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1

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

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

Ramadan, Khaled S

2012-04-01

2

Study on the fabrication and releasing of sacrificial layer of micro-cantilever  

Science.gov (United States)

Polyimide is used as sacrificial layer material during the research on bi-material micro-cantilever structure. Contrasted with other sacrificial layer materials, polyimide is marked with excellent properties, like good insulation, big coefficient of elasticity, big coefficient of linear expansion and outstanding mechanical property. This dissertation has studied the preparing process of sacrificial layer, like sacrificial layer imaging and solidifying, and different methods to release sacrificial layer and how to control all kinds of parameters to obtain the best suspension. Finally, the optimized process parameters are obtained.

Liu, Liang; Liu, Weiguo; Liu, Huan

2013-12-01

3

In-situ deposition of sacrificial layers during ion implantation  

Energy Technology Data Exchange (ETDEWEB)

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

Anders, A.; Anders, S.; Brown, I.G.; Yu, K.M.

1995-02-01

4

High dose, heavy ion implantation into metals: the use of sacrificial surface layers to enhance retention  

International Nuclear Information System (INIS)

While of considerable interest for the production of metallic alloys, high dose, heavy ion implantation is highly problematical, since the process is limited by sputtering effects. Sputtering is less significant, however, for light target materials, such as C and Al. This paper summarizes studies involving the use of light materials (such as C and Al) which act as slowly sputtering ''sacrificial layers'' when deposited on metallic targets prior to heavy ion implantation. The use of C and Al sacrificial coatings has enabled implanted ion retentions of 100% to be obtained in a number of ion-metal target systems, where the retentions in uncoated samples were as low as 20%. Ion implantation invariably leads to mixing at the sacrificial layer-metal target interface. This mixing may be detrimental in certain systems, so it is useful to be able to minimize or remove this mixed region. To achieve this, a number of techniques have been investigated: (1) removal of the mixed region in the latter stages of the implant; (2) using a barrier layer or chemical effects to minimize mixing at the sacrificial layer-metal interface; (3) choosing a sacrificial layer material which forms a mixed region which has desirable properties. The results of these investigations, for a number of different ion-target systems, are outlined in this paper. (orig.)

1994-07-01

5

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

6

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

Science.gov (United States)

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

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

2014-03-01

7

Structuration of zero-shrinkage LTCC using mineral sacrificial materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

8

Shadowgraphy investigation of laser-induced forward transfer: Front side and back side ablation of the triazene polymer sacrificial layer  

International Nuclear Information System (INIS)

Thin films of a photodecomposible triazene polymer are used as sacrificial layer for the micro-deposition of sensitive materials by laser-induced forward transfer. To understand the ablation process of this sacrificial layer, the ultraviolet laser ablation of triazene films was investigated by time-resolved shadowgraphy. Irradiation from the film side shows a complete decomposition into gaseous fragments, while ablation through the substrate causes ejection of a solid flyer of polymer. The occurence of the flyer depends on the film thickness as well as on the applied fluence, and a compact flyer is obtaind when these two parameters are optimized

2009-03-01

9

Formation of oxidation induced stacking sacrificial thinning of SIMOX materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sacrificial thermal oxidation of standard SIMOX is currently the main route to form ultra thin film SIMOX structures. During the oxidation process self interstitials are injected into the silicon overlayer and these point defects can lead to the growth of secondary defects, in particular oxidation induced stacking faults (OISF). The formation of these OISF is influenced by the presence of stacking fault tetrahedra (SFT) in the silicon overlayer. In this paper we investigate the formation o...

1993-01-01

10

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.

2010-07-01

11

Methods for making thin layers of crystalline materials  

Energy Technology Data Exchange (ETDEWEB)

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

12

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 sup...

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

2009-01-01

13

Altering the dewetting characteristics of ultrathin gold and silver films using a sacrificial antimony layer.  

Science.gov (United States)

Solid state dewetting of ultrathin films is the most straightforward means of fabricating substrate-supported noble metal nanostructures. This assembly process is, however, quite inflexible, yielding either densely packed smaller structures or widely spaced larger structures. Here, we demonstrate the utility of introducing a sacrificial antimony layer between the substrate and noble metal overlayer. We observe an agglomeration process which is radically altered by the concurrent sublimation of antimony. In stark contrast with conventional dewetting, where the thickness of the deposited metal film determines the characteristic length scales of the assembly process, it is the thickness of the sacrificial antimony layer which dictates both the nanoparticle size and interparticle spacing. The result is a far more flexible self-assembly process where the nanoparticle size and areal density can be varied widely. Demonstrations show nanoparticle areal densities which are varied over four orders of magnitude assembled from the identical gold layer thickness, where the accompanying changes to nanostructure size see a systematic shift in the wavelength of the localized surface plasmon resonance. As a pliable self-assembly process, it offers the opportunity to tailor the properties of an ensemble of nanostructures to meet the needs of specific applications. PMID:23154213

Farzinpour, P; Sundar, A; Gilroy, K D; Eskin, Z E; Hughes, R A; Neretina, S

2012-12-14

14

Altering the dewetting characteristics of ultrathin gold and silver films using a sacrificial antimony layer  

International Nuclear Information System (INIS)

Solid state dewetting of ultrathin films is the most straightforward means of fabricating substrate-supported noble metal nanostructures. This assembly process is, however, quite inflexible, yielding either densely packed smaller structures or widely spaced larger structures. Here, we demonstrate the utility of introducing a sacrificial antimony layer between the substrate and noble metal overlayer. We observe an agglomeration process which is radically altered by the concurrent sublimation of antimony. In stark contrast with conventional dewetting, where the thickness of the deposited metal film determines the characteristic length scales of the assembly process, it is the thickness of the sacrificial antimony layer which dictates both the nanoparticle size and interparticle spacing. The result is a far more flexible self-assembly process where the nanoparticle size and areal density can be varied widely. Demonstrations show nanoparticle areal densities which are varied over four orders of magnitude assembled from the identical gold layer thickness, where the accompanying changes to nanostructure size see a systematic shift in the wavelength of the localized surface plasmon resonance. As a pliable self-assembly process, it offers the opportunity to tailor the properties of an ensemble of nanostructures to meet the needs of specific applications. (paper)

2012-12-14

15

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

16

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2005-01-01

17

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2014-01-01

18

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

International Nuclear Information System (INIS)

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

1982-01-01

19

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

Science.gov (United States)

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.

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

2013-07-01

20

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

 
 
 
 
21

Fabrication of Tunable InP/Air-gap Fabry-Perot Cavities by Selective Etching of InGaAs Sacrificial Layers  

Science.gov (United States)

We report the fabrication of InP/air-gap Fabry-Perot resonant cavities with an improved tunability characteristic achieved through the micromachining of more flexible suspended InP beams. The micromechanical structures are electrostatically actuated. A tuning range of 55nm is demonstrated for an actuation voltage of 12V. The low leakage current, of less than 10?A for a bias of up to 30V, provides a low actuation power. The tunable air-gap cavities are fabricated by selective wet etching of InGaAs sacrificial layers. An FeCl3 based etchant is used to completely remove the InGaAs material without affecting the thickness of the InP layer. The anisotropy of the etch rate of InGaAs was also investigated and exploited in the micromachining process.

Chitica, Nicolae; Daleiden, Jürgen; Bentell, Jonas; André, Janos; Strassner, Martin; Greek, Staffan; Pasquariello, Donato; Karlsson, Mikael; Gupta, Ram; Hjort, Klas

22

Ge and GeOx films as sacrificial layer for MEMS technology based on piezoelectric AlN: etching and planarization processes (Invited Paper)  

Science.gov (United States)

In this article we present a study of deposition and etching techniques of germanium (Ge) and amorphous oxygen germanium (GeOx) films, with the aim of using them as sacrificial layer in the fabrication of AlN-based MEMS by surface micromachining processes. The Ge and GeOx layers were deposited by RF magnetron sputtering in Ar and Ar/O2 atmospheres. By controlling the process parameters we were able to set the final composition of the GeOx films, which was assessed by FTIR measurements. We have studied the etch rates of GeOx films with x ranging from 0 to 1 in H2O2 and H2O2/acid solutions. Depending on the etching temperature and the oxygen content in the layers, etch rates ranging from 0.2 to 2 ?m/min were obtained. Nearly stoichiometric germanium oxide (GeO2) was etched in pure H2O at very high rate (>1 ?m/min at room temperature). We have also developed a chemomechanical polishing (CMP) process for the planarization of Ge and GeOx. The influence of the slurries containing diverse powders (CeO2, Al2O3) and chemical agents (NH4OH, HCl), the different pads, and the various process parameters on the removal rate and the final sample topography has been studied. Finally, we have analysed the compatibility of the materials involved in the process flow with the processes of planarization and removal of the sacrificial layers.

Sangrador, J.; Olivares, J.; Iborra, E.; Vergara, L.; Clement, M.; Sanz-Hervas, A.

2005-07-01

23

Fabrication of Covalently Crosslinked and Amine-Reactive Microcapsules by Reactive Layer-by-Layer Assembly of Azlactone-Containing Polymer Multilayers on Sacrificial Microparticle Templates.  

Science.gov (United States)

We report on the fabrication of covalently crosslinked and amine-reactive hollow microcapsules using 'reactive' layer-by-layer assembly to deposit thin polymer films on sacrificial microparticle templates. Our approach is based on the alternating deposition of layers of a synthetic polyamine and a polymer containing reactive azlactone functionality. Multilayered films composed of branched poly(ethylene imine) (BPEI) and poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) were fabricated layer-by-layer on the surfaces of calcium carbonate and glass microparticle templates. After fabrication, these films contained residual azlactone functionality that was accessible for reaction with amine-containing molecules. Dissolution of the calcium carbonate or glass cores using aqueous ethylenediamine tetraacetic acid (EDTA) or hydrofluoric acid (HF), respectively, led to the formation of hollow polymer microcapsules. These microcapsules were robust enough to encapsulate and retain a model macromolecule (FITC-dextran) and were stable for at least 22 hours in high ionic strength environments, in low and high pH solutions, and in several common organic solvents. Significant differences in the behaviors of capsules fabricated on CaCO(3) and glass cores were observed and characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Whereas capsules fabricated on CaCO(3) templates collapsed upon drying, capsules fabricated on glass templates remained rigid and spherical. Characterization using EDS suggested that this latter behavior results, at least in part, from the presence of insoluble metal fluoride salts that are trapped or precipitate within the walls of capsules after etching of the glass cores using HF. Our results demonstrate that the assembly of BPEI/PVDMA films on sacrificial templates can be used to fabricate reactive microcapsules of potential use in a wide range of fields, including catalysis, drug and gene delivery, imaging, and biomedical research. PMID:21383867

Saurer, Eric M; Flessner, Ryan M; Buck, Maren E; Lynn, David M

2011-02-14

24

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

25

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

International Nuclear Information System (INIS)

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/cm2, 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)

2011-03-01

26

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

Science.gov (United States)

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°C/60 min + 700°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/cm2, 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 900°C for 90 min.

Caizhen, Zhang; Yongshun, Wang; Zaixing, Wang

2011-03-01

27

Solvent bonding of poly(methyl methacrylate) microfluidic chip using phase-changing agar hydrogel as a sacrificial layer.  

Science.gov (United States)

In this report, a solvent bonding method based on phase-changing agar hydrogel has been developed for the fabrication of poly(methyl methacrylate) (PMMA) microfluidic chips. Prior to bonding, the channels and the reservoir ports on PMMA channel plates were filled with molten agar hydrogel that could gelate to form solid sacrificial layers at room temperature. Subsequently, PMMA cover sheets were covered on the channeled plates and 1,2-dichlororethane was applied to the interspaces between them. The agar hydrogel in the channels could prevent the bonding solvent and the softened surface of the PMMA cover sheets from filling in the channels. After solvent bonding, the agar hydrogel in the channels and the reservoir ports was melted and removed under pressure. The sealed channels in the complete microchips had been examined by an optical microscope and a scanning electron microscope. The results indicated that high-quality bonding was achieved at room temperature. The prepared microfluidic microchips have been successfully employed in the electrophoresis separation and detection of three cations in combination with contactless conductivity detection. PMID:22072551

Gan, Zhibin; Zhang, Luyan; Chen, Gang

2011-11-01

28

Fabrication of polymer micro-devices based on organic sacrificial pastes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

29

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

Science.gov (United States)

A fabrication method, based on thin film buckling, is demonstrated to form unique membranes that can be used for applications in optics and biosensing. This method should be applicable to a variety of material systems, which, along with its simplicity and compatibility with different film architectures, allows for widespread implementation. PMID:24096903

Larsen, George K; Zhao, Yiping

2013-11-21

30

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

31

Pt/Ti Electrodes of PZT Thin Films Patterning by Novel Lift-Off Using ZnO as a Sacrificial Layer  

International Nuclear Information System (INIS)

We achieve a successful novel lift-off of patterning Pt/Ti electrodes on SiO2/Si substrates by employing ZnO sacrificial layer deposition and patterning, successive uniform Pt/Ti deposition and final lift-off. Then we deposit PZT thin films on the electrodes. Compared with the conventional lift-off processes for the electrodes, this novel process does not need post-annealing, which must be performed after conventional lift-off process. It is demonstrated that the electrodes patterned by the novel lift-off process have stronger adhesion. The electrodes and the PZT films on the electrodes are more compact and smoother than those by the conventional lift-off process

2008-01-01

32

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

33

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-01-01

34

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 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.

2013-01-01

35

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

36

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

Science.gov (United States)

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 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.

Li, Hui; Li, Gui; Li, Zhiping; Lu, Cuimei; Li, Yanan; Tan, Xianzhou

2013-01-01

37

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

38

Composite sacrificial anodes for offshore structures  

Energy Technology Data Exchange (ETDEWEB)

An updated version of sacrificial anodes for cathodic protection of structures immersed in seawater was recently patented. The anode, constructed in two anodic materials (aluminum alloy on the inside and magnesium alloy on the surface), offers significant reductions in weight and cost. These reductions are due to the highly protective calcareous deposit that forms on the immersed structure when these anodes are used. Characteristics of the deposit and anode performance are reported.

Rossi, S.; Bonora, P.L.; Pasinetti, R.; Benedetti, L. [Univ. of Trento (Italy); Draghetti, M. [AGIP Off Shore, Milan (Italy); Sacco, E. [AGIP DIRA, Ravenna (Italy)

1996-02-01

39

Reductive decontaminaion by using sacrificial electrode  

International Nuclear Information System (INIS)

A high-concentration (5-10 %) agent has generally been used for separate chemical decontamination of individual instruments, such as pumps, installed in a nuclear power plant. Being highly acidic, however, most of the conventional decontamination agents may corrode the instruments under decontamination treatment. The present report addresses the development of a process which permits efficient decontamination in a less corrosive agent with low acidity in the nearly neutral range. The dissolution rate of oxidized iron can be highly increased by reducing the trivalent iron ion into bivalent one. To demonstrate this, an investigation is made to determine the effects of cathode polarization on the dissolution of magnetite, a major component in radioactive oxide film formed on piping wall. A process is developed which uses a sacrificial anode to reduce iron oxides. If a metal used as the sacrificial anode is lower in natural potential and more easily corroded than the material under decontamination treatment, the corrosion of the metal takes place to give electrons to the oxides on the material surface to promote their dissolution. To demonstrate the efficiency of this process, an investigation is made using a neutral decontamination agent together with stainless steel and carbon steel as material for decontamination and sacrificial anode, respectively. (Nogami, K.)

1988-01-01

40

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

Energy Technology Data Exchange (ETDEWEB)

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

Park, Jong Hwa; Kim, Jong Hwan; Min, Byung Tae; Kim, Hwan Yeol; Hong, Seong Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-05-15

 
 
 
 
41

Studies towards freestanding GaN in hydride vapor phase epitaxy by in-situ etching of a sacrificial ZnO buffer layer  

Energy Technology Data Exchange (ETDEWEB)

By in-situ etching of a ZnO buffer layer freestanding GaN layers were prepared by hydride vapor phase epitaxy (HVPE). For the template growth, single crystalline ZnO buffer layers, grown by pulsed laser deposition on sapphire, were used. They were overgrown with a thin GaN layer by a multilayer growth using metal organic vapor phase epitaxy (MOVPE). The removal of the ZnO buffer during the HVPE growth allowed the fabrication of strain-free freestanding GaNlayers with a full width-half-maximum of the donor bound exciton (D{sup 0}X) of 2.3 meV at a position of 3.47 eV in low temperature (15 K) photoluminescence (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Lipskil, Frank; Thapa, Sarad B.; Hertkorn, Joachim; Wunderer, Thomas; Schwaiger, Stephan; Scholz, Ferdinand [Institute of Optoelectronics, Ulm University, 89081 Ulm (Germany); Feneberg, Martin; Wiedenmann, Michael; Thonke, Klaus [Institute of Semiconductor Physics, Ulm University, 89081 Ulm (Germany); Hochmuth, Holger; Lorenz, Michael; Grundmann, Marius [Semiconductor Physics Group, Institute for Experimental Physics II, University Leipzig, 04103 Leipzig (Germany)

2009-06-15

42

LTCC free-standing structures with mineral sacrificial paste  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work, mineral sacrificial pastes (MSP) previously developed for standard thick-film technology (alumina substrates) are extended to LTCC in order to make a capacitive anemometer. Application of MSP materials on free-sintering (unconstrained and not zero-shrinkage) LTCC is challenging: shrinkage must be matched to that of the LTCC in order to avoid excessive deformation, or sufficiently compliant materials must be used. Here, different MSP materials / materials systems are...

Fournier, Yannick; Triverio, Olivier; Maeder, Thomas; Ryser, Peter

2008-01-01

43

Dielectric function of layered materials  

International Nuclear Information System (INIS)

The dielectric response function is calculated for a layered system. The calculation includes electron-electron and electron-phonon interactions. The phonons polarized perpendicular and parallel to the c axis enter the screening function very differently

1990-09-01

44

KAPOOL experiments to simulate molten corium - sacrificial concrete interaction  

Energy Technology Data Exchange (ETDEWEB)

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 {approx} 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)

Eppinger, B.; Fieg, G.; Tromm, W. [Forschungszentrum Karlsruhe, Institute fur Kern-und Energietechnik, Karlsruhe (Germany)

2001-07-01

45

Atomic layer deposition-based synthesis of photoactive TiO2 nanoparticle chains by using carbon nanotubes as sacrificial templates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Highly ordered and self supported anatase TiO2 nanoparticle chains were fabricated by calcining conformally TiO2 coated multi-walled carbon nanotubes (MWCNTs). During annealing, the thin tubular TiO2 coating that was deposited onto the MWCNTs by atomic layer deposition (ALD) was transformed into chains of TiO2 nanoparticles (similar to 12 nm diameter) with an ultrahigh surface area (137 cm(2) per cm(2) of substrate), while at the same time the carbon from the MWCNTs was removed. Photocatalyti...

2014-01-01

46

Method of designing layered sound absorbing materials  

Science.gov (United States)

A widely used model for describing sound propagation in porous materials is the Johnson-Champoux-Allard model. This rigid frame model is based on five geometrical properties of the porous medium: resistivity, porosity, tortuosity, and viscous and thermal characteristic lengths. Using this model and with the knowledge of such properties for different absorbing materials, the design of a multiple layered system can be optimized efficiently and rapidly. The overall impedance of the layered systems can be calculated by the repeated application of single layer impedance equation. The knowledge of the properties of the materials involved in the layered system and their physical meaning, allows to perform by computer a systematic evaluation of potential layer combinations rather than do it experimentally which is time consuming and always not efficient. The final design of layered materials can then be confirmed by suitable measurements. A method of designing the overall acoustic absorption of multiple layered porous materials is presented. Some aspects based on the material properties, for designing a flat layered absorbing system are considered. Good agreement between measured and computed sound absorption coefficients has been obtained for the studied configurations. [Work supported by N.S.E.R.C. Canada, F.C.A.R. Quebec, and Bombardier Aerospace.

Atalla, Youssef; Panneton, Raymond

2002-11-01

47

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

48

Nano transfer and nanoreplication using deterministically grown sacrificial nanotemplates  

Science.gov (United States)

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

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

2012-03-27

49

Materials research, superconductor and thin layer technology  

Science.gov (United States)

Materials research into polymer electric conductors, organic and inorganic polymer microspheres for chromatography, electronic gas sensor corrosion protection of historic glass windows, soldering of ceramics and metals, fiber reinforced automobile parts, superconductors, and thin layer technology is summarized.

1987-11-01

50

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

2010-01-01

51

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 implemented

1994-11-01

52

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).

53

Layered zeolite materials and methods related thereto  

Energy Technology Data Exchange (ETDEWEB)

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

54

Development of corrosion resistant aluminum heat exchanger, Part 1: Development of new aluminum alloy sheets for sacrificial anode  

Energy Technology Data Exchange (ETDEWEB)

The sacrificial anodic effect of Al-Zn alloy reduced markedly in aluminium heat exchanger as car air conditioner manufactured by vacuum brazing conventionally used, as zinc elements preferentially evaporate in vacuum-heating. It was found that Al-Sn alloy had superior electrochemical characteristics than Al-Zn alloy (AA7072) as the sacrificial anodic material used in vacuum brazing. According to many experimental results, the new brazing sheet-fin with Al-Mn-Sn alloy core metal has been developed. This fin has favorable formability and prominent sacrificial anodic effect. Therefore, this fin is excellent material for car air conditioner manufactured by vacuum brazing.

Hagiwara, M.; Baba, Y.; Tanabe, Z.; Miura, T.; Hasegawa, Y.; Iijima, K.

1986-01-01

55

Nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates  

Energy Technology Data Exchange (ETDEWEB)

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. A method includes depositing a catalyst particle on a surface of a substrate to define a deterministically located position; growing an aligned elongated nanostructure on the substrate, an end of the aligned elongated nanostructure coupled to the substrate at the deterministically located position; coating the aligned elongated nanostructure with a conduit material; removing a portion of the conduit material to expose the catalyst particle; removing the catalyst particle; and removing the elongated nanostructure to define a nanoconduit.

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

2011-05-17

56

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

57

Sacrificial plastic mold with electroplatable base  

Energy Technology Data Exchange (ETDEWEB)

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)

2002-01-01

58

Sacrificial Plastic Mold With Electroplatable Base  

Energy Technology Data Exchange (ETDEWEB)

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

59

Reactive two-dimensional layered material with regular chlorine groups.  

Science.gov (United States)

A novel reactive layered two-dimensional molecular space material [layered chloroacetamide phenyl silica (CAAPhS)] with regular chlorine groups was synthesized by grafting chlorine groups into the layer structure of layered aminophenyl silica. The reactive activity of chlorine groups regularly arranged in the layer structure of layered CAAPhS was confirmed through a substitution reaction with n-butylamine. Layered CAAPhS showed potential as a starting material for the formation of a series of two-dimensional layered materials with various regular functional molecules and organic-inorganic composite materials. PMID:17689551

Yao, Ken; Fu, Ying; Shi, Liyi; Wan, Wen; You, Xiaoqing; Yu, Futao

2007-11-01

60

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-10-01

 
 
 
 
61

Computational Discovery, Characterization, and Design of Single-Layer Materials  

Science.gov (United States)

Single-layer materials open up tremendous opportunities for applications in nanoelectronic devices and energy technologies. We first review the four components of a materials science tetrahedron for single-layer materials. We then provide a theoretical perspective of characterizing single-layer materials. This leads to a general data-mining process to predict and computationally characterize emerging single-layer materials. Finally, we comment on limitations and possible improvements of current computational procedures for the discovery, characterization, and design of single-layer materials.

Zhuang, Houlong L.; Hennig, Richard G.

2014-03-01

62

Radionuclide separations using pillared layered materials  

Energy Technology Data Exchange (ETDEWEB)

This is the final report of a two-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Pillared Layered Materials (PLMs) are layered inorganic ion exchangers propped apart by metal oxide pillars. PLMs have been synthesized to sorb strontium from liquid nuclear wastes. A study that compared over 60 sorbers for their ability to sorb strontium from Hanford simulants showed that PLMs were the best sorbers; strontium distribution coefficients ({sup Sr}K{sub d}) > 20000 mL/g were obtained. In addition, PLMs showed a high degree of selectivity for strontium over cesium, transition metals, lanthanides and actinides. The sorption of strontium is, however, inhibited by complexants (EDTA); {sup Sr}K{sub d} values drop to <20 mL/g when they are present. The most promising PLMs were the Cr, Ti, Zr, and Si pillared tantalum tungstate. The K{sub d} values for Sr{sup 2+} and Ba{sup 2+} show a strong pH dependence; K{sub d} values increase to >10{sup 4} above pH 12. The general surface complexation mechanism explains the sorption of these cations on PLMs.

Schroeder, N.C.; Wade, K.L.; Morgan, D.M. [and others

1998-12-31

63

Alternating Current Corrosion of Aluminium Sacrificial Anodes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

64

Atomic layer deposition of nanostructured materials  

CERN Multimedia

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

65

Atomic Layer Deposition of Multicomponent Oxide Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Atomic layer deposition (ALD) is a method for thin film deposition which has been extensively studied for binary oxide thin film growth. Studies on multicomponent oxide growth by ALD remain relatively few owing to the increased number of factors that come into play when more than one metal is employed. More metal precursors are required, and the surface may change significantly during successive stages of the growth. Multicomponent oxide thin films can be prepared in a well-controlled way as ...

Vehkama?ki, Marko

2007-01-01

66

Epitaxial Growth of GaN-based LEDs on Simple Sacrificial Substrates  

Energy Technology Data Exchange (ETDEWEB)

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

Ian Ferguson; Chris Summers

2009-12-31

67

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

68

Method for depositing layers of high quality semiconductor material  

Energy Technology Data Exchange (ETDEWEB)

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

69

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

70

Examples of material solutions in bimetallic layered castings  

Directory of Open Access Journals (Sweden)

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

S. Tenerowicz

2011-07-01

71

Love wave propagation in functionally graded piezoelectric material layer.  

Science.gov (United States)

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

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

2007-03-01

72

Electromagnetic cloaking by layered structure of homogeneous isotropic materials  

CERN Multimedia

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

Huang, Ying; Jian, Tian

2007-01-01

73

Novel material properties of strained-layer superlattices  

Energy Technology Data Exchange (ETDEWEB)

Strained-layer superlattices (SLS's) are high quality structures grown from lattice-mismatched semiconductor materials. Recent Sandia studies have demonstrated that a variety of SLS material properties can be tailored through the flexible choice of layer materials and thicknesses and through the use of quantum size effects, zone folding effects, and strain effects. The use of strained layers in SLS's allows these structures to exhibit a number of novel features. Examples of these features include: independently variable band gap and lattice constant using mismatched ternaries; strain-induced band gap shifts; and strain-modified effective masses. These features provide the opportunity for a variety of fundamental and applied materials studies using SLS systems.

Osbourn, G.C.

1985-05-01

74

Incorporating microorganisms into polymer layers provides bioinspired functional living materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

2012-01-01

75

Sacrificial template method of fabricating a nanotube  

Energy Technology Data Exchange (ETDEWEB)

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 <001> 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

76

Incorporating microorganisms into polymer layers provides bioinspired functional living materials.  

Science.gov (United States)

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-cleaning capability when subjected to standardized food spill. Fungal growth and reproduction were observed in between two specifically adapted polymer layers. Gas exchange for breathing and transport of nutrient through a nano-porous top layer allowed selective intake of food whilst limiting the microorganism to dwell exclusively in between a confined, well-enclosed area of the material. We demonstrated a design of such living materials and showed both active (eating) and waiting (dormant, hibernation) states with additional recovery for reinitiation of a new active state by observing the metabolic activity over two full nutrition cycles of the living material (active, hibernation, reactivation). This novel class of living materials can be expected to provide nonclassical solutions in consumer goods such as packaging, indoor surfaces, and in biotechnology. PMID:22198770

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

2012-01-01

77

Structure, Orientation and Stability of Lysozyme Confined in layered Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Balme, Se?bastien; Gue?gan, Re?gis; Janot, Jean-marc; Jaber, Maguy; Lepoitevin, Mathilde; Dejardin, Philippe; Bourrat, Xavier; Motelica-heino, Mikael

2013-01-01

78

Superconductivity in layered materials with intralayer and interlayer couplings  

Energy Technology Data Exchange (ETDEWEB)

A study of the superconductivity of layered materials is reported. We treat very thin layers and assume two interactions, intralayer and interlayer. A two-component Ginzburg-Landau equation is derived taking into account two types of order parameters. T/sub c/ is raised by the cooperation of the two interactions. H/sub c//sub 2/ shows anisotropic behavior not only due to the anisotropy of the one-electron state but also due to the anisotropy of the pairing interaction.

Suwa, Y.; Tanaka, Y.; Tsukada, M.

1989-05-01

79

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

2009-10-02

80

Atomic Layer Deposition for the Conformal Coating of Nanoporous Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. Additio...

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

2006-01-01

 
 
 
 
81

New buffer layer materials for CIGS solar cells  

Energy Technology Data Exchange (ETDEWEB)

The compound semiconductor CuIn{sub x}Ga{sub (1-x)}Se{sub 2} (CIGSE) are used as absorber material in thin-film photovoltaic cells. In conventional CIGSE based solar cells a thin CdS layer (buffer) significantly improves the photovoltaic performance and efficiencies up to 19.9% have been realized. Since Cd is a toxic heavy metal there is a demand for suitable substitute materials. The first requirements for these materials are an adequate band gap, a crystal structure compatible to that of CIGSE, and an n-type conductivity. An interesting class of materials are half-Heuslers, which are ternary compounds with a C1b MgAgAs structure. For many half-Heusler compounds the crystal structure matches well with the layer of the tetragonal CIGS unit cell. Using ab initio calculations based on B3LYP hybrid functionals, we have studied electronic properties of the most promising half-Heusler materials. Our results affirm the band gap rule for 8-electron half- Heuslers presented.

Gruhn, Thomas; Felser, Claudia [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg University, Mainz (Germany); Kieven, David [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany)

2009-07-01

82

Investigations of sacrificial and plasma mirrors on the HELEN laser CPA beam  

Science.gov (United States)

The performance of sacrificial and plasma mirrors has been investigated on the HELEN laser chirped pulse amplification [CPA] beam line. Sacrificial mirrors are initially highly reflective surfaces that degrade during the course of a pulsed laser experiment. They are being considered for protecting the off axis parabolic surfaces used to focus CPA lasers from plasma physics target generated debris and shrapnel. Plasma mirrors are initially low reflectivity surfaces that transmit low intensity beams but produce a reflecting plasma surface during the course of the laser pulse. They are being investigated to prevent prepulse effects in plasma physics experiments and increase the contrast ratio of the incident laser beam.The sacrificial mirrors were operated at 45 degrees angle of incidence and an average input beam diameter of ~14 mm with intensities in the range 8 TW/cm2 to 44 TW/cm2. Dielectric protected silver and gold coatings as well as dielectric multi layers were studied as the mirror surfaces for directing all of the short pulse [500fs] laser beams onto tantalum foil targets of 10 microns thickness. Proton emissions from the foils monitored by radiochromic film were used to evaluate the beam irradiance achieved from the mirror surfaces. Glass witness plates were used to evaluate debris and shrapnel emissions from the mirror surfaces, the diagnostics and the target foils. The plasma mirrors were operated in a similar configuration but with beam diameters of ~8mm and irradiances of 57 TW/cm2 to 235 TW/cm2. Uncoated and sol gel anti-reflection coated fused silica were used as the high intensity mirror surfaces. The influence of surface coating on laser damage morphology will be described as well as post shot inspection of debris distributions.

Andrew, James E.; Comley, Andrew J.

2007-01-01

83

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

Science.gov (United States)

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

84

Gamma radiation transport and scattering in layers of material  

International Nuclear Information System (INIS)

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

1982-09-09

85

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

86

Porous manganese oxide octahedral molecular sieves and octahedral layered materials.  

Science.gov (United States)

This Account first gives a historical overview of the development of octahedral molecular sieve (OMS) and octahedral layer (OL) materials based on porous mixed-valent manganese oxides. Unique properties of such systems include excellent semiconductivity and porosity. Materials that are conducting and porous are rare and can offer novel properties not normally available with most molecular sieve materials. The good semiconductivity of OMS and OL systems not only permits potential applications of the conductivity of these materials but also allows characterization of these systems where charging effects are often a problem. Porous manganese oxide natural materials are found as manganese nodules, and these materials when dredged from the ocean floors have been used as excellent adsorbents of metals such as from electroplating wastes and have been shown to be excellent catalysts. Rational for synthesis of novel OMS and OL materials is related to the superb conductivity, microporosity, and catalytic activity of these natural materials. The natural systems are often found as mixtures, are poorly crystalline, and have incredibly diverse compositions due to exposure to various aqueous environments in nature. Such exposure allows ion exchange to occur. Preparation of pure crystalline OL and OMS systems is one of the very significant goals of this work. The status of this research area is one of moderate development. Opportunities exist for preparation of a multitude of novel materials. Some applications of these materials have recently been achieved primarily in the area of catalysis and membranes, and others such as sensors and adsorptive systems are likely. Characterization studies are becoming more sophisticated as new materials and proper preparation of materials for such characterization studies are being done. The research area involved in this work is solid state chemistry. The fields of materials synthesis, characterization, and applications of materials are all important in developments of this field. Researchers in chemistry, chemical engineering, materials science, physics, and biological sciences are actively pursuing research in this area. The most significant results found in this work are related to the novel structural and physical properties of porous manganese oxide materials. Variable pore size materials have been synthesized using structure directors and with a variety of synthetic methodologies. Transformations of tunnel materials with temperature and in specific atmosphere have recently been studied with in situ synchrotron methods. Conductivities of these materials appear to be related to the structural properties of these systems with more open structures being less conductive. Catalytic properties of these OMS and OL materials have been shown to be related to the redox cycling of various oxidations states of manganese such as Mn2+, Mn3+, and Mn4+. Chemists interested in synthesis of new materials, the chemistry of solids, enhancing the rates of catalytic reactions, and finding new applications of materials would be interested in these novel materials. Fundamental properties of electron transfer are critical to this research. Concepts of nonstoichiometry, defects, oxygen vacancies, and intermediates are fundamental to many of the syntheses, characterization, and applications such as fuel cells, catalysis, adsorption, sensors, batteries, and related applications. PMID:18232663

Suib, Steven L

2008-04-01

87

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

88

Studies of layered and pillared manganese oxide materials  

Science.gov (United States)

Synthetic Birnessite, an octahedral layered manganese oxide material called OL-1 was synthesized with Na+, K+, Na +/Mg2+, K+/Mg2+, Na +/K+ ions as interlayer cations by redox reactions between permanganate and alcohols in a strong basic media. Chromia pillared OL-1s were prepared under reflux conditions using trinuclear chromium hydroxyl acetate as a pillaring agent followed by calcination in a N2 atmosphere at 200°C. Vanadium oxide pillared OL-1s were obtained by intercalating neutral vanadyl acetylacetonate (VOacac) or vanadium acetylacetonate (Vacac) into the interlayer of OL-1 and subsequently calcining in air at 300°C. The synthesis procedures were monitored using X-ray diffraction studies. The resultant materials were characterized by XRD, X-ray absorption, X-ray photoelectron spectra, FTIR, UV-VIS, inductively coupled plasma, transmission electron spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis, potentiometric titration, thermal analyses, TPD measurements, BET surface area and pore size distribution measurements. OL-1 materials prepared using this alcohol route showed enhanced thermal stabilities and increased Mg accommodation compared to OL-1s prepared with other methods. Based on the analysis methods developed here, Na-OL-1 exhibited recoverable and reversible structural and surface O2 oxygen species while K-OL-1 showed higher stability. Na-OL-1 had predominantly Bronsted acid sites resulting from OH groups bonded to Mn on Na-OL-1 surfaces, while the Na/Mg-OL-1 had mainly Lewis acid sites. Large porosity was obtained in chromia pillared OL-1 materials with a narrow pore size distribution centered around 18 A. Although these materials remained "amorphous" as determined by XRD after calcination, TEM morphology studies suggest that the materials were still layered. EXAFS studies indicated the formation of Cr-O-Mn bonds in the resultant materials via comer-shared linkages of CrO6 and MnO6 octahedra. Good crystallinity in VOacac intercalated OL-1 was achieved, which after calcination, led to the formation of mesoporous VOx pillared OL-1 materials with the pore diameters being in the range of 36 to 41 A. The intercalation of bulky neutral inorganic species into the interlayer of OL-1 through an exfoliation route simplified the pillaring process and preparative factors and made the process and pore sizes in the pillared materials controllable.

Ma, Ying

89

Universal method for creating optically active nanostructures on layered materials.  

Science.gov (United States)

The ability to form patterned surface nanostructures has revolutionized the miniaturization of electronics and led to the discovery of emergent behaviors unseen in macroscopic systems. However, the creation of such nanostructures typically requires multiple processing steps, a high level of technical expertise, and highly sophisticated equipment. In this work, we have discovered a simple method to create nanostructures with control size and positioning in a single processing step using a standard scanning electron microscope. The technique can be applied to a wide range of systems and was successful in every layered material tested. Patterned nanostructures were formed on graphite, topological insulators, novel superconductors, and layered transition metal dichalcogenides. The nanostructures were formed via the incorporation of carbon nanoparticles into the samples in a novel form of intercalation. It appears that the electron beam interacts with residual organic molecules available on the sample surface, making it possible for them to intercalate between the layers in their crystal structure and break down into carbon. These carbon nanoparticles have strong broad-wavelength interactions in the visible light range, making these nanostructures easily detectable in an optical microscope and of interest for a range of nanoscale electro-optical devices. PMID:24793140

Kidd, Timothy E; O'Shea, Aaron; Beck, Benjamin; He, Rui; Delaney, Conor; Shand, Paul M; Strauss, Laura H; Stollenwerk, Andrew; Hurley, Noah; Spurgeon, Kyle; Gu, Genda

2014-05-27

90

Arhaeoastronomical analysis of Levinsadovka sacrificial complex (South Russia)  

CERN Document Server

The article presents research data using arhaeoastronomical methods of Levinsadovka settlement sacrificial complex in Northern Black Sea coast. In this work, new method of accounting terrain elevations using topographic maps was developed in arhaeoastronomical studies. Calculations of azimuths of the sun and moon rise and set in the astronomically significant moments of the year were made and astronomical regularities in the organization of the sacrificial complex identified. Related to the moon directions, as the most dedicated, identified. Revealed that the stone tools and fragments, used as sacrifices, mark the direction to the northern minor standstill moonrise. A similar situation was found on two archaeological sites: in Bezymennoye II settlement South sanctuary and in Pustynka settlement religious building. Drawing on ethnographic and folklore data, it is concluded about semiotic connection of stone tools, found in these religious constructions, with the "thunderstones" and meteorites.

Vodolazhskaya, Larisa

2013-01-01

91

Cathodic protection using sacrificial magnesium anodes in prestressed concrete pipelines  

Energy Technology Data Exchange (ETDEWEB)

Two cases of corrosion caused failures in prestressed concrete cylinder pipelines are presented. After determining the nature of the corrosion and its causes, cathodic protection was taken as the only tool that could be applied to try to save the pipeline. This paper describes the methods used to apply cathodic protection using sacrificial magnesium anodes to a pipeline of 800 pipe sections. Also presented are the results of the first year of application.

Peris, M.G. [Canal de Isabel II, Madrid (Spain); Guillen, M.A. [Inst. Espanol de Corrosion, Madrid (Spain)

1994-12-31

92

Ion doping of surface layers in conducting electrical materials  

International Nuclear Information System (INIS)

The presented article gives basic component elements of an implanter MKPCz-99, its parameters and methods for doping surface layers of conducting electrical materials. The discussed device makes possible to dope the materials with ions of gaseous elements. At the application of cones made of solid-element sheets it is possible to perform doping with atoms that do not chemically react with the modified material. By performing voltage drop measurements with a specialized circuit between a movable testing electrode and the modified sample the dependence of transition resistance on pressure force of the testing electrode on the sample can be determined. The testing can be performed at the current passage of a determined value for surfaces modified with ions of gaseous elements or atoms of solid elements. A computer stand for switch testing makes possible to measure temperature of switch contacts and voltage drop at the contact and thereby to determine contact resistance of a switch depending on the number of switch cycles (ON-OFF). Pattern recording of current and voltage at the switch contacts and the application of an adequate computer software makes possible to determined the value of energy between fixed and moving contacts at their getting apart. In order to eliminate action of the environment onto the switch operation measurements can be performed at placing the tested switch together with the driving system in an atmosphere of noble gas like argon. (authors)

2009-09-01

93

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

Science.gov (United States)

Complex coacervates prepared from poly(aspartic acid) (polyAsp) and poly-l-histidine (polyHis) were investigated as models of the metastable protein phases used in the formation of biological structures such as squid beak. When mixed, polyHis and polyAsp form coacervates whereas poly-l-glutamic acid (polyGlu) forms precipitates with polyHis. Layer-by-layer (LbL) structures of polyHis-polyAsp on gold substrates were compared with those of precipitate-forming polyHis-polyGlu by monitoring with iSPR and QCM-D. PolyHis-polyAsp LbL was found to be stiffer than polyHis-polyGlu LbL with most water evicted from the structure but with sufficient interfacial water remaining for molecular rearrangement to occur. This thin layer is believed to be fluid and like preformed coacervate films, capable of spreading over both hydrophilic ethylene glycol as well as hydrophobic monolayers. These results suggest that coacervate-forming polyelectrolytes deserve consideration for potential LbL applications and point to LbL as an important process by which biological materials form. PMID:23600626

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

2013-06-10

94

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.

95

Formation of elongated fascicle-inspired 3D tissues consisting of high-density, aligned cells using sacrificial outer molding.  

Science.gov (United States)

The majority of muscles, nerves, and tendons are composed of fiber-like fascicle morphology. Each fascicle has a) elongated cells highly aligned with the length of the construct, b) a high volumetric cell density, and c) a high length-to-width ratio with a diameter small enough to facilitate perfusion. Fiber-like fascicles are important building blocks for forming tissues of various sizes and cross-sectional shapes, yet no effective technology is currently available for producing long and thin fascicle-like constructs with aligned, high-density cells. Here we present a method for molding cell-laden hydrogels that generate cylindrical tissue structures that are ~100 ?m in diameter with an extremely high length to diameter ratio (>100 : 1). Using this method we have successfully created skeletal muscle tissue with a high volumetric density (~50%) and perfect cell alignment along the axis. A new molding technique, sacrificial outer molding, allows us to i) create a long and thin cylindrical cavity of the desired size in a sacrificial mold that is solid at a low temperature, ii) release gelling agents from the sacrificial mold material after the cell-laden hydrogel is injected into fiber cavities, iii) generate a uniform axial tension between anchor points at both ends that promotes cell alignment and maturation, and iv) perfuse the tissue effectively by exposing it to media after melting the sacrificial outer mold at 37 °C. The effects of key parameters and conditions, including initial cavity diameter, axial tension, and concentrations of the hydrogel and gelling agent upon tissue compaction, volumetric cell density, and cell alignment are presented. PMID:24744046

Neal, Devin; Sakar, Mahmut Selman; Ong, Lee-Ling S; Harry Asada, H

2014-06-01

96

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

97

Tritium permeation inhibiting layer for high-temperature materials  

International Nuclear Information System (INIS)

In order to prevent tritium contaminations, several spinel layers, which are separated by metallic intermediate layers (Fe, Ni) and covered by a metal layer (Ni), are deposited on the reactor components of a HTR which consist, e.g., of a steel with a high nickel content. The spinel layers are between 3 and 2 m thick. With this measure, tritium permeation could be reduced by a factor of 3 x 10 (steam spinellisation). (orig./PW)

1977-02-01

98

Materiales laminares pilareados: preparación y propiedades / Pillared layered materials: preparation and properties  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Spanish Abstract in spanish [...] Abstract in english The structure of several types of layered materials will be described. These include clays, layered double hydroxides, group IV metal phosphates and other layered materials. The preparation of the pillared materials and pillaring agents will be presented along with a description of the properties an [...] d applications of the products.

Sibele B. C., Pergher; Avelino, Corma; Vicente, Fornes.

99

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 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. 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.

Chaparro Amaya, Adolfo.

100

Laser modification of surface layer properties in conducting materials  

International Nuclear Information System (INIS)

This paper presents results of modification of properties for surface layers, obtained during optimized laser alloying of metals significant in electrical engineering. Systems with continuous, quasi-continuous and pulsed laser beam and different wave length were used for experiments. The structure and composition of alloyed layers was examined by means of SEM-microscopy and EDX analyser. The changes of electrical resistivity after laser alloying were measured in the temperature range 77-450 K. It was showed, that there is possible formation of alloyed layers for metals with limited solubility (Ag-Sn), insoluble metals (Mo-Au, Cu-Cr), and even immiscible metals (Ni-Au, Ag-Ni). The alloyed layers with non-metallic additions (oxide) can be achieved too. The investigations showed, how by employment of different laser beams and various methods for supplying of alloying elements it is possible to achieve alloyed layers with strongly modified properties, especially electrical resistivity. (author)

2002-09-23

 
 
 
 
101

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

Energy Technology Data Exchange (ETDEWEB)

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; Lillo, Thomas M [Idaho Falls, ID; Chu, Henry S [Idaho Falls, ID

2010-11-16

102

Electrochemical behavior of Al—basic sacrificial anode at estuary  

Science.gov (United States)

The Al—basic sacrificial anode is widely used to protect steel construction from corrosion in seawater, but is not suitable for protecting steel in freshwater. In the estuary area, seawater and freshwater mix and different seawater salinity can be formed in different mixing sites between freshwater and seawater. Based on the requirements of the Shengli Petroleum Administrative Bureau of China, the effect of seawater salinity on electrochemical properties of Al—basic anode was studied under laboratory conditions by the method given in National Standard GB 4948-85 (China Starndard Bureau, 1985). No obvious effect was found when seawater salinity was 30 to 10, but obvious effect on anodic open circuit potential, closed circuit potential and current efficiency was found when seawater salinity was 5. These values are lower than those given in the National Standard.

Zhang, Jing-Lei; Hou, Bao-Rong; Li, Hong-Ling; Yang, Fang-Ying; Xie, Xiao-Bo

1996-09-01

103

Experiences in retrofitting sacrificial anodes in offshore Arabian Gulf  

Energy Technology Data Exchange (ETDEWEB)

An analysis was made of the cathodic protection systems of fifteen (15) fixed offshore platforms. These steel template structures are located in the warm waters off the coast of the United Arab Emirates with water depth varying between 125 and 185 feet. The operator employs a systematic survey program to monitor the corrosion protection systems including the assessment of sacrificial anode depletion, and measurement of the anode and platform potentials. These data are used to design new anode retrofits for the older structures to extend the life of the CP systems. This paper presents an analysis of the field survey measurements, the method used to evaluate when new anodes are required, how many are needed, and where to locate retrofit anodes.

Kiefer, J.H. [Conoco Inc., Houston, TX (United States); Thomason, W.H. [Conoco Inc., Ponca City, OK (United States); Alansari, N.G. [Dubai Petroleum Co. (United Arab Emirates)

1998-12-31

104

Identification Of Elastic Properties Of Layered Composite Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this thesis the problems of identification accuracy of elastic properties of materials are examined. The main object of study is samples of various materials and their elastic properties. This is an important subject of theoretical studies of various materials. The main thesis objective is to create an effective technology for precise identification of all the elastic characteristics of the sample. The de-veloped algorithms are to be applied in the material manufacturing industry. Thesis a...

Ragauskas, Paulius

2010-01-01

105

Method for forming a layer of synthetic corrosion products on tubing surfaces  

Energy Technology Data Exchange (ETDEWEB)

A method is provided for forming a synthetic corrosion product layer on tube surfaces. The method utilizes two dissimilar materials with different coefficients of thermal expansion. An object tube and sacrificial tube are positioned one inside the other such that an annular region is created between the two tubes' surfaces. A slurry of synthetic corrosion products is injected into this annular region and the assembly is heat treated. This heat causes the tubes to expand, the inner tube with the higher coefficient of expansion expanding more than the outer tube, thereby creating internal pressures which consolidate the corrosion products and adhere the corrosion products to the tubing surfaces. The sacrificial tube may then be removed by conventional chemical etching or mechanical methods.

Lane, Michael H. (Clifton Park, NY); Salamon, Eugene J. M. (Clifton Park, NY)

1996-01-01

106

Microstrip antennas on/in anisotropic material layers  

Science.gov (United States)

Accurate fullwave analyses of microstrip dipoles on multi-layer substrates with generalized anisotropic permittivity and permeability have been developed. The solution to the problem of microstrip dipoles on/in gyrotropic substrates has been obtained. The potential of electronically shaped, scanned, and gain enhanced element factors with ferrite substrates has been theoretically demonstrated. The scattering and radiation problems were solved. The use of biased ferrite substrates to simultaneously reduce RCS and preserve antenna in-band gain has also been described. Infinite phased arrays of microstrip dipoles and probe-fed patches on general anisotropic multi-layer substrates have been analyzed. All the solutions involve the dyadic Green's function for the anisotropic layered structure and the application of the method of moments to an electric field integral equation.

Yang, Hung-Yu; Castaneda, Jesse A.; Nakatani, Akifumi

1992-11-01

107

Infrared ellipsometry of nanometric anisotropic dielectric layers on absorbing materials  

Science.gov (United States)

An inversion problem of infrared ellipsometry is resolved on the basis of a fresh mathematical approach, which does not use the traditional regression analysis for data handling and has no need of initial guesses for the desired parameters. It is shown that obtained simple analytical equations for ellipsometric quantities open up new possibilities for determining optical parameters of an anisotropic ultrathin layer. The novel method possesses very high sensitivity because it is based on the phase conversion measurements of polarized reflected light. The method is tested using a numerical simulation and the results demonstrate clearly that it is successfully applicable for nanometric layers in the infrared spectral region.

Adamson, Peep

2014-05-01

108

UV nanoimprint materials: Surface energies, residual layers, and imprint quality  

Digital Repository Infrastructure Vision for European Research (DRIVER)

UV nanoimprint lithography is attracting more and more interest, because it has the potential of becoming a high-resolution, low-cost patterning technique. The availability of suitable UV curing materials is mandatory for successful imprinting. Within this work, a systematic investigation of commercially available photo curing materials was conducted to provide an overview of the properties of these materials. Their wetting behavior with respect to different substrate surfaces was characteriz...

Schmitt, H.; Frey, L.; Ryssel, H.; Rommel, M.; Lehrer, C.

2007-01-01

109

ZnO layers grown by Atomic Layer Deposition: A new material for transparent conductive oxide  

Energy Technology Data Exchange (ETDEWEB)

We demonstrate possibility of a control (by selection of zinc precursors and variation of a growth temperature) of electrical properties of ZnO films grown by Atomic Layer Deposition (ALD). ZnO films grown by ALD are used in test photovoltaic devices (solar cells) as transparent conductive oxides for upper, transparent layer in inorganic and organic solar cells, and as n-type partners of p-type CdTe.

Godlewski, M., E-mail: godlew@ifpan.edu.p [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, Warsaw (Poland); Department of Mathematics and Natural Sciences, College of Science, Cardinal Stefan Wyszynski University, Warsaw (Poland); Guziewicz, E.; Luka, G.; Krajewski, T. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, Warsaw (Poland); Lukasiewicz, M.; Wachnicki, L.; Wachnicka, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, Warsaw (Poland); Department of Mathematics and Natural Sciences, College of Science, Cardinal Stefan Wyszynski University, Warsaw (Poland); Kopalko, K. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, Warsaw (Poland); Sarem, A.; Dalati, B. [Department of Physics, Faculty of Science, Tishreen University, Latakia (Syrian Arab Republic)

2009-12-15

110

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Malecha, Karol; Maeder, Thomas; Jacq, Caroline

2012-01-01

111

Abradable layer for a flow machine, comprises a particle composite material and a composite that contains ceramic particles with surface functional layers  

DEFF Research Database (Denmark)

A machine abradable layer (10), comprises a particle composite material, and a composite (1) that contains ceramic particles (2) with functional layers on the surface (20). The layers form stable intermediary phases at high operating temperatures. The intermediary phases are partly formed by a chemical reaction between a precursor and the ceramic particles. The material is used as an abradable layer for a machine, eg a gas turbine, turbo compressor etc. The layer can operate at high temperatures.

Wilson, Scott unknown

112

Engineering interconnected 3D vascular networks in hydrogels using molded sodium alginate lattice as the sacrificial template.  

Science.gov (United States)

Engineering 3D perfusable vascular networks in vitro and reproducing the physiological environment of blood vessels is very challenging for tissue engineering and investigation of blood vessel function. Here, we engineer interconnected 3D microfluidic vascular networks in hydrogels using molded sodium alginate lattice as sacrificial templates. The sacrificial templates are rapidly replicated in polydimethylsiloxane (PDMS) microfluidic chips via Ca(2+)-crosslinking and then fully encapsulated in hydrogels. Interconnected channels with well controlled size and morphology are obtained by dissolving the monolayer or multilayer templates with EDTA solution. The human umbilical vein endothelial cells (HUVECs) are cultured on the channel linings and proliferated to form vascular lumens. The strong cell adhesion capability and adaptive response to shear stress demonstrate the excellent cytocompatibility of both the template and template-sacrificing process. Furthermore, the barrier function of the endothelial layer is characterized and the results show that a confluent endothelial monolayer is fully developed. Taken together, we develop a facile and rapid approach to engineer a vascular model that could be potentially used in physiological studies of vascular functions and vascular tissue engineering. PMID:24887141

Wang, Xue-Ying; Jin, Zi-He; Gan, Bo-Wen; Lv, Song-Wei; Xie, Min; Huang, Wei-Hua

2014-08-01

113

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

114

Surface layer properties of the workpiece material in high performance grinding  

Directory of Open Access Journals (Sweden)

Full Text Available This paper focuses on the development of high temperatures in the cutting zone during high performance grinding. In order to identify the infl uence of grinding temperature on surface integrity, temperatures were measured in the workpiece surface layer under diff erent machining conditions. Beside this, under the same conditions, the surface layer properties of the workpiece material were determined through metallographic examination. Microstructureand microhardness of the workpiece surface layer, as well as the burned surfaces and microcracks phenomena were investigated. The conducted experimental investigations allow the surface layer properties of the workpiece material in high performance grinding to be defined.

M. Gostimirovi?

2012-01-01

115

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 restricted shipments of Krypton 85 and then NRC certification for unrestricted shipments

1989-03-02

116

Selection of elastomeric materials for compliant-layered total hip arthroplasty.  

Science.gov (United States)

A selection procedure has been developed to identify suitable commercial materials for use in compliant-layer artificial hip joints. Mechanical requirements, notably hardness and strength, as well as biocompatibility, constituted the specification for the compliant layer. Applying these constraints, candidate materials were identified in a broad range of polymeric material classes. Detailed sourcing and literature searching helped to identify materials appropriate to the application, with suitable mechanical and physical properties, as well as a history of successful clinical use. Some likely materials were identified but were prohibited from further consideration by limited commercial availability. Physical and mechanical characterization together with literature data were used to determine the relative ranking of the candidate materials and through a weighted materials property selection procedure the materials of choice were identified. The linear segmented aromatic polyurethanes, Tecothane 1085 and Estane 5714F1, emerged as the preferred materials. PMID:11905561

Quigley, F P; Buggy, M; Birkinshaw, C

2002-01-01

117

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

118

Electroplex emission from bi-layer blue emitting organic materials  

Energy Technology Data Exchange (ETDEWEB)

Electroluminescence (EL) and photoluminescence (PL) spectra of an electron donor, an (poly(N-vinylcarbazole) (PVK))/electron acceptor, and a (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD)) bi-layer solid film are analysed. The EL emission peak has an apparent red-shift with the increase of driving voltage. There maybe exist an electroplex emission between the PVK and PBD interface under high electric field strength. According to their energy level, the electroplex emission peak should locate at 460 nm. There are great spectra overlapping between PVK emission and electroplex emission, and the ratio of electroplex emission intensity to exciton emission intensity (I{sub electroplex}/I{sub exciton}) increases from 0.38 at 10 to 0.81 at 16 V. Therefore the measured emission peaks continuously shift from 410 nm at 10 V to 445 nm at 16 V.

Zhang Fujun; Zhao Suling; Zhao Dewei; Jiang Weiwei; Li Yuan; Yuan Guangcai; Zhu Haina; Xu Zheng [Key Laboratory for Information Storage, Display and Materials, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China)

2007-04-15

119

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

120

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

International Nuclear Information System (INIS)

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 (O2TRs) 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 O2TRs 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.

2011-03-01

 
 
 
 
121

Ultrasonic investigation of the boundary layer of structural material-heavy liquid metal coolant  

International Nuclear Information System (INIS)

The work is aimed at accomplishing the ultrasonic (US) study on properties of the boundary layer area of the heavy liquid metal coolant (HLMC) contact with structural materials. Dependences of the US signal amplitude change on the hard metal wetting through the liquid one by argon and hydrogen bubbling through the liquid metal layer are studied. The data obtained make it possible to design the model of the HLMC boundary layer with metal

2004-12-01

122

Defect engineering of 2D monatomic-layer materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Atomic-thick monolayer two-dimensional materials present advantageous properties compared to their bulk counterparts. The properties and behavior of these monolayers can be modified by introducing defects, namely defect engineering. In this paper, we review a group of common two-dimensional crystals, including graphene, graphyne, graphdiyne, graphn-yne, silicene, germanene, hexagonal boron nitride monolayers and MoS2 monolayers, focusing on the effect of the defect engineering on these two-di...

Peng, Q.; Crean, J.; Dearden, A. K.; Huang, C.; Wen, X.; Bordas, Ste?phane; De, S.

2013-01-01

123

Silk as a biocohesive sacrificial binder in the fabrication of hydroxyapatite load bearing scaffolds.  

Science.gov (United States)

Limitations of current clinical methods for bone repair continue to fuel the demand for a high strength, bioactive bone replacement material. Recent attempts to produce porous scaffolds for bone regeneration have been limited by the intrinsic weakness associated with high porosity materials. In this study, ceramic scaffold fabrication techniques for potential use in load-bearing bone repairs have been developed using naturally derived silk from Bombyx mori. Silk was first employed for ceramic grain consolidation during green body formation, and later as a sacrificial polymer to impart porosity during sintering. These techniques allowed preparation of hydroxyapatite (HA) scaffolds that exhibited a wide range of mechanical and porosity profiles, with some displaying unusually high compressive strength up to 152.4 ± 9.1 MPa. Results showed that the scaffolds exhibited a wide range of compressive strengths and moduli (8.7 ± 2.7 MPa to 152.4 ± 9.1 MPa and 0.3 ± 0.1 GPa to 8.6 ± 0.3 GPa) with total porosities of up to 62.9 ± 2.7% depending on the parameters used for fabrication. Moreover, HA-silk scaffolds could be molded into large, complex shapes, and further machined post-sinter to generate specific three-dimensional geometries. Scaffolds supported bone marrow-derived mesenchymal stem cell attachment and proliferation, with no signs of cytotoxicity. Therefore, silk-fabricated HA scaffolds show promise for load bearing bone repair and regeneration needs. PMID:24881027

McNamara, Stephanie L; Rnjak-Kovacina, Jelena; Schmidt, Daniel F; Lo, Tim J; Kaplan, David L

2014-08-01

124

Proactive materials aging management and multi-layered maintenance  

International Nuclear Information System (INIS)

Long term operation of NPP has been receiving a great concern based upon the plant operation experiences and progressive improvement in countermeasures and mitigations. At the same time of this LTO movement, proactive materials aging management is also receiving a great concern to realize the LTO in NPP. Recent PMDM activities in Japan as well as some international one are reviewed and a necessity of an international cooperation is emphasized in relation to reliable maintenance performance connected from the top of the organization to operators and maintenance engineers at plant sites. (author)

2009-08-01

125

Thermomechanical Response of Layered Materials. Final technical report  

Energy Technology Data Exchange (ETDEWEB)

A new experimental technique involving instrumented indentation was demonstrated for the specific purpose of calibrating certain variations in elastic properties as a function of position in thermally sprayed and sintered materials. This work experimentally demonstrated for the first time that controlled gradients in elastic properties alone can lead to the suppression of damage and cracking during contact loading. New methods were developed in this work for the estimation of mechanical properties of ductile alloys and brittle ceramics by recourse to continuous measurements of load-penetration curves with spherical microindenters.

Suresh, S.

2000-05-20

126

Computer search for layer materials that maximize the reflectivity of X-ray multilayers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A database of atomic scattering factors [1] is exhaustively searched for layer materials that potentially maximize collection solid-angle in a multilayer mirror. Maximum attainable performance and corresponding materials are provided at 63 logarithmically spaced wavelengths in the soft X-ray region (6 A < A < 124 Å). Computationally rapid formulas that enable an efficient search are presented. Only a cursory screening is made of material suitability, but a number of possible materials combin...

Rosenbluth, A. E.

1988-01-01

127

Measurement and evaluation of the thermal diffusivity of two-layered materials  

Energy Technology Data Exchange (ETDEWEB)

Transient methods, such as those with pulse- or stepwise heating, have often been used to measure thermal diffusivity of various materials including layered composite materials. The aim of the present study is to investigate effects of various parameters on the measurement of thermal diffusivity when the transient methods are applied. Mainly a two-layered material in the pulsewise heating method is considered because of its simplicity and usefulness in identifying and determining the effects of the parameters. First, it has been shown that there exists a special condition for determining the thermal diffusivity of a component in the two-layered material whose other relevant thermophysical properties are known. Second, it has been shown that the thickness of the laser-beam absorption layer, which inevitably makes sample material into the two-layered material, may cause a relatively large error when the thermal diffusivity of the base material is high. Finally, it has been derived a definite relation between the apparent thermal diffusivity obtained from the temperature response and the mean thermal diffusivity, which has a physical meaning related to the thermal resistance. 4 refs., 8 figs., 2 tabs.

Araki, N.; Makino, A.; Mihara, J. (Shizuoka Univ., Hamamatsu (Japan))

1992-03-01

128

Effect of the AIN nucleation layer growth on AlN material quality  

Science.gov (United States)

AlN layers were grown by metalorganic vapor-phase epitaxy at high temperatures up to 1500 °C. Nucleation layer growth parameters and flow conditions before nucleation were changed and the effect on the AlN layer grown on top was studied. Structural analysis performed by high-resolution X-ray diffractometry and transmission electron microscopy showed that pregrowth conditions affect the material quality drastically. The best structural quality as indicated by a screw (including mixed) dislocation density of 8×10 8 cm -2, together with smooth surface morphology was found to result from simultaneous switching on of ammonia and TMAl at the beginning of nucleation layer growth.

Reentilä, O.; Brunner, F.; Knauer, A.; Mogilatenko, A.; Neumann, W.; Protzmann, H.; Heuken, M.; Kneissl, M.; Weyers, M.; Tränkle, G.

2008-11-01

129

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

Science.gov (United States)

Ten men (non-firefighters) completed a 110 min walking/recovery protocol (three 20-min exercise bouts, with recovery periods of 10, 20, and 20 min following successive bouts) in a thermoneutral laboratory while wearing firefighting personal protective equipment over one of four base layers: cotton, modacrylic, wool, and phase change material. There were no significant differences in changes in heart rate, core temperature, rating of perceived exertion, thermal discomfort, and thermal strain among base layers. Sticking to skin, coolness/hotness, and clothing humidity sensation were more favorable (p < 0.05) for wool compared with cotton; no significant differences were identified for the other 7 clothing sensations assessed. Separate materials performance testing of the individual base layers and firefighting ensembles (base layer + turnout gear) indicated differences in thermal protective performance and total heat loss among the base layers and among ensembles; however, differences in heat dissipation did not correspond with physiological responses during exercise or recovery. PMID:23849898

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

2014-05-01

130

Mortars for encapsulating sacrificial zinc anodes in reinforced concrete  

Energy Technology Data Exchange (ETDEWEB)

Expansion measurements, chemical analysis and petrography have been undertaken to assess a possible side-effect of using strongly alkaline additives (lithium hydroxide or sodium hydroxide) in encapsulating mortars used to promote the activity of sacrificial zinc anodes employed for galvanic cathodic protection of steel in concrete. Very high concentrations of lithium hydroxide in the encapsulating mortars were found to cause no deleterious expansion associated with alkali-silica reaction (ASR) in surrounding ''model'' concrete specimens even when the latter contained aggregate of known susceptibility to ASR and a near-threshold level of intrinsic alkalinity. Encapsulating mortars formulated with an equivalent molarity of sodium hydroxide, however, were found to induce significant expansion due to ASR in similar specimens. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Opferanoden aus Zink werden zum galvanischen kathodischen Schutz des Stahls in Beton in Moertel eingebettet, die stark alkalische Zusaetze (Lithiumhydroxid oder Natriumhydroxid) zur Verbesserung der Aktivitaet der Opferanode enthalten. Um moegliche Nebeneffekte dieser Zusaetze zu bestimmen, wurde die Ausdehnung, die chemische Zusammensetzung und die Petrographie der Einbettungsmoertel untersucht. Es zeigte sich, dass sehr hohe Konzentrationen an Lithiumhydroxid in den Einbettungsmoerteln keine schaedliche Ausdehnung in angrenzenden Modell-Beton-Proben aufgrund der Alkali-Silika-Reaktion (ASR) verursachten. Diese trat selbst dann nicht auf, wenn der umgebende Modell-Beton Zuschlaege mit bekannter Neigung zu ASR und eine intrinische Alkalinitaet in der Naehe des Schwellenwertes aufwies. Einbettungsmoertel, die mit einer aequivalenten Stoffmenge Natriumhydroxid angemacht wurden, verursachten in vergleichbaren Proben im Gegensatz dazu eine deutliche Ausdehnung aufgrund der ASR. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Jordan, Lee C.; Page, Christopher L. [University of Leeds, School of Civil Engineering, Leeds LS2 9JT (United Kingdom)

2003-06-01

131

Study on coated layer material performance of coated particle fuel FBR (1)  

International Nuclear Information System (INIS)

Design studies of 'Helium Gas Cooled Coated Particle Fuel FBR' are being conducted since it has the following superior features, and it is considered to be one of the most promising concepts in Feasibility Study on Commercialized Fast Reactor Cycle System in Japan (F/S). 1. Helium gas as coolant is applicable to a high temperature direct gas turbine cycle with high thermal efficiency, 2. Large heat capacity and large Doppler coefficient induced by coated layer material may achieve the attractive core safety characteristic such as so-called 'melt down proof' at the sever accident ('Depressurization accident + Without scram + Natural circulation'). As for the conventional design of coated particle fuel, TRISO fuel with SiC as main layer and PyC as buffer and surface protect layers has expressed a lot of excellent achievements in High Temperature Gas Reactor studies. However, it is impossible to directly use this fuel design in FBR, because high burn-up (?150GWd/t) aimed for economics demands higher strength, and high fast neutron fluence makes it difficult to adopt PyC as surface protect layer due to its dimensional instability in fast neutron spectrum. Therefore, materials with higher strength for main layer and alternative material for surface protect layer are necessary. Nevertheless, at present situation usable data of strength of coat ceramics besides SiC is scarce, and refractory metals as possible candidates of surface protect layer have little experience in fabrication. Based on these backgrounds, we have investigated characteristics of potential candidate coat materials (for main layer and surface protect layer) to understand the possibility of coating applications to the above described design concept in F/S, have selected some potential candidates, and have conducted tests of strength properties for main layer materials and tests of vapor deposition properties for surface protect layer materials. The results of these examinations come to the following conclusions. (1) As for TiN coat by the current coating technology, the Weibull modulus are gained to be 17.5 ? 22.3 (in conditions of thin layer and room temperature), and the strengths with 10-4 of coating layer failure reliability are evaluated to be 35.6 ? 100.1 kgf/mm2. These results reveal TiN has superior property in strength, and TiN is considered to be promising as main layer material. As for Si3N4 coat also, experimental results show capability to have superior property in strength. (2) Vapor deposition properties between W and main layer materials (TiN, SiC and Si3N4) are experimentally evaluated. These results reveal that the property by the conventional method is inferior, therefore, W is considered to require some additional studies to form a suitable coating layer. Contrary, Mo has superior vapor deposition properties on TiN, moreover the residual stress has tendency to be large in compression side. Therefore, Mo is considered to be promising as the surface protect layer material. (3) In the reference fuel design of F/S Phase I, if the maximum value of TiN coat strength evaluated in this study (100kgf/mm2) is applied for fuel integrity and optimization of thickness of buffer and main layer is conducted, the fuel volume fraction is evaluated to be increased up to 1.21 times of reference value. This reveals that the strength of TiN coat largely contribute to the core performance. (author)

2002-01-01

132

Electrochemical treatment and operating cost analysis of textile wastewater using sacrificial iron electrodes.  

Science.gov (United States)

Electrocoagulation (EC) method with iron electrode was used to treat the textile wastewater in a batch reactor. Iron electrode material was used as a sacrificial electrode in monopolar parallel mode in this study. The removal efficiencies of the wastewater by EC were affected by initial pH of the solution, current density, conductivity and time of electrolysis. Under the optimal experimental conditions (initial pH 6.9, current density of 10 mA/cm(2), conductivity of 3,990 microS/cm, and electrolysis time of 10 min), the treatment of textile wastewater by the EC process led to a removal capacity of 78% of chemical oxygen demand (COD) and 92% of turbidity. The energy and electrode consumptions at the optimum conditions were calculated to be 0.7 kWh/kg COD (1.7 kWh/m(3)) and 0.2 kgFe/kg COD (0.5 kgFe/m(3)), respectively. Moreover, the operating cost was calculated as 0.2 euro/kg removed COD or 0.5 euro/m(3) treated wastewater. Zeta potential measurement was used to determine the charge of particle formed during the EC which revealed that Fe(OH)(3) might be responsible for the EC process. PMID:19901457

Kobya, M; Demirbas, E; Akyol, A

2009-01-01

133

Analysis of compressive failure of layered materials by kink band broadening  

DEFF Research Database (Denmark)

Failure by steady state kink band broadening in uni-directional fibre composites or layered materials is analysed. An incremental scheme for calculation of kink band broadening stresses and lock-up conditions in the band for arbitrary material behaviour is presented. The method is illustrated by material data which are representative for polymer matrix composites for which experimental work exists. (C) 1999 Elsevier Science Ltd. All rights reserved.

Jensen, Henrik Myhre

1999-01-01

134

Superior hybrid cathode material containing lithium-excess layered material and graphene for lithium-ion batteries.  

Science.gov (United States)

Graphene-wrapped lithium-excess layered hybrid materials (Li(2)MnO(3)·LiMO(2), M = Mn, Ni, Co, hereafter abbreviated as LMNCO) have been synthesized and investigated as cathode materials for lithium-ion batteries. Cyclic voltammetry measurement shows a significant reduction of the reaction overpotential in benefit of the graphene conducting framework. The electrochemical impedance spectroscopy results reveal that the graphene can greatly reduce the cell resistance, especially the charge transfer resistance. Our investigation demonstrates that the graphene conducting framework can efficiently alleviate the polarization of pristine LMNCO material leading to an outstanding enhancement in cell performance and cycling stability. The superior electrochemical properties support the fine hybrid structure design by enwrapping active materials in graphene nanosheets for high-capacity and high-rate cathode materials. PMID:22931115

Jiang, Ke-Cheng; Wu, Xing-Long; Yin, Ya-Xia; Lee, Jong-Sook; Kim, Jaekook; Guo, Yu-Guo

2012-09-26

135

Luminescent materials based on Tb, Eu-containing layered double hydroxides  

International Nuclear Information System (INIS)

Luminescent materials on the basis of magnesium-aluminium layered double hydroxides with intercalated anionic complexes of terbium and europium picolinates were synthesized. Relying on data of spectroscopy, elementary and X-ray phase analyses, the change in the rare earth complex structure and metal/ligand ratio, depending on the hydroxide layer charge, determined by Mg/Al ratio in the double hydroxide, were ascertained. The values of quantum yields of luminescence for terbium-containing samples amounted to 30-50%

2004-05-01

136

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

137

Disrupting admicelle formation and preventing surfactant adsorption on metal oxide surfaces using sacrificial polyelectrolytes.  

Science.gov (United States)

The adsorption of anionic, cationic, and nonionic surfactants was measured on high-surface area silica and alumina nanoparticles when in the presence of the proposed polyelectrolyte sacrificial agents. Surfactant adsorption was characterized using two types of adsorption isotherms: one with constant polymer concentration and varying surfactant concentration, and another with a varying polymer concentration and constant surfactant concentration. Polystyrenesulfonate and Polydiallyl dimethylammonium chloride were tested as potential sacrificial agents on alumina and silica, respectively. Each surfactant/polymer system was allowed to reach equilibrium and supernatant surfactant concentrations were measured. This information was then plotted in order to determine what, if any, effect the proposed sacrificial agent had on the equilibrium adsorption. Results indicate that both of these polymers can have a large effect on total surfactant adsorption at a variety of surfactant concentrations. PMID:24826944

Weston, Javen S; Harwell, Jeffrey H; Shiau, Benjamin J; Kabir, Mahfuz

2014-06-10

138

Sacrificial charge and the spectral resolution performance of the Chandra Advanced CCD Imaging Spectrometer  

CERN Multimedia

Soon after launch, the Advanced CCD Imaging Spectrometer (ACIS), one of the focal plane instruments on the Chandra X-ray Observatory, suffered radiation damage from exposure to soft protons during passages through the Earth's radiation belts. The ACIS team is continuing to study the properties of the damage with an emphasis on developing techniques to mitigate charge transfer inefficiency (CTI) and spectral resolution degradation. A post-facto CTI corrector has been developed which can effectively recover much of the lost resolution. Any further improvements in performance will require knowledge of the location and amount of sacrificial charge - charge deposited along the readout path of an event which fills electron traps and changes CTI. We report on efforts by the ACIS Instrument team to characterize which charge traps cause performance degradation and the properties of the sacrificial charge seen on-orbit. We also report on attempts to correct X-ray pulseheights for the presence of sacrificial charge.

Grant, C E; La Marr, B; Bautz, M W; Grant, Catherine E.; Prigozhin, Gregory Y.; Marr, Beverly La; Bautz, Mark W.

2002-01-01

139

Anodic dissolution of Al sacrificial anodes in NaCl solution containing Ce  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} Ce improves the current efficiency of Al sacrificial anodes. {yields} Ce enhances a uniform attack on the surface of the Al alloy. {yields} The dissolution of the Al anode in chloride media initiates at precipitations where Ce is enriched. {yields} Ce enhances the activation on the surface of Al sacrificial anodes. - Abstract: The corrosion behaviour of Al-Zn-In sacrificial anodes has been investigated in a sodium chloride solution containing CeCl{sub 3}. Scanning electron microscopy, energy-dispersive X-ray analysis, and inductively coupled plasma mass spectrometry have been employed to gain knowledge of the micro-morphology and corrosion process of the Al alloy. Cerium, both as the alloy element and as the additive in the NaCl solution, improves the electrochemical properties of the Al-Zn-In alloy. The activation of Ce in the Al-Zn-In alloy in the NaCl solution has been studied.

Xiong, W. [Hubei Key Laboratory of Materials Chemistry and Service, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Qi, G.T., E-mail: qigongtai@mail.hust.edu.c [Hubei Key Laboratory of Materials Chemistry and Service, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Guo, X.P. [Hubei Key Laboratory of Materials Chemistry and Service, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Lu, Z.L. [Analytical and Testing Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

2011-04-15

140

Improvement of Cylindrical Cloak by Layered Structure of Homogeneous Isotropic Materials  

Directory of Open Access Journals (Sweden)

Full Text Available The perfect cylindrical cloak requires three spatial variant material parameters, which is very difficult to realize in practice [Science 312, 1780 (2006]. The approach of realizing the electromagnetic cloaking by concentric layered structures instead of using the metamaterial was presented [Optics Express, Vol. 15, No. 18 (2007]. We use the concentric layered structures to realize a simplified cylindrical cloak with improved parameters and an ideal cylindrical cloak with spatially invariant axial material parameters. Numerical simulation results validate that cloaking performance is significantly improved compared with previously proposed multilayered cloak.

Jun DING

2009-12-01

 
 
 
 
141

Requirements to materials of the antifrictional layer used at restoration of sliding bearings of crankshafts  

Directory of Open Access Journals (Sweden)

Full Text Available Now there are practical recommendations on restoration of sliding bear-ings based on long-term experience and corresponding scientific researches. However with the advent of new materials and technologies of restoration of an antifrictional layer there is a question on estimation of working capacity of the sliding bearing and definition of criteria of an opportunity of application of concrete antifrictional alloys for restoration of the antifrictional layer of sliding bearings. While using the antifrictional material different from design one, updating of productivity of the greasing system is required.

Matveev Yury Ivanovich

2009-04-01

142

Radiation-induced amorphization in Mo/Si nano-multi-layer materials  

International Nuclear Information System (INIS)

High-resolution microscopy was carried out for surveying atomistic mixing process in Mo-Si multi-layer materials, which is a candidate for soft x-ray mirror materials. Amorphization and shrinkage were observed during electron irradiation at room temperature. The Furor Transfer indicates that the multi-layer structure changed to be a amorphous structure. The Inverse Furor Transfer indicates random arraignment of the atoms with much compact packing. In this process the diffusion of Si atoms should be predominant for this amorphization. (author)

2007-03-01

143

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

Directory of Open Access Journals (Sweden)

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

Amanda Foster

2014-05-01

144

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

2006-05-10

145

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

International Nuclear Information System (INIS)

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

2009-04-15

146

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

147

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

148

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

Directory of Open Access Journals (Sweden)

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

Hany M. Zamel

2013-10-01

149

Method of interlayer tunneling for studies of layered high temperature superconductors and charge density wave materials  

Energy Technology Data Exchange (ETDEWEB)

A brief review of recent results on interlayer tunneling spectroscopy of layered high temperature superconductors (HTS) and charge density wave (CDW) materials is presented demonstrating high capability of this method for studies of both electron condensed states. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Latyshev, Yu.I.; Orlov, A.P. [IREE, RAS, Mokhovaya 11-7, 101999 Moscow (Russian Federation); Monceau, P. [CRTBT-CNRS, BP 166, 38042 Grenoble (France); Brazovskii, S.A. [LPTM-CNRS, Universite Paris-Sud, Paris 91405 (France); Yamashita, T. [NIMS, 305-0047 Ibaraki, Tsukuba (Japan); Bulaevskii, L.N. [Los Almos National Lab., Los Alamos, NM 87545 (United States)

2006-09-15

150

The collective mechanism of mass transport in surface layers of irradiated materials  

International Nuclear Information System (INIS)

The new collective mechanism of mass transport connected with diffusion of submicroscopic dislocation loops (SDL) which can act in surface layers of radiated crystalline materials is proposed and substantiated. It is shown that in real conditions SDL can diffuse essentially faster then point defects

2001-12-01

151

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)

2000-01-01

152

Study on coating layer of ceramic materials for SFR fuel slugs  

Energy Technology Data Exchange (ETDEWEB)

The plasma-sprayed coating can provide the crucible with a denser, more durable, coating layer, compared with the more friable coating layer formed by slurry-coating. Plasma-sprayed coatings are consolidated by mechanical interlocking of the molten particles impacting on the substrate and are dense by the heat applied by the plasma. The objective of this study is to develop a coating method and material for crucibles to prevent material interactions with the U-Zr/U-TRU-Zr fuels. Reducing these interactions will result in a fuel loss reduction. According to coating and U-Zr interaction results preformed in previous experience, Y{sub 2}O{sub 3}, TiC, and TaC coating materials were selected as promising coating materials Various combinations of coating conditions such as; coating thickness, double multi-layer coating methods were investigated to find the bonding effect on the substrate in pursuit of more effective ways to withstand the thermal stresses. To develop a coating method and material for crucibles to prevent material interactions with U-TRU-Zr fuels, the refractory coating was performed using vacuum plasma-sprayed method onto niobium rod. The various combinations of coating conditions such as; coating thickness, double multi-layer coating methods were investigated to find the bonding effect to withstand the thermal stress. Most of coating method samples did not maintain integrity in the U-Zr-RE melt because of the cracks or the microcracks of the coating layer, presumably formed from the thermal expansion difference. Only the double-layer coated rod with TaC and Y{sub 2}O{sub 3} powders, which is, which consists of vacuum plasma-sprayed TaC bond coating with the coating thickness of 100?m onto niobium rod and vacuum plasma-sprayed Y{sub 2}O{sub 3} coating with the coating thickness of 100?m on the top of the bond coating layer, survived the 2 cycles dipping test of U-Zr-RE melt this is likely caused by good adhesion of the TaC coating onto the niobium rod and the chemical inertness of Y{sub 2}O{sub 3} coating material in U-Zr-RE melt.

Song, Hoon; Kim, Jonghwan; Kim, Kihwan; Ko, Youngmo; Woo, Yoonmyung; Lee, Chanbock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-05-15

153

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

154

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

2000-01-01

155

A new low-cost, thick-film metallization transfer process onto PDMS using a sacrificial copper seed  

Science.gov (United States)

We present a new low cost microfabrication technology that utilizes a sacrificial conductive paint transfer method to realize thick film copper microstructures that are embedded in polydimethylsiloxane (PDMS). This process has reduced fabrication complexity and cost compared to existing metal-on-PDMS techniques, which enables large scale rapid prototyping of designs using minimal laboratory equipment. This technology differs from others in its use of a conductive copper paint seed layer and a unique transfer process that results in copper microstuctures embedded in PDMS. By embedding microstructures flush with PDMS surface, rather than fabricating the microstructures on the substrate surface, we produce a metallization layer that adheres to PDMS without the need for surface modifications. The fabrication process begins with the deposition of the seed layer onto a flexible substrate via airbrushing. A dry film photoresist layer is laminated on top and patterned using standard techniques. Electroplated copper is grown on the seed layer through the photoresist mask and transferred to PDMS through a unique baking procedure. This baking transfer process releases the electroplated copper from the seed layer, permanently embedding it into the cured PDMS without cracking or otherwise deforming it. We have performed initial characterizations of the copper microstructures in terms of feature size, film thickness, surface roughness, resistivity, and reliability under flexing. Initial results show that we can achieve films 25-75 micrometers in thickness, with reliable feature sizes down to 100 micrometers and a film resistivity of approximately 7.15 micro-?-cm. Process variants and future work are discussed, as well as large scale adaptations and rapid prototyping. Finally, we outline the potential uses of this technology in flexible electronics, particularly in high power applications.

Hilbich, Daniel; Khosla, Ajit; Shannon, Lesley; Gray, Bonnie L.

2014-04-01

156

A nanostructured hybrid material based on polymer infiltrated porous silicon layer  

Energy Technology Data Exchange (ETDEWEB)

In this work, we report on the fabrication of an hybrid material based on a porous silicon (PSi) layer infiltrated by an amino functionalized poly({epsilon}-caprolattone) (PCL-NH{sub 2}). The organic-inorganic structure has been characterized by variable angle spectroscopic ellipsometry, optical reflectometry and water contact angle measurements. A polymer coated PSi layer, 3 {mu}m thick, shows improved wettability and chemical stability against long lasting, up to 18 min, exposure to an alkaline environment. Even after basic treatment, the structure still retains a very good quality optical response, so that it may be proposed as a high performance platform for biochemical sensing applications. (orig.)

Stefano, L. de; Tommasi, E. de; Rea, I.; Rotiroti, L. [Inst. for Microelectronic and Microsystems, Univ. of Naples (Italy); Canciello, M.; Maglio, G.; Palumbo, R. [University of Naples, Dept. of Chemistry, Naples (Italy)

2010-03-15

157

Method of manufacturing test pieces formed with oxide layers containing radioactive materials  

International Nuclear Information System (INIS)

Purpose: To obtain test pieces having oxide layers with the same natures as oxide layers containing radioactive materials formed in high temperature and high pressure water of a nuclear reactor and also containing radioactive materials of necessary concentrations and types. Method: A solution is prepared by previously adding a predetermined amount of a solution of radioactive chloride and a solution of not-radioactive chloride of the same element to an aqueous boric acid solution controlled to a certain concentration. Then, the solution is passed through boric type anionic exchange resins to obtain a solution of radioactive boric acid salt at a required concentration not containing chlorine at all. The solution and metal pieces are put into an autoclave and, after removing the oxygen in the autoclave by nitrogen gas bubbling, heated at a required temperature for a certain period of time. Accordingly, a test specimen having oxide layers of the same natures as those containing radioactive materials formed in high temperature and high pressure water in the nuclear reactor and containing radioactive materials of required concentrations and types can be obtained. (Yoshihara, H.)

1985-05-22

158

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

159

Spin-transfer phenomena in layered magnetic structures: Physical phenomena and materials aspects  

International Nuclear Information System (INIS)

During the past 20 years, layered structures consisting of ferromagnetic layers and spacers of various material classes with a thickness of only a few nanometers have revealed a variety of exciting and potentially very useful phenomena not present in bulk material. Representing distinct manifestations of spin-transfer processes, these phenomena may be categorized into interlayer exchange coupling (IEC), giant magnetoresistance (GMR), tunneling magnetoresistance (TMR), and the more recently discovered spin-transfer torque effect leading to current-induced magnetization switching (CIMS) and current-driven magnetization dynamics. These phenomena clearly confer novel material properties on magnetic layered structures with respect to the (magneto-)transport and the magnetostatic as well as magnetodynamic behavior. Here, we will first concentrate on the less well understood aspects of IEC across insulating and semiconducting interlayers and relate the observations to TMR in the corresponding structures. In this context, we will also discuss more recent advances in TMR due to the use of electrodes made from Heusler alloys and the realization of coherent tunneling in epitaxial magnetic tunneling junctions. Finally, we will review our results on CIMS in epitaxial magnetic nanostructures showing that normal and inverse CIMS can occur simultaneously in a single nanopillar device. In all cases discussed, material issues play a major role in the detailed understanding of the spin-transfer effects, in particular in those systems that yield the largest effects and are thus of utmost interest for applications

2007-02-01

160

Hierarchical hybrid organic-inorganic materials with tunable textural properties obtained using zeolitic-layered precursor.  

Science.gov (United States)

Novel layered zeolitic organic-inorganic materials have been synthesized using a two-dimensional zeolite precursor IPC-1P prepared by a top-down approach from zeolite UTL. The formation of porous materials containing organic linkers or polyhedral oligomeric siloxane covalently bonded to zeolite layers in the interlayer space was confirmed by a variety of characterization techniques (N2/Ar sorption analysis, XRD, (29)Si and (13)C NMR, TEM). The organic-inorganic porous hybrids obtained by intercalation with silsesquioxane posessed layered morphology and contained large crystalline domains. The hybrids exhibited mesoporous or hierarchical micro-/mesoporous systems, stable up to 350 °C. Textural properties of the formed zeolitic organic-inorganic materials can be controlled by varying the linker or synthetic conditions over a broad range. Surface areas and pore volumes of synthesized hybrids significantly exceed those for parent zeolite UTL and corresponding swollen material; the amount of micropores increased with increasing rigidity and size of the organic linker in the order biphenyl > phenylene > ethanediyl. PMID:24451039

Opanasenko, Maksym; Parker, Wallace O'Neil; Shamzhy, Mariya; Montanari, Erica; Bellettato, Michela; Mazur, Michal; Millini, Roberto; ?ejka, Ji?í

2014-02-12

 
 
 
 
161

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

International Nuclear Information System (INIS)

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 ?m YIG film. - Highlights: ? A simple and original method is presented for the characterization of soft magnetic layer. ? This is a non-destructive method based on standard equipment. ? The principle is based on a comparison between simulations and measurement. ? An experimental validation is proposed as well.

2012-07-01

162

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

163

Nonlinear Localization due to a Double Negative Defect Layer in a One-Dimensional Photonic Crystal Containing Single Negative Material Layers  

International Nuclear Information System (INIS)

We investigate the effects of introducing a defect layer in a one-dimensional photonic crystal containing single negative material layers on the transmission properties. The width of the defect layer is taken to be the same or smaller than the period of the structure. Different cases of the defect layer being linear or nonlinear and double positive or double negative are discussed. It is found that only a nonlinear double negative layer gives rises to a localized mode within the zero-?eff gap in this kind of structure. It is also shown that the important characteristics of the nonlinear defect mode such as its frequency, its FWHM and the threshold of the associated bistability can be controlled by changing the widths of the defect layer and the host layers

2008-01-01

164

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

CERN Multimedia

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

Ingham, B

2004-01-01

165

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

Science.gov (United States)

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 to produce less defective, large graphene oxide nanosheets from graphite oxide in a short time (within 10?min), which show high electrical conductivity (>20,000?S m?1) of the printed film. This was achieved by adjusting the ultrasonic probe depth to the liquid surface to generate less energetic cavitation (delivered power ~6?W), while maintaining sufficient acoustic shearing (0.73?m s?1) and generating additional microbubbling by aeration at the liquid surface.

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

2014-01-01

166

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

167

Extremely efficient liquid exfoliation and dispersion of layered materials by unusual acoustic cavitation.  

Science.gov (United States)

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 to produce less defective, large graphene oxide nanosheets from graphite oxide in a short time (within 10?min), which show high electrical conductivity (>20,000?S m(-1)) of the printed film. This was achieved by adjusting the ultrasonic probe depth to the liquid surface to generate less energetic cavitation (delivered power ~6?W), while maintaining sufficient acoustic shearing (0.73?m s(-1)) and generating additional microbubbling by aeration at the liquid surface. PMID:24875584

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

2014-01-01

168

Optical fiber sensor layer embedded in smart composite material and structure  

Science.gov (United States)

A composite structure health monitoring system with optical fiber sensors is an important development in smart materials and structures. But it is difficult to embed a network of distributed optical fiber sensors in a smart composite structure, and the most effective method would be integrating the network of sensors with the polyimide film as a layer, called the optical fiber sensor layer, and then embedding the layer with optical fiber sensors in the composite material. This paper introduces three methods of making a distributed optical fiber sensor layer with polyimide. The first is to sandwich optical fiber sensors in two polyimide films. The second is to deposit the network of sensors in polyimide solution, and dry the polyimide solution. The last is to build thin-film optical waveguides and optical sensors by using fluorinated polyimide, which is expected to have high integration and high reliability. Some tests indicate that there is a little influence on the mechanical performance of the structure; however, optical fiber sensor built-in polyimide films work very well.

Pan, Xiao Wen; Liang, Da Kai; Li, Dongsheng

2006-10-01

169

Development of PZT materials, fabrication and characterization of multi layered actuators for aerospace applications  

Science.gov (United States)

Piezo Electric Materials capable of performing both "sensing" and "actuation" are known as smart materials. These materials produce electric charges on application of mechanical stress (as sensor) or undergo dimensional change when subjected to an electric field (as actuator). PZTs are preferred because of their (i) fast response time, (ii) high frequency response, (iii) precession control etc. Piezo sensors and actuators are used for various applications e.g. for vibration control of aerospace structures, development of smart aeroplane wings / morphing structures, precision flow control of propellants in space vehicles, fuel flow control in automobile engines, energy harvesting etc. At NAL, efforts are being made to prepare PZT materials, multi-layered actuators are currently fabricated and characterized for aerospace applications.

Panda, P. K.

2012-07-01

170

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

International Nuclear Information System (INIS)

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

1997-06-15

171

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

172

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.

Ou, Yiyu; Ou, Haiyan

2013-01-01

173

Pb(3)F(5)NO(3), a cationic layered material for anion-exchange.  

Science.gov (United States)

Our research involves the development of new cationic materials for anion-based applications. We report the solvothermal synthesis and characterization of Pb(3)F(5)NO(3), a new layered lead fluoride material that, unlike the majority of layered and open-framework materials, is cationic in charge. The structure consists of polyhedral lead centers connected by doubly and triply bridging fluoride groups. We quantitatively exchanged the interlamellar nitrate groups of Pb(3)F(5)NO(3) for dichromate, under ambient aqueous conditions. Nuclear magnetic resonance and UV-vis spectroscopy show the reaction proceeds to 61.0% completion in several days. The material is also stable to 450 degrees C, which is vastly superior to organic resins that are still the standard for anion-exchange. The presence of extraframework anions also opens up other potentially unique anion-based properties, such as new catalytic reactions, anion intercalation, or growth of anionic clusters within the void spaces of the cationic material. PMID:11942835

Tran, Dat T; Zavalij, Peter Y; Oliver, Scott R J

2002-04-17

174

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

International Nuclear Information System (INIS)

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

2013-07-01

175

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 <5 nm. Although the depth 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

176

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

177

Fabrication of transferable Al(2)O(3) nanosheet by atomic layer deposition for graphene FET.  

Science.gov (United States)

Without introducing defects in the monolayer of carbon lattice, the deposition of high-? dielectric material is a significant challenge because of the difficulty of high-quality oxide nucleation on graphene. Previous investigations of the deposition of high-? dielectrics on graphene have often reported significant degradation of the electrical properties of graphene. In this study, we report a new way to integrate high-? dielectrics with graphene by transferring a high-? dielectric nanosheet onto graphene. Al2O3 film was deposited on a sacrificial layer using an atomic layer deposition process and the Al2O3 nanosheet was fabricated by removing the sacrificial layer. Top-gated graphene field-effect transistors were fabricated and characterized using the Al2O3 nanosheet as a gate dielectric. The top-gated graphene was demonstrated to have a field-effect mobility up to 2200 cm(2)/(V s). This method provides a new method for high-performance graphene devices with broad potential impacts reaching from high-frequency high-speed circuits to flexible electronics. PMID:24483324

Jung, Hanearl; Park, Jusang; Oh, Il-Kwon; Choi, Taejin; Lee, Sanggeun; Hong, Juree; Lee, Taeyoon; Kim, Soo-Hyun; Kim, Hyungjun

2014-02-26

178

Radiation transport through a plasma boundary layer between armatures and material surfaces  

International Nuclear Information System (INIS)

This paper reports on the ablation of rail and insulator materials by plasma armatures which limits the velocity and the component lifetime of electromagnetic launchers. The photon radiation from the armature is the dominant form of energy transfer causing the ablation. However, not all of the escaping radiation actually is transmitted to the ablating surface and hence vapor shielding is to occur in the plasma boundary layer. A 1 D, time dependent self-consistent hydrodynamics model with a multigroup flux limited diffusion approximation for radiative transfer is used to estimate the energy transmission and the amount of ablated material. It has been found that the vapor shield is optically thin for photon energies where most of the incident source radiation is distributed, thus the simple diffusion model for radiative transfer would overestimate the radiation flux at the material surface

1991-01-01

179

Atomic layer deposition of nanostructured materials for energy and environmental applications  

Energy Technology Data Exchange (ETDEWEB)

Atomic layer deposition (ALD) is a thin film technology that in the past two decades rapidly developed from a niche technology to an established method. It proved to be a key technology for the surface modification and the fabrication of complex nanostructured materials. In this Progress Report, after a short introduction to ALD and its chemistry, the versatility of the technique for the fabrication of novel functional materials will be discussed. Selected examples, focused on its use for the engineering of nanostructures targeting applications in energy conversion and storage, and on environmental issues, will be discussed. Finally, the challenges that ALD is now facing in terms of materials fabrication and processing will be also tackled. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Marichy, Catherine [Department of Chemistry, CICECO, University of Aveiro (Portugal); Bechelany, Mikhael [Institut Europeen des Membranes (ENSCM, UMR CNRS 5635), Universite Montpellier 2, Montpellier (France); Pinna, Nicola [Department of Chemistry, CICECO, University of Aveiro (Portugal); World Class University (WCU) Program of Chemical, Convergence for Energy and Environment (C2E2), School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul (Korea, Republic of)

2012-02-21

180

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

 
 
 
 
181

Preparation of thin layer materials with macroporous microstructure for SOFC applications  

International Nuclear Information System (INIS)

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

2008-04-01

182

Embedded proteins and sacrificial bonds provide the strong adhesive properties of gastroliths  

DEFF Research Database (Denmark)

The adhesive properties of gastroliths from a freshwater crayfish (Cherax quadricarinatus) were quantified by colloidal probe atomic force microscopy (AFM) between heavily demineralized gastrolith microparticles and gastrolith substrates of different composition. Combined AFM and transmission electron microscopy studies demonstrated that the sequential detachment and large adhesion energies that characterise the adhesive behaviour of a native gastrolith substrate are dominated by sacrificial bonds between chitin fibres and between chitin fibres and CaCO3. The sacrificial bonds were shown to be strongly related to the gastrolith proteins and when the majority of these proteins were removed by ethylenediaminetetraacetic acid (EDTA), the sequential detachment disappeared and the adhesive energy was reduced by more than two orders of magnitude. © 2012 The Royal Society of Chemistry.

Thormann, Esben; Mizuno, Hiroyasu

2012-01-01

183

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

Science.gov (United States)

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

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

2013-03-01

184

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

Science.gov (United States)

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

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

2014-03-01

185

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

Energy Technology Data Exchange (ETDEWEB)

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 CeO{sub 2}-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.

Filatov, Oleksandr Y. [Taras Shevchenko Kyiv University, Department of Physics, 6 Av. Acad Glushkov, Kyiv 22 (Ukraine); Poperenko, Leonid V. [Taras Shevchenko Kyiv University, Department of Physics, 6 Av. Acad Glushkov, Kyiv 22 (Ukraine)]. E-mail: plv@phys.univ.kiev.ua

2006-10-31

186

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)

2007-03-01

187

Phase-change material for use in rewritable dual-layer optical disk  

Science.gov (United States)

A thin film of Sn-doped and GeTe-rich GeTe-Sb2Te3 shows characteristics that make it suitable for use in rewritable dual-layer optical disks employing a violet laser. By increasing the GeTe component form Ge2Sb2Te5 to Ge4Sb2Te7, and Ge8Sb2Te11, optical changes were increased. By substituting Sn for a proposition of Ge in these compositions, crystallization rates are greatly increased and even a 5 nm-thick film showed a very short laser-crystallization time of less than 50 ns. The material film was successfully applied to Layer 0 of rewritable dual-layer disk: capacity of 27 GB and a 33 Mbps data transfer rate were confirmed for a disk using a conventional 0.6 mm substrate, and 45 GB capacity and the same data transfer rate were obtained for another disk using thin cover layer 0.1 mm thick.

Yamada, Noboru; Kojima, Rie; Uno, Mayumi; Akiyama, Tetsuya; Kitaura, Hideki; Narumi, Kenji; Nishiuchi, Kenichi

2002-01-01

188

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 p...

Rinco?n, O.; Sa?nchez, M.; Romero, M.; Paz, G.; Campos, W.

2003-01-01

189

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

190

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

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

191

Improving the efficiency of organic solar cells by varying the material concentration in the photoactive layer  

Science.gov (United States)

Polymer-fullerene bulk heterojunction solar cells have been a rapidly improving technology over the past decade. To further improve the relatively low energy conversion efficiencies of these solar cells, several modifications need to be made to the overall device structure. Emerging technologies include cells that are fabricated with interfacial layers to facilitate charge transport, and tandem structures are being introduced to harness the absorption spectrum of polymers with varying bandgap energies. When new structures are implemented, each layer of the cell must be optimized in order for the entire device to function efficiently. The most volatile layer of these devices is the photoactive layer solution of poly-3(hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC 61BM). Even slight variations in pre-application and post-treatment will lead to large variations in the electrical, physical, and optical properties of the solar cell module. To improve the effectiveness of the photoactive layer, the material concentration of P3HT and PC61BM in the liquid phase, prior to application, was altered. The weight ratio of P3HT to PC61BM was kept at a constant 1 to 0.8, while the amounts of each dissolved in 2 mL of chlorobenzene were varied. Solar cells were fabricated, and J-V characterizations were performed to determine the electrical traits of the devices. Atomic force microscopy (AFM) measurements were done on the photoactive layer films to determine the physical characteristics of the films such as overall surface topology and RMS roughness. Also, variable angle spectroscopic ellipsometry (VASE) was used to determine film thickness and extinction coefficient of the active layers. To further understand the optical properties of the polymer-fullerene blend, the absorption spectrum of the films were calculated through UV-VIS spectrophotometry. It was found that an increased concentration of the polymer-fullerene blend prior to application increased overall device efficiency. A photoactive layer solution prepared with 30 mg P3HT and 24 mg PC61BM, when implemented in an organic solar cell, produced the optimal electrical, physical, and optical characteristics.

Latimer, Kevin Anthony

192

Materials | Free Full-Text | Graphene as a Buffer Layer for Silicon Carbide-on-Insulator Structures  

...Graphene as a Buffer Layer for Silicon Carbide-on-Insulator Structures We report an innovative technique for growing the silicon carbide-on-insulator (SiCOI) structure by ... Graphene as a Buffer Layer for Silicon Carbide-on-Insulator Structures We report an innovative technique for growing the silicon carbide-on-insulator (SiCOI) structure ... silicon carbide Graphene as a Buffer Layer for Silicon Carbide-on-Insulator Structures Materials | Free Full-Text | Graphene as a Buffer Layer ...for Silicon Carbide-on-Insulator Structures Submit to Materials Login Register MDPI Journals A-Z For Authors For Editors For Librarians About Open Access Policy Title /...

193

Emanation thermal analysis for characterization of surface and near surface layers of advanced materials  

International Nuclear Information System (INIS)

A non traditional method, called emanation thermal analysis (ETA), was used the for characterization of surface and near surface layers of SiC based materials. This method consists in the measurement of the release of inert gas (radon) from the samples previously labeled to the depth of several tens of nanometers with the inert gas atoms. The ETA results brought about information about microstructure changes and transport properties of SiC/SiC_f composites on heating in the range 30-1300degC in argon and air, respectively. The annealing of structure irregularities which served as diffusion paths for radon was evaluated. The temperature range of the formation and crystallization of the silica layer resulting after oxidation of the SiC/SiC_f sample on heating in air was determined from the ETA results. (author)

2003-03-01

194

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.

2010-09-01

195

Photocatalytic production of hydrogen from electrodeposited p-Cu{sub 2}O film and sacrificial electron donors  

Energy Technology Data Exchange (ETDEWEB)

A new approach to combining a p-type semiconductor photocathode with sacrificial electron donors in the anode compartment in a two-compartment cell is described for photocatalytic hydrogen production. This approach is demonstrated for electrodeposited p-Cu{sub 2}O film supported on a transparent conducting oxide substrate. The oxide semiconductor surface was photochemically modified in situ with an ultra-thin Ni layer prior to use. A variety of organic and organometallic electron donors was screened by cyclic voltammetry, and the optimal candidate was hydroquinone at pH 10. Importantly, no photocurrents were measured at zero bias voltage in the two-compartment cell in the absence of an electron donor, signaling that water photosplitting is not feasible with p-Cu{sub 2}O. Methyl viologen (MV{sup 2+}) was effective as an electron relay in the photocathode chamber as shown by in situ spectroscopic monitoring of the MV{sup +} radical cations. Finally, practical perspectives of this new approach and value-added options for combining it with pollutant destruction are described. (author)

Somasundaram, Sashikala; Raman Nair Chenthamarakshan, C.; Tacconi, Norma R. de; Rajeshwar, Krishnan [Center for Renewable Energy Science and Technology (CREST), Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019-0065 (United States)

2007-12-15

196

Polymer-layered silicate nanocomposite materials: Morphological studies and potential applications  

Science.gov (United States)

Polymer-layered silicate nanocomposites, materials where layered silicates are molecularly dispersed in suitable polymer matrices, are of both scientific and commercial significance. The dramatic enhancements in tensile strength, heat and solvent resistance, as well as the decrease in gas permeability of the neat polymer matrix that can be achieved through the incorporation of small amounts of a suitable layered silicate are intricately linked to the nanocomposite morphology. In the current work, the morphological behavior of nanocomposite materials has been investigated by the fabrication and extensive characterization of a series of model experimental systems. The results from the experimental systems that were developed based on one of the theoretical models for morphology prediction in nanocomposites, provide useful insight into controlling nanocomposite morphology by tailoring various system parameters. The unique properties of nanocomposites also make them promising materials for use as electrolytes in lithium polymer batteries. Though an all-solid-state lithium polymer battery is attractive due to characteristics such as low safety risks in comparison with the conventional systems that contain liquid electrolytes, several challenges related to materials design have to be overcome in order to create materials that have good mechanical properties. Our work focuses on the development of a new class of nanocomposite electrolytes where the incorporation of lithium cation-exchanged nanoscale clay sheets into a suitable polymer matrix is expected to impart the inherent favorable characteristics of nanocomposites to the electrolyte. Additionally, this modification is expected to substantially eliminate the need for lithium salt dopants that are currently used to achieve significant conductivities and form what are essentially single-ion conductors. Extensive characterization of these electrolytes showed that properties were strongly dependent on nanocomposite morphology. Results for the strategies developed for controlling morphology and hence electrolyte properties, through the use of appropriate organic silicate modifying are also reported. The current body of work provides an insight into the underlying factors that influence nanocomposite morphology and also provides guidelines to control morphology through the intelligent design of components and choice of system parameters. Suggestions are made for future work that would further the understanding of these complex hybrid materials and extend their applications.

Kurian, Mary

197

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

International Nuclear Information System (INIS)

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

1995-07-09

198

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.

2009-03-22

199

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

2007-01-01

200

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

Science.gov (United States)

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

Scott, Isaac David

 
 
 
 
201

Sputtered platinum-iridium layers as electrode material for functional electrostimulation  

International Nuclear Information System (INIS)

In this study co-sputtered layers of platinum-iridium (PtIr) are investigated as stimulation electrode material. The effects of different sputter parameters on the morphology and the electrochemical behavior are examined. It is shown that films sputtered at the lowest incident energy possess the highest charge storage capacity (CSC). At a Pt:Ir atomic-ratio of 55:45 the obtained CSC of 22 mC/cm2 is enhanced compared to the standard stimulation material platinum (16 mC/cm2) but inferior to iridium which has a CSC of 35 mC/cm2. Long term cyclic voltammetry measurements show that PtIr can be activated which increases the CSC to 29 mC/cm2. Also a change in the film morphology is observed. Sputtered platinum-iridium films promise to combine high mechanical strength and increased charge storage capacity.

2011-03-31

202

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

203

Charge trap flash memory using ferroelectric materials as a blocking layer  

Science.gov (United States)

In this paper, we propose a charge-trap flash memory device using a ferroelectric material, Sr0.7Bi2.3Nb2O9 (SBN), with spontaneous polarization as a blocking layer. This device consists of metal/SBN/nitride/oxide/silicon and has an advantage in the carrier injection into the nitride from the silicon due to polarization charges formed in the ferroelectric material. Compared to conventional metal/oxide/nitride/oxide/silicon memory devices, the proposed devices showed a larger memory window (7 V), faster program/erase (P/E) speeds (100/500 ?s), and higher endurance (105 P/E cycles) with comparable retention properties.

Seo, Yujeong; An, Ho-Myoung; Yeong Song, Min; Geun Kim, Tae

2012-04-01

204

Investigation of epitaxial silicon layers as a material for radiation hardened silicon detectors  

Energy Technology Data Exchange (ETDEWEB)

Epitaxial grown thick layers (>100 {mu}m) of high resistivity silicon (Epi-Si) have been investigated as a possible candidate of radiation hardened material for detectors for high-energy physics. As grown Epi-Si layers contain high concentration (up to 2{center_dot}10{sup 12} cm{sup {minus}3}) of deep levels compared with that in standard high resistivity bulk Si. After irradiation of test diodes by protons (E{sub p} = 24 GeV) with a fluence of 1.5{center_dot}10{sup 11} cm{sup {minus}2}, no additional radiation induced deep traps have been detected. A reasonable explanation is that there is a sink of primary radiation induced defects, in epitaxial layers. The {open_quotes}sinking{close_quotes} process, however, becomes non-effective at high radiation fluences (10{sup 14} cm{sup {minus}2}) due to saturation of epitaxial defects by high concentration of radiation induced ones. As a result, at neutron fluence of 1{center_dot}10{sup 14}cm{sup {minus}2} the deep level spectrum corresponds to well-known spectrum of radiation induced defects in high resistivity bulk Si. The net effective concentration in the space charge region equals to 3{center_dot}10{sup 12} cm{sup {minus}3} after 3 months of room temperature storage and reveals similar annealing behavior for epitaxial as compared to bulk silicon.

Li, Z. [Brookhaven National Lab., Upton, NY (United States); Eremin, V.; Ilyashenko, I.; Ivanov, A. [Russian Academy of Sciences, St-Petersburg (Russian Federation). Ioffe Physico-Technical Institute] [and others

1997-11-01

205

Investigation of epitaxial silicon layers as a material for radiation hardened silicon detectors  

Energy Technology Data Exchange (ETDEWEB)

Epitaxial grown thick layers ({ge} 100 micrometers) of high resistivity silicon (Epi-Si) have been investigated as a possible candidate of radiation hardened material for detectors for high-energy physics. As grown Epi-Si layers contain high concentration (up to 2 {times} 10{sup 12} cm{sup {minus}3}) of deep levels compared with that in standard high resistivity bulk Si. After irradiation of test diodes by protons (E{sub p} = 24 GeV) with a fluence of 1.5 {times} 10{sup 11} cm{sup {minus}2}, no additional radiation induced deep traps have been detected. A reasonable explanation is that there is a sink of primary radiation induced defects (interstitial and vacancies), possibly by as-grown defects, in epitaxial layers. The ``sinking`` process, however, becomes non-effective at high radiation fluences (10{sup 14} cm{sup {minus}2}) due to saturation of epitaxial defects by high concentration of radiation induced ones. As a result, at neutron fluence of 1 {times} 10{sup 14} cm{sup {minus}2} the deep level spectrum corresponds to well-known spectrum of radiation induced defects in high resistivity bulk Si. The net effective concentration in the space charge region equals to 3 {times} 10{sup 12} cm{sup {minus}3} after 3 months of room temperature storage and reveals similar annealing behavior for epitaxial as compared to bulk silicon.

Li, Z. [Brookhaven National Lab., Upton, NY (United States); Eremin, V.; Ilyashenko, I.; Ivanov, A.; Verbitskaya, E. [Russian Academy of Sciences, St. Petersburg (Russian Federation). Ioffe Physico-Technical Inst.; CERN RD-48 ROSE Collaboration

1997-12-01

206

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

International Nuclear Information System (INIS)

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

2004-04-28

207

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

International Nuclear Information System (INIS)

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

2010-01-01

208

Study on coated layer material performance of coated particle fuel FBR (2). High temperature property and capability of coating to thick layer of TiN  

International Nuclear Information System (INIS)

'Helium Gas Cooled Coated Particle Fuel FBR' is one of attractive core concepts in the Feasibility Study on Commercialized Fast Reactor Cycle System in Japan, and the design study is presently proceeded. As one of key technologies of this concept, the coated layer material is important, and ceramics is considered to be a candidate material because of the superior refractory. Based on existing knowledge, TiN is regarded to be a possible candidate material, to which some property tests and evaluations have been conducted. In this study, preliminary tests about the high temperature property and the capability of thick layer coating of TiN have been conducted. Results of these tests come to the following conclusions. Heating tests of two kinds of TiN layer specimens coated by PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition) were conducted. As a result, as for CVD coating specimens, remarkable charge was not observed on the layer up to 2,000degC, therefore we concluded that the layer by CVD had applicability up to high temperature of actual operation level. On the other hand, as for PVD coating specimens, an unstable behavior that the layer changed to a mesh like texture was observed on a 2,000degC heated specimen, therefore the applied PVD method is not considered to be promising as the coating technique. The surface conditions of some parts inside CVD device were investigated in order to evaluate possibility of TiN thick coating (?100 ?m). As a result, around 500 ?m of TiN coating layer was observed on the condition of multilayer. Therefore, we conclude that CVD has capability of coating up to thick layer in actual coated particle fuel fabrication. (author)

2002-01-01

209

V(z) curves of layered anisotropic materials for the line-focus acoustic microscope  

Energy Technology Data Exchange (ETDEWEB)

V(z) curves for a line-focus acoustic microscope have been calculated in terms of the characteristic functions of the acoustic lens and the reflectance function of the fluid-loaded specimen. More accurate expressions for the characteristic functions of the acoustic lens are presented by taking account of attenuation in the coupling fluid, the angular dependence of transmission by the antireflection coating on the lens surface, and by making a better estimate of the focal length. The reflectance function has been calculated for anisotropic layers deposited on anisotropic substrates. The calculated V(z) curves have been compared with measurements for isotropic and anisotropic materials, and layered anisotropic materials. The surface acoustic wave velocities obtained from the theoretical and the measured V(z) curves have been compared for the full range of directions of wave propagation. The comparisons of V(z) curves and surface acoustic wave velocities show excellent agreement between theoretical and experimental results. 21 refs., 11 figs., 2 tab.

Lee, Y.C.; Kim, J.O.; Achenbach, J.D. (Northwestern Univ., Evanston, IL (United States))

1993-08-01

210

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

211

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

Science.gov (United States)

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

Heide, Bernd

2013-10-01

212

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-02-15

213

Alternative material to mitigate chrome degradation on high volume ArF layers  

Science.gov (United States)

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

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

2013-09-01

214

Study on coated layer material characteristics of coated particle fuel FBR (3). Thick layer coating processes of TiN and gas-nitriding treatment of Ti metal  

International Nuclear Information System (INIS)

'Helium gas cooled FBR' is one of attractive core concepts, so that the design studies have been performed in the Feasibility Study on Commercialized Fast Reactor Cycle System in Japan. Authors consider the coated particle fuelling core is promising as the helium gas cooled FBR core, thus studies of the core are advanced. One of the key points of the coated particle fuel is the coated layer material, for whom ceramics is considered as a candidate because of the superior refractory. Existing knowledge shows that TiN is one of possible materials, therefore, authors have conducted tests and evaluations to reveal characteristics of TiN layer. In this study, tests about TiN coating methods and gaseous nitriding of Ti metal to obtain thick layer were conducted. (author)

2006-01-01

215

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

Science.gov (United States)

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

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

2013-08-01

216

Synthesis and Properties of Layered Organic-inorganic Hybrid Material: Zn-Al Layered Double Hydroxide-dioctyl Sulfosuccinate Nanocomposite  

Energy Technology Data Exchange (ETDEWEB)

A layered organic-inorganic hybrid nanocomposite was prepared by using a surfactant, dioctyl sulphosuccinate (DSS) as a guest in Zn-Al layered double hydroxide (LDH) inorganic host by a self-assembly technique. The Zn-Al ratio of the mother liquor was kept constant at 4 at the beginning of the synthesis. Powder X-ray diffractogram shows that the basal spacing of the Zn-Al LDH with sulphate as the intergallery anion (ZASUL) expanded from 11.0 to 26.3 A to accommodate the DSS surfactant anion for the formation of the Zn-Al LDH-DSS layered organic-inorganic hybrid nanocomposite (ZADON). It was also found that the BET surface area reduced by about 90%, from 22.5 to 2.2 m{sup 2}/g, for ZASUL and ZADON, respectively if 0.1 M DSS was used for the synthesis of the latter.

Mohd Zobir bin Hussein, E-mail: mzobir@sfsas.upm.edu.my; Tan Kim Hwa [Universiti Putra Malaysia, Multifunctional Materials for Industrial Application (MULIA) Research Group, Department of Chemistry (Malaysia)], E-mail: mzobir@sfsas.upm.edu.my

2000-09-15

217

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 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

2007-07-01

218

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

Science.gov (United States)

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.; Puértolas, J. A.; Pascual, F. J.; Hernández-Ferrer, J.; Castell, P.; Benito, A. M.; Maser, W. K.; Martínez, M. T.

2014-05-01

219

Biofabrication of multi-material anatomically shaped tissue constructs.  

Science.gov (United States)

Additive manufacturing in the field of regenerative medicine aims to fabricate organized tissue-equivalents. However, the control over shape and composition of biofabricated constructs is still a challenge and needs to be improved. The current research aims to improve shape, by converging a number of biocompatible, quality construction materials into a single three-dimensional fiber deposition process. To demonstrate this, several models of complex anatomically shaped constructs were fabricated by combined deposition of poly(vinyl alcohol), poly(?-caprolactone), gelatin methacrylamide/gellan gum and alginate hydrogel. Sacrificial components were co-deposited as temporary support for overhang geometries and were removed after fabrication by immersion in aqueous solutions. Embedding of chondrocytes in the gelatin methacrylamide/gellan component demonstrated that the fabrication and the sacrificing procedure did not affect cell viability. Further, it was shown that anatomically shaped constructs can be successfully fabricated, yielding advanced porous thermoplastic polymer scaffolds, layered porous hydrogel constructs, as well as reinforced cell-laden hydrogel structures. In conclusion, anatomically shaped tissue constructs of clinically relevant sizes can be generated when employing multiple building and sacrificial materials in a single biofabrication session. The current techniques offer improved control over both internal and external construct architecture underscoring its potential to generate customized implants for human tissue regeneration. PMID:23817739

Visser, Jetze; Peters, Benjamin; Burger, Thijs J; Boomstra, Jelle; Dhert, Wouter J A; Melchels, Ferry P W; Malda, Jos

2013-09-01

220

Biofabrication of multi-material anatomically shaped tissue constructs  

International Nuclear Information System (INIS)

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

2013-09-01

 
 
 
 
221

Zinc oxide grown by atomic layer deposition - a material for novel 3D electronics  

Energy Technology Data Exchange (ETDEWEB)

Last years we observe a booming interest in materials which can be successfully grown at low temperature limits showing good structural and electrical characteristics. This trend is closely related to the novel three-dimensional (3D) architecture which seems to be a prospective solution for miniaturization of electronic devices after the 22 nm node. We demonstrate that electrical parameters of ZnO grown by the atomic layer deposition (ALD) method at low temperature limit (100-200 C) fulfil requirements for 3D electronic devices, because electron carrier mobility is above 10 cm{sup 2}/Vs and n concentration at the level of 1 x 10{sup 17} cm{sup -3}. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Guziewicz, Elzbieta; Krajewski, Tomasz A.; Wachnicki, Lukasz; Luka, Grzegorz; Domagala, Jaroslaw Z.; Paszkowicz, Wojciech; Kowalski, Bogdan J.; Witkowski, Bartlomiej S.; Suchocki, Andrzej [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Godlewski, Marek [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Department of Mathematics and Natural Sciences, College of Science Cardinal Stefan Wyszynski University, Warsaw (Poland); Duzynska, Anna [Department of Mathematics and Natural Sciences, College of Science Cardinal Stefan Wyszynski University, Warsaw (Poland)

2010-07-15

222

Non-destructive characterization of surface layers on non ferromagnetic materials  

International Nuclear Information System (INIS)

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

1997-10-27

223

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

Energy Technology Data Exchange (ETDEWEB)

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 ZrS{sub x}Se{sub 2-x} where 0{<=}x{<=}2, HfSe{sub 2}, HfS{sub 2}, TiTe{sub 2}, NbTe{sub 2}, TaS{sub 2}) 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.

Moustafa, Mohamed; Paulheim, Alexander; Niehle, Michael; Mildner-Spindler, Karl; Janowitz, Christoph; Manzke, Recardo [Institut fuer Physik, Humboldt-Universitaet zu Berlin (Germany)

2009-07-01

224

Metal sputtering and hydrogen retention in metal-carbon composite layer materials  

Energy Technology Data Exchange (ETDEWEB)

The sputtering of metal atoms and the retention and release of hydrogen isotopes in metal-carbon composite layer materials are discussed. The criteria for suppression of metal sputtering are derived on the basis of the concentration of carbon atoms segregated at the surface, which is calculated taking into account segregation and dissolution at the surface and at the interface as well as diffusion. Data on the ion flux dependence of the sputtering yield of metal from different metal-carbon systems are presented, and the critical flux and thicknesses required for suppression of metal sputtering are discussed. Furthermore, data on retention and release of implanted hydrogen isotopes are presented and compared with those for graphite.

Morita, K. (Nagoya Univ., Faculty of Engineering, Dept. of Crystalline Materials Science, Furo-cho, Chikusa-ku, Nagoya 464-01 (JP))

1991-07-01

225

Photon tunneling and transmittance resonance through a multi-layer structure with a left-handed material  

International Nuclear Information System (INIS)

This paper investigates the photon tunneling and transmittance resonance through a multi-layer structure including a left-handed material(LHM). An analytical expression for the transmittance in a five-layer structure is given by the analytical transfer matrix method. The transmittance is studied as a function of the refractive index and the width of the LHM layer. The perfect photon tunneling results from the multi-layer structure, especially from the relation between the magnitude of the refractive index and the width of the LHM layer and those of the adjoining layers. Photons may tunnel through a much greater distance in this structure. Transmittance resonance happens, the peaks and valleys appear periodically at the resonance thickness. For an LHM with inherent losses, the perfect transmittance is suppressed. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

2011-05-01

226

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

Science.gov (United States)

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.

Xiang, H. J.; Shi, Z. F.; Wang, S. J.; Mo, Y. L.

2012-11-01

227

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)

2012-11-01

228

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

229

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

230

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

International Nuclear Information System (INIS)

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

2013-01-15

231

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

Science.gov (United States)

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

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

2011-06-01

232

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

233

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

DEFF Research Database (Denmark)

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

Johnsen, Rune E.; Christiansen, Ane Sælland

2014-01-01

234

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

International Nuclear Information System (INIS)

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

2007-06-01

235

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

236

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

237

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

238

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

239

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

2013-12-01

240

Synthesis, characterization, and application of novel microporous mixed metal oxides, and nanostructured layered material-polymer films  

Science.gov (United States)

Zeolites are microporous crystalline aluminosilicates with pores and cavities of molecular dimension. They consist of interconnected aluminum and silicon tetrahedra to build a variety of 3D open framework structures. Due to their structure, stability, and activity, zeolites have been widely used in a broad variety of applications in industry. It is, therefore, of great interest to make new structures with potentially novel properties. In this regard, there has recently been a growing interest in the synthesis of novel mixed metal oxides with octahedral and tetrahedral units owing to the possibility to find unique electronic and optical properties. Hence, these materials can find advanced applications as well as conventional applications, just like zeolites. Research efforts have led to the discovery of several mixed octahedral and tetrahedral metal oxides with novel crystal structures including titanium silicates and cerium silicate. Layered materials with transport paths along the thickness of the layers are of particular interest due to potential usage as selective layers of nanometer scale in nanocomposite membranes. A new layered silicate (we call AMH-3) has been synthesized under hydrothermal conditions. The crystal structure solution via powder X-ray diffraction has revealed its unique layer structure of three dimensional microporosity within layers. Layered materials with porous layers will open up new areas of applications, such as selective nanocomposite separation membranes. Polymer/selective-flake nanocomposite membranes have been fabricated for the first time, which can, in principle, be scaled down to submicrometer structures. A layered aluminophosphate with a porous net layer is used as a selective phase and a polyimide as a continuous phase. The microstructures of the nanocomposite membranes were investigated using various characterization techniques. Nanocomposite membranes with 10 wt% layered aluminophosphate show substantial enhancement in performance with oxygen selectivity over nitrogen as high as 8.9 (as compared to 3.6 of pure polymer) and carbon dioxide selectivity over methane as high as 40.9 (as compared to 13.4 of pure polymer) in room temperature permeation measurements. This improved performance, along with permeability estimation through the aluminophosphate layers with a semiempirical model, suggests that the layered aluminophosphate acts as a molecular sieve favoring smaller molecules.

Jeong, Hae-Kwon

 
 
 
 
241

Laser induced forward transfer aluminum layers: Process investigation by time resolved imaging  

International Nuclear Information System (INIS)

Highlights: ? Side- and front-on shadowgraphy. ? Aluminum flyer is ejected intact for all tested energies. ? Indications of bending of the aluminum flyer are shown. - Abstract: Laser induced forward transfer of an aluminum thin film on a triazene polymer as a sacrificial layer has been studied with time resolved imaging. Both side- and front-on imaging of the process give a more detailed understanding of the stability of the ejected material during flight. For high fluence ablation (800 mJ/cm2) the flyer is stable for 400 ns and gets decomposed completely when interacting with the shockwave after 1 ?s. Material detachments on the edges of the flyer are observed at an early stage of the ablation process (2) the flyer has the size of the ablation spot and keeps its shape for nearly 1 ?s. The back pressure of the decomposed triazene polymer bends the flyer towards the direction of flight and indications for folding are observed.

2012-09-15

242

Self-organized cobalt fluoride nanochannel layers used as a pseudocapacitor material.  

Science.gov (United States)

Aligned CoF2 nanochannel layers have been formed by self-ordering electrochemical anodization. In voltammograms these layers provide multiple oxidation states, an almost ideal rectangular pseudocapacitive behavior, a high specific capacitance and good capacitance retention. These layers may thus be promising for supercapacitor applications. PMID:24848598

Lee, Chong-Yong; Su, Zixue; Lee, Kiyoung; Tsuchiya, Hiroaki; Schmuki, Patrik

2014-07-01

243

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

244

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

245

Optimizing the design of bio-inspired functionally graded material (FGM) layer in all-ceramic dental restorations.  

Science.gov (United States)

Due to elastic modulus mismatch between the different layers in all-ceramic dental restorations, high tensile stress concentrates at the interface between the ceramic core and cement. In natural tooth structure, stress concentration is reduced by the functionally graded structure of dentin-enamel junction (DEJ) which interconnects enamel and dentin. Inspired by DEJ, the aim of this study was to explore the optimum design of a bio-inspired functionally graded material (FGM) layer in all-ceramic dental restorations to achieve excellent stress reduction and distribution. Three-dimensional finite element model of a multi-layer structure was developed, which comprised bilayered ceramic, bio-inspired FGM layer, cement, and dentin. Finite element method and first-order optimization technique were used to realize the optimal bio-inspired FGM layer design. The bio-inspired FGM layer significantly reduced stress concentration at the interface between the crown and cement, and stresses were evenly distributed in FGM layer. With the optimal design, an elastic modulus distribution similar to that in DEJ occurred in the FGM layer. PMID:24583648

Cui, Chang; Sun, Jian

2014-01-01

246

Pressure-induced transformations of AgIIF2-towards an 'infinite layer' d9 material  

International Nuclear Information System (INIS)

The enthalpy of seven polymorphs of AgF2 has been scrutinized up to 50 GPa using density functional theory (DFT) calculations. We show that ?-AgIIF2 (Pbca, with its puckered-sheet structure and an elongated octahedral 4+2 coordination of Ag) transforms above 15 GPa into a layered polymorph ? (Abma). The Jahn-Teller effect persists and the coordination of Ag(II) is of the 4+4 type; the Ag-F-Ag bridges are bent. Cubic ? structure of the CaF2 type (Fm-bar3m), and its Pa3 variant (?), rutile (?), and tetragonal 'infinite chain' P4mm structure related to AgFBF4 (?) are not preferred in the entire pressure window that was investigated. Electronic structure of high-pressure ?-AgIIF2 form shows features that are characteristic for two-dimensional (2D) materials, a prerequisite for high-TC superconductivity. Our calculations also suggest that experimentally observed high-temperature ?-AgF2 (Imcm, disproportionated, i.e. a charge-density-wave form, AgIAgIIIF4) is indeed metastable; it is slightly endothermic compared to ?-AgIIF2

2007-03-21

247

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

248

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

249

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

250

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).

2012-06-15

251

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

International Nuclear Information System (INIS)

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

2006-10-25

252

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

253

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.

2009-05-29

254

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

Energy Technology Data Exchange (ETDEWEB)

Pyromellitic dianhydride (PMDA) and trimellitic anhydride (TMA) were tried as cathode interfacial layers between tris-(8-hydroxyquinoline) aluminum (Alq{sub 3}) 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.

Nam, Eunkyoung [Department of Physics, Brain Korea 21 Physics Research Division, Institute of Basic Science, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Park, Hyungjun [School of Information and Communication Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Park, Keunhee; Moon, Mi Ran [Department of Physics, Brain Korea 21 Physics Research Division, Institute of Basic Science, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Sohn, Sunyoung [Korea Basic Science Institute, Dukjin Dong 664-14, Jeonju 561-756 (Korea, Republic of); Jung, Donggeun [Department of Physics, Brain Korea 21 Physics Research Division, Institute of Basic Science, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Yi, Junsin [School of Information and Communication Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Chae, Heeyeop [Department of Chemical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Kim, Hyoungsub, E-mail: hsubkim@skku.ed [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of)

2009-05-29

255

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

Science.gov (United States)

A polymeric percutaneous device with good biocompatibility and resistance to bacterial infection is required clinically. In this study, a fibroblast growth factor-2 (FGF-2)-hydroxyapatite (HAp) composite layer (FHAp layer) was formed on the surfaces of ethylene-vinyl alcohol copolymer (EVOH) specimens using a coating process in a supersaturated calcium phosphate solution supplemented with FGF-2. FGF-2 in the FHAp layer retained its biological activity to promote proliferation of fibroblasts. The EVOH specimens coated with HAp and FHAp layers were percutaneously implanted in the scalp of rats. Not only the HAp layer but also the FHAp layer showed good biocompatibility, and FGF-2 showed no harmful effects on the skin tissue responses to the implanted specimen as long as 14 d. No significantly higher infection resistance was verified for the FHAp layer over the HAp layer, although an FHAp layer coated on a metallic percutaneous device for bone fixation demonstrated higher resistance to bacterial infection over an HAp layer in the previous study. The efficacy of FHAp layers coated on percutaneous implants in resistance to bacterial infection depends on physical factors including fixation condition, stiffness and movement of implants. PMID:20966534

Sasaki, Kenkichi; Oyane, Ayako; Hyodo, Koji; Ito, Atsuo; Sogo, Yu; Kamitakahara, Masanobu; Ioku, Koji

2010-12-01

256

Thermal stress in a bi-material assembly with a 'piecewise-continuous' bonding layer: theorem of three axial forces  

International Nuclear Information System (INIS)

We consider a bi-material assembly with a 'piecewise-continuous' bonding layer. The layer is characterized by different elastic constants of its 'pieces' (segments) and is assumed to be thin. Young's moduli of all the 'pieces' of the bonding layer are significantly lower than the moduli of the adherend materials. In such a situation the coefficient of thermal expansion (CTE) of the bonding material need not be accounted for. Only the interfacial compliance of the bonding layer is important. This is indeed the case for the majority of electronic, opto-electronic or photonic assemblies. We consider the situation when the assembly is manufactured at an elevated temperature and is subsequently cooled down to a low (say, room) temperature. The objective of the analysis is to develop a simple, easy-to-use and physically meaningful analytical ('mathematical') predictive model for the evaluation of the interfacial shearing stresses that arise at the boundaries of the 'pieces' (segments) of the bonding layer and at the assembly edge. The basic equation is obtained for the thermally induced forces acting in the adherends' cross-sections that correspond to the boundaries between the dissimilar portions of the bonding layer. This equation has the form of the theorem of three (bending) moments in the theory of multi-span beams lying on separate simple supports and could therefore be called the 'theorem of three axial forces'. We show, as an illustration, how this equation could be employed to design a bi-material assembly with an inhomogeneous bonding layer and with low interfacial shearing stresses. Low shearing stresses will certainly result in lower peeling stresses as well. The numerical example is carried out for an assembly with a relatively high-modulus bonding material in its mid-portion (aimed primarily at providing good adhesion and, if necessary, good heat transfer as well) and a low-modulus material in its peripheral portions (aimed primarily at bringing down the interfacial stresses). The maximum interfacial shearing stress in the assembly with the inhomogeneous bonding layer turned out to be only about 30% of the maximum shearing stress in an assembly with a homogeneous bonding layer having throughout its length the same modulus as the bonding material in the mid-portion of an assembly with an inhomogeneous bond. We would like to emphasize that the inhomogeneous bonding material addressed in this analysis does not necessarily have to be an epoxy one. Many other bonding materials with different moduli in the mid-portion and at the peripheral portions of the assembly could be considered for various practical applications. For instance, a high-modulus solder material such as, say, a tin-silver-copper (SAC) solder can be employed in the mid-portion of an assembly and a low-modulus solder (e.g. an indium-based alloy) at its peripheral portions. In other applications a high-modulus solder material could be considered for the mid-portion of the assembly and a low-modulus epoxy adhesive at its peripheral portions. We would also like to point out that the developed concept can be easily generalized for the situations when the bonding material is not a continuous one, but is of the ball-grid-array (BGA) or a pad-grid-array (PGA) type. Our concept could also be easily generalized for a two-dimensional case, for the situation when bending deformations should be accounted for, for non-uniform distribution of temperature (i.e. for assemblies with temperature gradients in the through-thickness and/or in the longitudinal direction), for situations when time-dependent effects (visco-elasticity, creep, stress relaxation) in the bonding material are important and for numerous other more complicated and practically important situations that might be encountered in engineering practice.

2009-02-21

257

Glucose-sensitive polyelectrolyte nanocapsules based on layer-by-layer technique for protein drug delivery.  

Science.gov (United States)

The glucose-responsive nanocapsules [CS-NAC/p(GAMA-r-AAPBA)] were readily fabricated with modified chitosan (CS-NAC) and random glycopolymer poly(D-gluconamidoethyl methacrylate-r-3-acrylamidophenylboronic acid) p(GAMA-r-AAPBA) as the alternant multilayered polyelectrolyte hybrid shell via layer-by-layer self-assembly after etching the amino functionalized SiO2 spheres by NH4F/HF. The spherical and hollow structure of nanocapsules was confirmed by TEM analysis and there was no clear collapse found after removal of the sacrificial cores. The reversible zeta potential changes of the nanocapsule materials evaluated the reversible glucose sensitivity. Besides, this system demonstrated a good capacity for encapsulation and loading insulin entrapped in nanocapsules as model protein drug. A good biocompatibility of the material was confirmed by the cell viability. In vitro release of insulin experiments revealed that no obvious release was found in acidic condition and the release could be normally conducted at physiological pH. These results implied that it was feasible for nanocapsules to be used in controlled release drug delivery system. PMID:24068543

Guo, Honglei; Guo, Qianqian; Chu, Tianci; Zhang, Xinge; Wu, Zhongming; Yu, Demin

2014-01-01

258

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.

2010-03-21

259

Development of electrodeposited ZnTe layers as window materials in ZnTe/CdTe/CdHgTe multi-layer solar cells  

International Nuclear Information System (INIS)

Zinc telluride (ZnTe) thin films have been deposited on glass/conducting glass substrates using a low-cost electrodeposition method. The resulting films have been characterized using various techniques in order to optimize growth parameters. X-ray diffraction (XRD) has been used to identify the phases present in the films. Photoelectrochemical (PEC) cell and optical absorption measurements have been performed to determine the electrical conductivity type, and the bandgap of the layers, respectively. It has been confirmed by XRD measurement that the deposited layers mainly consist of ZnTe phases. The PEC measurements indicate that the ZnTe layers are p-type in electrical conduction and optical absorption measurements show that their bandgap is in the range 2.10-2.20 eV. p-Type ZnTe window materials have been used in CdTe based solar cell structures, following new designs of graded bandgap multi-layer solar cells. The structures of FTO/ZnTe/CdTe/metal and FTO/ZnTe/CdTe/CdHgTe/metal have been investigated. The results are presented in this paper using observed experimental data

2009-02-01

260

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

Energy Technology Data Exchange (ETDEWEB)

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

Johnson, J.S.; Westmoreland, C.G.

1982-02-02

 
 
 
 
261

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

Energy Technology Data Exchange (ETDEWEB)

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

Johnson, J.S. Jr.; Westmoreland, C.G.

1980-08-20

262

Silicon nanotubes from sacrificial silicon nanowires: fabrication and manipulation via embedding in flexible polymers  

International Nuclear Information System (INIS)

In the present work we report a simple method to fabricate Si nanotubes (NTs) starting from the growth of self-assembled sacrificial Si nanowires that, at the same time, embeds them into a polyimide matrix, allowing a very easy manipulation of these nano-objects, including removal, transfer and positioning. Our all-silicon fabrication method is completely compatible with the Si technology platform and is therefore implementable using the existing technology. Transferred NTs show good electrical contact with underlying electrodes, and relatively low resistance values have been measured. All these features demonstrate the effectiveness of the transfer method and the potentiality of the NTs in electronics. Finally, optical reflectivity of the NTs has been measured in the near UV–near IR spectral range. (paper)

2012-08-03

263

Synthesis of Au nanotubes with SiOx nanowires as sacrificial templates  

International Nuclear Information System (INIS)

Gold nanotubes with SiOx nanowires as sacrificial templates have been synthesized. SiOx nanowires were functionalized by 3-aminopropyl trimethoxysilane that generates a charged surface. The attachment of negatively charged Au nanoparticles was followed. The coverage of Au nanoparticles was initially less than 30%. Further coverage was achieved by the reduction of gold hydroxide to grow the continuous nanoshell on Au nanoparticles, which serve as nucleation sites. The final coverage of Au nanoshells on SiOx nanowires depends strongly on the relative amount of SiOx nanowires in gold hydroxide solution. Both transmission electron microscope and scanning electron microscope images revealed the formation of Au nanotubes with the removal of SiOx nanowires by etching in a dilute HF solution

2006-07-01

264

Fabrication of nano-sized metal patterns on flexible polyethylene-terephthalate substrate using bi-layer nanoimprint lithography  

International Nuclear Information System (INIS)

Polymer films are widely used as a substrate for displays and for solar cells since they are cheap, transparent and flexible, and their material properties are easy to design. Polyethylene-terephthalate (PET) is especially useful for various applications requiring transparency, flexibility and good thermal and chemical resistance. In this study, nano-sized metal patterns were fabricated on flexible PET film by using nanoimprint lithography (NIL). Water-soluble poly-vinyl alcohol (PVA) resin was used as a planarization and sacrificial layer for the lift-off process, as it does not damage the PET films and can easily be etched off by using oxygen plasma. NIL was used to fabricate the nano-sized patterns on the non-planar or flexible substrate. Finally, a nano-sized metal pattern was successfully formed by depositing the metal layer over the imprinted resist patterns and applying the lift-off process, which is economic and environmentally friendly, to the PET films.

2009-05-29

265

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

266

Electrochemical and radiochemical material transport examinations in humate-containing montmorillonite a bentonite thin layers  

International Nuclear Information System (INIS)

Various humate-containing H-bentonite layers were investigated using 137Cs ion transport and radio absorption measuring method. These processes can model radioactive contamination migration in soils exposed to acid rains. Experiment using montmorillonite and bentonite layers are discussed, and the results obtained with electrochemical and radioisotope absorption techniques are presented. (R.P.)

1999-01-01

267

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

268

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

Directory of Open Access Journals (Sweden)

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

Dr.S Ranganatha

2013-09-01

269

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

270

Review of the material properties of pyrolytic carbon coating layers in relation to QC measurements for HTR coated particle fuels  

International Nuclear Information System (INIS)

The role of coating layers in coated particle fuels is of extreme importance in view of the in-reactor performance of a fuel, of which these properties are mostly determined during a coating process. A coating process involves a chemical vapor deposition (CVD) technique which is a complex process involving chemical substances in gas phases. In order to develop a coating process, the relation between the process parameters and the resulting coating layer properties must be well understood, and during the manufacturing of coated particle fuels, these properties should be verified through a so-called Quality Control (QC) with various inspection points. In addition, the measurement results of these QC items are utilized for analyzing an in-reactor performance with a dedicated performance computer code. Therefore, in order to estimate and understand correctly the in-reactor behavior of coated particle fuels, reliable material properties should be established. While there have been significant publications regarding the material properties data for SiC coating layers and its coating technologies, only a few are available for pyrolytic carbon (PyC), particularly for a porous buffer PyC layer, though much work has been devoted to studies on the material properties of PyC, including its changes during an irradiation in the early developmental stage in the 1970's. In this work, material properties of PyC layers in a HTR coated fuel particle are reviewed by compiling and analyzing the literature data. Also, the establishment of a relationship between QC measurements and properties is attempted. (authors)

2008-06-08

271

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

International Nuclear Information System (INIS)

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

2011-07-04

272

Conceptual material design for magnetic tunneling junction cap layer for high magnetoresistance ratio  

International Nuclear Information System (INIS)

A conceptual material design for magnetic tunneling junction cap layer realizing a steep NiFe/AlOx interface is proposed. Tunnel magneto resistance stack of cap/NiFe/AlOx/CoFe/Ru/CoFe/PtMn/Ta//sub was prepared. Maximum magnetoresistance (MR) ratios of nonmagnetic-NiFeZr, Zr, Ta, Ru, and Rh caps at 0 V were 55%, 28%, 50%, 43%, and 42%, respectively. The decrease of MR ratio and the increase of resistance area product RA with Ru cap compared to Ta cap correlate with the partial oxidation of the NiFe/AlOx interface occurring in additional postannealing, which was confirmed by focused-ion-beam-transmission-electron-microscope-energy-dispersive- x-ray-fluorescence observation. Since standard electrode potential is Ta< Fe< Ni< Ru, it is supposed that NiFe with Ru cap is positively charged, the NiFe/AlOx interface is easily oxidized during annealing by negatively charged oxidizing species, and increase of RA and decrease of MR ratio occur. RA with Rh cap was even higher than that with Ru cap, consistent with the higher electrode potential of Rh than that of Ru. On the other hand, as the electrode potential of Ta is lower than NiFe, we think that NiFe with Ta cap is negatively charged, the oxidation of the NiFe/AlOx interface is suppressed, and the lower RA and higher MR ratio than those with Ru cap are obtained. Since the electrode potential of Zr is still lower than Ta, we expected an even higher MR ratio with Zr cap. However, magnetism and magnetostriction of Zr/NiFe/AlOx//sub sample changed significantly at first and saturated rapidly in sequential postannealing processes, indicating that the diffusion of Zr to NiFe proceeds at the beginning and saturates promptly. Therefore, we introduced nonmagnetic-NiFeZr alloy cap and the highest MR ratio of 55% was realized, without suffering from the diffusion of Zr. The highest MR ratio with nonmagnetic-NiFeZr cap is consistent with the lowest electrode potential of Zr, and we believe that nonmagnetic-NiFeZr cap realizes a steep NiFe/AlOx interface without the oxidation of NiFe

2006-04-15

273

Dislocation filtering in semiconductor superlattices with lattice-matched and lattice-mismatched layer materials  

International Nuclear Information System (INIS)

We investigate the ability of semiconductor superlattices to filter or block threading dislocations by growing and studying structural properties of superlattices composed of alternating layers (--100 A each) of In/sub x/Ga_1/sub -//sub x/As and In/sub y/Al_1/sub -//sub y/As. These superlattices were grown with x = y corresponding to lattice-matched compositions such that the layers have minimal strain, and xnot =y corresponding to lattice-mismatched compositions such that the layers have large coherent strains. By correlating the number of dislocations observed in optical images of the superlattices, with the amount of layer strain determined by x-ray double diffraction analysis, we investigate the effect of strain on the filtering ability. We find that both types of superlattices are effective in filtering dislocations

1986-10-27

274

Model of superconducting vortices in layered materials for the interpretation of transmission electron microscopy images  

DEFF Research Database (Denmark)

More realistic simulations of the magnetic field and electron optical phase shift associated to pancake vortices in layered high-Tc superconducting specimen require a number of layers larger than 7, the practical upper limit set by the discrete algebraic approach followed so far. This goal can be achieved by resorting to a continuum approximation of the screening layers above and below the one containing the pancake vortex. It is thus possible to increase the number of layers and to investigate more exotic vortex core structures than those represented by the pancakes pinned at tilted columnar defects. In particular it will be shown how recently observed dumbbell-like contrast features in the out-of-focus images of superconducting vortices forming a large angle with the specimen surfaces can be interpreted as due to a kinked structure of the pancakes. © 2004 The American Physical Society

Beleggia, Marco; Pozzi, G.

2004-01-01

275

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 "1"4C-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.)

1987-01-01

276

Synthesis of nested coaxial multiple-walled nanotubes by atomic layer deposition.  

Science.gov (United States)

Nested multiple-walled coaxial nanotube structures of transition metal oxides, semiconductors, and metals were successfully synthesized by atomic layer deposition (ALD) techniques utilizing nanoporous anodic aluminum oxide (AAO) as templates. In order to fabricate free-standing tube-in-tube nanostructures, successive ALD nanotubes were grown on the interior template walls of the AAO nanochannels. The coaxial nanotubes were alternated by sacrificial spacers of ALD Al(2)O(3), to be chemically removed to release the nanotubes from the AAO template. In this study, we synthesized a novel nanostructure with up to five nested coaxial nanotubes within AAO templates. This synthesis can be extended to fabricate n-times tube-in-tube nanostructures of different materials with applications in multisensors, broadband detectors, nanocapacitors, and photovoltaic cells. PMID:20085347

Gu, Diefeng; Baumgart, Helmut; Abdel-Fattah, Tarek M; Namkoong, Gon

2010-02-23

277

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)

2012-10-01

278

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

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

2012-01-01

279

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

Directory of Open Access Journals (Sweden)

Full Text Available Patterning technology of ferrite and insulating material in multilayer ceramic devices is proposed. In the conventional technology, the different ceramic materials such as the ferrite and the insulating material have been prepared in the form of the each different green sheet, and then they have been stacked each other. Otherwise the different material has filled cavities that were formed by a mechanical punching in advanced. In our proposing technology, arbitrary patterning of the different ceramic material inside the same green sheet is possible. In this process, the arbitrary shape of the through pattern is formed in the green sheet of the base material by making use of photo resist films as sacrifice patterns, and then the base material is masked by the patterned photo resist film. After filling the slurry of the different material into the through pattern of the base material passing the resist mask, the pattern of the different ceramic material in the green sheet is achieved. In the present paper, the ferrite magnetic material and the alumina-glass composite material are used. The patterned structure inside the green sheet is obtained. The slurry preparation, the thickness of the mask resist film, and the obtained structure of the green sheet are discussed.

Fumio Uchikoba

2012-07-01

280

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

Science.gov (United States)

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

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

2012-05-01

 
 
 
 
281

Determination of material properties of gas diffusion layers by numerical simulation and a comparison with experimental results  

Energy Technology Data Exchange (ETDEWEB)

There are 3 ways to determine the permeability, diffusivity and conductivity of the gas diffusion layer. These include experimental measurements performed on a material sample; numerical simulation performed on a 3D tomography image of a real material sample; and numerical simulation performed on a virtually created structure model. This presentation compared results obtained in these 3 ways with the methods used by Toray to calculate the physical properties in TGP-H-060 carbon fibre. The numerical methods used to calculate permeability, diffusivity and conductivity were applied on both tomography-based models and virtually created models. The virtual material model approach was also explained. The results were compared with measurements taken at the Paul Scherrer Institut in Switzerland. The reliability of the numerical methods and their usefulness for virtual material design was then assessed based on a comparison of these results.

Becker, J. [Fraunhofer ITWM, Kaiserslautern (Germany)

2009-07-01

282

A study of the surface erosion of zircaloy material during laser ablation process by thin layer activation technique  

Energy Technology Data Exchange (ETDEWEB)

The thin layer activation (TLA) technique was applied to study the surface erosion of zircaloy clad material during laser ablation process by producing a suitable {gamma}-ray emitting radioisotope in the clad surface using 40 MeV a-particles. This paper reports the rate of surface erosion of zircaloy as a function of deposited laser energy in the range of a few hundred of millijoules to a few kilojoule. The minimum detection limit was found to be 80 {+-} 25 nm in the measurement of surface loss of material due to laser exposure by TLA technique. (orig.)

Datta, J.; Chowdhury, D.P. [Bhabha Atomic Research Centre, Kolkata (India). Analytical Chemistry Div.; Verma, Rakesh [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Analytical Chemistry Div.; Nilaya, J.P.; Biswas, D.J. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Laser and Plasma Technology Div.; Gantayet, L.M. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Beam Technology Development Group

2013-03-01

283

Highly efficient single-layer phosphorescent white organic light-emitting diodes using a spirofluorene-based host material.  

Science.gov (United States)

Highly efficient phosphorescent white organic light-emitting diodes (PHWOLEDs) were developed by the doping of phosphorescent blue and red dopants in a spirofluorene-based phosphine oxide host material. A high quantum efficiency of 18.3% and a current efficiency of 34.2 cd/A at 100 cd/m(2) were obtained from the PHWOLED with the spirofluorene-based phosphine oxide host material. In addition, a high power efficiency of 28.3 lm/W was achieved in the PHWOLED. The wide triplet bandgap of host and charge balance in the light-emititng layer were responsible for the high efficiency. PMID:19373323

Jeon, Soon Ok; Yook, Kyoung Soo; Joo, Chul Woong; Lee, Jun Yeob

2009-02-15

284

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

Science.gov (United States)

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

Gille, J. P.

1972-01-01

285

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

286

Four-layer tin-carbon nanotube yolk-shell materials for high-performance lithium-ion batteries.  

Science.gov (United States)

All high-capacity anodes for lithium-ion (Li-ion) batteries, such as those based on tin (Sn) and silicon (Si), suffer from large volume changes during cycling with lithium ions, and their high capacities can be only achieved in the first few cycles. We design and synthesize a unique four-layer yolk-shell tin-carbon (Sn-C) nanotube array to address this problem. The shape and size of the exterior Sn?nanotube@carbon core-shell layer, the encapsulated interior Sn nanowire@carbon nanotube core-shell layer, and the filling level of each layer can be all controlled by adjusting the experimental conditions. Such a nanostructure has not been reported for any metal or metal oxide-based material. Owing to the special design of the electrode structure, the four-layer hierarchical structure demonstrates excellent Li-ion storage properties in terms of high capacity, long cycle life, and high rate performance. PMID:24648261

Chen, Peng; Wu, Fengdan; Wang, Yong

2014-05-01

287

Thin layer chromatography-application in qualitative analysis on presence of coumarins and flavonoids in plant material.  

Science.gov (United States)

Drugs, natural medicinal plant, animals and mineral materials, have a large and various application in official pharmacy and medicine. Carriers of multilateral pharmacological effects that those drugs shown, are chemically define as active components that are present in them. Methods of qualitative and quantitative analysis are used for the chemical investigation of components that drugs contain. Method of thin layer chromatography has been shown as very reliable. According to the chemical investigation of single drugs, it is possible to define a group of compound or single compound comparing them with standards. Relating to the usage of method of thin layer chromatography, it has been carried out investigation on presence of coumarins and flavonoids in domestic plant material that have wide everyday usage. Coumarins and flavonoids from the point of view of chemical belonging are phenol derivatives with important pharmacological effects. Applying method of thin layer chromatography, it is detected presence of coumarins and flavonoids substances in plant material that has been tested. Anethi graveolens fructus et folium (fruit and leaf of dill), Anethum graveolens L., Apiaceae, Avenae sativae fructus (fruit of oats), Avena sativa L., Poaceae and Asperulae odoratae herba (sweet woodruff), Asperula odorata L., Rubiaceae. Chromatograms are developed in systems cyclohexane-ethylacetat (13:7) and toluene-ether (1:1) saturated with 10% acetic acid, and visualisation by observing on UV lamp (254 and 366 nm), spraying with reagents KOH (10% ethanol solution) and diphenylboryloxyethylamine (1% methanol solution). PMID:16232145

Kovac-Besovi?, Elvira E; Duri?, Kemal

2003-07-01

288

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

289

Protective layer for nuclear fuel container and powdery spray material for its manufacture  

International Nuclear Information System (INIS)

The protective layer consists of at least 40 weight% of at least one intermetallic boron compound, (with a minimal boron content of 5 weight%), minutely dispersed in a matrix consisting essentially of iron, nickel or an alloy of iron and/or nickel and/or chromium. The thickness of the layer corresponds to a boron-10 isotope content of at least 5 mg/cm2/. By this means, a high neutron capture cross section combined with very good long-time corrosion resistance and mechanical properties is achieved

1986-01-01

290

Ab initio synthesis of single-layer III-V materials  

Science.gov (United States)

The discovery of a novel material requires the identification of the material's composition as well as of suitable synthesis conditions. We present a data-mining approach to identify suitable substrates for the growth of two-dimensional materials and apply the method to the recently predicted two-dimensional III-V compounds. We identify several lattice-matched substrates for their epitaxial growth, stabilization, and functionalization. Density-functional calculations show that these substrates sufficiently reduce the formation energies of the metastable two-dimensional materials to make them thermodynamically stable. We show that chemical interactions of the two-dimensional materials with the substrates shift the Fermi level of these materials, resulting in doping. The large adsorption energies and strong doping indicate that these metals should provide good electrical contact to enable transport measurements and electronic applications.

Singh, Arunima K.; Zhuang, Houlong L.; Hennig, Richard G.

2014-06-01

291

Performance of a sacrificial cladding structure made of empty recyclable metal beverage cans under large-scale air blast load  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper demonstrates the use of recyclable waste products such as typical empty metal beverage cans available in the market for the protection of civil engineering structures from an explosive load. The sacrificial cladding structure was made of empty recyclable beverage cans and sandwich composite skin plates. To measure the protection efficiency of these structures large-scale air blast experiments have been conducted. To create a perfect plane shock wave the concept of shock tube was us...

Palanivelu, Sivakumar; Paepegem, Wim; Degrieck, Joris; Reymen, Bruno; Segers, Eric; Ndambi, Jean-marie; Vantomme, John; Ackeren, Johan; Wastiels, Jan; Kakogiannis, Dimitrios; Hemelrijck, Danny

2011-01-01

292

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

A novel formulation for thick-film graphite sacrificial pastes is studied in this paper. It is composed of coarse graphite powder (grain size: 25 ?m), dispersed in a vehicle consisting of polyvinyl alcohol (PVA) dissolved in a propylene glycol (PG)–glycerol (G)–water mix, which is not aggressive to thin LTCC sheets. The presented sacrificial paste has been successfully applied for fabrication of thin (<50 ?m) membranes and microchannels in low temperature co-fired ceramics (LTCC) substr...

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

2011-01-01

293

Shape-selective sieving layers on an oxide catalyst surface  

Science.gov (United States)

New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al2O3 (thickness, 0.4-0.7 nm) with ‘nanocavities’ (<2 nm in diameter) on a TiO2 photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations.

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

2012-12-01

294

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

295

Fabrication of Porous Hydroxyapatite through Combination of Sacrificial Template and Direct Foaming Techniques  

Directory of Open Access Journals (Sweden)

Full Text Available The porous hydroxyapatite (HA bioceramics were prepared through combination of sacrificial template and direct foaming techniques using PMMA granules (varied from 5 to 50wt% in content as a template and H2O2 solution (varied from 5 to 30wt% in concentration as a foaming agent, respectively. The effects of PMMA content and H2O2 concentration on final porosity, microstructure and mechanical strengths were studied. The porous samples using PMMA provided the porosity ranging from 52% to 75%, the samples using H2O2 had the porosity ranging from 82% to 85%, and the sample using both pore formers provided the porosity ranging between 84% and 90%. The higher content of PMMA and concentration of H2O2 led the porosity increased, leading to a decrease in the compressive and flexural strengths. Furthermore, this combination technique allowed interconnected pores having two levels of pore size, which were come from PMMA and H2O2. The PMMA formed the small pores with the diameter ranging between 100 and 300 ?m, while H2O2 provided the larger pores with the diameter ranging from 100 to 1,000 ?m depending on concentration.

Serena M Best

2011-04-01

296

Platinum-centered yolk-shell nanostructure formation by sacrificial nickel spacers.  

Science.gov (United States)

We have synthesized Pt@silica/nickel phyllosilicate and Pt@silica yolk-shell nanostructures from NiPt@silica core-shell particles by simple chemical treatments. Silica coating of the NiPt alloy nanoparticles via the microemulsion method yielded spherical NiPt@silica core-shell nanoparticles with an average core diameter of 6.5 nm. Under a reflux condition in water, the core-shell structure transformed into Pt@silica yolk-shell nanoparticles with branched nickel phyllosilicate, which exhibited high surface area and large pore volume. The addition of hydrochloric acid selectively etched the nickel component from the NiPt cores and yielded Pt@silica yolk-shell nanoparticles with single-crystalline platinum cores. The average diameter of the metal cores was reduced to 4.5 nm. In both cases, the nickel components behaved as sacrificial spacers and successfully formed a vacancy between the metal cores and the silica hollow shells. PMID:20481526

Park, Ji Chan; Kim, Jae Young; Heo, Eunjung; Park, Kang Hyun; Song, Hyunjoon

2010-11-01

297

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

298

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

International Nuclear Information System (INIS)

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

2011-04-21

299

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

Science.gov (United States)

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

Deng, Haixia; Belharouak, Ilias; Amine, Khalil

2012-10-02

300

Hierarchical assembly of Ti(IV)/Sn(II) co-doped SnO? nanosheets along sacrificial titanate nanowires: synthesis, characterization and electrochemical properties.  

Science.gov (United States)

Hierarchical assembly of Ti(IV)/Sn(II)-doped SnO? nanosheets along titanate nanowires serving as both sacrificial templates and a Ti(IV) source is demonstrated, using SnCl2 as a tin precursor and Sn(II) dopants and NaF as the morphology controlling agent. Excess fluoride inhibits the hydrolysis of SnCl2, promoting heterogeneous nucleation of Sn(II)-doped SnO? on the titanate nanowires due to the insufficient oxidization of Sn(II) to Sn(IV). Simultaneously, titanate nanowires are dissolved forming Ti(4+) species under the etching effect of in situ generated HF resulting in spontaneous Ti(4+) ion doping of SnO? nanosheets formed under hydrothermal conditions. Compositional analysis indicates that Ti(4+) ions are incorporated by substitution of Sn sites at a high level (16-18 at.%), with uniform distribution and no phase separation. Mössbauer spectroscopy quantified the relative content of Sn(II) and Sn(IV) in both Sn(II)-doped and Ti(IV)/Sn(II) co-doped SnO? samples. Electrochemical properties were investigated as an anode material in lithium ion batteries, demonstrating that Ti-doped SnO? nanosheets show improved cycle performance, which is attributed to the alleviation of inherent volume expansion of the SnO?-based anode materials by substituting part of Sn sites with Ti dopants. PMID:23904051

Wang, Hongkang; Xi, Liujiang; Tucek, Jiri; Zhan, Yawen; Hung, Tak Fu; Kershaw, Stephen V; Zboril, Radek; Chung, C Y; Rogach, Andrey L

2013-10-01

 
 
 
 
301

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

2007-07-01

302

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

International Nuclear Information System (INIS)

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

2004-06-01

303

Effect of Nickel Alloying Layer on Hydrogen Absorption Ability of Zr Al Getter Material  

Science.gov (United States)

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

Liu, Chao-Zhuo; Shi, Li-Qun

2004-06-01

304

Experiments on passive hypersonic boundary layer control using ultrasonically absorptive carbon-carbon material with random microstructure  

Science.gov (United States)

For the first time, the influence of ultrasonically absorptive carbon-carbon material on hypersonic laminar to turbulent boundary layer transition was investigated experimentally. A 7° half-angle blunted cone with a nose radius of 2.5 mm and a total length of 1,077 mm was tested at zero angle of attack in the High Enthalpy Shock Tunnel Göttingen of the German Aerospace Center (DLR) at Mach 7.5. One-third of the metallic model surface in circumferential direction was replaced by DLR in-house manufactured ultrasonically absorptive carbon-carbon material with random microstructure for passive transition control. The remaining model surface consisted of polished steel and served as reference surface. The model was equipped with coaxial thermocouples to determine the transition location by means of surface heat flux distribution. Flush-mounted piezoelectric fast-response pressure transducers were used to measure the pressure fluctuations in the boundary layer associated with second-mode instabilities. The free-stream unit Reynolds number was varied over a range of Re m = 1.5 × 106 m-1 to Re m = 6.4 × 106 m-1 at a stagnation enthalpy of h 0 ? 3.2 MJ/kg and a wall temperature ratio of T w/ T 0 ? 0.1. The present study revealed a clear damping of the second-mode instabilities and a delay of boundary layer transition along the ultrasonically absorptive carbon-carbon insert.

Wagner, Alexander; Kuhn, Markus; Martinez Schramm, Jan; Hannemann, Klaus

2013-10-01

305

Wafer-edge defect reduction for tri-layer materials in BEOL applications  

Science.gov (United States)

As the semiconductor feature size continues to shrink, the thickness of photo resist needs to be thinner and thinner to prevent resist features from collapse. Coupling with the need of high NA lithography for small feature patterning, both the reflectance control and the etch budget on resist thickness are becoming major challenges for lithographers. One way to simultaneously satisfy the needs of superior low reflectance, sufficient etch resistance and minimizing the resist feature collapse is adopting tri-layer lithography scheme. The tri-layer scheme has been successfully implemented in our manufacturing flow for FEOL (Front-End-of-Line) application. This work investigated the application of tri-layer scheme to BEOL (Back-End-of-Line) AlCu patterning. One critical problem met in this application is the defect that majorly originates from wafer edge after AlCu patterning. The defects were finally ascribed to the hump formation of Si-rich hard-mask by EBR (Edge Bead Removal) process. The hump of Si-rich hard-mask yields etch masking behavior during AlCu etch accordingly leads to pattern bridging or peeling of inorganic hard-mask after AlCu patterning. To reduce the defect, several evaluations were made to suppress the hump formation, including the EBR optimization, bake condition of Si-rich hard-mask, film stacking architecture of tri-layer by EBR rinse and surfactant additive added Si-rich hard-mask. A synergy effect among process factors has been proposed to effectively fix the defect problem around wafer edge.

Du, J. R.; Huang, C. H.; Yang, Elvis; Yang, T. H.; Chen, K. C.; Lu, Chih-Yuan

2011-03-01

306

Mass exchange in adjacent layers of grain material stored in silo  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents the results of a study on the process of moisture diffusion during barley grain storage in a grain storage silo. The moisture migration was caused by concentration gradient. The study was conducted using a model test station and consisted in the measurement of barley grain moisture and temperature in a silo, and in measuring the pressure exerted by the grain bulk on the silo wall. Analysis of the results showed that none of the parameters studied was stable. It was found that when the grain moisture content applied was 16% in the bottom layer and 10% in the upper layer the average value of grain moisture content in the silo increased from 13.2% to 14.1% over the ten days of the process, while with reverse positioning of the layers in the silo the corresponding increase reached 13.8%. This was due to additional precipitation of water in the course of the process of grain respiration. Moisture diffusion caused an increase in the temperature of the grain within the silo (up to 33°C at ambient temperature of 16°C. Another important effect of the moisture diffusion was the swelling of grains, which caused an increase in the pressure of the barley grain bulk against the silo wall. The highest increase in the wall load was observed at the boundary line between layers of grain of different moisture content levels. The changes in the values of the parameters under study were described by means of regression equations.

Bilański W.K.

1998-06-01

307

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Narayan, Roger J.; Adiga, Shashishekar P.; Pellin, Michael J.; Curtiss, Larry A.; Hryn, Alexander J.; Stafslien, Shane; Chisholm, Bret; Shih, Chun-che; Shih, Chun-ming; Lin, Shing-jong; Su, Yea-yang; Jin, Chunming; Zhang, Junping; Monteiro-riviere, Nancy A.; Elam, Jeffrey W.

2010-01-01

308

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

1986-01-01

309

Long-term self-assembly of inorganic layered materials influenced by the local states of the interlayer cations.  

Science.gov (United States)

A wide variety of parameters as, e.g., temperature, humidity, particle size, and cation state are known to influence the agglomeration process of two-dimensional (2D) nanosheets, called self-assembly, in inorganic layered materials. The detailed studies on which parameters are decisive and how they influence the self-assembly, however, have not been performed yet. Here, the long-term self-assembly was studied for layered stevensite and hectorite, and compared with our previous data of saponite for elucidating an influence of local states of the interlayer cations. The results were analyzed with respect to a recently established rheological model, in which 2D nanosheets migrate parallel to the layer direction aided by water molecules as lubricants [K. Sato et al., J. Phys. Chem. C, 2012, 116, 22954]. With decreasing the strength of the local electric fields facing to the interlayer spaces, cation positions split into two or three, which makes the distribution of water molecules more uniformly. These water molecules enhance the rheological motion of the 2D nanosheets parallel to the layer direction, thus accelerating the self-assembly process. PMID:24770790

Sato, Kiminori; Numata, Kazuomi; Dai, Weili; Hunger, Michael

2014-06-14

310

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

Directory of Open Access Journals (Sweden)

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

Teofil-Danut Silipas

2011-01-01

311

High-performance hierarchical LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} microspheres synthesized via a facile template-sacrificial route  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • Microsphere hierarchical LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} was fabricated. • A facile in situ route with MnO{sub 2} as the sacrificial template was developed. • Conventional co-precipitate synthesis method was compared. • The hierarchical microsphere sample exhibits superior electrochemical performance. -- Abstract: LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} microspheres have been successfully synthesized via a facile in situ route with MnO{sub 2} 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{sup ?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{sup +} and e{sup ?} diffusion, and facilitate the penetration of the electrolyte.

Xiong, Wen; Jiang, Yan; Yang, Ze [Key Laboratory for Advanced Battery Materials and System (Ministry of Education), School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Li, Dinggen [School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Huang, Yunhui, E-mail: huangyh@mail.hust.edu.cn [Key Laboratory for Advanced Battery Materials and System (Ministry of Education), School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2014-03-15

312

Molecular Sensing Ability of Layered Inorganic/Luminous Organic Nano Hybrid Solid Materials  

International Nuclear Information System (INIS)

To apply titanate nanosheet/decyltrimethlammonium/rhodamine 3B (TNS/C10TMA/R3B) hybrid material with highly luminescent ability to high performance sensor or indicator, spectroscopic properties in the absence and presence of water and/or NH3 vapors were investigated. The TNS/C10TMA/R3B hybrid material exhibited tone change of photoadsorption and photoluminescence in the presence of water vapor. Moreover, this material exhibited remarkable quenching in the presence of NH3 vapor under humid condition. It was found that this quenching was caused by an intramolecular cyclization reaction of incorporated R3B. This photoluminescence intensity decreased with an increase in NH3 concentration. This fact is that the present hybrid material has a high potential for molecular sensor or indicator.

2011-10-29

313

Molecular Sensing Ability of Layered Inorganic/Luminous Organic Nano Hybrid Solid Materials  

Energy Technology Data Exchange (ETDEWEB)

To apply titanate nanosheet/decyltrimethlammonium/rhodamine 3B (TNS/C10TMA/R3B) hybrid material with highly luminescent ability to high performance sensor or indicator, spectroscopic properties in the absence and presence of water and/or NH{sub 3} vapors were investigated. The TNS/C10TMA/R3B hybrid material exhibited tone change of photoadsorption and photoluminescence in the presence of water vapor. Moreover, this material exhibited remarkable quenching in the presence of NH{sub 3} vapor under humid condition. It was found that this quenching was caused by an intramolecular cyclization reaction of incorporated R3B. This photoluminescence intensity decreased with an increase in NH{sub 3} concentration. This fact is that the present hybrid material has a high potential for molecular sensor or indicator.

Sasai, Ryo, E-mail: rsasai@riko.shimane-u.ac.jp [1060 Nishi-Kawatsu-cho, Matue, 690-8504, Japan. Interdisciplinary Faculty of Science and Engineering, Shimane University (Japan)

2011-10-29

314

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

Scientific Electronic Library Online (English)

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

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

315

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

316

Ultrathin spinel membrane-encapsulated layered lithium-rich cathode material for advanced li-ion batteries.  

Science.gov (United States)

Lack of high-performance cathode materials has become a technological bottleneck for the commercial development of advanced Li-ion batteries. We have proposed a biomimetic design and versatile synthesis of ultrathin spinel membrane-encapsulated layered lithium-rich cathode, a modification by nanocoating. The ultrathin spinel membrane is attributed to the superior high reversible capacity (over 290 mAh g(-1)), outstanding rate capability, and excellent cycling ability of this cathode, and even the stubborn illnesses of the layered lithium-rich cathode, such as voltage decay and thermal instability, are found to be relieved as well. This cathode is feasible to construct high-energy and high-power Li-ion batteries. PMID:24844948

Wu, Feng; Li, Ning; Su, Yuefeng; Zhang, Linjing; Bao, Liying; Wang, Jing; Chen, Lai; Zheng, Yu; Dai, Liqin; Peng, Jingyuan; Chen, Shi

2014-06-11

317

Cadmium Free Buffer Layers and the Influence of their Material Properties on the Performance of Cu(In,Ga)Se2 Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

CdS is conventionally used as a buffer layer in Cu(In,Ga)Se2, CIGS, solar cells. The aim of this thesis is to substitute CdS with cadmium-free, more transparent and environmentally benign alternative buffer layers and to analyze how the material properties of alternative layers affect the solar cell performance. The alternative buffer layers have been deposited using Atomic Layer Deposition, ALD. A theoretical explanation for the success of CdS is that its conduction band, Ec, forms a small p...

Hultqvist, Adam

2010-01-01

318

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

International Nuclear Information System (INIS)

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

1985-01-01

319

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)

1996-01-01

320

Collision of a vortex ring on granular material. Part II. Erosion of the granular layer  

Science.gov (United States)

In our previous paper (part I), an experimental result was presented on the normal impact of a vortex ring on the granular layer (glass beads of diameter 0.10 mm), which was placed at a specified distance from the outlet of the vortex ring generator. The Reynolds number of the vortex ring ranged from 1000 to 6000, whereas the traveling distance ranged from 2 to 13 times of the diameter of the vortex ring generator nozzle. In part I, the deformation of the vortex ring impacting on the granular layer and the development of the secondary vortex ring were focused. In this paper (part II), the erosion of the granular surface by the vortex ring is described. Various patterns were found depending on the Reynolds number of the vortex ring and the traveling distance. Two patterns, one (grooves) which has radial striations from the central depressed region to the outer edge of the rim and the other (dimples) which is characterized by isolated small depressions around the outer edge of the rim, are examined in detail. The formation processes of these patterns are elucidated in terms of the deformation of the vortex ring.

Yoshida, Junya; Masuda, Naoya; Ito, Boku; Furuya, Takayoshi; Sano, Osamu

2012-02-01

 
 
 
 
321

Diseño de aleaciones para ánodos de sacrificio sustentables / Designing alloys for sustainable sacrificial anodes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Se presenta: un proceso de diseño de aleaciones para fabricar ánodos de sacrificio, usados en ambientes marinos; la propuesta de sustituir al In con Ag, en aleaciones Al-Zn-In, buscando sustentar el medio ambiente; y la proposición de incluir los parámetros de los procesos de fabricación de ánodos y [...] los estructurales en la normatividad sobre ánodos de sacrificio. Se manufacturaron en el laboratorio, se ensayaron y compararon ocho aleaciones Al-Zn 2% (contenido menor al que señala la norma para aleaciones con In (de 3.5 a 5%) y con Sn (de 4 a 5%), buscando mayor sustentabilidad); cuatro se alearon con In (de 0.59 a 0.766%) y cuatro con Ag (de 0.23 a 0.428%). Se usaron dos rapideces de enfriamiento durante la solidificación, buscando modificar la estructura y cambiar propiedades y comportamientos ante la corrosión -el potencial de corrosión, la rapidez de corrosión, la activación del ánodo, el tipo de corrosión y la eficiencia de corriente-. se evaluaron las estructuras y se midieron sus potenciales; se encontró que la variación de la rapidez de enfriamiento modificó la estructura de las aleaciones, sus propiedades y comportamientos ante la corrosión y que el comportamiento general de algunas de las aleaciones con Ag es superior a las que contienen in. Las mayores eficiencias se dieron en las aleaciones con menor contenido de In (69%) y de Ag (71%). Abstract in english In this paper we present: a) a design process for manufacturing alloys to be used as sacrificial anodes in marine environments; b) the proposal to replace in with Ag, in search of alloys that could contribute to environmental sustain; and c) the proposal to include the parameters related to anode st [...] ructure and their manufacturing process in the regulation of sacrificial anodes. Eight Al-Zn 2% alloys were manufactured, tested, and compared in our laboratory. These had a lower content than the one indicated by the alloy standards - 3.5-5% and 4-5% content for in and Sn respectively- looking for a more sustainable environment. Four of them were alloyed with In (from 0.59 to 0.766%), and four with Ag (from 0.23 to 0.428%). in order to modify the structure, two cooling rates were used during solidification, seeking to modify their properties, and hence their behavior against corrosion, i.e. corrosion potential, corrosion rate, anode activation, type of corrosion and current efficiency. It was found that the variation of the cooling rate changes the structure of the alloys, their properties and corrosion behaviors. The overall behavior of some of the Ag alloys is superior to those containing In. The higher efficiencies were obtained for alloys with the lower amount of In (69%) and Ag (71%).

Salas-Banuet, Guillermo; Verduzco-Flores, Laura.

322

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

323

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

International Nuclear Information System (INIS)

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

2001-05-01

324

Toughness and subcritical crack growth in Nb/Nb3Al layered materials  

International Nuclear Information System (INIS)

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

1996-04-08

325

Facile Preparation of Hierarchical TiO2 Nano Structures: Growth Mechanism and Enhanced Photocatalytic H2 Production from Water Splitting Using Methanol as a Sacrificial Reagent.  

Science.gov (United States)

Owing to unique features, hierarchical nanostructure of TiO2 has superior photocatalytic activity. In this work a facile hydrothermal route has been explored to prepare 3D hierarchical TiO2 (3D-HTiO2), 1D/3D hybrid hierarchical TiO2 composite (HHC), and 3D hierarchical protonated titanate microspheres H2Ti2O5·H2O (3DHPTMS) at the expense of free-standing titania nanotube membrane (TiO2-Memb). It proceeded through the formation of peroxotitanium complex, a water-soluble Ti complex as an intermediate. Mechanism of formation, role of membrane crystallinity, and reaction parameters giving fine control on tuning morphology and crystal structure have been investigated systematically. Photocatalytic activities were determined by measuring the amount hydrogen generated from water splitting under UV irradiation in the presence of methanol as a sacrificial reagent. Self-assembled hierarchical titania nanostructures exhibited much superior photocatalytic activity compared to that of starting material, i.e., TiO2-Memb. Enhanced photocatalytic activity is due to characteristic morphology, increased surface area, and enhanced production of photogenerated charge carriers. PMID:24937083

Haider, Zeeshan; Kang, Young Soo

2014-07-01

326

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

Science.gov (United States)

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

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

2002-11-18

327

Layered Double Hydroxides with Intercalated Porphyrins as Photofunctional Materials: Subtle Structural Changes Modify Singlet Oxygen Production.  

Czech Academy of Sciences Publication Activity Database

of Materials. Ro?. 19, ?. 15 (2007), s. 3822-3829. ISSN 0897-4756Grant CEP: GA ?R(CZ) GA203/06/1244; GA ?R GA203/07/1424; GA AV ?R KAN100500651Grant ostatní: MESS(ES) CTQ2006-01040Výzkumný zám?r: CEZ:AV0Z40320502; CEZ:AV0Z40400503Klí?ová slova: singlet oxygenKód oboru RIV: CA - Anorganická chemieImpakt faktor: 4.883, rok: 2007

Lang, Kamil; Bezdi?ka, Petr; Bourdelande, J.L.; Hernando, J.; Jirka, Ivan; Káfu?ková, Eva; Kubát, Pavel; Mosinger, Ji?í; Wagnerová, Dana Marie

328

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 frac...

2000-01-01

329

Mechanical contact for layered anisotropic materials using a semi-analytical method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fretting and wear are recurrent problems in the field of aeronautics. Contacts the blade / disk at the compressor or high-pressure turbine aircraft engines, for example, are subjected to high stresses at high temperatures. The challenge for manufacturers is to maximize the lifetime of these components and be able to predict crack initiation. To improve handling parts, coatings are used to protect them. Materials and their mechanical properties have a direct impact on the contact and the lifet...

Bagault, Caroline

2013-01-01

330

Synthesis and characterization of a new layered cathode material for sodium ion batteries  

Science.gov (United States)

Owing to the high abundance of sodium and its low cost compared to lithium, sodium ion batteries have recently attracted a renewed interest as possible candidates for stationary and mobile energy storage devices. Herein, we present a new sodium ion intercalation material, NaxCo2/3Mn2/9Ni1/9O2, which has been synthesized by a sol-gel route in air followed by a heat treatment at 800 °C for 12 h. Its structure has been studied by X-ray diffraction showing that the material crystallized in a P2-type structure (space group P63/mmc). As far as the electrochemical properties of NaxCo2/3Mn2/9Ni1/9O2 as positive electrode are concerned, this compound offers a specific capacity of 110 mAh g-1 when cycled between 2.0 and 4.2 V vs. Na+/Na. The electrodes exhibited a good capacity retention and a coulombic efficiency exceeding 99.4%, as well as a reversible discharge capacity of 140 mAh g-1 when cycled between 2.0 and 4.5 V. These results represent a further step towards the realization of efficient sodium ion batteries, especially considering that the synthesis method proposed here is simple and cost effective and that all the electrochemical measurements were carried out without any use of additives or any optimization for both the materials and the cell components.

Doubaji, Siham; Valvo, Mario; Saadoune, Ismael; Dahbi, Mohammed; Edström, Kristina

2014-11-01

331

The Prospect of Y2SiO5-Based Materials as Protective Layer in Environmental Barrier Coatings  

Science.gov (United States)

Bulk yttrium monosilicate (Y2SiO5) possesses interesting properties, such as low thermal expansion coefficient and stability in water vapor atmospheres, which make it a promising protective layer for SiC-based composites, intended for the hottest parts in the future gas turbines. Because protective layers are commonly applied by thermal spraying techniques, it is important to analyze the changes in structure and properties that these methods may produce in yttrium silicate coatings. In this work, two SiO2-Y2O3 compositions were flame sprayed in the form of coatings and beads. In parallel, the beads were spark plasma sintered at relatively low temperature to obtain partially amorphous bulk specimens that are used as model bulk material. The thermal aging—air and water vapor atmosphere—caused extensive nucleation of Y2SiO5 and Y2Si2O7 in both the bulk and coating. The rich water vapor condition caused the selective volatilization of SiO2 from Y2Si2O7 at the specimen surface leaving a very characteristic micro-ridged Y2SiO5 zones—either in coatings or sintered bodies. An important increase in the thermal conductivity of the aged materials was measured. The results of this work may be used as a reference body for the production of Y2SiO5 coatings using thermal spraying techniques.

García, E.; Miranzo, P.; Osendi, M. I.

2013-06-01

332

Variational principles and size-dependent bounds for piezoelectric inhomogeneous materials with piezoelectric spring–layer imperfect interfaces  

Science.gov (United States)

The piezoelectric spring–layer interface model is widely used in describing some imperfect interfaces frequently involved in piezoelectric inhomogeneous materials. Typically, it is appropriate for modeling a thin, soft and low conducting interface between two bulk phases. This model stipulates that, across an interface, the displacement and electric potential are discontinuous while the traction and normal electric displacement are continuous and proportional to the displacement and electric potential jumps, respectively. In this work, the classical minimum potential principles of linear piezoelectricity are extended to piezoelectric inhomogeneous materials with piezoelectric spring–layer imperfect interfaces, and to investigating the interface effects on their effective properties. By choosing simple admissible displacement–electric displacement and stress–electric potential coupling fields, the extended Voigt and Reuss bounds can explicitly be derived for the corresponding effective properties of a transversely isotropic fiber reinforced composite which is subjected to remotely uniform in-plane electric loading and anti-plane mechanical loading. Numerical results are provided to illustrate the size-dependent features of the obtained Voigt and Reuss bounds.

Gu, S. T.; Qin, L.; Zhu, Q. Z.

2014-05-01

333

Restoring marsh elevation in a rapidly subsiding salt marsh by thin-layer deposition of dredged material  

Science.gov (United States)

Thin-layer deposition of dredged material on coastal marsh by means of high-pressure spray dredging (Jet-Spray??2) technology has been proposed as a mechanism to minimize wetland impacts associated with traditional bucket dredging technologies and to restore soil elevations in deteriorated marshes of the Mississippi River delta. The impact of spray dredging on vegetated marsh and adjacent shallow-water habitat (formerly vegetated marsh that deteriorated to open water) was evaluated in a 0.5-ha Spartina alterniflora-dominated salt marsh in coastal Louisiana. The thickness of dredged sediment deposits was determined from artificial soil marker horizons and soil elevation change was determined from sedimentation-erosion tables (SET) established prior to spraying in both sprayed and reference marshes. The vertical accretion and elevation change measurements were made simultaneously to allow for calculation of shallow (~5 m depth) subsidence (accretion minus elevation change). Measurements made immediately following spraying in July 1996 revealed that stems of S. alterniflora were knocked down by the force of the spray and covered with 23 mm of dredged material. Stems of S. alterniflora soon recovered, and by July 1997 the percent cover of S. alterniflora had increased three-fold over pre-project conditions. Thus, the layer of dredged material was thin enough to allow for survival of the S. alterniflora plants, with no subsequent colonization by plant species typical of higher marsh zones. By February 1998, 62 mm of vertical accretion accumulated at this site, and little indication of disturbance was noted. Although not statistically significant, soil elevation change was greater than accretion on average at both the spray and reference marshes, suggesting that subsurface expansion caused by increased root biomass production and/or pore water storage influence elevation in this marsh region. In the adjacent shallow water pond, 129 mm of sediment was deposited in July 1996 as a result of spraying, and despite initial shallow subsidence and continual erosion through February 1998, water bottom elevation was raised sufficiently to allow S. alterniflora to invade via rhizome growth from the adjacent marsh. Hence, thin-layer deposition of dredged material at this site was effective at restoring and maintaining marsh elevation after 1.5 years. However, if the open water sediment deposits are not soon completely stabilized via further vegetative colonization, erosion may eventually lower elevations to the level where emergent vegetation cannot persist.

Ford, M. A.; Cahoon, D. R.; Lynch, J. C.

1999-01-01

334

Highly mesoporous carbonaceous material of activated carbon beads for electric double layer capacitor  

Energy Technology Data Exchange (ETDEWEB)

The activated carbon beads (ACB) are prepared by a new preparation method, which is proposed by mixing the coal tar pitch and fumed silica powder at a certain weight ratio and activation by KOH at different weight ratios and different temperatures. The BET surface area, pore volume and average pore size are obtained based on the nitrogen adsorption isotherms at 77 K by using ASAP 2010 apparatus. The results show that our samples have much high specific surface area (SSA) of 3537 m{sup 2} g{sup -1} and high pore volume value of 305 cm{sup 3} g{sup -1}. The percentage of mesopore volume increases with the weight ratio of KOH/ACB ranging from 4% to 72% The electrochemical double layer capacitors (EDLCs) are assembled with resultant carbon electrode and electrolyte of 1 mol L{sup -1} Et4NBF4/PC. The specific capacitance of the ACB sample could be as high as 191 7 F g{sup -1} by constant current charge/discharge technique, indicating that the ACB presents good characteristics prepared by the method proposed in this work. The investigation of influence of carbon porosity structure on capacitance indicates that the SSA plays an important role on the capacitance and all the pore sizes of less than 1 {mu}. from 1 to 2 nm and larger than 2 {mu} contribute to the capacitance Mesopore structure is beneficial for the performance at high current density.

Feng, Z.H.; Xue, R.S.; Shao, X.H. [Beijing University of Chemical Technology, Beijing (China). College of Science

2010-10-01

335

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

International Nuclear Information System (INIS)

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

2006-10-25

336

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

337

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

Directory of Open Access Journals (Sweden)

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

WU-JUN ZOU

2011-08-01

338

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

International Nuclear Information System (INIS)

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

2006-01-01

339

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

340

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

 
 
 
 
341

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

Energy Technology Data Exchange (ETDEWEB)

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

Deng, Haixia; Belharouak, Ilias; Amine, Khalil

2012-10-02

342

Structures, Energetics, and Electronic Properties of Layered Materials and Nanotubes of Cadmium Chalcogenides  

Energy Technology Data Exchange (ETDEWEB)

The attractive optoelectronic properties of conducting polymers depend sensitively upon intra- and inter-polymer chain interactions, and therefore new methods to manipulate these interactions are continually being pursued. Here, we report a study of the isotopic effects of deuterium substitution on the structure, morphology, and optoelectronic properties of regioregular poly(3-hexylthiophene)s (P3HT) with an approach that combines the synthesis of deuterated materials, optoelectronic properties measurements, theoretical simulation, and neutron scattering. Selective substitutions of deuterium on the backbone or side-chains of P3HT result in distinct optoelectronic responses in P3HT/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) photovoltaics. Specifically, the weak non-covalent intermolecular interactions induced by the main-chain deuteration are shown to change the film crystallinity and morphology of P3HT/PCBM blends, and consequently reduce the short circuit current. However, decreased electronic coupling, the formation of a charge transfer state, and increased electron-phonon coupling resulting from side chain deuteration are shown to induce a remarkable reduction in open circuit voltage.

Zhou, Jia [ORNL; Huang, Jingsong [ORNL; Sumpter, Bobby G [ORNL; Kent, Paul R [ORNL; Terrones Maldonado, Mauricio [ORNL; Smith, Sean C [ORNL

2013-01-01

343

Tensile failure of bi-materials: High strain-rate simulations of thin adhesive layers on covalent substrates  

Science.gov (United States)

In the present work, we report on results of simulation-based study of mechanical response behavior and mechanisms of failure of a nanometer-scale polyimide adherent thin-film on a silicon substrate. A transition between adhesive and cohesive modes of failure with the strain rate was shown to occur in the system, subjected to high strain-rate tensile loadings. The physical mechanisms, leading to the bi-material failure, were identified for each failure mode. The study reveals that damage development and propagation are determined by a complex interplay between coupling across the interface and relaxation processes in the adherent layer. The two act in a synergistic manner to generate an instability, leading to either cohesive or adhesive failure.

Makeev, Maxim A.

2014-04-01

344

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

Science.gov (United States)

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

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

2010-01-01

345

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

346

Hierarchical assembly of Ti(iv)/Sn(ii) co-doped SnO2 nanosheets along sacrificial titanate nanowires: synthesis, characterization and electrochemical properties  

Science.gov (United States)

Hierarchical assembly of Ti(iv)/Sn(ii)-doped SnO2 nanosheets along titanate nanowires serving as both sacrificial templates and a Ti(iv) source is demonstrated, using SnCl2 as a tin precursor and Sn(ii) dopants and NaF as the morphology controlling agent. Excess fluoride inhibits the hydrolysis of SnCl2, promoting heterogeneous nucleation of Sn(ii)-doped SnO2 on the titanate nanowires due to the insufficient oxidization of Sn(ii) to Sn(iv). Simultaneously, titanate nanowires are dissolved forming Ti4+ species under the etching effect of in situ generated HF resulting in spontaneous Ti4+ ion doping of SnO2 nanosheets formed under hydrothermal conditions. Compositional analysis indicates that Ti4+ ions are incorporated by substitution of Sn sites at a high level (16-18 at.%), with uniform distribution and no phase separation. Mössbauer spectroscopy quantified the relative content of Sn(ii) and Sn(iv) in both Sn(ii)-doped and Ti(iv)/Sn(ii) co-doped SnO2 samples. Electrochemical properties were investigated as an anode material in lithium ion batteries, demonstrating that Ti-doped SnO2 nanosheets show improved cycle performance, which is attributed to the alleviation of inherent volume expansion of the SnO2-based anode materials by substituting part of Sn sites with Ti dopants.Hierarchical assembly of Ti(iv)/Sn(ii)-doped SnO2 nanosheets along titanate nanowires serving as both sacrificial templates and a Ti(iv) source is demonstrated, using SnCl2 as a tin precursor and Sn(ii) dopants and NaF as the morphology controlling agent. Excess fluoride inhibits the hydrolysis of SnCl2, promoting heterogeneous nucleation of Sn(ii)-doped SnO2 on the titanate nanowires due to the insufficient oxidization of Sn(ii) to Sn(iv). Simultaneously, titanate nanowires are dissolved forming Ti4+ species under the etching effect of in situ generated HF resulting in spontaneous Ti4+ ion doping of SnO2 nanosheets formed under hydrothermal conditions. Compositional analysis indicates that Ti4+ ions are incorporated by substitution of Sn sites at a high level (16-18 at.%), with uniform distribution and no phase separation. Mössbauer spectroscopy quantified the relative content of Sn(ii) and Sn(iv) in both Sn(ii)-doped and Ti(iv)/Sn(ii) co-doped SnO2 samples. Electrochemical properties were investigated as an anode material in lithium ion batteries, demonstrating that Ti-doped SnO2 nanosheets show improved cycle performance, which is attributed to the alleviation of inherent volume expansion of the SnO2-based anode materials by substituting part of Sn sites with Ti dopants. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02456c

Wang, Hongkang; Xi, Liujiang; Tucek, Jiri; Zhan, Yawen; Hung, Tak Fu; Kershaw, Stephen V.; Zboril, Radek; Chung, C. Y.; Rogach, Andrey L.

2013-09-01

347

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

Directory of Open Access Journals (Sweden)

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

Masahide Yasuda

2014-05-01

348

Properties of the material spontaneously formed in interfacial layer of system at extraction of rare-earth elements  

Science.gov (United States)

The wetting ability of the material formed spontaneously in the interface layer of an aqueous solution of a rare-earth element (REE) salt/solution of di-(2-ethylhexyl)phosphoric acid (D2EHPA) extraction system adhered onto a glass plate is investigated. It is found that its properties depend on the natures of the REE and the solvent, and the initial concentrations of the REE and the extracting reactant. It is shown that the material formed at the interface and adhered onto a glass plate has controlled wetting ability. The difference between the properties of interface REE formations for yttrium and cerium subgroups is established. The electric conductivity of interphase formations in the same systems is measured and shown to display an extreme dependence on time in systems with heptane but a monotonically increasing one in systems with toluene. It is shown that the electric conductivity of interphase formations diminishes sharply with an increase in the ratio of the initial concentrations of REE salt and D2EHPA. It is concluded that an increase in the relative gain of the average molar mass of interphase formations indicates coagulation and the formation of polymers.

Kizim, N. F.; Golubina, E. N.; Chekmarev, A. M.

2013-03-01

349

Heterogeneous reactions of dioctahedral smectites in illite-smectite and kaolinite-smectite mixed-layers: applications to clay materials for engineered barriers  

International Nuclear Information System (INIS)

The clay materials selected for use in the engineered barriers of the French nuclear waste isolation programme are mainly composed of dioctahedral smectite, either bentonite of Wyoming type or kaolinite-smectites most often consist of randomly stacked layers with low and high charges. In the case of the Wyoming-type bentonite, these two differently charged layers do not react in the same way when subjected to hydrothermal alteration. Overall, the low-charge smectite layers react to form high-charge smectite layers + quartz + kaolinite. Then, fixing K ions, the high-charge smectite layers are transformed into illite-smectite mixed-layers (I/S) when the temperature conditions increase. A symmetrical process is observed in natural or experimental hydrothermal conditions when the high-charge smectite layers of I/S minerals react with quartz and/or kaolinite to produce low-charge smectite layers. The chemical properties of the bentonite-engineered barriers clearly depend on the low charge/high charge smectite layer proportion, which is in turn controlled by the temperature-dependent reactions in the vicinity of the waste disposal. Although there are fewer published data on the kaolinite-smectite mixed-layered minerals (K/S), a similar low charge-high charge reaction appears to affect their smectite component. The experimental alteration of K/S leads to the formation of a low-charge beidellite with an increase in the cation-exchange capacity and in the expandability of the clay material. Thus, the properties of the engineered barrier seems to be improved after hydrothermal alteration. (Author)

1992-01-01

350

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 diffe...

Terrones, Humberto; Lo?pez-uri?as, Florentino; Terrones, Mauricio

2013-01-01

351

Effect of sulphate reducing bacteria on corrosion of Al-Zn-In-Sn sacrificial anodes in marine sediment  

Energy Technology Data Exchange (ETDEWEB)

Microbiologically influenced corrosion (MIC) of Al-Zn-In-Sn sacrificial anodes in marine sediment was investigated by exposing samples to sulphate reducing bacteria (SRB). Samples exposed to the sterile marine sediment were used as control. The results show that pitting corrosion occurs in both the sterile marine sediment and the SRB-containing marine sediment. However, the corrosion can be increased sharply by the SRB metabolic activity due to the cathodic depolarization effect. In fact, the effect is based on the consumption of hydrogen which probably results in the acceleration of galvanic corrosion between corrosion products and metal substrate. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Liu, F. [Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China); Zhang, J.; Li, W.; Duan, J.; Hou, B. [Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); Zhang, S. [College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China)

2012-05-15

352

Effect of Capping Front Layer Materials on the Penetration Resistance of Q&T Steel Welded Joints Against 7.62-mm Armor-Piercing Projectile  

Science.gov (United States)

In the present investigation, an attempt has been made to study the effect of capping front layers on the ballistic performance of shielded metal arc-welded armor steel joints which were fabricated with a chromium carbide-rich hardfaced middle layer on the buttered/beveled edge. Two different capping front layer materials were chosen for achieving better ballistic performance, namely, low hydrogen ferritic (LHF) and austenitic stainless steel (SS) fillers. On the other hand, the bottom layers are welded with SS filler for both joints. The consequent sandwiched joint served the dual purpose of weld integrity and penetration resistance of the bullet. It is observed that the penetration resistance is due to the high hardness of the hardfacing layer on the one hand and the energy-absorbing capacity of the soft backing SS weld deposits on the other hand. The complementary effect of layers successfully provided resistance to the projectile penetration. On a comparative analysis, the joint fabricated using the LHF filler capping front layer offered superior ballistic performance with respect to depth of penetration. This is mainly due to the presence of acicular ferrite along the bainitic structure in the LHF capping front layer, which caused a shallow hardness gradient along the weld center line.

Balakrishnan, M.; Balasubramanian, V.; Madhusudhan Reddy, G.; Parameswaran, P.

2013-09-01

353

Improving the fluorescence polarization method to evaluate the orientation of fluorescent systems adsorbed in ordered layered materials  

International Nuclear Information System (INIS)

The fluorescence polarization method, recently developed for the evaluation of the preferential orientation of fluorescent dyes adsorbed in layered materials [F. Lopez Arbeloa, V. Martinez Martinez, J. Photochem. Photobiol. A: Chem. 181 (2006) 44], is readapted to improve its application. Fluorescence polarization was previously obtained by recording the emission intensity for two orthogonal orientations of the emission polarizer (i.e., the horizontal and vertical polarized light) after excitation with vertical or horizontal polarized light. In the method proposed in this work, samples are excited with unpolarized light, reducing the polarization effect of the excitation light scattering at those emission wavelengths close to the excitation wavelength. Moreover, the present method decreases the effect of the orientation of other non-fluorescent species present in the system, which are active in the excitation process. Consequently, the new method is more simple, precise and sensitive. It is applied to evaluate the orientation of rhodamine 6G dye adsorbed in ordered laponite clay films with low and moderated dye loadings.

2009-11-01

354

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

Directory of Open Access Journals (Sweden)

Full Text Available A novel simplified r hcorctical solution is found lor thc strcss starcs accompanying thc proccss of cxt ri~siono f ma![ i-laycr matcrialsunder rhc conditions af axial symmetry. Thc solution i~ bawd nn ~ h mc n dcl of pcrfcct plastic material satisfying thc Trcsca yicld condition.thc Haar-Karman conditions bcing sntisficd in each layer. Thc laycrs arc chnnctcrizcd by difrercnt yicld limits and stmng plasticnonhomogeneity. In thc ncighhoi~rhoorol f thc interfaces conrinuous variation of rhc yicld limit i s a~sunicdZ. hc form of thc plastic zonc nndpsitions or the contact surfi~ccss eparating rhc laycrs nrc assumcd. Shcaring strcsscs and mcan prcssurc in a longitudinal scclion o f t hccxrruded rod arc cxprcsscd in tcrms of filnctions of the axial coordinatc z. Unknown fttnctions of thc singlc coordinatc z arc dctcrmincdFrom thc yicld conditions writtcn for thc contour of thc die. Accitratc analytical relations arc dcrivcd For tllc normal strcss distribution atthc surface of contact bctwccn thc dic and thc matcrial cxlrudcd, Using thc known normal and shcar stress dislrihutions (due to Iriclion,accuratc valuc of thc lower cstimate of thc cxtrusion forcc is dctcrrnincd. Thc sotution may hc applicd lo ~ h cca scs of arbitrary numhcr oflaycrs and arbitrary h rm oithc dic. I t may bc used to a rational analysis o f ~ h pcro ccss of cxirnsiol~o f multi-lnycr cylindrical rods.

J. Piwnik

2008-03-01

355

Material properties of pyrolytic carbon layers in coated particle fuels for High Temperature Gas-cooled Reactors  

International Nuclear Information System (INIS)

Important material properties of the pyrolytic carbon (PyC) for use as coating layers of the coated particle fuel for HTGR (High Temperature Gas cooled Reactors) are analyzed and reviewed by comparing the results obtained among different works as well as by using different measurement methods. The important properties reviewed in view of the in-reactor performance in this work are structure, density and porosity, anisotropy, Young's modulus (E), fracture stress and hardness as well as their changes upon irradiation by neutron. Results of the review indicate that the post-irradiation density increases as the pre-irradiation density increases in general leading to a densification by neutron irradiation. Also, the Young's modulus increases as the pre-irradiation density increases, but depending on the source gas of the PyC coating, these variations are quite different. The fracture stress shows an increasing tendency with increasing pre-irradiation density and neutron fluence level, but the data obtained from the literature in this review is scattered to a large extent. (authors)

2011-05-02

356

Changes in Material Properties of PyC Coating Layers by Neutron Irradiation in HTR Coated Particle Fuel: I. Dimensional Change  

International Nuclear Information System (INIS)

It is well known that the TRISO(tri-isotropic)-coated fuel particle for a HTR(High Temperature gas-cooled Reactor) has a diameter of about 1 mm, composed of a nuclear fuel kernel and four different outer coating layers, consisting of a buffer PyC (pyrolytic carbon) layer, inner PyC layer, SiC layer, and outer PyC layer with different coating thicknesses following a specific fuel design. The fuel kernel is a source for a heat generation by a nuclear fission of fissile uranium. The role of each of the four coating layers is different in view of retaining the generated fission products and other interactions during in-reactor service. Among these coating layers, PyC properties are scarcely in agreement among various investigators and the dependency of their changes upon the deposition condition is comparatively large due to their additional anisotropic properties. While a recent review work has contributed to a clear relationship between the material properties and QC measurements, an integration of the data and modeling on the irradiation behavior of PyC coating layers remains at the preliminary stage since the middle of 1970's for the early BISO design. In this work, an attempted was made to analyze the existing data of the experimental results of the material property change upon neutron irradiations of PyC coating layer obtained from various experiments performed in early periods of the HTR coated particle development by collecting and comparing the different data, mainly in the dimensional aspect

2008-10-01

357

Changes in Material Properties of PyC Coating Layers by Neutron Irradiation in HTR Coated Particle Fuel: I. Dimensional Change  

Energy Technology Data Exchange (ETDEWEB)

It is well known that the TRISO(tri-isotropic)-coated fuel particle for a HTR(High Temperature gas-cooled Reactor) has a diameter of about 1 mm, composed of a nuclear fuel kernel and four different outer coating layers, consisting of a buffer PyC (pyrolytic carbon) layer, inner PyC layer, SiC layer, and outer PyC layer with different coating thicknesses following a specific fuel design. The fuel kernel is a source for a heat generation by a nuclear fission of fissile uranium. The role of each of the four coating layers is different in view of retaining the generated fission products and other interactions during in-reactor service. Among these coating layers, PyC properties are scarcely in agreement among various investigators and the dependency of their changes upon the deposition condition is comparatively large due to their additional anisotropic properties. While a recent review work has contributed to a clear relationship between the material properties and QC measurements, an integration of the data and modeling on the irradiation behavior of PyC coating layers remains at the preliminary stage since the middle of 1970's for the early BISO design. In this work, an attempted was made to analyze the existing data of the experimental results of the material property change upon neutron irradiations of PyC coating layer obtained from various experiments performed in early periods of the HTR coated particle development by collecting and comparing the different data, mainly in the dimensional aspect.

Lee, Young Woo; Kim, Young Min; Kim, Woong Ki; Kim, Won Ju; Cho, Moon Sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2008-10-15

358

Hybrid magnetic/superconducting materials obtained by insertion of a single-molecule magnet into TaS{sub 2} layers  

Energy Technology Data Exchange (ETDEWEB)

A material in which superconducting and magnetic properties coexist is synthesized by the intercalation of single-molecule magnets into the layered structure of a group V metal dichalcogenide. A molecule-based/solid-state hybrid strategy is here employed, proving as a promising chemical approach for preparing new materials in which superconductivity coexists with different molecule-intrinsic functionalities. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Coronado, Eugenio; Navarro-Moratalla, Efren [Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Paterna (Spain); Marti-Gastaldo, Carlos [Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Paterna (Spain); Department of Chemistry, University of Liverpool, Liverpool (United Kingdom); Burzuri, Enrique; Camon, Agustin; Luis, Fernando [Instituto de Ciencia de Materiales de Aragon (ICMA/CSIC), Universidad de Zaragoza (Spain)

2011-11-16

359

Templated synthesis of nitrogen-enriched nanoporous carbon materials from porogenic organic precursors prepared by ATRP.  

Science.gov (United States)

A facile templated synthesis of functional nanocarbon materials with well-defined spherical mesopores is developed using all-organic porogenic precursors comprised of hairy nanoparticles with nitrogen-rich polyacrylonitrile shells grafted from sacrificial cross-linked poly(methyl methacrylate) cores (xPMMA-g-PAN). Such shape-persistent all-organic nanostructured precursors, prepared using atom transfer radical polymerization (ATRP), assure robust formation of template nanostructures with continuous PAN precursor matrix over wide range of compositions, and allow for removal of the sacrificial template through simple thermal decomposition. Carbon materials prepared using this method combine nitrogen enrichment with hierarchical nanostructure comprised of microporous carbon matrix interspersed with mesopores originating from sacrificial xPMMA cores, and thus perform well as CO2 adsorbents and as supercapacitor electrodes. PMID:24596246

Wu, Dingcai; Li, Zhenghui; Zhong, Mingjiang; Kowalewski, Tomasz; Matyjaszewski, Krzysztof

2014-04-01

360

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

Energy Technology Data Exchange (ETDEWEB)

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

Masuda, Naoya; Yoshida, Junya; Ito, Boku; Furuya, Takayoshi; Sano, Osamu, E-mail: sano@cc.tuat.ac.jp [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)

2012-02-01

 
 
 
 
361

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

Science.gov (United States)

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

Masuda, Naoya; Yoshida, Junya; Ito, Boku; Furuya, Takayoshi; Sano, Osamu

2012-02-01

362

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

Science.gov (United States)

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

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

2014-03-25

363

Thermal shock resistance and the mechanical properties of the refractory materials based on zirconium and cerium dioxides with layered-granular structure  

International Nuclear Information System (INIS)

This paper presents the results of investigations into the effect of the technological parameters on certain properties of the ZrO2 - and CeO2-based materials having a layeredgranular structure. Specimens were obtained by compacting the charge consisting of layered cubic granules and subsequent sintering. In order to determine the properties of the materials used for the composite electrode, four types of charges were prepared. After carrying out the experimental plan and the statistical analysis of the experimental data, the authors obtained the regression equations that satisfactorily describe the effect of the technological process variables and the types of the initial powders in the layers on the properties being studied. A comparative statement of the properties is given and the data analysis shows that the ultimate tensile strength of the layered-granular material is higher than that of the granular material by 1.5-2 times, and at the same time, its porosity is less by 1.3-1.5 times

1986-05-01

364

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

Energy Technology Data Exchange (ETDEWEB)

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

Sugiyama, K., E-mail: kazuyoshi.sugiyama@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Porosnicu, C. [National Institute for Laser, Plasma and Radiation Physics, EURATOM-MEdC Association, 077125 Bucharest (Romania); Jacob, W.; Roth, J.; Dürbeck, Th. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Jepu, I.; Lungu, C.P. [National Institute for Laser, Plasma and Radiation Physics, EURATOM-MEdC Association, 077125 Bucharest (Romania)

2013-07-15

365

Effect of various buffer-layer structures on the material quality and dislocation density of high composition Al/sub x/Ga/sub 1/. sqrt. /sub x/As laser material grown by metalorganic chemical vapor deposition  

Energy Technology Data Exchange (ETDEWEB)

The effect of various types of buffer layers on the generation and propagation of dislocations in epitaxial layers of high composition (x = 0.85) Al/sub x/Ga/sub 1/..sqrt../sub x/As grown by metalorganic chemical vapor deposition (MOCVD) on horizontal Bridgman (HB) and liquid-encapsulated Czochralski (LEC) substrates is examined. Bulk epilayers of high composition (x = 0.85) Al/sub x/Ga/sub 1/..sqrt../sub x/As and graded-barrier quantum-well laser structures with confining layers of the same composition were grown simultaneously on high-qualitylow etch-pit density (EPD) HB substrates and comparatively lower qualityhigh EPD LEC substrates with one of four types of compositionally graded andor superlattice buffer-layer structures. The bulk material was characterized by delineation and measurement of surface EPD and the observation of overall surface morphology. Data are also presented on the device characteristics of graded-barrier quantum-well laser diodes grown with these same buffer layers in order to determine the correlation between dislocation density and laser threshold current. The various buffer-layer structures were seen to be effective in reducing the defect density and improving the surface morphology of high composition epilayers grown on both HB and LEC substrates. The threshold-current density of the laser diodes, however, was independent of both the type of prelayer andor substrate utilized

Givens, M.E.; Coleman, J.J.; Zmudzinski, C.A.; Bryan, R.P.; Emanuel, M.A.; Miller, L.M.

1988-05-15

366

Improvement of photovoltaic performances of organic thin-film solar cells by fast electron mobility oxadiazole as an exciton blocking layer material  

Energy Technology Data Exchange (ETDEWEB)

We demonstrated improvements of photovoltaic performances of organic thin-film solar cells using an oxadiazole compound (Bpy-OXD) as an exciton blocking layer (EBL) material. Due to fast electron mobility of Bpy-OXD of above 10{sup -3} cm{sup 2}/Vs, the photovoltaic cell with Bpy-OXD showed higher performance than that with bathocuproine, a conventional EBL material. High amorphous nature of Bpy-OXD with high glass transition temperature of 106 C probably also caused a part of the improvements because of protecting photovoltaic layers from damaging during upper metal electrode deposition. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Ichikawa, Musubu; Shimizu, Chieko; Koyama, Toshiki; Taniguchi, Yoshio [Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokita, Ueda City, Nagano 386-8567 (Japan)

2008-05-15

367

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-02-15

368

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

International Nuclear Information System (INIS)

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

2014-02-15

369

Thin layer activation technique for the determination of surface wear in zircaloy material used in primary coolant channel in nuclear reactors  

International Nuclear Information System (INIS)

Thin layer activation (TLA) technique is a very sensitive and accurate nuclear technique for the determination of surface wear in micron order in the engineering components. TLA technique has been developed and standardised using 40 Mev ?-particles from Variable Energy Cyclotron (VEC) machine at Calcutta. It has been first applied successfully in Fe and Ni based alloy materials. The application of TLA technique with methodology in zircaloy material to determine the surface wear is presented here in brief and the sensitivity of the wear measurement is found to be 0.2 ?m. (author)

1998-02-01

370

Effect of zinc sacrificial anode degradation on the defence system of the Pacific oyster, Crassostrea gigas: chronic and acute exposures.  

Science.gov (United States)

Two types of exposures were performed to assess the effects of zinc released from sacrificial anode degradation: a chronic exposure, in which oysters were exposed to 0.53±0.04 mg Zn L(-1) for 10 weeks, and an acute exposure, where oysters were exposed to 10.2±1.2 mg Zn L(-1) for 1 week. At the end of the acute exposure experiment, 81.8% mortality was recorded. In contrast, no mortality was detected after 10 weeks exposure. Moreover, all of the immune system biomarkers studied, except the number of circulating haemocytes, were stimulated by a moderate level of zinc and inhibited by a high level. Our exposure conditions did not induce SOD or MXR mRNA expression in gills and digestive gland. However, an increase of MT mRNA is observed in these tissues. The results indicate that oysters are sensitive to acute zinc toxicity but are only moderately affected by a mild zinc concentration. PMID:22770699

Mottin, Elmina; Caplat, Christelle; Latire, Thomas; Mottier, Antoine; Mahaut, Marie-Laure; Costil, Katherine; Barillier, Daniel; Lebel, Jean-Marc; Serpentini, Antoine

2012-09-01

371

Sacrificial spacer and non-covalent routes toward the molecular imprinting of 'poorly-functionalized' N-heterocycles  

Energy Technology Data Exchange (ETDEWEB)

A comparison of three different methods for the imprinting of small aromatic heterocycles containing only a single nitrogen atom, for the preparation of specific analytical phases, was carried out. A conventional non-covalent approach to the imprinting of pyridine using methacrylic acid as the functional monomer was compared with two sacrificial spacer methods, in which heterocycles were imprinted as covalent template analogues. The results of binding experiments showed that discrimination based on ligand size was possible when polymers were prepared using a silyl ester-based template. The most selective polymer was able to bind pyridine in preference to quinoline or acridine which is opposite to the trend predicted by the pK{sub HB} values for the three ligands. Curve fitting of the isotherm for pyridine binding to this polymer to the Langmuir model gave an approximate K{sub d} of 1.1{+-}0.1 mM and a binding site concentration of 57{+-}2 mmol g{sup -1}. Acridine binding did not show saturation behaviour and was non-specific and cooperative in nature.

Kirsch, N.; Alexander, C.; Davies, S.; Whitcombe, M.J

2004-02-16

372

Sacrificial spacer and non-covalent routes toward the molecular imprinting of 'poorly-functionalized' N-heterocycles  

International Nuclear Information System (INIS)

A comparison of three different methods for the imprinting of small aromatic heterocycles containing only a single nitrogen atom, for the preparation of specific analytical phases, was carried out. A conventional non-covalent approach to the imprinting of pyridine using methacrylic acid as the functional monomer was compared with two sacrificial spacer methods, in which heterocycles were imprinted as covalent template analogues. The results of binding experiments showed that discrimination based on ligand size was possible when polymers were prepared using a silyl ester-based template. The most selective polymer was able to bind pyridine in preference to quinoline or acridine which is opposite to the trend predicted by the pKHB values for the three ligands. Curve fitting of the isotherm for pyridine binding to this polymer to the Langmuir model gave an approximate Kd of 1.1±0.1 mM and a binding site concentration of 57±2 mmol g-1. Acridine binding did not show saturation behaviour and was non-specific and cooperative in nature

2004-02-16

373

Catalyst-free direct growth of a single to a few layers of graphene on a germanium nanowire for the anode material of a lithium battery.  

Science.gov (United States)

Direct growth of a single to a few layers of graphene on a germanium nanowire (Gr/Ge NW; see picture) was achieved by a metal-catalyst-free chemical vapor deposition (CVD) process. The Gr/Ge NW was used as anode in a lithium ion battery. This material has a specific capacity of 1059 mA h g(-1) at 4.0 C, a long cycle life over 200 cycles, and a high capacity retention of 90%. PMID:23616396

Kim, Hyungki; Son, Yoonkook; Park, Chibeom; Cho, Jaephil; Choi, Hee Cheul

2013-06-01

374

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

International Nuclear Information System (INIS)

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

1999-10-01

375

Analysis of the characteristics of a white organic LED using the newly synthesized blue material methyl-DPVT by varying the thickness of the DPVBi layer  

International Nuclear Information System (INIS)

A two-wavelength type of white organic light-emitting diode (OLED) having a blue/orange emitting layer was fabricated by synthesizing Methyl-DPVT, a new derivative of the blue-emitting material DPVBi on the market. The white-emission of the two-wavelength type was successfully obtained by representing not only blue emission by using DPVBi but also orange emission by using methyl-DPVT as a host material and Rubrene as a guest material. The basic structure of the fabricated white OLED is glass/ITO/NPB(150 A)/DPVBi/methyl-DPVT :Rubrene [2.0 wt%](100 A)/BCP(70 A)/Alq3(150 A)/Al(600 A). To evaluate the characteristics of the devices, we varied the thickness of the DPVBi layer from 100 A to 80 A to 60 A. A nearly pure white-emission was obtained in CIE coordinates of (0.3327, 0.3397) when the DPVBi layer was 60-A thick at an applied voltage of 11 V. The device started to operate at 1 V and to emit light at 2.5 V. The external quantum efficiency was above 0.5 % both when almost all of the current was injected and the applied voltage was over 10 V. A superior maximum quantum effciency of 0.746 % was obtained at an applied voltage of 18.5 V.

2004-08-01

376

Material analysis of PVD-grown indium sulphide buffer layers for Cu(In,Ga)Se2-based solar cells  

International Nuclear Information System (INIS)

This paper is devoted to an X-ray photoelectron spectroscopy (XPS) study of Cu(In,Ga)Se2 (CIGSe)/In2S3 structures. The indium sulphide layers are grown by physical vapor deposition (PVD) in which indium and sulfur are evaporated on the substrates at a temperature T s. This as-deposited thin films are then heated at 200 deg. C for 1 min. A 12.4% efficiency champion cell has been achieved using this process. The XPS study reveals that copper diffuses from the chalcopyrite absorber towards the indium sulphide layer during this synthesis process. The amount of copper strongly depends on T s; the higher T s, the more copper is diffused. This observation is then correlated with the solar cell performance to conclude that a significant Cu-diffusion inhibits the formation of a high-quality junction between the Cu(In,Ga)Se2 and the buffer layer

2005-06-01

377

3D hierarchical computational model of wood as a cellular material with fibril reinforced, heterogeneous multiple layers  

DEFF Research Database (Denmark)

A 3D hierarchical computational model of deformation and stiffness of wood, which takes into account the structures of wood at several scale levels (cellularity, multilayered nature of cell walls, composite-like structures of the wall layers) is developed. At the mesoscale, the softwood cell is presented as a 3D hexagon-shape-tube with multilayered walls. The layers in the softwood cell are considered as considered as composite reinforced by microfibrils (celluloses). The elastic properties of the layers are determined with Halpinâ??Tsai equations, and introduced into mesoscale finite element cellular model. With the use of the developed hierarchical model, the influence of the microstructure, including microfibril angles (MFAs, which characterizes the orientation of the cellulose fibrils with respect to the cell axis), the thickness of the cell wall, the shape of the cell cross-section and the cell dimension (wood density), on the elastic properties of softwood was studied.

Qing, Hai; Mishnaevsky, Leon

2009-01-01

378

Thin Al2O3 barrier coatings grown on bio-based packaging materials by atomic layer deposition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Growing environmental concerns related to the use of synthetic non-biodegradable polymers in the packaging industry have led to the need for new, especially bio-based, materials. Currently, petroleum-based synthetic polymers are widely used due to their relatively low cost and high performance. Biodegradable plastics and fibre-based materials have been proposed as a solution to the waste problems related to these synthetic polymers. Fibre-based packaging materials have many advantages over th...

Hirvikorpi, Terhi

2011-01-01

379

Synthesis and Characterization of a Layered Manganese Oxide: Materials Chemistry for the Inorganic or Instrumental Methods Lab  

Science.gov (United States)

A three-week laboratory project involving synthesis and characterization of a layered manganese oxide provides an excellent vehicle for teaching important concepts of inorganic chemistry and instrumental methods related to non-molecular systems. Na-birnessite is an easily prepared manganese oxide with a 7 A interlayer spacing and Na[superscript +]…

Ching, Stanton; Neupane, Ram P.; Gray, Timothy P.

2006-01-01

380

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

Directory of Open Access Journals (Sweden)

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

Barkawi Sahari

2013-01-01

 
 
 
 
381

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

International Nuclear Information System (INIS)

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

2005-07-01

382

Effect of the method of production of an Ni3Al/Mo layered composite material on its structure and properties  

Science.gov (United States)

A stack of alternating 25 100-?-thick Ni3Al plates and 28 200-?m-thick Mo plates is subjected to hot isostatic pressing (HIP) at a temperature T = 1200°C and a pressure P = 150 MPa for ? = 2.5 h followed by hot rolling at 1050 950°C to a thickness of 2.3 mm. The stack is then subjected to cold rolling (CR) to a thickness of 0.5 mm without intermediate annealing, subsequent annealing during HIP at T = 1200°C, P = 150 MPa, and ? = 2.5 h, and CR to a thickness of 0.22 mm. Upon CR at a strain ? changing from 80.8 to 95.8%, the following specific structure forms in the longitudinal direction: molybdenum layers acquire a wavelike structure, can contact with each other, form “cells,” and retain almost the same thickness, and Ni3Al alloy layers are rejected between the molybdenum layers to form a regular structure made of alternating thickenings and thinnings across the rolling direction. Annealing during HIP and subsequent CR to ? = 98.2% lead to the formation of zones with a broken alternation of layers in the longitudinal and transverse directions, which is related to different strain resistances of the (more refractory) molybdenum and Ni3Al layers at 20°C. The adhesion between the layers is good, and no intermediate phases form at the interface. The ultimate bending strength of the 2.3-mm-thick workpiece at 20°C is 1000 ± 100 MPa, and the prepared material has a plasticity margin.

Povarova, K. B.; Burmistrov, V. I.; Skachkov, O. A.; Antonova, A. V.; Karelin, F. R.; Choporov, V. F.; Bannykh, I. O.

2008-04-01

383

Materials  

...Biosensors Brain Sciences Buildings Cancers Catalysts Cells Challenges Chemosensors Children Chromatography Climate Coatings Computation Computers Cosmetics Crystals Dentistry Journal Diagnostics Diseases Diversity Econometrics Economies ...it/research/amd/staff/biasiol.htm Interests: compound semiconductor thin films and nanostructures; crystal growth and epitaxy; kinetics of epitaxial growth;...composite materials; waste recycling; carbon nanotubes; electrophoretic deposition; vascularization; bioceramics; biofabrication; bioactive coatings; drug delivery Contribution: Special Issue: Tissue Engineering Scaffolds ...ca/~dchen/ Interests: mechanical properties; fatigue; fracture; deformation; microstructural characterization; welding and joining; lightweight materials (magnesium alloys, aluminum alloys, titanium ...

384

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

International Nuclear Information System (INIS)

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

2010-05-01

385

On the mechanical stress of Zr, Zry, and other materials due to the formation of oxide layers  

International Nuclear Information System (INIS)

Several mechanisms are indicated which during oxidation of sheets, tubes, and cylinders of pure metals and alloys might lead to plastic deformation of the remaining uncorroded cross section. Some experimental methods are described which allow evaluation of stresses occurring in oxide layers. The main reason for the creep deformation of flat and tubular specimens made of Zr and Zr alloys lies in the stresses that arise from volume increase due to the growth of oxide layers. Plastic deformations of the sheet metal specimens can be up to 100% and are anisotropic. In tubular specimens the changes in geometry (axial, radial) are much smaller in the course of oxidation and attain 2% at the maximum for Zr- or Zry-tubes and go up to 10% for Ta-tubes when no differential pressure is applied simultaneously. (orig.)

1977-01-01

386

An approach to achieve layered spintronics material using brownmillerite compound Ca2.5Sr0.5GaMn2O8  

Science.gov (United States)

Magnetic and magnetotransport properties of the naturally occurring layered compounds Ca2.5- x La x Sr0.5GaMn2O8 ( x = 0, 0.05, 0.075, and 0.1) have been reported. We have succeeded to introduce ferromagnetic ordering in the pure antiferromagnetic system Ca2.5Sr0.5GaMn2O8 by varying the ratio between Mn3+ and Mn4+ ions. The experimental results of magnetization, magnetoresistance, and neutron diffraction were interpreted on the basis of an electronic phase separation model, where a formation of ferromagnetic clusters (