrate such as a silicon wafer. A methyl methacrylate formulation mixed with silver particles is then cast and polymerized around the bottom level of metal parts to produce a conducting sacrificial layer. A second level of PMMA x-ray resist is adhered to the bottom level of metal parts and conducting PMMA and patterned to form another level of electroformed features. This presentation will discuss some the requirements for the successful fabrication of multilevel, cantilevered LIGA microparts. It will be shown that by using a silver filled PMMA, a sacrificial layer can be quickly applied around LIGA components; cantilevered microparts can be electroformed; and the final parts can be quickly released by dissolving the sacrificial layer in acetone.

Morales, Alfredo M.; Aigeldinger, Georg; Bankert, Michelle A.; Domeier, Linda A.; Hachman, John T.; Hauck, Cheryl; Keifer, Patrick N.; Krafcik, Karen L.; McLean, Dorrance E.; Yang, Peter C.

2003-01-01

5

PostCMOS compatible sacrificial layers for aluminum nitride microcantilevers  

Science.gov (United States)

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

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

2014-10-01

6

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

7

Cleaning graphene with a titanium sacrificial layer  

Energy Technology Data Exchange (ETDEWEB)

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.

Joiner, C. A., E-mail: cjoiner3@gatech.edu; Roy, T.; Hesabi, Z. R.; Vogel, E. M. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Chakrabarti, B. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080 (United States)

2014-06-02

8

Cleaning graphene with a titanium sacrificial layer  

Science.gov (United States)

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.

Joiner, C. A.; Roy, T.; Hesabi, Z. R.; Chakrabarti, B.; Vogel, E. M.

2014-06-01

9

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.

10

Self-standing polyelectrolyte multilayer films based on light-triggered disassembly of a sacrificial layer.  

Science.gov (United States)

In the present article, we present a new and convenient optical method for the preparation of self-standing polyelectrolyte multilayer films. This method employs the disassembly of a sacrificial layer stratum composed of five poly(acrylate, merocyanine) PMC/poly(diallyldimethylammonium chloride) PDADMAC bilayers, which is triggered by the irradiation with visible light. This leads to the conversion of the zwitterionic PMC to its neutral isomer poly(acrylate, spiropyran) PSP, whereby the attractive ionic interactions between the neighboring bilayers vanish. The disassembly of the sacrificial layers in deionized water was completed within 47 s, when in-situ monitored at the maximum absorbance of PSP (? = 360 nm), employing UV/visible spectrometry. Surprisingly, the disassembly duration of the sacrificial layers increased very little with an upper target film composed of 75 PDADMAC/PSS bilayers. The quick release of a thick target film (d ? 232 nm) composed of 100 (PDADMAC)/(PSS) bilayers in a large scale (7 × 18 mm(2)) could be ascribed not only to the vanished electrostatic attractive interaction between the layer pairs but also to increased hydrophobicity of the sacrificial layer element due to the photoisomerization of zwitterionic ionic PMC to neutral PSP. The unique advantages of this method as compared to the conventional approaches are demonstrated with the fast release (~2 min) of self-standing film combined with a well-defined, thin sacrificial layer (d ~ 30 nm). Moreover, harsh release conditions are also avoided, which significantly broadens the choice of materials that can be incorporated into the free-standing film. PMID:21981012

Pennakalathil, Jousheed; Hong, Jong-Dal

2011-11-22

11

Tuneable Capacitor based on dual picks profile of the sacrificial layer  

OpenAIRE

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...

Soulimane, S.; Casset, F.; Chapuis, F.; Charvet, P. -l; Ai?d, M.

2007-01-01

12

Thin polymer films as sacrificial layers for easier cleaning  

OpenAIRE

We propose a new approach for the removal of fouling agents from an interface. The interface is pre-coated with a polymer layer of a few nanometers thick that can be removed by a simple trigger such as a change in pH or salt concentration. When fouling agents adsorb on the interface, they can be removed by simply desorbing (sacrificing) the polymer coating. We show a proof of principle of this concept on the basis of two different types of sacrificial layers. The first system consists of a si...

Vos, W. M.; Keizer, A.; Cohen Stuart, M. A.; Kleijn, J. M.

2010-01-01

13

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

OpenAIRE

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...

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

2013-01-01

14

Metallization and Biopatterning on Ultra-Flexible Substrates via Dextran Sacrificial Layers  

Science.gov (United States)

Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS) layers (elastic moduli down to 3 kPa) utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself) were then readily transferrable to an elastomer surface following PDMS (10 to 70?1 base to crosslinker ratios) curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials. PMID:25153326

Tseng, Peter; Pushkarsky, Ivan; Di Carlo, Dino

2014-01-01

15

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

DEFF Research Database (Denmark)

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

Mohanty, Soumyaranjan Technical University of Denmark,

16

Method of using sacrificial materials for fabricating internal cavities in laminated dielectric structures  

Science.gov (United States)

A method of using sacrificial materials for fabricating internal cavities and channels in laminated dielectric structures, which can be used as dielectric substrates and package mounts for microelectronic and microfluidic devices. A sacrificial mandrel is placed in-between two or more sheets of a deformable dielectric material (e.g., unfired LTCC glass/ceramic dielectric), wherein the sacrificial mandrel is not inserted into a cutout made in any of the sheets. The stack of sheets is laminated together, which deforms the sheet or sheets around the sacrificial mandrel. After lamination, the mandrel is removed, (e.g., during LTCC burnout), thereby creating a hollow internal cavity in the monolithic ceramic structure.

Peterson, Kenneth A. (Albuquerque, NM)

2009-02-24

17

Photolithographic fabrication of arbitrarily shaped SU-8 microparticles without sacrificial release layers  

International Nuclear Information System (INIS)

We report on an efficient high throughput method for the photolithographic fabrication of well-defined arbitrarily shaped SU-8 microparticles without a sacrificial release layer. The procedure eliminates the spincoating of a sacrificial layer otherwise needed for particle lift-off, thereby reducing processing time and costs. Statistical analysis of the size distribution revealed a standard deviation of less than 2.3% in size. The particles can be immediately released into aqueous solution. This allows for anisotropical functionalization of the particles with, for example, biological loads or elements of molecular recognition after the development of the SU-8 structures. (technical note)

18

Improvement in semiconductor laser printing using a sacrificial protecting layer for organic thin-film transistors fabrication  

Energy Technology Data Exchange (ETDEWEB)

Laser-induced forward transfer (LIFT) has been used to deposit pixels of an organic semiconductor, distyryl-quaterthiophenes (DS4T). The dynamics of the process have been investigated by shadowgraphic imaging for the nanosecond (ns) and picosecond (ps) regime on a time-scale from the laser iradiation to 1.5 {mu}s. The morphology of the deposit has been studied for different conditions. Intermediate sacrificial layer of gold or triazene polymer has been used to trap the incident radiation. Its role is to protect the layer to be transferred from direct irradiation and to provide a mechanical impulse strong enough to eject the material.

Rapp, Ludovic, E-mail: rapp@lp3.univ-mrs.fr [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Cibert, Christophe [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Nenon, Sebastien [CINaM (Centre Interdisciplinaire de Nanoscience de Marseille) - UPR 3118 CNRS - Universite Aix Marseille, Case 913, Campus de Luminy, 13288 Marseille Cedex 09 (France); Alloncle, Anne Patricia [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Nagel, Matthias [Empa, Swiss Federal Laboratories for Materials Testing and Reasearch, Laboratory for Functional Polymers, Uberlandstrasse 129, 8600 Duebendorf (Switzerland); Lippert, Thomas [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen PSI (Switzerland); Videlot-Ackermann, Christine; Fages, Frederic [CINaM (Centre Interdisciplinaire de Nanoscience de Marseille) - UPR 3118 CNRS - Universite Aix Marseille, Case 913, Campus de Luminy, 13288 Marseille Cedex 09 (France); Delaporte, Philippe [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France)

2011-04-01

19

Improvement in semiconductor laser printing using a sacrificial protecting layer for organic thin-film transistors fabrication  

Science.gov (United States)

Laser-induced forward transfer (LIFT) has been used to deposit pixels of an organic semiconductor, distyryl-quaterthiophenes (DS4T). The dynamics of the process have been investigated by shadowgraphic imaging for the nanosecond (ns) and picosecond (ps) regime on a time-scale from the laser iradiation to 1.5 ?s. The morphology of the deposit has been studied for different conditions. Intermediate sacrificial layer of gold or triazene polymer has been used to trap the incident radiation. Its role is to protect the layer to be transferred from direct irradiation and to provide a mechanical impulse strong enough to eject the material.

Rapp, Ludovic; Cibert, Christophe; Nénon, Sébastien; Alloncle, Anne Patricia; Nagel, Matthias; Lippert, Thomas; Videlot-Ackermann, Christine; Fages, Frédéric; Delaporte, Philippe

2011-04-01

20

Improvement in semiconductor laser printing using a sacrificial protecting layer for organic thin-film transistors fabrication  

International Nuclear Information System (INIS)

Laser-induced forward transfer (LIFT) has been used to deposit pixels of an organic semiconductor, distyryl-quaterthiophenes (DS4T). The dynamics of the process have been investigated by shadowgraphic imaging for the nanosecond (ns) and picosecond (ps) regime on a time-scale from the laser iradiation to 1.5 ?s. The morphology of the deposit has been studied for different conditions. Intermediate sacrificial layer of gold or triazene polymer has been used to trap the incident radiation. Its role is to protect the layer to be transferred from direct irradiation and to provide a mechanical impulse strong enough to eject the material.

21

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

Science.gov (United States)

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

Ramadan, Khaled S.; Nasr, Tarek; Foulds, Ian G.

2013-03-01

22

Methods for making thin layers of crystalline materials  

Science.gov (United States)

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

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

2013-07-23

23

Porous silicon oxide sacrificial layers deposited by pulsed-direct current magnetron sputtering for microelectromechanical systems  

International Nuclear Information System (INIS)

The development of silicon oxide layers with high etch rates to be used as sacrificial layers in surface micromachining for microsystems fabrication poses a great technological challenge. In this work, we have investigated the possibility of obtaining easily removable silicon oxide layers by pulsed-direct current (DC) magnetron reactive sputtering. We have carried out a comprehensive study of the influence of the deposition parameters (total pressure and gas composition) on the composition, residual stress and lateral etch rate in fluoride wet solutions of the films. This study has allowed to determine the sputtering conditions to deposit, at high rates (up to 0.1 ?m/min), silicon oxide films with excellent characteristics for their use as sacrificial layers. Films with roughness around 5 nm rms, residual stress below 100 MPa and very high lateral etch rate (up to 5 ?m/min), around 70 times higher than for thermal silicon oxide, have been achieved. The structural characteristics of these easily removable silicon oxide layers have been assessed by infrared spectroscopy and atomic force microscopy, which have revealed that the films exhibit a porous structure, related to very specific sputter conditions. Finally, the viability of these films has been demonstrated by using them as sacrificial layer in the fabrication process of AlN-based microresonators.

24

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

DEFF Research Database (Denmark)

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.

Pouzet, Eric; De Cupere, Vinciane

2009-01-01

25

Photocatalytic acetaldehyde oxidation in air using spacious TiO2 films prepared by atomic layer deposition on supported carbonaceous sacrificial templates  

OpenAIRE

Supported carbon nanosheets and carbon nanotubes served as sacrificial templates for preparing spacious TiO2 photocatalytic thin films. Amorphous TiO2 was deposited conformally on the carbonaceous template material by atomic layer deposition (ALD). Upon calcination at 550{\\deg}C, the carbon template was oxidatively removed and the as-deposited continuous amorphous TiO2 layers transformed into interlinked anatase nanoparticles with an overall morphology commensurate to the or...

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

2014-01-01

26

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

OpenAIRE

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 &#...

Costescu Ruxandra; Deneke Christoph; Thurmer Dominic; Schmidt Oliver

2009-01-01

27

Formation of porous silicon using an ammonium fluoride based electrolyte for application as a sacrificial layer  

Science.gov (United States)

A new electrolyte is presented for the electrochemical formation of porous silicon. The electrolyte, an ammonium fluoride etch mixture (AFEM), is used instead of hydrofluoric acid (HF) which is normally used for porous silicon (PS) formation. The main advantage of AFEM is that it attacks aluminium at a significantly lower rate than HF thus allowing porous formation to be performed as a post-processing step, without the need to protect aluminium. This method has been applied to an epi-micromachining process where the epitaxial layer is used as the structural layer and a buried region of the p-type substrate is made porous (the sacrificial layer). Initial results are presented, with comparisons made to HF-formed porous layers, illustrated by SEM images of epi-micromachined structures.

Kuhl, M.; O'Halloran, G. M.; Gennissen, P. T. J.; French, P. J.

1998-12-01

28

New release technique of a thick sacrificial layer and residue effects on novel half-coaxial transmission line filters  

Science.gov (United States)

This paper presents a new release technique for efficient and complete removal of the thick sacrificial layer applicable to surface-micromachined devices and compares this with other conventional release methods. A fully surface-micromachined half-coaxial transmission line filter having a large air-filled gap of 100 µm in thickness is successfully demonstrated using the proposed release technique. The effects of the sacrificial layer residue on the RF responses of the filters, completed by a conventional oxygen plasma ashing process, are analyzed with the aid of x-ray photoelectron spectroscopy (XPS). Experiments show that the proposed new release technique makes it possible to completely remove the thick sacrificial layer, shorten the process time, increase the after-fabrication yield and improve the process reproducibility of the large air-filled gap filters compared to the conventional oxygen plasma ashing method.

Kim, Yongsung; Llamas-Garro, Ignacio; Baek, Chang-Wook; Kim, Jong-Man; Kim, Yong-Kweon

2009-05-01

29

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

Science.gov (United States)

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

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

30

Solidly mounted BAW resonators with layer-transferred AlN using sacrificial Si surfaces  

Science.gov (United States)

We present a new method to manufacture solidly mounted bulk acoustic wave resonators. This new process introduces the use of wafer bonding techniques and sacrificial surface removal to manufacture solidly mounted resonators having special properties. With the proposed process, Aluminum Nitride (AlN) thin films are obtained having exceptional c-axis crystal orientation with XRD rocking curve FWHM of 1.36° and material electromechanical coupling constant of 6.8% exceeding that of the epitaxial AlN electromechanical coupling constant. Fully functional single-mask resonators were successfully fabricated with this process working around 2.35 GHz and enjoying Q-values as high as 1300.

Abd Allah, Mohamed; Thalhammer, Robert; Kaitila, Jyrki; Herzog, Thomas; Weber, Werner; Schmitt-Landsiedel, Doris

2010-09-01

31

Sacrificial ion beam etching process for seed layer removal of 6 ?m pitch CuSn micro bumps  

International Nuclear Information System (INIS)

Copper pillar bumps show a wide-ranging application for assembly and packaging according to the 'More than Moore' roadmap. For the demand of higher input/output (I/O) densities and consequently smaller bump pitches the requirements on each process step in producing 6 ?m pitch Cu-Sn bumps increase. In this case the removal of seed layer with wet etchants is no longer practicable due to high undercut. A sacrifical Ion Beam Etching (IBE) process was developed for removing the TiW/Cu seed layer without any undercut. Due to the high etching rate of the rough Sn surface a sacrificial layer of Ni was used to protect the solder layer. To optimize the layer thicknesses etch rates were characterized. Special attention was directed to the etched material which covered the bumps on the sidewalls after the etching process step. Energy-dispersive X-ray spectroscopy (EDX) measurements and reflow processes revealed the influence of the redepositioned material on the melting behavior and hence on the following bonding process.

32

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

Directory of Open Access Journals (Sweden)

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.

Costescu Ruxandra

2009-01-01

33

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

Science.gov (United States)

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.

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

2009-12-01

34

Layered materials  

Science.gov (United States)

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.

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

2014-06-01

35

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)

36

Laboratory evaluation of sacrificial anode materials for cathodic protection of reinforced concrete bridges  

Energy Technology Data Exchange (ETDEWEB)

Laboratory evaluations were conducted on a series of anode materials that could be used for sacrificial cathodic protection (CP) of reinforced concrete bridge decks. These include Al, Mg, and Zn alloys. Anodes were fabricated into test coupons and coupled to small lengths of reinforcing steel. The anode-steel couples were placed in simulated concrete environments consisting of sealed containers filled with silica sand treated with a mixed alkali solution containing 6 kg/m{sup 3} of chloride ion by volume of sand. The treated sands were dried to obtain resistivities of 23 {Omega}-m, 100 {Omega}-m, and 260 {Omega}-m. Measurements of current flow, circuit resistance, potential, and depolarization were made over 18 weeks. Al and Zn anodes showed the most promise for use as galvanic anodes in reinforced concrete bridge decks.

Whiting, D.A.; Nagi, M.A. [Construction Technology Labs. Inc., Skokie, IL (United States); Broomfield, J.P. [Broomfield (J.P.), London (United Kingdom)

1996-06-01

37

Creation of freestanding wrinkled nano-films with desired deformation properties by controlling the surface morphology of a sacrificial layer  

Science.gov (United States)

Various wrinkle patterns can be formed due to the buckling of a stiff thin film on a compliant substrate. However, most wrinkled films previously reported were fixed on a large deformable substrate and thereby the potential deformability of the film was mechanically constrained by the substrate. In this study, we developed a technique for forming various wrinkled structures on the surface of a sacrificial resin layer. Since the sacrificial layer can be subsequently removed with a solvent, freestanding wrinkled films are created using the sacrificial layer. We found that a wrinkled structure is formed on the surface of the layer by applying a compressive strain to the resin layer at the appropriate moment during the hardening process. The wrinkle pattern depends on the curing time and the timing of the straining in two in-plane orthogonal directions. In addition to conventional stripe and labyrinth patterns by simple uniaxial and equi-biaxial strains, respectively, it was found that independent biaxial strains induce interesting structures, such as an orthogonally ordered wrinkle pattern and a nonsymmetrical buckling structure, in which the stripe array produced by the first straining remains and many finer wrinkles appear in each stripe by the second straining in the orthogonal direction. We conducted tensile experiments for 300-nm-thick freestanding Cu films having these wrinkled structures. The wrinkled nano-films have a variety of mechanical properties: the stripe structure has extremely high deformability (more than 10% strain) and reversibility, the labyrinth structure shows planar isotropic deformation, and the nonsymmetrical buckling structure has an anisotropic modulus and strength. Finite element analysis on the wrinkle structures revealed that the local stress concentration dominates the fracture limits.

Hirakata, Hiroyuki; Maruyama, Tomohiro; Yonezu, Akio; Minoshima, Kohji

2013-05-01

38

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

39

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

Scientific Electronic Library Online (English)

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.

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

40

Fabrication of polymer micro-devices based on organic sacrificial pastes  

OpenAIRE

We investigate in this work the fabrication of polymer micro-fluidic and micro-mechanical devices based on sublimable compounds as sacrificial layers, using a thick-film screen-printing deposition process. Fabrication of printed polymer microstructures featuring properties such as low cost, transparency and biocompatibility is particularly attractive and suitable for disposable biomedical devices. Channel, cavities and spacings for micro-devices are first defined by sacrificial material layer...

Serra, Nathalie; Maeder, Thomas; Gentsch, Olivier; Ryser, Peter

2010-01-01

41

A novel method to enhance the gettering efficiency in p-type Czochralski silicon by a sacrificial porous silicon layer  

Energy Technology Data Exchange (ETDEWEB)

A new two-step phosphorous diffusion gettering (TSPDG) process using a sacrificial porous silicon layer (PSL) is proposed. Due to a decrease in high temperature time, the TSPDG (PSL) process weakens the deterioration in performances of PSL, and increases the capability of impurity clusters to dissolve and diffuse to the gettering regions. By means of the TSPDG (PSL) process under conditions of 900 deg. C/60 min + 700 deg. C/30 min, the effective lifetime of minority carriers in solar-grade (SOG) Si is increased to 14.3 times its original value, and the short-circuit current density of solar cells is improved from 23.5 o 28.7 mA/cm{sup 2}, and the open-circuit voltage from 0.534 to 0.596 V along with the transform efficiency from 8.1% to 11.8%, which are much superior to the results achieved by the PDG (PSL) process at 900deg. C for 90 min. (semiconductor physics)

Zhang Caizhen; Wang Yongshun; Wang Zaixing, E-mail: wangysh@mail.lzjtu.cn [School of Electronic and Information Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China)

2011-03-15

42

Artificial Interface Deriving from Sacrificial Tris(trimethylsilyl)phosphate Additive for Lithium Rich Cathode Materials  

International Nuclear Information System (INIS)

Highlights: • Tris(trimethylsilyl)phosphate (TMSP) is investigated as a film-forming additive. • A modified SEI layer is formed due to the decomposition of TMSP additive. • Cells with 1.0 wt% TMSP exhibit enhanced cycle stability and rate performance. - Abstract: Tris(trimethylsilyl)phosphate (TMSP) has been investigated as an additive to form a modified solid electrolyte interface (SEI) on lithium rich cathode material Li[Li0.2Ni0.13Mn0.54Co0.13]O2 and improve its electrochemical performances. Linear sweep voltammetry (LSV) results show that TMSP additive decomposes at the potential ca. 4.1 V, lower than that of electrolyte solvent decomposition. The morphology images via TEM clearly demonstrate a continuous interfacial layer formed on the cathode surface after initial cycles. XPS results prove that the components of SEI are mainly derived from the decomposition of TMSP. The Li[Li0.2Ni0.13Mn0.54Co0.13]O2 cathode materials cycled in 1.0 wt% TMSP-containing electrolyte demonstrate obvious enhancement in its cycling stability and capacity retention reaches 91.1% after 50 cycles. The improved performances are ascribed to modified SEI which tightly covers on cathode particle, and effectively avoids a direct contact between cathode active material and electrolyte, leading to the stabilized interfacial structures

43

Sacrificial bridges for MEMS fabrication  

Science.gov (United States)

This study discusses sacrificial bridges that are used to release MEMS devices. Before being released, sacrificial bridges connect all the component structures into an integral structure. Solder bump bonding is used to mount the MEMS chip on another chip or a printed circuit board (PCB) and to maintain the alignment among all component structures after removal of the sacrificial bridges. Two types of sacrificial bridges were designed, analyzed and fabricated. The fabrication process—which used low resistivity single crystal silicon (SCS) wafers as the device material—was developed to implement the sacrificial bridges. Novel SCS through silicon vias (TSVs), which interconnect stacked chips, was made using the same process. An electrostatic comb drive actuator was fabricated and mounted onto a PCB. The fabricated actuator was tested to demonstrate the feasibility of the fabrication process, sacrificial bridges and SCS TSVs. The results show that the actuator worked well. Its maximum displacement and resonant frequency were 69.9 µm and 406 Hz, respectively. This method is promising for the delivery of a novel 3D system in package for MEMS devices.

Chang, Chao-Min; Chen, Yang-Che; Fong, Chien-Fu; Guu, Yunn-Horng; Chen, Rongshun; Yeh, J. Andrew; Hou, Max T.

2011-09-01

44

Formation of Nickel Silicide Layer on Strained-Si0.83Ge0.17/Si(001) using a Sacrificial Si Layer and its Morphological Instability  

Science.gov (United States)

Nickel silicide was formed on strained-Si0.83Ge0.17/Si(001) using a sacrificial Si capping (cap-Si) layer and its morphological characteristics were investigated. Nickel silicide layers were grown by rapid thermal annealing of the samples with the structure of Ni (\\cong 14 nm)/cap-Si (\\cong 26 nm)/Si0.83Ge0.17/Si(001) at the annealing temperature (TA) range of 400-800°C. The phase formation, surface and interfacial morphologies, and electrical properties of the resulting samples were characterized by various measurement techniques, including X-ray diffraction, atomic force microscopy, scanning electron microscopy, Auger electron spectroscopy, cross-sectional transmission electron microscopy, and the four-point probe method. The results showed the formation of a uniform layer nickel monosilicide (NiSi) with a thickness of {\\cong}30 nm at 400-550°C and sheet resistance values of 6.5-7.9 ?/\\square. The sheet resistance values of the samples annealed at TA? 600°C were found to be increased, however, and this is attributed to the agglomeration of nickel monosilicide leading to discrete large-size NiSi grains. Microstructural and chemical analyses of the samples annealed at elevated temperature, TA? 750°C, indicated the formation of large agglomerated NiSi grains penetrating into the Si0.83Ge0.17/Si(001) structure and the conversion of the cap-Si layer situated in between the nickel silicide grains into an Sil-uGeu layer (u \\cong 0.01--0.03), due to the out-diffusion of Ge from the SiGe layer during agglomeration. However, no NiSi2 phase was observed at these elevated annealing temperatures.

Jang, Chi Hwan; Shin, Dong Ok; Baik, Sung Il; Kim, Young-Woon; Song, Young-Joo; Shim, Kyu-Hwan; Lee, Nae-Eung

2005-07-01

45

The case for using a sacrificial layer of absorbent insulation in the design of flat and low-sloped roofing  

Science.gov (United States)

Beginning about twenty-five years ago, there was a marked increase in the number of single-ply membrane roof designs used to cover and waterproof flat and low-sloped building roofs. Over the past ten years, there has been a substantial increase in the number of installations of white and more reflective single-ply roof systems, mostly using high density cellular foam insulation in the substrate for insulation. A major factor in the increase in the popularity of these highly insulated and more reflective roof systems is the fact that many governments began offering incentives for building owners to use reflective coverings and better insulated roofs. Now, owing to the energy efficient requirements for the design and construction of new buildings put forth in ASHRAE Standard 90.1, "Energy Standard for Buildings Except Low-Rise Residential Buildings" and the world's apparent desire to be "green" (or at least appear to be), more and more roof designs will include these reflective single-ply membranes, which use the cellular foam insulation boards to meet these requirements. Using a lower density traditional insulation will mean that the roof will have to be very thick to comply, increasing the costs of installation. High density cellular foams do not absorb water until time, vapor pressure drive, UV and thermal shock break down the foam and it becomes more absorbent. This could be 5-7 years or longer, depending on the roof construction and other factors. This means that any water that enters the roof through a breach (leak) in the membrane goes straight into the building. This is not a good consequence since the failure mode of any roof is water entering the building. Keeping the water out of the building is the purpose of the waterproofing layer. This paper reviews the techniques of moisture testing on building roofs and infrared (IR) thermography, and puts forth the idea and reasoning behind having a sacrificial layer of very absorbent insulation installed in every flat and low-sloped roof so that when a breach occurs, it can easily be found, documented and repaired during an annual infrared inspection; as IR is an effective predictive maintenance technique and condition monitoring best practice for roof maintenance.

Stockton, Gregory R.

2013-05-01

46

Selection of sacrificial material to be applied in WWER-1000 corium catcher  

International Nuclear Information System (INIS)

Calculating-theoretical analysis of the required properties system of potential materials for the use as buffer material in WWER-1000 corium catcher was done. From the findings of the analysis Al2O3 and Fe2O3 were recommended as basic applicants. With regard to noted each by itself advantages and disadvantages the solid solutions formed by Al2O3 and Fe2O3 are of interest to practical implementation. Results of the evaluations are supported by the investigations into phase diagrams and reactions of active zone melt with oxide solutions based on the Al2O3 - Fe2O3 system

47

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

OpenAIRE

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

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

2009-01-01

48

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)

49

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)

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

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

2015-04-10

50

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

51

Illumination-dependent HF Etching of AlAs Sacrificial Layers for the Formation of ``Rolled Up'' Nanotubes from Strained InGaAs/GaAs Films  

Science.gov (United States)

"Rolled-up" nanostructures formed from lattice mismatched III-V heterojunction films by taking advantage of a strain-induced self-rolling mechanism represent a useful type of building blocks for nanotechnology, with possible applications in high-speed microelectronic and optoelectronic devices. This work investigated the effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up MBE grown InGaAs/GaAs bilayers. Based on this "etch suppression effect" (ESE), we propose an illumination-assisted technique that offers an advantage over other methods of rolling up nano-objects on a substrate from inherently strained films because it allows control over the positioning of rolled-up micro- and nanotubes independently from lithographic methods. For thicknesses of AlAs below 10 nm, we found 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, which can be used to realize well-controlled heterogeneously etched regions on the same sample.

Costescu, Ruxandra M.

2011-10-01

52

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.

53

Preferentially Etched Epitaxial Liftoff of InP Material  

Science.gov (United States)

The present invention is directed toward a method of removing epitaxial substrates from host substrates. A sacrificial release layer of ternary material is placed on the substrate. A layer of InP is then placed on the ternary material. Afterward a layer of wax is applied to the InP layer to apply compressive force and an etchant material is used to remove the sacrificial release layer.

Bailey, Sheila G. (Inventor); Wilt, David M. (Inventor); DeAngelo, Frank L. (Inventor)

1997-01-01

54

Building biomedical materials layer-by-layer  

Directory of Open Access Journals (Sweden)

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.

Paula T. Hammond

2012-05-01

55

Treatment of colloidal waste material by electroflotation using sacrificial electrodes. Gisei denkyoku wo mochiita denkai fujo bunri ni yoru colloid jo kendaku busshitsu no shori  

Energy Technology Data Exchange (ETDEWEB)

Experiments were carried out on batch electroflotation using aluminum sacrificial electrodes for such a colloidal waste material as disperse dye. The experiments were intended to elucidate separation mechanisms and look into various conditions to maximize separation rate. The following results were obtained: Aluminum dissolution is proportional to current density and is larger than the theoretical value based on Faraday's law; the separation process consists of two steps; in the first step the sol concentration remained nearly at the initial value, and flocculation of the sol is based on a charge neutralization with dissolved aluminum ions; the second step is a flotation and separation process in which the separation followed a linear velocity expression and the velocity constant increased with increasing current densities; the aluminum dissolution can be increased effectively with use of a polarity conversion method to switch anodic and cathodic polarities every certain times, where the optimum conversion time was found to be about 900 seconds; and use of bipolar electrodes disposed with auxiliary electrodes was effective to optimize the operation voltage and reduce the size of flotation tanks. 11 refs., 14 figs.

Osasa, K.; Nakakura, H.; Tanaka, H. (Yamaguchi Univ., Yamaguchi (Japan). Faculty of Engineering)

1993-03-10

56

CMP Control of Multi-Layer Inter-Layer Dielectrics (ILD) using X-ray Reflectivity  

International Nuclear Information System (INIS)

Thin sacrificial films are used as cap layer in the back-end semiconductor processing for protecting the bulk porous inter-layer low-k dielectric during the CMP process. The existing optical measurement techniques struggle to separate these thin films from the bulk low-k due to very similar optical coefficients. Glancing angle x-ray reflectivity is well suited for separation of thin sacrificial film and bulk dielectric film as x-ray reflectivity depends strongly on changes in electron densities for two materials. This paper discusses the x-ray reflectivity technique and its applications for measurement of low-k stack and sacrificial oxide post CMP

57

Thick photopolymer layers for holographic recording materials  

OpenAIRE

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

Garci?a Llopis, Celia; Fimia Gil, Antonio; Pascual Villalobos, Inmaculada

1999-01-01

58

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

59

KAPOOL experiments to simulate molten corium - sacrificial concrete interaction  

International Nuclear Information System (INIS)

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

60

Innovative design and material solutions of thermal contact layers for high heat flux applications in fusion devices  

International Nuclear Information System (INIS)

One difficulty associated with the design and development of sacrificial plasma facing components that have to handle the high heat and particle fluxes in ITER is achieving the necessary contact conductance between the plasma protection material and the high-conductivity substrate in contact with the coolant. This paper presents a novel bond idea which is proposed as one of the options for the sacrificial energy dump targets located at the bottom of the divertor legs. The bonded joint in this design concept provides thermal and electrical contact between the armour and the cooled sub-structure while promoting remote, in-situ maintenance repair and an easy replaceability of the armour part without disturbing the cooling pipes or rewelding neutron irradiated materials. To provide reliable and demountable adhesion, the bond consists of a metal alloy, treated in the semi-solid phase so that it leads to a fine dispersion of a globular solid phase into a liquid matrix (rheocast process). This thermal bond layer would normally operate in the solid state but could be brought reversibly to the semi-solid state during the armour replacement simply by heating it slightly above its solidus temperature. Material and design options are discussed in this paper. Possible methods of installation and removal are described, and lifetime considerations are addressed. In order to validate this concept within the ITER time-frame, a R ampersand D programme must be rapidly implementedogramme must be rapidly implemented

61

Layer coefficients for NHDOT pavement materials  

Science.gov (United States)

In 1992, the New Hampshire Department of Transportation (NHDOT) experimented with the use of reclaimed asphalt concrete as a base course material, identified by NHDOT as reclaimed stabilized base (RSB). The RSB and a control test section were placed on Interstate 93 between exits 18 and 19. The RSB test section was designed to the same structural number (SN) as the control. To evaluate the structural capacity of these test sections, the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) conducted deflection tests using a Dynatest 8000 falling weight deflectometer (FWD). Preliminary analysis of the results by NHDOT personnel showed higher deflection in the reclaimed asphalt concrete test sections. The explanation was that the layer coefficient used for the RSB layer in the design was probably incorrect. A total of 10 test sections constituting the base course materials used by NHDOT were built near Bow, New Hampshire. CRREL evaluated and estimated the layer coefficients of the base course materials. The test program was developed to characterize the material in more than one way. Tests were conducted with the heavy weight deflectometer (HWD), dynamic cone penetrometer (DCP) and the Clegg hammer. In situ California bearing ratio (CBR) tests were also conducted. The deflection from the HWD were used with the WESDEF back calculation program to determine the layer moduli. The moduli were than used with the AASHTO Design Guide to calculate the layer coefficients. The layer coefficients were also determined with the method proposed by Rohde. The CBR values from the Clegg hammer, in situ CBR and DCP tests were also used in the relationships in the HDM model to determine the layer coefficients.

Janoo, Vincent C.

1994-09-01

62

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)

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.

J?nis Lejnieks

2010-05-01

63

Layered zeolite materials and methods related thereto  

Science.gov (United States)

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.

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

2013-08-06

64

Harmonic generation in 2D layered materials  

Science.gov (United States)

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 .

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

2014-09-01

65

Eroded Layered Material in Southwest Utopia Planitia  

Science.gov (United States)

Images from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)dramatically illustrate that many places on the red planet have outcrops of layered geologic materials. The two pictures above show the remains of layered material inside craters in southwestern Utopia Planitia (see inset for detailed view). These remnant layers indicate that the craters--and perhaps the plains that surround them--were once buried beneath a deposit that has since been eroded away. This theme of layered outcrops and exhumed craters appears to be one of the dominant observations that MGS MOC has made--to date--about Mars. The origin and composition of the layered material--and its ultimate fate once it was largely eroded away--are unknown. Each of the two pictures shown here covers an area about 4 kilometers (2.5 miles)by 6.3 kilometers (3.9 miles). Illumination is from the lower right. These are subframes of a single MOC image acquired in July 1998 during the MGS Science Phasing Orbits imaging campaign. This figure was presented at the 30th Lunar and Planetary Science Conference in Houston, Texas, March 1999. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1999-01-01

66

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).

67

Sacrificial Plastic Mold With Electroplatable Base  

Science.gov (United States)

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.

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

2005-08-16

68

Atomic layer deposition of metal sulfide materials.  

Science.gov (United States)

Conspectus The field of nanoscience is delivering increasingly intricate yet elegant geometric structures incorporating an ever-expanding palette of materials. Atomic layer deposition (ALD) is a powerful driver of this field, providing exceptionally conformal coatings spanning the periodic table and atomic-scale precision independent of substrate geometry. This versatility is intrinsic to ALD and results from sequential and self-limiting surface reactions. This characteristic facilitates digital synthesis, in which the film grows linearly with the number of reaction cycles. While the majority of ALD processes identified to date produce metal oxides, novel applications in areas such as energy storage, catalysis, and nanophotonics are motivating interest in sulfide materials. Recent progress in ALD of sulfides has expanded the diversity of accessible materials as well as a more complete understanding of the unique chalcogenide surface chemistry. ALD of sulfide materials typically uses metalorganic precursors and hydrogen sulfide (H2S). As in oxide ALD, the precursor chemistry is critical to controlling both the film growth and properties including roughness, crystallinity, and impurity levels. By modification of the precursor sequence, multicomponent sulfides have been deposited, although challenges remain because of the higher propensity for cation exchange reactions, greater diffusion rates, and unintentional annealing of this more labile class of materials. A deeper understanding of these surface chemical reactions has been achieved through a combination of in situ studies and quantum-chemical calculations. As this understanding matures, so does our ability to deterministically tailor film properties to new applications and more sophisticated devices. This Account highlights the attributes of ALD chemistry that are unique to metal sulfides and surveys recent applications of these materials in photovoltaics, energy storage, and photonics. Within each application space, the benefits and challenges of novel ALD processes are emphasized and common trends are summarized. We conclude with a perspective on potential future directions for metal chalcogenide ALD as well as untapped opportunities. Finally, we consider challenges that must be addressed prior to implementing ALD metal sulfides into future device architectures. PMID:25581295

Dasgupta, Neil P; Meng, Xiangbo; Elam, Jeffrey W; Martinson, Alex B F

2015-02-17

69

Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films  

Science.gov (United States)

Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

Hankins, Matthew G. (Albuquerque, NM)

2009-10-06

70

Assessing Layered Materials in Gale Crater  

Science.gov (United States)

The recent analysis of high resolution Mars Orbiter Camera (MOC) images of layered outcrops in equatorial regions reinforces two important ideas, which will probably eventually become paradigms, about Mars: 1) It has had a long, complex geologic history marked by change, as manifested in the different layers observed, and 2) Standing bodies of water existed for substantial lengths of time, indicating clement conditions possibly conducive to life. Although observations of layering and evidence for lakes and oceans has been reported for years based on Mariner 9 and Viking data, the MOC data show that this layering is much more pervasive and complex than previously thought. These layered sites are ideal for studying the geologic, and possibly biologic, history of Mars. Here, a layered site within Gale Crater is advocated as a Mars Exploration Rover (MER) target. This is one of the few layered areas within closed depressions (e.g., other craters and Vallis Marineris) that meets the landing site constraints and is accessible to both MER A and B.

Bridges, N. T.

2001-01-01

71

Alternating Current Corrosion of Aluminium Sacrificial Anodes  

OpenAIRE

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...

Forthun, Kari

2013-01-01

72

Atomic layer deposition of nanostructured materials  

CERN Document Server

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

Pinna, Nicola

2012-01-01

73

Quantifying the Stacking Registry Matching in Layered Materials  

CERN Document Server

A detailed account of a recently developed method [Marom et al., Phys. Rev. Lett. 105, 046801 (2010)] to quantify the registry mismatch in layered materials is presented. The registry index, which was originally defined for planar hexagonal boron-nitride, is extended to treat graphitic systems and generalized to describe multi-layered nanotubes. It is shown that using simple geometric considerations it is possible to capture the complex physical features of interlayer sliding in layered materials. The intuitive nature of the presented model and the efficiency of the related computations suggest that the method can be used as a powerful characterization tool for interlayer interactions in complex layered systems.

Hod, Oded

2010-01-01

74

Novel composite materials synthesized by the high-temperature interaction of pyrrole with layered oxide matrices  

Science.gov (United States)

The initial goal of the research presented herein was to develop the very first synthetic metal---high-temperature superconductor ceramic composite material, in the specific form of a polypyrrole---Bi2Sr2CaCu 2O8+delta nanocomposite. In the course of scientific investigation, this scope was broadened to encompass structurally and compositionally similar layered bismuthates and simpler layered oxides. The latter substrates were prepared through novel experimental procedures that enhanced the chance of yielding nanostructured morphologies. The designed novel synthesis approaches yielded a harvest of interesting results that may be further developed upon their dissemination in the scientific community. High-temperature interaction of pyrrole with molybdenum trioxide substrates with different crystalline phases and morphologies led to the formation of the first members of a new class of heterogeneous microcomposites characterized by incomplete occupancy by the metal oxide core of the volume encapsulated by the rigid, amorphous permeable polymeric membrane that reproduces the volume of the initial grain of precursor substrate. The method may be applied for various heterogeneous catalyst substrates for the precise determination of the catalytically active crystallographic planes. In a different project, room-temperature, templateless impregnation of molybdenum trioxide substrates with different crystalline phases and morphologies by a large excess of silver (I) cations led to the formation of 1-D nanostructured novel Ag-Mo-O ternary phase in what may be the simplest experimental procedure available to date that has yielded a 1-D nanostructure, regardless the nature of the constituent material. Interaction of this novel ternary phase with pyrrole vapors at high reaction temperatures led to heterogeneous nanostructured composites that exhibited a silver nanorod core. Nanoscrolls of vanadium pentoxide xerogel were synthesized through a novel, facile reflux-based method that employed very acidic pH levels and long reaction times. The nanoscrolls proved to be an excellent precursor for the synthesis of reduced vanadium oxide nanosheets by the redox intercalation of long chain monoamine molecules. In a related development, the very first synthetic metal---mixed-valence polyoxovanadate salt hybrid material was synthesized in the form of a polypyrrole---tetrammonium hexavanadate microcomposite by a redox simultaneous co-precipitation in an aqueous solution. The novel material displayed good mechanical properties towards solid lubricant applications and tunable electronic conductivity. Nanocomposites of polypyrrole---layered bismuthates were produced by the topotactic intercalation of pyrrole and its subsequent in situ polymerization. Insulating and superconducting layered bismuthates were used in a similar experimental procedure that used pre-intercalated iodine species as sacrificial topotactic oxidizing agents. A novel method of iodine intercalation by a solution-based transport procedure was used in the process. Interaction of pyrrole with layered bismuthates at high reaction temperatures led to the formation of polymer-covered metal nanorods as a result of intrinsic lattice templating effect. The successful synthesis of the 1-D heterogeneous nanostructures represents the first example in which nanocomposites were used as precursors. Appropriate doping of the initial layered ceramic substrates led to polymer-covered metal alloy nanorods.

Pavel, Alexandru Cezar

75

Mechanics of freely-suspended ultrathin layered materials  

OpenAIRE

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 mat...

Castellanos-gomez, Andres; Singh, Vibhor; Zant, Herre S. J.; Steele, Gary A.

2014-01-01

76

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

Science.gov (United States)

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.

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

2015-02-01

77

Method for depositing layers of high quality semiconductor material  

Science.gov (United States)

Plasma deposition of substantially amorphous semiconductor materials is carried out under a set of deposition parameters which are selected so that the process operates near the amorphous/microcrystalline threshold. This threshold varies as a function of the thickness of the depositing semiconductor layer; and, deposition parameters, such as diluent gas concentrations, must be adjusted as a function of layer thickness. Also, this threshold varies as a function of the composition of the depositing layer, and in those instances where the layer composition is profiled throughout its thickness, deposition parameters must be adjusted accordingly so as to maintain the amorphous/microcrystalline threshold.

Guha, Subhendu (Troy, MI); Yang, Chi C. (Troy, MI)

2001-08-14

78

Layered zeolitic materials: an approach to designing versatile functional solids.  

Science.gov (United States)

Relevant layered zeolites have been considered in this perspective article from the point of view of the synthesis methodologies, materials characterization and catalytic implications, considering the unique physico-chemical characteristics of lamellar materials. The potential of layered zeolitic precursors to generate novel lamellar accessible zeolites through swelling, intercalation, pillarization, delamination and/or exfoliation treatments is studied, showing the chemical, functional and structural versatility exhibited by layered zeolites. Recent approaches based on the assembly of zeolitic nanosheets which act as inorganic structural units through the use of dual structural directing agents, the selective modification of germanosilicates and the direct generation of lamellar hybrid organic-inorganic aluminosilicates are also considered to obtain layered solids with well-defined functionalities. The catalytic applications of the layered zeolites are also highlighted, pointing out the high accessibility and reactivity of active sites present in the lamellar framework. PMID:24457617

Díaz, Urbano; Corma, Avelino

2014-07-21

79

Tailoring nanoporous materials by atomic layer deposition.  

Science.gov (United States)

Atomic layer deposition (ALD) is a cyclic process which relies on sequential self-terminating reactions between gas phase precursor molecules and a solid surface. The self-limiting nature of the chemical reactions ensures precise film thickness control and excellent step coverage, even on 3D structures with large aspect ratios. At present, ALD is mainly used in the microelectronics industry, e.g. for growing gate oxides. The excellent conformality that can be achieved with ALD also renders it a promising candidate for coating porous structures, e.g. for functionalization of large surface area substrates for catalysis, fuel cells, batteries, supercapacitors, filtration devices, sensors, membranes etc. This tutorial review focuses on the application of ALD for catalyst design. Examples are discussed where ALD of TiO(2) is used for tailoring the interior surface of nanoporous films with pore sizes of 4-6 nm, resulting in photocatalytic activity. In still narrower pores, the ability to deposit chemical elements can be exploited to generate catalytic sites. In zeolites, ALD of aluminium species enables the generation of acid catalytic activity. PMID:21695333

Detavernier, Christophe; Dendooven, Jolien; Sree, Sreeprasanth Pulinthanathu; Ludwig, Karl F; Martens, Johan A

2011-11-01

80

Incorporating microorganisms into polymer layers provides bioinspired functional living materials  

OpenAIRE

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...

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

2011-01-01

81

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)

82

Interlayer commensurability and superlubricity in rigid layered materials  

Science.gov (United States)

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

Hod, Oded

2012-08-01

83

Mechanics of freely-suspended ultrathin layered materials  

International Nuclear Information System (INIS)

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)

84

Mechanics of freely-suspended ultrathin layered materials  

Energy Technology Data Exchange (ETDEWEB)

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)

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

85

Electronic transport properties of few-layer graphene materials  

OpenAIRE

Since the discovery of graphene -a single layer of carbon atoms arranged in a honeycomb lattice - it was clear that this truly is a unique material system with an unprecedented combination of physical properties. Graphene is the thinnest membrane present in nature -just one atom thick- it is the strongest material, it is transparent and it is a very good conductor with room temperature charge mobilities larger than the typical mobilities found in silicon. The significance pl...

Russo, S.; Craciun, M. F.; Khodkov, T.; Koshino, M.; Yamamoto, M.; Tarucha, S.

2011-01-01

86

CVD COATING OF CERAMIC LAYERS ON CERAMIC CUTTING TOOL MATERIALS  

OpenAIRE

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...

Porat, R.

1991-01-01

87

The effect of gamma irradiation on few layered graphene materials  

OpenAIRE

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...

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

88

Resistance to forced airflow through layers of composting organic material.  

Science.gov (United States)

The objective of this study was to adjust equations to estimate the static pressure gradient of airflow through layers of organic residues submitted to two stages of biochemical degradation, and to evaluate the static pressure drop of airflow thought the material layer. Measurements of static pressure drop in the layers of sugarcane bagasse and coffee husks mixed with poultry litter on day 0 and after 30 days of composting were performed using a prototype with specific airflow rates ranging from 0.02 to 0.13 m(3) s(-1) m(-2). Static pressure gradient and specific airflow rate data were properly fit to the Shedd, Hukill & Ives and Ergun models, which may be used to predict the static pressure gradient of air to be blown through the organic residue layers. However, the Shedd model was that which best represented the phenomenon studied. The static pressure drop of airflow increased as a power of the material layer thickness and showed tendency for decreasing with the biochemical degradation time of the organic material. PMID:25536861

Teixeira, Denis Leocádio; de Matos, Antonio Teixeira; Melo, Evandro de Castro

2015-02-01

89

Nanoindentation of near-surface layers of materials  

International Nuclear Information System (INIS)

With the help of nanoindenter G200 zirconium, copper and chrome near-surface layer nanohardness was studied. It is shown, that stable value of nanohardness can be obtained only from depth below 500 nm depending on investigated material surface condition.

90

Carbon and titanium based layers for wood-based material  

Directory of Open Access Journals (Sweden)

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.

W. Kaczorowski

2008-04-01

91

A study of layered lithium manganese oxide cathode materials  

Science.gov (United States)

Substituted layered sodium manganese oxide bronzes with the P2 structure were prepared by glycine-nitrate combustion synthesis. The Na in the as-prepared materials could be completely ion-exchanged for Li under mild conditions. All lithium manganese oxide compounds obtained after ion-exchange have O2 stacking of the layers. Cyclic voltammetry and stepped potential experiments on lithium cells containing these materials show that the main redox reaction around 3.1 V is a diffusion-controlled process and is completely reversible. O2-Li 0.6[Al 0.1Mn 0.85? 0.05]O 2 and O2-Li 0.6[Ni 0.1Mn 0.85? 0.05]O 2 are particularly promising as cathode materials in lithium cells because of the high reversible discharge capacities (180 mAh/g).

Eriksson, Tom A.; Doeff, Marca M.

92

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

Science.gov (United States)

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

Gelber, Matthew K; Bhargava, Rohit

2015-03-17

93

The possibility of forming a sacrificial anode coating for Mg  

Energy Technology Data Exchange (ETDEWEB)

Mg is the most active engineering metal, and is often used as a sacrificial anode/coating to protect other engineering metals from corrosion attack. So far no sacrificial anode coating has been developed or considered for Mg. This study explores the possibility of forming a sacrificial coating for Mg. A lithiated carbon coating and a metaphosphated coating are applied on the Mg surface, respectively, and their open-circuit-potentials are measured in saturated Mg(OH)2 solution. They exhibit more negative potentials than bare Mg. SEM reveals that the metaphosphated coating offers more effective and uniform protection for Mg than the lithiated carbon coating. These preliminary results indicate that development of a sacrificial anode coating for Mg is indeed possible.

Dudney, Nancy J [ORNL; Li, Juchuan [Oak Ridge National Laboratory (ORNL); Sacci, Robert L [ORNL; Thomson, Jeffery K [ORNL

2014-01-01

94

From Eshu to Obatala: animals used in sacrificial rituals at Candomblé "terreiros" in Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The practice of sacrifice has occurred in several cultures and religions throughout history and still exists today. Candomblé, a syncretical Afro-Brazilian religion, practices the sacrificial ritual called "Orô" by its adherents. The present work aims to document the use of animal species in these sacrificial practices in the cities of Caruaru (PE and Campina Grande (PB in Norteastern Brazil, and to further understand the symbolism of these rituals. Methods Semi-structured and unstructured interviews and informal discussions were held with 11 Candomblé priests and priestesses between the months of August 2007 and June 2008. We attended rituals performed at "terreiros" where animals were sacrificed, in order to obtain photographic material and observe the procedures and techniques adopted. Results A total of 29 animal species were used during sacrificial rituals according to the priests and priestesses. These species were classified in 5 taxanomic groups: Molluscs (n = 1, Amphibians (n = 2, Reptiles (n = 2, Birds (n = 10 and Mammals (n = 14. According to Candomblé beliefs, animals are sacrificed and offered to their deities, known as orishas, for the prosperity of all life. There is a relationship between the colour, sex and behaviour of the animal to be sacrificed, and the orisha to whom the animal is going to be offered. The many myths that form the cosmogony of Candomblé can often explain the symbolism of the rituals observed and the animal species sacrificed. These myths are conveyed to adherants by the priests and priestesses during the ceremonies, and are essential to the continuation of this religion. Conclusion Candomblé is a sacrificial religion that uses animals for its liturgical purposes. The principal reason for sacrifice is to please supernatural deities known as orishas in order to keep life in harmony. This is accomplished through feeding them in a spiritual sense through sacrifice, maintaining a perfect link between men and the gods, and a connection between the material world (called Aiyê and the supernatural world (called Orun.

Brooks Sharon E

2009-08-01

95

Nanoscale layered double hydroxide materials for corrosion resistance  

OpenAIRE

Layered Double Hydroxides (LDH?s), represented by the general formula [MII (1-x)MIIIx(OH)2[An-x/n].zH2O or [MIMIII2(OH)6[An-1/n].zH2O], where MI, MII, MIII are mono-, di- and tri-valent metal cations, are being researched as anion-exchange materials which interesting intercalation chemistry that accommodate a wide range of applications from heterogeneous catalysis to storage and subsequent controlled release of bioactive agents. In this work, layered double hydroxides containing a monovalen...

Rangel, C. M.; Travassos, Maria Anto?nia

2007-01-01

96

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

97

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2013-10-22

98

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2014-09-16

99

Ultralight Weight Optical Systems Using Nano-Layered Synthesized Materials  

Science.gov (United States)

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

Clark, Natalie; Breckinridge, James

2014-01-01

100

Atomic Layer Deposition for the Conformal Coating of Nanoporous Materials  

Directory of Open Access Journals (Sweden)

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.

Joe H. Satcher

2006-07-01

101

Atomic layer deposited aluminum oxide barrier coatings for packaging materials  

Energy Technology Data Exchange (ETDEWEB)

Thin aluminum oxide coatings have been deposited at a low temperature of 80 {sup o}C on various uncoated papers, polymer-coated papers and boards and plain polymer films using the atomic layer deposition (ALD) technique. The work demonstrates that such ALD-grown Al{sub 2}O{sub 3} coatings efficiently enhance the gas-diffusion barrier performance of the studied porous and non-porous materials towards oxygen, water vapor and aromas.

Hirvikorpi, Terhi, E-mail: terhi.hirvikorpi@vtt.f [Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), P.O. Box 70, FI-02151 Espoo (Finland); Vaehae-Nissi, Mika, E-mail: mika.vaha-nissi@vtt.f [Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), P.O. Box 70, FI-02151 Espoo (Finland); Mustonen, Tuomas, E-mail: tuomas.mustonen@vtt.f [Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), P.O. Box 70, FI-02151 Espoo (Finland); Iiskola, Eero, E-mail: eero.iiskola@kcl.f [Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), P.O. Box 70, FI-02151 Espoo (Finland); Karppinen, Maarit, E-mail: maarit.karppinen@tkk.f [Laboratory of Inorganic Chemistry, Department of Chemistry, Helsinki University of Technology, P.O. Box 6100, FI-02015 TKK (Finland)

2010-03-01

102

Study of materials for using at waste layer in repositories  

International Nuclear Information System (INIS)

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

103

Sacrificial bonds in stacked-cup carbon nanofibers: biomimetic toughening mechanisms for composite systems.  

Science.gov (United States)

Many natural composites, such as nacre or bone, achieve exceptional toughening enhancements through the rupture of noncovalent secondary bonds between chain segments in the organic phase. This "sacrificial bond" rupture dissipates enormous amounts of energy and reveals significant hidden lengths due to unraveling of the highly coiled macromolecules, leaving the structural integrity of their covalent backbones intact to large extensions. In this work, we present the first evidence of similar sacrificial bond mechanisms in the inorganic phase of composites using inexpensive stacked-cup carbon nanofibers (CNF), which are composed of helically coiled graphene sheets with graphitic spacing between adjacent layers. These CNFs are dispersed in a series of high-performance epoxy systems containing trifunctional and tetrafunctional resins, which are traditionally difficult to toughen in light of their highly cross-linked networks. Nonetheless, the addition of only 0.68 wt % CNF yields toughness enhancements of 43-112% for the various blends. Analysis of the relevant toughening mechanisms reveals two heretofore unseen mechanisms using sacrificial bonds that complement the observed crack deflection, rupture, and debonding/pullout that are common to many composite systems. First, embedded nanofibers can splay discretely between adjacent graphitic layers in the side walls; second, crack-bridging nanofibers can unravel continuously. Both of these mechanisms entail the dissipation of the pi-pi interactions between layers in the side walls without compromising the structural integrity of the graphene sheets. Moreover, increases in electrical conductivity of approximately 7-10 orders of magnitude were found, highlighting the multifunctionality of CNFs as reinforcements for the design of tough, inexpensive nanocomposites with improved electrical properties. PMID:20568708

Palmeri, Marc J; Putz, Karl W; Brinson, L Catherine

2010-07-27

104

Sacrificial template method of fabricating a nanotube  

Science.gov (United States)

Methods of fabricating uniform nanotubes are described in which nanotubes were synthesized as sheaths over nanowire templates, such as using a chemical vapor deposition process. For example, single-crystalline zinc oxide (ZnO) nanowires are utilized as templates over which gallium nitride (GaN) is epitaxially grown. The ZnO templates are then removed, such as by thermal reduction and evaporation. The completed single-crystalline GaN nanotubes preferably have inner diameters ranging from 30 nm to 200 nm, and wall thicknesses between 5 and 50 nm. Transmission electron microscopy studies show that the resultant nanotubes are single-crystalline with a wurtzite structure, and are oriented along the direction. The present invention exemplifies single-crystalline nanotubes of materials with a non-layered crystal structure. Similar "epitaxial-casting" approaches could be used to produce arrays and single-crystalline nanotubes of other solid materials and semiconductors. Furthermore, the fabrication of multi-sheath nanotubes are described as well as nanotubes having multiple longitudinal segments.

Yang, Peidong (Berkeley, CA); He, Rongrui (Berkeley, CA); Goldberger, Joshua (Berkeley, CA); Fan, Rong (El Cerrito, CA); Wu, Yi-Ying (Albany, CA); Li, Deyu (Albany, CA); Majumdar, Arun (Orinda, CA)

2007-05-01

105

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

CERN Document Server

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 ...

Beer, Albert C; Pearsall, Thomas P

1991-01-01

106

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

Science.gov (United States)

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

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

2015-01-01

107

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

Science.gov (United States)

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.

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

2014-01-01

108

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

Directory of Open Access Journals (Sweden)

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.??????? ???????????? ????????????????? ?????????? ?????? ? ???????????? ????????????? ?????????? ???????????????? ????????? ????????, ? ????????? ????????? ???????. ??????????? ???? ?????? ?????????? ? ???????? ?? ???? ?????????? ??????????? ??????????????? ?????????, ? ?.?. ???????? ???????? ????????? ???? ???????. ? ??????????? ?????????????? ??????? ???????? ?????????? ?? ??????? ?????????? ???????? ????????? ???????????? ??????? ? ??? ???????? ?????????. ??????????? ???? ????????? ????????? ????????? ????????????? ?????????????? ???????.

Zhukov Aleksey Dmitrievich

2013-05-01

109

Nanoscale engineering materials by supercritical fluid and atomic layer deposition  

Science.gov (United States)

With the development of material science and technology, modification of substrates, which have random geometry and high aspect ratio three dimensional (3D) complex structures, with desired functional, reactive and stable coatings becomes important and challenging. The ability to fabricate mono- or multi-layers of functional materials with precisely controlled dimensions, finely tuned composition and molecular structures, attracts significant interests in materials science and is the key to construct such devices and structures at nano- and micro-scale with desired properties. In this study, supercritical carbon dioxide (scCO2) has been studied as an alternative route for modifying substrates due to the unique gas-like (low viscosity, high diffusivity and zero surface tension) and liquid-like properties (high density). (1) The reaction kinetics of metal oxides thin film deposition from pyrolysis of metal organics in scCO2 was studied in detail. This method was demonstrated as a powerful technique to coat oxides, including Al2O3, Ga2O3 and others, into 3D high aspect ratio complex structure of carbon nanotubes (CNTs) forest. (2) The low temperature scCO 2 based hydrogenolysis process was developed as a useful way to functionalize aligned CNTs forest with dense Nickel nanoparticles. On the second part of this work, atomic layer deposition (ALD)/molecular layer deposition (MLD), as a vapor phase, stepwise and self-limiting vacuum based deposition process, was demonstrated as a powerful way to form highly conformal and uniform film onto substrates, even into highly complex 3D complex structures. In this study, (4) Metal oxide ALD is applied onto 3D electrospun polymer microfiber mats template to illustrate an effective and robust strategy to fabricate long and uniform metal oxide microtubes with precisely controllable wall thickness. Designer tubes of various sizes and different materials were demonstrated by using this method. (5) By further extending this technique, complex coaxial Al2O3/ZnO/Al2O3 multilayed microtubular structure is fabricated, which provides an unique platform to study the solid state reaction and diffusion process (Kirkendall Effect) between Al2 O3 shells and the confined middle ZnO layers by annealing the samples at 700°C. (6) The extension of ALD-MLD process of polyamides, zinc hybrid, aminosilane self assembly monolayers were studied by various techniques to illustrate the surface reaction mechanism.

Peng, Qing

110

Encapsulation of the herbicide picloram by using polyelectrolyte biopolymers as layer-by-layer materials.  

Science.gov (United States)

Microcapsules of the herbicide picloram (PLR) were formulated by a layer-by-layer (LbL) self-assembly method using the polyelectrolyte biopolymers of biocompatible chitosan (CS) and the UV-absorbent sodium lignosulfonate (SL) as shell materials. The herbicide PLR was recrystallized and characterized using XRD analysis. The obtained PLR-loaded microcapsules were characterized by using SEM, FTIR, CLSM, and ?-potential measurements. The herbicide loading and encapsulation efficiency were also analyzed for the PLR-loaded microcapsules. The influence of LbL layer numbers on herbicide release and photodegradation rates was investigated in vitro. The results showed that the release rates and photodegradation rates of PLR in microcapsules decreased with increasing number of CS/SL self-assembly layers. The results demonstrated that polyelectrolyte biopolymer-based LbL multilayer microcapsules can be a promising approach for the controlled release of PLR as well as other pesticides with poor photostability or short half-release time. PMID:23544987

Wang, Xiaojing; Zhao, Jing

2013-04-24

111

Utilization of Industrial Waste Material in GSB Layer  

Directory of Open Access Journals (Sweden)

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.

U Arun Kumar

2014-08-01

112

Physico-chemical and material aspects of the core melt retention concept of the EPR  

International Nuclear Information System (INIS)

To maintain containment integrity and to reduce the radiological consequences of a postulated severe accident, the core melt stabilization concept of the EPR employs sacrificial materials for melt conditioning and protective materials to avoid basemat penetration. The sacrificial materials added to the core melt fully oxidize the chemically aggressive metallic zirconium, significantly reduce the initially very high melt temperature and lead to a favorable layer inversion in the spreading room. Experimental and theoretical work shows that the sacrificial concrete lowers the liquidus temperature of the oxidic corium melt down to 1800-1850 C. This in turn reduces the long-term temperatures of the molten corium and hence also the thermochemical challenges to the protective layer in the spreading room. The spreading area consists of three layers of different materials (from top to bottom): (i) sacrificial concrete, (ii) sacrificial metal and (iii) zirconia (ZrO2) as protective material. Due to the layer inversion achieved by the sacrificial material a contact between the oxidic melt and the protective layer with corresponding thermochemical interactions is avoided. The protective material is in contact with a metal melt (Fe, 3-7 w% Cr, 7 w% Ni). This metal melt is covered by a less dense oxidic melt (UO2, ZrO2, FeO, SiO2, Al2O3, CaO,..) which gives rise to a certain oxygen concentration in the metal melt. Thoxygen concentration in the metal melt. The thermochemical stability of ZrO2 is predominantly influenced by the temperature and oxygen concentration in the metallic melt. The parameter governing the stability against chemical dissolution is the activity of FeO in the metal melt which is related to the oxygen concentration. Performed theoretical and experimental investigations demonstrate that under EPR conditions this FeO activity always remains below the threshold value for the formation of liquid ZrO2-FeO phases and therefore dissolution of ZrO2 can be excluded. The presence of the weak desoxidant chromium in the metallic melt is beneficial and further increases the safety margin compared to a chromium-free metal melt. Technological application forms of ZrO2 are sinteractive ramming mass, sintered ceramic bricks or ZrO2 concretes. At the current state of knowledge, ramming mass is the most promising application form for the bottom area of the spreading room. Laboratory tests have shown that, when heating ramming mass by a metallic melt under

113

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)

114

Advanced Lithium Ion Battery Materials Prepared with Atomic Layer Deposition  

Science.gov (United States)

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

Cavanagh, Andrew S.

115

Highly efficient gate-tunable photocurrent generation in vertical heterostructures of layered materials  

OpenAIRE

Layered materials of graphene and MoS2, for example, have recently emerged as an exciting material system for future electronics and optoelectronics. Vertical integration of layered materials can enable the design of novel electronic and photonic devices. Here, we report highly efficient photocurrent generation from vertical heterostructures of layered materials. We show that vertically stacked graphene–MoS2–graphene and graphene–MoS2–metal junctions can be created with a broad juncti...

Yu, Woo Jong; Liu, Yuan; Zhou, Hailong; Yin, Anxiang; Li, Zheng; Huang, Yu; Duan, Xiangfeng

2013-01-01

116

An innovative series of layered nanostructured aminoalkylsilica hybrid material  

Scientific Electronic Library Online (English)

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

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

117

Large-scale simulations of layered double hydroxide nanocomposite materials  

Science.gov (United States)

Layered double hydroxides (LDHs) have the ability to intercalate a multitude of anionic species. Atomistic simulation techniques such as molecular dynamics have provided considerable insight into the behaviour of these materials. We review these techniques and recent algorithmic advances which considerably improve the performance of MD applications. In particular, we discuss how the advent of high performance computing and computational grids has allowed us to explore large scale models with considerable ease. Our simulations have been heavily reliant on computational resources on the UK's NGS (National Grid Service), the US TeraGrid and the Distributed European Infrastructure for Supercomputing Applications (DEISA). In order to utilise computational grids we rely on grid middleware to launch, computationally steer and visualise our simulations. We have integrated the RealityGrid steering library into the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) 1 . which has enabled us to perform re mote computational steering and visualisation of molecular dynamics simulations on grid infrastruc tures. We also use the Application Hosting Environment (AHE) 2 in order to launch simulations on remote supercomputing resources and we show that data transfer rates between local clusters and super- computing resources can be considerably enhanced by using optically switched networks. We perform large scale molecular dynamics simulations of MgiAl-LDHs intercalated with either chloride ions or a mixture of DNA and chloride ions. The systems exhibit undulatory modes, which are suppressed in smaller scale simulations, caused by the collective thermal motion of atoms in the LDH layers. Thermal undulations provide elastic properties of the system including the bending modulus, Young's moduli and Poisson's ratios. To explore the interaction between LDHs and DNA. we use molecular dynamics techniques to per form simulations of double stranded, linear and plasmid DNA up to 480 base pairs in length intercalated within LDHs. Our models are found to be in agreement with experimental observations, according to which hydration is a crucial factor in determining the structural stability of DNA. At elevated tem peratures and pressures, the structural stability of LDH-intercalated DNA is substantially enhanced as compared to DNA in bulk water. We also discuss how the properties of LDHs are modified due to DNA intercalation. Our studies show that LDHs are flexible enough to deform around bulky intercalants such as DNA. The flexibility of layered materials has been shown to affect the pathway by which intercalation occurs. Recent experimental studies of LDHs have shown that these minerals can form staged intermediate structures during intercalation. However, the mechanism which produces staged structures remains un determined. We simulated three differently stacked structures and show that even though the structures under study are all energetically very similar, overall there is greater diffusion of DNA strands in a Daumas-Herold configuration compared to a Rudorff model and a stage-1 structure. The picture on the titlepage was produced using a visualisation package called Visual Molecular Dy namics (VMD) and represents a plasmid strand of DNA containing 480 base pairs intercalated inside an LDH. Only one layer of the LDH is displayed and water molecules have been hidden in order to aid viewing of the structure. The visualisation was produced from our largest simulation which contained 1,157,038 atoms, with lateral dimensions of 588.3Ax677.7A.

Thyveetil, Mary-Ann

118

Film growth of C59N on layered materials  

Science.gov (United States)

C59N was evaporated in an UHV system onto substrates of the layered materials HOPG, WSe2 and mica at substrate temperatures of 25 °C, 100 °C and 200 °C. The initial growth of the C59N films was investigated by atomic force microscopy (UHV-AFM) and compared to that of C60. Distinct island sizes and shapes were observed for the three substrates, reflecting different mobilities and sticking factors. For C59N on HOPG and WSe2, extended dendritic islands are formed indicating a large mobility of C59N on the substrate and a strong sticking of the molecules to the islands edges. The mobility during the growth of the second monolayer is significantly reduced therefore, nearly independent of the substrate temperature, many new nucleation centres with distances as small as 50 nm are formed on top of the 1000-3000 nm monolayer islands. On mica, the nucleation centres have distances of 50-100 nm even for the first monolayer and substrate temperatures of 200 °C. This shows that the substrate interaction of C59N with mica is larger than that with HOPG and WSe2.

Pietzak, B.; Sommerhalter, C.; Weidinger, A.; Nuber, B.; Reuther, U.; Hirsch, A.

1998-08-01

119

Laminated metal composite formed from low flow stress layers and high flow stress layers using flow constraining elements and making same  

Science.gov (United States)

A laminated metal composite of low flow stress layers and high flow stress layers is described which is formed using flow constraining elements, preferably in the shape of rings, individually placed around each of the low flow stress layers while pressure is applied to the stack to bond the layers of the composite together, to thereby restrain the flow of the low flow stress layers from the stack during the bonding. The laminated metal composite of the invention is made by the steps of forming a stack of alternate layers of low flow stress layers and high flow stress layers with each layer of low flow stress material surrounded by an individual flow constraining element, such as a ring, and then applying pressure to the top and bottom surfaces of the resulting stack to bond the dissimilar layers together, for example, by compression rolling the stack. In a preferred embodiment, the individual flow constraining elements surrounding the layers of low flow stress material are formed of a material which may either be the same material as the material comprising the high flow stress layers, or have similar flow stress characteristics to the material comprising the high flow stress layers. Additional sacrificial layers may be added to the top and bottom of the stack to avoid damage to the stack during the bonding step; and these additional layers may then be removed after the bonding step.

Syn, Chol K. (Moraga, CA); Lesuer, Donald R. (Livermore, CA)

1995-01-01

120

Sacrificial salts: Compensating the initial charge irreversibility in lithium batteries  

Energy Technology Data Exchange (ETDEWEB)

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)

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

121

Surface modification of layered zirconium phosphates: a novel pathway to multifunctional materials.  

Science.gov (United States)

The intercalation of inorganic layered materials has resulted in a wide range of applicability. In such cases the applicability of the material is largely dependent upon the species intercalated within the layer, and the layered material acts largely as a host. Recently, the surface modification of inorganic layered materials has been investigated and it has been shown that the exterior layers can be exclusively functionalized. The advent of surface chemistry allows for the synthesis of particles with both a controlled interlayer and surface. This approach can be used to tailor nanoparticles for specific applications. Herein we review the surface chemistry of ?-zirconium bis(monohydrogen orthophosphate) monohydrate (Zr(HPO4)2·H2O, ?-ZrP) along with some applications of recent interest. Not only can these reactions be applied to ?-ZrP, but similar chemistry can also be expanded to other layered materials and systems. PMID:24737164

Mosby, Brian M; Díaz, Agustín; Clearfield, Abraham

2014-07-21

122

Integration of AlN with molybdenum electrodes and sacrificial amorphous silicon release using XeF2  

Science.gov (United States)

This paper presents a new post-CMOS-compatible integration scheme for AlN-based MEMS devices. The proposed scheme integrates molybdenum (Mo) bottom electrodes with an amorphous silicon (a-Si) sacrificial layer, which is etched using XeF2 to release the MEMS structures. This integration approach faces two potential issues, which are solved in this work: (i) poor adhesion of AlN with a-Si, and (ii) XeF2 attacking the Mo electrode during the removal of the a-Si sacrificial layer. The adhesion problem was solved by introducing a thin oxide layer between a-Si and AlN. The sidewalls of the Mo electrodes were protected by a 0.2 µm thick SiN spacer layer from the XeF2 attack. The robustness of the integration scheme was verified by fabricating an FBAR band pass filter. RF measurements on the FBAR band pass filter show that the proposed integration works well and can be utilized for other AlN-based MEMS devices in post-CMOS applications.

Sharma, Jaibir; Fernando, Sanchitha; Tan, Wee Ming

2014-03-01

123

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

Czech Academy of Sciences Publication Activity Database

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

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

124

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

OpenAIRE

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

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

2013-01-01

125

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

Science.gov (United States)

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.

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

1974-01-01

126

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

Science.gov (United States)

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.

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

127

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

OpenAIRE

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 ...

Masahide Sato, Nobuhiro Tsuji

2004-01-01

128

Surface alloys as interfacial layers between quasicrystalline and periodic materials  

International Nuclear Information System (INIS)

Low adhesion with normal metals is an intrinsic property of many quasicrystalline surfaces. Although this property could be useful to develop low friction or non-stick coatings, it is also responsible for the poor adhesion of quasicrystalline coatings on metal substrates. Here we investigate the possibility of using complex metallic surface alloys as interface layers to enhance the adhesion between quasicrystals and simple metal substrates. We first review some examples where such complex phases are formed as an overlayer. Then we study the formation of such surface alloys in a controlled way by annealing a thin film deposited on a quasicrystalline substrate. We demonstrate that a coherent buffer layer consisting of the ?-Al4Cu9 approximant can be grown between pure Al and the i-Al-Cu-Fe quasicrystal. The interfacial relationships between the different layers are defined by [111]Al parallel [110]Al4Cu9 parallel [5f]i-Al-Cu-Fe

129

Interaction between a compliant material and an unstable boundary layer flow  

International Nuclear Information System (INIS)

The response of a compliant coating to pressure fluctuations due to an unsteady boundary layer flow and the effect of the response on the stability of the flow field are examined. A pseudospectral solution of the Navier--Stokes equations is coupled to a finite element calculation of the behavior of the compliant material. In particular, the effect of material response on the growth rate of a Tollmien--Schlichting type instability in an unstable boundary layer is examined. Results are presented for three materials; a soft polyvinylchloride (PVC), a stiffer PVC, and a two-layer material consisting of a thick layer of soft PVC covered by a thin layer of neoprene. copyright 1988 Academic Press, Inc

130

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

Science.gov (United States)

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.

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

2015-01-01

131

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

CERN Document Server

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 ...

American Society for Testing and Materials. Philadelphia

1997-01-01

132

Shrinking device realized by using layered structures of homogeneous isotropic materials  

International Nuclear Information System (INIS)

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

133

Mott p-n junctions in layered materials  

Science.gov (United States)

The p-n junction has provided the basis for the semiconductor-device industry. Investigations of p-n junctions based on Mott insulators is still in its infancy. Layered Mott insulators, such as cuprates or other transition metal oxides, present a special challenge since strong in-plane correlations are important. Here we model the planes carefully using plaquette cellular dynamical mean field theory with an exact diagonalization solver. The energy associated with interplane hopping is neglected compared with the long-range Coulomb interaction that we treat in the Hartree-Fock approximation. Within this new approach, dynamical layer theory, the charge redistribution is obtained at the final step from minimization of a function of the layer fillings. A simple analytical description of the solution, in the spirit of the Thomas-Fermi theory, reproduces quite accurately the numerical results. Various interesting charge reconstructions can be obtained by varying the Fermi energy differences between both sides of the junction. One can even obtain quasi-two-dimensional charge carriers at the interface, in the middle of a Mott insulating layer. The density of states as a function of position does not follow the simple band bending picture of semiconductors.

Charlebois, M.; Hassan, S. R.; Karan, R.; Sénéchal, D.; Tremblay, A.-M. S.

2013-01-01

134

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

Science.gov (United States)

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

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

2014-12-10

135

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

Directory of Open Access Journals (Sweden)

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.

"Haririan I

2000-08-01

136

Wide-gap layered oxychalcogenide semiconductors: Materials, electronic structures and optoelectronic properties  

International Nuclear Information System (INIS)

Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and their basic optical and electrical properties were examined. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were examined by normal/inverse photoemission spectroscopy and energy band calculations. The results of the examinations suggested that these materials possess unique features more than simple wide-gap semiconductors. Namely, the layered oxychalcogenides are considered to be extremely thin quantum wells composed of the oxide and chalcogenide layers or 2D chalcogenide crystals/molecules embedded in an oxide matrix. Observation of step-like absorption edges, large band gap energy and large exciton binding energy demonstrated these features originating from 2D density of states and quantum size effects in these layered materials

137

Wide-gap layered oxychalcogenide semiconductors: Materials, electronic structures and optoelectronic properties  

Energy Technology Data Exchange (ETDEWEB)

Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and their basic optical and electrical properties were examined. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were examined by normal/inverse photoemission spectroscopy and energy band calculations. The results of the examinations suggested that these materials possess unique features more than simple wide-gap semiconductors. Namely, the layered oxychalcogenides are considered to be extremely thin quantum wells composed of the oxide and chalcogenide layers or 2D chalcogenide crystals/molecules embedded in an oxide matrix. Observation of step-like absorption edges, large band gap energy and large exciton binding energy demonstrated these features originating from 2D density of states and quantum size effects in these layered materials.

Ueda, Kazushige [Department of Materials Science, Faculty of Engineering, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu 804-8550 (Japan)]. E-mail: kueda@che.kyutech.ac.jp; Hiramatsu, Hidenori [Exploratory Research for Advanced Technology-Solution-Orientated Research for Science and Technology (ERATO-SORST), Japan Science and Technology Agency (JST), in the Frontier Collaborative Research Center - FCRC, S2-6F, Mail-box S2-13, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Hirano, Masahiro [Exploratory Research for Advanced Technology-Solution-Orientated Research for Science and Technology (ERATO-SORST), Japan Science and Technology Agency (JST), in the Frontier Collaborative Research Center - FCRC, S2-6F, Mail-box S2-13, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Kamiya, Toshio [Exploratory Research for Advanced Technology-Solution-Orientated Research for Science and Technology (ERATO-SORST), Japan Science and Technology Agency (JST), in the Frontier Collaborative Research Center - FCRC, S2-6F, Mail-box S2-13, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan): Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Hosono, Hideo [Exploratory Research for Advanced Technology-Solution-Orientated Research for Science and Technology (ERATO-SORST), Japan Science and Technology Agency (JST), in the Frontier Collaborative Research Center - FCRC, S2-6F, Mail-box S2-13, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan): Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan): Frontier Collaborative Research Center - FCRC, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan)

2006-02-01

138

Neutron scatering and lattice dynamics of materials with layered structures  

International Nuclear Information System (INIS)

A brief summary of fundamental equations for the Born-von Karman formalism is presented. A force model is then constructed in which certain parameters are used to characterize the interatomic interactions. The inelastic scattering of neutrons has proved to be an invaluable experimental technique for studying in detail, the dynamics of crystalline solids and a brief summary of the main results which are used in the interpretation of experimental data is presented. Atomic vibrations in layered compounds are fully discussed and neutron scattering experiments on layered compounds outlined. Experimental data, with some emphasis on experimental details, are presented for graphite, transition metal dichalcogenides, GaSe, PbI2 and iodine. (C.F.)

139

Zinc-stearate-layered hydroxide nanohybrid material as a precursor to produce carbon nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: > In this work, a new organic-clay nanohybrid material, in which the organic moiety is intercalated between the inorganic layers, was synthesized using stearate anion as a guest and zinc hydroxide nitrate as an inorganic layered host by ion-exchange technique. Carbon nanoparticles were obtained by heat treating of the nanohybrid material, zinc-stearate-layered hydroxide. The proposed method is very simple, the chemicals used in the synthesis are cheap and the manner is economic and suitable for a large scale production of nano-sized carbon nanoparticles. - Abstract: Zinc-stearate-layered hydroxide nanohybrid was prepared using stearate anion as an organic guest, and zinc layered hydroxide nitrate, as a layered inorganic host by the ion-exchange method. Powder X-ray diffraction patterns and Fourier transform infrared results indicated that the stearate anion was actually intercalated into the interlayer of zinc layered hydroxide nitrate and confirmed the formation of the host-guest nanohybrid material. Also, surface properties data showed that the intercalation process has changed the porosity for the as-prepared nanohybrid material in comparison with that of the parent material, zinc hydroxide nitrate. The nanohybrid material was heat-treated at 600 deg. C under argon atmosphere. Stearate anion was chosen as a carbonaceous reservoir in the nanohybrid to produce carbon nanoparticles after heat-treating of the nanohybrid and subsequently acid washing process.

Ghotbi, Mohammad Yeganeh, E-mail: myeganeh@malayeru.ac.ir [Nanomaterials and Nanotechnology Program, Ceramic Engineering Department, Faculty of Engineering, University of Malayer, Malayer (Iran, Islamic Republic of); Materials and Energy Research Center, P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of); Bagheri, Narjes [Materials and Energy Research Center, P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of); Sadrnezhaad, S.K. [Materials and Energy Research Center, P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of); Department of Materials Sciences and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)

2011-02-03

140

Surface alloys as interfacial layers between quasicrystalline and periodic materials  

Energy Technology Data Exchange (ETDEWEB)

Low adhesion with normal metals is an intrinsic property of many quasicrystalline surfaces. Although this property could be useful to develop low friction or non-stick coatings, it is also responsible for the poor adhesion of quasicrystalline coatings on metal substrates. Here we investigate the possibility of using complex metallic surface alloys as interface layers to enhance the adhesion between quasicrystals and simple metal substrates. We first review some examples where such complex phases are formed as an overlayer. Then we study the formation of such surface alloys in a controlled way by annealing a thin film deposited on a quasicrystalline substrate. We demonstrate that a coherent buffer layer consisting of the {gamma}-Al{sub 4}Cu{sub 9} approximant can be grown between pure Al and the i-Al-Cu-Fe quasicrystal. The interfacial relationships between the different layers are defined by [111]{sub Al} parallel [110]{sub Al4Cu9} parallel [5f]{sub i-Al-}C{sub u-Fe}.

Duguet, T; Ledieu, J; Dubois, J M; Fournee, V [Laboratoire de Science et Genie des Materiaux et de Metallurgie, UMR 7584 CNRS-Nancy Universite, Ecole des Mines de Nancy, Parc de Saurupt, F-54042 Nancy (France)], E-mail: fournee@lsg2m.org

2008-08-06

141

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)

142

Tribological and Wear Properties of Multi-Layered Materials  

Directory of Open Access Journals (Sweden)

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.

V. Bria

2011-09-01

143

Atomic layer deposition on polymer based flexible packaging materials: Growth characteristics and diffusion barrier properties  

Energy Technology Data Exchange (ETDEWEB)

One of the most promising areas for the industrial application of atomic layer deposition (ALD) is for gas barrier layers on polymers. In this work, a packaging material system with improved diffusion barrier properties has been developed and studied by applying ALD on flexible polymer based packaging materials. Nanometer scale metal oxide films have been applied to polymer-coated papers and their diffusion barrier properties have been studied by means of water vapor and oxygen transmission rates. The materials for the study were constructed in two stages: the paper was firstly extrusion coated with polymer film, which was then followed by the ALD deposition of oxide layer. The polymers used as extrusion coatings were polypropylene, low and high density polyethylene, polylactide and polyethylene terephthalate. Water vapor transmission rates (WVTRs) were measured according to method SCAN-P 22:68 and oxygen transmission rates (O{sub 2}TRs) according to a standard ASTM D 3985. According to the results a 10 nm oxide layer already decreased the oxygen transmission by a factor of 10 compared to uncoated material. WVTR with 40 nm ALD layer was better than the level currently required for most common dry flexible packaging applications. When the oxide layer thickness was increased to 100 nm and above, the measured WVTRs were limited by the measurement set up. Using an ALD layer allowed the polymer thickness on flexible packaging materials to be reduced. Once the ALD layer was 40 nm thick, WVTRs and O{sub 2}TRs were no longer dependent on polymer layer thickness. Thus, nanometer scale ALD oxide layers have shown their feasibility as high quality diffusion barriers on flexible packaging materials.

Kaeaeriaeinen, Tommi O., E-mail: tommi.kaariainen@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Maydannik, Philipp, E-mail: philipp.maydannik@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Cameron, David C., E-mail: david.cameron@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Lahtinen, Kimmo, E-mail: kimmo.lahtinen@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland); Johansson, Petri, E-mail: petri.johansson@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland); Kuusipalo, Jurkka, E-mail: jurkka.kuusipalo@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland)

2011-03-01

144

Computational synthesis of single-layer GaN on refractory materials  

International Nuclear Information System (INIS)

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

145

Computational synthesis of single-layer GaN on refractory materials  

Energy Technology Data Exchange (ETDEWEB)

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.

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

146

Extremely Efficient Liquid Exfoliation and Dispersion of Layered Materials by Unusual Acoustic Cavitation  

OpenAIRE

Layered materials must be exfoliated and dispersed in solvents for diverse applications. Usually, highly energetic probe sonication may be considered to be an unfavourable method for the less defective exfoliation and dispersion of layered materials. Here we show that judicious use of ultrasonic cavitation can produce exfoliated transition metal dichalcogenide nanosheets extraordinarily dispersed in non-toxic solvent by minimising the sonolysis of solvent molecules. Our method can also lead t...

Joong Tark Han; Jeong In Jang; Haena Kim; Jun Yeon Hwang; Hyung Keun Yoo; Jong Seok Woo; Sua Choi; Ho Young Kim; Hee Jin Jeong; Seung Yol Jeong; Kang-Jun Baeg; Kilwon Cho; Geon-Woong Lee

2014-01-01

147

Layered packaging: A synergistic method of transporting radioactive material  

International Nuclear Information System (INIS)

The DOE certification for a transportation cask used to ship radioactive Krypton 85 from the Idaho Chemical Processing Plant (ICPP) to Oak Ridge National Laboratory (ORNL), was allowed to expire in 1987. The Westinghouse Idaho Nuclear Company (WINCO) was charged by DOE with modifying this cask to meet all current NRC requirements and preparing an updated Safety Analysis Report for Packaging, which would be submitted by DOE to the NRC for certification. However, an urgent need arose for ORNL to receive Krypton 85 which was in storage at the ICPP, which would not allow time to obtain certification of the modified shipping cask. WINCO elected to use a layered shipping configuration in which the gaseous Krypton 85 was placed in the uncertified, modified shipping cask to make use of its shielding and thermal insulation properties. This cask was then inserted into the Model No. 6400 (Super Tiger) packaging using a specially constructed plywood box and polyurethane foam dunnage. Structural evaluations were completed to assure the Super Tiger would provide the necessary impact, puncture, and thermal protection during maximum credible accidents. Analyses were also completed to determine the uncertified Krypton shipping cask would provide the necessary containment and shielding for up to 3.7 E+14 Bq of Krypton 85 when packaged inside the Super Tiger. The resulting reports, based upon this layered packaging concept, were adequate to first obtain DOE certification for several rest obtain DOE certification for several restricted shipments of Krypton 85 and then NRC certification for unrestricted shipments

148

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish 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.

Adolfo, Chaparro Amaya.

2011-12-01

149

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

Directory of Open Access Journals (Sweden)

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.

Adolfo Chaparro Amaya

2011-12-01

150

The effect of sacrificial bonds on the mechanical behavior of a single polymer chain - A Monte Carlo study  

International Nuclear Information System (INIS)

Full text: Understanding the basic building principles of biological materials from a fundamental point of view is a necessary prerequisite for possible transfer of these principles to technology. The byssal thread is an especially fascinating material showing high toughness, stiffness and extensibility. The byssal thread is secreted by marine mussels to adhere to rocky substrates. Being covered with a hard coating providing wear resistance, it shows an extensibility of more than 100 % with the ability of self-healing. Experimental studies on this system suggest that the high extensibility is due to so called 'sacrificial bonds' (SBs). Sacrificial Bonds are weaker than the covalent bonds holding the structure together and they can thermally induced open and close reversibly. The SBs break before the covalent bond rupture, providing hidden length and allowing for efficient energy dissipation. By this effect the toughness of the structure is significantly enhanced. These findings motivate the following simple model. The basic unit is a linear, covalently bonded polymer chain. Some of the monomers (so called sticky sites) can additionally form sacrificial bonds. Starting from a collapsed chain cyclic loading experiments were mimicked by determination of load-displacement curves by calculation of the mean force exerted by the chain for several end-to-end distances. The effect of the density and of the arrangement (ordered, random) of sticky sites on the mechanical behavio of sticky sites on the mechanical behavior of the chain was investigated. For sufficiently high sticky site densities a pronounced hysteresis between stretching and relaxing of the chain could be observed. (author)

151

Self-organized electronic superlattices in layered materials  

Science.gov (United States)

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 background charge density and the frustrating Coulomb interaction strength. The phase diagram displays Arnold tongues obeying a modified Farey tree hierarchy and a devil's staircase, typical of systems with frustration among different scales. We further discuss the competition of these electronic superlattices, recently observed in iron-based superconductors and mixed valence compounds, with in-plane electronically modulated phases.

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

2014-12-01

152

Development of high-performance tri-layer material  

Science.gov (United States)

As chip size and pattern size continue to shrink, the thickness of photo resist is getting thinner and thinner. One of the major reasons is to prevent the small resist features from collapse. It's very challenging to get enough etch resistance from such thin resist thickness. An approach of Si-tri-layer stack which consists of resist, Si ARC (Si contenting anti-reflection coating), organic underlayer from top to bottom has been adopted by many IC makers in the manufacturing of 45 nm node. Even higher resist etching selectivity is needed for 32 nm node. Si ARC, of Si content as high as 43%, provides good etch selectivity. At the same time, tri-layer also provides good control over reflectivity in high NA immersion lithography. However, there are several well know issues concern Si-rich ARC. Resist compatibility and shelf life are on top of the list. An aim of our development work was to overcome those issues in order to produce manufacturing-worthy Si-rich ARC. Several synthesis methods were investigated to form Si-rich ARC film with different properties. Collapse of resist patterns is used as an indicator of lithographic compatibility. Lithographic performance was checked by accelerated shelf life tests at high temperature in order to predict the shelf life at room temperature. It was found that adhesion between resist and Si-rich ARC is improved when contact angle of Si-rich ARC is increased to more than 60 degree. Certain synthesis methods improve shelf life. After optimization of film properties and synthesis methods of Si-rich ARC, SHB-A940 series have best litho compatibility and shelf life is six months at storage temperature below 10°C.

Owe-Yang, D. C.; Yano, Toshiharu; Ueda, Takafumi; Iwabuchi, Motoaki; Ogihara, Tsutomu; Shirai, Shozo

2008-03-01

153

High Curie temperature drive layer materials for ion-implanted magnetic bubble devices  

Science.gov (United States)

Ion implantation of bubble garnets can lower the Curie temperature by 70 C or more, thus limiting high temperature operation of devices with ion-implanted propagation patterns. Therefore, double-layer materials were made with a conventional 2-micron bubble storage layer capped by an ion-implantable drive layer of high Curie temperature, high magnetostriction material. Contiguous disk test patterns were implanted with varying doses of a typical triple implant. Quality of propagation was judged by quasistatic tests on 8-micron period major and minor loops. Variations of magnetization, uniaxial anisotropy, implant dose, and magnetostriction were investigated to ensure optimum flux matching, good charged wall coupling, and wide operating margins. The most successful drive layer compositions were in the systems (SmDyLuCa)3(FeSi)5O12 and (BiGdTmCa)3(FeSi)5O12 and had Curie temperatures 25-44 C higher than the storage layers.

Fratello, V. J.; Wolfe, R.; Blank, S. L.; Nelson, T. J.

1984-01-01

154

Living Bacterial Sacrificial Porogens to Engineer Decellularized Porous Scaffolds  

Science.gov (United States)

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

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

2011-01-01

155

A estrutura sacrificial do compadrio: uma ontologia da desigualdade?  

Directory of Open Access Journals (Sweden)

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".

Marcos Lanna

2009-01-01

156

Optimized cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials  

International Nuclear Information System (INIS)

We present optimized design of cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials. Through an optimization procedure based on genetic algorithm, simpler cloak structure and more realizable material parameters can be achieved with better cloak performance than that of an ideal non-magnetic cloak with a reduced set of parameters. We demonstrate that a cloak shell with only five layers of two normal materials can result in an average 20 dB reduction in the scattering width for all directions when covering the inner conducting cylinder with the cloak. The optimized design can substantially simplify the realization of the invisibility cloak, especially in the optical range.

157

Can nature's design be improved upon? High strength, transparent nacre-like nanocomposites with double network of sacrificial cross links.  

Science.gov (United States)

The preparation of a high-strength and highly transparent nacre-like nanocomposite via layer-by-layer assembly technique from poly(vinyl alcohol) (PVA) and Na+-montmorillonite clay nanosheets is reported in this article. We show that a high density of weak bonding interactions between the polymer and the clay particles: hydrogen, dipole-induced dipole, and van der Waals undergoing break-reform deformations, can lead to high strength nanocomposites: sigmaUTS approximately 150 MPa and E' approximately 13 GPa. Further introduction of ionic bonds into the polymeric matrix creates a double network of sacrificial bonds which dramatically increases the mechanical properties: sigmaUTS approximately 320 MPa and E' approximately 60 GPa. PMID:18590319

Podsiadlo, Paul; Kaushik, Amit K; Shim, Bong Sup; Agarwal, Ashish; Tang, Zhiyong; Waas, Anthony M; Arruda, Ellen M; Kotov, Nicholas A

2008-11-20

158

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)

159

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

Czech Academy of Sciences Publication Activity Database

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

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

160

Improving impact resistance of ceramic materials by energy absorbing surface layers  

Science.gov (United States)

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.

Kirchner, H. P.; Seretsky, J.

1974-01-01

161

Liquid phase exfoliation of 2D layered materials and their application  

Science.gov (United States)

In this work, several materials possessing a layered structure were investigated using a technique of exfoliation in liquid phase to produce few- to mono-layers of the material. Materials exfoliated in such a way included graphite, boron nitride, molybdenum disulfide and tungsten disulfide. Subsequent transmission electron microscopy and accompanying electron diffraction patterns revealed that few and mono layer forms of these materials have been realized through this exfoliation method. Ultraviolet-visible spectroscopy confirmed the shifting of the band gaps in molybdenum and tungsten disulfides that is predicted in reducing the number of layers of these materials and was also used to confirm the band gap of the boron nitride. As a potential application, exfoliated molybdenum disulfide was used in the construction of electrodes for electrical charge storage in an electrochemical double layer capacitor, or supercapacitor, style device. Cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy measurements were performed using three different electrolytes, which showed good capacitive behavior for these devices. Using the data from electrochemical impedance spectroscopy, equivalent circuit models were generated to represent the systems in different electrolytes. From this, it was determined that the capacitive behavior of these systems was partially diffusion limited.

Winchester, Andrew J.

162

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.

163

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

164

Ab initio modeling of layered materials with the CRYSTAL code: an overview  

OpenAIRE

Ab initio simulations play an increasingly relevant role in the study of layered materials. Here we give an overview of the capabilities of modeling tools as applied to the characterization of simple layered hydroxides (e.g. alkali metal and aluminum hydroxides) and clays (e.g. kaolinite and lizardite). In particular, applications of the CRYSTAL code, in the study of such systems, are discussed.

Dovesi, Roberto; Ugliengo, Piero; Civalleri, Bartolomeo

2009-01-01

165

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

Energy Technology Data Exchange (ETDEWEB)

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|Me{sup z+} 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.

Jagminas, Arunas, E-mail: jagmin@ktl.mii.l [Institute of Chemistry, A. Gostauto 9, 01108 Vilnius (Lithuania); Cesuniene, Asta [Institute of Chemistry, A. Gostauto 9, 01108 Vilnius (Lithuania); Vrublevsky, Igor [Department of Microelectronics, Belarusian State University of Informatics and Radioelectronics, 6 Brovka str, Minsk 220013 (Belarus); Jasulaitiene, Vitalija; Ragalevicius, Rimas [Institute of Chemistry, A. Gostauto 9, 01108 Vilnius (Lithuania)

2010-03-30

166

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.

167

Integration of III–V materials and Si-CMOS through double layer transfer process  

Science.gov (United States)

A method to integrate III–V compound semiconductor and SOI-CMOS on a common Si substrate is demonstrated. The SOI-CMOS layer is temporarily bonded on a Si handle wafer. Another III–V/Si substrate is then bonded to the SOI-CMOS containing handle wafer. Finally, the handle wafer is released to realize the SOI-CMOS on III–V/Si hybrid structure on a common substrate. Through this method, high temperature III–V materials growth can be completed without the presence of the temperature sensitive CMOS layer, hence damage to the CMOS layer is avoided.

Lee, Kwang Hong; Bao, Shuyu; Fitzgerald, Eugene; Tan, Chuan Seng

2015-03-01

168

Wide-angle X-ray diffraction of materials comprising layer-type molecules  

International Nuclear Information System (INIS)

The shapes of the wide-angle X-ray reflexion profiles produced by materials comprising layer-type molecules, such as carbon fibres and pyrolytic graphites, are affected by distortions, sizes and preferential orientation of the crystallites. In the present study, the diffraction intensity distribution of layer-type materials has been deduced theoretically as a function of structural parameters and measuring direction. The reflexion profiles of carbon fibres have been simulated to investigate the effects of structural parameters on the modulation of the diffraction pattern. (orig.)

169

Suitability of Structural Aluminium Profiles as Sacrificial Anode for Carbon Steel  

OpenAIRE

The life of low carbon steels in many small scale structures can be remarkably prolonged by complementary sacrificial anode cathodic protection (SACP) but for constraints in availability of specialty anodes. Suitability of commonly available structural aluminium profiles as sacrificial anodes for low carbon steel has been investigated. Three different profiles were studied. Bare and coated steel samples were found to migrate clearly too cathodic potential regimes when coupled with the press-f...

Otunniyi, Iyiola O.; Oloruntoba, Daniel T.

2012-01-01

170

Tri-metallic transition metal–nitrogen–carbon catalysts derived by sacrificial support method synthesis  

International Nuclear Information System (INIS)

A series of tri-metallic oxygen reduction catalysts derived from pyrolyzed Fe-M1-M2 (where M = Co, Ni, Cu and Mn) and 4-aminoantipyrine (Fe-M1-M2-AAPyr) were prepared using a sacrificial support method (SSM). The influence of the iron interacting with the two transition metals on the catalytic activity of the oxygen reduction reaction (ORR) was investigated. This series of materials was analyzed and characterized by scanning electron microscopy (SEM) and the BET method (BET) in order to establish structural morphology, and rotating ring disk electrode (RRDE) experiments were performed to evaluate catalytic activity. The results were then correlated to one another, thereby establishing a composition to function relationship. Data from the ring current was used to execute a mechanistic study of the materials for the ORR, and it was found that supplementation of the iron with transition metals significantly improved catalytic activity, in addition to decreasing the hydrogen peroxide yield. The most pronounced enhancement of ORR catalysts is when the base transition metal Fe is supplemented with Co as a secondary metal and Cu or Mn are the tertiary metal in the system

171

An experimental investigation of dynamic crack propagation in a brittle material reinforced with a ductile layer  

Science.gov (United States)

The fracture behavior of a dynamically loaded edge crack in a brittle-ductile layered material, as a function of applied loading rate, was experimentally investigated. Layered specimens were prepared by sandwiching a thin layer of ductile aluminum between two thick layers of brittle Homalite-100. The layers were bonded using Loctite Depend 330 adhesive, and a naturally sharp edge crack was introduced in one of the Homalite-100 layers. These single-edge notched specimens were loaded in dynamic three-point bending using a modified Hopkinson bar. The fracture process was imaged in real time using dynamic photoelasticity in conjunction with digital high-speed photography, and the applied load and load-point displacement histories were determined from the strain signals recorded at two locations on the Hopkinson bar. The results of this study indicated two distinct mechanisms of dynamic failure, depending on the applied loading rate. At lower loading rates, the starter crack arrested on reaching the aluminum layer and then caused delamination along the aluminum-Homalite interface. On the contrary, as the loading rate was increased, interfacial delamination was followed by crack re-initiation in the Homalite layer opposite to the initial starter crack. It was determined that the times required for crack initiation, delamination and crack re-initiation decreased as the loading rate was increased. However, it was also observed that the applied load values associated with each event increased with increasing loading rate. These observations indicate that both the dynamic failure process and plausibly the failure mode transition are affected by the rate-dependent properties of Homalite, aluminum and the interfacial bond. Finally, based on the measured peak loads and the observed failure mechanisms it was concluded that the incorporation of a thin ductile reinforcement layer can increase both the overall fracture toughness and strength of a nominally brittle material.

Singh, Raman P.; Parameswaran, Venkitanarayanan

2003-10-01

172

Simulation of trapping properties of high ? material as the charge storage layer for flash memory application  

International Nuclear Information System (INIS)

We investigated the trapping properties of high ? material as the charge storage layer in non-volatile flash memory devices using a two-dimensional device simulator, Medici. The high ? material is sandwiched between two silicon oxide layers, resulting in the Silicon-Oxide-High ?-Oxide-Silicon (SOHOS) structure. The trap energy levels of the bulk electron traps in high ? material were determined. The programming and erasing voltage and time using Fowler Nordheim tunneling were estimated by simulation. The effect of deep level traps on erasing was investigated. Also, the effect of bulk traps density, thickness of block oxide and thickness of high ? material on the threshold voltage of the device was simulated

173

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

Energy Technology Data Exchange (ETDEWEB)

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.

Krumhansl, James L; Nenoff, Tina M

2015-01-06

174

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

Science.gov (United States)

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.

Krumhansl, James L; Nenoff, Tina M

2013-02-26

175

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

176

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

DEFF Research Database (Denmark)

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.

Nielsen, Kim Lau

2012-01-01

177

Nondestructive metrology by optical coherence tomography empowering manufacturing iterations of layered polymeric optical materials  

Science.gov (United States)

In recent years, there has been an ever-growing interest in exploring different optical materials and components to develop compact and effective optical systems. The design and fabrication of high-performance optics require nondestructive metrology techniques to inspect the samples. We have investigated the capability of optical coherence tomography (OCT) to nondestructively characterize layered polymeric materials. Using a custom developed Gabor-domain optical coherence microscopy system centered at 800 nm with 120 nm full width at half maximum enabling unprecedented 2 ?m resolution both laterally and axially in an 8 mm3 volume, we investigated the internal structure of 50 ?m thick films and layered sheets, which prompted the manufacturing process to adopt a compatibilization technique. Based on a custom swept-source OCT system centered at 1320 nm with expanded imaging field-of-view and latest depth of imaging extended to ˜5 mm, we performed nondestructive metrology of the layer thickness profiles over the depth of a monolithic layered sheet and diagnosed a film compression issue within the sheet. With the OCT metrology, the manufacturing process has been advanced and the layer thickness profile of a recent layered gradient refractive index sheet shows improved uniformity through depth.

Yao, Jianing; Meemon, Panomsak; Lee, Kye-Sung; Rolland, Jannick P.

2013-11-01

178

Struvite precipitation and phosphorus removal using magnesium sacrificial anode.  

Science.gov (United States)

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

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

2014-04-01

179

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

180

Evidence for Multiple Layers of Phyllosilicate-Bearing Materials in Northwest Noachis Terra, Mars  

Science.gov (United States)

A widespread phyllosilicate-bearing unit has been identified in NW Noachis Terra: Al-smectites comprise the upper member and Fe/Mg-smectites the lower. We present evidence of a second layer of Fe/Mg-smectite bearing materials above the Al-smectites.

Buczkowski, D. L.; Ackiss, S. E.; Seelos, K. D.; Murchie, S.; Seelos, F.; Malaret, E.; Hash, C.

2014-07-01

181

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)

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.

Ansbæk, Thor; Semenova, Elizaveta

2013-01-01

182

Film of lignocellulosic carbon material for self-supporting electrodes in electric double-layer capacitors  

Directory of Open Access Journals (Sweden)

Full Text Available A novel thin, wood-based carbon material with heterogeneous pores, film of lignocellulosic carbon material (FLCM, was successfully fabricated by carbonizing softwood samples of Picea jezoensis (Jezo spruce. Simultaneous increase in the specific surface area of FLCM and its affinity for electrolyte solvents in an electric double-layer capacitor (EDLC were achieved by the vacuum ultraviolet/ozone (VUV/O3 treatment. This treatment increased the specific surface area of FLCM by 50% over that of original FLCM. The results obtained in this study confirmed that FLCM is an appropriate self-supporting EDLC electrode material without any warps and cracks.

Tsubasa Funabashi

2013-09-01

183

Film of lignocellulosic carbon material for self-supporting electrodes in electric double-layer capacitors  

Science.gov (United States)

A novel thin, wood-based carbon material with heterogeneous pores, film of lignocellulosic carbon material (FLCM), was successfully fabricated by carbonizing softwood samples of Picea jezoensis (Jezo spruce). Simultaneous increase in the specific surface area of FLCM and its affinity for electrolyte solvents in an electric double-layer capacitor (EDLC) were achieved by the vacuum ultraviolet/ozone (VUV/O3) treatment. This treatment increased the specific surface area of FLCM by 50% over that of original FLCM. The results obtained in this study confirmed that FLCM is an appropriate self-supporting EDLC electrode material without any warps and cracks.

Funabashi, Tsubasa; Mizuno, Jun; Sato, Masamichi; Kitajima, Masao; Matsuura, Makoto; Shoji, Shuichi

2013-09-01

184

High-temperature heat and mass transfer in a layer of moisture-containing fireproof material  

International Nuclear Information System (INIS)

On the basis of analysis and of generalization of results of the experimental investigations into the basic mechanisms of high-temperature heat and mass transfer in a layer of porous moisture-containing fireproofing material one made a mathematical model of the given process. Account for all basic physical and chemical processes occurring in moisture-containing fireproofing materials under up to high temperature heating represents a distinguishing feature of the model. The results of numerical studies of the model agree well with the experimental data on some moisture-containing fire-proofing materials

185

Modifying the Interlayer Interaction in Layered Materials with an Intense IR Laser.  

Science.gov (United States)

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

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

2015-03-20

186

Direct formation of gold nanoparticles on substrates using a novel ZnO sacrificial templated-growth hydrothermal approach and their properties in organic memory device  

OpenAIRE

This study describes a novel fabrication technique to grow gold nanoparticles (AuNPs) directly on seeded ZnO sacrificial template/polymethylsilsesquioxanes (PMSSQ)/Si using low-temperature hydrothermal reaction at 80°C for 4 h. The effect of non-annealing and various annealing temperatures, 200°C, 300°C, and 400°C, of the ZnO-seeded template on AuNP size and distribution was systematically studied. Another PMMSQ layer was spin-coated on AuNPs to study the memory properties of organic insu...

Goh, Lean Poh; Razak, Khairunisak Abdul; Ridhuan, Nur Syafinaz; Cheong, Kuan Yew; Ooi, Poh Choon; Aw, Kean Chin

2012-01-01

187

The texture changes of surface layer during material transfer in tribological pair: carbon material - steel  

International Nuclear Information System (INIS)

Often in the areas of dry friction and solid lubrication a material transfer occurs. On both surfaces: bearing bush and journal there is formed a transfer film strongly adhering to the substrate. Owing to friction phenomena the structure of subsurface zone is changed. The reflected beam Schulz method measurements revealed that the changes refer to texture of subsurface zone too. (author)

188

A thin layer including a carbon material improves the rate capability of an electric double layer capacitor  

Science.gov (United States)

We present a new method to improve the rate capability of an electric double layer capacitor (EDLC) using a thin polymer layer having a high concentration of carbon material on a current collector (CLC). A novel thermocuring coating composed of a glycol-chitosan, a pyromellitic acid and a conductive carbon powder can form stable CLC on a metal foil current collector simply by spreading and curing at 160 °C for a couple of minutes. We compared the performance of some demonstration EDLC cells using three kinds of current collector: a conventional aluminum oxide foil for EDLC, an aluminum foil and an aluminum foil with CLC. The cell with the CLC had a much higher rate capability than the cell without CLC. Only the CLC cell was able to discharge at a current density of 500C. This cell shows a slight deterioration in capacity in a high temperature, continuous charging, life test, and the CLC has a suppressing effect on the internal resistance increase of EDLCs. The use of a CLC film current collector is one of the most effective and simple methods for the improvement of EDLC rate performance. In particular, a current collector consisting of aluminum foil coupled with a CLC promises to be a low cost alternative to the aluminum oxide foil commonly used in EDLCs.

Sato, Takaya; Marukane, Shoko; Morinaga, Takashi; Uemura, Taichi; Fukumoto, Kunihiro; Yamazaki, Satoshi

2011-03-01

189

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.

190

Highly efficient gate-tunable photocurrent generation in vertical heterostructures of layered materials  

Science.gov (United States)

Layered materials of graphene and MoS2, for example, have recently emerged as an exciting material system for future electronics and optoelectronics. Vertical integration of layered materials can enable the design of novel electronic and photonic devices. Here, we report highly efficient photocurrent generation from vertical heterostructures of layered materials. We show that vertically stacked graphene-MoS2-graphene and graphene-MoS2-metal junctions can be created with a broad junction area for efficient photon harvesting. The weak electrostatic screening effect of graphene allows the integration of single or dual gates under and/or above the vertical heterostructure to tune the band slope and photocurrent generation. We demonstrate that the amplitude and polarity of the photocurrent in the gated vertical heterostructures can be readily modulated by the electric field of an external gate to achieve a maximum external quantum efficiency of 55% and internal quantum efficiency up to 85%. Our study establishes a method to control photocarrier generation, separation and transport processes using an external electric field.

Yu, Woo Jong; Liu, Yuan; Zhou, Hailong; Yin, Anxiang; Li, Zheng; Huang, Yu; Duan, Xiangfeng

2013-12-01

191

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

Directory of Open Access Journals (Sweden)

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.

Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

2004-01-01

192

Frequency characterization of thin soft magnetic material layers used in spiral inductors  

Energy Technology Data Exchange (ETDEWEB)

The paper details the characterization of thin magnetic materials layers, particularly soft materials, with respect to their behaviour in frequency (from 10 MHz to 1 GHz). The proposed method is suitable for any soft but insulating magnetic material; Yttrium Iron Garnet (YIG) is used as an example. The principle is based on a comparison between simulations for different values of the permeability and measurement values versus frequency of planar inductor structures; an experimental validation is proposed as well. Thin magnetic material is first deposited on an alumina substrate using RF sputtering technique; a planar spiral winding of copper is then deposited on the magnetic material by the same technique. The effective permeability versus frequency is obtained by comparing two samples of spiral windings with and without magnetic material. Network analyser measurements on samples of various geometrical dimensions and of different thicknesses are necessary to determine the effective magnetic permeability; we have obtained a relative effective permeability of about 30 for seven turns spiral inductor of a 17 {mu}m YIG film. - Highlights: Black-Right-Pointing-Pointer A simple and original method is presented for the characterization of soft magnetic layer. Black-Right-Pointing-Pointer This is a non-destructive method based on standard equipment. Black-Right-Pointing-Pointer The principle is based on a comparison between simulations and measurement. Black-Right-Pointing-Pointer An experimental validation is proposed as well.

Kriga, Adoum; Allassem, Desire [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France); Soultan, Malloum [Universite de N' Djamena N' Djamena (Chad); Chatelon, Jean-Pierre; Siblini, Ali [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France); Allard, Bruno [Laboratoire Ampere INSA-Lyon 20, avenue Einstein 69621 Villeurbanne Cedex France (France); Rousseau, Jean Jacques, E-mail: rousseau@univ-st-etienne.fr [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France)

2012-07-15

193

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

Science.gov (United States)

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.

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

2013-07-01

194

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

Science.gov (United States)

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.

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

2015-03-01

195

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

Directory of Open Access Journals (Sweden)

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.

ISMAEL HARTRIAN

2000-07-01

196

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

Science.gov (United States)

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.

Briola, Maria

2015-02-01

197

Surface wave sensors based on nanometric layers of strongly absorbing materials.  

Science.gov (United States)

We demonstrate the excitation of guided modes in thin layers of strongly absorbing chalcogenide glasses. These modes are similar to surface plasmon polaritons in terms of resonance width and shift with changes in the permittivity of the surrounding medium. We exploit these characteristics to demonstrate a high sensitivity chalcogenide glass refractive index sensor that outperforms gold surface plasmon resonance sensors at short wavelengths in the visible. This demonstration opens a new range of possibilities for sensing using different materials. PMID:22535033

Zhang, Yichen; Arnold, Christophe; Offermans, Peter; Gómez Rivas, Jaime

2012-04-23

198

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

OpenAIRE

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 (...

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

2014-01-01

199

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

DEFF Research Database (Denmark)

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.

Kaiser, M.; Hupfer, T.

2013-01-01

200

Role of surface chemistry on electric double layer capacitance of carbon materials  

OpenAIRE

A large number of porous carbon materials with di?erent properties in terms of porosity, surface chemistry and electrical conductivity, were prepared and systematically studied as electric double layer capacitors in aqueous medium with H2SO4 as electrolyte. The precursors used are an anthracite, general purpose carbon ?bres and high performance carbon ?bres, which were activated by KOH, NaOH, CO2 and steam at di?erent conditions. Among all of them, an activated anthracite with a BE...

Bleda Marti?nez, Mari?a Jesu?s; Macia? Agullo?, Juan Antonio; Lozano Castello?, Dolores; Morallo?n Nu?n?ez, Emilia; Cazorla Amoro?s, Diego; Linares Solano, A?ngel

2005-01-01

201

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

Directory of Open Access Journals (Sweden)

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.

M. Drobne

2014-10-01

202

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

Directory of Open Access Journals (Sweden)

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.

Lufa Shen

2010-05-01

203

Tin disulfide-an emerging layered metal dichalcogenide semiconductor: materials properties and device characteristics.  

Science.gov (United States)

Layered metal dichalcogenides have attracted significant interest as a family of single- and few-layer materials that show new physics and are of interest for device applications. Here, we report a comprehensive characterization of the properties of tin disulfide (SnS2), an emerging semiconducting metal dichalcogenide, down to the monolayer limit. Using flakes exfoliated from layered bulk crystals, we establish the characteristics of single- and few-layer SnS2 in optical and atomic force microscopy, Raman spectroscopy and transmission electron microscopy. Band structure measurements in conjunction with ab initio calculations and photoluminescence spectroscopy show that SnS2 is an indirect bandgap semiconductor over the entire thickness range from bulk to single-layer. Field effect transport in SnS2 supported by SiO2/Si suggests predominant scattering by centers at the support interface. Ultrathin transistors show on-off current ratios >10(6), as well as carrier mobilities up to 230 cm(2)/(V s), minimal hysteresis, and near-ideal subthreshold swing for devices screened by a high-k (deionized water) top gate. SnS2 transistors are efficient photodetectors but, similar to other metal dichalcogenides, show a relatively slow response to pulsed irradiation, likely due to adsorbate-induced long-lived extrinsic trap states. PMID:25247490

Huang, Yuan; Sutter, Eli; Sadowski, Jerzy T; Cotlet, Mircea; Monti, Oliver L A; Racke, David A; Neupane, Mahesh R; Wickramaratne, Darshana; Lake, Roger K; Parkinson, Bruce A; Sutter, Peter

2014-10-28

204

Mixed-material layer formation on graphite exposed to deuterium plasmas containing beryllium  

Science.gov (United States)

Mixed-materials formation and properties are examined for graphite-target surfaces exposed to deuterium plasma containing small amounts of ionized beryllium. Targets are exposed to plasma in the PISCES-B divertor plasma simulator under conditions relevant to the operation of the graphite-strike plates in ITER. X-ray photoelectron spectroscopy (XPS) is used to analyze targets following exposure and reveals chemical reaction of the surface graphite with the incident-plasma beryllium flux. Partial surface carbidization is observed for a target exposure temperature of 450 K and full surface carbidization with Be 2C at temperatures higher than this up to 1000 K. Rutherford backscattering spectrometry (RBS) data reveal a mixed-material layer of Be/C of varying-elemental concentration up to ˜1 ?m thick. Hydrogen-isotope retention in targets is measured using thermal-desorption spectrometry (TDS) and D- 3He nuclear-reaction analysis (NRA). Targets exposed to deuterium plasma exhibit retention consistent with values in the literature but extrapolated to the higher ion fluences possible in PISCES simulators. In contrast, targets with a mixed-material Be/C layer are found to have increased retention by a factor of ˜4 at low temperature ˜300 K and ˜2 at higher temperature ˜1000 K. Simulation of NRA spectra reveals that most of the increased inventory is accumulated in the mixed layer.

Baldwin, M. J.; Doerner, R. P.; Nishijima, D.; Schmid, K.; Whyte, D. G.; Kulpin, J. G.; Wright, G.

2006-11-01

205

Organic depth profiling of a nanostructured delta layer reference material using large argon cluster ions.  

Science.gov (United States)

Cluster ion beams have revolutionized the analysis of organic surfaces in time-of-flight secondary ion mass spectrometry and opened up new capabilities for organic depth profiling. Much effort has been devoted to understanding the capabilities and improving the performance of SF(5)(+) and C(60)(n+), which are successful for many, but not all, organic materials. Here, we explore the potential of organic depth profiling using novel argon cluster ions, Ar(500)(+) to Ar(1000)(+). We present results for an organic delta layer reference sample, consisting of ultrathin "delta" layers of Irganox 3114 (approximately 2.4 nm) embedded between thick layers of Irganox 1010 (approximately 46 or 91 nm). This indicates that, for the reference material, major benefits can be obtained with Ar cluster ions, including a constant high sputtering yield throughout a depth of approximately 390 nm, and an extremely low sputter-induced roughness of resolution is currently limited by an instrumental artifact, and may not be the best attainable, these initial results strongly indicate the potential to achieve high depth resolution and suggest that Ar cluster ions may have a major role to play in the depth profiling of organic materials. PMID:19957960

Lee, J L S; Ninomiya, S; Matsuo, J; Gilmore, I S; Seah, M P; Shard, A G

2010-01-01

206

Suitability of Structural Aluminium Profiles as Sacrificial Anode for Carbon Steel  

Directory of Open Access Journals (Sweden)

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

Iyiola O. OTUNNIYI

2012-11-01

207

New Material Development for Surface Layer and Surface Technology in Tribology Science to Improve Energy Efficiency  

Science.gov (United States)

This paper reviews the development of new material and surface technology in tribology and its contribution to energy efficiency. Two examples of the economic benefits, resulted from the optimum tribology in the transportation sector and the manufacturing industry are discussed. The new materials are proposed to modify the surface property by laminating the bulk material with thin layer/coating. Under a suitable condition, the thin layer on a surface can provide a combination of good wear, a low friction and corrosion resistance for the mechanical components. The innovation in layer technology results molybdenum disulfide (MoS2), diamond like carbon (DLC), cubic boron nitride (CBN) and diamond which perform satisfactory outcome. The application of the metallic coatings to carbon fibre reinforced polymer matrix composites (CFRP) has the capacity to provide considerable weight and power savings for many engineering components. The green material for lubricant and additives such as the use of sunflower oil which possesses good oxidation resistance and the use of mallee leaves as bio-degradable solvent are used to answer the demand of the environmentally friendly material with good performance. The tribology research implementation for energy efficiency also touches the simple things around us such as: erasing the laser-print in a paper with different abrasion techniques. For the technology in the engineering surface, the consideration for generating the suitable surface of the components in running-in period has been discussed in order to prolong the components life and reduce the machine downtime. The conclusion, tribology can result in reducing manufacturing time, reducing the maintenance requirements, prolonging the service interval, improving durability, reliability and mechanical components life, and reducing harmful exhaust emission and waste. All of these advantages will increase the energy efficiency and the economic benefits.

Ismail, R.; Tauviqirrahman, M.; Jamari, Jamari; Schipper, D. J.

2009-09-01

208

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

OpenAIRE

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

Petrica, Adrian V.; Mircea Megheles

2005-01-01

209

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

Directory of Open Access Journals (Sweden)

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

Adrian V. Petrica

2005-10-01

210

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)

211

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

212

Nanoarchitectured materials composed of fullerene-like spheroids and disordered graphene layers with tunable mechanical properties  

Science.gov (United States)

Type-II glass-like carbon is a widely used material with a unique combination of properties including low density, high strength, extreme impermeability to gas and liquid and resistance to chemical corrosion. It can be considered as a carbon-based nanoarchitectured material, consisting of a disordered multilayer graphene matrix encasing numerous randomly distributed nanosized fullerene-like spheroids. Here we show that under both hydrostatic compression and triaxial deformation, this high-strength material is highly compressible and exhibits a superelastic ability to recover from large strains. Under hydrostatic compression, bulk, shear and Young’s moduli decrease anomalously with pressure, reaching minima around 1–2?GPa, where Poisson’s ratio approaches zero, and then revert to normal behaviour with positive pressure dependences. Controlling the concentration, size and shape of fullerene-like spheroids with tailored topological connectivity to graphene layers is expected to yield exceptional and tunable mechanical properties, similar to mechanical metamaterials, with potentially wide applications.

Zhao, Zhisheng; Wang, Erik F.; Yan, Hongping; Kono, Yoshio; Wen, Bin; Bai, Ligang; Shi, Feng; Zhang, Junfeng; Kenney-Benson, Curtis; Park, Changyong; Wang, Yanbin; Shen, Guoyin

2015-02-01

213

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

Science.gov (United States)

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.

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

2014-06-01

214

In situ ellipsometry of surface layer of non-metallic transparent materials during its finish processing  

International Nuclear Information System (INIS)

For modern technology applications it is important to develop non-contact methods of control of the modification of dielectric materials surface layer. The aim of the work is to determine the level of roughness changes in the surface layer of non-metallic material, optical glass BK-7, and to control it by in situ ellipsometry. The probing light spot was formed at a second (lower) reflective surface of the plate being studied during its mechanical processing at direct observation of these changes. The fine mechanical polishing was carried out for 2 hours by using the grinding-polishing machine installed directly on the sample table of ellipsometer LEF-3M. The angle of light incidence was close to 70 degree. The ellipsometric parameters, were determined within the mechanically processed area. For this purpose, the probing light beam passed two times through the sample and then returned to the initial (air) medium, where its polarization state was studied. The polarized beam falls on lower plate surface polished by conventional technology using grinding-polishing CeO2-based instrument 'Aquapol' (grain size 1 micron). The time dependences of the ellipsometric parameters during the surface layer treatment were studied. In these dependences the tendency of changes of ellipsometric parameters indicates the surface roughness enhancement

215

Formation of growing integrated layer [GIL] between ceramics and metallic materials for improved adhesion performance  

International Nuclear Information System (INIS)

In the ceramic/metal joining and coating, the most difficult problem is how to overcome poor adhesion of ceramic layers by their cracking and/or peeling arising from their intrinsic brittleness. On the basis of accumulated results and discussion, we propose a novel concept and technology of formation 'Graded Intermediate Layer' or 'Growing Integrated Layer' [GIL] between ceramics and metallic materials to improve the adhesion performance. Those GIL(s) can be prepared from a component of the metallic materials by chemical and/or electrochemical reactions in a solution at low temperatures of RT-200 deg. C. BaTiO3 or SrTiO3/TiOx GIL films on Ti plates formed by hydrothermal-electrochemical method showed good adhesion. CaTiO3/Al2O3/Ti2Al GIL films on TiAl exhibited excellent adhesion and anti-oxidation performances. The GIL strategy is effective for metallic alloys and bulk metallic glasses because they generally contain active component(s)

216

Formation of growing integrated layer [GIL] between ceramics and metallic materials for improved adhesion performance  

Energy Technology Data Exchange (ETDEWEB)

In the ceramic/metal joining and coating, the most difficult problem is how to overcome poor adhesion of ceramic layers by their cracking and/or peeling arising from their intrinsic brittleness. On the basis of accumulated results and discussion, we propose a novel concept and technology of formation 'Graded Intermediate Layer' or 'Growing Integrated Layer' [GIL] between ceramics and metallic materials to improve the adhesion performance. Those GIL(s) can be prepared from a component of the metallic materials by chemical and/or electrochemical reactions in a solution at low temperatures of RT-200 deg. C. BaTiO{sub 3} or SrTiO{sub 3}/TiO{sub x} GIL films on Ti plates formed by hydrothermal-electrochemical method showed good adhesion. CaTiO{sub 3}/Al{sub 2}O{sub 3}/Ti{sub 2}Al GIL films on TiAl exhibited excellent adhesion and anti-oxidation performances. The GIL strategy is effective for metallic alloys and bulk metallic glasses because they generally contain active component(s)

Yoshimura, Masahiro [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama (Japan)], E-mail: yoshimura@msl.titech.a.jp; Onoki, Takamasa [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama (Japan); Fukuhara, Mikio; Wang Xinmin [Institute of Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai (Japan); Nakata, Kazuhiro; Kuroda, Toshio [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka (Japan)

2008-02-25

217

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)

218

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

Science.gov (United States)

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.

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

1997-01-01

219

Thermal properties measurement of dry bulk materials with a cylindrical three layers device.  

Science.gov (United States)

This paper presents a new method dedicated to thermal properties (conductivity and diffusivity) measurement of dry bulk materials including powders. The cylindrical three layers experimental device (brass/bulk material/stainless steel) and the principle of the measurement method based on a crenel thermal excitation are presented. The one-dimensional modeling of the system is used for a sensitivity analysis and to calculate the standard deviation of the estimation error. Experimental measurements are carried out on three bulk materials: glass beads, cork granules, and expanded polystyrene beads. The estimated thermal properties are compared with the values obtained by other measurement methods. Results are in good agreement with theoretical predictions: both thermal conductivity and diffusivity can be estimated with a good accuracy for low density material like cork granules or expanded polystyrene beads since only thermal diffusivity can be estimated for heavier materials like glass beads. It is finally shown that this method like all transient methods is not suited to the thermal characterization of wet bulk materials. PMID:24089849

Jannot, Y; Degiovanni, A

2013-09-01

220

Thermal properties measurement of dry bulk materials with a cylindrical three layers device  

Science.gov (United States)

This paper presents a new method dedicated to thermal properties (conductivity and diffusivity) measurement of dry bulk materials including powders. The cylindrical three layers experimental device (brass/bulk material/stainless steel) and the principle of the measurement method based on a crenel thermal excitation are presented. The one-dimensional modeling of the system is used for a sensitivity analysis and to calculate the standard deviation of the estimation error. Experimental measurements are carried out on three bulk materials: glass beads, cork granules, and expanded polystyrene beads. The estimated thermal properties are compared with the values obtained by other measurement methods. Results are in good agreement with theoretical predictions: both thermal conductivity and diffusivity can be estimated with a good accuracy for low density material like cork granules or expanded polystyrene beads since only thermal diffusivity can be estimated for heavier materials like glass beads. It is finally shown that this method like all transient methods is not suited to the thermal characterization of wet bulk materials.

Jannot, Y.; Degiovanni, A.

2013-09-01

221

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

KAUST Repository

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.

Saeed, Yasir

2014-05-11

222

Effects of shroud gas injection on material properties of tungsten layers coated by plasma spraying  

International Nuclear Information System (INIS)

Coated tungsten layers on stainless steel substrates were are produced by atmosphere plasma spraying. A shroud gas injection method was employed to reduce the ambient air entrainment into the plasma jets. The effects of shroud gas on the material properties of the tungsten layers were investigated by finding the dependence of oxide content, coating thickness and porosity on the injection velocity, shielding width, and mass flux of the shroud gas. The high injection velocity was more effective than thick shroud shielding in protecting the plasma jets from ambient air engulfment, and the mass flux of the shroud gas showed negligibly small effects on the suppression of air entrainment. Therefore, in order to produce a thick tungsten coating with low porosity and oxide contents, high injection velocity with a limited flow rate is a desirable operating condition for shroud gas injection in atmospheric plasma spraying.

223

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

International Nuclear Information System (INIS)

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 90Sr/90Y 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 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 cm2 which is usually applied to operational radiation protection. (authors)

224

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

Science.gov (United States)

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

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

2015-03-01

225

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

Science.gov (United States)

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.

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

2015-04-01

226

Processing of hazardous material, or damage treatment method for shallow layer underground storage structure  

International Nuclear Information System (INIS)

In radioactive waste processing facilities and shallow layer underground structures for processing hazardous materials, sheet piles having freezing pipes at the joint portions are spiked into soils at the periphery of a damaged portion of the shallow layer underground structure for processing or storing hazardous materials. Liquid nitrogen is injected to the freezing pipes to freeze the joint portions of adjacent sheet piles. With such procedures, continuous waterproof walls are formed surrounding the soils at the peripheries of the damaged portion. Further, freezing pipes are disposed in the surrounding soils, and liquid nitrogen is injected to freeze the soils. The frozen soils are removed, and artificial foundation materials are filled in the space except for the peripheries of the damaged portion after the removal thereof, and liquid suspension is filled in the peripheries of the damaged portion, and restoration steps for closing the damaged portion are applied. Then, the peripheries of the damaged portion are buried again. With such procedures, series of treatments for removing contaminated soils and repairing a damaged portion can be conducted efficiently at a low cost. (T.M.)

227

Properties of photocured epoxy resin materials for application in piezoelectric ultrasonic transducer matching layers.  

Science.gov (United States)

This paper describes the acoustic properties of a range of epoxy resins prepared by photocuring that are suitable for application in piezoelectric ultrasonic transducer matching layers. Materials, based on blends of diglycidyl ether of Bisphenol A and 1,4-cyclohexanedimethanol diglycidyl ether, are described. Furthermore, in order to vary the elastic character of the base resin, samples containing polymer microspheres or barium sulfate particles are also described. The acoustic properties of the materials are determined by a liquid coupled through transmission methodology, capable of determining the velocity and attenuation of longitudinal and shear waves propagating in an isotropic layer. Measured acoustic properties are reported which demonstrate materials with specific acoustic impedance varying in the range 0.88-6.25 MRayls. In the samples comprising blends of resin types, a linear variation in the acoustic velocities and density was observed. In the barium sulfate filled samples, acoustic impedance showed an approximately linear variation with composition, reflecting the dominance of the density variation. While such variations can be predicted by simple mixing laws, relaxation and scattering effects influence the attenuation in both the blended and filled resins. These phenomena are discussed with reference to dynamic mechanical thermal analysis and differential scanning calorimetry of the samples. PMID:21110566

Trogé, Alexandre; O'Leary, Richard L; Hayward, Gordon; Pethrick, Richard A; Mullholland, Anthony J

2010-11-01

228

Modification of the structure and surface layer properties of hard magnetic materials with plasma processing  

International Nuclear Information System (INIS)

Processing of hard magnetic materials like Nd-Fe-B and Sm-Co with pulsed plasma streams gives the possibility to modify its physical and chemical properties considerably. In particular, in combination with deposition of protective coatings, the corrosion resistance can be essentially improved. Due to specific processes initiated by plasma treatment, such as fast heating and melting of surface layer with simultaneous penetration of ions of plasma streams to the material depth and following high-speed cooling (cooling rate ?10-6 K/c), effective modification of surface layer has been achieved. Features of pulsed plasma stream interaction with surface of the samples have been discussed. Controlled crystallization of amorphous alloys allows creation of new materials for producing permanent magnets. For this purpose it is important to form specific multiphase microstructure of alloy from the amorphous state. X-ray amorphous Nd2Fe23B3 phase has been synthesized as a result of the interaction of accelerated helium plasma streams with Nd8Fe87B5 alloy. Microstructure and composition of modified surface layer are examined. It is shown that integral content of elements have not been changed actually after plasma treatment. However distribution of constituent elements in the modified layer is not homogenous. Atoms in modified layer are redistributed diffusively due to the formation of domains (?50 nm) that are centers of crystallization of Nd2Fe23B3 phase. Nd atoms push off to the domains borders and form individual inclusions. Features of crystallization and formation of magnetic phases have been studied, optimal annealing conditions (temperature and time) have been determined. Optimal alloy composition with highest magnetic characteristics has been defined. Thermal stability tests of magnetic flux have been carried out also. Influence of deposited SiO2 protective coatings on corrosion resistance of hard-magnetic alloys has been studied. The tests were carried out by gravimetric method in the environment of distill water vapors of 100% humidity at room temperature. It was observed that uncoated samples after 48 hours testing had the trails of point corrosion and an average gain in weight was 0.120%. While deep red-brown encrustation are quickly developed on unprotected samples and substantial increase in weight after 120 hours of exposure is found, the coated samples show the first visual developments of corrosion only after 744 hours and the weigh gain did not exceed 0.02 % on average. Investigations of protective Ti coatings deposited with ECR plasma source have been performed also. Coating modification and mixing under the pulsed plasma processing are discussed. (author)

229

Electronic and material characterization of silicon-germanium and silicon-germanium-carbon epitaxial layers  

Science.gov (United States)

This dissertation presents results of material and electronic characterization of strained SiGe and SiGeC epitaxial layers grown on (100) silicon using Atmospheric Pressure Chemical Vapor Deposition and Reduced Pressure Chemical Vapor Deposition. Fabrication techniques for SiGe and SiGeC are also presented. Materials characterization of epitaxial SiGe and SiGeC was done to characterize crystallinity using visual, microscopic, and Rutherford Backscattering (RBS) characterization. Surface roughness was characterized and found to correspond roughly with epitaxial crystal quality. Spectroscopic ellipsometry was used to study epitaxial layer composition and thickness, requiring development of models for nSiGe and nSiGeC versus composition (the first published for nSiGeC) and generation of ellipsometric nomograms. X-ray diffraction (XRD) measurements of epitaxial strain and relaxation showed Ge composition dominates the stress, although strain compensation due to C was observed. XRD, Raman, and Fourier Transform Infrared (FTIR) characterization were done to characterize substitutional C in SiGeC epitaxial layers, finding that C incorporation into SiGeC saturates for C contents >1%. Fabrication techniques for SiGe and SiGeC were examined. Low thermal budget processing of strained layers were investigated as well as fabrication techniques using advantageous material properties of SiGe and SiGeC. Ti/Al contacts were developed and characterized for electrical contact to SiGe and SiGeC. Schottky contacts of Pt silicide on SiGe and SiGeC was done; formation and resistivity were characterized. Four separate resistivity characterization structures have been fabricated using mesa-etch and Si etch-stop techniques. A NPN Heterojunction Bipolar transistor has been fabricated using successive mesa-etches and SiGe (or SiGeC) etch-stops. Electronic characterization of in-situ doped SiGe and SiGeC epitaxial layers was done to determine resistivity, mobility, and bandgap. Resistivities were characterized using Four Point Probe (FPP), Spreading Resistance Profiling (SRP), and resistivity structures. Hall measurements on van der Pauw structures show mobility limiting mechanisms for electrons are similar to those for Si, while those for hole mobilities are quite different. Bandgap was characterized using Schottky barrier measurements and show Fermi pinning at 0.67eV for contacts to n-type. Schottky contacts p-type vary by composition and show the bandgap to decrease by 2.8meV per %Ge and increase by 15meV per %C.

Peterson, Jeffrey John

230

Complex layered materials and periodic electromagnetic band-gap structures: Concepts, characterizations, and applications  

Science.gov (United States)

The main objective of this dissertation is to characterize and create insight into the electromagnetic performances of two classes of composite structures, namely, complex multi-layered media and periodic Electromagnetic Band-Gap (EBG) structures. The advanced and diversified computational techniques are applied to obtain their unique propagation characteristics and integrate the results into some novel applications. In the first part of this dissertation, the vector wave solution of Maxwell's equations is integrated with the Genetic Algorithm (GA) optimization method to provide a powerful technique for characterizing multi-layered materials, and obtaining their optimal designs. The developed method is successfully applied to determine the optimal composite coatings for Radar Cross Section (RCS) reduction of canonical structures. Both monostatic and bistatic scatterings are explored. A GA with hybrid planar/curved surface implementation is also introduced to efficiently obtain the optimal absorbing materials for curved structures. Furthermore, design optimization of the non-uniform Luneburg and 2-shell spherical lens antennas utilizing modal solution/GA-adaptive-cost function is presented. The lens antennas are effectively optimized for both high gain and suppressed grating lobes. The second part demonstrates the development of an advanced computational engine, which accurately computes the broadband characteristics of challenging periodic electromagnetic band-gap structures. This method utilizes the Finite Difference Time Domain (FDTD) technique with Periodic Boundary Condition/Perfectly Matched Layer (PBC/PML), which is efficiently integrated with the Prony scheme. The computational technique is successfully applied to characterize and present the unique propagation performances of different classes of periodic structures such as Frequency Selective Surfaces (FSS), Photonic Band-Gap (PBG) materials, and Left-Handed (LH) composite media. The results are incorporated into some novel applications such as high Q nanocavity lasers, guiding the electromagnetic waves at sharp bends, and miniaturized microstrip patch antennas.

Mosallaei, Hossein

231

Sacrificial anode retrofits: Innovative solutions for the challenge of deepwater and other complex marine environments  

Energy Technology Data Exchange (ETDEWEB)

Offshore oil and gas platforms, pipelines and marine structures are most often cathodically protected with sacrificial anodes, which require periodic replacement. Rising costs associated with traditional diver-placed retrofits have necessitated development of surface and remotely operated vehicle (R.O.V.) deployed systems. Innovations in mounting hardware have also been developed for more rapid installation of diver-placed anodes.

Brandt, J.A. [Corrtherm, Inc., Belle Chasse, LA (United States)

1997-09-01

232

46 CFR 35.01-25 - Sacrificial anode installations-TB/ALL.  

Science.gov (United States)

...sacrificial anodes in cargo tanks utilized for the carriage...be permitted in cargo tanks under the following criteria...above the bottom of the tank. Special consideration...given when structural design prevents the anodes...installation and a chemical analysis of the alloy...

2010-10-01

233

Work function and electron affinity of some layered transition metal dichalcogenide materials  

International Nuclear Information System (INIS)

Work function and electron affinity values of various semiconducting and metallic layered transition metal dichalcogenides (TMDCs) which might be suitable for the photovoltaic applications (such as ZrSxSe2-x where 0?x?2, HfSe2, HfS2, TiTe2, NbTe2, TaS2) have been measured using photoemission spectroscopy and vibrating capacitor Kelvin probe techniques. All samples were single crystals grown by the chemical vapour transport method with iodine as a transport agent. The measured values are compared to the previously reported empirical and calculated values based on various band models, and proved good agreement for most of the materials.

234

Production of layered zirconium-steel composite materials by solid-phase welding  

International Nuclear Information System (INIS)

The method of solid-phase welding is applied to produce layered composite materials on the basis of zirconium and stainless steel type 12Kh18N10T with niobium and copper interlayers used in nuclear reactor fuel elements as well as in control devices with nondetachable joints. It is shown that adhesion joints of zirconium and steel obtained by vacuum hot rolling possess high stability under conditions of thermal cycling and alternating loading. A correlation is established between structural changes in the composite and its softening under thermal cycling within the range of 200-800 deg C

235

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

236

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

237

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)

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

Zheng LU

2014-12-01

238

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

Science.gov (United States)

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.

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

2005-09-01

239

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.

240

Optimizing a Portable Microwave Interference Scanning System for Nondestructive Testing of Multi-Layered Dielectric Materials  

Science.gov (United States)

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.

Schmidt, K. F.; Little, J. R.; Ellingson, W. A.; Green, W.

2010-02-01

241

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

242

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

DEFF Research Database (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.

Jessen, Bjarke SØrensen Technical University of Denmark,

243

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

Directory of Open Access Journals (Sweden)

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

Sergey F. Filonenko

2008-02-01

244

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

Science.gov (United States)

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 cm(2)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 10(5), a field-effect mobility of 205 cm(2)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. PMID:25041752

Xia, Fengnian; Wang, Han; Jia, Yichen

2014-01-01

245

Characterization of Elastic-plastic Material Properties for IMC Layer of ENEPIG by Using Reverse Algorithm  

Science.gov (United States)

Recently, the reliability assurance of lead-free solder to prevent environmental contamination is quite important issue for chip-scale packaging. Although lots of efforts have been devoted to the solder undergone drop, shear and creep loads, there was a little research on IMC due primarily to its thickness restriction and geometric irregularity. However, the IMC is known as the weakest layer governing failures of the solder joint. The present work is to characterize realistic material properties of the IMC for ENEPIG process. Lee's modified reverse algorithm was adopted to determine elastic-plastic stress-strain curve and so forth, after examining several methods, which requires inherently elastic data. In this context, a series of nano-indentation tests as well as corresponding simulations were carried out by changing indentation depths from 200 to 400 nm and strain rates from 0.05 to 0.10 1/s. It would be conclude that effect of strain rate is relatively small and IMC layer should be more than 5 times of indentation depth when using the recommended method, which are applicable to generate realistic material properties for further diverse structural integrity simulations.

Kim, Jong-Min; Lee, Hyun-Boo; Chang, Yoon-Suk; Choi, Jae-Boong; Kim, Young-Jin; Ji, Kum-Young

2010-05-01

246

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

Science.gov (United States)

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.

Xia, Fengnian; Wang, Han; Jia, Yichen

2014-07-01

247

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

Directory of Open Access Journals (Sweden)

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.

XIAOQIAN LIU

2010-12-01

248

Imaging Fourier transform spectroscopy of the boundary layer plume from laser irradiated polymers and carbon materials  

Science.gov (United States)

The high-energy laser (HEL) lethality community needs for enhanced laser weapons systems requires a better understanding of a wide variety of emerging threats. In order to reduce the dimensionality of laser-materials interaction it is necessary to develop novel predictive capabilities of these events. The objective is to better understand the fundamentals of laser lethality testing by developing empirical models from hyperspectral imagery, enabling a robust library of experiments for vulnerability assessments. Emissive plumes from laser irradiated fiberglass reinforced polymers (FRP), poly(methyl methacrylate) (PMMA) and porous graphite targets were investigated primarily using a mid-wave infrared (MWIR) imaging Fourier transform spectrometer (FTS). Polymer and graphite targets were irradiated with a continuous wave (cw) fiber lasers. Data was acquired with a spectral resolution of 2 cm-1 and spatial resolution as high as 0.52 mm2 per pixel. Strong emission from H2O, CO, CO2 and hydrocarbons were observed in the MWIR between 1900-4000 cm-1. A single-layer radiative transfer model was developed to estimate spatial maps of temperature and column densities of CO and CO2 from the hyperspectral imagery of the boundary layer plume. The spectral model was used to compute the absorption cross sections of CO and CO2, using spectral line parameters from the high temperature extension of the HITRAN. Also, spatial maps of gas-phase temperature and methyl methacrylate (MMA) concentration were developed from laser irradiated carbon black-pigmented PMMA at irradiances of 4-22 W/cm2. Global kinetics interplay between heterogeneous and homogeneous combustion kinetics are shown from experimental observations at high spatial resolutions. Overall the boundary layer profile at steady-state is consistent with CO being mainly produced at the surface by heterogeneous reactions followed by a rapid homogeneous combustion in the boundary layer towards buoyancy.

Acosta, Roberto I.

249

Emergency sacrificial sealing method in filters, equipment, or systems  

Science.gov (United States)

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.

Brown, Erik P

2014-09-30

250

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

Energy Technology Data Exchange (ETDEWEB)

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)

Inoue, Kazuko; Tsujikami, Tetsuya; Ohyanagi, Manshi [Ryukoku Univ., Faculty of Science and Technology, Otsu, Shiga (JP)] (and others)

2003-03-01

251

Thermal response of infinitely extended layered nickel-titanium shape memory alloy thin film with variable material properties  

Science.gov (United States)

This paper reports a study of the thermal response of an infinitely extended shape memory alloy thin film. Motivated by experiments reported in the literature about SMA thin films on a silicon substrate, the thin film is taken to have three layers from the bottom to the top - an amorphous layer, a non-transforming austenitic layer and a transforming SMA layer. The boundary conditions are taken to be adiabatic and convective at the bottom of the film and the top respectively. The material properties of the transforming layer (thermal conductivity, electrical resistivity and specific heat) are taken to evolve hysteretically with temperature, commencing from an initial room temperature state of martensite. All the results are presented in non-dimensional form. The steady state results are compared with an analytical solution. The computations of the transient response are carried out with ANSYS. The thermal response of the 3-layer model is compared with that of a 1-layer model (where the entire film is a SMA transforming layer) and it is seen that the the temperature of the top surface for the 3-layer model is higher than that of the 1-layer model. It is also seen that the evolution of the specific heat has the least effect whereas the evolution of the electrical resistivity has the most effect on the thermal response of the 3-layer model. The thermal response of the infinitely extended films provides a benchmark against which the response of finite sized films can be assessed.

Bhattacharyya, Abhijit; Ozturk, Mehmet Mete

2013-04-01

252

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

Directory of Open Access Journals (Sweden)

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.

Ludovic F. Dumee

2014-08-01

253

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

254

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

Science.gov (United States)

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 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.

Yamamoto, H.; Nomachi, M.; Yasuda, K.; Iwami, Y.; Ebisu, S.; Komatsu, H.; Sakai, T.; Kamiya, T.

2007-07-01

255

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

256

Experimental Study on Intermediate Layer Made of (0-3) Composite Materials for Use in Air-Coupled Ultrasonic Transducers  

Science.gov (United States)

The (0-3) composite materials for the intermediate layer of a MHz-range air-coupled ultrasonic transducer were studied experimentally. The optimal value of the characteristic acoustic impedance for this intermediate layer was calculated using a transmission line model. The (0-3) composite materials were formed from a mixture of silicone rubber and hollow thermoplastic microspheres at various weight ratios, and their acoustic properties were measured, and compared with those of a Reuss model. The measured values of the acoustic properties of the composite materials agreed well with the theoretical estimation. The transmission and reception of an air-coupled ultrasonic waves of 1 MHz using a piezoceramic transducer fitted with the intermediate layer was demonstrated with a pulse-echo system, and the sensitivity was improved by 20 dB by using the optimal composite material.

Saito, Kazuki; Nishihira, Morimasa; Imano, Kazuhiko

2007-07-01

257

Synthesis, structural and spectroscopic properties of two new ethylenediamine-templated gallophosphate-oxalate layered materials.  

Science.gov (United States)

Two new layered gallophosphate-oxalate materials have been prepared hydrothermally using ethylenediamine and oxalic acid as structure-directing agents. The compounds (C2N2H10)2[Ga2(C2O4)2(HPO4)3].H2O 1 and (C2N2H10)3- [Ga4(C2O4)4(HPO4)4(H2PO4)2] 2 are closely related, consisting of anionic double chains built of alternating paris of GaO6 and HPO4 polyhedra. These double chains are linked via bridging HPO4 or H2PO4 tetrahedra to form corrugated layers containing eight-membered rings. The oxalate group acts as a bidentate ligand to each of the GaO6 octahedron. The corrugated layers are held together by strong to weak hydrogen-bonding interactions between oxalate groups, water and diprotonated ethylenediamine molecules, and the framework components. The compounds were characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and infrared and Raman spectroscopy. Crystal data for 1: monoclinic, space group P21/C (No. 14), a = 6.355(1) A, b = 39.362(8) A, c = 9.249(2) A, beta = 106.7(1) degrees, Z = 2. Crystal data for 2: triclinic, space group P1 (No. 2), a = 8.730(1) A, b = 11.575(1) A, c = 11.696(1) A, alpha = 115.12(1) degree, beta = 90.07(1) degree, gamma = 111.23(1) degree, Z = 2. PMID:12693244

Mrak, Maja; Kolitsch, Uwe; Lengauer, Christian; Kaucic, Venceslav; Tillmanns, Ekkehart

2003-01-27

258

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

Science.gov (United States)

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

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

2015-04-21

259

The thin electrolyte layer approach to corrosion testing of dental materials--characterization of the technique.  

Science.gov (United States)

An innovative technique for corrosion testing of metallic dental materials is introduced. The thin electrolyte layer technique (TET) simulates the physical characteristics of the oral environment by employing a still, thin layer of an electrolyte, in contrast to bulk electrolyte techniques (BET) which utilize relatively large quantities of fluid. Limiting current density tests on a platinum electrode revealed a lower surface oxygen content for TET. Borate buffer (pH 6.8) was employed as an electrolyte. The effect of lower oxygen content in TET on passivation and polarization characteristics of 316L SS in 0.9% saline was investigated. The results revealed differences in the polarization resistance and open circuit potential development with time, as well as in anodic and cathodic polarization behavior. Lower O2 concentration in TET was attributed to different electrolyte convection characteristics under both testing conditions. Additionally, use of the TET resulted in better data reproducibility. Overall, this investigation led to a deeper understanding of the electrochemical processes inherent in thin electrolytes such as those found in the oral environment. PMID:9884061

Ledvina, M; Rigney, E D

1998-12-01

260

SeP hole injection layer for devices based on organic materials  

Science.gov (United States)

Selenium?:?phosphour (SeP) thin films produced by thermal sublimation in vacuum are used as hole injection layers (HILs) in tris(8-hydroxyquinolinato) aluminum (Alq3) based devices. These devices are constructed in the sandwich structure substrate/HIL/Alq3/Al using three different substrate electrodes: fluorine doped tin oxide, Au, and indium tin oxide. The obtained electrical measurements indicate a better injection of positive charge carriers using the SeP layer. Syncrotron radiation x-ray photoelectron experiments allowed the determination of the work function of SeP. The obtained value (? = 5.6 eV) is close to the HOMO energy level of Alq3 and is consistent with the better positive charge injection. The thermionic injection process is suggested to be responsible for the charge injection from the different substrate electrodes into the SeP material. From transmittance measurements it was possible to calculate the refractive index and absorption coefficient as a function of wavelength, and to estimate the optical band gap (Eg = 1.9 eV). The latter and the measured work function were used in the construction of an energy level diagram of the SeP thin films used as HILs in organic devices. The hole injection efficiency of the produced films are compared with results using poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT?:?PSS).

Serbena, J. P. M.; Machado, K. D.; Siqueira, M. C.; Hümmelgen, I. A.; Mossanek, R. J. O.; de Souza, G. B.; da Silva, J. H. D.

2014-01-01

261

Periodic materials-based vibration attenuation in layered foundations: experimental validation  

International Nuclear Information System (INIS)

Guided by the recent advances in solid-state research in periodic materials, a new type of layered periodic foundation consisting of concrete and rubber layers is experimentally investigated in this paper. The distinct feature of this new foundation is its frequency band gaps. When the frequency contents of a wave fall within the range of the frequency band gaps, the wave, and hence its energy, will be weakened or cannot propagate through the foundation, so the foundation itself can serve as a vibration isolator. Using the theory of elastodynamics and the Bloch–Floquet theorem, the mechanism of band gaps in periodic composites is presented, and a finite element model is built to show the isolation characteristic of a finite dimensional periodic foundation. Based on these analytical results, moreover, a scaled model frame and a periodic foundation were fabricated and shake table tests of the frame on the periodic foundation were performed. Ambient, strong and harmonic vibration attenuations are found when the exciting frequencies fall into the band gaps. (fast track communication)

262

Water management in a PEMFC: water transport mechanism and material degradation in gas diffusion layers  

Energy Technology Data Exchange (ETDEWEB)

It has now been well recognized that both the performance and durability of proton exchange membrane fuel cells (PEMFCs) are closely related to the water accumulation and transport inside its porous components, particularly in the gas diffusion layer (GDL), and microporous layer (MPL). In this paper, the key GDL and MPL properties that affect water transport through them are first discussed and a review of GDL degradation mechanisms is presented. An intermittent water drainage mechanism across the GDL is discussed. The capillary breakthrough pressure (CBP) and the dynamic capillary pressure (DCP), or recurrent breakthrough dynamics, have been identified as key GDL properties that affect its water management performance and function as indicators of the degradation of GDL material. This work uses a novel ex situ experiment to degrade a GDL by exposing it to an accelerated stress test (AST) that subjects the GDL to elevated operation conditions seen at the cathode side of a PEMFC for an extended period of time. In turn, the effect of the AST on the CBP and DCP is investigated. As a result, a loss of hydrophobicity occurred on the MPL surface. This altered the CBP and DCP, thus decreasing water management in the GDL. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Kandlikar, S.G.; Garofalo, M.L.; Lu, Z. [Department of Mechanical Engineering, Rochester Institute of Technology, 76 Lomb Memorial Drive, Rochester, NY 14623 (United States)

2011-12-15

263

SeP hole injection layer for devices based on organic materials  

International Nuclear Information System (INIS)

Selenium?:?phosphour (SeP) thin films produced by thermal sublimation in vacuum are used as hole injection layers (HILs) in tris(8-hydroxyquinolinato) aluminum (Alq3) based devices. These devices are constructed in the sandwich structure substrate/HIL/Alq3/Al using three different substrate electrodes: fluorine doped tin oxide, Au, and indium tin oxide. The obtained electrical measurements indicate a better injection of positive charge carriers using the SeP layer. Syncrotron radiation x-ray photoelectron experiments allowed the determination of the work function of SeP. The obtained value (? = 5.6 eV) is close to the HOMO energy level of Alq3 and is consistent with the better positive charge injection. The thermionic injection process is suggested to be responsible for the charge injection from the different substrate electrodes into the SeP material. From transmittance measurements it was possible to calculate the refractive index and absorption coefficient as a function of wavelength, and to estimate the optical band gap (Eg = 1.9 eV). The latter and the measured work function were used in the construction of an energy level diagram of the SeP thin films used as HILs in organic devices. The hole injection efficiency of the produced films are compared with results using poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT?:?PSS). (paper)

264

Thermophysical properties of Alaskan loess: An analog material for the Martian polar layered terrain?  

Science.gov (United States)

The Martian surface has several regions where thermal inertia measurements indicate a porous ice-free insulating surface, yet are mechanically competent enough to sustain substantial slopes. In support of the interpretation of those regions within the Martian polar layered terrain, we report measurements of thermal conductivity for loess from the field and in the USA CRREL Permafrost Tunnel. Permafrost Tunnel loess is a desiccated material that can form vertical walls, but is of low density (800-1000 kg/m³), modest shear strength (4 kPa), and has a low thermal conductivity (0.1 W/m-K at 1 bar). These properties are similar to the inferred properties of the Martian polar layered terrain. The Birch Hill field sample has a density of 1160 kg/m³ and a conductivity of 0.15 W/m-K. The Chena Spur Road sample has a density of 1360 kg/m³ and a conductivity of 0.7 W/m-K. The relatively high conductivity for the Chena Spur Road is due to the cementation of soil grain contacts, its higher density, coarser grain size, and higher quartz grain content.

Johnson, Jerome B.; Lorenz, Ralph D.

2000-09-01

265

New magnetic materials obtained by ion-exchange reactions from non-magnetic layered perovskites  

Science.gov (United States)

New layered magnetic materials, (MCl)Ca2Ta3O10 (M = Cu, Fe), have been prepared by ion-exchange reactions of non-magnetic perovskite derivatives, ACa2Ta3O10 (A = Rb, Li), in corresponding anhydrous molten salts. Powder x-ray diffraction patterns of the products are successfully indexed assuming tetragonal symmetry with cell dimensions a = 3.829 Å and c = 15.533 Å for Cu, and a = 3.822 Å and c = 15.672 Å for Fe. Being separated by the Ca2Ta3O10 triple-layer perovskite slabs, the transition-metal chloride (MCl) network provides a two-dimensional magnetic lattice. Magnetic susceptibility measurements show that (CuCl)Ca2Ta3O10 is in an antiferromagnetic state below 8 K, while (FeCl)Ca2Ta3O10 has two anomalies at 91 and 125 K, suggesting successive phase transitions due to geometrical spin frustration.

Kageyama, H.; Viciu, L.; Caruntu, G.; Ueda, Y.; Wiley, J. B.

2004-03-01

266

New magnetic materials obtained by ion-exchange reactions from non-magnetic layered perovskites  

Energy Technology Data Exchange (ETDEWEB)

New layered magnetic materials (MCl)Ca{sub 2}Ta{sub 3}O{sub 10} (M = Cu, Fe), have been prepared by ion-exchange reactions of non-magnetic perovskite derivatives, ACa{sub 2}Ta{sub 3}O{sub 10} (A = Rb, Li), in corresponding anhydrous molten salts. Powder x-ray diffraction patterns of the products are successfully indexed assuming tetragonal symmetry with cell dimensions a = 3.829 A and c = 15.533 A for Cu, and a = 3.822 A and c = 15.672 A for Fe. Being separated by the Ca{sub 2}Ta{sub 3}O{sub 10} triple-layer perovskite slabs, the transition-metal chloride (MCl) network provides a two-dimensional magnetic lattice. Magnetic susceptibility measurements show that (CuCl)Ca{sub 2}Ta{sub 3}O{sub 10} is in an antiferromagnetic state below 8 K, while (FeCl)Ca{sub 2}Ta{sub 3}O{sub 10} has two anomalies at 91 and 125 K, suggesting successive phase transitions due to geometrical spin frustration.

Kageyama, H [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Viciu, L [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States); Caruntu, G [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States); Ueda, Y [Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 (Japan); Wiley, J B [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States)

2004-03-24

267

New magnetic materials obtained by ion-exchange reactions from non-magnetic layered perovskites  

International Nuclear Information System (INIS)

New layered magnetic materials (MCl)Ca2Ta3O10 (M = Cu, Fe), have been prepared by ion-exchange reactions of non-magnetic perovskite derivatives, ACa2Ta3O10 (A = Rb, Li), in corresponding anhydrous molten salts. Powder x-ray diffraction patterns of the products are successfully indexed assuming tetragonal symmetry with cell dimensions a = 3.829 A and c = 15.533 A for Cu, and a = 3.822 A and c = 15.672 A for Fe. Being separated by the Ca2Ta3O10 triple-layer perovskite slabs, the transition-metal chloride (MCl) network provides a two-dimensional magnetic lattice. Magnetic susceptibility measurements show that (CuCl)Ca2Ta3O10 is in an antiferromagnetic state below 8 K, while (FeCl)Ca2Ta3O10 has two anomalies at 91 and 125 K, suggesting successive phase transitions due to geometrical spin frustration

268

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

OpenAIRE

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 toug...

Jia Yao; Ying Cheng Hu,; Wei Lu

2011-01-01

269

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)

270

CDR 1 shielding mortar and the filling of sacrificial shields of Alto Lazio nuclear power station  

International Nuclear Information System (INIS)

The use of mortars for shelding needs in place of heavy concrete or metals was growing in the last fifteen years. The reason is they are easy to use in applications where the shilding or the technological requirement are severe or construction field asks for peculiar devices. Mortar emploied in the filling of the central part of the Alto Lazio 1 and 2 Sacrificial Shields was studied and produced by Nuclear Protection, with the continuous surveillance by ENEL, CCN, and ENEA. The qualification required a long sequence of analyses and experimental tests. In the report are indicated the characteristics of the CDR 1 mortar, with the technical and the QC requirements, the technological tests, the neutron and gamma attenuation tests and the thermogravimetric tests performed; the filling of a 1:1 scale moke-up, and finally the filling of the two A.L. sacrificial shields

271

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

272

Tube Formation in Nanoscale Materials  

Directory of Open Access Journals (Sweden)

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.

Yan Chenglin

2008-01-01

273

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.

274

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

Directory of Open Access Journals (Sweden)

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.

Yongxun Liu

2014-06-01

275

Multiple layers of self-asssembled Ge/Si islands: Photoluminescence, strain fields, material interdiffusion, and island formation  

International Nuclear Information System (INIS)

Strain fields in stacked layers of vertically aligned self-assembled Ge islands on Si(100) can cause a reduction of the wetting layer thickness in all but the initial layer and hence induce an energy separation ?Ewl between the energy transitions of the different wetting layers. Our systematic photoluminescence (PL) study on twofold stacked Ge/Si layers shows that the quantity ?Ewl is a sensitive function of the Si spacer thickness and reflects the degree of strain field interaction between the island layers. Pronounced PL blueshifts are also observed for the island related energy transition in twofold and multifold island layers. We suggest that with increasing number of stacked island layers strain field superposition of buried islands causes enhanced SiGe material intermixing during Si overgrowth of the islands. This effect naturally explains the strong PL blueshift of the island related energy transition. Recently observed shape transformations in stacked Ge islands are well explained by our model of superimposed strain fields. We also discuss the initial stages of island formation in the second Ge layer of twofold island stacks. Many of the effects observed in this paper on the Ge/Si system are probably also important for self-assembling III/V islands but due to extremely small sizes are much harder to evaluate

276

Interlayer material transport during layer-normal shortening. Part I. The model  

OpenAIRE

To analyse mass-transfer during deformation, the case is considered of a multilayer experiencing a layer-normal shortening that is volume constant on the scale of many layers. Strain rate is homogeneously distributed on the layer-scale if diffusion is absent; when transport of matter between the layers occurs, strain rate and dilatation rate are found to vary with distance from the contacts between layers. An instantaneous model for differentiation is developed on the assumption that the sole...

Molen, I.

1985-01-01

277

Intercalation of polyethylene oxide PEO in layered MPS3 (M = Ni, Fe) materials  

International Nuclear Information System (INIS)

The intercalation compounds Li0.96(H2O)0.77(PEO)0.63Ni0.48PS3 and Li0.94(H2O)0.92(PEO)0.94Fe0.48PS3 obtained by the insertion of PEO in MPS3 form lithium-polyethylene oxide complexes containing Li+ exchangeable cation in the interlayer space. Polyethylene oxide (PEO) is able to associate interlayer cation increasing the ionic conductivity of NiPS3 and FePS3. These compounds constitute a new family of intercalates MPS3 (M = Ni, Fe) host-layer materials. The new materials were characterized by powder X-Ray diffraction (XRD), Fourier-transformed infrared (FT-IR), differential thermal and thermogravimetric analyses (DTA/TG), energy dispersive X-Ray (EDX), inductively coupled plasma (ICP) and electrochemical impedance measurements. The intercalation compound Li0.96(H2O)0.77(PEO)0.63Ni0.48PS3 shows an ionic conductivity of 0.13 ?S/cm, and dc electronic conductivity of ca. 0.1 ?S/cm which is twice that of NiPS3

278

Laser etching of transparent materials at a backside surface adsorbed layer  

International Nuclear Information System (INIS)

The laser etching using a surface adsorbed layer (LESAL) is a new method for precise etching of transparent materials with pulsed UV-laser beams. The influence of the processing parameters to the etch rate and the surface roughness for etching of fused silica, quartz, sapphire, and magnesium fluoride (MgF2) is investigated. Low etch rates of 1 nm/pulse and low roughness of about 1 nm rms were found for fused silica and quartz. This is an indication that different structural modifications of the material do not affect the etching significantly as long as the physical properties are not changed. MgF2 and sapphire feature a principal different etch behavior with a higher etch rate and a higher roughness. Both incubation effects as well as the temperature dependence of the etch rate can be interpreted by the formation of a modified near surface region due to the laser irradiation. At repetition rates up to 100 Hz, no changes of the etch rate have been observed at moderate laser fluences

279

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

280

Processing of Nanosensors Using a Sacrificial Template Approach  

Science.gov (United States)

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

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

2012-01-01

281

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

Science.gov (United States)

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.

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

2014-10-01

282

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

283

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

Science.gov (United States)

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.

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

2013-10-01

284

Design, materials and R and D issues of innovative thermal contact joints for high heat flux applications  

International Nuclear Information System (INIS)

Plasma facing components in fusion machines are designed with a layer of sacrificial armour material facing the plasma and a high-conductivity material in contact with the coolant. One of the most critical issues associated with making the proposed design concept work, from a power handling point of view, is achieving the necessary contact conductance between the armour and the heat sink.This paper presents a novel idea for the interface joint between the sacrificial armour and the actively cooled permanent heat sink. It consists of a thermal bond layer of a binary or more complex alloy, treated in the semi-solid region in such a way as to lead to a fine dispersion of a globular solid phase into a liquid matrix (rheocast process). The alloy in this ''mushy state'' exhibits a time-dependent, shear rate-dependent viscosity, which is maintained reversibly when the material is solidified and heated again in the semi-solid state. The function of the thermal bond layer is to facilitate heat transfer between the replaceable armour and the permanent heat sink without building up excessive thermal stresses, as in conventional brazed joints, and allow an easy replacement whenever needed without disturbing the coolant system. No contact pressure is required in this case to provide the desired heat transfer conductance, and the reversible thixotropic properties of the rheocast material should guarantee the stability of the layer in the semi-solid conditions.Key design, material ami-solid conditions.Key design, material and testing issues are identified and discussed in this paper with emphasis on specific needs for future research and development work. Examples of suitable material options which are being considered are reported together with some initial heat transfer analysis results. (orig.)

285

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)

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.

FLORENTINA TOCU

2012-12-01

286

Atomic layer deposition of HfxAlyCz as a work function material in metal gate MOS devices  

International Nuclear Information System (INIS)

As advanced silicon semiconductor devices are transitioning from planar to 3D structures, new materials and processes are needed to control the device characteristics. Atomic layer deposition (ALD) of HfxAlyCz films using hafnium chloride and trimethylaluminum precursors was combined with postdeposition anneals and ALD liners to control the device characteristics in high-k metal-gate devices. Combinatorial process methods and technologies were employed for rapid electrical and materials characterization of various materials stacks. The effective work function in metal–oxide–semiconductor capacitor devices with the HfxAlyCz layer coupled with an ALD HfO2 dielectric was quantified to be mid-gap at ?4.6?eV. Thus, HfxAlyCz is a promising metal gate work function material that allows for the tuning of device threshold voltages (Vth) for anticipated multi-Vth integrated circuit devices

287

Double-layer type microwave absorber made of magnetic-dielectric composite material  

Energy Technology Data Exchange (ETDEWEB)

Changing the combination of 2{sup nd} layer in a double-layer type microwave absorber, the matching frequency (8.10-10.88 GHz), maximum reflection loss and matching thickness at the matching frequency could be systematically controlled and compared with those of single-layer type microwave absorber. (orig.)

Saitoh, M.; Yamamoto, T.; Okino, H.; Chino, M. [Department of Communications Engineering, National Defense Academy, Yokosuka (Japan); Kobayashi, M. [Tayca Co. Osaka Laboratory, Osaka (Japan)

2002-04-01

288

Thermal Stability of Gold Nanoparticles Embedded within Metal Oxide Frameworks Fabricated by Hybrid Modifications onto Sacrificial Textile Templates.  

Science.gov (United States)

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

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

2015-01-27

289

Atomic layer deposition of organic-inorganic hybrid materials based on saturated linear carboxylic acids.  

Science.gov (United States)

Atomic layer deposition (ALD) has successfully provided thin films of organic-inorganic hybrid materials based on saturated linear carboxylic acids and trimethylaluminium (TMA). Films were grown for seven carboxylic acids: oxalic, malonic, succinic, glutaric, pimelic, suberic and sebacic acid, i.e. ranging from 2 to 10 carbon atoms in the molecular structure. These processes show exceptionally high growth rates; up to 4.3 nm/cycle for the pimelic acid-TMA system. Quartz crystal microbalance measurements of the growth dynamics indicate that all systems are of a self limiting ALD-type. Nevertheless, temperature dependent growth was observed in several systems. The width of the ALD windows shows correlations with the length of the carbon chains. Fourier transform infrared spectroscopy clearly proved that the deposited films are of a hybrid character, where the carboxylic acids primarily form bidentate complexes, though bridging complexes may also form. All films are X-ray amorphous as deposited. The films were further analyzed by atomic force microscopy for surface roughness and topography, UV-Vis spectroscopy and ellipsometry for optical properties, and the goniometer method for measuring sessile drops for surface wetting properties. Apart from the oxalic and malonic acid-TMA systems, the films are stable in contact with water. The films are generally smooth, transparent and have a refractive index close to 1.5. The complete coverage and accurate growth control offered by the ALD technique is here proven to provide surface-functionalized hybrid materials resembling metal-organic frameworks (MOF), probably as rather dense structures, yet with substantial potential for applications. PMID:21442116

Klepper, Karina Barnholt; Nilsen, Ola; Hansen, Per-Anders; Fjellvåg, Helmer

2011-05-01

290

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.

291

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

Energy Technology Data Exchange (ETDEWEB)

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 Si{sub 2}H{sub 6} and WF{sub 6} reactants at 200 Degree-Sign 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 Degree-Sign 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).

Mane, Anil U.; Greene, John P.; Nolen, Jerry A. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Sampathkumaran, Uma; Owen, Thomas W.; Winter, Ray [InnoSence LLC, 2531 West 237 Street, Torrance, CA 90505 (United States); Elam, Jeffrey W., E-mail: jelam@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

2012-06-15

292

Atomic layer deposited molybdenum nitride thin film: a promising anode material for Li ion batteries.  

Science.gov (United States)

Molybdenum nitride (MoNx) thin films are deposited by atomic layer deposition (ALD) using molybdenum hexacarbonyl [Mo(CO)6] and ammonia [NH3] at varied temperatures. A relatively narrow ALD temperature window is observed. In situ quartz crystal microbalance (QCM) measurements reveal the self-limiting growth nature of the deposition that is further verified with ex situ spectroscopic ellipsometry and X-ray reflectivity (XRR) measurements. A saturated growth rate of 2 Å/cycle at 170 °C is obtained. The deposition chemistry is studied by the in situ Fourier transform infrared spectroscopy (FTIR) that investigates the surface bound reactions during each half cycle. As deposited films are amorphous as observed from X-ray diffraction (XRD) and transmission electron microscopy electron diffraction (TEM ED) studies, which get converted to hexagonal-MoN upon annealing at 400 °C under NH3 atmosphere. As grown thin films are found to have notable potential as a carbon and binder free anode material in a Li ion battery. Under half-cell configuration, a stable discharge capacity of 700 mAh g(-1) was achieved after 100 charge-discharge cycles, at a current density of 100 ?A cm(-2). PMID:24641277

Nandi, Dip K; Sen, Uttam K; Choudhury, Devika; Mitra, Sagar; Sarkar, Shaibal K

2014-05-14

293

Crystal Chemical Concept of Arrangement and Function of Layered Superconducting Materials  

CERN Document Server

The crystal chemical concept of arrangement and function of layered superconducting materials is supposed. The concept is based on results of our investigation of crystal chemistry of HTSC cuprates, diborides AB2 and borocarbides of nickel RNi2B2C. According to these results: (1) the main role in appearance of superconductivity play the structural fragments - sandwiches A2(CuO2) in HTSC cuprates, A2(B2) in diborides and RB(Ni) in nickel borocarbides but not the separate planes of CuO2, B2 or Ni; (2) correlations between Tc and crystal chemical parameters of these sandwiches have similar character in all three classes of compounds, despite of distinction of a nature of their superconductivity. The central idea of concept consists in following: in contrast to metallic conduction, for which it is enough to provide only concentration and mobility of charge carriers, for occurrence of a superconductivity it is necessary to create in addition a space (channels) for stream of charge carriers, compression of stream o...

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

2003-01-01

294

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).

295

Excellent performance of few-layer borocarbonitrides as anode materials in lithium-ion batteries.  

Science.gov (United States)

Borocarbonitrides (BxCyNz) with a graphene-like structure exhibit a remarkable high lithium cyclability and current rate capability. The electrochemical performance of the Bx Cy Nz materials, synthesized by using a simple solid-state synthesis route based on urea, was strongly dependent on the composition and surface area. Among the three compositions studied, the carbon-rich compound B0.15C0.73N0.12 with the highest surface area showed an exceptional stability (over 100 cycles) and rate capability over widely varying current density values (0.05-1 A g(-1)). B0.15C0.73N0.12 has a very high specific capacity of 710 mA h g(-1) at 0.05 A g(-1) . With the inclusion of a suitable additive in the electrolyte, the specific capacity improved drastically, recording an impressive value of nearly 900 mA h g(-1) at 0.05 A g(-1) . It is believed that the solid-electrolyte interphase (SEI) layer at the interface of BxCyNz and electrolyte also plays a crucial role in the performance of the BxCyNz . PMID:24151029

Sen, Sudeshna; Moses, Kota; Bhattacharyya, Aninda J; Rao, C N R

2014-01-01

296

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

Science.gov (United States)

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.

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

2010-07-27

297

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

International Nuclear Information System (INIS)

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

298

Application of the thin electrolyte layer technique to corrosion testing of dental materials  

Science.gov (United States)

Proper simulation of the oral environment for the corrosion testing of dental materials is crucial for determining corrosion rates and mechanisms correctly. In this study, the thin electrolyte layer technique (TET) was characterized and employed to investigate the importance of the chemical composition of the testing environment on the outcome of electrochemical tests. The thickness of the electrolyte layer in TET is only 0.5 mm and contains only 20 muL of electrolyte. This arrangement simulates the physical characteristics of the oral environment and facilitates testing in human saliva. Oxygen availability for reduction on the sample surface was determined, using cathodic polarization of Pt in borate buffer, to be lower in TET than in traditional (bulk electrolyte) techniques. Appreciable differences were found during polarization experiments on 316 L SS in saline and artificial saliva. Oxygen content was found to play a significant role in the corrosivity of various species contained in artificial saliva. Potentiodynamic polarization employing human saliva in TET on 316L SS proved to be very different from tests performed in artificial saliva. This was believed to be due to the presence of organic species, specifically proteins, contained in human saliva. This was further confirmed by cyclic polarization and corrosion current measurements of four commercial nickel-chromium (NiCr) alloys with varying amounts of Be. For this phase of the experiment, artificial saliva (AS), AS with 1% albumin, AS with 1% of mucin and parotid human saliva were employed as electrolytes. The results obtained in the various electrolytes depended on the composition, microstructure, stability of passive film, and the presence of casting porosity of the alloys tested. Proteins had insignificant effect on alloys with highly stable passive films, whereas, corrosion rates increased substantially in those alloys with compromised passive film formation. Proteins, especially mucin, lowered the activity of pores and seemed to produce an inhibitive action against localized corrosion. The same trends were observed in human saliva. To clarify the mechanisms of protein-surface interaction, electrochemical impedance spectroscopy (EIS) was employed with the same alloy-electrolyte combinations. Based on the results, it was hypothesized that proteins are adsorbed to the anodic areas where pits may be forming or casting porosity exists. The electrostatic interaction and affinity of proteins for metallic ions plays a significant role. The absorbed macromolecules physically block transport of reactants to and from the interface and slow down the corrosion reaction appreciably. Overall, this investigation contributed to the further understanding of the electrochemistry of the oral environment, particularly the contribution of proteinaceous species.

Ledvina, Martin

299

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

300

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

Science.gov (United States)

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.

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

2015-02-01

301

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

Directory of Open Access Journals (Sweden)

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.

V. Lazi?

2010-12-01

302

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2013-01-15

303

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.

304

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2014-09-15

305

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

Science.gov (United States)

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.

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

306

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

International Nuclear Information System (INIS)

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

307

Impact of seed layer on material quality of epitaxial germanium on silicon deposited by low pressure chemical vapor deposition  

International Nuclear Information System (INIS)

The impact of the growth conditions of the germanium seed layer on the material quality of epitaxial germanium grown on (100) silicon by Low Pressure Chemical Vapor Deposition is studied. In order to obtain a smooth surface morphology, a thin Ge seed layer is grown at low temperature, followed by a thick Ge cap layer at high temperature. An optimal seed deposition condition of 335 deg. C and 4 kPa is identified. Seed layer growth at lower temperatures (e.g. 320 deg. C) leads to the formation of crystallographic defects, while growth above 350 deg. C produces unacceptable surface roughening associated with rapid Ge surface diffusion. Seed growth pressures above 6 kPa are found to lead to gas phase nucleation. A qualitative growth model for the Ge seed layer at 335 deg. C and 4 kPa is also described. It is demonstrated that a Ge seed layer thickness greater than 30 nm is required to obtain smooth Ge films. For seed layers at or below 30 nm thicknesses, the lowered thermal stability of this thin film produces severe islanding during the transition to the cap growth temperature (650 deg. C). In situ doping with boron above ?1019 cm-3 in the seed layer enhances the seed growth rate and lowers the Ge/Si interfacial oxygen level. For in situ annealed 2 ?m-thick Ge films deposited on this seed layer, a threading dislocation density of ?2 x 107 cm-2 is achieved, along with a surface roughness of ?1.6 nm of ?1.6 nm

308

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

Energy Technology Data Exchange (ETDEWEB)

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.

El-Ella, H W A R; Sadler, T C; Kappers, M J; Oliver, R A, E-mail: he234@cam.ac.u [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke St., Cambridge, CB2 3QZ (United Kingdom)

2010-02-01

309

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.

310

Intercalation and photophysical characterization of 1-pyrenemethylamine in zirconium phosphate layered materials.  

Science.gov (United States)

The ion exchange of the luminescent probe 1-pyrenemethylamine (PYMA) into zirconium phosphate (ZrP) layered materials has been accomplished. The matrices used were the hexahydrated 10.3 A phase of ZrP (10.3 A ZrP, where 10.3 A represents the interlayer distance) and butylammonium-exchanged ZrP (BAZrP) with an expanded 18.6 A interlayer distance. The XRPD patterns for the 10.3 A ZrP after PYMA exchange (PYMA-exchanged ZrP), at high PYMA concentrations, show an increase in the interlayer distance from 10.3 A in unexchanged 10.3 A ZrP to 23.5 A in PYMA-exchanged ZrP, indicating PYMA intercalation. The luminescence spectrum for the PYMA-exchanged ZrP exhibits an excimer band at 458 nm that is absent in the luminescence spectrum of PYMA in aqueous solution at low concentrations. The intensity of the excimer emission increased at low PYMA concentrations. These results are in contrast to experiments using the BAZrP matrix. The XRPD patterns for PYMA-exchanged BAZrP do not show changes in the interlayer distance, which suggests that PYMA is not being intercalated and is only surface bound. The luminescence spectrum for PYMA-exchanged BAZrP exhibits a lower emission intensity in its excimer band, at different PYMA concentrations, compared with the PYMA-exchanged ZrP excimer band. For PYMA-exchanged ZrP, we propose a process in which exchange at low PYMA concentrations occurs at external surface sites with clustering promoting excimer formation followed by exchange at high PYMA concentrations occurring at interior sites reducing excimer formation. PMID:15667164

Bermúdez, Ricardo A; Colón, Yaitza; Tejada, Genaro A; Colón, Jorge L

2005-02-01

311

Wafer-scale process and materials optimization in cross-flow atomic layer deposition  

Science.gov (United States)

The exceptional thickness control (atomic scale) and conformality (uniformity over nanoscale 3D features) of atomic layer deposition (ALD) has made it the process of choice for numerous applications from microelectronics to nanotechnology, and for a wide variety of ALD processes and resulting materials. While its benefits derive from self-terminated chemisorbed reactions of alternatively supplied gas precursors, identifying a suitable process window in which ALD's benefits are realized can be a challenge, even in favorable cases. In this work, a strategy exploiting in-situ gas phase sensing in conjunction with ex-situ measurements of the film properties at the wafer scale is employed to explore and optimize the prototypical Al2O3 ALD process. Downstream mass-spectrometry is first used to rapidly identify across the [H2O x Al(CH3)3] process space the exposure conditions leading to surface saturation. The impact of precursor doses outside as well as inside the parameter space outlined by mass-spectrometry is then investigated by characterizing film properties across 100 mm wafer using spectroscopic ellipsometry, CV and IV electrical characterization, XPS and SIMS. Under ideal dose conditions, excellent thickness uniformity was achieved (1sigma/meansurface. Since adsorbed species are reactive with respect to subsequent dose of the complementary precursor, such depletion magnifies non-uniformities as seen in the cross-flow reactor, thereby decorating deviations from a suitable ALD process recipe. Degradation of the permittivity and leakage current density across the wafer was observed though the film composition remained unchanged. Upon higher water dose in the over-exposure regime, deposition rates increased by up to 40% while the uniformity degraded. In contrast, overdosing of TMA and ozone (used for comparison to water) did not affect the process performances. These results point to complex saturation dynamics of water dependent on partial pressure and potential multilayer adsorption caused by hydrogen-bonding.

Lecordier, Laurent Christophe

312

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

OpenAIRE

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...

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

2013-01-01

313

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

Science.gov (United States)

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

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

2013-01-01

314

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

Science.gov (United States)

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.

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

2014-06-01

315

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

Directory of Open Access Journals (Sweden)

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

Mr.M Basavaraju

2013-09-01

316

Surface characterization of artificial corrosion layers on copper alloy reference materials  

Science.gov (United States)

This paper describes the surface characterization of artificial patina layers on five different copper alloys. The chemical composition of the examined bronzes covers the major families of archaeological copper alloys from antiquity until the Roman period. The patina layers of the five samples were formed under identical conditions by electrochemical means. Light microscopy, scanning electron microscopy with energy dispersive X-ray micro analysis (SEM-EDX) and Fourier transform infrared spectroscopy (FTIR) were used to describe the main properties of the patina layers. The results were interpreted and classified according to an existing corrosion model for copper alloys.

Constantinides, I.; Adriaens, A.; Adams, F.

2002-04-01

317

Highly interconnected porous electrodes for dye-sensitized solar cells using viruses as a sacrificial template  

Energy Technology Data Exchange (ETDEWEB)

A novel means of generating highly interconnected and nano-channeled photoelectrodes by employing one-dimensionally shaped M13 viruses as a sacrificial template is proposed for highly efficient dye-sensitized solar cells (DSSCs). The electrostatic binding between oppositely charged TiO{sub 2} nanoparticles and M13 viruses provides a uniform complexation and suppresses random aggregation of TiO{sub 2} nanoparticles. After the calcination process, the traces of viruses leave porously interconnected channel structures inside TiO{sub 2} nanoparticles, providing efficient paths for electrolyte contact as well as increased surface sites for dye adsorption. As a result, DSSCs generated using a sacrificial virus template exhibit an enhanced current density (J{sub SC}) of 12.35 mA cm-{sup 2} and a high photoconversion efficiency ({eta}) of 6.32%, greater than those of conventional photoelectrodes made of TiO{sub 2} nanoparticles (J{sub SC} of 8.91 mA cm-{sup 2} and {eta} of 4.67%). In addition, the stiffness and shape of the M13 virus can be varied, emphasizing the usefulness of the one-dimensional structural characteristics of M13 viruses for the highly interconnected porous structure of DSSC photoelectrodes. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Lee, Yong Man; Kim, Young Hun; Lee, Jun Haeng; Park, Jong Hyeok; Park, Nam-Gyu; Choe, Woo-Seok; Yoo, Pil J. [School of Chemical Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Ko, Min Jae [Solar Cell Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of)

2011-03-22

318

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.

319

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

Directory of Open Access Journals (Sweden)

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.

Michael D. Blanton

2012-09-01

320

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

Science.gov (United States)

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

Ho, Chia-Chun; Wang, Pei-Hao

2015-03-01

321

Nanocomposite Material Based on GaSe and InSe Layered Crystals Intercalated by RbNO3 Ferroelectric  

Directory of Open Access Journals (Sweden)

Full Text Available In the present study, we established for the first time that single-crystal samples of gallium GaSe and indium InSe selenides can be intercalated by molecules of RbNO3 ferroelectric salt rubidium nitrate. We investigated kinetics of the intercalation process at different temperature-time regimes. Structural properties of the intercalate nanocomposites were studied by X-ray diffraction. The studied structures can be presented as composite superlattices which consist of a lattice of anisotropic layered semiconductor with embedded ferroelectric layers. We established that GaSe nanocomposite material exhibits electric energy storage properties. Energy storage properties are associated with polarization of the intercalated ferroelectric under external electric field. We developed a solid state electric energy storage device on the basis of GaSe nanocomposite material.

Z.R. Kudrynskyi

2013-10-01

322

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

323

Thin-layer chromatography of radioactively labelled cholesterol and precursors from biological material  

International Nuclear Information System (INIS)

The investigation methods of the action of xenobiotics on sterol biosynthesis from 14C-acetate in rat hepatocyte cultures can be developed, with regard to extraction using Extrelut and the separation of the sterol pattern by thin-layer chromatography, in such a way that they are suitable for wider application, e.g., screening. Good visualisation and recognition of changes in the sterol pattern are possible using autoradiography of the thin-layer chromatogram. (orig.)

324

Atomic emission spectroscopic investigations for determining depth profiles at boride layers on iron materials  

International Nuclear Information System (INIS)

A combination of atomic emission spectroscopic surface analysis and mechanical removement of defined surface areas in layers by grinding yields information about the depth distribution of boron in iron. In addition, the evaluation with the aid of the two-dimensional variance analysis leads to statements on the homogeneous distribution within individual layers at different depth. The results obtained in this way are in agreement with those of other methods

325

MODELLING OF ACOUSTIC EMISSION SOURCE AND WAVE RESPONSE IN LAYERED MATERIALS  

Directory of Open Access Journals (Sweden)

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.

Alamin A.

2014-03-01

326

Magnetic materials. Tilt engineering of spontaneous polarization and magnetization above 300 K in a bulk layered perovskite.  

Science.gov (United States)

Crystalline materials that combine electrical polarization and magnetization could be advantageous in applications such as information storage, but these properties are usually considered to have incompatible chemical bonding and electronic requirements. Recent theoretical work on perovskite materials suggested a route for combining both properties. We used crystal chemistry to engineer specific atomic displacements in a layered perovskite, (Ca(y)Sr(1- y))(1.15)Tb(1.85)Fe2O7, that change its symmetry and simultaneously generate electrical polarization and magnetization above room temperature. The two resulting properties are magnetoelectrically coupled as they arise from the same displacements. PMID:25613888

Pitcher, Michael J; Mandal, Pranab; Dyer, Matthew S; Alaria, Jonathan; Borisov, Pavel; Niu, Hongjun; Claridge, John B; Rosseinsky, Matthew J

2015-01-23

327

Some regularities of structure and surface layer properties changing of metal materials after electro-erosion machining  

International Nuclear Information System (INIS)

Effect of electoerosion machining on the surface state of pearlitic class steel of the 12KhN4MFA type, bronzes BrAMts 9-2 and BrAZhNMts 9-4-4-1, of the alloy PT-3V has been studied. As a result of electroerosion machining (EEM) a transformed layer, presenting overheated and partially melted metal, the structure and hardness of which depend on chemical composition of the materials treated, their tendency to phase transformatins and saturation with introduction elements, is formed on the surface of metal materials

328

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

International Nuclear Information System (INIS)

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

329

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

Directory of Open Access Journals (Sweden)

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.

Jia Yao,

2011-12-01

330

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)

331

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

OpenAIRE

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 ...

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

2012-01-01

332

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

Energy Technology Data Exchange (ETDEWEB)

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

Vascon, Alessio

2013-06-26

333

Novel Growing Integration Layer (GIL) method for joining/bonding of metallic and ceramic materials, and its applications for bulk metallic glasses with high bioactivities  

International Nuclear Information System (INIS)

This article describes a new approach to overcome the cracking and peeling of ceramic layer on bulk metallic materials. Based on previous studies and our results, we have proposed a novel concept and technology: Growing Integration Layer (GIL) or Growing Integration Processing (GIP) for the coating, joining and/or bonding of ceramic layer on metallic materials. As one of its application, titanate layers with nano-mesh morphology, having widely diffused interfaces from the Ti-based bulk metallic glass (BMG) have been fabricated by the hydrothermal-electrochemical reaction in an aqueous solutions at low temperatures below 120 oC. This titanate layer could induce the deposition of bone-like hydroxyapatite after 12 days of immersion in a simulated body fluid (SBF). The GIL method exhibited not only the improvement of adhesion performance of ceramic layers but also the introduction of new functionality such as bioactivity to the metallic bulk materials.

334

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

335

Diffusivity measurements of silicon in silicon dioxide layers using isotopically pure material  

Energy Technology Data Exchange (ETDEWEB)

We report measurement of the silicon diffusion coefficient in silicon dioxide films using isotopically enriched {sup 28}Si silicon dioxide layers that enable relatively low {sup 30}Si concentration measurements to be performed using secondary ion mass spectrometry. Two types of experiments are made. {sup 30}Si atoms are introduced in excess in a stoichiometric isotopically pure silicon dioxide layer either by ion implantation or by a predeposition technique. These experiments are representative of any physical situation in which excess silicon atoms are introduced into silicon dioxide layers during silicon processing. The estimated diffusivity values are significantly higher than previously reported values for Si diffusion within a stoichiometric oxide and closer to reported values for excess Si diffusion within an oxide. The activation energy of the diffusivity is found to be 4.74 eV. {copyright} 2001 American Institute of Physics.

Tsoukalas, D.; Tsamis, C.; Normand, P.

2001-06-15

336

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

Science.gov (United States)

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.

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

2014-09-01

337

Influence of the type of ceramic moulding materials on the top layer of titanium precision castings  

Directory of Open Access Journals (Sweden)

Full Text Available The article presents the results of the research which was executed to describe the conditions specific of the formation of surface of certain micro-geometry and of the upper layers on precision titanium castings for medical industry. On the ready precision castings some tests were carried out to obtain the surface micro-geometry satisfying the requirements of implants to be used in human organism. The surfaces with specific spherical macro-unevenness were formed as well as plane surfaces of 2 ÷ 6 ?m roughness. With the help of the light and electron microscopy, the possibility of formation of upper layers directly through an interaction of liquid titanium or Ti6Al4V alloy with the first layer of ceramic mould made from the ceramic mixtures based on Ekosil binder and molochite or zirconia has been confirmed.

Myszka D.

2007-01-01

338

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.

339

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

International Nuclear Information System (INIS)

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

340

An ultra-wideband wire spiral antenna for in-body communications using different material matching layers.  

Science.gov (United States)

In this work an ultra-wideband wire antenna was designed and fabricated for transmitting/receiving signals to/from inside the human body. The antenna provides high gain and thus high field intensity in its broadside direction; hence, a high energy density wireless can be established with the inner body. The proposed antenna operates in the frequency band of 3-10 GHz with an impedance of 200 Ohms in free space. The antenna was embedded in different materials with permittivity values ranging from 12 to 74 in order to evaluate the matching layer effect on wave propagation from outside to inside the body. The antenna port impedance was adjusted by using matching circuits. The electric field intensity inside the human chest was calculated for different materials and depths. The best improvement in wave penetration was obtained for the frequency band of 750-1000 MHz by embedding the antenna inside a material with permittivity equal to 27. PMID:25571603

Khaleghi, Ali; Balasingham, Ilangko; Chavez-Santiago, Raul

2014-01-01

341

Contact-angle measurements as a means of probing the surface alignment characteristics of liquid crystal materials on photoalignment layers  

Science.gov (United States)

The exceptionally high 1054-nm laser-damage resistance of photoalignment materials (approaching that of fused silica) has made it possible to fabricate a wide variety of photoaligned liquid crystal (LC) devices for high-peak-power laser applications. Despite these advances, materials selection and photoalignment exposure conditions are still determined using costly and time-consuming "trial-and-error" methods. The contact angle of a fluid droplet on an alignment layer yields important information about LC-surface physicochemical interactions, and as such, it has potential as a rapid and convenient metric for optimizing photoaligned device quality. To this end, we report on efforts to correlate fluid contact angle with surface energy and azimuthal-anchoring energy to aid in the assessment of alignment quality in photoalignment materials systems.

Marshall, K. L.; Didovets, O.; Saulnier, D.

2014-10-01

342

High performance LiMn2O4 cathode materials grown with epitaxial layered nanostructure for Li-ion batteries.  

Science.gov (United States)

Tremendous research works have been done to develop better cathode materials for a large scale battery to be used for electric vehicles (EVs). Spinel LiMn2O4 has been considered as the most promising cathode among the many candidates due to its advantages of high thermal stability, low cost, abundance, and environmental affinity. However, it still suffers from the surface dissolution of manganese in the electrolyte at elevated temperature, especially above 60 °C, which leads to a severe capacity fading. To overcome this barrier, we here report an imaginative material design; a novel heterostructure LiMn2O4 with epitaxially grown layered (R3?m) surface phase. No defect was observed at the interface between the host spinel and layered surface phase, which provides an efficient path for the ionic and electronic mobility. In addition, the layered surface phase protects the host spinel from being directly exposed to the highly active electrolyte at 60 °C. The unique characteristics of the heterostructure LiMn2O4 phase exhibited a discharge capacity of 123 mAh g(-1) and retained 85% of its initial capacity at the elevated temperature (60 °C) after 100 cycles. PMID:24392731

Lee, Min-Joon; Lee, Sanghan; Oh, Pilgun; Kim, Youngsik; Cho, Jaephil

2014-02-12

343

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

Science.gov (United States)

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.

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

1971-01-01

344

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

Science.gov (United States)

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

Açiksöz, Salih Can

2012-03-01

345

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

Directory of Open Access Journals (Sweden)

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.

Mario Orozco Guzmán

2011-06-01

346

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%

347

Development of sacrificial specimen for fatigue damage prediction of structure (2nd report); Kozobutsu no hiro sonsho yochi no tameno giseishikenhen no kaihatsu ( 2 )  

Energy Technology Data Exchange (ETDEWEB)

The study aims at applying the sacrificial specimen developed by the authors of the paper on practical structures, the sacrificial specimens are secured to a smooth specimen and a boxing welded joint, and fatigue tests are performed under varying stress amplitude. The load is cyclic 8 stage block load that has load frequency distribution similar to exponential distribution. Then, a fatigue life prediction of structural element is studied based on monitoring results of the sacrificial specimen. The obtained results are as follows. The sacrificial specimen shows steady fatigue property without occurrence of peeling off or buckling even under varying stress amplitude. A limited accumulated damage value of the sacrificial specimen is obtained under the varying stress amplitude. While arranging the crack growth curve of the varying sacrificial specimen in N/Nf, they show almost the same shape not depending on the life. The prediction method of fatigue life of a structure is described based on monitoring results of the sacrificial specimen. 9 refs., 16 figs., 2 tabs.

Fujimoto, Y.; Huang, F.; Hada, K.; Sato, A.; Hamada, K.; Iwata, M. [Hiroshima Univ. (Japan)

1998-12-31

348

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

Science.gov (United States)

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

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

2010-03-01

349

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

Energy Technology Data Exchange (ETDEWEB)

MoO{sub 3} and organic/MoO{sub 3} hybrid thin films were prepared on a silicon substrate with an LaAlO{sub 3} or a CeO{sub 2} buffer layer. The MoO{sub 3} thin film, which was deposited by chemical vapor deposition, was soaked in an aqueous sodium hydrosulfite solution and aqueous butylammonium (BuNH{sub 3}) solution to prepare (BuNH{sub 3}) {sub x}MoO{sub 3} hybrid thin films. The high b-axis-oriented MoO{sub 3} 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 MoO{sub 3} grains can be deposited on the buffer layer at high temperatures, indicating that the film can work as a gas-sensing element.

Itoh, Toshio [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimo-Shidami, Moriyama-ku, Nagoya 463-8560 (Japan)]. E-mail: itoh-toshio@aist.go.jp; Matsubara, Ichiro [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimo-Shidami, Moriyama-ku, Nagoya 463-8560 (Japan); Shin, Woosuck [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimo-Shidami, Moriyama-ku, Nagoya 463-8560 (Japan); Izu, Noriya [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimo-Shidami, Moriyama-ku, Nagoya 463-8560 (Japan)

2006-12-05

350

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

351

Ormosiles : a new class of materials for sensitive layers in the development of gas sensors  

OpenAIRE

Organically modified silicates (ORMOSILes) can give a new starting point for the preparation or reactive layers. These noncrystalline solids are built up by a network of siloxane bonds (Si-O-Si) with functional organic groups connected by silicon carbon bonds. The properties of ORMOSILes can be tailored by choosing appropriate functional groups and reaction conditions, which will determine structure and microstructure (e.g. porosity). It is shown that the adsoprtion of gases on the surface of...

Hutter, Frank; Haas, Karl-heinz; Schmidt, Helmut K.

1986-01-01

352

Effect of ?-irradiation on commercial polypropylene based mono and multi-layered retortable food packaging materials  

International Nuclear Information System (INIS)

Irradiation processing of food in the prepackaged form may affect chemical and physical properties of the plastic packaging materials. The effect of ?-irradiation doses (2.5-10.0 kGy) on polypropylene (PP)-based retortable food packaging materials, were investigated using Fourier transform infrared (FTIR) spectroscopic analysis, which revealed the changes happening to these materials after irradiation. The mechanical properties decreased with irradiation while oxygen transmission rate (OTR) was not affected significantly. Colour measurement indicated that Nylon 6 containing multilayer films became yellowish after irradiation. Thermal characterization revealed the changes in percentage crystallinity

353

Effect of ?-irradiation on commercial polypropylene based mono and multi-layered retortable food packaging materials  

Science.gov (United States)

Irradiation processing of food in the prepackaged form may affect chemical and physical properties of the plastic packaging materials. The effect of ?-irradiation doses (2.5-10.0 kGy) on polypropylene (PP)-based retortable food packaging materials, were investigated using Fourier transform infrared (FTIR) spectroscopic analysis, which revealed the changes happening to these materials after irradiation. The mechanical properties decreased with irradiation while oxygen transmission rate (OTR) was not affected significantly. Colour measurement indicated that Nylon 6 containing multilayer films became yellowish after irradiation. Thermal characterization revealed the changes in percentage crystallinity.

George, Johnsy; Kumar, R.; Sajeevkumar, V. A.; Sabapathy, S. N.; Vaijapurkar, S. G.; Kumar, D.; Kchawahha, A.; Bawa, A. S.

2007-07-01

354

Sugar-anionic clay composite materials: intercalation of pentoses in layered double hydroxide  

Science.gov (United States)

The intercalation of non-ionized guest pentoses (ribose and 2-deoxyribose) into the Mg-Al and Zn-Al layered double hydroxides (LDHs) was carried out at 298 K by the calcination-rehydration reaction using the Mg-Al and Zn-Al oxide precursors calcined at 773 K. The resulting solid products reconstructed the LDH structure with incorporating pentoses, and the maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 20 times that by the Zn-Al oxide precursor. The ribose/Mg-Al LDH was observed to have the expanded LDH structure with a broad (003) spacing of 0.85 nm. As the thickness of the LDH hydroxide basal layer is 0.48 nm, the interlayer distance of the ribose/Mg-Al LDH is 0.37 nm. This value corresponds to molecular size of ribose in thickness (0.36 nm), supporting that ribose is horizontally oriented in the interlayer space of LDH. The maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 5 times that of 2-deoxyribose. Ribose is substituted only by the hydroxyl group at C-2 position for 2-deoxyribose. Therefore, the number of hydroxyl group of sugar is essentially important for the intercalation of sugar molecule into the LDH, suggesting that the intercalation behavior of sugar for the LDH was greatly influenced by hydrogen bond between hydroxyl group of the intercalated pentose and the LDH hydroxide basal layers.

Aisawa, Sumio; Hirahara, Hidetoshi; Ishiyama, Kayoko; Ogasawara, Wataru; Umetsu, Yoshio; Narita, Eiichi

2003-09-01

355

Acid modified diatomaceous earth--a sorbent material for thin layer chromatography.  

Science.gov (United States)

Natural diatomaceous earth (DE) is modified by flux calcination and refluxing with acid. To characterize natural DE, modified DE's [flux calcinated (FC)DE and FCDE-I] and silica gel 60GF(254) (Si-60GF(254)) are analyzed microscopically, physically, and chemically by various techniques. FCDE-I and Si-60GF(254) are investigated for their usefulness in the stationary phase of thin layer chromatography (TLC) both individually and in composition. Sodium diethyldithiocarbamate (DEDTC) and ammonium pyrrolidinedithiocarbamate (PyDTC) are prepared as Co or Cu (M) complexes [M(DEDTC)(2) and M(PyDTC)(2), respectively]. These complexes and their mixtures are run on thin layers of Si-60GF(254) and FCDE-I individually, and on various FCDE-I and Si-60GF(254) mixtures. Pure toluene and various toluene-cyclohexane mixtures (3:1, 1:1, 1:2, 1:3, v/v) are used as mobile phases for the running the complexes. The best analytical separations of both M(DEDTC)(2) and M(PyDTC)(2) complexes are obtained when using pure toluene and toluene-cyclohexane (3:1, 1:1, v/v) as mobile phases on FCDE-I-Si-60GF(254) (1:3, 1:1, w/w) layers as stationary phases. This study shows that it is possible to qualitatively analyze and to satisfactorily separate a mixture Cu(2+) and Co(2+) cations on cited chromatographic systems. PMID:18402721

Ergül, Soner; Sava?ci, Sahin

2008-04-01

356

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

Science.gov (United States)

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

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

2014-10-01

357

The influence of atmospheric pollution on the development of the superficial layers on building materials of wayside shrines in Krakow  

Energy Technology Data Exchange (ETDEWEB)

Processes of the deterioration which occur on the surfaces of stony building materials of historical monuments in Krakow are related to the pollution of the atmosphere. Mineralogical studies, based mostly on scanning electron microscopy of samples taken from superficial layers from wayside shrines were performed to establish relation between concentration and composition of air pollution and process of deterioration. The shrines were selected because they are relatively numerous within the town area; and sandstones and limestones of local origin were used for their construction. Investigations results of samples from superficial layers from shrine pillars and statues in areas with high concentration of dust and gases in the atmosphere - old centre of the town, areas near Sendzimir Steel Plant and from areas less polluted - Bielany, Tonie, indicate that they do not differ significantly in the composition. Occurrence of gypsum crystals, high content of sulphur, chlorine, and phosphorus in aggregates of amorphous or partly crystalline aluminosilicates, numerous dust particles with high content of Si and Al or rich in carbon (related to the combustion of coal), particles containing Fe, Zn Cu, Ti are the evidence of the atmosphere pollution influence on deterioration. It is difficult to prove a direct correlation between concentration of air pollution and degree of deterioration of building materials. Deterioration is related to local conditions (local topography, density of building and vegetation). The main difficulty in the interpretation of weathering features of superficial layers of building stones from sideway shrines is caused by different frequency and type of conservation. Non professional reparation and conservation can accelerate processes of deterioration of building materials. 12 refs., 14 figs.

Florczyk, R.; Lach, J.; Michalik, M.; Wilczynska-Michalik, W. [Pedagogical University, Krakow (Poland). Inst. of Geography

1998-12-31

358

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

OpenAIRE

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...

Piwnik, J.; Patejuk, A.

2008-01-01

359

Development of silicon glass for etch reverse layer (SiGERL) materials and BARCs for double patterning process  

Science.gov (United States)

Materials and processes for double patterning using 193nm immersion lithography has been developed for the 32/22 nm node device generations. As for double patterning , some patterning methods have already been reported. For instance, there are LELE (Litho Etch Litho Etch) process and LFLE (Litho Freeze Litho Etch) process. LELE process is complicate and low throughput compared to LFLE process. On the other hand, freezing process and freezing material are needed in LFLE process. Then, we examined the process and the material that was able to form a minute pattern without increasing the number of processes as much as possible. The following is examined as a fine hole patterning process. At first, the pillar pattern is obtained by the X-Y double line dipole exposure. Secondly, the reverse material is applied on the pillar pattern and the subsequent process (dry etching or wet etching process) converts the pillar pattern into a hole pattern. We examined the reverse process and materials, including Silicon Glass for Etch Reverse Layer (SiGERL),and organic Bottom-Anti-Reflective coating (BARC) which is adequate for reflectivity control, lithography and the etching process.

Sakaida, Yasushi; Yaguchi, Hiroaki; Sakamoto, Rikimaru; Ho, Bang-Ching

2009-12-01

360

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)

361

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

Science.gov (United States)

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

Sarker, Ashis K; Hong, Jong-Dal

2012-08-28

362

TEM and electron holography analyses of granular and thin layered Cu-Co magnetic materials  

International Nuclear Information System (INIS)

The paper shows the examples of application of transmission electron microscopy (TEM) techniques for characterization of two types of copper-cobalt magnetic nanomaterials: Cu-10 wt% Co granular giant magnetoresistance (GMR) thin ribbons and thin nanocrystalline Co films deposited on Cu substrate. Quantitative TEM microstructural analyses were used for determination of Co particle size distributions in GMR ribbons. It was demonstrated that the relative resistivity depends on the mean diameter of the cobalt nanoparticles. For nanocrystalline thin Co layers, off-axis electron holography was used to investigate their magnetic structure. The mean in-plane component of the magnetic field in cobalt was calculated from the phase gradient.

363

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

Directory of Open Access Journals (Sweden)

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.

2006-01-01

364

Electric Double Layer Capacitance of Graphene-Like Materials Derived from Single-Walled Carbon Nanotubes  

Science.gov (United States)

We tried to unwrap single-walled carbon nanotubes (SWCNTs) by reducing the oxidized SWCNTs. A transmission electron microscope (TEM) observation revealed that the unwrapped SWCNTs were transformed from a pristine nanotube structure to a sheet-like (graphene-like) structure. Electrochemical measurements demonstrated that the electric double layer capacitance (EDLC) of SWCNTs increases significantly due to the unwrapping treatment. For example, the EDLC (199 F/g) of the unwrapped SWCNTs in 1 M H2SO4 electrolyte at a current rate of 50 mA/g is about four times greater than that (51.9 F/g) of pristine SWCNTs.

Inoue, Tsuyoshi; Mori, Syunsuke; Kawasaki, Shinji

2011-01-01

365

Electron Beam Lithography Using Highly Sensitive Negative Type of Plant-Based Resist Material Derived from Biomass on Hardmask Layer  

Science.gov (United States)

We investigated electron beam (EB) lithography using a novel highly sensitive negative type of plant-based resist material derived from biomass on a hardmask layer for trilayer processes. The chemical design concept for using the plant-based resist material with glucose and dextrin derivatives was first demonstrated in the EB lithography. The 1 µm line patterning images with highly efficient crosslinking properties and low film thickness shrinkage were provided under specific process conditions of EB lithography. The results shown reveal that the alpha-linked disaccharide formed by a 1,1-glucoside bond between two glucose units in dextrin derivatives was an important factor in controlling the highly sensitive EB patterning and developer properties.

Takei, Satoshi; Oshima, Akihiro; Sekiguchi, Atsushi; Yanamori, Naomi; Kashiwakura, Miki; Kozawa, Takahiro; Tagawa, Seiichi

2011-10-01

366

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)

367

A nuclear physical method for determining helium in surface layers of materials  

International Nuclear Information System (INIS)

The method of recoil nuclei, which permits to obtain data on integral content, differential distribution, and in crystal structures - on location in lattice of helium impUrity atoms without sample destruction, has been considered. The method is based on impurity nuclei recording, which are knocked off the sample layer analyzed as a result of elastic cocollisions with accelerated ions. When heavy ions are used the method of recoil nuclei permits to determine helium impurities with the concentration above 5x1012 atom/cm2. The thickness of the layer analyzed can reach 1 ?m at the resolution approximately 40 nm. Determination of helium impurity implanted with the energy up to 200 keV is possible. Results of helium determination in the alloy Ti-Al-V made using a cyclotron with the energy of nitrogen accelerated ions 16 MeV are presented. The bunch current in the chamber constituted 0.05 ?A. To record recoil nuclei a silicon surface-barrier detector with the resolution 40 keV is used. A good separation of peaks corresponding to recoil nuclei of hydrogen and helium adsorbed on the surface sample, which are implanted with the energy 30 keV and dose 5X1017 and 1x1016 atom/cm2, is observed. Residual concentration of helium constitutes 2.45x1016 atom/cm2 for the introduced dose 5x1017 atom/cm2

368

Optical interference effect in layered organic materials studied by UV-Vis absorption spectroscopy  

International Nuclear Information System (INIS)

In this report, UV-Vis absorption spectra of CaF2/Alq3, CaF2/C6 and CaF2/C6/Alq3 versus thickness of the organic layers are compared with the calculated spectra from transfer matrix calculation. Contrary to the total difference between the experimental results and the exponential decay calculation, the qualitative and quantitative similarity between the transfer matrix calculation and experimental results indicates that optical intensity in these organic films can be modulated by their thicknesses, and transfer matrix method is demonstrated as a useful tool to calculate the light propagation in thin-layered organic films. Further calculation shows that the optical electric field near the CuPc/C6 interface can be easily modulated by varying the thickness of C6 if the reflection of cathode is taken into account. Our optimization thickness of solar cells with structure of ITO/CuPc/C6/buffer/Al is 15 nm for CuPc and 52 nm for C6 when the buffer is chosen as 6 nm Alq3

369

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 ?

370

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2013-10-15

371

Influence of oxide layers on the cladding material in a liquid lead environment: a comparison between MATRA and TRACE  

International Nuclear Information System (INIS)

The liquid lead-cooled fast reactor (LFR) is one design proposal for further investigations in the frame of the Generation IV project. Due to the high melting point of lead (327 deg. C), the temperature of operation is in the range of 400 to 500 deg. C. This requires a cladding material, which sustains high temperatures over long time periods. The proposed material will be the ferritic-martensitic steel T-91. One drawback of working in a liquid lead environment is the high solubility of metals in it. A protective oxide layer is one option to face the corrosion issue but has the disadvantage of a low thermal conductivity, which increases the cladding temperature. The layout of the fuel assembly (FA) of the LFR is determined to be either an open quadratic array or a hexagonal design with a wrapper. Both designs influence the thermohydraulic of the core since the heat transfer depends on the geometry of the cooling channel. Investigations of the influence of the oxide layer and of the impact of the heat transfer were done for an open quadratic FA. For the assessment of the above mentioned challenges, the subchannel code MATRA and the system code TRACE were extended and applied. Corresponding results are here compared. (authors)

372

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

373

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

International Nuclear Information System (INIS)

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

374

The computer determination of dose-rate distribution of gamma radiation in the layers of various absorbing materials  

International Nuclear Information System (INIS)

An attempt was made to examine the usefulness of the elaborated computer program for calculation of gamma radiation dose rate for technological purposes. The main problem is the determination of radiation dose absorbed in materials of various type, size and kind. To this end the results of computer calculations were compared with those obtained experimentally. For experimental determinations of dose rate the chemical Fricke dosimeter and ionizing chamber were used. Good agreement of the results was obtained for absorbing layers of air, water and aluminium. In case of concrete, on account of the lack of unanimous data concentrating the properties of this material, serious discrepancy was observed. For polymeric low density materials (foamed and granulated polystyrene) of a thickness up to several centimeters the results were close to those calculated for air and water respectively. The present version of the computer program enables one to calculate, with a good accuracy, the radiation dose rate for a given configuration of radiation sources in the irradiated material. Therefore it may be used for technological purposes. (author). 4 refs, 3 figs, 1 tab

375

Single layer garnet materials for 1 ?m diameter bubble ion-implanted contiguous-disk devices  

International Nuclear Information System (INIS)

Single layer garnet films supporting 1 ?m diameter bubble, ion-implanted contiguous-disk devices were grown from a PbO-B2O3 flux using the LPE method. The films have garnet compositions of the form of (YSmGdX)3 (GaFe)5 O12 where X is either Tm, Yb or Lu. Characteristics of the films are presented. A typical worst case propagation margin of approximately 30 Oe was achieved for a drive field > 45 Oe on close packed circuits with a 4.0 ?m x 4.5 ?m cell on (YSmGdTm)3 (GaFe)5 O12 films. (author)

376

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

Directory of Open Access Journals (Sweden)

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.

Mohd Adib Yahya

2015-01-01

377

Nuclear physical method for determining helium in surface layers of materials  

Energy Technology Data Exchange (ETDEWEB)

The method of recoil nuclei, which permits to obtain data on integral content, differential distribution, and in crystal structures - on location in lattice of helium impurity atoms without sample destruction, has been considered. The method is based on impurity nuclei recording, which are knocked off the sample layer analyzed as a result of elastic cocollisions with accelerated ions. When heavy ions are used the method of recoil nuclei permits to determine helium impurities with the concentration above 5x10/sup 12/ atom/cm/sup 2/. The thickness of the layer analyzed can reach 1 ..mu..m at the resolution approximately 40 nm. Determination of helium impurity implanted with the energy up to 200 keV is possible. Results of helium determination in the alloy Ti-Al-V made using a cyclotron with the energy of nitrogen accelerated ions 16 MeV are presented. The bunch current in the chamber constituted 0.05 ..mu..A. To record recoil nuclei a silicon surface-barrier detector with the resolution 40 keV is used. A good separation of peaks corresponding to recoil nuclei of hydrogen and helium adsorbed on the surface sample, which are implanted with the energy 30 keV and dose 5X10/sup 17/ and 1x10/sup 16/ atom/cm/sup 2/, is observed. Residual concentration of helium constitutes 2.45x10/sup 16/ atom/cm/sup 2/ for the introduced dose 5x10/sup 17/ atom/cm/sup 2/.

Chernov, I.P.; Shadrin, V.N.; Cherdantsev, Yu.P.; Sulema, V.N. (Tomskij Politekhnicheskij Inst. (USSR). Inst. Yadernoj Fiziki, Ehlektroniki i Avtomatiki)

1984-03-01

378

Quantitative evaluation of ultrasonic C-scan image in acoustically homogeneous and layered anisotropic materials using three dimensional ray tracing method.  

Science.gov (United States)

Quantitative evaluation of ultrasonic C-scan images in homogeneous and layered anisotropic austenitic materials is of general importance for understanding the influence of anisotropy on wave fields during ultrasonic non-destructive testing and evaluation of these materials. In this contribution, a three dimensional ray tracing method is presented for evaluating ultrasonic C-scan images quantitatively in general homogeneous and layered anisotropic austenitic materials. The directivity of the ultrasonic ray source in general homogeneous columnar grained anisotropic austenitic steel material (including layback orientation) is obtained in three dimensions based on Lamb's reciprocity theorem. As a prerequisite for ray tracing model, the problem of ultrasonic ray energy reflection and transmission coefficients at an interface between (a) isotropic base material and anisotropic austenitic weld material (including layback orientation), (b) two adjacent anisotropic weld metals and (c) anisotropic weld metal and isotropic base material is solved in three dimensions. The influence of columnar grain orientation and layback orientation on ultrasonic C-scan image is quantitatively analyzed in the context of ultrasonic testing of homogeneous and layered austenitic steel materials. The presented quantitative results provide valuable information during ultrasonic characterization of homogeneous and layered anisotropic austenitic steel materials. PMID:24008174

Kolkoori, Sanjeevareddy; Hoehne, Christian; Prager, Jens; Rethmeier, Michael; Kreutzbruck, Marc

2014-02-01

379

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)

380

Dimensional crossover of thermal transport in few-layer graphene materials  

OpenAIRE

Graphene, in addition to its unique electronic and optical properties, revealed unusually high thermal conductivity. The fact that thermal conductivity of large enough graphene sheets should be higher than that of basal planes of bulk graphite was predicted theoretically by Klemens. However, the exact mechanisms behind drastic alteration of material's intrinsic ability to conduct heat as its dimensionality changes from 2-D to 3-D remain elusive. Recent availability of high-q...

Ghosh, Suchismita; Bao, Wenzhong; Nika, Denis L.; Subrina, Samia; Pokatilov, Evghenii P.; Lau, Chun Ning; Balandin, Alexander A.

2010-01-01

381

Synthesis of Ag-Mn3O4 core-shell nanorods and Mn3O4 nanotubes from sacrificial Ag nanorod templates.  

Science.gov (United States)

Our research focuses on the preparation of Ag-Mn3O4 core-shell nanorods and Mn3O4 nanotubes which have various engineering applications. Hausmannite manganese oxide (Mn3O4) nanotubes were synthesized via a galvanic replacement reaction at mild reaction conditions. The Mn3O4 nanotubes were prepared by solidification of manganese ions on a sacrificial silver nanorod due to the standard reduction potential difference between solid silver and manganese ions. The Mn ions were reduced to solid while the solid Ag rod was oxidized to ions. Ag-Mn3O4 core-shell nanorods and Mn3O4 nanotubes were simply prepared by changing the amount of manganese ions. The Mn3O4 layer in the nanorods and nanotubes had a Hausmannite crystalline structure and showed weak hysteresis of magnetism. This weak magnetism is likely due to the diamagnetic property of silver and multiple magnetic domain of Mn3O4. This simple replacement reaction could be applied to various oxide nanotube fabrications with exact shape control. PMID:19908557

Dong, Hyunbae; Koh, Eoi Kwan; Lee, Sang-Yup

2009-11-01

382

Morphology change of galvanically displaced one-dimensional tellurium nanostructures via controlling the microstructure of sacrificial Ni thin films  

International Nuclear Information System (INIS)

One-dimensional Tellurium (Te) nanostructures with controlled dimensions and morphologies have been synthesized by the galvanic displacement reaction (GDR) of electrodeposited nickel (Ni) thin films. The effects of sacrificial Ni microstructure and HTeO2+ ion concentration on the resulting Te nanostructures were systematically investigated. The preferred crystal orientation of sacrificial Ni thin films was varied to synthesize Te nanostructures with various levels of distinctiveness. By adjusting the concentration of HTeO2+ ions in the galvanic displacement electrolyte, well-aligned one-dimensional (1-D) Te nanostructures such as conical and hexagonal pillars were prepared where the diameter ranged from ?70 to ?900 nm and the length ranged from 1 to 3.6 ?m

383

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)

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.

Jiang, Jin-Wu; Park, Harold S.

2015-03-01

384

Influence of cathode material and SiCl4 gas on inductively coupled plasma etching of AlGaN layers with Cl2/Ar plasma  

International Nuclear Information System (INIS)

The influence of cathode coverplate material on inductively coupled plasma etching of GaN and AlGaN with 1% and 10% of Al was investigated. It was revealed that coverplate material has a great impact on the etching of Al-containing layers. Results obtained with a graphite coverplate and a Si wafer on top of a quartz coverplate indicate that etch products of coverplate material such as SiClx, CClx reactive species and SiClx+, CClx+ ions play a significant role in fast and smooth etching of Al-containing layers. They act as getters to remove oxygen in the process chamber and as effective etchers for oxide layers formed by background oxygen in the process chamber. Experiments where SiCl4 gas was added to Cl2/Ar plasma confirmed the role of SiClx reactive species and SiClx+ ions for fast and smooth etching of AlGaN layers

385

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

Science.gov (United States)

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.

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

2014-12-01

386

a Portable Microwave Interference Scanning System for Nondestructive Testing of Multi-Layered Dielectric Materials  

Science.gov (United States)

A portable, microwave interference scanning system, that can be used in situ, with one-sided, non-contact access, has been developed. It has demonstrated capability of damage detection on composite ceramic armor. Specimens used for validation included specially fabricated surrogates, and non-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 will present details of the system and discuss results obtained.

Schmidt, K. F.; Little, J. R.; Ellingson, W. A.; Green, W.

2009-03-01

387

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

International Nuclear Information System (INIS)

A portable, microwave interference scanning system, that can be used in situ, with one-sided, non-contact access, has been developed. It has demonstrated capability of damage detection on composite ceramic armor. Specimens used for validation included specially fabricated surrogates, and non-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 will present details of the system and discuss results obtained.

388

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

CERN Document Server

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

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

2002-01-01

389

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)

390

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

391

High-performance hierarchical LiNi1/3Mn1/3Co1/3O2 microspheres synthesized via a facile template-sacrificial route  

International Nuclear Information System (INIS)

Highlights: • Microsphere hierarchical LiNi1/3Mn1/3Co1/3O2 was fabricated. • A facile in situ route with MnO2 as the sacrificial template was developed. • Conventional co-precipitate synthesis method was compared. • The hierarchical microsphere sample exhibits superior electrochemical performance. -- Abstract: LiNi1/3Mn1/3Co1/3O2 microspheres have been successfully synthesized via a facile in situ route with MnO2 as the sacrificial template. The as-obtained sample shows a unique nano/micro-hierarchical structure. As a cathode material for lithium-ion battery, the sample exhibits excellent electrochemical performance with higher capacity, superior cycling stability and rate capability as compared with that prepared by conventional co-precipitate reaction method. The discharge specific capacities for the first cycle are 196, 187, 182 and 176 mA h g?1 at 0.1, 0.2, 0.5 and 1 C, respectively. The superior performance can be ascribed to the unique microstructure with numerous nanosized primary particles that can provide rapid pathway for Li+ and e? diffusion, and facilitate the penetration of the electrolyte

392

Raman enhancement effect on two-dimensional layered materials: graphene, h-BN and MoS2.  

Science.gov (United States)

Realizing Raman enhancement on a flat surface has become increasingly attractive after the discovery of graphene-enhanced Raman scattering (GERS). Two-dimensional (2D) layered materials, exhibiting a flat surface without dangling bonds, were thought to be strong candidates for both fundamental studies of this Raman enhancement effect and its extension to meet practical applications requirements. Here, we study the Raman enhancement effect on graphene, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS2), by using the copper phthalocyanine (CuPc) molecule as a probe. This molecule can sit on these layered materials in a face-on configuration. However, it is found that the Raman enhancement effect, which is observable on graphene, hBN, and MoS2, has different enhancement factors for the different vibrational modes of CuPc, depending strongly on the surfaces. Higher-frequency phonon modes of CuPc (such as those at 1342, 1452, 1531 cm(-1)) are enhanced more strongly on graphene than that on h-BN, while the lower frequency phonon modes of CuPc (such as those at 682, 749, 1142, 1185 cm(-1)) are enhanced more strongly on h-BN than that on graphene. MoS2 demonstrated the weakest Raman enhancement effect as a substrate among these three 2D materials. These differences are attributed to the different enhancement mechanisms related to the different electronic properties and chemical bonds exhibited by the three substrates: (1) graphene is zero-gap semiconductor and has a nonpolar C-C bond, which induces charge transfer (2) h-BN is insulating and has a strong B-N bond, while (3) MoS2 is semiconducting with the sulfur atoms on the surface and has a polar covalent bond (Mo-S) with the polarity in the vertical direction to the surface. Therefore, the different Raman enhancement mechanisms differ for each material: (1) charge transfer may occur for graphene; (2) strong dipole-dipole coupling may occur for h-BN, and (3) both charge transfer and dipole-dipole coupling may occur, although weaker in magnitude, for MoS2. Consequently, this work studied the origin of the Raman enhancement (specifically, chemical enhancement) and identifies h-BN and MoS2 as two different types of 2D materials with potential for use as Raman enhancement substrates. PMID:24780008

Ling, Xi; Fang, Wenjing; Lee, Yi-Hsien; Araujo, Paulo T; Zhang, Xu; Rodriguez-Nieva, Joaquin F; Lin, Yuxuan; Zhang, Jin; Kong, Jing; Dresselhaus, Mildred S

2014-06-11

393

Layer by layer evaluation of a PCC pavement as it was constructed: Comparison of backcalculated values to lab material values. Research investigation (final)  

Energy Technology Data Exchange (ETDEWEB)

This study was conducted to observe the background layer strengths of a pavement structure as each layer was constructed and compare these layer strengths to laboratory tested sample strengths. The objective was carried out by gathering Falling Weight Deflectometer deflection data on each sequential layer. The laboratory samples included bulk samples of the base, shelby tube samples of the subgrade, and concrete core samples from the pavement`s structure. Laboratory tests were performed on these extracted samples to estimate the resilient modulus testing on the base samples was not performed because the backcalculated base results were inconclusive and no comparison could be made.

Netemeyer, R.; Munsell, S.

1999-02-01

394

Development of a helium-cooled divertor: Material choice and technological studies  

Science.gov (United States)

Within the framework of the EU power plant conceptual study (PPCS), a He-cooled divertor concept has been investigated at Forschungszentrum Karlsruhe in cooperation with the Efremov Institute. The design goal is to remove a high heat load of at least 10 MW/m 2. The design is based on a modular construction of cooling finger unit that helps reduce thermal stresses. The divertor finger unit, which is cooled by high pressure helium, consists of a tungsten tile as thermal shield and sacrificial layer, and a thimble made of tungsten alloy. The success of this design depends strongly on the effectiveness of the cooling technology and on the availability of appropriate structural materials such as tungsten alloy and oxide-dispersion-strengthened (ODS) steel as well as the related fabrication and joining technology. Results of this investigation are discussed in the paper.

Norajitra, P.; Boccaccini, L. V.; Gervash, A.; Giniyatulin, R.; Holstein, N.; Ihli, T.; Janeschitz, G.; Krauss, W.; Kruessmann, R.; Kuznetsov, V.; Makhankov, A.; Mazul, I.; Moeslang, A.; Ovchinnikov, I.; Rieth, M.; Zeep, B.

2007-08-01

395

Development of a helium-cooled divertor: Material choice and technological studies  

International Nuclear Information System (INIS)

Within the framework of the EU power plant conceptual study (PPCS), a He-cooled divertor concept has been investigated at Forschungszentrum Karlsruhe in cooperation with the Efremov Institute. The design goal is to remove a high heat load of at least 10 MW/m2. The design is based on a modular construction of cooling finger unit that helps reduce thermal stresses. The divertor finger unit, which is cooled by high pressure helium, consists of a tungsten tile as thermal shield and sacrificial layer, and a thimble made of tungsten alloy. The success of this design depends strongly on the effectiveness of the cooling technology and on the availability of appropriate structural materials such as tungsten alloy and oxide-dispersion-strengthened (ODS) steel as well as the related fabrication and joining technology. Results of this investigation are discussed in the paper

396

Preparation of mesoporous carbons from amphiphilic carbonaceous material for high-performance electric double-layer capacitors  

Energy Technology Data Exchange (ETDEWEB)

Amphiphilic carbonaceous material (ACM), with nanoscale dispersion in alkaline aqueous solutions, is synthesized from green needle coke. As a special precursor with small particle size, plenty of functional groups and widened d{sub 002} simultaneously, ACM guarantees subsequent ACM-based activated carbons (AACs) with high specific surface area over 3000 m{sup 2} g{sup -1} as well as well-developed mesoporous structure after KOH activation. Such pore properties enable AACs' high performances as electrode materials for electric double-layer capacitors (EDLCs). In particular, surface area up to 3347 m{sup 2} g{sup -1} together with notable mesopore proportion (26.9%) gives sample AAC814 outstanding EDLC behaviors during a series of electrochemical tests including galvanostatic charge/discharge, CV and electrochemical impedance spectroscopy. The electrode gets satisfactory gravimetric and volumetric specific capacitance at the current density of 50 mA g{sup -1}, up to 348 F g{sup -1} and 162 F cm{sup -3}, respectively. Furthermore, for the mesoporosity, there is only a slight capacitance reduction for AAC814 as the current density reaches 1000 mA g{sup -1}, indicating its good rate performance. It is all the ACM's unique characteristics that make AACs a sort of competitive EDLC electrode materials, both in terms of specific capacitance and rate capability. (author)

Wang, Jin; Chen, Mingming; Wang, Chengyang; Wang, Jiuzhou; Zheng, Jiaming [Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

2011-01-01

397

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

International Nuclear Information System (INIS)

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

398

Anion-exchangeable layered materials based on rare-earth phosphors: unique combination of rare-earth host and exchangeable anions.  

Science.gov (United States)

Layered materials, three-dimensional crystals built from stacking two-dimensional components, are attracting intense interest because of their structural anisotropy and the fascinating properties that result. However, the range of such layered materials that can exchange anions is quite small. Continuing efforts have been underway to identify a new class of anion-exchangeable materials. One major goal is the incorporation of rare-earth elements within the host because researchers expect that the marriage of rare-earth skeleton host and the exchangeable species within the interlayer will open up new avenues both for the assembly of layered materials and for the understanding of rare-earth element chemistry. Such lanthanide layered solids have industrial potential. These materials are also of academic importance, serving as an ideal model for studying the cationic size effect on structure stability associated with lanthanide contraction. In this Account, we present the work done by ourselves and others on this novel class of materials. We examine the following four subtopics regarding these layered anionic materials: (1) synthesis strategy and composition diversity, (2) structural features, (3) structure stability with relative humidity, and (4) applications. These materials can be synthesized either by hydrothermal reactions or by homogeneous precipitation, and a variety of anions can be intercalated into the gallery. Although only cations with a suitable size can form the layered structure, the possible range is wide, from early to late lanthanides. We illustrate the effect of lanthanide contraction on properties including morphology, lattice dimensions, and coordination numbers. Because each lanthanide metal ion coordinates water molecules, and the water molecules point directly into the gallery space, this feature plays a critical role in stabilizing the layered structure. In the 9-fold monocapped square antiprism structure, the humidity-triggered transition between high- and low-hydrated phases corresponds to the uptake of H(2)O molecules at the capping site, which provides further evidence of the importance of water coordination. Applications using this unique combination of rare-earth element chemistry and layered materials include ion-exchange, photoluminescence, catalysis, and biomedical devices. Further exploration of the compounds and new methods for functional modification would dramatically enrich the junction of these two fields, leading to a new generation of layered materials with desirable properties. PMID:20560546

Geng, Fengxia; Ma, Renzhi; Sasaki, Takayoshi

2010-09-21

399

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.

400

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

Energy Technology Data Exchange (ETDEWEB)

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 N{sub 2} adsorption (BET method). The electrochemical properties were characterized by means of cycle voltammetry, galvanostatic charging/discharging, and self-discharge.

Halama, Agnieszka [Electrotechnical Institute, Division of Electrotechnology and Materials Science, Wroclaw (Poland); Szubzda, Bronislaw, E-mail: szubzda@iel.wroc.p [Electrotechnical Institute, Division of Electrotechnology and Materials Science, Wroclaw (Poland); Pasciak, Grzegorz [Electrotechnical Institute, Division of Electrotechnology and Materials Science, Wroclaw (Poland)

2010-10-30

401

Synthesis of porous silica hollow spheres using sacrificial template for drug delivery applications  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, we report on the synthesis of SiO2 hollow spheres using carbon nanospheres as the sacrificial template by hydrothermal method. The synthesized substrates are in a spherical morphology and uniform size distribution. The effects of hydrothermal process, concentration and the reaction temperature were optimized during synthesis of carbon nanospheres. Infrared spectroscopy (IR, and scanning electronic microscopy (SEM methods were used for identification of the synthesized products. The synthesized SiO2 nanospheres were used as drug carrier to investigate in vitro release behavior of monoterpenic phenol isomers, carvacrol and thymol, in simulated body fluid (SBF. Ultraviolet-visible spectroscopy (UV-vis method was carried out to determine the amount of the drugs entrapped in the carrier. The results indicated that SiO2 nanospheres have high ability to adsorb the drugs and there is no need for adjusting the pH during the adsorption process. The drug release profile shows a three stages pattern and indicates a delayed release action.

Rasoul Safdari

2014-06-01

402

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.

403

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

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the performance of various cathodic-protection designs using Aluminum alloys to protect prestressed piles. The results obtained with different system designs (bracelete type-Al/Zn/In alloy, thermosprayed aluminum (3-year evaluation and conventional Al/Zn/In anocies in an epoxy-painted steel bracelet (12-year evaluation, indicated that all of these systems may be used as sacrificial anodes for pile protection. However, the thermosprayed aluminum type can not be used in prestressed concrete piles because the very negative potentials ( < -1100 mV vs. Cu/CuSO4 they supply to the reinforcement could lead to hydrogen embrittlement.

Este trabajo presenta la realización de varios diseños de protección catódica utilizando aleaciones de aluminio para la protección de pilotes pretensados. Los resultados obtenidos con diferentes diseños (aleación de Al/Zn/In, tipo brazalete y aluminio termorociado (3 años de evaluación y ánodos convencionales de Al/Zn/In colocados en un brazalete de acero pintado con epoxy (12 años de evaluación, indicaron que todos estos sistemas pueden ser utilizados como ánodos de sacrificio para la protección de los pilotes. Sin embargo, el sistema con aluminio termorociado no puede ser utilizado en pilotes de acero pretensado debido al potencial muy negativo alcanzado por la armadura (<-1100 mV vs Cu/CuSO4, lo cual podría inducir a daños por hidrógeno.

de Rincón, O.

2003-12-01

404

Deoxyguanosine phosphate mediated sacrificial bonds promote synergistic mechanical properties in nacre-mimetic nanocomposites.  

Science.gov (United States)

We show that functionalizing polymer-coated colloidal nanoplatelets with guanosine groups allows synergistic increase of mechanical properties in nacre-mimetic lamellar self-assemblies. Anionic montmorillonite (MTM) was first coated using cationic poly(diallyldimethylammonium chloride) (PDADMAC) to prepare core-shell colloidal platelets, and subsequently the remaining chloride counterions allowed exchange to functional anionic 2'-deoxyguanosine 5'-monophosphate (dGMP) counterions, containing hydrogen bonding donors and acceptors. The compositions were studied using elemental analysis, scanning and transmission electron microscopy, wide-angle X-ray scattering, and tensile testing. The lamellar spacing between the clays increases from 1.85 to 2.14 nm upon addition of the dGMP. Adding dGMP increases the elastic modulus, tensile strength, and strain 33.0%, 40.9%, and 5.6%, respectively, to 13.5 GPa, 67 MPa, and 1.24%, at 50% relative humidity. This leads to an improved toughness seen as a ca. 50% increase of the work-to-failure. This is noteworthy, as previously it has been observed that connecting the core-shell nanoclay platelets covalently or ionically leads to increase of the stiffness but to reduced strain. We suggest that the dynamic supramolecular bonds allow slippage and sacrificial bonds between the self-assembling nanoplatelets, thus promoting toughness, still providing dynamic interactions between the platelets. PMID:23822180

Martikainen, Lahja; Walther, Andreas; Seitsonen, Jani; Berglund, Lars; Ikkala, Olli

2013-08-12

405

Atomic layer deposition of materials in the Cu2ZnSnS4 system for nanostructured photovoltaics  

Science.gov (United States)

One of the largest challenges to the widespread adoption of solar energy is the cost. Cu2ZnSnS4 provides an interesting potential solution as a very cheap absorbing material, because the components are earth-abundant (compared to In, Te) and non-toxic (compared to Cd). This work encompasses efforts to produce Cu2ZnSnS4 via atomic layer deposition, with the intent of laying the groundwork for making an extremely thin absorber photovoltaic device. Depositions of the compounds Cu2S, SnS 2, and ZnS are described, with the resulting thin films showing band gaps and stoichiometry similar to bulk samples. The ideal deposition parameters of ZnS were especially of interest due to the use of a newer, non-pyrophoric zinc precursor, Zn(TMHD)2. Multi-layered films of CuxS (x˜2) and ZnS were studied with extended x-ray absorption fine structure measurements, which determined that the films are dominated by copper, while the zinc is relegated to islands on the surface where it oxidizes. This effect is likely due to the incompatible crystal structures of ZnS and Cu2S, and is diminished in films with thicker layers with the ZnS deposited first. Finally, chemical vapor depositions of Cu2S followed by SnS 2 were annealed at 450°C in H2S to produce Cu2SnS 3, which now only requires the addition of CVD ZnS to make Cu2 ZnSnS4 for a photovoltaic device.

Short, Andrew J.

406

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

International Nuclear Information System (INIS)

Methods are investigated to increase operation properties of zirconium items by modifying their structure-phase state: by liquid metal reinforcement by ordered structures, by methods of solid phase alloying by carbon nanostructures, by methods of granular metallurgy; and also by modifying the surface conditions: using dynamic impact of microbodies and applying of fine surface layers (coatings) by electroarc and magnetron sputtering. The investigations have resulted in obtaining several versions of composite materials based on Russian industrial zirconium alloys having an increased level of properties. The processes have been developed to modify surface and to make protective coatings on the surface of zirconium items. The developed modification methods can be used to increase operation properties and prolong service life of zirconium components of new generation LWR active cores. (author)

407

Material properties of CuGaSe2 absorber films prepared by rapid thermal annealing of stacked elemental layers  

International Nuclear Information System (INIS)

In this study, the reaction kinetics and material properties of polycrystalline CuGaSe2 thin films are reported. The films were prepared by the rapid thermal processing of thermally evaporated glass/Ga/Se/Cu//Ga/Se stacked precursors. In order to gain insight into the chalcopyrite formation process, stacked elemental layers with different Cu/Ga atomic ratios were annealed in an Ar/Se atmosphere under different thermal conditions. For typical annealing temperatures below 600 deg C, x-ray fluorescence studies indicated that a homogeneous element distribution could only be obtained for stoichiometric or near-stoichiometric samples. Systematic studies indicated that temperatures above 600 deg C are required in order to enhance the crystallinity and in-depth compositional uniformity of Ga-rich CuGaSe2 thin films. These results also highlighted the structural limitation of high gallium containing chalcopyrite thin films

408

Mechanically stacked 1 nm thick carbon nanosheets: Ultrathin layered materials with tunable optical, chemical and electrical properties  

CERN Document Server

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...

Nottbohm, Christoph T; Beyer, Andre; Stosch, Rainer; Golzhauser, Armin; 10.1002/smll.201001993

2011-01-01

409

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.

410

Inversion of V(z) data in the Scanning Acoustic Microscope (SAM) to determine material properties of a layered solid  

Science.gov (United States)

A systematic inversion scheme is proposed for the characterization of the material properties of a layered solid from measures V(z) data by Scanning Acoustic Microscope (SAM). The approach is based on the perturbation of V(z) function and two iterative procedures: the well-known damped least-squares (DLS) method and the pseudo- second-derivative (PSD) method. By using these methods, we have successfully obtained the inversion solutions of V(z) inversion problem from the theoretical simulation test and from practical measured V(z) data. Furthermore, the generalized inverse approach is also applied to V(z) problem in order to provide the designer with some useful means for evaluation in the inversion course.

Yu, Zuliang; Boseck, Siegfried

411

Ordered and layered structure of liquid nitromethane within a graphene bilayer: toward stabilization of energetic materials through nanoscale confinement.  

Science.gov (United States)

The structural characteristics involving thermal stabilities of liquid nitromethane (NM)—one of the simplest energetic materials—confined within a graphene (GRA) bilayer were investigated by means of all-atom molecular dynamics simulations and density functional theory calculations. The results show that ordered and layered structures are formed at the confinement of the GRA bilayer induced by the van der Waals attractions of NM with GRA and the dipole-dipole interactions of NM, which is strongly dependent on the confinement size, i.e., the GRA bilayer distance. These unique intermolecular arrangements and preferred orientations of confined NM lead to higher stabilities than bulk NM revealed by bond dissociation energy calculations. PMID:25672840

Liu, Yingzhe; Yu, Tao; Lai, Weipeng; Kang, Ying; Ge, Zhongxue

2015-03-01

412

Penetration of induction-charged particles into an adhesive material layer and their film formation; Yudotai denryushigun no denkyokubanjo seccyakuzaisochu eno shinnyu kyodo to himaku keisei  

Energy Technology Data Exchange (ETDEWEB)

Penetration of induction-charged particles, through a field with horizontally set parallel plate electrodes, into an adhesion layer on the lower surface of an upper electrode and their film formation are investigated by an experimental approach, using polyurethane, alumna, and silica powders. The results of the experiment on powder coated film thickness are explained on the basis of ratio of thickness of adhesive material layer to particle diameter. In a thin film of adhesive material, powder-coated film thickness equa