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1

Metallic multilayers at the nanoscale.  

National Technical Information Service (NTIS)

The development of multilayer structures has been driven by a wide range of commercial applications requiring enhanced material behaviors. Innovations in physical vapor deposition technologies, in particular magnetron sputtering, have enabled the synthesi...

A. F. Jankowski

1994-01-01

2

Investigation of intermixing in TiAlN\\/VN nanoscale multilayer coatings by energy-filtered TEM  

Microsoft Academic Search

We employ high-resolution energy-filtered cross-sectional transmission electron microscopy (EFTEM) to estimate the degree of layer intermixing in a TiAlN\\/VN low friction, wear-resistant nanoscale multilayers with a periodicity of approximately 4 nm grown by industrial-scale unbalanced magnetron ion-assisted PVD. Coatings are examined by high-resolution TEM imaging. A series of high-resolution elemental distribution maps are obtained by tuning the electron energy-loss imaging

H. Meidia; A. G. Cullis; C. Schönjahn; W. D. Münz; J. M. Rodenburg

2002-01-01

3

Multifunctional nano-multilayered AlTiN\\/Cu PVD coating for machining of Inconel 718 superalloy  

Microsoft Academic Search

Machining of Ni-based aerospace alloys is one of the major challenges of modern manufacturing. Application of cemented carbide tooling with nano-multilayered AlTiN\\/Cu PVD coating results in a significant tool life improvement under conditions of turning the hard-to-machine aerospace Ni-based Inconel 718 superalloy. Studies of the structure, properties, tribological and wear performance of the nano-multilayered AlTiN\\/Cu PVD coating have been performed.

G. S. Fox-Rabinovich; K. Yamamoto; M. H. Aguirre; D. G. Cahill; S. C. Veldhuis; A. Biksa; G. Dosbaeva; L. S. Shuster

2010-01-01

4

Characterisation of tribocorrosion behaviour of multilayer PVD coatings.  

PubMed

The effect of repassivation on tribocorrosion behaviour of two multilayer coatings of different structures is studied experimentally by measuring the variation of instantaneous open-circuit potential during friction. One coating consists of alternating Cr and CrN layers, while another consists of alternated layers of CrN and ZrN. Analysis of the results showed that friction force, i.e. the rate of the mechanical energy supplied to the material in the contact zone, has no direct influence on the tribocorrosion behaviour; however, the wear rate does strongly influence the tribocorrosion. A simple phenomenological model of repassivation of the multilayer coating is developed assuming "surface coverage" approach. This model establishes the relationship between the rate of mechanical activation of material by friction and the behaviour of the open-circuit potential. PMID:20204333

Bayón, R; Nevshupa, R; Zubizarreta, C; Ruiz de Gopegui, U; Barriga, J; Igartua, A

2010-04-01

5

Origin of cracking in nanoscale Cu/Ta multilayers  

SciTech Connect

Cracking behaviors in nanoscale Cu/Ta multilayers bonded to polyimide substrates have been investigated by uniaxial tensile tests. Experimental results show that cracks originate from the localized deformation regions associated with aligned grain boundaries. Microscopical observations suggest that the alignment of the grain boundaries is caused by local grain boundary sliding and grain rotation, which resulted in the in-plane and out-of-plane cooperative movements of the grains in the multilayers. From the localized damage regions, shear fracture in the through-thickness direction occurred in the nanoscale Cu/Ta multilayer.

Zhang, G. P.; Zhu, X. F.; Tan, J.; Liu, Y. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Nanometrics Inc., 1550 Buckeye Drive, Milpitas, California 95035 (United States)

2006-07-24

6

High-energy phonon confinement in nanoscale metallic multilayers.  

SciTech Connect

The Fe-projected vibrational density of states g(E) in nanoscale {sup 57}Fe/M multilayers, where M=Cr, Co, Cu, Pd, or Ag was measured by nuclear resonant inelastic x-ray scattering. With decreasing Fe thickness, the high-energy phonon peak of Fe near 36 meV is suppressed for the 'soft' metals Ag, Pd, and Cu, but much less so for the 'hard' metals Co and Cr. This effect is attributed to Fe phonon confinement and interface localization due to an energy mismatch between g(E) of M and of Fe.

Cuenya, B. R.; Keune, W,; Peters, R,; Schuster, E.; Sahoo, B.; von Horsten, U.; Sturhahn, W.; Zhao, J.; Toellner, T. S.; Alp, E. E.; Bader, S. D.; Univ. of Central Florida; Univ. Duisburg-Essen

2008-01-01

7

Deposition of nanoscale multilayer CrN/NbN physical vapor deposition coatings by high power impulse magnetron sputtering  

SciTech Connect

Nanoscale multilayer CrN/NbN physical vapor deposition (PVD) coatings are gaining reputation for their high corrosion and wear resistance. However, the CrN/NbN films deposited by ABS (arc bond sputtering) technology have some limitations such as macrodroplets, porosity, and less dense structures. The novel HIPIMS (high power impulse magnetron sputtering) technique produces macroparticle-free, highly ionized metal plasma, which brings advantages in both surface pretreatment and coating deposition stages of the PVD process. In this study, nanoscale multilayer CrN/NbN PVD coatings were pretreated and deposited with HIPIMS technology and compared with those deposited by HIPIMS-UBM (unbalanced magnetron) and by the ABS technique. In all cases Cr{sup +} etching was utilized to enhance adhesion by low energy ion implantation. The coatings were deposited at 400 deg. C with substrate biased (U{sub b}) at -75 V. During coating deposition, HIPIMS produced significantly high activation of nitrogen compared to the UBM as observed with mass spectroscopy. HIPIMS-deposited coatings revealed a bilayer period of 4.1 nm (total thickness: 2.9 {mu}m) and hardness of 3025 HK{sub 0.025}. TEM results revealed droplet free, denser microstructure with (200) preferred orientation for the HIPIMS coating owing to the increased ionization as compared to the more porous structure with random orientation observed in UBM coating. The dry sliding wear coefficient (K{sub c}) of the coating was 1.8x10{sup -15} m{sup 3} N{sup -1} m{sup -1}, whereas the steady state coefficient of friction was 0.32. Potentiodynamic polarization tests revealed higher E{sub corr} values, higher pitting resistance (around potentials +400 to +600 mV), and lower corrosion current densities for HIPIMS deposited coatings as compared to the coatings deposited by ABS or HIPIMS-UBM. The corrosion behavior of the coatings qualitatively improved with the progressive use of HIPIMS from pretreatment stage to the coating deposition step.

Purandare, Y. P.; Ehiasarian, A. P.; Hovsepian, P. Eh. [NanoTechnology Centre for PVD Research, Materials and Engineering Research Institute, Howard Street, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom)

2008-03-15

8

Wear behavior of adaptive nano-multilayered AlTiN\\/Me x N PVD coatings during machining of aerospace alloys  

Microsoft Academic Search

Machining of aerospace materials is one of the major challenges of modern manufacturing. Application of nano-multilayered AlTiN\\/MexN PVD coatings (where Mex is a transition metal of V–VI groups of periodic table) to cemented carbide tooling results in a significant tool life improvement under conditions of cutting hard to machine alloys such as Ni-based Inconel 718 superalloy and Ti-based TiAl6V4 alloy.

A. Biksa; K. Yamamoto; G. Dosbaeva; S. C. Veldhuis; G. S. Fox-Rabinovich; A. Elfizy; T. Wagg; L. S. Shuster

2010-01-01

9

Surface effects on magnetic and thermodynamic properties in nanoscale multilayer ferrimagnetic films  

NASA Astrophysics Data System (ADS)

Magnetic and thermodynamic properties of a nanoscale multilayer ferrimagnetic films have been studied within the effective-field theory with correlations. The general formula for magnetization and internal energy is given. Some interesting results have been shown in the phase diagrams, for example two compensation points exist in the range of surface physical parameters. The competition among the surface exchange coupling, the surface single-ion anisotropy and the surface transverse field have great influences on the magnetization, the internal energy and the specific heat in the nanoscale multilayer ferrimagnetic films.

Jiang, Wei; Chen, Jun-nan; Ma, Ben; Wang, Zan

2014-07-01

10

Oxidation behaviour of nanoscale TiAlN\\/VN multilayer coatings  

Microsoft Academic Search

Nanoscale multilayer TiAlN\\/VN coatings were grown using combined cathodic arc\\/unbalanced magnetron deposition (arc bond sputtering, ABS) in an industrial-sized physical vapour deposition machine. The thermal behaviour of TiAlN\\/VN coatings in air was studied using thermo-gravimetric analysis, X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). Coatings were heat treated in air for 30 min at 550, 600, 638

Z. Zhou; W. M. Rainforth; D. B. Lewis; S. Creasy; J. J. Forsyth; F. Clegg; A. P. Ehiasarian; P. Eh. Hovespian; W.-D. Münz

2004-01-01

11

Nanoscale characterization of solid-supported phospholipid multilayer films  

NASA Astrophysics Data System (ADS)

Using atomic force microscopy (AFM) and the auxiliary molecular force probe (MFP) technique, we have studied the structure and nanomechanical response to nano-indentation of multilayered films of dioleoylphosphatidylcholine (DOPC) films prepared by solution spreading, spin-coating and capillary methods. Estimates for the Young's modulus for the different methods are found to be similar for sufficiently thick films. Our results demonstrate that previously reported estimates for the Young's modulus of adsorbed vesicles and lipid bilayers (membranes) by scanning probe techniques are ostensibly affected by the coupling of the substrate. Failure and self-healing of multilamellar lipid membranes is discussed.

Ngwa, Wilfred; Gao, Andrew; Cubano, Tania; Chen, Kezheng; Sahgal, Alok; Luo, Weili

2006-03-01

12

Effect of Modulation Period on the Structure and Mechanical Properties of Nanoscale W/ZrB2 Multilayered Coatings  

NASA Astrophysics Data System (ADS)

Nanoscale W/ZrB2 multilayered coatings were prepared by rf magnetron sputtering system at room temperature. SEM, XRD, surface profiler and nano-indenter were employed to investigate the influences of modulation period (?) on the microstructure and mechanical properties of the films. The results showed that nanoscaled coatings had clear multilayered structure and almost all of multilayered coatings possess higher hardness and elastic modulus than the rule-of-mixtures value of monolithic W and ZrB2 coatings. At ?=30 nm, W/ZrB2 multilayered with mixed polycrystalline texture exhibited the highest hardness of 41.5 GPa with lower residual stress.

Liu, G. Q.; Kang, Y. B.; Wang, H. Y.; Xue, F. Y.; Deng, X. Y.; Li, D. J.

13

TiAlN based nanoscale multilayer coatings designed to adapt their tribological properties at elevated temperatures  

Microsoft Academic Search

The addition of properly selected elements, coupled in nanoscale multilayer structures, can further enhance the properties of TiAlN coatings and bring new high performance. The incorporation of Y in the nanoscale pseudo-superlattice TiAlCrN\\/TiAlYN with typical period of 1.7 nm not only improves the oxidation resistance but also effectively reduces the coefficient of friction of the coating from 0.9 to 0.65

P. Eh. Hovsepian; D. B. Lewis; Q. Luo; W.-D. Münz; P. H. Mayrhofer; C. Mitterer; Z. Zhou; W. M. Rainforth

2005-01-01

14

Residual stress characterization of Al/SiC nanoscale multilayers using X-ray  

SciTech Connect

Nanolayered composites are used in a variety of applications such as wear resistant coatings, thermal barrier coatings, optical and magnetic thin films, and biological coatings. Residual stresses produced in these materials during processing play an important role in controlling their microstructure and properties. In this paper, we have studied the residual stresses in model metal-ceramic Al/SiC nanoscale multilayers produced by physical vapor deposition (magnetron sputtering). X-ray synchrotron radiation was used to measure stresses in the multilayers using the sin{sup 2} {Psi} technique. The stresses were evaluated as a function of layer thicknesses of Al and SiC and also as a function of the number of layers. The stress state of Al in the multilayer was largely compressive, compared to single layer Al stresses. This is attributed to a peening mechanism due to bombardment of the Al layers by SiC and Ar neutrals during deposition. The stress evolution was numerically modeled by a simplified peening process to qualitatively explain the Al thickness-dependent residual stresses.

Singh, DRP [Arizona State University; Deng, X. [Arizona State University; Chawla, N. [Arizona State University; Bai, J. [Brookhaven National Laboratory (BNL); Hubbard, Camden R [ORNL; Tang, G [University of New Mexico, Albuquerque; Shen, Y-L [University of New Mexico, Albuquerque

2010-01-01

15

Residual Stress Characterization of Al/SiC Nanoscale Multilayers using X-ray  

SciTech Connect

Nanolayered composites are used in a variety of applications such as wear resistant coatings, thermal barrier coatings, optical and magnetic thin films, and biological coatings. Residual stresses produced in these materials during processing play an important role in controlling their microstructure and properties. In this paper, we have studied the residual stresses in model metal-ceramic Al/SiC nanoscale multilayers produced by physical vapor deposition (magnetron sputtering). X-ray synchrotron radiation was used to measure stresses in the multilayers using the sin{sup 2} {psi} technique. The stresses were evaluated as a function of layer thicknesses of Al and SiC and also as a function of the number of layers. The stress state of Al in the multilayer was largely compressive, compared to single layer Al stresses. This is attributed to a peening mechanism due to bombardment of the Al layers by SiC and Ar neutrals during deposition. The stress evolution was numerically modeled by a simplified peening process to qualitatively explain the Al thickness-dependent residual stresses.

D Singh X Deng; N Chawla; J Bai; C Hubbard; G Tang; Y Shen

2011-12-31

16

Nanoscale characterization and magnetic property of NiCoCu/Cu multilayer nanowires.  

PubMed

NiCo/Cu multilayer nanowires have been successfully fabricated by a pulse electrodeposition technique using anodic aluminum oxide templates, and their chemistry, crystal structure and magnetic properties characterized at the nanoscale. It was found that each individual nanowire had a regular periodic structure. The NiCo/Cu nanowires also displayed a continuous morphology, smooth surface and polycrystalline fcc structure. EDX elemental mappings confirmed the presence of nickel, cobalt and copper, which appear clearly with a periodic distribution throughout the samples. Both the NiCo and Cu layers were polycrystalline and the average length of the interlayers between NiCo and Cu layers was approximately 3-4 nm. The NiCo/Cu nanowire arrays had an easy axis parallel to the length of wire and exhibited a curling magnetization reversal mechanism. This study highlights the basis morphological, structural and chemical information for NiCoCu/Cu multilayer nanowires, which is critical for their applications in nanodevices and nanoelectronics. PMID:23183276

Qi, Kuo; Li, Xinghua; Zhang, Hong; Wang, Li; Xue, Desheng; Zhang, Haoli; Zhou, Baofan; Mellors, Nigel J; Peng, Yong

2012-12-21

17

Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites  

NASA Astrophysics Data System (ADS)

In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called "interphase" between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC-TiC)n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC-TiC)n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

2013-06-01

18

Synthesis of nanoscale CN{sub x}/TiAlN multilayered coatings by ion-beam-assisted deposition  

SciTech Connect

CN{sub x}/TiAlN multilayered coatings with different nanoscale modulation periods and ratio of CN{sub x} within each period were prepared by ion-beam-assisted deposition at room temperature. Auger electron spectroscopy (AES), x-ray diffraction (XRD), and nanoindenter and a profiler were used to characterize the microstructure and mechanical properties of the coatings. The low-angle XRD pattern and AES indicated a well-defined multilayered structure of the coating. Although monolithic CN{sub x} and TiAlN coatings formed amorphous and nanocrystalline structures, respectively, the CN{sub x}/TiAlN multilayers exhibited coherent epitaxial growth due to the mutual growth-promoting effect at small CN{sub x} layer thickness (<0.6 nm). At modulation period {lambda}=2.83 nm and CN{sub x} thickness of 10% within each period, the multilayers exhibited strong TiAlN (111) and weak AlN (111) textures and showed the highest hardness (32 GPa), elastic modulus (409 GPa), and critical fracture load (65.7 mN)

Cao, M.; Li, D. J.; Deng, X. Y.; Sun, X. [College of Physics and Electronic Information Science, Tianjin Normal University, Tianjin 300387 (China); Department of Mechanical and Materials Engineering, University of Western Ontario, London, Ontario, N6A 5B9 (Canada)

2008-09-15

19

Synthesis and characterization of titanium carbide, titanium boron carbonitride, titanium boride/titanium carbide and titanium carbide/chromium carbide multilayer coatings by reactive and ion beam assisted, electron beam-physical vapor deposition (EB-PVD)  

NASA Astrophysics Data System (ADS)

The purpose of the present work was to investigate the synthesis of titanium carbide, TiBCN, TiB2/TiC and TiC/Cr23C6 multilayer coatings by several methods of electron beam-physical vapor deposition (EB-PVD) and examine the affects of various processing parameters on the properties and microstructures of the coatings. TiC was successfully deposited by reactive ion beam assisted (RIBA), EB-PVD and the results were compared to various titanium carbide coatings deposited by a variety of techniques. The affects of substrate temperature and ion beam current density were correlated with composition, hardness, changes in the lattice parameter, degree of crystallographic texture, residual stress, surface morphology, and microstructure. The average Vicker's hardness number was found to increase with increasing ion beam current density and increase over the substrate temperature range of 250°C to 650°C. The average Vicker's hardness number decreased at a substrate temperature of 750°C as a result of texturing and microstructure. The present investigation shows that the average Vicker's hardness number is not only a function of the composition, but also the microstructure including the degree of crystallographic texture. TiB2/TiC multilayer coatings were deposited by argon ion beam assisted, EB-PVD with varying number of total layers to two different film thicknesses under slightly different deposition conditions. In both cases, the hardness of the coatings increased with increasing number of total layers. The adhesion of the coatings ranged from 30 N to 50 N, with the better adhesion values obtained with the thinner coatings. The crystallographic texture coefficients of both the TiC and TiB2 layers were found to change with increasing number of total layers. The multilayer design was found to significantly affect the microstructure and grain size of the deposited coatings. The fracture toughness was found to decrease with increasing number of total layers and was attributed to the increase in hardness and reduction in the total amount of compressive stress. TiBCN coatings were synthesized by the co-evaporation of titanium, titanium diboride, and carbon (through tungsten) while simultaneously bombarding the substrate surface with a mixture of argon and nitrogen ionized gas which has not been performed to the author's knowledge. The bulk composition was determined by EPMA and suggests that TiBCN has a wide compositional range similar to TiN and TiC. The TiBCN coatings were determined to be nano-crystalline with a cubic crystallographic structure. The average Vicker's hardness number of the TiBCN coatings ranged from 2777 VHN0.050 to 3343 VHN0.050 with the highest value reported for the higher concentrations of boron. The adhesion of the coatings to WC-6wt.Co-0.3wt.%TaC was found to increase from 20 N to 52 N with decreasing compressive stress. Lastly, multilayer titanium carbide and chromium carbide coatings with varying individual layer thickness were synthesized by the co-evaporation of Ti, Cr and C through tungsten at elevated temperatures. The average Vicker's hardness number was found to increase from 1302 VHN0.050 to 2052 VHN0.050 by changing the individual layer thickness of the multilayers. In addition, the grain size, measured compressive stress, and fracture toughness values all decreased with decreasing individual layer thickness.

Wolfe, Douglas Edward

20

Microstructure and mechanical properties of aluminum\\/aluminum-scandium metallic multilayers: Deformation mechanisms at the nanoscale  

Microsoft Academic Search

Multilayer thin film structures with layer dimensions in the nanometer length scale have proven to be some of the strongest synthetic materials ever produced, and in the system studied here, record hardnesses for aluminum-based materials have been observed. This work discusses the fabrication, characterization and mechanical response of a unique system constructed from aluminum and scandium. Thin film deposition techniques

Mark Andrew Phillips

2003-01-01

21

Ion-beam induced transformations in nanoscale multilayers: Evolution of clusters with preferred length scales  

SciTech Connect

Ion-irradiation-induced modifications of a periodic Pt/C multilayer system containing a small amount of Fe have been analyzed by transmission electron microscopy and grazing incidence x-ray diffraction (GIXRD) studies. The multilayer stack with 16 Pt/C layer pairs (period of 4.23 nm) was fabricated on a glass substrate. A 2 MeV Au{sup 2+} ion beam was rastered on the sample to obtain uniformly irradiated strips with fluences from 1x10{sup 14} to 1x10{sup 15} ions/cm{sup 2}. Ion irradiation has been found to cause preferential migration of Fe towards Pt layers [Bera et al., Nucl. Instrum. Methods Phys. Res. B 212, 530 (2003)]. Cross-sectional transmission electron microscopy (XTEM) shows considerable atomic redistribution for irradiation at the highest ion fluence (1x10{sup 15} ions/cm{sup 2}). This structure is composed of small clusters. Phase separation and cluster formation processes are discussed. Periodic multilayers have periodicity only in the direction normal to the multilayer surface. However, Fourier transform (FT) of the XTEM images of the sample irradiated at the highest fluence shows extra off-normal Fourier components of superlattice periodicities arising due to ion irradiation. These extra spots in the FT are due to preferential length scales in intercluster separation in three dimensions. With a proper understanding of this phenomenon it may be possible to fabricate useful three-dimensional self-assembled structures of nanoclusters. Our high resolution transmission electron microscopy and GIXRD results reveal the formation of an FePt alloy. As FePt is a magnetic alloy, our observation raises the possibility of fabrication of ion-beam induced magnetic nanocluster lattices.

Bera, S.; Satpati, B.; Goswami, D. K.; Bhattacharjee, K.; Satyam, P. V.; Dev, B. N. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

2006-04-01

22

In situ x-ray investigation of freestanding nanoscale Cu-Nb multilayers under tensile load.  

SciTech Connect

The yield behavior in a freestanding sputter-deposited Cu/Nb multilayer with 30 nm nominal individual layer thickness has been investigated with in situ synchrotron x-ray diffraction during tensile loading. A pronounced elastic-plastic transition is observed with the fraction of plastically yielded grains increasing gradually with strain. Near synchronous yielding is observed in the Cu and Nb grains. The gradual progression in yield behavior is interpreted in terms of residual stresses, and elastic and plastic anisotropy.

Aydiner, C. C.; Misra, A.; Brown, D. W.; Mara, N. A.; Almer, J. D (X-Ray Science Division); (LANL)

2009-01-01

23

Friction and Wear Properties of WC\\/C Nano-Scale Multilayer Coatings on Technical Surfaces  

Microsoft Academic Search

This article reports on the tribological performance of a WC\\/C multilayer coating with a periodicity WC\\/C = 15\\/5 nm deposited\\u000a on bearing steel substrates. These substrates were initially polished to achieve different RMS roughness values ranging from\\u000a 15 to 900 nm. Tribological tests were performed using a precision reciprocating microtribometer under ambient conditions with\\u000a a steel ball as a counter-sample. The worn sample surfaces

Mikhail Kosinskiy; Syed Imad-Uddin Ahmed; Yonghe Liu; Maik Gubisch; Rostyslav Mastylo; Lothar Spiess; Juergen A. Schaefer

24

Properties of the multi-layer Ti\\/CrN and Ti\\/TiAlN coatings deposited with the PVD technique onto the brass substrate  

Microsoft Academic Search

The paper presents examination results of structure, corrosion resistance, changes of the coating constituents’ concentration and mechanical properties of the CuZn40Pb2 brass coated with the thin Ti\\/CrN and Ti\\/TiAlN 1, 15 and 150-ply multi-layer coatings. It has been demonstrated that the increase of the number of layers in the coating results in the several times greater corrosion resistance of the

L. A. Dobrza?ski; K. Lukaszkowicz; A. Križ

2003-01-01

25

Performance of nano-structured multilayer PVD coating TiAlN\\/VN in dry high speed milling of aerospace aluminium 7010-T7651  

Microsoft Academic Search

A low-friction and wear resistant TiAlN\\/VN multilayer coating with TiAlN\\/VN bilayer thickness 3 nm has been grown by using the combined cathodic arc etching and unbalanced magnetron sputtering deposition on high speed steel tools for dry cutting of aluminium alloys. In this paper, in-lab and industrial high speed milling tests have been performed on an aerospace aluminium alloy 7010-T7651. The

Q. Luo; G. Robinson; M. Pittman; M. Howarth; W.-M. Sim; M. R. Stalley; H. Leitner; R. Ebner; D. Caliskanoglu; P. Eh. Hovsepian

2005-01-01

26

Multiscale modelling and simulation of deformation and strength of nanoscale metallic multilayer systems  

NASA Astrophysics Data System (ADS)

The objective of this research is to investigate the deformation behaviors of two types of NMMs at lower length scales: 1) One dimensional Cu-Ni, Au-Ni nanowires with coherent interfaces and 2) Two dimensional Cu-Nb multilayers with incoherent interfaces. Using molecular dynamics simulations, we investigate the different deformation mechanisms that govern the plastic behavior of the NMMs at different length scales. Based on the fundamental physics of deformation captured by these simulations, we propose models that explain the dependence of strength on layer thickness and identify the regions where the deformation is controlled by either dislocation propagation mechanism or dislocation nucleation mechanism. Chapter 2 investigates the deformation mechanisms of Cu-Ni composite nanowires subjected to uniaxial tensile loading by using MD simulations. The coupled effects of geometry and coherent interface on the twinning and pseudoelastic behavior of nanowires are investigated. It is shown that nanowires exhibit pseudoelastic behaviors when their layer thicknesses are below a critical thickness. We captured similar deformation mechanisms through MD simulations of Au-Ni nano ligaments that are assumed as building blocks of composite Au nanofoams with Ni shells, in chapter 3. Chapter 4 studies the deformation behaviour of Cu-Nb NMMs with incoherent interfaces. Using MD simulations, we investigate the strengthening effect of the weak interfaces interacting with glide dislocations by embedding artificial dislocations inside the layer. In addition, the effects of interfacial discontinuities such as ledges and steps on the strength of the NMMs are investigated. Chapter 5, studies the strengthening effects of the additional second phase particles inside the same Cu-Nb bi-layers. We developed an analytical model to explain the strengthening effect of the precipitates. The theoretical results show a qualitative agreement with the finding of the atomistic simulations. In chapter 6, the operative deformation mechanisms at different length scales for Cu-Nb multilayers under biaxial tensile deformation are determined. We established a unique viscoplastic continuum model able to address the macroscale plastic behaviour of bulk NMMs with layer thickness from few nanometers to hundreds of micrometers. An anisotropic yield function is proposed based on the plastic flow potential obtained from biaxial loading of the NMMs.

Abdolrahim, Niaz

27

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

NASA Astrophysics Data System (ADS)

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

Olac-vaw, Roman

28

Cast iron cutting with nano TiN and multilayer TiN-CrN coated inserts  

NASA Astrophysics Data System (ADS)

During the past decade great success has been achieved in the development of duplex and multilayer multi-functional surface systems. Among these surface systems outstanding properties have nanoscale multilayer coatings. Within the framework of the M3-2S project funded in the 7th European Framework Programme, several nanoscale multilayer coatings have been developed and investigated for experimental and industrial validation. This paper shows the performance of TiN and TiN/CrN nanoscale multilayer coatings on WC cutting inserts when machining GJL250 cast iron. The thin films have been deposited by cathodic arc evaporation in an industrial PVD system. The multilayer deposition characteristic and its properties are shown. The inserts have been investigated in systematic cutting experiments of cast iron bars on a turning machine specifically equipped for force measurements, accompanied by wear determination. Furthermore, equivalent experiments have been carried out on an industrial turning unit. Industrial validation criteria have been applied to assess the comparative performance of the coatings. The choice of the material and the machined parts is driven by an interest in automotive applications. The industrial tests show the need to further optimise the multi-scale modelling approach in order to reduce the lead time of the coating development as well as to improve simulation reliability.

Perucca, M.; Durante, S.; Semmler, U.; Rüger, C.; Fuentes, G. G.; Almandoz, E.

2012-09-01

29

Improvement of wear resistance of hot work steels by PVD coatings deposition  

Microsoft Academic Search

The paper presents results of structure, phase composition, tribological and adhesion investigations of wear resistance PVD coatings TiN, TiN\\/(Ti, Al)N and CrN types deposited in ion plating PVD process onto X37CrMoV5-l type hot work tool steel.The X-ray quantitative phase analysis makes it possible to find out the preferential crystallographic orientation (111) for the monolayer TiN coating and for the multilayer

L. A. Dobrzanski; M. Polok; P. Panjan; S. Bugliosi; M. Adamiak

2004-01-01

30

A new class of high performance PVD coatings for carbide cutting tools  

Microsoft Academic Search

A number of advanced PVD coating designs based on Ti–Al–N–C–B were evaluated in metalcutting. Monolayer PVD TiN, TiAlN, TiB2 and different variants of TiAlN multilayer coatings were deposited on WC-6 wt.% Co hardmetal inserts. The coatings were applied either by cathodic arc processes or a high-ionization magnetron sputtering process. The coated tools were evaluated in milling of ductile and gray

H. G Prengel; P. C Jindal; K. H Wendt; A. T Santhanam; P. L Hegde; R. M Penich

2001-01-01

31

Effects of Processing Parameters on Microstructure and Properties of Nanoscale ZrC/ZrB2 Multilayered Coatings  

NASA Astrophysics Data System (ADS)

ZrC/ZrB2 multilayered coatings with bilayer periods of 3.5-40 nm are synthesized by rf magnetron sputtering. Analyses of x-ray diffraction, scanning electron microscopy and nanoindentation indicate that multilayered coatings possess much higher hardness and greater fracture resistance than monolithic ZrC and ZrB2 coatings. A maximum hardness (41.7 GPa) and a critical fracture load (73.7 mN) are observed in the multilayer with ? = 32 nm deposited at the substrate bias -40 V. Higher residual stress built in the ZrC layer can be released by periodic insertion of ZrB2 into the ZrC layer. A clear multilayered structure with mixed ZrB2(001), ZrB2 (002) and ZrC (111) orientations should be responsible for the enhanced mechanical properties.

Yang, Jin; Zhang, Xue-Hua; Cao, Meng; Wang, Ming-Xia; Liang, Jin-Ling; Li, De-Jun

2006-10-01

32

Nanoscale layer-selective readout of magnetization direction from a magnetic multilayer using a spin-torque oscillator.  

PubMed

Technology for detecting the magnetization direction of nanoscale magnetic material is crucial for realizing high-density magnetic recording devices. Conventionally, a magnetoresistive device is used that changes its resistivity in accordance with the direction of the stray field from an objective magnet. However, when several magnets are near such a device, the superposition of stray fields from all the magnets acts on the sensor, preventing selective recognition of their individual magnetization directions. Here we introduce a novel readout method for detecting the magnetization direction of a nanoscale magnet by use of a spin-torque oscillator (STO). The principles behind this method are dynamic dipolar coupling between an STO and a nanoscale magnet, and detection of ferromagnetic resonance (FMR) of this coupled system from the STO signal. Because the STO couples with a specific magnet by tuning the STO oscillation frequency to match its FMR frequency, this readout method can selectively determine the magnetization direction of the magnet. PMID:24872254

Suto, Hirofumi; Nagasawa, Tazumi; Kudo, Kiwamu; Mizushima, Koichi; Sato, Rie

2014-06-20

33

Nanoscale layer-selective readout of magnetization direction from a magnetic multilayer using a spin-torque oscillator  

NASA Astrophysics Data System (ADS)

Technology for detecting the magnetization direction of nanoscale magnetic material is crucial for realizing high-density magnetic recording devices. Conventionally, a magnetoresistive device is used that changes its resistivity in accordance with the direction of the stray field from an objective magnet. However, when several magnets are near such a device, the superposition of stray fields from all the magnets acts on the sensor, preventing selective recognition of their individual magnetization directions. Here we introduce a novel readout method for detecting the magnetization direction of a nanoscale magnet by use of a spin-torque oscillator (STO). The principles behind this method are dynamic dipolar coupling between an STO and a nanoscale magnet, and detection of ferromagnetic resonance (FMR) of this coupled system from the STO signal. Because the STO couples with a specific magnet by tuning the STO oscillation frequency to match its FMR frequency, this readout method can selectively determine the magnetization direction of the magnet.

Suto, Hirofumi; Nagasawa, Tazumi; Kudo, Kiwamu; Mizushima, Koichi; Sato, Rie

2014-06-01

34

Properties of TiAlCN\\/VCN Nanoscale Multilayer Coatings Deposited by Mixed High-Power Impulse Magnetron Sputtering (HiPIMS) and Unbalanced Magnetron Sputtering Processes—Impact of HiPIMS During Coating  

Microsoft Academic Search

Nanoscale multilayer TiAlCN\\/VCN coating has been deposited by pure unbalanced magnetron sputtering (UBM) and high-power impulse magnetron sputtering (HiPIMS)-UBM techniques. The V+ HiPIMS etching used in both processes has shown excellent adhesion (Lc > 50) of the coating to the substrate. The plasma compositional analysis of V+ HiPIMS etching has shown high metal-to-gas ion ratio with ionization states of V

G. Kamath; A. P. Ehiasarian; P. Eh. Hovsepian

2010-01-01

35

Femtosecond single-shot imaging of nanoscale ferromagnetic order in Co/Pd multilayers using resonant x-ray holography.  

PubMed

We present the first single-shot images of ferromagnetic, nanoscale spin order taken with femtosecond x-ray pulses. X-ray-induced electron and spin dynamics can be outrun with pulses shorter than 80 fs in the investigated fluence regime, and no permanent aftereffects in the samples are observed below a fluence of 25 mJ/cm(2). Employing resonant spatially muliplexed x-ray holography results in a low imaging threshold of 5 mJ/cm(2). Our results open new ways to combine ultrafast laser spectroscopy with sequential snapshot imaging on a single sample, generating a movie of excited state dynamics. PMID:23005013

Wang, Tianhan; Zhu, Diling; Wu, Benny; Graves, Catherine; Schaffert, Stefan; Rander, Torbjörn; Müller, Leonard; Vodungbo, Boris; Baumier, Cédric; Bernstein, David P; Bräuer, Björn; Cros, Vincent; de Jong, Sanne; Delaunay, Renaud; Fognini, Andreas; Kukreja, Roopali; Lee, Sooheyong; López-Flores, Víctor; Mohanty, Jyoti; Pfau, Bastian; Popescu, Horia; Sacchi, Maurizio; Sardinha, Anna B; Sirotti, Fausto; Zeitoun, Philippe; Messerschmidt, Marc; Turner, Joshua J; Schlotter, William F; Hellwig, Olav; Mattana, Richard; Jaouen, Nicolas; Fortuna, Franck; Acremann, Yves; Gutt, Christian; Dürr, Hermann A; Beaurepaire, Eric; Boeglin, Christine; Eisebitt, Stefan; Grübel, Gerhard; Lüning, Jan; Stöhr, Joachim; Scherz, Andreas O

2012-06-29

36

Optical multilayers with an amorphous fluoropolymer  

SciTech Connect

Multilayered coatings were made by physical vapor deposition (PVD) of a perfluorinated amorphous polymer, Teflon AF2400, together with other optical materials. A high reflector at 1064 run was made with ZnS and AF2400. An all-organic 1064-nm reflector was made from AF2400 and polyethylene. Oxide (HfO{sub 2}, SiO{sub 2}) compatibility was also tested. Each multilayer system adhered to itself. The multilayers were influenced by coating stress and unintentional temperature rises during PVD deposition.

Chow, R.; Loomis, G.E.; Lindsey, E.F.

1994-07-01

37

Structure and corrosion properties of PVD Cr-N coatings  

NASA Astrophysics Data System (ADS)

PVD Cr-N coatings produced by physical vapor deposition (PVD) are increasingly used for mechanical and tribological applications in various industrial sectors. These coatings are particularly attractive for their excellent corrosion resistance, which further enhances the lifetime and service quality of coated components. PVD Cr-N coated steels in an aqueous solution are usually corroded by galvanic attack via through-coating ``permeable'' defects (e.g., pores). Therefore, the corrosion performance of Cr-N coated steel is determined by a number of variables of the coating properties and corrosive environment. These variables include: (i) surface continuity and uniformity; (ii) through-coating porosity; (iii) film density and chemical stability; (iv) growth stresses; (v) interfacial and intermediate layers; (vi) coating thickness; (vii) coating composition; and (viii) substrate properties. In this article, PVD Cr-N coatings were prepared, by electron-beam PVD and sputter deposition, with different compositions, thicknesses, and surface roughnesses, by changing the N2 flow rate, applying multilayering techniques and changing the substrate finish prior to coating. The microstructure of such coatings is investigated by various analytical techniques such as glancing angle x-ray diffraction and scanning electron microscopy, which are also correlated with the corrosion performance of the coated steel. Both dc polarization and ac impedance spectroscopy were employed to investigate the corrosion resistance of Cr-N coated steel in a 0.5N NaCl solution. It has been found that the N2 flow rate during reactive deposition strongly determines the microstructure of Cr-N coatings (due to the changing nitrogen content in the film) and can thus affect the corrosion resistance of coated systems. The surface finish of the steel substrate also affects the uniformity and coverage of PVD coatings; grooves and inclusions on the original substrate can raise the susceptibility of coated systems to crevice corrosion. Increased coating thickness can also greatly reduce the incidence of through-coating porosity such that the improvement in corrosion performance of thicker Cr-N coatings is significant.

Liu, C.; Bi, Q.; Ziegele, H.; Leyland, A.; Matthews, A.

2002-05-01

38

Improvement of ‘duplex’ PVD coatings for HSS cutting tools by PFPE (perfluorpolyether ‘Z-DOL’)  

Microsoft Academic Search

A high-speed steel of M2 type was hardened by ‘duplex’ technology (ion nitriding followed by TiN PVD coating). The ‘duplex’ coating was further modified by application of a PFPE (perfluoropolyether Z-DOL) layer at the surface. The tribological parameters of the coating and the changes in composition and fine (atomic level) structural characteristics of the tool surface with a multi-layered coating

G. S. Fox-Rabinovich; A. I. Kovalev; D. L. Wainstein; L. Sh. Shuster; G. K. Dosbaeva

2002-01-01

39

Effect of Modulation Period and N + Beam Bombarding Energy on the growth of Nanoscale ZrB2/AlN Multilayered Coatings Prepared by IBAD  

NASA Astrophysics Data System (ADS)

Monolithic ZrB2, AlN, and ZrB2/AlN multilayered coatings have been synthesized by ion beam assisted deposition at room temperature. Scanning electron microscopy, X-ray diffraction, XP-2 profiler and nano indenter were employed to investigate the influences of modulation period and N + bombarding energy on microstructure and mechanical properties of the coatings. Most of multilayered coatings revealed higher hardness and elastic modulus than the rule-of-mixtures value of monolithic ZrB2 and AlN coatings. N + bombardment at 300 eV resulted in ZrB2/AlN multilayered coating the highest hardness (31.2 GPa) and elastic modulus (372.2 GPa). This hardest multilayer also showed the improved residual stress and fracture resistance. These improved performances are likely a result of more efficient momentum transfer to the deposition particles due to the proper N + bombarding energy.

Sun, Y. D.; Tan, M.; Gong, J.; Liu, M. Y.; Liu, G. Q.; Deng, X. Y.; Li, D. J.

40

Study the Hardness Properties of TiAlN Coatings Prepared by Magnetron Co-sputtering Deposited Nanoscale Multi-layered Structure  

NASA Astrophysics Data System (ADS)

There is increased industrial usage of modern tools used in cutting operations today that are coated with PVD hard coatings based on TiAlN. Coating properties such as thermal stability, hot hardness, and toughness are of interest when designing their functionality in these applications. Ti1-xAlxN films were synthesized by reactive magnetron co--sputtering with different aluminum compositions. XRD, SIMS, Nano indentation techniques were used to analyze these films. Nanoindentation hardness increases with aluminum and started to decrease beyond 81% of aluminum. Continuous Multi-Cycle indentation technique is used to analyze the failure mode of the film with highest hardness and structural properties and on coating response to high temperature oxidation is presented.

Sahu, Dilip Kumar; Agrawal, Sadhana; Saji, Janita

2011-11-01

41

The effects of rapid thermal annealing on the electrical, optical, and structural properties of Nb:TiO2 multilayer electrodes with an inserted nanoscale Ag layer for organic solar cells  

NASA Astrophysics Data System (ADS)

We investigated the effects of rapid thermal annealing (RTA) on the electrical, optical, structural, interfacial, and surface properties of Nb:TiO2 (NTO)-Ag-NTO multilayer electrodes inserting a nanoscale Ag layer for application in organic solar cells (OSCs). Up to an annealing temperature of 500 °C, the resistivity and optical transmittance of the NTO-Ag-NTO electrodes were stably maintained due to the absence of Ag outdiffusion. The effective activation of the Nb in the NTO layer led to a slight decrease in the resistivity and an increase in the band gap caused by the Burstein-Moss effect. However, increasing the RTA temperature above 600 °C resulted in degradation of the NTO-Ag-NTO multilayer electrode due to severe Ag diffusion. Based on the synchrotron x-ray scattering and x-ray photoelectron spectroscopy analyses results, the electrical properties of the NTO-Ag-NTO electrodes are correlated with the microstructure and interfacial diffusion of each layer. In addition, it was found that the performance of the OSC was critically dependent on the RTA temperature of the NTO-Ag-NTO electrodes even though the as-deposited NTO-Ag-NTO electrode had a fairly low resistivity. This indicates that the activation of Nb dopants in the top NTO layer plays an important role in the extraction of carriers from the organic layer to the anode (NTO-Ag-NTO) electrode.

Park, Jun-Hyuk; Choi, Yoon-Young; Kim, Han-Ki; Lee, Hyun Hwi; Na, Seok-In

2010-10-01

42

Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings  

NASA Technical Reports Server (NTRS)

In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (< 10 microns) single layers to be deposited and multilayer coatings of less than 100 microns to be generated with the flexibility to tailor microstructures by changing processing conditions. Coatings of yttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coated superalloy substrates using the PS-PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

Harder, Bryan J.; Zhu, Dongming

2011-01-01

43

The effect of (Ti+Al):V ratio on the structure and oxidation behaviour of TiAlN\\/VN nano-scale multilayer coatings  

Microsoft Academic Search

Nano-scaled multilayered TiAlN\\/VN coatings have been grown on stainless steel and M2 high speed steel substrates at UB=?85 V in an industrial, four target, Hauzer HTC 1000 coater using combined cathodic steered arc etching\\/unbalanced magnetron sputtering. X-ray diffraction (XRD) has been used to investigate the effects of process parameters (Target Power) on texture evolution (using texture parameter T*), development of

D. B Lewis; S Creasey; Z Zhou; J. J Forsyth; A. P Ehiasarian; P. Eh Hovsepian; Q Luo; W. M Rainforth; W.-D Münz

2004-01-01

44

Tribological properties of unbalanced magnetron sputtered nano-scale multilayer coatings TiAlN\\/VN and TiAlCrYN deposited on plasma nitrided steels  

Microsoft Academic Search

Unbalanced magnetron sputtered multilayer coatings TiAlN\\/VN and TiAlCrYN grown on pulse plasma nitriding pre-treated low alloy steel P20 have been characterised by using X-ray diffraction (XRD), scanning electron microscope (SEM), micro-indentation, scratch and pin-on-disc wear tests. A 160-?m-thick nitrided case was formed on the steel surface containing a pure Fe3N and Fe4N compound layer and showing hardness up to 8.5

Q. Luo; P. Eh. Hovsepian; D. B. Lewis; W.-D. Münz; Y. N. Kok; J. Cockrem; M. Bolton; A. Farinotti

2005-01-01

45

An electroplaters view of PVD processing  

SciTech Connect

This paper provides a comparison of electroplating and PVD processing from the viewpoint of a person who has been involved with the electroplating industry for the past 42 years and PVD processing for the past 12 years. During this recent 12 year period he has served as a manager of groups involved with both electroplating and PVD operations so he has had the chance to closely observe both technologies. After a brief description of each of the coating processes, comparisons are provided with respect to coating choices, deposition rates, properties, adhesion, costs and waste minimization. In addition, examples are provided to demonstrate that by combining the deposition technologies synergism can often be obtained. The conclusion drawn from these comparisons is that both deposition technologies are viable processes and each has its own particular benefits/drawbacks.

Dini, J.W.

1992-01-01

46

Comparison of the PVD coatings deposited onto hot work tool steel and brass substrates  

Microsoft Academic Search

Purpose: The aim of the research is the investigation of the structure and mechanical properties of monolayers CrN, TiN and multilayers TiN\\/TiAlN and Ti\\/TiAlN coatings deposited by PVD techniques onto the substrate from the X37CrMoV5-1 steel and CuZn40Pb2 brass. Design\\/methodology\\/approach: The microhardness tests were made on the dynamic ultra-microhardness tester. Tests of the coatings' adhesion to the substrate material were

M. Polok-Rubiniec; K. Lukaszkowicz; L. A. Dobrza?ski; M. Adamiak

47

PVD TBC experience on GE aircraft engines  

NASA Technical Reports Server (NTRS)

The higher performance levels of modern gas turbine engines present significant challenges in the reliability of materials in the turbine. The increased engine temperatures required to achieve the higher performance levels reduce the strength of the materials used in the turbine sections of the engine. Various forms of thermal barrier coatings (TBC's) have been used for many years to increase the reliability of gas turbine engine components. Recent experience with the physical vapor deposition (PVD) process using ceramic material has demonstrated success in extending the service life of turbine blades and nozzles. Engine test results of turbine components with a 125 micron (0.005 in) PVD TBC have demonstrated component operating temperatures of 56-83 C (100-150 F) lower than non-PVD TBC components. Engine testing has also revealed the TBC is susceptible to high angle particle impact damage. Sand particles and other engine debris impact the TBC surface at the leading edge of airfoils and fracture the PVD columns. As the impacting continues, the TBC erodes away in local areas. Analysis of the eroded areas has shown a slight increase in temperature over a fully coated area, however a significant temperature reduction was realized over an airfoil without TBC.

Maricocchi, Antonio; Bartz, Andi; Wortman, David

1995-01-01

48

Low friction PVD titanium–carbon coatings  

Microsoft Academic Search

PVD coatings based on diamond like carbon (DLC) can suffer from poor toughness if deposited using hydrocarbon gas. Incorporation of hydrogen is known to cause high compressive residual stresses and voids. Both these phenomena act detrimental on the coating fracture toughness. Thus, one way to improve the coating toughness, would be to use other deposition techniques and not include hydrocarbon

U Wiklund; M Larsson

2000-01-01

49

Generation and performance of localised surface plasmons utilising nano-scale structured multi-layered thin films deposited upon D-shaped optical fiber  

NASA Astrophysics Data System (ADS)

A new generation of surface plasmonic optical fibre sensors is fabricated using multiple coatings deposited on a lapped section of a single mode fibre. Post-deposition UV laser irradiation using a phase mask produces a nano-scaled surface relief grating structure, resembling nano-wires. The overall length of the individual corrugations is approximately 14 ?m with an average full width half maximum of 100 nm. Evidence is presented to show that these surface structures result from material compaction created by the silicon dioxide and germanium layers in the multi-layered coating and the surface topology is capable of supporting localised surface plasmons. The coating compaction induces a strain gradient into the D-shaped optical fibre that generates an asymmetric periodic refractive index profile which enhances the coupling of the light from the core of the fibre to plasmons on the surface of the coating. Experimental data are presented that show changes in spectral characteristics after UV processing and that the performance of the sensors increases from that of their pre-UV irradiation state. The enhanced performance is illustrated with regards to change in external refractive index and demonstrates high spectral sensitivities in gaseous and aqueous index regimes ranging up to 4000 nm/RIU for wavelength and 800 dB/RIU for intensity. The devices generate surface plasmons over a very large wavelength range, (visible to 2 ?m) depending on the polarization state of the illuminating light.

Allsop, T.; Neal, R.; Mou, C.; Dvorak, M.; Rozhin, A.; Kalli, K.; Webb, D. J.

2013-09-01

50

On the structure and oxidation mechanisms in nanoscale hard coatings  

NASA Astrophysics Data System (ADS)

Thin-film structures consisting of alternating nanoscale multilayers show substantial hardness increases compared with monolithic coatings of the constituent materials. Coatings, such as TiAlN/VN are deposited using PVD with individual coating bi-layer thickness of ~3nm. Since TiAlN and VN are isostructural and mutually soluble, mixing of the two layers during deposition is expected, which will inevitably affect properties. Energy filtered TEM using a field emission gun source allowed important information on layer structure, but failed to reveal details <1nm. Spherical aberration corrected scanning transmission electron microscopy (STEM) allowed the composition of individual atomic columns to be probed, which yielded a good match between experiment and numerical models of the layer mixing. For high speed machining operations, the oxidation behaviour of coatings becomes an important consideration. Static oxidation of TiAlN/VN films was studied in the range 550-700oC, and characterised by high temperature in-situ XRD and STEM/EDX/EELS of selected surface cross-sections. Oxidation of the TiAlN/VN coating started at >=550°C with the VN being the first component to oxidise. At temperatures >600°C, a duplex oxide structure was formed, with several phases observed, including V2O5, TiO2 and AlVO4, with V2O5 being the dominant oxide at the outer layer at 638°C. These coatings exhibit low friction in dry sliding which is believed to arise from the inherently low friction of V2O5. Focused ion beam studies of wear tests at 630°C confirmed that the contact surface comprised small (~50nm), equiaxed and largely agglomerated V2O5 crystals, confirming the hypothesis.

Rainforth, W. Mark; Zhou, Z.

2006-02-01

51

EDITORIAL: Nanoscale metrology Nanoscale metrology  

Microsoft Academic Search

This special issue of Measurement Science and Technology presents selected contributions from the NanoScale 2010 seminar held in Brno, Czech Republic. It was the 5th Seminar on Nanoscale Calibration Standards and Methods and the 9th Seminar on Quantitative Microscopy (the first being held in 1995). The seminar was jointly organized with the Czech Metrology Institute (CMI) and the Nanometrology Group

P. Klapetek; L. Koenders

2011-01-01

52

Erosion of gadolinia doped EB-PVD TBCs  

Microsoft Academic Search

Gadolinia additions have been shown to significantly reduce the thermal conductivity of EB-PVD TBCs. The aim of this paper is to further the understanding on the effects of dopants on the erosion resistance of EB-PVD TBCs by studying the effects of 2 mol% Gd2O3 additions on the room and high temperature erosion resistance of as received and aged EB-PVD TBCs. Previously

R. J. L. Steenbakker; R. G. Wellman; J. R. Nicholls

2006-01-01

53

Ordered metal nanotube arrays fabricated by PVD.  

PubMed

In this work we report a simple method to fabricate ordered arrays of metal nanotubes. This method is based on the deposition of a metal by PVD onto an anodized aluminum oxide (AAO) template. The dimensions of the synthesized nanotubes depend both on the AAO template and on the deposited metal. In fact, it is observed that the aspect ratios of the nanotubes clearly depend significantly on the metal, ranging from 0.6 (Fe) to at least 3 (Zr). PMID:20352765

Marquez, F; Morant, C; Campo, T; Sanz, J M; Elizalde, E

2010-02-01

54

Controlling light with plasmonic multilayers  

NASA Astrophysics Data System (ADS)

Recent years have seen a new wave of interest in layered media - namely, plasmonic multilayers - in several emerging applications ranging from transparent metals to hyperbolic metamaterials. In this paper, we review the optical properties of such subwavelength metal-dielectric multilayered metamaterials and describe their use for light manipulation at the nanoscale. While demonstrating the recently emphasized hallmark effect of hyperbolic dispersion, we put special emphasis to the comparison between multilayered hyperbolic metamaterials and more broadly defined plasmonic-multilayer metamaterials A number of fundamental electromagnetic effects unique to the latter are identified and demonstrated. Examples include the evolution of isofrequency contour shape from elliptical to hyperbolic, all-angle negative refraction, and nonlocality-induced optical birefringence. Analysis of the underlying physical causes, which are spatial dispersion and optical nonlocality, is also reviewed. These recent results are extremely promising for a number of applications ranging from nanolithography to optical cloaking.

Orlov, Alexey A.; Zhukovsky, Sergei V.; Iorsh, Ivan V.; Belov, Pavel A.

2014-06-01

55

Nanophotonics: Nanoscale Optical Interactions  

Microsoft Academic Search

Nanophotonics defined as nanoscale optical science and technology is a new frontier, which includes nanoscale confinement of radiation, nanoscale confinement of matter, and nanoscale photophysical or photochemical transformation. Selected examples of our research work in each of these areas are presented here. Nonlinear optical interactions involving nanoscale confinement of radiation is both theoretically and experimentally studied using a near-field geometry.

Sung-Jae Chung; Kyoung-Soo Kim; Tzu-Chau Lin; Yuzhen Shen; Przemyslaw Markowicz; Guang S. He; Paras N. Prasad

2002-01-01

56

Performance evaluation of PVdF gel polymer electrolytes  

Microsoft Academic Search

A series of gel polymer electrolytes containing PVdF as homo polymer, a mixture of 1:1 Ethylene Carbonate (EC) : Propylene\\u000a Carbonate (PC) as plasticizer and lithium-bistrifluoromethane sulphone imide [imide — LiN (CF3SO2)2] has been developed. Amounts of polymer (PVdF), plasticizer and the imide lithium salt have been varied as a function of\\u000a their weight ratio composition in this regard. Dimensionally

P. Periasamy; K. Tatsumi; N. Kalaiselvi; M. Shikano; T. Fiyieda; Y. Saito; T. Sakai; M. Mizukata; A. Kajinami; S. Deki

2002-01-01

57

Vapor Phase Deposition Using Plasma Spray-PVD  

NASA Astrophysics Data System (ADS)

Plasma spray—physical vapor deposition (PS-PVD) is a low pressure plasma spray technology to deposit coatings out of the vapor phase. PS-PVD is a part of the family of new hybrid processes recently developed by Sulzer Metco AG (Switzerland) on the basis of the well-established low pressure plasma spraying (LPPS) technology. Included in this new process family are plasma spray—chemical vapor deposition (PS-CVD) and plasma spray—thin film (PS-TF) processes. In comparison to conventional vacuum plasma spraying and LPPS, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and EB-PVD coatings. This paper reports on the progress made at Sulzer Metco to develop functional coatings build up from vapor phase of oxide ceramics and metals.

von Niessen, K.; Gindrat, M.; Refke, A.

2010-01-01

58

Electrodeposited multilayer films with giant magnetoresistance ( GMR): Progress and problems  

Microsoft Academic Search

The giant magnetoresistance (GMR) effect was discovered in 1988 in nanoscale metallic ferromagnetic\\/non-magnetic (FM\\/NM) multilayers. By now, devices based on this phenomenon have been widely commercialized which use multilayered structures manufactured via physical deposition (PD) methods, mainly sputtering. It was shown in the early 1990s that electrodeposition (ED) is also capable of producing multilayered magnetic nanostructures exhibiting a significant GMR

I. Bakonyi; L. Péter

2010-01-01

59

Nanoscale Proteomics  

SciTech Connect

This paper describes efforts to develop a liquid chromatography (LC)/mass spectrometry (MS) technology for ultra-sensitive proteomics studies, i.e. nanoscale proteomics. The approach combines high-efficiency nano-scale LC with advanced MS, including high sensitivity and high resolution Fourier transform ion cyclotron resonance (FTICR) MS, to perform both single-stage MS and tandem MS (MS/MS) proteomic analyses. The technology developed enables large-scale protein identification from nanogram size proteomic samples and characterization of more abundant proteins from sub-picogram size complex samples. Protein identification in such studies using MS is feasible from <75 zeptomole of a protein, and the average proteome measurement throughput is >200 proteins/h and ~3 h/sample. Higher throughput (>1000 proteins/h) and more sensitive detection limits can be obtained using a “accurate mass and time” tag approach developed at our laboratory. These capabilities lay the foundation for studies from single or limited numbers of cells.

Shen, Yufeng; Tolic, Nikola; Masselon, Christophe D.; Pasa-Tolic, Liljiana; Camp, David G.; Anderson, Gordon A.; Smith, Richard D.; Lipton, Mary S.

2004-02-01

60

Nanoscale proteomics.  

PubMed

Efforts to develop a liquid chromatography (LC)/mass spectrometry (MS) technology for ultra-sensitive proteomics studies (i.e., nanoscale proteomics) are described. The approach combines high-efficiency nanoscale LC (separation peak capacity of approximately 10(3); 15-microm-i.d. packed capillaries with flow rates of 20 nL min(-1), the optimal separation linear velocity) with advanced MS, including high-sensitivity and high-resolution Fourier transform ion cyclotron resonance MS, to perform both single-stage MS and tandem MS (MS/MS) proteomic analyses. The technology enables broad protein identification from nanogram-size proteomics samples and allows the characterization of more abundant proteins from sub-picogram-size samples. Protein identification in such studies using MS is demonstrated from <75 zeptomole of a protein. The average proteome measurement throughput is approximately 50 proteins h(-1) using MS/MS during separations, presently requiring approximately 3 h sample(-1). Greater throughput (approximately 300 proteins h(-1)) and improved detection limits providing more comprehensive proteome coverage can be obtained by using the "accurate mass and time" tag approach developed in our laboratory. This approach provides a dynamic range of at least 10(6) for protein relative abundances and an improved basis for quantitation. These capabilities lay the foundation for studies from single or limited numbers of cells. PMID:14647945

Shen, Y; Toli?, N; Masselon, C; Pasa-Toli?, L; Camp, D G; Lipton, M S; Anderson, G A; Smith, R D

2004-02-01

61

Experiences from scratch testing of tribological PVD coatings  

Microsoft Academic Search

The use of PVD coatings in tribological applications becomes more and more widespread. Thus also the need to fully understand the relationships between the intrinsic properties of the coating, the properties of the coating\\/substrate composite and the tribological performance of the composite in different tribological systems becomes increasingly pressing. One of the tools available for tribological characterization of coatings and

Per Nledengvist; Sture Hogmark

1997-01-01

62

Properties of Pd nanocrystals prepared by PVD method  

Microsoft Academic Search

Pd nanocrystals obtained by the physical vacuum deposition (PVD) method were studied by X-ray diffraction, transmission electron microsocpy (TEM), atomic force microsocpy (AFM) and optical absorption methods. These Pd fcc nanocrystals are embedded in carbonaceous matrix. The object of study was the structure of Pd nanocrystals and interaction between Pd and carbon matrix interface. In the research a metal-organic crystalline

E. Czerwosz; R. Diduszko; P. D?u?ewski; J. K?czkowska; M. Koz?owski; J. Rymarczyk; M. Sucha?ska

2007-01-01

63

Antimicrobial titanium\\/silver PVD coatings on titanium  

Microsoft Academic Search

BACKGROUND: Biofilm formation and deep infection of endoprostheses is a recurrent complication in implant surgery. Post-operative infections may be overcome by adjusting antimicrobial properties of the implant surface prior to implantation. In this work we described the development of an antimicrobial titanium\\/silver hard coating via the physical vapor deposition (PVD) process. METHODS: Coatings with a thickness of approximately 2 ?m

Andrea Ewald; Susanne K Glückermann; Roger Thull; Uwe Gbureck

2006-01-01

64

Some observations on erosion mechanisms of EB PVD TBCS  

Microsoft Academic Search

Following the successful application of electron beam (EB) physical vapour deposition (PVD) thermal barrier coatings (TBCs) to moving parts of turbine engines, the erosion resistance of these coatings has been of interest among researchers. However, although there are a number of papers on the erosion rate of these coatings, little has been reported on their erosion mechanism. This paper provides

R. G Wellman; J. R Nicholls

2000-01-01

65

Integrated arc suppression unit for defect reduction in PVD applications  

Microsoft Academic Search

Arcing between the target and plasma during PVD deposition causes substantial damage to the target and splats and other contamination on the deposited films. Arc-related damages and defects are frequently encountered in microelectronics manufacturing and contributes largely to reduced wafer yields. Arcing is caused largely by the charge buildup at the contaminated sites on the target surface that contains either

Xiangbing Li; Murali K. Narasimhan; Vikram Pavate; David Loo; Steve Rosenblum; Larry Trubell; Richard Scholl; Scott Seamons; Chris Hagerty; Sesh Ramaswami

1997-01-01

66

Microstructures and mechanical properties of sputtered Cu\\/Cr multilayers  

Microsoft Academic Search

The microstructures and mechanical properties of Cu\\/Cr multilayers prepared by sputtering onto {l_brace}100{r_brace} Si substrates at room temperature are presented. The films exhibit columnar grain microstructures with nanoscale grain sizes. The interfaces are planar and abrupt with no intermixing, as expected from the phase diagram. The multilayers tend to adopt a Kurdjumov-Sachs (KS) orientation relationship: {l_brace}110{r_brace}Cr \\/\\/ {l_brace}111{r_brace}Cu, <111>Cr \\/\\/

A. Misra; H. Kung; T. E. Mitchell; T. R. Jervis; M. Nastasi

1998-01-01

67

The fretting corrosion resistance of PVD surface-modified orthopedic implant alloys.  

PubMed

The objective of this study was to evaluate the fretting corrosion resistance of both modified and unmodified Ti6Al4V flats fretted against CoCr-alloy spheres in a buffered Hank's solution at 37 degrees C using an original fretting apparatus. A physical vapor deposition (PVD) cathodic arc evaporation technique was used to deposit 3-4 microm thick titanium nitride (TiN), zirconium nitride (ZrN), or amorphous carbon (AC) coatings onto the Ti6Al4V substrates. The fretting behavior of the nitride films (TiN and ZrN) was characterized by the absence of surface damage and the deposition of a Cr-rich oxide transferred from the CoCr-alloy spheres to the modified surfaces. This oxide led to a slight increase in surface roughness. Three of the six multilayered AC coatings tested exhibited extensive fretting damage and generated large, deep, wear scars. Cohesive failure of the AC coating was observed in the low contact stress areas of the fretting scars. The remaining AC-coated specimens experienced only slight polishing wear. The reason for the different behavior within the AC-coated specimens is not clear at the present time. The unmodified Ti6Al4V surfaces experienced severe surface damage consistent with the adhesive galling mechanism to which these alloys are susceptible. PMID:11241334

Hendry, J A; Pilliar, R M

2001-01-01

68

Ionic Conductivity of Membranes Based on PVdF-HFP  

NASA Astrophysics Data System (ADS)

Membranes based on PVdF-HFP have been prepared by solution-casting methode. Lithium perchlorate (LiClO4) and lithium trifluoromethane sulfonate (LiCF3SO3) were used as lithium salts, and ethylene carbonate and a mixture of ethylene and propylene carbonate (1:1 wt. %) as plasticizers. The ionic conductivity was determined by means of impedance spectroscopy. The Nyquist plot was fitted with a general equivalent circuit. The ionic conductivity increases to plastificizer content. The membrane consisting of 50 w% PVdF-HFP, 35 w% PC+EC and 15 w% LiCF3SO3 has the highest conductivity with a value of 6.892×10-3 S/cm at room temperature.

Garcia-Bernabé, A.; Gil-Agustí, M.; González-Gutiérrez, J. P.; Quijano-López, A.

2010-06-01

69

Improved Corrosion Resistance of Nanostructured Copper Deposited by Eb-Pvd in Acidic Media  

NASA Astrophysics Data System (ADS)

Electron Beam-Physical Vapor Deposition (EB-PVD) is being used in coating component for many applications such as electronic industry for producing nanostructures and ICs coatings. In this work, nanostructured copper was deposited on glass using EB-PVD technique. Surface and elemental characteristics of EB-PVD coatings investigated and evidenced corrosion resistance of nanostructured coatings produced by this technique are higher than Cu sheet in chloride media.

Saremi, M.; Yeganeh, M.

70

Rapid manufacturing of rhenium components using EB-PVD  

Microsoft Academic Search

Purpose – The purpose of this paper is to provide insights for understanding the relationship between rapid manufacturing process for rhenium components in jet nozzle fabrication using electron beam-physical vapor deposition (EB-PVD). Specifically, to develop a methodology to characterize and improve this new process through motion planning for maintaining uniformity in the deposition thickness. Design\\/methodology\\/approach – This research first identifies

Vittal V. Prabhu; Indraneel V. Fuke; Sohyung Cho; Jogender Singh

2005-01-01

71

Studies on PVdF-based gel polymer electrolytes  

Microsoft Academic Search

A complex of polymer, plasticizer and lithium salts can be used as a solid gel polymer electrolyte in lightweight and rechargeable lithium batteries. Considerable research has been directed towards the development of a gel polymer with high conductivity at room temperature. In this work, a gel polymer electrolyte using polyvinylidene fluoride (PVdF)-1000 (KF), a plasticizer of 1:1 ethylene carbonate (EC)

P. Periasamy; K. Tatsumi; M. Shikano; T. Fujieda; Y. Saito; T. Sakai; M. Mizuhata; A. Kajinami; S. Deki

2000-01-01

72

Ionic Conductivity of Membranes Based on PVdF-HFP  

Microsoft Academic Search

Membranes based on PVdF-HFP have been prepared by solution-casting methode. Lithium perchlorate (LiClO4) and lithium trifluoromethane sulfonate (LiCF3SO3) were used as lithium salts, and ethylene carbonate and a mixture of ethylene and propylene carbonate (1:1 wt. %) as plasticizers. The ionic conductivity was determined by means of impedance spectroscopy. The Nyquist plot was fitted with a general equivalent circuit. The

A. Garcia-Bernabe´; M. Gil-Agusti´; J. P. Gonza´lez-Gutie´rrez; A. Quijano-Lo´pez

2010-01-01

73

Thermal shock behavior of EB-PVD thermal barrier coatings  

Microsoft Academic Search

Yttria partially stabilized zirconia ceramic top coat was deposited on a sputtered NiCrAlY bond coat by electron beam physical vapor deposition (EB-PVD) and the thermal shock behavior was studied at different temperatures. The results showed that the columnar structure of the ceramic top coat enhanced the ability of the TBC to resist thermal shock. However, the thermal shock life of

Meiheng Li; Xiaofeng Sun; Wangyu Hu; Hengrong Guan

2007-01-01

74

Excitons in nanoscale systems  

Microsoft Academic Search

Nanoscale systems are forecast to be a means of integrating desirable attributes of molecular and bulk regimes into easily processed materials. Notable examples include plastic light-emitting devices and organic solar cells, the operation of which hinge on the formation of electronic excited states, excitons, in complex nanostructured materials. The spectroscopy of nanoscale materials reveals details of their collective excited states,

Gregory D. Scholes; Garry Rumbles

2006-01-01

75

Evolution of self-organization in nano-structured PVD coatings under extreme tribological conditions  

NASA Astrophysics Data System (ADS)

The evolution of the self-organization process where dissipative structures are formed under the extreme frictional conditions associated with high performance dry machining of hardened steels has been studied in detail. The emphasis was on the progressive studies of surface transformations within multilayer and monolayer TiAlCrSiYN-based PVD coatings during the running-in stage of wear when self-organization process occurs. The coating layer was characterized by high resolution electron energy-loss spectroscopy (HREELS). It is shown that the nano-multilayer coating possesses higher non-equilibrium structure in comparison to the monolayer. Comprehensive studies of the tribo-films (dissipative structures) formed on the friction surface were made using a number of advanced surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES). The data obtained for the tribo-films was combined with the detailed TEM studies of the structural and phase transformations within the underlying coating layer. This data was related to the micro-mechanical characteristics of the coating layer and its wear resistance. It was demonstrated that the evolution of the self-organization process is strongly controlled by the characteristics of the tribo-films formed at different stages of the wear process. Within running-in stage (after length of cut of 15 m) fully protective mullite tribo-films predominantly form on the surface of nano-multilayer coating, establishing a functional hierarchy within the layer of tribo-films. This reduces entropy production during friction and leads to significant surface damage reduction and wear rate stabilization. In contrast, in a monolayer coating with a lower structural complexity, a variety of protective and non-protective tribo-films form during the running-in stage, which cannot fully protect the surface. Therefore the wear rate on the monolayer is not stabilized and its wear resistance is lower. The results obtained show that it is possible to control tribo-films evolution during self-organization by means of increase in structural complexity and the non-equilibrium state of the surface engineered layer with simultaneous tuning of its integrative behaviour.

Fox-Rabinovich, G.; Kovalev, A.; Aguirre, M. H.; Yamamoto, K.; Veldhuis, S.; Gershman, I.; Rashkovskiy, A.; Endrino, J. L.; Beake, B.; Dosbaeva, G.; Wainstein, D.; Yuan, Junifeng; Bunting, J. W.

2014-04-01

76

Novel porous separator based on PVdF and PE non-woven matrix for rechargeable lithium batteries  

Microsoft Academic Search

The novel porous separator based on PVdF (poly(vinylidene fluoride)) and a PE (polyethylene) non-woven matrix is prepared by coating PVdF\\/NMP solution on the matrix (NMP: N-methyl-2-pyrrolidone). The pore structure is generated in the PVdF region by phase inversion of the polymer solution. The PE non-woven matrix imparts mechanical strength and a thermal shut-down property to the separator, while the PVdF

Yong Min Lee; Jun-Woo Kim; Nam-Soon Choi; Je An Lee; Wan-Ho Seol; Jung-Ki Park

2005-01-01

77

Nanoscale Power and Memory Unit Design for Nanoscale Sensor Systems  

Microsoft Academic Search

Nanoscale sensor systems require the development of nanometer scale integrated circuits and components. Due to limits in device physics, new components must be developed to operate at the nanoscale level. As part of this effort, the authors have constructed nanoscale battery arrays that can implement power supply units for nanoscale sensor systems. In addition, the authors are currently developing a

Theodore W. Manikas; Dale Teeters

2007-01-01

78

A Monte Carlo model for predicting the erosion rate of EB PVD TBCs  

Microsoft Academic Search

Since the introduction of electron beam (EB) physical vapour deposition (PVD) thermal barrier coatings (TBCs) and their application to moving components in the hot gas stream, erosion has become a prime concern. EB PVD TBCs, due to their unique columnar microstructure are far more strain tolerant than their plasma sprayed (PS) counter parts and can thus be used under more

R. G Wellman; J. R Nicholls

2004-01-01

79

INCREASING THE LIFETIME OF ALUMINIUM AND MAGNESIUM PRESSURE DIE CASTING MOULDS BY ARC ION PLATING PVD COATINGS  

Microsoft Academic Search

Nowadays PVD coatings are wide-spread and state of the art in the machining industry. Due to their properties, like high hardness, corr osion resistance and high temperature stability, PVD coatings have achieved large industrial applications. In this paper, PVD coatings are used for extending the lifetime of a pressure casting mould. A main factor influencing the lifetime of a die

E. Lugscheider; K. Bobzin; T. Hornig; M. Maes

80

Nanoscale construction with DNA  

NASA Astrophysics Data System (ADS)

The programmability of DNA makes it an attractive material for constructing intricate nanoscale shapes. One method for creating these structures is DNA origami, in which a multiple-kilobase single-stranded ``scaffold'' is folded into a custom nanoscale shape by interacting with hundreds of short oligonucleotide ``staple'' strands. I will talk about our efforts to realize demand-meeting applications of this method, including our recent development of nanoscale devices to mimic cell-signaling stimulation carried out by our own immune systems.

Douglas, Shawn

2013-03-01

81

Nanoscale Physics Inquiry Activities  

NASA Astrophysics Data System (ADS)

A series of inquiry activities have been developed through the Nano Education and Outreach (NEO) Program, a graduate student development program offered through the Nanoscale Informal Science Education (NISE) Network at the Exploratorium in San Francisco, to introduce students to the field of nanoscale physics and nanotechnology. Geared for middle school through high school students, these inquiry activities investigate the physical and chemical properties of nanoscale materials and advances and research in nanotechnology. A series of new inquiry activities will be presented along with an overview of the NEO program.

Johnsen, Jill N.

2006-12-01

82

Studies on PVdF-based gel polymer electrolytes  

NASA Astrophysics Data System (ADS)

A complex of polymer, plasticizer and lithium salts can be used as a solid gel polymer electrolyte in lightweight and rechargeable lithium batteries. Considerable research has been directed towards the development of a gel polymer with high conductivity at room temperature. In this work, a gel polymer electrolyte using polyvinylidene fluoride (PVdF)-1000 (KF), a plasticizer of 1:1 ethylene carbonate (EC) and propylene carbonate (PC), and LiBF 4 salt is optimized. Gel electrolytes have high ionic conductivity, good mechanical stability, a wide electrochemical stable window, and a stable lithium interface. The results of preliminary charge-discharge of cells are discussed in detail.

Periasamy, P.; Tatsumi, K.; Shikano, M.; Fujieda, T.; Saito, Y.; Sakai, T.; Mizuhata, M.; Kajinami, A.; Deki, S.

83

Indentation Analysis of a Multi-Layered Hollow Cylinder for the Measurement of Interfacial Toughness in TBC Systems  

Microsoft Academic Search

Summary This paper addresses the mechanics of indentation-induced delamination of a coating on a multi-layered hollow cylinder, for application to toughness testing of thermal barrier coating (TBC) systems. An electron-beam physical vapor depo- sition (EB-PVD) TBC system has been analyzed through a contact finite element model usingastandardconical indenterimpressed verticallyon thetop ofthecylin- der. Two cylinder sizes used in thermal-mechanical fatigue tests

Q. Ma; J. L. Beuth; G. H. Meier; F. S. Pettit

2008-01-01

84

Nanoscale Microelectronic Circuit Development.  

National Technical Information Service (NTIS)

The purpose of this program was to stimulate research in nanoscale microelectronic circuit development and to increase the domestic microelectronics workforce by providing research and educational opportunities to U.S. citizens, both undergraduates and gr...

J. A. Ringo

2011-01-01

85

The short-term cycling properties of Na\\/PVdF\\/S battery at ambient temperature  

Microsoft Academic Search

The Na\\/PVdF\\/S cells were composed of solid sodium, sulfur, and polyvinylidene fluoride–hexafluoropropene (PVdF) gel polymer\\u000a electrolyte. The PVdF polymer electrolyte was prepared form tetraglyme plasticizer and NaCF3SO3 salt, and its electrochemical properties were studied using CV and impedance analysis. The interfacial resistance between\\u000a sodium and polymer electrolyte increase with storage time, which might be associated with passivation layer. Solid-state sodium\\/sulfur

Jong-Seon Kim; Hyo-Jun Ahn; Ic-Pyo Kim; Ki-Won Kim; Jou-Hyeon Ahn; Cheol-Wan Park; Ho-Suk Ryu

2008-01-01

86

Characterization of Mo/Si multilayer growth on stepped topographies  

SciTech Connect

Mo/Si multilayer mirrors with nanoscale bilayer thicknesses have been deposited on stepped substrate topographies, using various deposition angles. The multilayer morphology at the stepedge region was studied by cross section transmission electron microscopy. A transition from a continuous- to columnar layer morphology is observed near the step-edge, as a function of the local angle of incidence of the deposition flux. Taking into account the corresponding kinetics and anisotropy in layer growth, a continuum model has been developed to give a detailed description of the height profiles of the individual continuous layers. Complementary optical characterization of the multilayer system using a microscope operating in the extreme ultraviolet wavelength range, revealed that the influence of the step-edge on the planar multilayer structure is restricted to a region within 300 nm from the step-edge.

Boogaard, A. J. R. vcan den; Louis, E.; Zoethout, E.; Goldberg, K. A.; Bijkerk, F.

2011-08-31

87

Corrosion properties of nitride, oxide and multilayer coatings on stainless steel and titanium-based substrates  

NASA Astrophysics Data System (ADS)

A comparative analysis is made of the parameters of oxide, nitride and multilayer coatings, such as TiN, deposited by means of Arc-PVD, oxide Al2O3 films deposited by magnetron sputtering (MS), and of multilayer TiN/Al2O3 on stainless steel (1H18N9) and a titanium-based material (Ti4Al6V). The corrosion examinations of anodic polarization by potentiodynamic method, Tafel and Stern curves and also impedance method at NaCl and SBF solutions were presented. The best corrosion resistance characteristics are exhibited by TiN/Al2O3 multilayer coatings on both stainless steel and titanium substrates.

Zykova, A.; Safonov, V.; Walkowich, J.; Rogowska, R.; Yakovin, S.

2010-04-01

88

Influence of bi-layer period thickness on the residual stress, mechanical and tribological properties of nanolayered TiAlN\\/CrN multi-layer coatings  

Microsoft Academic Search

TiAlN\\/CrN nanoscale multi-layered coatings have been deposited using cathodic arc evaporation system. The coatings were deposited using one Ti50Al50 alloy target and one Cr target with a fixed target power in all the processes, while the bi-layer thickness was varied by various rotation speeds of the substrate holder in order to produce different nanoscale multi-layered period thickness. The texture structure,

Chi-Lung Chang; Jui-Yun Jao; Wei-Yu Ho; Da-Yung Wang

2007-01-01

89

Magnetic multilayers on nanospheres.  

NASA Astrophysics Data System (ADS)

In modern magnetic recording materials the `superparamagnetic effect' [1] has become increasingly important as new magnetic hard disk drive products are designed for higher storage densities. In this regard, nanoparticle media [2], where two-dimensional arrays of monodisperse nanoparticles with high magnetic anisotropy are used, is assumed to be the ideal future magnetic recording material. In this presentation a novel magnetic gradient nanomaterial, which has been created by depositing Co/Pd multilayers onto two-dimensional arrays of self-assembled nanoparticles [3] will be introduced. The magnetic nanostructures formed on top of the particles are in a magnetically exchange-isolated quasi-single-domain state. This nanoscale system is quite distinct from the classical geometries: Neither extrinsic properties nor the intrinsic properties are uniform in space. The film is extended over a wide region of the sphere and thus shows substantial curvature. The film thickness varies and so do the intrinsic magnetic properties most notable the magneto-crystalline anisotropy, which is a key factor affecting the fundamental nature of the reversal process. The specific magnetic characteristics of such a gradient nanomaterial and in particular its impact on the reversal mechanism will be discussed. Angle-dependent reversal studies were performed for different particle sizes and the experimental results were interpreted using micromagnetic simulations. The simulations account for the angular dependence of the hysteresis loops and provide a detailed picture of how the local magnetization evolves during reversal, offering new opportunities in the functionalization of magnetic nanostructures for storage applications. [1] A. Moser et al., J. Phys. D: Appl. Phys. 35, (2002) R157. [2] S. Sun et al., Science 87, (2000) 1989. [3] M. Albrecht et al., Nature Mater. 4, (2005) 203.

Albrecht, Manfred

2006-03-01

90

Nanoscale Science and Engineering (NSE)  

NSF Publications Database

for Nanoscale Science and Engineering Centers (NSEC): Full proposals may ONLY be submitted by invitation from NSF. The National Science Foundation (NSF) announces a program on collaborative research and education in the area of nanoscale science and engineering. The goal of this program is to support fundamental research and catalyze synergistic science and engineering research and education in emerging areas of nanoscale science and technology, including: biosystems at the nanoscale; ...

91

Exploring at the Nanoscale  

NSDL National Science Digital Library

This lesson focuses on how nanotechnology has impacted our society and how engineers have learned to explore the world at the nanoscale. Learners participate in hands-on activities to understand exactly how small the nanoscale is, explore how surface area changes at the nano scale, and work in teams to develop futuristic applications of nanotechnology. Specifically, teams of learners examine and measure blocks of tofu or gelatin to determine the surface area. Then they slice the blocks into smaller and smaller pieces, exposing more surfaces, and impacting the surface area. Learners also explore the size of small by comparing various items to understand the size of nano.

Ieee

2013-02-25

92

HIPIMS and MPP Sputtered TA Films Using I-PVD Technology.  

National Technical Information Service (NTIS)

HIPIMS (high power impulse magnetron sputtering) process utilizing I- PVD technology can produce high ionization, high flux, and high intensity plasma. The metal ions from the target can be used for substrate etching and for the deposition of improved qua...

B. Abraham F. Yee M. Cipollo R. Chistyakov S. L. Lee

2009-01-01

93

Tribological testing of some potential PVD and CVD coatings for steel wire drawing dies  

Microsoft Academic Search

The aim of this study was to investigate the possibility to replace cemented carbide wire drawing dies with CVD or PVD coated steel dies. Material pick-up tendency, friction and wear characteristics of four different commercial coatings – CVD TiC and PVD (Ti,Al)N, CrN and CrC\\/C – in sliding contact with ASTM 52100 bearing steel were evaluated using pin-on-disc testing. The

Maria Nilsson; Mikael Olsson

2011-01-01

94

PEGDA\\/PVdF\\/F127 gel type polymer electrolyte membranes for lithium secondary batteries  

Microsoft Academic Search

A novel porous gel polymer electrolyte (GPE) membrane based on poly(ethylene glycol) diacrylate (PEGDA), poly(vinylidene fluoride) (PVdF), and polyethylene oxide-co-polypropylene oxide-co-polyethylene oxide (PEO-PPO-PEO, F127) was fabricated by a phase inversion technique. The PEGDA cross-linking oligomer could be randomly mixed with unraveled PVdF polymer chains to form the interpenetrating polymer network (IPN) structure. Several experimental techniques including infrared (IR) spectra, differential

Yan-Jie Wang; Dukjoon Kim

2007-01-01

95

Characterization of commercial EB-PVD TBC systems with CVD (Ni,Pt)Al bond coatings  

Microsoft Academic Search

Failure of electron-beam physical vapor deposition (EB-PVD) thermal barrier coatings (TBCs) with aluminide bond coats is strongly influenced by bond coat oxidation behavior. This study investigated oxide (Al2O3) formation during EB-PVD processing of TBCs with (Ni,Pt)Al bond coats. The effects of substrate composition, coating impurities and bond-coat grit-blasting on the oxide phases, residual stress and microstructure were evaluated. As-deposited, high-purity

J. A Haynes; M. J Lance; B. A Pint; I. G Wright

2001-01-01

96

Microstructure of PVdF- co-HFP based electrolyte prepared by preferential polymer dissolution process  

Microsoft Academic Search

A preferential polymer dissolution process was proposed for preparation of PVdF-co-HFP based membranes using PVA as the preferential polymer. The porosity and electrolyte uptake of membrane increases with removal of PVA content in the PVdF-co-HFP matrix. Scanning electron microscopy and gas adsorption\\/desorption method were used to reveal the porous structure of the polymer membranes. The ionic conductivity of porous polymer

N. T. Kalyana Sundaram; A. Subramania

2007-01-01

97

Conductivity behaviour of proton conducting polymer gel electrolytes with PVdF-HFP  

Microsoft Academic Search

Electrical conductivity of polymer gel electrolytes containing different hydroxy substituted benzoic acids and polyvinylidenefluoride-hexafluoropropylene (PVdF-HFP) has been studied. The conductivity of solution and gel electrolytes shows ortho effect and has been found to depend upon the acidity constant of the acid used and varies as ? (ortho-)>? (meta-)> ? (para-). The addition of PVdF-HFP to solution electrolytes results in an

Harinder Pal Singh; S. S Sekhon

2003-01-01

98

Thermal and ionic conductivity studies of plasticized PMMA\\/PVdF blend polymer electrolytes  

Microsoft Academic Search

Poly(methylmethacrylate) (PMMA)\\/poly(vinylidene fluoride) (PVdF) blend based electrolyte films containing different lithium salt concentrations are prepared using solvent casting technique. The complexation has been confirmed using XRD and FTIR spectral studies. Ionic conductivity and thermal behaviour of PMMA\\/PVdF complexes were studied with various salt concentrations, temperature and plasticizer content. The network structure of the polymer complexes are also investigated using SEM.

S Rajendran; O Mahendran; T Mahalingam

2002-01-01

99

Advanced PVD-TiAlN coatings on carbide and cermet cutting tools  

Microsoft Academic Search

Significant advances have been made in the process design and development of PVD-TiAlN coatings for carbide and cermet cutting tools. Higher plasma ionization in the TiAlN deposition process creates coatings with dense microstructure and excellent adhesion characteristics. The resulting new generation of PVD-TiAlN coatings provide increased productivity in a wide range of machining operations and work-piece materials. This paper discusses

H. G. Prengel; A. T. Santhanam; R. M. Penich; P. C. Jindal; K. H. Wendt

1997-01-01

100

Mechanical properties of EB-PVD-thermal barrier coatings by nanoindentation  

Microsoft Academic Search

In the present work EB-PVD zirconia thermal barrier coatings were examined by nanoindentation. Because of the microstructure of EB-PVD-coatings, the mechanical properties in the vertical and the horizontal direction are completely different. Therefore the indents were performed on cross-sections and on the coatings’ surface itself. Because of the expected different behavior at the grain boundaries and the grains, the measurement

E. Lugscheider; K. Bobzin; S. Bärwulf; A. Etzkorn

2001-01-01

101

Cyclic behavior of EB-PVD thermal barrier coating systems with modified bond coats  

Microsoft Academic Search

The lifetime of thermal barrier coating (TBC) systems depends on substrate, bond coat, thermally grown oxide (TGO), and ceramic top coat. In the present paper NiPtAl bond coats as well as NiCoCrAlY(X) deposited by LPPS and EB-PVD (electron-beam physical vapour deposition) underneath conventional EB-PVD yttria stabilized zirconia top coats were investigated on three different substrate alloys. Several bond coat treatments

Uwe Schulz; Klaus Fritscher; Andrea Ebach-Stahl

2008-01-01

102

Sintering and failure behaviour of EB-PVD thermal barrier coating after isothermal treatment  

Microsoft Academic Search

Electron beam-physical vapour deposition (EB-PVD) yttria-stabilised zirconia (YSZ) thermal barrier coatings (TBCs) were exposed to isothermal treatments at 1050, 1150 and 1200 °C. The as-deposited EB-PVD TBCs have typical columnar microstructure with larger columns near the top surface than that near the TBC\\/substrate interface. The difference in microstructure of TBCs across its thickness leads to difference in degree of sintering.

X. Zhao; X. Wang; P. Xiao

2006-01-01

103

Improved Thermal Cycling Durability of Thermal Barrier Coatings Manufactured by PS-PVD  

NASA Astrophysics Data System (ADS)

The plasma spray-physical vapor deposition (PS-PVD) process is a promising method to manufacture thermal barrier coatings (TBCs). It fills the gap between traditional thermal spray processes and electron beam physical vapor deposition (EB-PVD). The durability of PS-PVD manufactured columnar TBCs is strongly influenced by the compatibility of the metallic bondcoat (BC) and the ceramic TBC. Earlier investigations have shown that a smooth BC surface is beneficial for the durability during thermal cycling. Further improvements of the bonding between BC and TBC could be achieved by optimizing the formation of the thermally grown oxide (TGO) layer. In the present study, the parameters of pre-heating and deposition of the first coating layer were investigated in order to adjust the growth of the TGO. Finally, the durability of the PS-PVD coatings was improved while the main advantage of PS-PVD, i.e., much higher deposition rate in comparison to EB-PVD, could be maintained. For such coatings, improved thermal cycling lifetimes more than two times higher than conventionally sprayed TBCs, were measured in burner rigs at ~1250 °C/1050 °C surface/substrate exposure temperatures.

Rezanka, S.; Mauer, G.; Vaßen, R.

2014-01-01

104

Nanoscale magnetic structure of ferromagnet/antiferromagnet manganite multilayers.  

PubMed

We use polarized neutron reflectometry and dc magnetometry to obtain a comprehensive picture of the magnetic structure of a series of La(2/3)Sr(1/3)MnO3/Pr(2/3)Ca(1/3)MnO3 (LSMO/PCMO) superlattices, with varying thickness of the antiferromagnetic (AFM) PCMO layers (0

Niebieskikwiat, D; Hueso, L E; Borchers, J A; Mathur, N D; Salamon, M B

2007-12-14

105

Nanoscale Magnetic Structure of Ferromagnet/Antiferromagnet Manganite Multilayers  

SciTech Connect

We use polarized neutron reflectometry and dc magnetometry to obtain a comprehensive picture of the magnetic structure of a series of La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/Pr{sub 2/3}Ca{sub 1/3}MnO{sub 3} (LSMO/PCMO) superlattices, with varying thickness of the antiferromagnetic (AFM) PCMO layers (0{<=}t{sub A}{<=}7.6 nm). While LSMO presents a few magnetically frustrated monolayers at the interfaces with PCMO, in the latter a magnetic contribution due to ferromagnetic (FM) inclusions within the AFM matrix is maximized at t{sub A}{approx}3 nm. This enhancement of FM moment occurs at the matching between layer thickness and cluster size, implying the possibility of tuning phase separation by imposing appropriate geometrical constraints which favor the accommodation of FM nanoclusters within the ''non-FM'' material.

Niebieskikwiat, D. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Colegio de Ciencias e Ingenieria, Universidad San Francisco de Quito, Quito (Ecuador); Hueso, L. E. [Department of Materials Science, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Borchers, J. A. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Mathur, N. D. [Department of Materials Science, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Salamon, M. B. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2007-12-14

106

PVD coating for optical applications on temperature-resistant thermoplastics  

NASA Astrophysics Data System (ADS)

The performance of the high temperature resistant polymers Pleximid, APEC and Ultrason as substrate materials in plasma-assisted physical vapor deposition processes was studied and compared with well-known thermoplastics for optical applications. Different effects of UV irradiation and plasma exposure on the polymers' optical features, surface energy and adhesion properties for oxide layers, typically used for interference multilayer coatings, are shown.

Munzert, Peter; Schulz, Ulrike; Kaiser, Norbert

2004-02-01

107

Nanoscale plasmonic circulator  

NASA Astrophysics Data System (ADS)

Breaking time reversal symmetry of the light flow, implying optical wave isolation and directional light guiding, is crucial for signal handling and integrated optics. Such signal isolation is possible with an optical circulator—a three-port magneto-active nonreciprocal device, which transmits light from any of its input ports into the next port in a circular order, isolating the remaining port. Small magneto-optical activity at optical frequencies challenges the miniaturization and further on-chip integration of this key fundamental component. Here we demonstrate theoretically that by employing principles of plasmonic mode engineering it is possible to enhance significantly magneto-optical response in a deep subwavelength regime and suggest a conceptual approach for a design of an ultracompact nanoscale passive optical circulator. This work paves the way for future generation of nonreciprocal integrated optics with a nanoscale on-chip compatibility.

Davoyan, Arthur R.; Engheta, Nader

2013-08-01

108

Tunable nanoscale graphene magnetometers.  

PubMed

The detection of magnetic fields with nanoscale resolution is a fundamental challenge for scanning probe magnetometry, biosensing, and magnetic storage. Current technologies based on giant magnetoresistance and tunneling magnetoresistance are limited at small sizes by thermal magnetic noise and spin-torque instability. These limitations do not affect Hall sensors consisting of high mobility semiconductors or metal thin films, but the loss of magnetic flux throughout the sensor's thickness greatly limits spatial resolution and sensitivity. Here we demonstrate graphene extraordinary magnetoresistance devices that combine the Hall effect and enhanced geometric magnetoresistance, yielding sensitivities rivaling that of state of the art sensors but do so with subnanometer sense layer thickness at the sensor surface. Back-gating provides the ability to control sensor characteristics, which can mitigate both inherent variations in material properties and fabrication-induced device-to-device variability that is unavoidable at the nanoscale. PMID:20030395

Pisana, Simone; Braganca, Patrick M; Marinero, Ernesto E; Gurney, Bruce A

2010-01-01

109

Collaboration at the Nanoscale  

NSDL National Science Digital Library

The Maine ScienceCorps is a project sponsored by the National Science Foundation's (NSF) Graduate Teaching Fellows in K-12 Education (GK-12 ) program. Through this program, the University of Southern Maine's (USM) virology and transmission electron microscopy (TEM) research group provides high school teachers and students in rural areas with access to the nanoscale world of viruses. This article illustrates how access to the university research community's advanced technological resources can enrich science learning in high school classrooms.

Jamison, Jennifer L.; Moulton, Karen D.; Duboise, S. M.

2009-04-01

110

Plasma Spray-PVD: A New Thermal Spray Process to Deposit Out of the Vapor Phase  

NASA Astrophysics Data System (ADS)

Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years. In comparison to conventional vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS), the new proposed process uses a high energy plasma gun operated at a reduced work pressure of 0.1 kPa (1 mbar). Owing to the high energy plasma and further reduced work pressure, PS-PVD is able to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Owing to the forced gas stream of the plasma jet, complex shaped parts such as multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas which are not in the line of sight of the coating source can be coated homogeneously. This article reports on the progress made by Sulzer Metco in developing a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of Yttria-stabilized Zircona (YSZ) are optimized to serve in a turbine engine. This process includes not only preferable coating properties such as strain tolerance and erosion resistance but also the simultaneous coverage of multiple air foils.

von Niessen, Konstantin; Gindrat, Malko

2011-06-01

111

Science Sampler: Nanoscale in perspective  

NSDL National Science Digital Library

Nanoscale science is a growing field, and to appreciate the work of scientists in this field, it is important for students to understand the scale of work being done. This activity, designed to bring nanoscale into the familiar macroworld, is from a two-week workshop on nanotechnology conducted by Fisk University in Nashville, Tennessee that was sponsored by the National Center for Learning and Teaching in Nanoscale Science and Engineering (NCLT) and the National Science Foundation (NSF).

Cherry, Elvis H.; Chang, R. P.; Lu, Weijie

2008-04-01

112

Microstructures and mechanical properties of sputtered Cu/Cr multilayers  

SciTech Connect

The microstructures and mechanical properties of Cu/Cr multilayers prepared by sputtering onto {l_brace}100{r_brace} Si substrates at room temperature are presented. The films exhibit columnar grain microstructures with nanoscale grain sizes. The interfaces are planar and abrupt with no intermixing, as expected from the phase diagram. The multilayers tend to adopt a Kurdjumov-Sachs (KS) orientation relationship: {l_brace}110{r_brace}Cr // {l_brace}111{r_brace}Cu, <111>Cr // <110>Cu. The hardness of the multilayered structures, as measured by nanoindentation, increase with decreasing layer thickness for layer thicknesses ranging from 200 nm to 50 nm, whereas for lower thicknesses the hardness of the multilayers is independent of the layer thickness. Dislocation-based models are used to interpret the variation of hardness with layer periodicity. The possible effects of factors such as grain size within the layers, density and composition of films and residual stress in the multilayers are highlighted. Comparisons are made to the mechanical properties of sputtered polycrystalline Cu/Nb multilayers which, like Cu/Cr, exhibit sharp fcc/bcc interfaces with no intermixing and a KS orientation relationship, but have a small shear modulus mismatch.

Misra, A.; Kung, H.; Mitchell, T.E.; Jervis, T.R.; Nastasi, M.

1998-03-01

113

The effect of nanolayer thickness on the structure and properties of multilayer TiN/MoN coatings  

NASA Astrophysics Data System (ADS)

The effect of nanolayer thickness on the structure and properties of nanocomposite multilayer TiN/MoN coatings is revealed. The multilayer (alternating) TiN/MoN coatings are prepared by the Arc-PVD method. The selected thickness of the nanolayers is 2, 10, 20, and 40 nm. The formation of two phases—TiN (fcc) and ?-Mo2N—is found. The ratio of Ti and Mo concentrations varies with varying layer thickness. The maximum hardness value obtained for different thicknesses of the layers does not exceed 28-31 GPa. The stability of TiN/MoN during cutting and tribological tests is significantly higher than that of products with TiN coatings. The nanostructured multilayer coatings with layer thicknesses of 10 and 20 nm exhibit the lowest friction coefficient of 0.09-0.12.

Pogrebnjak, A. D.; Beresnev, V. M.; Bondar, O. V.; Abadias, G.; Chartier, P.; Postol'nyi, B. A.; Andreev, A. A.; Sobol', O. V.

2014-03-01

114

Multilayer Insulation Material Guidelines  

NASA Technical Reports Server (NTRS)

Multilayer Insulation Material Guidelines provides data on multilayer insulation materials used by previous spacecraft such as Spacelab and the Long-Duration Exposure Facility and outlines other concerns. The data presented in the document are presented for information only. They can be used as guidelines for multilayer insulation design for future spacecraft provided the thermal requirements of each new design and the environmental effects on these materials are taken into account.

Finckenor, M. M.; Dooling, D.

1999-01-01

115

Structural characterization and high-throughput screening of inhibitors of PvdQ, an NTN hydrolase involved in pyoverdine synthesis.  

PubMed

The human pathogen Pseudomonas aeruginosa produces a variety of virulence factors including pyoverdine, a nonribosomally produced peptide siderophore. The maturation pathway of the pyoverdine peptide is complex and provides a unique target for inhibition. Within the pyoverdine biosynthetic cluster is a periplasmic hydrolase, PvdQ, that is required for pyoverdine production. However, the precise role of PvdQ in the maturation pathway has not been biochemically characterized. We demonstrate herein that the initial module of the nonribosomal peptide synthetase PvdL adds a myristate moiety to the pyoverdine precursor. We extracted this acylated precursor, called PVDIq, from a pvdQ mutant strain and show that the PvdQ enzyme removes the fatty acid catalyzing one of the final steps in pyoverdine maturation. Incubation of PVDIq with crystals of PvdQ allowed us to capture the acylated enzyme and confirm through structural studies the chemical composition of the incorporated acyl chain. Finally, because inhibition of siderophore synthesis has been identified as a potential antibiotic strategy, we developed a high-throughput screening assay and tested a small chemical library for compounds that inhibit PvdQ activity. Two compounds that block PvdQ have been identified, and their binding within the fatty acid binding pocket was structurally characterized. PMID:21892836

Drake, Eric J; Gulick, Andrew M

2011-11-18

116

High-temperature multilayers  

NASA Astrophysics Data System (ADS)

The effect of elevated temperatures on the optical and structural stability of MoSi2/Si and Mo/C/Si/C multilayer coatings was investigated. The multilayer mirrors were designed for normal-incidence reflectivity at a wavelength of about 13.5 nm. The multilayers were deposited by dc-magnetron sputtering and subsequently annealed at temperatures of 400 °C and 500 °C for 1, 10 and 100 hours. X-ray scattering, transmission electron microscopy, atomic force microscopy and normal-incidence reflectivity measurements were used for the characterization of the multilayer structures. We achieved maximal normal-incidence reflectivities of 41.2 % and 59.6 % for as-deposited MoSi2/S and Mo/C/Si/C multilayer mirrors. While the optical properties of Mo/C/Si/C multilayers changed monotonically during annealing time at temperatures of more than 400 °C, the MoSi2/Si multilayers showed a superior thermal stability up to 500 °C. New barrier layer materials were also suggested to enhance the thermal stability of Mo/Si multilayers. Interface-engineered Mo/Si multilayer mirrors were designed to combine both a high reflectivity of more than 60 % at 13.5 nm and a superior long-term thermal stability of up to 500 °C.

Yulin, Sergiy; Benoit, Nicolas; Feigl, Torsten; Kaiser, Norbert

2005-05-01

117

PvdP Is a Tyrosinase That Drives Maturation of the Pyoverdine Chromophore in Pseudomonas aeruginosa.  

PubMed

The iron binding siderophore pyoverdine constitutes a major adaptive factor contributing to both virulence and survival in fluorescent pseudomonads. For decades, pyoverdine production has allowed the identification and classification of fluorescent and nonfluorescent pseudomonads. Here, we demonstrate that PvdP, a periplasmic enzyme of previously unknown function, is a tyrosinase required for the maturation of the pyoverdine chromophore in Pseudomonas aeruginosa. PvdP converts the nonfluorescent ferribactin, containing two iron binding groups, into a fluorescent pyoverdine, forming a strong hexadentate complex with ferrous iron, by three consecutive oxidation steps. PvdP represents the first characterized member of a small family of tyrosinases present in fluorescent pseudomonads that are required for siderophore maturation and are capable of acting on large peptidic substrates. PMID:24816606

Nadal-Jimenez, Pol; Koch, Gudrun; Reis, Carlos R; Muntendam, Remco; Raj, Hans; Jeronimus-Stratingh, C Margot; Cool, Robbert H; Quax, Wim J

2014-07-15

118

Integrated arc suppression unit for defect reduction in PVD applications  

NASA Astrophysics Data System (ADS)

Arcing between the target and plasma during PVD deposition causes substantial damage to the target and splats and other contamination on the deposited films. Arc-related damages and defects are frequently encountered in microelectronics manufacturing and contributes largely to reduced wafer yields. Arcing is caused largely by the charge buildup at the contaminated sites on the target surface that contains either nonconducting inclusions or nodules. Arc suppression is a key issue for defect reduction, yield improvement and for reliable high quality metallization. An Integrated Arc Suppression Unit (IASU) has been designed for Endura HP PVDTM sputtering sources. The integrated design reduces cable length from unit to source and reduces electrical energy stored in the cable. Active arc handling mode, proactive arc prevention mode, and passive by-pass arc counting mode are incorporated into the same unit. The active mode is designed to quickly respond to chamber conditions, like a large chamber voltage drop, that signals a arc. The self run mode is designed to proactively prevent arc formation by pulsing and reversing target voltage at 50 kHz. The design of the IASU, also called mini small package arc repression circuit--low energy unit (mini Sparc-le), has been optimized for various DC magnetron sources, plasma stability, chamber impedance, power matching, CE MARK test, and power dissipation. Process characterization with Ti, TiN and Al sputtering indicates that the unit has little adverse impact on film properties. Mini Sparc-le unit has been shown here to significantly reduce splats occurrence in Al sputtering. Marathon test of the unit with Ti/TiN test demonstrated the unit's reliability and its ability to reduce sensitivity of defects to target characteristics.

Li, Xiangbing; Narasimhan, Murali K.; Pavate, Vikram; Loo, David; Rosenblum, Steve; Trubell, Larry; Scholl, Richard; Seamons, Scott; Hagerty, Chris; Ramaswami, Sesh

1997-09-01

119

Nanotribology and Nanoscale Friction  

SciTech Connect

Tribology is the science and technology of contacting solid surfaces in relative motion, including the study of lubricants, lubrication, friction, wear, and bearings. It is estimated that friction and wear cost the U.S. economy 6% of the gross national product (Persson, 2000). For example, 5% of the total energy generated in an automobile engine is lost to frictional resistance. The study of nanoscale friction has a technological impact in reducing energy loss in machines, in microelectromechanical systems (MEMS), and in the development of durable, low-friction surfaces and ultra-thin lubrication films.

Guo, Yi [Stevens Institute of Technology, Hoboken, New Jersey; Qu, Zhihua [University of Central Florida, Orlando; Braiman, Yehuda [ORNL; Zhang, Zhenyu [ORNL; Barhen, Jacob [ORNL

2008-01-01

120

Influence of EB-PVD TBC Microstructure on Thermal Barrier Coating System Performance Under Cyclic Conditions  

Microsoft Academic Search

The lifetimes of electron beam physical vapor deposited (EB-PVD) thermal barrier;\\u000acoating systems (TBCs) with three different microstructures of the Y2<\\/sub>O3<\\/sub>-stabilized ZrO, YSZ) ceramic top layer were investigated in lh thermal cycles at 1100 and 1150°C in flowing oxygen. Single crystal alloys CMSX-4 and Rene N5 that had been coated with an EB-PVD NiCoCrAlY bond coat were chosen as substrate

C. Leyens; B. A. Pint; U. Schulz; I. G. Wright

1999-01-01

121

Nanoscale control designs for systems.  

PubMed

Nanoscale control is the science of the control of objects at dimensions with 100 nm or less and the manipulation of them at this level of precision. The desired attributes of systems under nanoscale control design are extreme high resolution, accuracy, stability, and fast response. An important perspective of investigation in nanoscale control design includes system modeling and precision control devices and materials at a nanoscale dimension, i.e., design of nanopositioners. Nanopositioners are mechatronic systems with an ultraprecise resolution down to a fraction of an atomic diameter and developed to move objects over a small range in nanoscale dimension. After reviewing a lot of existing literatures for nanoscale control designs, the way to successful nanoscale control is accurate position sensing and feedback control of the motion. An overview of nanoscale identification, linear, and nonlinear control technologies, and devices that are playing a key role in improving precision, accuracy, and response of operation of these systems are introduced in this research. PMID:24749455

Chen, Yung-Yue

2014-02-01

122

Flexoelectricity in Nanoscale Ferroelectrics  

NASA Astrophysics Data System (ADS)

All ferroelectrics are piezoelectric and thus have an intrinsic coupling between polarization and strain. There exists an additional electromechanical coupling, however, between polarization and strain gradients. Strain gradients are intrinsically vectorial fields and, therefore, they can in principle be used to modify both the orientation and the sign of the polarization, thanks to the coupling known as flexoelectricity. Flexoelectricity is possible even in paraelectric materials, but is generally stronger in ferroelectrics on account of their high permittivity (the flexoelectric coefficient is proportional to the dielectric constant). Moreover, strain gradients can be large at the nanoscale due to the smallness of the relaxation length and, accordingly, strong flexoelectric effects can be expected in nanoscale ferroelectrics. In this talk we will present two recent results that highlight the above features. In the first part, I will show how polarization tilting can be achieved in a nominally tetragonal ferroelectric (PbTiO3) thanks to the internal flexoelectric fields generated in nano-twinned epitaxial thin films. Flexoelectricity thus offers a purely physical means of achieving rotated polarizations, which are thought to be useful for enhanced piezoelectricity. In the second part, we will show how the large strain gradients generated by pushing the sharp tip of an atomic force microscope against the surface of a thin ferroelectric film can be used to actively switch its polarity by 180^o. This enables a new concept for ``multiferroic'' memory operation in which the memory bits are written mechanically and read electrically.

Catalan, Gustau

2012-02-01

123

Nanoscale relaxation oscillator  

DOEpatents

A nanoscale oscillation device is disclosed, wherein two nanoscale droplets are altered in size by mass transport, then contact each other and merge through surface tension. The device may also comprise a channel having an actuator responsive to mechanical oscillation caused by expansion and contraction of the droplets. It further has a structure for delivering atoms between droplets, wherein the droplets are nanoparticles. Provided are a first particle and a second particle on the channel member, both being made of a chargeable material, the second particle contacting the actuator portion; and electrodes connected to the channel member for delivering a potential gradient across the channel and traversing the first and second particles. The particles are spaced apart a specified distance so that atoms from one particle are delivered to the other particle by mass transport in response to the potential (e.g. voltage potential) and the first and second particles are liquid and touch at a predetermined point of growth, thereby causing merging of the second particle into the first particle by surface tension forces and reverse movement of the actuator. In a preferred embodiment, the channel comprises a carbon nanotube and the droplets comprise metal nanoparticles, e.g. indium, which is readily made liquid.

Zettl, Alexander K. (Kensington, CA); Regan, Brian C. (Los Angeles, CA); Aloni, Shaul (Albany, CA)

2009-04-07

124

Modular, Multilayer Perceptron  

NASA Technical Reports Server (NTRS)

Combination of proposed modular, multilayer perceptron and algorithm for its operation recognizes new objects after relatively brief retraining sessions. (Perceptron is multilayer, feedforward artificial neural network fully connected and trained via back-propagation learning algorithm.) Knowledge pertaining to each object to be recognized resides in subnetwork of full network, therefore not necessary to retrain full network to recognize each new object.

Cheng, Li-Jen; Liu, Tsuen-Hsi

1991-01-01

125

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam  

NASA Astrophysics Data System (ADS)

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 ?m and 90 nm, respectively. Their aspect ratio was about 17.

Naoyuki Fukutake,; Nozomi Miyoshi,; Yuya Takasawa,; Tatsuya Urakawa,; Tomoko Gowa,; Kazumasa Okamoto,; Akihiro Oshima,; Seiichi Tagawa,; Masakazu Washio,

2010-06-01

126

Information storage materials: nanoscale characterisation by three-dimensional atom probe analysis  

SciTech Connect

The development of nanoscale magnetic materials for applications in information storage systems relies heavily on the ability to engineer the properties of the layered structures from which such materials are fabricated. These properties are strongly dependent on the nature of the interfaces between the individual nanoscale magnetic layers, so knowledge of the interface chemistry is crucial. In this paper, we discuss the application of three-dimensional atom probe analysis to the characterisation of layered magnetic materials, including details of specimen preparation techniques required for this type of analysis. Recent results are presented on the characterisation of interfaces in Co/Cu or CoFe/Cu multilayers, which form part of the read sensor in magnetic recording heads, and Co/Pd multilayers, which are being considered for use as perpendicular recording media.

Larson, D.J.; Petford-Long, A.K.; Ma, Y.Q; Cerezo, A

2004-06-07

127

Two-source jumping beam evaporation for advanced EB-PVD TBC systems  

Microsoft Academic Search

The continuous increase of the turbine inlet temperature in gas turbines necessitates new TBCs with a temperature capability beyond the current partially yttria stabilized material coatings. The present paper focuses on two-source jumping EB-PVD processed novel candidate layers for future TBC applications. It is shown that mixtures of oxides with widely different vapor pressures can be manufactured by this technique.

U. Schulz; K. Fritscher; C. Leyens

2000-01-01

128

Nano and Micro indentation studies of bulk zirconia and EB PVD TBCs  

Microsoft Academic Search

In order to model the erosion of a material, it is necessary to know the material properties of both the impacting particles as well as the target. In the case of electron beam (EB) physical vapour deposited (PVD) thermal barrier coatings (TBCs) the properties of the columns as opposed to the coating as a whole are important. This is due

R. G. Wellman; A. Dyer; J. R. Nicholls

2004-01-01

129

Optimizing the target-to-wafer spacing for highly uniform PVD films  

NASA Astrophysics Data System (ADS)

This research examines the optimum spacing between the Physical Vapor Deposition (PVD) target and the wafer substrate, at various stages in the erosion life of the target. As the target erodes, the surface becomes uneven with ring shaped grooves. This effects the radial distribution of material flux onto the wafer, and requires the wafer to be moved further from the target. The optimal target to wafer spacing is plotted against target lifetime for different types of chamber configurations and target materials. Target materials are Ti, TiN, and Al, and chamber configurations are standard Magnetron PVD, Collimated PVD, and Ionized Metal Plasma (IMP) PVD. TiN chambers with Dura TTN magnets show predictable behavior during the life of the target, while Type A magnets and all other chamber configurations show almost now drift in the optimum spacing. Thus, it was decided only Dura TTN (TiN) chambers required spacing compensation. Rate-of- change constants for TiN chambers were input into software provided by Applied Materials, to dynamically adjust the spacing as the target erodes. Thickness uniformity of less than 1% was maintained throughout the target's 1600 KWHrs life.

Paton, Eric; Pena, Ray; Morioka, Jeff; Sprock, Karen; Morillo, Jesus; Tsu, Kao S.

1999-09-01

130

Assessment of gradient and nanogradient PVD coatings behaviour under erosive, abrasive and impact wear conditions  

Microsoft Academic Search

PVD coatings are of great interest due to their high hardness, wear and oxidation resistance, thermal stability and lubricity. Gradient deposition technology allows improving adhesion to substrate and mechanical properties of the coating-substrate system by elimination of the mismatch in materials properties at the interface and reduction of residual stresses. The present study aims at the assessment of performance of

M. Antonov; I. Hussainova; F. Sergejev; P. Kulu; A. Gregor

2009-01-01

131

Influence of bias variation on residual stress and texture in TiAlN PVD coatings  

Microsoft Academic Search

It is recognized that the quality and performance of PVD coatings on tungsten carbide based cutting tools are strongly affected by the level of residual stress as it may cause the coatings to delaminate from the substrate and affect the tool life. Here we report on the substrate bias as an important parameter to affect the compressive stress and the

M. Ahlgren; H. Blomqvist

2005-01-01

132

Erosion, corrosion and erosion–corrosion of EB PVD thermal barrier coatings  

Microsoft Academic Search

Electron beam (EB) physical vapour deposited (PVD) thermal barrier coatings (TBCs) have been used in gas turbine engines for a number of years. The primary mode of failure is attributed to oxidation of the bond coat and growth of the thermally grown oxide (TGO), the alumina scale that forms on the bond coat and to which the ceramic top coat

R. G. Wellman; J. R. Nicholls

2008-01-01

133

Photovoltaics at the nanoscale  

NASA Astrophysics Data System (ADS)

Nanoscale thin film morphology has been identified as an important factor in organic solar cell device func- tionality and efficiency. To better understand the limiting factors, it is important to work at the length scale of these processes. A study of thin films of organic molecules with Kelvin probe force microscopy (KPFM) to observe charge distribution and non-contact atomic force microscopy (NC-AFM) to simultaneously obtain structural information is presented. This allows investigation of the structure-function relationships in molecu- lar photovoltaics at the nanometer scale. PTCDI (3,4,9,10-perylenetetracarboxylic diimide) and CuPc (copper phthalocyanine) are used as organic molecules and are precisely grown on alkali halide substrates.

Schumacher, Zeno; Topple, Jessica; Tekiel, Antoni; Grütter, Peter

2013-09-01

134

Multilayer dielectric diffraction gratings  

DOEpatents

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

Perry, Michael D. (Livermore, CA); Britten, Jerald A. (Oakley, CA); Nguyen, Hoang T. (Livermore, CA); Boyd, Robert (Livermore, CA); Shore, Bruce W. (Livermore, CA)

1999-01-01

135

Multilayer dielectric diffraction gratings  

DOEpatents

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

1999-05-25

136

Nanophotonics: Nanoscale Optical Science and Technology  

Microsoft Academic Search

\\u000a Nanophotonics defined as nanoscale optical science and technology is a new frontier, which includes nanoscale confinement\\u000a of radiation, nanoscale confinement of matter, and nanoscale photophysical or photochemical transformation. Selected examples\\u000a of our research work in each of these areas are presented here. Nonlinear optical interactions involving nanoscale confinement\\u000a of radiation is both theoretically and experimentally studied using a near-field geometry.

Paras N. Prasad; Yuzhen Shen; Abani Biswas; Jeff Winiarz

137

Wedged multilayer Laue lens  

SciTech Connect

A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures.

Conley, Ray; Liu Chian; Qian Jun; Kewish, Cameron M.; Macrander, Albert T. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Yan Hanfei; Maser, Joerg [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kang, Hyon Chol; Stephenson, G. Brian [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2008-05-15

138

Wedged multilayer Laue Lens.  

SciTech Connect

A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures.

Conley, R.; Liu, C.; Qian, J.; Kewish, C. M.; Macrander, A. T.; Yan, H.; Kang, H. C.; Maser, J.; Stephenson, G. B.

2008-05-01

139

Wedged multilayer Laue lens.  

PubMed

A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures. PMID:18513058

Conley, Ray; Liu, Chian; Qian, Jun; Kewish, Cameron M; Macrander, Albert T; Yan, Hanfei; Kang, Hyon Chol; Maser, Jörg; Stephenson, G Brian

2008-05-01

140

Multilayer Perceptrons for Classification.  

National Technical Information Service (NTIS)

Techniques for training, testing, and validating multilayer perceptrons are thoroughly examined. Results obtained using perceptrons are compared and contrasted with two multivariate discriminant analysis techniques-logistic regression and k neighbor. Meth...

L. M. Belue

1992-01-01

141

Transcriptional control of the pvdS iron starvation sigma factor gene by the master regulator of sulfur metabolism CysB in Pseudomonas aeruginosa.  

PubMed

In the Gram-negative pathogen Pseudomonas aeruginosa, the alternative sigma factor PvdS acts as a key regulator of the response to iron starvation. PvdS also controls P. aeruginosa virulence, as it drives the expression of a large set of genes primarily implicated in biogenesis and transport of the pyoverdine siderophore and synthesis of extracellular factors, such as protease PrpL and exotoxin A. Besides the ferric uptake regulatory protein Fur, which shuts off pvdS transcription under iron-replete conditions, no additional regulatory factor(s) controlling the pvdS promoter activity have been characterized so far. Here, we used the promoter region of pvdS as bait to tentatively capture, by DNA-protein affinity purification, P. aeruginosa proteins that are able to bind specifically to the pvdS promoter. This led to the identification and functional characterization of the LysR-like transcription factor CysB as a novel regulator of pvdS transcription. The CysB protein directly binds to the pvdS promoter in vitro and acts as a positive regulator of PvdS expression in vivo. The absence of a functional CysB protein results in about 50% reduction of expression of PvdS-dependent virulence phenotypes. Given the role of CysB as master regulator of sulfur metabolism, our findings establish a novel molecular link between the iron and sulfur regulons in P. aeruginosa. PMID:20370820

Imperi, Francesco; Tiburzi, Federica; Fimia, Gian Maria; Visca, Paolo

2010-06-01

142

Microstructural, mechanical and oxidation features of NiCoCrAlY coating produced by plasma activated EB-PVD  

NASA Astrophysics Data System (ADS)

NiCoCrAlY coatings produced by electron beam-physical vapor deposition (EB-PVD) have been extensively used as the oxidation resistance coatings or suitable bond coats in thermal barrier coating (TBC) system. However, the inherent imperfections caused by EB-PVD process degrade the oxidation resistance of the coatings. In the present work, NiCoCrAlY coatings were creatively produced by plasma activated electron beam-physical vapor deposition (PA EB-PVD). The novel coatings showed a terraced substructure on the surface of each grain due to the increased energy of metal ions and enhanced mobility of adatoms. Also a strong (1 1 1) crystallographic texture of ?/?' grains was observed. The toughness of the coatings got remarkably improved compared with the coatings deposited by conventional EB-PVD and the oxidation behavior at 1373 K showed that the novel coatings had excellent oxidation resistance. The possible mechanism was finally discussed.

He, Jian; Guo, Hongbo; Peng, Hui; Gong, Shengkai

2013-06-01

143

Thermometry at the nanoscale.  

PubMed

Non-invasive precise thermometers working at the nanoscale with high spatial resolution, where the conventional methods are ineffective, have emerged over the last couple of years as a very active field of research. This has been strongly stimulated by the numerous challenging requests arising from nanotechnology and biomedicine. This critical review offers a general overview of recent examples of luminescent and non-luminescent thermometers working at nanometric scale. Luminescent thermometers encompass organic dyes, QDs and Ln(3+)ions as thermal probes, as well as more complex thermometric systems formed by polymer and organic-inorganic hybrid matrices encapsulating these emitting centres. Non-luminescent thermometers comprise of scanning thermal microscopy, nanolithography thermometry, carbon nanotube thermometry and biomaterials thermometry. Emphasis has been put on ratiometric examples reporting spatial resolution lower than 1 micron, as, for instance, intracellular thermometers based on organic dyes, thermoresponsive polymers, mesoporous silica NPs, QDs, and Ln(3+)-based up-converting NPs and ?-diketonate complexes. Finally, we discuss the challenges and opportunities in the development for highly sensitive ratiometric thermometers operating at the physiological temperature range with submicron spatial resolution. PMID:22763389

Brites, Carlos D S; Lima, Patricia P; Silva, Nuno J O; Millán, Angel; Amaral, Vitor S; Palacio, Fernando; Carlos, Luís D

2012-08-21

144

Nanoscale surface photoreactions  

NASA Astrophysics Data System (ADS)

Subnanometer-scale properties of molecules and materials have become extremely important to the development of nanoscale and molecular electronics devices, including advanced biological and chemical sensors. The energies (i.e., wavelengths) at which the LSPRs of individual nanoparticles are excited varies depending on their size, thickness, and shape, all of which can be controlled synthetically. Photon-coupled scanning tunneling microscopy uses a total internal reflection scheme to couple light into a tunneling junction, generating this specific LSPR in individual Au and Ag nanoprisms. By controlling and coupling this specific excitation to molecular assemblies, the effective photoreactivities and photoconductances of organic molecules can be measured and manipulated. Nanoparticle synthesis methods were developed to produce nanoprisms with appropriate dimensions and homogeneity. Functionalization of the sample surface using alkanedithiols and p-terphenyl-4,4"-dithiol enabled the adsorption dispersion of nanoprisms onto substrates with high density yet minimal stacking. Insertion into self-assembled monolayers was used to arrange single molecules on Au{111} and Ag{111} nanoprisms for selective surface plasmonic enhancement. Scanning tunneling microscopy measurements were collected for molecules adsorbed on the dispersed nanoprisms. Photon STM will be used to monitor the photoactivities of molecules on these substrates, such as photocurrent, photoconductance, and photoreaction.

Wadsworth, Garrett Austin

145

Preparation of porous, chemically cross-linked, PVdF-based gel polymer electrolytes for rechargeable lithium batteries  

Microsoft Academic Search

This study reports the development of a new system of porous, chemically cross-linked, gel polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF–HFP) copolymer as a polymer matrix, polyethylene glycol (PEG) as a plasticizer, and polyethylene glycol dimethacrylate (PEGDMA) as a chemical cross-linking oligomer. The electrolytes are prepared by a combination of controlled evaporation and thermal polymerization of PEGDMA. PVdF–HFP\\/PEG\\/PEGDMA gel polymer

C. L Cheng; C. C Wan; Y. Y Wang

2004-01-01

146

Influence of bondcoat pre-treatment and surface topology on the lifetime of EB-PVD TBCs  

Microsoft Academic Search

In the present study two types of bondcoats (BC) were used, a NiCoCrAlY overlay coating produced by electron beam physical vapor deposition (EB-PVD) and a platinum aluminide diffusion coating (Ni,Pt)–Al. The coatings were deposited onto nickel-base IN100 and René142 substrates and were pre-treated in vacuum or Ar–H gas mixture prior to the deposition of an EB-PVD yttria partially stabilized zirconia

H. Lau; C. Leyens; U. Schulz; C. Friedrich

2003-01-01

147

Innovative steel strip coatings by means of PVD in a continuous pilot line: process technology and coating development  

Microsoft Academic Search

Based on PVD coating of already conventionally zinc-coated steel strip novel approaches to highly corrosion resistant zinc alloy coatings have been developed on a laboratory scale. In this paper, the successful up-scaling of such an approach to a continuous pilot line with line speed up to 60 m\\/min and strip width of 300 mm is reported. The PVD technology of

Bernd Schuhmacher; Christian Schwerdt; Ulf Seyfert; Otmar Zimmer

2003-01-01

148

Structural, thermal and ion transport studies of different particle size nanocomposite fillers incorporated PVdF-HFP hybrid membranes  

Microsoft Academic Search

Organic–inorganic hybrid membranes based on poly(vinylidene fluoride-co-hexa fluoropropylene) (PVdF-HFP)\\/sulfosuccinic acid were fabricated with different nanometer sizes of silica particles. Morphological images reveal the embedded ceramic filler over the membrane. Structural characterizations were made by FT-IR and XPS, ensure the inclusion of sulfosuccinic acid and silica into the PVdF-HFP polymer matrix. Sulfonic acid groups promote the IEC values and greater swelling

G. Gnana Kumar; Pil kim; Ae rhan kim; Kee suk Nahm; R. Nimma Elizabeth

2009-01-01

149

Rechargeable lithium battery employing a new ambient temperature hybrid polymer electrolyte based on PVK+PVdF–HFP (copolymer)  

Microsoft Academic Search

We describe here for the first time, our recent success in developing an ambient temperature Li+ conducting solid polymer electrolyte (SPE) using the concept of polymer alloying upon blending two thermoplastic polymers such as poly(vinylidene) fluoride-hexafluoropropylene (PVdF–HFP-copolymer) and poly(N-vinylcarbazole), PVK and achieved the room temperature electrolytic conductivity (?i) of 0.7×10?3S\\/cm for a typical composition of PVdF–HFP copolymer\\/PVK blend mixed with

M. S. Michael; S. R. S. Prabaharan

2004-01-01

150

Thermal shutdown behavior of PVdF-HFP based polymer electrolytes comprising heat sensitive cross-linkable oligomers  

Microsoft Academic Search

PVdF-HFP (polyvinylidenefluoride-hexafluoropropylene) polymer electrolytes comprising cross-linkable PEGDMA (polyethylene glycol dimethacrylate) oligomers with thermal shutdown characteristic have been developed. In contrast to the melting mechanism of polyolefin, this new polymer electrolyte possesses a thermal shutdown characteristic by a rapid cross-linking reaction of PEGDMA. The cross-linked PEGDMA network inside the PVdF-HFP matrix can provide the mechanical strength for the electrolytes, while the

C. L. Cheng; C. C. Wan; Y. Y. Wang; M. S. Wu

2005-01-01

151

The effect of F127 addition on the properties of PEGDA\\/PVdF cross-linked gel polymer electrolytes  

Microsoft Academic Search

The ternary polymer membranes consisting of poly(ethylene glycol) diacrylate (PEGDA), poly(vinylidene fluoride) (PVdF), and polyethylene oxide-co-polypropylene oxide-co-polyethylene oxide (PEO-PPO-PEO, F127) were prepared as the matrix of gel polymer electrolytes (GPEs) by a solvent controlled evaporation procedure. In the ternary system, the unraveled PVdF polymer chains are randomly mixed with the liquid PEGDA oligomer, which are entangled with themselves and the

Yan-Jie Wang; Dukjoon Kim

2008-01-01

152

Performance of PVD TiN, TiCN, and TiAlN coated cemented carbide tools in turning  

Microsoft Academic Search

Ion-plated PVD TiN, TiCN, and high-ionization sputtered PVD TiAlN coatings were deposited on WC–6wt%Co hardmetal inserts. Microstructural and mechanical properties of the coatings and substrate were characterized. Coated tools were evaluated in turning of Inconel 718, medium carbon SAE 1045 steel, and ductile iron at low and high cutting speeds. TiAlN coated tools showed the best metalcutting performance, followed by

P. C Jindal; A. T Santhanam; U Schleinkofer; A. F Shuster

1999-01-01

153

Thermal conductivity of EB-PVD thermal barrier coatings evaluated by a steady-state laser heat flux technique  

Microsoft Academic Search

The thermal conductivity of electron beam-physical vapor deposited (EB-PVD) ZrO2–8 wt.%Y2O3 thermal barrier coatings was determined by a steady-state laser heat flux technique. Thermal conductivity change kinetics of the EB-PVD ceramic coatings were also obtained in real time, at high temperatures, under the laser high heat flux, long-term test conditions. The thermal conductivity increase due to micro-pore sintering and the

Dongming Zhu; Robert A. Miller; Ben A. Nagaraj; Robert W. Bruce

2001-01-01

154

Enhancement of the punch pin durability induced by the PVD coating in production process of the automotive inner pipe  

Microsoft Academic Search

This experimental studies were carried out in order to understand the effects of the PVD coating and the UNSM treatment of\\u000a HSS55 (high speed steel 55) during the production of the automotive inner pipe by the plastic deformation of S45C. The field\\u000a test and the SEM images revealed that the PVD coating is necessary in spite of the high compressive

Chang-Min Suh; Sang-Yeob Oh; Young-Sik Pyun

2010-01-01

155

Functional expression and activity of the recombinant antifungal defensin PvD1r from Phaseolus vulgaris L. (common bean) seeds  

PubMed Central

Background Defensins are basic, cysteine-rich antimicrobial peptides that are important components of plant defense against pathogens. Previously, we isolated a defensin, PvD1, from Phaseolus vulgaris L. (common bean) seeds. Results The aim of this study was to overexpress PvD1 in a prokaryotic system, verify the biologic function of recombinant PvD1 (PvD1r) by comparing the antimicrobial activity of PvD1r to that of the natural defensin, PvD1, and use a mutant Candida albicans strain that lacks the gene for sphingolipid biosynthesis to unravel the target site of the PvD1r in C. albicans cells. The cDNA encoding PvD1, which was previously obtained, was cloned into the pET-32 EK/LIC vector, and the resulting construct was used to transform bacterial cells (Rosetta Gami 2 (DE3) pLysS) leading to recombinant protein expression. After expression had been induced, PvD1r was purified, cleaved with enterokinase and repurified by chromatographic steps. N-terminal amino acid sequencing showed that the overall process of the recombinant production of PvD1r, including cleavage with the enterokinase, was successful. Additionally, modeling revealed that PvD1r had a structure that was similar to the defensin isolated from plants. Purified PvD1 and PvD1r possessed inhibitory activity against the growth of the wild-type pathogenic yeast strain C. albicans. Both defensins, however, did not present inhibitory activity against the mutant strain of C. albicans. Antifungal assays with the wild-type C. albicans strains showed morphological changes upon observation by light microscopy following growth assays. PvD1r was coupled to FITC, and the subsequent treatment of wild type C. albicans with DAPI revealed that the labeled peptide was intracellularly localized. In the mutant strain, no intracellular labeling was detected. Conclusion Our results indicate that PvD1r retains full biological activity after recombinant production, enterokinase cleavage and purification. Additionally, our results from the antimicrobial assay, the microscopic analysis and the PvD1r-FITC labeling assays corroborate each other and lead us to suggest that the target of PvD1 in C. albicans cells is the sphingolipid glucosylceramide.

2014-01-01

156

Applications of multilayer optics  

NASA Astrophysics Data System (ADS)

Recent development of multilayer mirror and its applications in extreme ultraviolet (EUV), soft X-ray ranges in China was reviewed in this paper. Three types of multilayer mirrors were developed with special performance for dense plasma diagnostics, EUV astronomical observation. Firstly, dual-periodic W/B 4C multilayer mirror was designed for Kirkpatrick-Baez (K-B) microscopy working at TiK? line (4.75 keV), which is highly reflective both at hard X-ray (CuK? line at 8.05 keV) and soft X-ray (4.75 keV). Using this mirror, the K-B system can be aligned conveniently in air using hard X-ray instead of in vacuum. The second mirror is aperiodic Mg/SiC multilayer, also a bi-functional mirror with high reflectivity for He-II emission line (30.4 nm) but suppressing He-I emission line (58.4 nm) in astronomy observation, which will replace the traditional combination of periodic multilayer and the fragile film filter. This will be more safe in satellite launching. The third mirror is Mo/Si periodic multilayer, depositing on a parabolic substrate with diameter of 230 mm, which is designed for EUV telescope for imaging of solar corona by selecting Fe-XII emission (19.5 nm). The uniformity of lateral layer thickness distribution is within ±0.3% along the diameter of mirror, measured by X-ray reflectometry. The measured peak reflectivity is 42% at the wavelength of 19.5 nm. All these multilayer mirrors were prepared by using magnetron sputtering system in our group.

Wang, Zhanshan; Zhu, Jingtao; Mu, Baozhong; Zhang, Zhong; Wang, Fengli; Xu, Jing; Li, Wenbin; Chen, Lingyan

2010-11-01

157

Stereometry specification of anodised and PVD coated surface of aluminium alloy  

Microsoft Academic Search

Purpose: The aim of the work is to present the influence of casting method and anodic treatment parameters on properties, thickness and structure of an anodic layer with (PVD) physical vapour deposition method achieved TiN layer formed on aluminum casting alloys. Design\\/methodology\\/approach: Investigations were carried out on the laser profile measurement gauge MicroProf from company FRT, abrasive wear test was

J. Konieczny; K. Labisz; J. Wieczorek; L. A. Dobrzañski

158

EB-PVD processing of pyrochlore-structured La 2Zr 2O 7-based TBCs  

Microsoft Academic Search

New ceramic thermal barrier coating (TBC) compositions superior to state-of-the-art PYSZ material are considered to overcome the problems related to phase stability and service-induced sintering within the columnar feather-like structure of current EB-PVD TBCs. Among those candidates for gas turbine applications, the pyrochlore-structure based TBCs, e.g. undoped and RE-oxide doped La2Zr2O7 offer very attractive properties. This work describes the fabrication

B Saruhan; P Francois; K Fritscher; U Schulz

2004-01-01

159

Micro-abrasive wear of PVD duplex and single-layered coatings  

Microsoft Academic Search

A micro-abrasive wear test has been used to evaluate the wear resistance of duplex coatings, consisting of plasma nitriding followed by PVD coating. Two duplex coatings were investigated: TiAlN and TiN. Single-layered TiAlN and TiN coatings were also tested to evaluate the effect of the duplex treatment on wear resistance. Prior to wear testing, coating properties were evaluated by hardness,

J. C. A. Batista; A. Matthews; C. Godoy

2001-01-01

160

Novel load-carrying layers to support low-friction PVD coatings  

Microsoft Academic Search

Five different materials have been studied with respect to their load-carrying capacity together with PVD coatings. The materials were mild carbon steel, hardened and annealed ball bearing steel, a thick electro-deposited Ni coating, and plasma-sprayed alumina coatings with and without the pores and cracks sealed with electro-deposited Ni. The two latter materials have not previously been studied in this respect.

Richard Westergård; Fredrik Svahn; Urban Wiklund

2003-01-01

161

WEAR OF PVD COATED TOOLS IN MILLING AFFECTED BY THE GRAIN SIZE OF CEMENTED CARBIDE SUBSTRATES  

Microsoft Academic Search

To explain the coating and substrate wear behaviour, when applying cemented car- bide (HM) tools with different grain sizes in milling, two variations of HM inserts, a fine- and an ultra-fine-grained one were coated with the same PVD AlTiN film. These inserts were examined by nanoindentations and impact tests concerning me- chanical properties and by milling experiments regarding wear. The

K.-D. Bouzakis; M. Pappa; S. Gerardis; G. Katirtzoglou; E. Lili; N. Michailidis; K. Efstathiou; G. Erkens

162

Influence of substrate material on oxidation behavior and cyclic lifetime of EB-PVD TBC systems  

Microsoft Academic Search

EB-PVD NiCoCrAlY\\/P-YSZ TBCs on several polycrystalline, directionally solidified, and single crystalline (SX) substrate alloys were thermally cycled at 1100°C. TBC spallation does not correlate solely to TGO thickness, but depends also very much on the substrate alloy. The longest lifetimes are achieved on Hf-containing alloys while SX alloys suffer from early TBC spallation. The formation of the thermally grown oxide

U Schulz; M Menzebach; C Leyens; Y. Q Yang

2001-01-01

163

Microstructure and texture of EB-PVD TBCs grown under different rotation modes  

Microsoft Academic Search

The role of vapor incidence pattern (VIP) on the microstructure and texture of thermal barrier coatings (TBCs) produced by electron-beam physical vapor deposition (EB-PVD) is examined. Two distinct VIPs are induced by proper design of the substrate rotation mode. One is the sunrise–sunset pattern typical of conventional deposition on the curved face of a rotating cylinder (mode A), and the

U. Schulz; S. G. Terry; C. G. Levi

2003-01-01

164

Effect of thermal exposure on stress distribution in TGO layer of EB-PVD TBC  

Microsoft Academic Search

The stress distributions in thermally grown oxide (TGO) layer of electron beam enhanced physical vapor deposited thermal barrier coating (EB-PVD TBC) before and after thermal exposure are measured by photo-stimulated luminescence spectrum. It is found that the stress in the TGO layer in original state is an order of ~3 GPa. It increases from 3.0–3.9 GPa with the increase of

T Tomimatsu; S Zhu; Y Kagawa

2003-01-01

165

Influence of porosity on hardness and Young's modulus of nanoporous EB-PVD TBCs by nanoindentation  

Microsoft Academic Search

The hardness and Young's modulus of ZrO2–4 mol% Y2O3 coating layers fabricated by EB-PVD are characterized using a nanoindentation technique. Coatings consist of porous, aligned columnar structure. The porosity of the coatings increased with increasing substrate rotation speed during deposition. The hardness and Young's modulus showed a significant dependence on the porosity and a strong anisotropy due to the columnar

Byung-Koog Jang; Hideaki Matsubara

2005-01-01

166

Effect of morphology on thermal conductivity of EB-PVD PYSZ TBCs  

Microsoft Academic Search

Partially yttria stabilized zirconia (PYSZ) based thermal barrier coatings (TBC) manufactured by electron beam-physical vapour deposition (EB-PVD) protect turbine blades, working under severe service conditions in aero engines and stationary turbines. These coatings show a high strain tolerance relying on their unique morphology which is comprised of weakly bonded, preferred-oriented columns, voids between feather-like sub-columns and, finally, of intra-columnar closed

A. Flores Renteria; B. Saruhan; U. Schulz; H.-J. Raetzer-Scheibe; J. Haug; A. Wiedenmann

2006-01-01

167

Thermocyclic behavior of variously stabilized EB-PVD thermal barrier coatings  

Microsoft Academic Search

The demand for increasing gas inlet temperatures in modern gas turbines up to 1,500 C and above is the main reason for the need for more reliable thermal barrier coatings. New ceramics should provide higher phase stability and better resistance against chemical attack by pollutants in the combustion gas. Electron beam-- physical vapor deposition (EB-PVD) processed, ZrOâ-based TBCs were generated

U. Schulz; K. Fritscher; M. Peters

1997-01-01

168

Ionic liquid–polymer gel electrolytes based on morpholinium salt and PVdF(HFP) copolymer  

Microsoft Academic Search

New ionic liquid–polymer gel electrolytes (IPGEs) are prepared from N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide (Mor1,2TFSI) and poly(vinylidene fluoride)-hexafluoropropylene copolymer (PVdF(HFP)). To investigate the effect of propylene carbonate (PC) on the ionic conductivity of the IPGEs, the preparation methods are roughly divided into two groups according to the presence or absence of PC. The ionic conductivity for each IPGE is measured with increasing temperature

Ki-Sub Kim; Seung-Yeob Park; Sukjeong Choi; Huen Lee

2006-01-01

169

Electro chemical properties of porous PVdF-HFP membranes prepared with different nonsolvents  

Microsoft Academic Search

Porous poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) membranes were prepared by solvent–nonsolvent evaporation technique. Morphology and porosity of the membranes were varied with different nonsolvents and had an effect on electrochemical properties. The porous membranes were functionalized with different liquid electrolyte solutions such as p-toluene sulfonic acid\\/phosphoric acid\\/sulfuric acid. Maximum electrolyte uptake and minimal electrolyte leakage were tailored by the optimized porosity of

G. Gnana Kumar; Kee Suk Nahm; R. Nimma Elizabeth

2008-01-01

170

Structure, transport properties and interfacial stability of PVdF\\/HFP electrolytes containing modified inorganic filler  

Microsoft Academic Search

Gel polymer electrolyte membranes composed of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) and surface modified aluminum or titanium oxide were prepared according to the so-called Bellcore process. Modifications were done by impregnating ceramic powder with 1–8% sulphuric acid aqueous solutions. Filler grain size varied from 10 to 12?m. The membranes were conditioned in liquid electrode—1mol\\/l LiClO4 in PC.The ionic conductivity of polymer membrane

M. Stolarska; L. Niedzicki; R. Borkowska; A. Zalewska; W. Wieczorek

2007-01-01

171

Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) based composite electrolytes for lithium batteries  

Microsoft Academic Search

The composite polymer electrolyte (CPE) membranes, comprising of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), aluminum oxyhydroxide, (AlO[OH]n) of two different particle sizes 7?m\\/14nm and LiN(CF3SO2)2 as lithium salt were prepared using solution casting technique. The prepared membranes were subjected to XRD, impedance spectroscopy, compatibility and transport number studies. The incorporation of nanofiller greatly enhanced the ionic conductivity and the compatibility of the composite

A. Manuel Stephan; Kee Suk Nahm; M. Anbu Kulandainathan; G. Ravi; J. Wilson

2006-01-01

172

Microporous PVdF-HFP based gel polymer electrolytes reinforced by PEGDMA network  

Microsoft Academic Search

We have successfully developed a new process to prepare microporous poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer based gel electrolyte with polyethylene glycol dimethacrylate (PEGDMA) network without the need for extraction process. Microporous structure in polymer matrix is achieved by solvent controlled evaporation from solution containing a copolymer in a mixture of volatile solvent and nonsolvent. The high tensile modulus and better flexibility

C. L. Cheng; C. C. Wan; Y. Y. Wang

2004-01-01

173

Lithium ion conduction in plasticized PMMA–PVdF polymer blend electrolytes  

Microsoft Academic Search

Polymer electrolyte membranes comprising poly(vinylidene fluoride) (PVdF), poly(methylmethacrylate) (PMMA), LiClO4 and DMP were prepared. Structural characterization was carried out on the polymer electrolyte thin film using XRD. The complex formation of polymer and salt has been confirmed by XRD and FT-IR spectral studies. The ac conductivity studies were performed to evaluate the ambient temperature conductivity of the polymer electrolyte membranes.

S Rajendran; O Mahendran; R Kannan

2002-01-01

174

Investigations on PMMA-PVdF polymer blend electrolyte with esters of dibenzoic acids as plasticizers  

Microsoft Academic Search

Plasticizers can be used to change the electrical and mechanical properties of polymer electrolytes by reducing the degree\\u000a of crystallinity and lowering the glass transition temperature. The transport properties of gel type ionic conducting membranes\\u000a consisting of poly (methyl methacrylate) (PMMA), poly (vinylidene fluriode) (PVdF), Lithium perchlorate (LiClO4) and dioctyl phthalate (DOP), dibutyl phthalate (DBP), dimethyl phthalate (DMP) or diethyl

O. Mahendran; S. Y. Chen; Y. W. Chen-Yang; J. Y. Lee; S. Rajendran

2005-01-01

175

Oxidation-induced failure of EB-PVD thermal barrier coatings  

Microsoft Academic Search

Oxidation-induced failure of EB-PVD thermal barrier coatings (TBC) deposited on a single-crystal superalloy with a platinum aluminide bond coat has been studied in order to determine the specific mechanisms leading to TBC spallation. Cyclic oxidation tests performed at 1150°C show that failure of the TBC occurs when the alumina scale, growing at the bond coat–TBC interface, attains its critical thickness.

V. K Tolpygo; D. R Clarke; K. S Murphy

2001-01-01

176

Measurements of the thermal gradient over EB-PVD thermal barrier coatings  

Microsoft Academic Search

Conventional two-layered structure thermal barrier coatings (TBCs), graded thermal barrier coatings (GTBCs) and graded thermal barrier coatings with micropores were prepared onto superalloy DZ22 tube by electron beam physical vapor deposition (EB-PVD). Thermal gradient of the TBCs was evaluated by embedding two thermal couples in the surfaces of the tube and the top coat at different surrounding temperatures with and

Dongbo Zhang; Shengkai Gong; Huibin Xu; Hongbo Guo

2003-01-01

177

Miniaturized bend tests on partially stabilized EB-PVD ZrO 2 thermal barrier coatings  

Microsoft Academic Search

The elastic properties of thermal barrier coatings (TBCs) are important for modelling the lifetime of these coatings. A new test setup has been developed to measure the system modulus of electron-beam enhanced physical vapour deposited (EB-PVD) TBC coatings by miniaturized bend tests.Due to the brittleness, low stiffness and small thickness of the top coat and its complex microstructure, it is

Carolin Pfeiffer; Ernst Affeldt; Mathias Göken

2011-01-01

178

Galvanic corrosion properties of differently PVD-treated magnesium die cast alloy AZ91  

Microsoft Academic Search

Different types of PVD coatings and plasma treatments were applied for the surface treatment of magnesium die cast alloy AZ91 specimens. The different types of surface treatment were all developed by the authors and the fundamental properties are described elsewhere. The coating systems were:•9 ?m CrN hard coating•3 ?m TiN coating•0.5 ?m plasma anodisation layer and 3 ?m Al2O3 coatingThe

H. Hoche; C. Blawert; E. Broszeit; C. Berger

2005-01-01

179

Effect of Bond Coat Materials on Thermal Fatigue Failure of EB-PVD Thermal Barrier Coatings  

Microsoft Academic Search

Effect of MCrAlY bond coat alloy systems on thermal fatigue failure of thermal barrier coatings (TBCs) was investigated, where the TBC specimen consisted of Ni-based superalloy IN738LC substrate, bond coat, and 8 wt.% Y2O3-stabilized ZrO2 (YSZ) top coat. The top coat was fabricated by EB-PVD method with 250 mum in thickness. Three kinds of MCrAlY alloys were studied as the

Satoshi Yamagishi; Masakazu Okazaki; Motoki Sakaguchi; Hideaki Matsubara

2008-01-01

180

Direct observations of confined layer slip in Cu/Nb multilayers.  

PubMed

In situ nanoindentation of a 30 nm Cu/20 nm Nb multilayer film in a transmission electron microscope revealed confined layer slip as the dominant deformation mechanism. Dislocations were observed to nucleate from the Cu-Nb interfaces in both layers. Dislocation glide was confined by interfaces to occur within each layer, without transmission across interfaces. Cu and Nb layers co-deformed to large plastic strains without cracking. These microscopy observations provide insights in the unit mechanisms of deformation, work hardening, and recovery in nanoscale metallic multilayers. PMID:23072907

Li, Nan; Wang, Jian; Misra, Amit; Huang, Jian Yu

2012-10-01

181

Microstructural variations in Cu/Nb and Al/Nb nanometallic multilayers  

SciTech Connect

Miscible (Al/Nb) and immiscible (Cu/Nb) nanometallic multilayer systems were characterized by means of transmission electron microscopy techniques, primarily by automated crystallographic orientation mapping, which allows for the resolution of crystal structures and orientations at the nanoscale. By using this technique, distinctive Nb orientations in relation to the crystallographic state of the Al and Cu layer structures can be observed. Specifically, the Al and Cu layers were found to consist of amorphous, semi-amorphous, and crystalline regions, which affect the overall multilayer microstructure.

Polyakov, M. N.; Hodge, A. M. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, California 90089 (United States)] [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Courtois-Manara, E.; Wang, D.; Kuebel, C. [Institute of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany)] [Institute of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Chakravadhanula, K. [Institute of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany) [Institute of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Helmholtz Institute Ulm, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2013-06-17

182

Nanomechanical study of thin film nanocomposite and PVD thin films on polymer substrates for optical applications  

NASA Astrophysics Data System (ADS)

The mechanical properties of ultrathin (<120 nm) films differ substantially from the bulk properties of the material and are also strongly substrate dependent. We compare the properties of two differing film systems; a high particle loading nanocomposite of silica and a multiple layer physical vapour deposition (PVD) coating by nanoindentation, nano-scratch and nano-impact followed by structural analysis. The work is undertaken on hardcoated polymer substrates and uses two types of anti-reflection coatings as test systems. The nanocomposite film comprises of a high (>50%) loading of silica nanoparticles in an inorganic binder, which demonstrates significant flex and elastic recovery whereas PVD films are subject to brittle failure even at low applied loads. Failure of the nanocomposite film, with the exception of minor plastic deformation, does not occur until the underlying substrate fails. Although the PVD film has a greater hardness than the nanocomposite, failure occurs at lower loads due to a number of toughness reducing factors including reduced modulus, modulus mismatch with the substrate and film thickness. The resistance of ultrathin films to external mechanical stresses is therefore related to a number of factors and not simply to film hardness, the most important of which are film structure and film mechanical matching to the substrate.

Moghal, Jonathan; Bird, Andrew; Harris, Adrian H.; Beake, Ben D.; Gardener, Martin; Wakefield, Gareth

2013-12-01

183

Magnetic multilayer interface anisotropy  

SciTech Connect

Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependent FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers is contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the ransition temperature.

Pechan, M.J.

1992-01-01

184

Multilayered Graphene in Microwaves  

NASA Astrophysics Data System (ADS)

We report on the experimental study of electromagnetic (EM) properties of multilayered graphene in Ka-band synthesized by catalytic chemical vapor deposition (CVD) process in between nanometrically thin Cu catalyst film and dielectric (SiO2) substrate. The quality of the produced multilayered graphene samples were monitored by Raman spectroscopy. The thickness of graphene films was controlled by atomic force microscopy (AFM) and was found to be a few nanometers (up to 5 nm). We discovered, that the fabricated graphene provided remarkably high EM shielding efficiency caused by absorption losses at the level of 35-43% of incident power. Being highly conductive at room temperature, multi-layer graphene emerges as a promising material for manufacturing ultrathin microwave coatings to be used in aerospace applications.

Kuzhir, P.; Volynets, N.; Maksimenko, S.; Kaplas, T.; Svirko, Yu.

2013-05-01

185

NANOSCALE BIOSENSORS IN ECOSYSTEM EXPOSURE RESEARCH  

EPA Science Inventory

This powerpoint presentation presented information on nanoscale biosensors in ecosystem exposure research. The outline of the presentation is as follows: nanomaterials environmental exposure research; US agencies involved in nanosensor research; nanoscale LEDs in biosensors; nano...

186

The effects of heat treatment and gas atmosphere on the thermal conductivity of APS and EB-PVD PYSZ thermal barrier coatings  

Microsoft Academic Search

The effects of heat treatment and gas atmosphere on thermal conductivity of atmospheric plasma sprayed (APS) and electron beam physical vapor deposited (EB-PVD) partially Y2O3 stabilized ZrO2 (PYSZ) thermal barrier coatings (TBCs) were investigated. Two-layer samples that had an EB-PVD coating deposited on bond coated nickel-base superalloy IN625 substrates, free-standing APS and EB-PVD coatings as well as a quasi-free-standing EB-PVD

H.-J. Rätzer-Scheibe; U. Schulz

2007-01-01

187

Nanoscale inhomogeneities in thermoresponsive polymers.  

PubMed

This article highlights the occurrence and nature of nanoscale inhomogeneities in thermoresponsive polymers and focuses on different experimental techniques for their observation and characterization. Such inhomogeneities can be regarded as nanoscopic domains of collapsed polymer segments (or of a small number of unimers), which provide a nonpolar, hydrophobic interior. Continuous wave (CW) electron paramagnetic resonance (EPR) spectroscopy on amphiphilic reporter molecules (spin probes) as an intrinsically local technique is particularly emphasized. In combination with different ensemble-averaging methods, it provides a holistic understanding of the often inhomogeneous nanoscale processes during the temperature-induced collapse of a thermoresponsive polymer. PMID:23169221

Kurzbach, Dennis; Junk, Matthias J N; Hinderberger, Dariush

2013-01-25

188

Nanoscale Science and Engineering Education (NSEE)  

NSF Publications Database

[A] Nanoscale Informal Science Education (NISE): This effort is intended to foster public awareness, engagement, and understanding of nanoscale science, engineering, and technology through establishment of a Network, a national infrastructure that links science museums and other informal science education organizations with nanoscale science and engineering research organizations. Specifically, the NISE component will establish a national infrastructure that links science museums and other ...

189

Center for Nanoscale Science and Technology  

National Institute of Standards and Technology Data Gateway

NIST Center for Nanoscale Science and Technology (Program website, free access)   Currently there is no database matching your keyword search, but the NIST Center for Nanoscale Science and Technology website may be of interest. The Center for Nanoscale Science and Technology enables science and industry by providing essential measurement methods, instrumentation, and standards to support all phases of nanotechnology development, from discovery to production.

190

Design and synthesis of bimetallic electrocatalyst with multilayered Pt-skin surfaces.  

SciTech Connect

Advancement in heterogeneous catalysis relies on the capability of altering material structures at the nanoscale, and that is particularly important for the development of highly active electrocatalysts with uncompromised durability. Here, we report the design and synthesis of a Pt-bimetallic catalyst with multilayered Pt-skin surface, which shows superior electrocatalytic performance for the oxygen reduction reaction (ORR). This novel structure was first established on thin film extended surfaces with tailored composition profiles and then implemented in nanocatalysts by organic solution synthesis. Electrochemical studies for the ORR demonstrated that after prolonged exposure to reaction conditions, the Pt-bimetallic catalyst with multilayered Pt-skin surface exhibited an improvement factor of more than 1 order of magnitude in activity versus conventional Pt catalysts. The substantially enhanced catalytic activity and durability indicate great potential for improving the material properties by fine-tuning of the nanoscale architecture.

Wang, C.; Chi, M.; Li, D.; Strmcnik, D.; van der Vliet, D.; Wang, G.; Komanicky, V.; Chang, K.-C.; Paulikas, A. P.; Tripkovic, D.; Pearson, J.; More, K. L.; Markovic, N. M.; Stamenkovic, V. R. (Materials Science Division); (ORNL.); (Univ. of Pittsburgh)

2011-01-01

191

Design and Synthesis of Bimetallic Electrocatalyst with Multilayered Pt-Skin Surfaces  

SciTech Connect

Advancement in heterogeneous catalysis relies on the capability of altering material structures at the nanoscale, and that is particularly important for the development of highly active electrocatalysts with uncompromised durability. Here, we report the design and synthesis of a Pt-bimetallic catalyst with multilayered Pt-skin surface, which shows superior electrocatalytic performance for the oxygen reduction reaction (ORR). This novel structure was first established on thin film extended surfaces with tailored composition profiles and then implemented in nanocatalysts by organic solution synthesis. Electrochemical studies for the ORR demonstrated that after prolonged exposure to reaction conditions, the Pt-bimetallic catalyst with multilayered Pt-skin surface exhibited an improvement factor of more than 1 order of magnitude in activity versus conventional Pt catalysts. The substantially enhanced catalytic activity and durability indicate great potential for improving the material properties by fine-tuning of the nanoscale architecture.

Wang, Chao [Argonne National Laboratory (ANL); Chi, Miaofang [ORNL; Li, Dongguo [Argonne National Laboratory (ANL); Strmcnik, Dusan [Argonne National Laboratory (ANL); Van der Vliet, Dennis [Argonne National Laboratory (ANL); Wang, Guofeng [Indiana University and Purdue University; Komanicky, Vladimir [Argonne National Laboratory (ANL); Chang, Kee-Chul [Argonne National Laboratory (ANL); Paulikas, Arvydas [Argonne National Laboratory (ANL); Tripkovic, Dusan [Argonne National Laboratory (ANL); Pearson, John [Argonne National Laboratory (ANL); More, Karren Leslie [ORNL; Markovic, Nenad [Argonne National Laboratory (ANL); Stamenkovic, Vojislav [Argonne National Laboratory (ANL)

2011-01-01

192

Nanoconstruction by welding individual metallic nanowires together using nanoscale solder  

NASA Astrophysics Data System (ADS)

This work presents a new bottom-up nanowelding technique enabling building blocks to be assembled and welded together into complex 3D nanostructures using nanovolumes of metal solder. The building blocks of gold nanowires, (Co72Pt28/Pt)n multilayer nanowires, and nanosolder Sn99Au1 alloy nanowires were successfully fabricated by a template technique. Individual metallic nanowires were picked up and assembled together. Conductive nanocircuits were then welded together using similar or dissimilar nanosolder material. At the weld sites, nanoscale volumes of a chosen metal are deposited using nanosolder of a sacrificial nanowire, which ensures that the nanoobjects to be bonded retain their structural integrity. The whole nanowelding process is clean, controllable and reliable, and ensures both mechanically strong and electrically conductive contacts.

Peng, Y.; Cullis, A. G.; Inkson, B. J.

2010-07-01

193

Advanced STEM Characterization of Nanoscale Materials  

NASA Astrophysics Data System (ADS)

Nanoscale materials are the key structures in determining the properties of many technologically-important materials. Two such important nanoscale materials for different technological applications are investigated in this dissertation. They are: Fischer-Tropsch (FT) catalysts and irradiated metallic bi-layers. Catalytic activity depends on the structural parameters such as size, shape, and distribution on support. On the other hand, the radiation resistance of the model metallic multi-layers is influenced by the presence of interphase, phase-boundaries, and grain-boundaries. The focus of this dissertation is to use different TEM and STEM techniques to understand the structure of these materials. This dissertation begins with a review of the microscopy techniques used in the experiments. Then, in the next two chapters, literature review followed by results and discussions on the two above-mentioned nano materials are presented. Future research directions are included in the concluding chapter. To obtain three-dimensional morphological information of the FT catalysts during reduced/active state, STEM tomography is used. The oxidized state and reduced state is clarified by using STEM-EELS (in the form of spectrum imaging). We used a special vacuum transfer tomography holder and ex-situ gas assembly for reduction, and the reduction parameters are optimized for complete reduction. It was observed that the particle was reduced with 99.99% H2, and at 400°C for 15 minutes. The tomographic results in before-reduction condition depict that the Co-oxide particles are distributed randomly inside the alumina support. After reduction, the tomogram reveals that metallic Co nucleated and sintered towards the surface of the alumina support. The overall metallic Co distribution shows an outward segregation by subsurface diffusion mechanism. In the study of metallic bi-layer, He-irradiated gold twist grain boundary (AuTGB) was chosen as it is one of the least-studied systems in the area of model metallic multi-layers materials. Traditional TEM techniques such as two-beam imaging, weak beam imaging, and through-focal series have been applied to characterize the dislocation network and He bubble distribution. STEM Z-contrast imaging has also been applied to characterize the dislocation network and He bubble distribution. The TGB is found to consist of grid (square, rectangular) of screw dislocations with a line direction along <110> and with Burgers vector1/2a<110>. The He bubble distribution is found to be random across the thickness. The results showed that, because of STEM's characteristic dependence on atomic number, STEM imaging reduces the post-processing of images and provides 3D information about distribution of the radiation damage which is unobtainable by TEM. In summary, this dissertation makes important contributions to the knowledge of FT catalyst by providing direct, reliable representation of 3D structure of a FT catalyst after reduction and irradiated metallic-bilayer knowledge base by presenting new results which will help in designing new materials and fabrication techniques.

Dey, Sanchita

194

Correlation between constitution, properties and machining performance of TiN\\/ZrN multilayers  

Microsoft Academic Search

A concept for wear protective coatings on saw blades for metal cutting applications based on nanoscale titanium nitride\\/zirconium nitride (TiN\\/ZrN) multilayers is presented, which comprises the adjustment of columnar morphology for the cavities between the columns being used as a reservoir of cooling lubricants. The challenge consisted in optimizing the deposition conditions such that adhesion is increased to values that

S. Ulrich; C. Ziebert; M. Stüber; E. Nold; H. Holleck; M. Göken; E. Schweitzer; P. Schloßmacher

2004-01-01

195

Enhancing mechanical and tribological performance of multilayered CrN\\/ZrN coatings  

Microsoft Academic Search

The CrN\\/ZrN multilayered coatings with nanoscale bilayer period were synthesized at different substrate rotary speeds (4–11 rpm) and reaction gas flows in an unbalances reactive dc magnetron sputter chamber. XRD, AES, XPS, Nano indenter and tribometer were employed to investigate the influence of substrate rotary speed, species of reaction gases and flows on microstructure, mechanical and tribological properties of the coatings.

J. J. Zhang; M. X. Wang; J. Yang; Q. X. Liu; D. J. Li

2007-01-01

196

QQ: Nanoscale Timing and Profiling  

Microsoft Academic Search

QQ is a tool for timing and memory profiling capable of nanoscale time resolution. Designed to minimize both learning curve and impact on the profiled code, it is plat- form independent and usable with sequential, distributed, and parallel programs. QQ is invoked via embedded func- tion calls, and outputs event and timing records in a com- pact binary format. These

James Frye; James G. King; Christine J. Wilson; Frederick C. Harris Jr.

2005-01-01

197

Waveguiding in nanoscale metallic apertures  

Microsoft Academic Search

We study the optical properties of subwavelength metallic waveguides made of nanoscale apertures in a metal. We develop analytical expressions for the fundamental optical modes in apertures. The results are in excellent agreement with finite element calculations. This model provides a physical understanding of the role of non-perfect metallic walls, and of the shape and size of the apertures. They

Stéphane Collin; Fabrice Pardo; Jean-Luc Pelouard

2007-01-01

198

Computational Spectroscopy for Nanoscale Photovoltaics  

NASA Astrophysics Data System (ADS)

Nanoscale photovoltaic (PV) systems employ nanomaterial interfaces to dissociate bound excitons formed upon sunlight absorption. This mechanism results in a correlated electron, hole, and exciton interface dynamics whose accurate determination is challenging both theoretically and experimentally. In this talk, I will discuss approaches available to compute and combine relevant spectroscopic quantities to predict efficient nanoscale PV systems. Further, I will present our recent work on two novel families of nanoscale PV devices based on: 1) Nanocarbon materials, achieving 1.3% efficiency, tunable infra-red optical absorption, and superior photostability compared to organic solar cells 2) Two-dimensional monolayer semiconductors such as Graphene-BN and MoS2, capable of absorbing a significant fraction of sunlight within just 10nm, and showing tunable absorption, band offsets, and power conversion efficiency (PCE).[4pt] In closing, I will discuss the errors and necessary accuracy in predicting PCE from first-principles calculations, and propose a suitable figure of merit to quantify absorption solar-matchedness to be used in large-scale searches of nanoscale PV materials.

Bernardi, Marco

2013-03-01

199

Nanoscale wicking methods and devices  

NASA Technical Reports Server (NTRS)

A fluid transport method and fluid transport device are disclosed. Nanoscale fibers disposed in a patterned configuration allow transport of a fluid in absence of an external power source. The device may include two or more fluid transport components having different fluid transport efficiencies. The components may be separated by additional fluid transport components, to control fluid flow.

Zhou, Jijie (Inventor); Bronikowski, Michael (Inventor); Noca, Flavio (Inventor); Sansom, Elijah B. (Inventor)

2011-01-01

200

Structural transitions in nanoscale systems  

Microsoft Academic Search

In this work I investigate three different materials: nanoscale carbon systems, ferrofluid systems, and molecular-electronic devices. In particular, my study is focused on the theoretical understanding of structural changes and the associated electronic, mechanical, and magnetic properties of these materials. To study the equilibrium packing of fullerenes in carbon nanotube peapods optimization techniques were applied. In agreement with experimental measurements,

Mina Yoon

2004-01-01

201

Interface of Nanoscale Inclusion Chemistry.  

National Technical Information Service (NTIS)

This review presents a selected review of nanoscale inclusion chemistry using 3-D periodic hosts with an emphasis on optical properties. Inclusion chemistry is defined in the context of the above discussion as the interaction between a 3-D host surfaces w...

G. D. Stucky

1992-01-01

202

Sensing at the nanoscale  

NASA Astrophysics Data System (ADS)

The merits of nanostructures in sensing may seem obvious, yet playing these attributes to their maximum advantage can be a work of genius. As fast as sensing technology is improving, expectations are growing, with demands for cheaper devices with higher sensitivities and an ever increasing range of functionalities and compatibilities. At the same time tough scientific challenges like low power operation, noise and low selectivity are keeping researchers busy. This special issue on sensing at the nanoscale with guest editor Christofer Hierold from ETH Zurich features some of the latest developments in sensing research pushing at the limits of current capabilities. Cheap and easy fabrication is a top priority. Among the most popular nanomaterials in sensing are ZnO nanowires and in this issue Dario Zappa and colleagues at Brescia University in Italy simplify an already cheap and efficient synthesis method, demonstrating ZnO nanowire fabrication directly onto silicon substrates [1]. Meanwhile Nicolae Barson and colleagues in Germany point out the advantages of flame spray pyrolysis fabrication in a topical review [2] and, maximizing on existing resources, researchers in Denmark and Taiwan report cantilever sensing using a US20 commercial DVD-ROM optical pickup unit as the readout source [3]. The sensor is designed to detect physiological concentrations of soluble urokinase plasminogen activator receptor, a protein associated with inflammation due to HIV, cancer and other infectious diseases. With their extreme properties carbon nanostructures feature prominently in the issue, including the demonstration of a versatile and flexible carbon nanotube strain sensor [4] and a graphene charge sensor with sensitivities of the order of 1.3 × 10-3 e Hz-1/2 [5]. The issue of patterning for sensing devices is also tackled by researchers in the US who demonstrate a novel approach for multicomponent pattering metal/metal oxide nanoparticles on graphene [6]. Changes in electrical properties are an important indicator for sensing. In search of a better understanding of these systems Zhang et al from Southern Illinois University inspect the role of Joule heating, exothermal reactions and heat dissipation in gas sensing using nanowires [7]. The mechanisms behind electrical chemical sensors are also further scrutinized in a kinetics study by Joan Ramon Morante from the University of Barcelona in Spain. 'In spite of the growing commercial success many basic issues remain still open and under discussion limiting the broad use of this technology,' he explains. He discusses surface chemical reaction kinetics and the experimental results for different representative gas molecules to gain an insight into the chemical to electrical transduction mechanisms taking place [8]. Perhaps one of the most persistent targets in sensing research is increasing the sensitivity. Gauging environmental health issues around the commercial use of nanomaterials places high demands on low-level detection and spurred a collaboration of researchers in the UK, Croatia and Canada to look into the use of particle-impact voltammetry for detecting nanoparticles in environmental media [9]. At the University of Illinois Urbana-Champaign in the US, researchers have applied wave transform analysis techniques to the oscillations of an atomic force microscopy cantilever and tailored a time-frequency-domain filter to identify the region of highest vibrational energy [10]. The approach allows them to improve the signal to noise ratio by a factor 32 on current high-performance devices. In addition, researchers in Korea report how doping NiO nanofibres can improve the sensitivity to a number of gases, including ethanol, where the response was enhanced by as much as a factor of 217.86 [11]. Biomedicine is one of the largest industries for the application of nanotechnology in sensing. Demonstrating the state of the art, researchers in China use silicon wafers decorated with gold nanoparticles for label-free detection of DNA at concentrations as low as 1-10 fM, a sensitivity comparable t

Demming, Anna; Hierold, Christofer

2013-11-01

203

Magnetic multilayer interface anisotropy  

SciTech Connect

Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependant FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers if contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the transition temperature. During the next project the P.I. proposes to (1) extend the variable frequency FMR measurements to low temperature, where extremely large interface anisotropies are known to obtain in Ni/Mo and Ni/V and are proposed to exist in Ni/W; (2) obtain accurate dc anisotropies via a novel, variable temperature torque magnetometer currently under construction; (3) expand upon his initial findings in Fe/Cu multilayer investigations; (4) begin anisotropy investigations on Co/Ag and CoCr/Ag multilayers where the easy magnetization direction depends upon the Cr concentration; (4) make and characterize Bi based superconductors according to resistivity, thermal conductivity and thermoelectric power and construct YBaCuO based superconducting loop-gap'' resonators for use in his magnetic resonance work. 2 figs.

Pechan, M.J.

1991-01-01

204

Preparation of a PVdF-HFP/polyethylene composite gel electrolyte with shutdown function for lithium-ion secondary battery  

NASA Astrophysics Data System (ADS)

In order to improve the safety of lithium-ion secondary battery, a PVdF-HFP/polyethylene (PE) composite gel electrolyte with thermal shutdown function was prepared as an internal safety device. The composite gel electrolyte consists of a PVdF-HFP polymer, PE thermoplastic resin, and 1.0 mol/dm 3 LiClO 4/PC+EC (or LiPF 6/GBL+EC) plasticizer. When the PE content is over 23 wt.%, the electrical impedance of the composite gel electrolyte can increase rapidly by several orders, around the melting point of PE (mp: 90 or 104-115°C). By the SEM observation it was found that the PE particles uniformly dispersed in the PVdF-HFP gel electrolyte could be fused and formed into a continuous film at or near the PE melting point. The continuous PE film exhibits an ability to cut off the ion diffusion between cathode and anode, thus preventing the cell from thermal runaway. Also, a three-layered film of pure PVdF-HFP gel/composite gel/pure PVdF-HFP with a higher ionic conductivity and good mechanical strength was prepared for assembling a coin-type lithium-ion cell.

Liu, Xingjiang; Kusawake, Hiroaki; Kuwajima, Saburo

205

Thermal shutdown behavior of PVdF-HFP based polymer electrolytes comprising heat sensitive cross-linkable oligomers  

NASA Astrophysics Data System (ADS)

PVdF-HFP (polyvinylidenefluoride-hexafluoropropylene) polymer electrolytes comprising cross-linkable PEGDMA (polyethylene glycol dimethacrylate) oligomers with thermal shutdown characteristic have been developed. In contrast to the melting mechanism of polyolefin, this new polymer electrolyte possesses a thermal shutdown characteristic by a rapid cross-linking reaction of PEGDMA. The cross-linked PEGDMA network inside the PVdF-HFP matrix can provide the mechanical strength for the electrolytes, while the un-cross-linked PEGDMA oligomers serve as plasticizers for PVdF-HFP to improve the mobility of lithium ions at normal operation temperatures. In addition, the un-cross-linked PEGDMA oligomers can initiate cross-linking upon a sudden rise of temperature and thus provide thermal shutdown protection at elevated temperatures.

Cheng, C. L.; Wan, C. C.; Wang, Y. Y.; Wu, M. S.

206

Construction of redox-active multilayer film for electrochemically controlled release.  

PubMed

An electrochemically controlled drug release from a redox-active multilayer film is reported. The multilayer film is fabricated by alternate assembly of the electrochemical redox-active micelles and DNA. The buildup of multilayer films is monitored by spectroscopic ellipsometry, UV-vis spectroscopy, and fluorescence spectroscopy. A ferrocene-modified poly (ethyleneimine) (PEI-Fc) is used to form a hydrophobic ferrocene core and hydrophilic PEI shell micelle, showing the electrochemical redox-active properties. Hydrophobic pyrene (Py) molecules are then incorporated into the micelles. The PEI-Fc@Py micelles are assembled into the (PEI-Fc@Py/DNA) multilayer film by layer-by-layer assembly. Thanks to ferrocene groups with the properties of the hydrophilic-to-hydrophobic switch based on the electrical potential trigger, pyrene molecules can be control released from the multilayer film. The electrochemically controlled release of pyrene is investigated and confirmed by electrochemical quartz crystal microbalance and electrochemistry workstation. The (PEI-Fc@drug/DNA) multilayer film may have potential applications in the field of biomedical and nanoscale devices. PMID:23906288

Sun, Yi-xin; Ren, Ke-feng; Zhao, Yi-xiu; Liu, Xiang-sheng; Chang, Guo-xun; Ji, Jian

2013-09-01

207

Bactericidal and biocompatible properties of TiN/Ag multilayered films by ion beam assisted deposition.  

PubMed

Nanoscale TiN/Ag multilayered films of thickness 500 nm were synthesized on AISI317 stainless steel by ion beam assisted deposition (IBAD) with the modulation period of 4, 5, 6, 7.5, and 12 nm. The bactericidal and biocompatible properties of TiN/Ag multilayered films were investigated through Gram negative E. coli bacteria and L929 cells (mice fibroblast) as well as human umbilical vein endothelial cells (HUVEC). The results show that the TiN/Ag multilayered films with the modulation period of 7.5 nm possess the strongest bactericidal property. The cytotoxicity grade of TiN/Ag multilayered coating with the modulation periods of 7.5 nm, 12 nm is in 0-1 scope, which indicates this film has no cytotoxicity to L929. HUVEC on TiN/Ag multilayered film grows well and shows good cellularity. Auger electronic spectroscopy reveals the relationship between the structure of TiN/Ag multilayered film and the biomedical properties. PMID:18553178

Zhao, J; Cai, X M; Tang, H Q; Liu, T; Gu, H Q; Cui, R Z

2009-12-01

208

Multilayer ceramic actuator commercialization  

NASA Astrophysics Data System (ADS)

AVX is the largest US manufacturer of multilayer ceramic capacitors, producing 10's of millions per day. Multilayer ceramic actuators are manufactured using virtually identical fabrication methods. Fabrication from this ceramic tape allows tremendous latitude in device shape, size and material choice. This paper will discuss several different actuator configurations-including stacks, plates and chips- with respect to performance and cost tradeoffs. Virtually all developing smart material applications are 'technology driven,' however the widespread availability of devices at commercial scale relies on 'market pull' to achieve a balance of high annualized volumes and low cost. Given sufficient demand, devices can be produced such that the raw materials themselves dominate the unit cost. Generalized price-volume-performance relationships for the different actuator configurations can both guide system designers and focus long-term component development efforts.

Ritter, Andrew P.

1995-05-01

209

Surface parameters modification by multilayer coatings deposition for biomedical applications  

NASA Astrophysics Data System (ADS)

Studies are presented of the surface parameters of various multilayer coatings, namely, TiN, CrN, (Ti, Cr)N, TiN/TiC10N90, TiN/TiC20N80 deposited by means of Arc-PVD on stainless steel (1H18N9), as well as of the same coatings with an additional Al2O3 film deposited by reactive magnetron sputtering (RMS). The surface thickness, roughness and topography are estimated. Other parameters, such as the surface free energy (SFE) and fractional polarity are determined by means of the Wu and the Owens-Wendt-Rabel-Kaelble methods. Experiments are carried out on the in vitro cell/material interaction (in a fibroblasts culture) in order to determine the materials biomedical response. The results show some correlation between the surface properties and cell adhesion. The best biological response parameters (cell number, proliferation function, morphology) are obtained in the case of coatings with the highest values of the polar part component of the SFE and the fractional polarity, such as TiN, TiN/TiC10N90 and oxide coatings.

Zykova, A.; Safonov, V.; Virva, O.; Luk'yanchenko, V.; Walkowich, J.; Rogowska, R.; Yakovin, S.

2008-05-01

210

Multilayered Unipoled Piezoelectric Transformers  

Microsoft Academic Search

This study describes a multi-layer piezoelectric voltage and power transformer which has one direction poling, operates in a wide-frequency range and delivers both step-up and step-down voltages by inverting the electrical connections. In this design, the input and output electrodes are on the same side of the disk and are isolated from each other by a fixed gap. Investigations were

Shashank Priya; Seyit Ural; Hyeoung Woo Kim; Kenji Uchino; Toru Ezaki

2004-01-01

211

Multilayer Thermionic Refrigeration  

SciTech Connect

A new method of refrigeration is proposed. Efficient cooling is obtained by thermionic emission of electrons over Schottky barriers between metals and semiconductors. Since the barriers have to be thin, each barrier can have only a small temperature difference ({approximately}1 K) . Macroscopic cooling is obtained with a multilayer device. The same device is also an efficient generator of electrical power. A complete analytic theory is provided. {copyright} {ital 1998} {ital The American Physical Society}

Mahan, G.D.; Woods, L.M. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States)] [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States); [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6030 (United States)

1998-05-01

212

Memory effects in nanoscale systems  

NASA Astrophysics Data System (ADS)

Memory emerges quite naturally in systems of nanoscale dimensions: the change of state of electrons and ions is not instantaneous if probed at specific time scales, and it generally depends on the past dynamics. This means that the resistive, capacitive and/or inductive properties of these systems generally show interesting time-dependent (memory) features when subject to time-dependent perturbations. In other words, nanoscale systems behave as a combination of (or simply as) memristors, memcapacitors or meminductors, namely circuit elements whose resistance, capacitance and inductance, respectively, depend on the past states through which the system has evolved. After an introduction to the theory and properties of memristors, memcapacitors and meminductors, I will discuss several memory phenomena in nanostructures associated to charge, ion and spin dynamics and their far-reaching applications ranging from information storage to computation to biologically-inspired systems. Work supported in part by NSF, NIH, and DOE.

di Ventra, Massimiliano

2011-03-01

213

Surface and interface analysis of PVD AlON and ?-Al2O3 diffusion barriers  

Microsoft Academic Search

The suitability of PVD films of ?-Al2O3 and of ternary Al-O-N as diffusion barriers between a nickel based superalloy CMSX-4 and NiCoCrAlY for a possible application\\u000a in gas turbines was investigated. Therefore, an Al2O3 film and, alternatively, an Al-O-N film were deposited on CMSX-4 at 100?°C substrate temperature by means of reactive magnetron\\u000a sputtering ion plating (MSIP). After characterization of

R. Cremer; M. Witthaut; K. Reichert; D. Neuschütz

1999-01-01

214

Structural characterisation of oxygen diffusion hardened alpha-tantalum PVD-coatings on titanium.  

PubMed

Titanium substrates were coated with tantalum layers of 5?m thickness using physical vapour deposition (PVD). The tantalum layers showed a (110)-preferred orientation. The coated samples were hardened by oxygen diffusion. Using X-ray diffraction the crystallographic structure of the tantalum coatings was characterised, comparing untreated and diffusion hardened specimen conditions. Oxygen depth profiles were determined by glow discharge spectrometry. The hardening effect of the heat treatment was examined by Vickers microhardness testing. The increase of surface hardness caused by oxygen diffusion was at least 50%. PMID:24907733

Hertl, C; Koll, L; Schmitz, T; Werner, E; Gbureck, U

2014-08-01

215

N-Butyl- N-methylmorpholinium bis(trifluoromethanesulfonyl)imide–PVdF(HFP) gel electrolytes  

Microsoft Academic Search

Ionic liquid–polymer gels were prepared by incorporating N-butyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide (Mor1,4TFSI) and poly(vinylidene fluoride)–hexafluoropropylene copolymer (PVdF(HFP)) using three different methods in order to observe the variation of ionic conductivities according to the presence of propylene carbonate (PC) and various weight ratios between Mor1,4TFSI and gel polymer electrolyte (GPE). Ionic conductivities for each gel polymer electrolyte were measured with increasing temperature. Ionic

Ki-Sub Kim; Seung-Yeob Park; Sun-Hwa Yeon; Huen Lee

2005-01-01

216

Properties of Al doped zinc oxide films prepared by electron beam-PVD  

Microsoft Academic Search

Al doped ZnO (AZO) films were prepared on quartz substrates by the co-evaporation of ZnO and Al2O3 ingots by EB-PVD. EB power applied to the Al2O3 source was ranged from 3kW to 10kW, while EB power to the ZnO source was fixed at 3kW, at a substrate temperature of 400°C. X-ray diffraction measurement showed that the AZO films were weakly

N. Yamaguchi; T. Kuroyama; Y. Okuhara; H. Matsubara

2011-01-01

217

Hydrothermal corrosion of TiAlN and CrN PVD films on stainless steel  

Microsoft Academic Search

Hydrothermal corrosion of thin TiAlN and CrN PVD films (of 3?m thickness) in 100MPa water over a temperature range of 20–950°C is compared to the behavior of TiN films over the same T–P conditions. Corrosion resistance increases in the sequence TiN?TiAlN?CrN. A FeTiO3 (ilmenite) layer on the surface of the TiAlN film is almost chromium-free and provides protective properties up

Sergiy Korablov; M. A. M. Ibrahim; Masahiro Yoshimura

2005-01-01

218

Physicochemical studies of PVdF–HFP-based polymer–ionic liquid composite electrolytes  

Microsoft Academic Search

Polymer–ionic liquid composite electrolytes based on poly (vinylidenefluoride-co-hexafluoropropylene) (PVdF–HFP) and room\\u000a temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium hexafluorophosphate (DMOImPF6) have been synthesized and studied. The addition of dimethylacetamide (DMA) and propylene carbonate (PC), both with high\\u000a dielectric constant and low viscosity, to polymer electrolytes has been found to result in an enhancement of conductivity\\u000a by one order of magnitude. Composite polymer electrolytes

Boor Singh Lalia; K. Yamada; M. S. Hundal; Jin-Soo Park; Gu-Gon Park; Won-Yong Lee; Chang-Soo Kim; S. S. Sekhon

2009-01-01

219

Phonon Sidebands in Nanoscale Systems  

NASA Astrophysics Data System (ADS)

We calculate phonon sidebands for nanoscale systems in the Coulomb-Blockade regime where one electron at a time tunnels onto and off of the system. Using a combination of quantum chemistry and simple analytic calculations, we determine the relative strengths and the importance of environmental effects on the sidebands. Systems we have studied include the C72 (linked buckyballs), short nanotubes, and polyacetylene. In addition, we study molecule size effects on the appearance of phonon sidebands.

Chang, Connie; Sethna, James

2005-03-01

220

Nanoscale poling of polymer films.  

PubMed

Spots of second harmonic generation (SHG) are produced from nanopatterned sub-micrometer areas of nonlinear polymer media. Information is written by using a biased-AFM tip, a highly nonlinear polymer (poly(methyl metha-acrylate)-co-Disperse Red 1), and a novel "floating-tip nanolithography" (FTN) technique. Dipoles are oriented and aligned at the nanoscale under the biased-AFM tip, resulting in SHG production. The information is storable over weeks. PMID:23427063

Castagna, Riccardo; Milner, Alexander; Zyss, Joseph; Prior, Yehiam

2013-04-18

221

Synthesis of nanoscale antimony particles  

Microsoft Academic Search

For the search of new negative electrodes of Li-ion batteries, a low-temperature method has been developed for the preparation\\u000a of nanoscale antimony particles which uses an alkoxide-activated sodium hydride as reducing agent of antimony pentachloride.\\u000a X-ray diffraction and TEM studies confirm the obtaining of amorphous Sb nanoparticles dispersed in an organic matrix. 121Sb Mössbauer spectroscopy gives evidence for the occurrence

L. Balan; A. Dailly; R. Schneider; D. Billaud; P. Willmann; J. Olivier-Fourcade; J.-C. Jumas

222

Synthesis of nanoscale antimony particles  

Microsoft Academic Search

For the search of new negative electrodes of Li-ion batteries, a low-temperature method has been developed for the preparation\\u000a of nanoscale antimony particles which uses an alkoxide-activated sodium hydride as reducing agent of antimony pentachloride.\\u000a X-ray diffraction and TEM studies confirm the obtaining of amorphous Sb nanoparticles dispersed in an organic matrix. 121Sb Mssbauer spectroscopy gives evidence for the occurrence

L. Balan; A. Dailly; R. Schneider; D. Billaud; P. Willmann; J. Olivier-Fourcade; J.-C. Jumas

2005-01-01

223

PVdF-HFP\\/metal oxide nanocomposites: The matrices for high-conducting, low-leakage porous polymer electrolytes  

Microsoft Academic Search

Highly conducting porous polymer electrolytes comprised of poly(vinylidene-fluoride-co-hexafluoropropylene) (PVdF-HFP), metal oxide (TiO2, MgO, ZnO)\\/or mesoporous zeolite (MCM-41, SBA-15), ethylene carbonate (EC), propylene carbonate (PC), and LiClO4 were fabricated with a simple direct evaporation method. It was found that when metal oxide or mesoporous zeolite was mixed with PVdF-HFP, the impedance spectroscopy showed that the room temperature conductivity increased from 1.2×10?3Scm?1

Chun-Guey Wu; Ming-I. Lu; Chung-Chih Tsai; Huey-Jan Chuang

2006-01-01

224

Preparation of a PVdF-HFP\\/polyethylene composite gel electrolyte with shutdown function for lithium-ion secondary battery  

Microsoft Academic Search

In order to improve the safety of lithium-ion secondary battery, a PVdF-HFP\\/polyethylene (PE) composite gel electrolyte with thermal shutdown function was prepared as an internal safety device. The composite gel electrolyte consists of a PVdF-HFP polymer, PE thermoplastic resin, and 1.0mol\\/dm3 LiClO4\\/PC+EC (or LiPF6\\/GBL+EC) plasticizer. When the PE content is over 23wt.%, the electrical impedance of the composite gel electrolyte

Xingjiang Liu; Hiroaki Kusawake; Saburo Kuwajima

2001-01-01

225

Nanoscale laser processing and diagnostics  

NASA Astrophysics Data System (ADS)

The article summarizes research activities of the Laser Thermal Laboratory on pulsed nanosecond and femtosecond laser-based processing of materials and diagnostics at the nanoscale using optical-near-field processing. Both apertureless and apertured near-field probes can deliver highly confined irradiation at sufficiently high intensities to impart morphological and structural changes in materials at the nanometric level. Processing examples include nanoscale selective subtractive (ablation), additive (chemical vapor deposition), crystallization, and electric, magnetic activation. In the context of nanoscale diagnostics, optical-near-field-ablation-induced plasma emission was utilized for chemical species analysis by laser-induced breakdown spectroscopy. Furthermore, optical-near-field irradiation greatly improved sensitivity and reliability of electrical conductance atomic force microscopy enabling characterization of electron tunneling through the oxide shell on silicon nanowires. Efficient in-situ monitoring greatly benefits optical-near-field processing. Due to close proximity of the probe tip with respect to the sample under processing, frequent degradation of the probe end occurs leading to unstable processing conditions. Optical-fiber-based probes have been coupled to a dual-beam (scanning electron microscopy and focused ion beam) system in order to achieve in-situ monitoring and probe repair.

Hwang, David; Ryu, Sang-Gil; Misra, Nipun; Jeon, Hojeong; Grigoropoulos, Costas P.

2009-08-01

226

Nanoscale Science and Engineering Center  

NSDL National Science Digital Library

With support from the National Science Foundation, the Nanoscale Science and Engineering Center (NSEC) brings together researchers from Harvard University, the Massachusetts Institute of Technology, the University of California, Santa Barbara and the Museum of Science in Boston with participation by Delft University of Technology (Netherlands), the University of Basel (Switzerland), the University of Tokyo (Japan), and Brookhaven, Oak Ridge and Sandia National Laboratories "to construct novel electronic and magnetic devices with nanoscale sizes and understand their behavior, including quantum phenomena." The Center's main activities include research, education, and public outreach. The website lists the group's overlapping interdisciplinary research areas as Synthesis and Growth of Nanoscale Structures; Imaging Electrons inside Nanostructures; and Spins and Charges in Coherent Electronics. The links section provides information on NCES nanotechnology educational activities as well as other online resources and information on upcoming conferences in nanotechnology. The Highlights section provides just an overview of recently published research, but some of the websites for individual participants include articles and conference papers. The Annual Report also reviews recent activities and research from NSEC.

227

Three-dimensional, flexible nanoscale field-effect transistors as localized bioprobes.  

PubMed

Nanoelectronic devices offer substantial potential for interrogating biological systems, although nearly all work has focused on planar device designs. We have overcome this limitation through synthetic integration of a nanoscale field-effect transistor (nanoFET) device at the tip of an acute-angle kinked silicon nanowire, where nanoscale connections are made by the arms of the kinked nanostructure, and remote multilayer interconnects allow three-dimensional (3D) probe presentation. The acute-angle probe geometry was designed and synthesized by controlling cis versus trans crystal conformations between adjacent kinks, and the nanoFET was localized through modulation doping. 3D nanoFET probes exhibited conductance and sensitivity in aqueous solution, independent of large mechanical deflections, and demonstrated high pH sensitivity. Additionally, 3D nanoprobes modified with phospholipid bilayers can enter single cells to allow robust recording of intracellular potentials. PMID:20705858

Tian, Bozhi; Cohen-Karni, Tzahi; Qing, Quan; Duan, Xiaojie; Xie, Ping; Lieber, Charles M

2010-08-13

228

Junior Research Seminar: Nanoscale Patterning and Systems  

NSDL National Science Digital Library

Teri W. Odom, professor at Northwestern University, offers this course on Nanoscale Patterning and Systems. The research conducted through the course enables students to design and perform nanoscale patterning experiments with scanning probe lithography and bench-top fabrication techniques. The basic goals of the course are to help students understand current problems in nanoscale science and technology, perform bench-top nanoscale experiments, and use scanning probe techniques for patterning nanoscale features. To that end, this website offers a detailed syllabus explaining major concepts and breaking down the overall explanation of nanoscale patterning and systems, which students could use for better comprehension of nanotechnological concepts and instructors could use to help augment their own class materials.

Odom, Teri W.

2012-04-12

229

Investigation of Ti and Cr based PVD coatings deposited onto HSS Co 5 twist drills  

NASA Astrophysics Data System (ADS)

This study investigates the properties and cutting performance of thin TiN, TiAlN, CrAlN and KTRN coatings applied by two PVD techniques. PVD techniques ARC and SARC (it denotes the arc method by STATON company, Slovakia - deposited with smaller microdrops) were used for the deposition of thin coatings onto twist drills prepared by powder metallurgy. Conventional types of coatings - monolayers TiN, TiAlN, CrAlN and advanced type of the coating - monolayer KTRN (denoted by producer - STATON company Slovakia) on the basis of Ti and Al deposited with smaller drops on the surface - were analyzed by standard techniques for surface status and quality assessment - coating thickness, chemical composition by EDX analysis, adhesion, hardness, roughness and tribological properties at room temperature. Durability testing of the twist drills was carried out according to the standard ISO 3685-1999. CrAlN and TiAlN monolayers achieved lower roughness when compared to monolayer TiN and advanced type of the monolayer KTRN. TiAlN and KTRN coatings which leads to the achievement of higher hardness and better coating quality. The microhardness values were ˜35 GPa. The results showed two to four times lower flank wear VB of the evaluated drills with TiAlN and KTRN coatings in comparison with equivalent uncoated material of the drill. The deposited TiAlN and KTRN coatings contributed to the improvement of their durability.

Kottfer, D.; Ferdinandy, M.; Kaczmarek, L.; Ma?ková, I.; Be?o, J.

2013-10-01

230

X-ray nanoscale profiling of layer-by-layer assembled metal/organophosphonate films.  

PubMed

The nanoscale structure of multilayer metal/phosphonate thin films prepared via a layer-by-layer assembly process was studied using specular X-ray reflectivity (XRR), X-ray fluorescence (XRF), and long-period X-ray standing wave (XSW) analysis. After the SiO(2) X-ray mirror surfaces were functionalized with a monolayer film terminated with phosphonate groups, the organic multilayer films were assembled by alternating immersions in (a) aqueous solutions containing Zr(4+), Hf(4+), or Y(3+) cations and then (b) organic solvent solutions of PO(3)-R-PO(3), where R was a porphyrin or porphyrin-square spacer molecule. The different heavy metal cations provided X-ray fluorescence marker layers at different heights within the different multilayer assemblies. The XSW measurements used a 22 nm period Si/Mo multilayer mirror. The long-period XSW generated by the zeroth-order (total external reflection) through fourth-order Bragg diffraction conditions made it possible to examine the Fourier transforms of the fluorescent atom distributions over a much larger q(z)() range in reciprocal space than previously achieved. PMID:15350067

Libera, Joseph A; Gurney, Richard W; Nguyen, SonBinh T; Hupp, Joseph T; Liu, Chian; Conley, Ray; Bedzyk, Michael J

2004-09-14

231

The effects of length scale on the deformation behavior of metallic multilayers-Part II : modeling /.  

SciTech Connect

The experimental observations described in a companion presentation of the same title by Misra et al. highlight that unique, non-bulk rolling textures are achieved in nanoscale multilayered thin films. Specifically, Cu/Nb multilayers deposited with an initial Kudjumov-Sachs orientation relation between Cu and Nb grains and with an initial individual layer thickness of 75nm preserve that relation during rolling. In contrast, samples with micron-scale individual layer thickness do not. To help understand this layer-dependent response, a crystal plasticity model is presented in which the Cu and Nb phases respond by slip on {l_brace}111{r_brace}/<110> systems in the fcc Cu case, and {l_brace}110{r_brace} / <111 > systems in the bcc Nb phase. Grains within each layered phase are required to plastically deform by a reduction in thickness and corresponding elongation in the rolling direction, with zero plastic strain along the transverse axis. The model also adopts the observation for nano-scale multilayers that the Kudjumov-Sachs orientation relation is preserved; in particular, the e 1 11> Cu and e1 10> Nb directions remain parallel to the interface normal during rolling. The crystal plasticity model then furnishes the minimum plastic work to deform a grain, as a function of grain orientation. For Cu grains, the plastic work is invariant of grain orientation, provided the critical resolved shear stress is uniform on all fcc slip systems. However, the corresponding plastic work in Nb grains is very dependent on grain orientation and has a strong minimum. This large anisotropy serves as a driving force for Nb grains to rotate around their <110> interface normal, toward the minimum. The resulting prediction for rolling texture in Nb layers agrees well with experimental observations in nanoscale Cu/Nb multilayers.

Misra, A. (Amit); Hirth, John Price,; Anderson, P. M. (Peter M.)

2002-01-01

232

Rule-based software tool to specify the manufacturing process parameters for a contoured EB-PVD coating  

Microsoft Academic Search

A rule-based design software tool has been developed to specify the manufacturing process parameters to fabricate a contoured electron beam physical vapor deposited (EB-PVD) partially stabilized zirconia (PSZ) thermal barrier coating (TBC) on a curved surface. The expert data for this tool was developed from model predictions based on an experimentally verified, theoretical model of coating deposition rates as a

William C. Weir; Richard D. Sisson; Sudhangshu Bose

2000-01-01

233

Novel porous separator based on PVdF and PE non-woven matrix for rechargeable lithium batteries  

NASA Astrophysics Data System (ADS)

The novel porous separator based on PVdF (poly(vinylidene fluoride)) and a PE (polyethylene) non-woven matrix is prepared by coating PVdF/NMP solution on the matrix (NMP: N-methyl-2-pyrrolidone). The pore structure is generated in the PVdF region by phase inversion of the polymer solution. The PE non-woven matrix imparts mechanical strength and a thermal shut-down property to the separator, while the PVdF component provides a hydrophilic ionic conducting phase. The physical properties of the separator, such as morphology, pore size and its distribution, porosity and mechanical strength, are measured. The ionic conductivity of the separator is 8.9 × 10 -4 S cm -1 at 25 °C. The capacity at the C/2 rate is maintained at about 86% of the initial value on the 100th cycle at the room temperature. The electrolyte is stable up to 4.5 V in the presence of the novel separator.

Lee, Yong Min; Kim, Jun-Woo; Choi, Nam-Soon; Lee, Je An; Seol, Wan-Ho; Park, Jung-Ki

234

Lithium Ion Transport Across and Between Phase Boundaries in Heterogeneous Polymer Electrolytes, Based on PVdF.  

National Technical Information Service (NTIS)

Initial investigations of polymer electrolytes based on PVdF-HFP and LiPF6 dissolved in either EC/PC or EC/DMC mixtures have been carried out via high pressure complex impedance methods and 7Li NMR. All results indicate that the polymer matrix, while effe...

S. G. Greenbaum

1998-01-01

235

Mechanical strength improvement of electrical discharge machined cemented carbides through PVD (TiN, TiAlN) coatings  

Microsoft Academic Search

Electrical discharge machining (EDM) is an alternative shaping route for manufacturing complex component shapes of hard and brittle materials as WC–Co cemented carbides (hardmetals). However, it results in a heat-affected surface layer with poor surface integrity that often leads to mechanical degradation of these materials. This work focuses on assessing the feasibility of physical vapor deposition (PVD) of hard coatings

B. Casas; A. Lousa; J. Calderón; M. Anglada; J. Esteve; L. Llanes

2004-01-01

236

Microstructure and phase stability of EB-PVD alumina and alumina\\/zirconia for thermal barrier coating applications  

Microsoft Academic Search

This paper describes recent progress on research aimed at improving the performance of EB-PVD thermal barrier coatings (TBCs) for gas turbine applications by incorporating alumina as an oxygen diffusion barrier between the bond coat and zirconia. Two approaches are being investigated, either a single, discrete alumina layer, or a graded alumina\\/zirconia layer. This paper reports on preliminary experiments in which

U. Leushake; T. Krell; U. Schulz; M. Peters; W. A. Kaysser; B. H. Rabin

1997-01-01

237

Characterization of PVdF(HFP) gel electrolytes based on 1-(2-Hydroxyethyl)-3-methyl imidazolium ionic liquids.  

PubMed

Poly(vinylidenefluoride)-hexafluoropropylene (PVdF(HFP))-ionic liquid gel electrolytes were prepared using ionic liquids based on 1-(2-hydroxyethyl)-3-methyl imidazolium tetrafluoroborate and 1-(2-hydroxyethyl)-3-methyl imidazolium hexafluorophosphate. A conventional metathesis reaction was used to prepare these ionic liquids, which have high purity and exhibit a liquid state at room temperature. The prepared polymer-ionic liquid gel proved to be a free-standing and rubbery film in which the degree of transparency differed according to the ratio and type of ionic liquid used. TGA and FTIR analyses confirmed that the solvent, N,N-Dimethylacetamide (DMAC), used for mixing PVdF(HFP) polymer with ionic liquid was almost totally removed during the gelling and drying processes. SEM photographs were taken of the surface structure of the PVdF(HFP)-ionic liquid gel in order to evaluate the morphology of the film's surface according to the mixing ratio and the nature of the ionic liquid. The thermal behaviors of PVdF(HFP)-ionic liquid gels were observed to be similar to those of neat ionic liquids through DSC analysis, and the compatibility between the polymer and ionic liquid was investigated by XRD analysis. The ionic conductivities of all the gels were 10(-3)-10(-5) S cm(-1) in a temperature range of 20-70 degrees C. PMID:16853301

Yeon, Sun-Hwa; Kim, Ki-Sub; Choi, Sukjeong; Cha, Jong-Ho; Lee, Huen

2005-09-29

238

Synthesis of nanoscale antimony particles  

NASA Astrophysics Data System (ADS)

For the search of new negative electrodes of Li-ion batteries, a low-temperature method has been developed for the preparation of nanoscale antimony particles which uses an alkoxide-activated sodium hydride as reducing agent of antimony pentachloride. X-ray diffraction and TEM studies confirm the obtaining of amorphous Sb nanoparticles dispersed in an organic matrix. 121Sb Mössbauer spectroscopy gives evidence for the occurrence of interactions between antimony and the matrix. These interactions are modified by the washing treatments.

Balan, L.; Dailly, A.; Schneider, R.; Billaud, D.; Willmann, P.; Olivier-Fourcade, J.; Jumas, J.-C.

2005-09-01

239

Magnetic metallic multilayers  

NASA Astrophysics Data System (ADS)

Utilizing self-consistent Hartree-Fock calculations, several aspects of multilayers and interfaces are explored: enhancement and reduction of the local magnetic moments, magnetic coupling at the interfaces, magnetic arrangements within each film and among non-neighboring films, global symmetry of the systems, frustration, orientation of the various moments with respect to an outside applied field, and magnetic-field induced transitions. Magnetoresistance of ferromagnetic-normal-metal multilayers is found by solving the Boltzmann equation. Results explain the giant negative magnetoresistance encountered in these systems when an initial antiparallel arrangement is changed into a parallel configuration by an external magnetic field. The calculation depends on (1) geometric parameters (thicknesses of layers), (2) intrinsic metal parameters (number of conduction electrons, magnetization, and effective masses in layers), (3) bulk sample properties (conductivity relaxation times), (4) interface scattering properties (diffuse scattering versus potential scattering at the interfaces), and (5) outer surface scattering properties (specular versus diffuse surface scattering). It is found that a large negative magnetoresistance requires considerable asymmetry in interface scattering for the two spin orientations. Features of the interfaces that may produce an asymmetrical spin-dependent scattering are studied: varying interfacial geometric random roughness with no lateral coherence, correlated (quasi-periodic) roughness, and varying chemical composition of the interfaces. The interplay between these aspects of the interfaces may enhance or suppress the magnetoresistance, depending on whether it increases or decreases the asymmetry in the spin-dependent scattering of the conduction electrons.

Hood, R. Q.

1994-04-01

240

Influence of the structure of the composite: ‘nitrided layer\\/PVD coating’ on the durability of forging dies made of steel DIN1.2367  

Microsoft Academic Search

The paper presents research results of the influence of the ‘nitrided layer\\/PVD coating’ composite structure on the durability of forging dies made of steel DIN-1.2367. Five structures of the composite with different PVD coating materials were investigated. The following types of PVD coatings were applied: TiN\\/Ti(C,N)gradient, (Ti,Cr)N, (CrN\\/TiN)×3, (Cr\\/CrN)×3, CrN. The investigated composites were created by means of the surface

Jerzy Smolik; Michael Gulde; Jan Walkowicz; Jan Suchanek

2004-01-01

241

Spreading and dewetting in nanoscale lubrication  

Microsoft Academic Search

This article critically reviews the fundamental scientific tools, as well as constructs cohesive schemes for potential applications, relevant to the molecularly-thin liquid film technology. Our focus is to understand the nanoscale dynamic behavior of thin lubricant films, relevant to the emerging field of nanotechnology, especially for achieving durability and reliability in the nanoscale devices. Our goal is to present a

T. E. Karis; W. T. Kim; M. S. Jhon

2005-01-01

242

Thermal simulation techniques for nanoscale transistors  

Microsoft Academic Search

Thermal simulations are important for advanced electronic sys- tems at multiple length scales. A major challenge involves electro- thermal phenomena within nanoscale transistors, which exhibit nearly ballistic transport both for electrons and phonons. The ther- mal device behavior can influence both the mobility and the leakage currents. We discuss recent advances in modeling coupled electron- phonon transport in future nanoscale

Jeremy A. Rowlette; Eric Pop; Sanjiv Sinha; Mathew Panzer; Kenneth E. Goodson

2005-01-01

243

Nanoscale molecular-switch crossbar circuits  

Microsoft Academic Search

Molecular electronics offer an alternative pathway to construct nanoscale circuits in which the critical dimension is naturally associated with molecular sizes. We describe the fabrication and testing of nanoscale molecular-electronic circuits that comprise a molecular monolayer of [2]rotaxanes sandwiched between metal nanowires to form an 8 × 8 crossbar within a 1 µm2 area. The resistance at each cross point

Yong Chen; Gun-Young Jung; Douglas A. A. Ohlberg; Xuema Li; Duncan R. Stewart; Jan O. Jeppesen; Kent A. Nielsen; J. Fraser Stoddart; R. Stanley Williams

2003-01-01

244

Nanoscale wires and related devices  

US Patent & Trademark Office Database

The present invention relates generally to sub-microelectronic circuitry, and more particularly to nanometer-scale articles, including nanoscale wires which can be selectively doped at various locations and at various levels. In some cases, the articles may be single crystals. The nanoscale wires can be doped, for example, differentially along their length, or radially, and either in terms of identity of dopant, concentration of dopant, or both. This may be used to provide both n-type and p-type conductivity in a single item, or in different items in close proximity to each other, such as in a crossbar array. The fabrication and growth of such articles is described, and the arrangement of such articles to fabricate electronic, optoelectronic, or spintronic devices and components. For example, semiconductor materials can be doped to form n-type and p-type semiconductor regions for making a variety of devices such as field effect transistors, bipolar transistors, complementary inverters, tunnel diodes, light emitting diodes, sensors, and the like.

2007-11-27

245

Nanoscale  

NSDL National Science Digital Library

Nanotechnology continues to be a field of inquiry that is growing quickly, and this new online peer reviewed journal is a most welcome addition. The journal is published monthly as a collaborative venture between RSC Publishing and the National Center for Nanoscience and Technology (NCNST) in Beijing, China. Some of the topics covered in the journal include nanoelectronics, molecular nanoscience, and nanomedicine. The first issues was released in September 2009, and visitors can read through pieces like "How safe are carbon nanotubes?" and "Mechanised nanoparticles for drug delivery". On the journal's site, visitors can browse through the archive, sign up for their RSS feed, and also read over the author guidelines. Finally they can also use some of their online "Tools" to send along a link to the journal to a friend or colleague.

246

Cyclic Oxidation Behaviors of Eb-Pvd dy Doped ?-NiAl Coatings at 1100°C  

NASA Astrophysics Data System (ADS)

?-NiAl as a promising oxidation resistant coating material due to it high melting point and good oxidation resistant, however it reveals poor cyclic oxidation performance. In this paper, reactive element Dy doped ?-NiAl coatings were prepared by electron beam physical vapor deposition (EB-PVD). Dy doping led to the grain refinement microstructure and Dy segregated mainly at grain boundaries. Cyclic oxidation behaviors of the coatings at 1100°C were investigated. The 0.05at.% Dy and 0.1at.% Dy doped coatings exhibited lower oxidation rate and better cyclic oxidation performance, as compared to the undoped coating. The effects of Dy addition on the morphologies and growth mechanism of the oxide scale were discussed.

Guo, Hongbo; Wang, Shixing; Wang, Xiaoyan; Gong, Shengkai

247

Optimization of hybrid PVD process of TiAlN coatings by Taguchi method  

NASA Astrophysics Data System (ADS)

Taguchi method was applied to optimize the performances of TiAlN coatings deposited by hollow cathode discharge ion plating (HCDIP) and medium frequency magnetron sputtering ion plating (MFMSIP) hybrid physical vapor deposition (PVD) coating system. TiAlN coatings prepared by this coating system showed columnar microstructure with the preferred orientation of (1 1 1). The sensitive parameters on microhardness were total deposition pressure and substrate bias voltage, and the sensitive parameter on milling performance was substrate bias voltage. The optimum conditions were total deposition pressure: 0.9 Pa, flowrate of N 2: 250 sccm, substrate bias voltage: -120 V. And the confirming experiment obtained the optimum TiAlN coating with microhardness of 25.8 GPa, and the best TiAlN-coated end mill performed the milling length of 50.8 m.

Yu, Donghai; Wang, Chengyong; Cheng, Xiaoling; Zhang, Fenglin

2008-12-01

248

Computational modelling of constrained sintering in EB-PVD thermal barrier coatings  

NASA Astrophysics Data System (ADS)

A micromechanical model is developed to simulate the evolution of microstructure during in-service sintering and eventual inter-columnar cracking in coatings made using electron beam vapour deposition (EB-PVD) route. The coating is idealized with a discrete distribution of axisymmetric asperities across interfaces between columnar grains. The model assumes that inter-columnar sintering is driven by changes in interface free energy of columns and the potential energy of the applied stress. Much faster diffusion that occurs over the free surfaces of the asperities is neglected. It is further assumed that the rate of sintering of the contacting asperities is determined by diffusion along the interface between the contacting asperities. Time evolution of contact modulus of the coating is accounted for as a function of sintering strain. The developed macroscopic constitutive model is employed to evaluate the sensitivity of the sintering response to imperfections and examine the conditions under which inter-columnar cracks can develop within the coating.

Kumar, S.; Cocks, A. C. F.

2013-09-01

249

Investigation of failure mechanism of thermal barrier coatings (TBCs) deposited by EB-PVD technique  

NASA Astrophysics Data System (ADS)

Failure mechanism of thermal barrier coatings (TBCs) prepared by electron beam physical vapor deposition (EB-PVD) technique owing to formation of micro cracks was investigated. The TBCs were deposited on the Ni-based super alloy IN-100 and the micro cracks were observed within the top ceramic coat of thermally cycled TBCs at 1050°C. It was observed that these cracks propagate in the ceramic coat in the direction normal to interface while no cracks were observed in the bond coat. SEM/EDS studies revealed that some non-uniform oxides were formed on the interface between ceramic top and metallic bond coat just below the cracks. Study proposed that the cracks were initiated due to stress owing to big difference in Pilling-Bed worth ratio of non-uniform oxides as well as thermal stress, which caused the formation of cracks in top ceramic coat leading to failure of TBCs

Shahid, M. R.; Abbas, Musharaf

2013-06-01

250

Multilayer optical dielectric coating  

DOEpatents

A highly damage resistant, multilayer, optical reflective coating includes alternating layers of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating for a predetermined wavelength. Broadband reflectors are made by using a number of narrowband reflectors, each covering a portion of the broadband.

Emmett, John L. (Pleasanton, CA)

1990-01-01

251

Diffusion bonding of CMSX-4 to UDIMET 720 using PVD-coated interfaces and HIP  

SciTech Connect

There is an increasing interest in development of manufacturing methods for Dual Property BLISKs (BLaded dISKs), consisting of creep resistant airfoils and fatigue resistant disks bonded together by a durable joint. Optimum heat treatments are, however, very different for creep resistant single crystal CMSX-4 and fatigue resistant polycrystalline Udimet 720 selected in this study, but fortunately the first aging treatment for CMSX-4 (1140 C, 2-6h, AC) is similar to the partial solution treatment of U 720 HS2 (1115 C, 4h, OQ). Based on this, diffusion bonding was performed by HIP at 1120 C and 200 MPa argon pressure for 4 h, followed by cooling to 400 C. Subsequently, a shortened Udimet 720 HS2 two-step aging treatment was adopted by heating to 650 C for 6 h followed by cooling to 400 C, heating to 760 C for 2 h, and finally cooling to R.T. under remaining HIP pressure. Plasma etching followed by thin (80 nm) PVD coating with either nickel or titanium were used to clean and protect the polished surfaces before joining. The selection of coatings was governed by the possibility to reduce oxidized nickel by flushing with hydrogen at 330 C during evacuation of the HIP capsules, and by the large solubility of oxygen in titanium. Hot tensile testing was performed at 750 C on both joined and reference materials subjected to the modified heat treatment. Initially solution treated Udimet 720 and CMSX-4 comprised the reference materials. The testing showed that joints with Ni-PV coatings were almost as strong as Udimet 720 (although with very limited elongation), while the joints with Ti-PVD coatings were weaker.

Larker, R. [Lulea Univ. of Technology (Sweden). Div. of Engineering Materials; Ockborn, J.; Selling, B. [Volvo Aero Corp., Trollhattan (Sweden)

1999-07-01

252

New Theory of Multilayered Plates.  

National Technical Information Service (NTIS)

The work presents a new approach to the dynamics of multilayered plates with anisotrophy and viscoelasticity. Some of the layers may be constituted by thinly laminated materials giving rise to stress-couples. The theory takes into account the fundamental ...

M. A. Biot

1970-01-01

253

Multilayer Superinsulation Development and Testing.  

National Technical Information Service (NTIS)

For the measurement of the thermal conductance of multilayer superinsulation blankets a flat, guarded-hot-plate calorimeter was developed and manufactured. The physical arrangement of the calorimeter, the range of operating temperature and the method of m...

E. Klippel H. Langer

1974-01-01

254

Charge transport in nanoscale junctions.  

PubMed

Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at the molecular level. Nanoscale charge transport experiments in ionic liquids extend the field to high temperatures and to systems with intriguing interfacial potential distributions. Other directions may include dye-sensitized solar cells, new sensor applications and diagnostic tools for the study of surface-bound single molecules. Another motivation for this special issue is thus to highlight activities across different research communities with nanoscale charge transport as a common denominator. This special issue gathers 27 articles by scientists from the United States, Germany, the UK, Denmark, Russia, France, Israel, Canada, Australia, Sweden, Switzerland, the Netherlands, Belgium and Singapore; it gives us a flavour of the current state-of-the-art of this diverse research area. While based on contributions from many renowned groups and institutions, it obviously cannot claim to represent all groups active in this very broad area. Moreover, a number of world-leading groups were unable to take part in this project within the allocated time limit. Nevertheless, we regard the current selection of papers to be representative enough for the reader to draw their own conclusions about the current status of the field. Each paper is original and has its own merit, as all papers in Journal of Physics: Condensed Matter special issues are subjected to the same scrutiny as regular contributions. The Guest Editors have deliberately not defined the specific subjects covered in this issue. These came out logically from the development of this area, for example: 'Traditional' solid state nanojunctions based on adsorbed layers, oxide films or nanowires sandwiched between two electrodes: effects of molecular structure (aromaticity, anchoring groups), symmetry, orientation, dynamics (noise patterns) and current-induced heating. Various 'physical effects': inelastic tunnelling and Coulomb blockade, polaron effects, switching modes, and negative differential resistance; the role of many particle excitations, new surface states in semiconductor electrodes, various mechanisms for

Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

2008-09-01

255

CdS Nanoscale Photodetectors.  

PubMed

CdS nanostructures have received much attention in recent years as building blocks for optoelectronic devices due to their unique physical and chemical properties. This progress report provides an overview of recent research about rational design of CdS nanoscale photodetectors. Three kinds of photodetectors according to the metal-semiconductor contact types are discussed in detail: Ohmic contact, Schottky contact, and field enhanced transistor configuration. The focus is on the tuning of optical and electrical properties CdS nanostructures by element doping, composition and bandgap engineering, and heterojunction integration, along with thus modified device performances generated during these tuning processes. Latest concepts of photodetector design such as flexible, self-powered, plasmonic, and piezophototronic photodetectors with novel properties are introduced to demonstrate the future directions of such an exciting research field. PMID:24634326

Deng, Kaimo; Li, Liang

2014-05-01

256

Ionic transport, thermal, XRD, and phase morphological studies on LiCF 3 SO 3 -based PVC–PVdF gel electrolytes  

Microsoft Academic Search

The plasticized polymer electrolyte composed of polyvinylchloride (PVC) and polyvinylidene fluoride (PVdF) as host polymer,\\u000a the mixture of ethylene carbonate and propylene carbonate as plasticizer, and LiCF3SO3 as a salt was studied. The effect of the PVC-to-PVdF blend ratio with the fixed plasticizer and salt content on the ionic\\u000a conduction was investigated. The electrolyte films reveal a phase-separated morphology due

P. Vickraman; V. Aravindan; M. Selvambikai; N. Shankarasubramanian

2009-01-01

257

Lithium ion conducting PVdF-HFP composite gel electrolytes based on N-methoxyethyl- N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide ionic liquid  

Microsoft Academic Search

Blends of PVdF-HFP and ionic liquids (ILs) are interesting for application as electrolytes in plastic Li batteries. They combine the advantages of the gel polymer electrolytes (GPEs) swollen by conventional organic liquid electrolytes with the nonflammability, and high thermal and electrochemical stability of ILs.In this work we prepared and characterized PVdF-HFP composite membranes swollen with a solution of LiTFSI in

S. Ferrari; E. Quartarone; P. Mustarelli; A. Magistris; M. Fagnoni; S. Protti; C. Gerbaldi; A. Spinella

2010-01-01

258

Multilayer thermal barrier coating systems  

DOEpatents

The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

Vance, Steven J. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Sloan, Kelly M. (Longwood, FL)

2000-01-01

259

New directions for nanoscale thermoelectric materials research  

NASA Technical Reports Server (NTRS)

Many of the recent advances in enhancing the thermoelectric figure of merit are linked to nanoscale phenomena with both bulk samples containing nanoscale constituents and nanoscale materials exhibiting enhanced thermoelectric performance in their own right. Prior theoretical and experimental proof of principle studies on isolated quantum well and quantum wire samples have now evolved into studies on bulk samples containing nanostructured constituents. In this review, nanostructural composites are shown to exhibit nanostructures and properties that show promise for thermoelectric applications. A review of some of the results obtained to date are presented.

Dresselhaus, M. S.; Chen, G.; Tang, M. Y.; Yang, R. G.; Lee, H.; Wang, D. Z.; Ren, F.; Fleurial, J. P.; Gogna, P.

2005-01-01

260

Artificial multilayers and nanomagnetic materials  

PubMed Central

The author has been actively engaged in research on nanomagnetic materials for about 50 years. Nanomagnetic materials are comprised of ferromagnetic systems for which the size and shape are controlled on a nanometer scale. Typical examples are ultrafine particles, ultrathin films, multilayered films and nano-patterned films. In this article, the following four areas of the author’s studies are described. (1) Mössbauer spectroscopic studies of nanomagnetic materials and interface magnetism. (2) Preparation and characterization of metallic multilayers with artificial superstructures. (3) Giant magnetoresistance (GMR) effect in magnetic multilayers. (4) Novel properties of nanostructured ferromagnetic thin films (dots and wires). A subject of particular interest in the author’s research was the artificially prepared multilayers consisting of metallic elements. The motivation to initiate the multilayer investigation is described and the physical properties observed in the artificial multilayers are introduced. The author’s research was initially in the field of pure physical science and gradually extended into applied science. His achievements are highly regarded not only from the fundamental point of view but also from the technological viewpoint.

SHINJO, Teruya

2013-01-01

261

Rule-based software tool to specify the manufacturing process parameters for a contoured EB-PVD coating  

NASA Astrophysics Data System (ADS)

A rule-based design software tool has been developed to specify the manufacturing process parameters to fabricate a contoured electron beam physical vapor deposited (EB-PVD) partially stabilized zirconia (PSZ) thermal barrier coating (TBC) on a curved surface. The expert data for this tool was developed from model predictions based on an experimentally verified, theoretical model of coating deposition rates as a function of position in the PVD vapor cloud (Knudsen cosine law). The predictive model was used for a wide variety of process parameters, including shadowing and non-uniform angular rotational velocity, to develop a database of contoured coating profiles (forward chaining). A coating profile matching routine was developed to identify the process parameters that yield a coating profile that matches the designers coating profile. The focus of this presentation will be on the software tool with emphasis on the expert database development and the coating thickness profile matching for a curved surface.

Weir, William C.; Sisson, Richard D.; Bose, Sudhangshu

2000-10-01

262

PVD Silicon Carbide as a Thin Film Packaging Technology for Antennas on LCP Substrates for Harsh Environments  

NASA Technical Reports Server (NTRS)

This paper describes an effort to develop a thin film packaging technology for microfabricated planar antennas on polymeric substrates based on silicon carbide (SiC) films deposited by physical vapor deposition (PVD). The antennas are coplanar waveguide fed dual frequency folded slot antennas fabricated on liquid crystal polymer (LCP) substrates. The PVD SiC thin films were deposited directly onto the antennas by RF sputtering at room temperature at a chamber pressure of 30 mTorr and a power level of 300 W. The SiC film thickness is 450 nm. The return loss and radiation patterns were measured before and after the SiC-coated antennas were submerged into perchloric acid for 1 hour. No degradation in RF performance or physical integrity of the antenna was observed.

Scardelletti, Maximilian C.; Stanton, John W.; Ponchak, George E.; Jordan, Jennifer L.; Zorman, Christian A.

2010-01-01

263

Design of radiation resistant metallic multilayers for advanced nuclear systems  

NASA Astrophysics Data System (ADS)

Helium implantation from transmutation reactions is a major cause of embrittlement and dimensional instability of structural components in nuclear energy systems. Development of novel materials with improved radiation resistance, which is of the utmost importance for progress in nuclear energy, requires guidelines to arrive at favorable parameters more efficiently. Here, we present a methodology that can be used for the design of radiation tolerant materials. We used synchrotron X-ray reflectivity to nondestructively study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers. The results, supported by transmission electron microscopy, show a direct correlation between reduced swelling in nanoscale multilayers and increased interface area per unit volume, consistent with helium storage in Cu/Nb interfaces in forms that minimize dimensional changes. In addition, for Cu/Nb layers, a linear relationship is demonstrated between the measured depth-dependent swelling and implanted He density from simulations, making the reflectivity technique a powerful tool for heuristic material design.

Zhernenkov, Mikhail; Gill, Simerjeet; Stanic, Vesna; DiMasi, Elaine; Kisslinger, Kim; Baldwin, J. Kevin; Misra, Amit; Demkowicz, M. J.; Ecker, Lynne

2014-06-01

264

Metal-oxide interfaces at the nanoscale  

NASA Astrophysics Data System (ADS)

In contrast to the 6×7 spacing registry that yields a minimum coincidence misfit, we find that the nanoscale Cu2O-Cu interface formed during initial oxidation of Cu(111) surfaces adopts a 5×6 coincidence site lattice that is accommodated by an increased lattice misfit strain. A simple analysis on the equilibrium elastic strain in epitaxial oxide nanoislands reveals a previously unnoticed correlation between the interface structure and surface stresses at the nanoscale.

Zhou, Guangwen

2009-06-01

265

Science and Technology at the Nanoscale  

NSDL National Science Digital Library

Northwestern University offers this graduate course on nanoscience to introduce students to the field. Taught by Professor Teri Odom, this course presents students with contemporary issues in nanoscience and nanotechnology as well as provide training on advanced nanoscale instrumentation. The website includes PDF lecture slideshows that provide more detailed information on subjects such as scanning probe microscopy, nanofabrication, and nanoscale electronics and photonics. This would be a good resource for teachers who want to incorporate nanoscience into their pre-existing chemistry classes.

Odom, Teri W.

2012-04-12

266

Nanoscale phase transitions within single ion tracks  

Microsoft Academic Search

The dynamics of track development due to the passage of energetic ions through solids is a long-standing issue relevant to nuclear materials, age-dating of minerals, space exploration, and nanoscale fabrication of novel devices. We have integrated computer simulation and experimental approaches to investigate nanoscale phase transitions under the extreme conditions created within single tracks of energetic ions in the Gd2Zr2-xTixO7

William Weber; Ram Devanathan; Pedro Moreira

2011-01-01

267

Nanoscale effects of antibiotics on P. aeruginosa  

Microsoft Academic Search

Studying living bacteria at the nanoscale, in their native liquid environment opens an unexplored landscape. We focus on Pseudomonas aeruginosa and demonstrate how the cell wall is biophysically affected at the nanoscale by two reference antibiotics (ticarcillin, tobramycin). The elasticity of the cells drops dramatically after treatment (from 263+\\/-70 kPa to 50+\\/-18 and 24+\\/-4 kPa respectively on ticarcillin and tobramycin

Cecile Formosa; Marion Grare; Raphaël E. Duval; Etienne Dague

268

Micro-abrasion wear testing of PVD TiN coatings on untreated and plasma nitrided AISI H13 steel  

Microsoft Academic Search

An abrasive wear test, based on the ball-crater technique, has been used to evaluate the wear resistance of PVD TiN coatings, on untreated and plasma nitrided AISI H13 steels. Knoop microhardness measurements and scratch tests were carried out to characterise the coating systems under investigation. The TiN on plasma nitrided “duplex” coatings showed better micro-abrasive wear resistance than the single-layered

J. C. A Batista; M. C Joseph; C Godoy; A Matthews

2001-01-01

269

Relation of Thermal Conductivity with Process Induced Anisotropic Void Systems in EB-PVD PYSZ Thermal Barrier Coatings  

Microsoft Academic Search

Thermal barrier coatings (TBCs) deposited by Electron-beam physical deposition (EB-PVD) protect the turbine blades situated at the high pressure sector of the aircraft and stationary turbines. It is an important task to uphold low thermal conductivity in TBCs during long-term service at elevated temperatures. One of the most promising methods to fulfil this task is to optimize the properties of

A. Flores Renteria; B. Saruhan-Brings; J. Ilavsky

2008-01-01

270

Relation of thermal conductivity with process induced anisotropic void system in EB-PVD PYSZ thermal barrier coatings  

Microsoft Academic Search

Thermal barrier coatings (TBCs) deposited by Electron-beam physical deposition (EB-PVD) protect the turbine blades situated at the high pressure sector of the aircraft and stationary turbines. It is an important task to uphold low thermal conductivity in TBCs during long-term service at elevated temperatures. One of the most promising methods to fulfil this task is to optimize the properties of

A. F. Renteria; B. Saruhan; J. Ilavsky

2007-01-01

271

A numerical study on the fatigue and rolling contact fatigue behaviour of PVD-coated steel and titanium spur gears  

Microsoft Academic Search

Thin hard coatings deposited with physical vapor deposition (PVD) can enhance both the fatigue and the rolling contact fatigue\\u000a resistance of mechanical components. In this work a cheap and fast way to evaluate the best parameter levels of coating and\\u000a bulk material is proposed. Design of Experiments (DoE) was applied to the numerical results obtained from the simulation of\\u000a meshing

Sergio Baragetti; Federico Tordini

2011-01-01

272

Evaluation of interfacial mechanical properties under shear loading in EB-PVD TBCs by the pushout method  

Microsoft Academic Search

A new simple pushout technique for evaluation of interfacial shear mechanical properties in thermal barrier coatings has been developed. The technique is similar to the pushout test of fiber-reinforced ceramics, except for the specimen shape and support method. The technique has been applied to evaluation of interfacial delamination toughness, ?i, of the electron beam physical vapor deposition (EB-PVD) ZrO2 thermal

Sang-Seok Kim; Yu-Fu Liu; Yutaka Kagawa

2007-01-01

273

Characteristics of PVdF-HFP\\/TiO 2 composite membrane electrolytes prepared by phase inversion and conventional casting methods  

Microsoft Academic Search

Porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based polymer membranes filled with various contents of titania (TiO2) nanocrystalline particles are prepared by phase inversion technique and, along with conventional casting method for comparison. N-methyl-2-pyrrolidone (NMP) as a solvent is used to dissolve the polymer and to make the slurry with TiO2. Cast film is obtained by spreading the slurry and evaporating NMP in a

Kwang Man Kim; Nam-Gyu Park; Kwang Sun Ryu; Soon Ho Chang

2006-01-01

274

Ionic conductivity and diffusion coefficient studies of PVdF–HFP polymer electrolytes prepared using phase inversion technique  

Microsoft Academic Search

A novel polymer membrane comprising poly(vinylidene difluoride hexafluoropropylene) (PVdF–HFP) copolymer was prepared by phase inversion technique with two different nonsolvents. The membranes were gelled in an electrolyte solution of 1 M of LiPF6 in EC\\/DMC and were subjected to a.c. impedance analysis at temperatures ranging from ?30 to 70 °C. The films were characterized by SEM, adsorption\\/desorption, NMR spectroscopy and

A Manuel Stephan; Yuria Saito

2002-01-01

275

Friction and wear behaviors of the PVD ZrN coated carbide in sliding wear tests and in machining processes  

Microsoft Academic Search

Medium-frequency magnetron sputtered PVD ZrN coatings were deposited on YG6 (WC+6wt% Co) cemented carbide. Microstructural and fundamental properties of the ZrN coatings were examined. Sliding wear tests against hardened steel using the ring-block method and dry machining tests on hardened steel were carried out with these coated materials. The friction coefficient and wear rates were measured. The wear surface features

Deng Jianxin; Liu Jianhua; Zhao Jinlong; Song Wenlong; Niu Ming

2008-01-01

276

Performance of PVD Coated Carbide Inserts When Machining a Nimonic (C-263) Alloy at High Speed Conditions  

Microsoft Academic Search

Physicals Vapor Deposition (PVD) coated carbide inserts were used to machine a nickel-base, C-263, superalloy under severe cutting conditions. Test results show that the TiN\\/TiCN\\/TiN coated, inserts with positive, honed and chamfered edges (Tool A) outperformed similar tools with double positive edges and no edge protection (Tool B) in terms of tool life as well as lower flank wear rate

E. O. Ezugwu; C. I. Okeke

2000-01-01

277

Characterization of PVdF-HFP\\/Nafion\\/AlO[OH] n composite membranes for direct methanol fuel cell (DMFC)  

Microsoft Academic Search

Poly-(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP)\\/Nafion ionomer\\/aluminum oxy hydroxide nanocomposite membranes were prepared by phase inversion technique. The resultant membranes were subjected to protonic conductivity, methanol permeability, infra-red and thermogravimmetric analysis. The infra-red spectroscopic measurements revealed the presence of sulfonic acid groups in the composite membranes. The thermal stability and ionic conductivity of the polymer membranes have been greatly varied upon the addition

G. Gnana Kumar; Dae Nyung Lee; Pil Kim; Kee Suk Nahm; R. Nimma Elizabeth

2008-01-01

278

Irradiated PVdF-HFP–tin oxide composite membranes for the applications of direct methanol fuel cells  

Microsoft Academic Search

Poly(styrene sulfonic acid)-grafted poly(vinylidene fluoride-co-hexafluoroproplyene)\\/tin oxide composite membranes were prepared for the direct methanol fuel cells applications. The interconnected pores of the PVdF-HFP membranes endorsed the higher poly(styrene sulfonic acid) grafting. The incorporation of tin oxide particles decreased the polymeric content volume which was available for the grafting reaction and reduced the grafting degree values. The obtained morphological and structural

G. Gnana kumar; Junhwa Shin; Young-Chang Nho; In seon Hwang; Geng Fei; Ae Rhan Kim; Kee Suk Nahm

2010-01-01

279

Structural and transport properties of porous PVdF-HFP electrolyte membranes modified with an inorganic filler  

Microsoft Academic Search

Novel porous poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) copolymer membranes were prepared with zinc chloride as an additive and silica as a ceramic filler. Porosity of the membranes was determined by Scanning Electron Microscopy (SEM). Inclusion of ceramic filler decreases the crystalline character of a polymer which facilitates the movement of ions leading to an increase in the conductivity. The infra-red spectroscopic and

G. Gnana Kumar; Dae Nyung Lee; Ae Rhan Kim; Pil Kim; Kee Suk Nahm; R. Nimma Elizabeth

2008-01-01

280

Structural characterization of PVdF-HFP\\/PEG\\/Al 2O 3 proton conducting membranes for fuel cells  

Microsoft Academic Search

Composite polymer membranes comprising of poly(vinylidene fluoride-hexafluoro propylene)\\/alumina (PVdF-HFP\\/Al2O3) were prepared by phase inversion technique with poly(ethylene glycol) (PEG) as an additive. The prepared membranes were soaked in 6M H3PO4 and were immobilized for protonic conductivity. The morphological properties of the prepared membranes were examined by scanning electron microscopy (SEM). The infra-red spectroscopic measurements revealed the presence of phosphate anions

G. Gnana Kumar; Pil Kim; Kee suk Nahm; R. Nimma Elizabeth

2007-01-01

281

Investigation of ionic conduction and mechanical properties of PMMA–PVdF blend-based polymer electrolytes  

Microsoft Academic Search

Polymeric gel electrolytes, based on a blend of poly(methylmethacrylate)\\/poly(vinylidene fluoride) (PMMA\\/PVdF), ethylene carbonate\\/propylene carbonate (EC\\/PC) as plasticizer and lithium perchlorate as electrolyte, have been studied as a function of the different polymeric ratios to obtain the best compromise between ionic conduction and mechanical properties of the systems involved. Ionic conductivity and the lithium self-diffusion coefficient were measured by the PFG–NMR

Isabella Nicotera; Luigi Coppola; Cesare Oliviero; Marco Castriota; Enzo Cazzanelli

2006-01-01

282

Impact of ethylene carbonate on ion transport characteristics of PVdF–AgCF 3SO 3 polymer electrolyte system  

Microsoft Academic Search

The ionic transport in thin film plasticized polymer electrolytes based on polyvinylidene fluoride (PVdF) as the polymer host, silver triflate (AgCF3SO3) as salt and ethylene carbonate (EC) as plasticizer prepared by solution casting technique has been reported. Addition of silver triflate has resulted in an increase in the room temperature (298K) electrical conductivity of the polymer from 10?6 to 10?5Scm?1

S. Austin Suthanthiraraj; D. Joice Sheeba; B. Joseph Paul

2009-01-01

283

An investigation of PVdF\\/PVC-based blend electrolytes with EC\\/PC as plasticizers in lithium battery applications  

Microsoft Academic Search

Solid polymer electrolytes (SPEs) composed of poly(vinylidene fluoride) (PVdF)–poly(vinyl chloride) (PVC) complexed with lithium perchlorate (LiClO4) as salt and ethylene carbonate (EC)\\/propylene carbonate (PC) as plasticizers were prepared using solvent-casting technique, with different weight ratios of EC and PC. The amorphicity and complexation behavior of the polymer electrolytes were confirmed using X-ray diffraction (XRD) and FTIR studies. TG\\/DTA and scanning

S. Rajendran; P. Sivakumar

2008-01-01

284

Wear mechanisms and tool performance of TiAlN PVD coated inserts during machining of AISI 4140 steel  

Microsoft Academic Search

The tribological influences of PVD-applied TiAlN coatings on the wear of cemented carbide inserts and the microstructure wear behaviors of the coated tools under dry and wet machining are investigated. The turning test was conducted with variable high cutting speeds ranging from 210 to 410m\\/min. The analyses based on the experimental results lead to strong evidences that conventional coolant has

Samir K. Khrais; Y. J. Lin

2007-01-01

285

The effect of coating thickness on the thermal conductivity of EB-PVD PYSZ thermal barrier coatings  

Microsoft Academic Search

The effect of coating thickness on thermal conductivity of electron beam physical vapor deposited (EB-PVD) partially Y2O3 stabilized ZrO2 (PYSZ) thermal barrier coatings (TBCs) was investigated. Two-layer samples, PYSZ coating deposited on nickel-base superalloy IN625 substrate with a 50 ?m NiCoCrAlY bond coat, as well as free-standing PYSZ coatings and quasi-free-standing PYSZ coatings (PYSZ on transparent sapphire) were included in

H.-J. Rätzer-Scheibe; U. Schulz; T. Krell

2006-01-01

286

Evolution of photo-stimulated luminescence of EB-PVD\\/(Ni, Pt)Al thermal barrier coatings  

Microsoft Academic Search

Experiments are described which were designed to assess the suitability of photo-stimulated luminescence piezo-spectroscopy (PLPS) measurements as a basis for non-destructive inspection (NDI) and determination of life remaining of thermal barrier coatings (TBCs). Thermal cyclic tests were conducted on 7wt.% Y2O3 stabilized ZrO2 (YSZ) electron beam physical vapor deposited (EB-PVD)\\/(Ni, Pt)Al\\/CMSX-4 TBCs at two temperatures 1151 and 1121°C. The evolution

Mei Wen; Eric H. Jordan; Maurice Gell

2005-01-01

287

Evaluation of interface degradation during cyclic oxidation of EB-PVD thermal barrier coatings and correlation with TGO luminescence  

Microsoft Academic Search

The typical degradation mechanism of EB-PVD thermal barrier coatings (TBCs) that occurs during cyclic furnace testing of a commercial 7YSZ coating on a single-crystal nickel-base superalloy is analyzed. The mechanism includes local separation of the ceramic top coat from the thermally grown oxide (TGO), growth of the separated regions along the coating–substrate interface, and, upon reaching a critical size, large-scale

V. K. Tolpygo; D. R. Clarke; K. S. Murphy

2004-01-01

288

Optimized multilayer oxalate biosensor.  

PubMed

The optimization of a biosensor prepared by the immobilization of oxalate oxidase (OOX) with a cross-linking agent onto a multilayer inorganic/organic modified electrode, is presented. A very thin Prussian Blue (PB) film covered by a self-doped polyaniline (SPAN) layer acts as very sensitive amperometric sensor for the H(2)O(2) formed by the enzymatic reaction. The electrode allows the very reliable and sensitive oxalate detection in the 0.08 to 0.45mmoll(-1) concentration range. The observed sensitivity was 131.3muAmmol(-1)cm(-2) at the operation potential of 0.05V versus Ag/AgCl in a succinate buffer solution (pH=3.8). The bilayer Prussian blue/SPAN leads to a very stable, sensitive and selective system that not only minimizes the interference caused by ascorbic and uric acids but also forms a very adherent sensing film that allows repetitive successive determinations. PMID:18969343

Fiorito, Pablo A; Córdoba de Torresi, Susana I

2004-02-27

289

Microstructural analyses and wear behavior of the cemented carbide tools after laser surface treatment and PVD coating  

NASA Astrophysics Data System (ADS)

Adhesion is one of the most important characteristics of coating on cutting tools. Poor coating adhesion on the tool favors fragmentation and release of hard abrasive particles between the tool and the workpiece. These particles interact with the surfaces of the tool, accelerating its wear and decreasing tool life. One possible solution is the use of laser texturing prior to coating in order to achieve a desired surface topography with enhanced adhesion properties. In the texturing, a high-frequency short-pulse laser changes surface characteristics, generating resolidified material and selective vaporization. This work evaluated the effectiveness of laser texturing in improving the substrate-coating adhesion of PVD coated cemented carbide tools. To this end, the substrates were textured with a Nd:YAG laser, in four different intensities, and then coated with a PVD TiAlN film. To ascertain the effectiveness of laser texturing, Rockwell C indentation and turning experiments were performed on both textured tools and conventional unlasered tools. The PVD coated laser-textured tool showed better performance in the indentation and turning tests than the standard tools. A comparative evaluation of tool wear mechanisms indicated that texturing did not change the wear mechanisms, but altered their importance to tool wear. The anchoring provided by the higher roughness of the textured surface increased the adhesion of the coating on the substrate, thus increasing tool life. Additionally, the chemical modification of the carbide grains due to the laser heating might be responsible for an enhanced adhesion between coating and substrate.

Neves, Davi; Diniz, Anselmo Eduardo; Lima, Milton Sérgio Fernandes

2013-10-01

290

Blending effect of poly (ethyl methacrylate) on lithium bis(perfluoroethanesulfonyl) imide-ferroceramic PVdF-HFP composite  

NASA Astrophysics Data System (ADS)

PEMA as a supportive host matrix is physically blended in five different proportions with PVdF-HFP based system containing LiBETI as a electrolyte, EC / DMC mixture in 1:1 v/v ratio as a plasticizer and BaTiO3 as a filler for improving ionic conductivity is attempted. The A.C impedance, DSC, and FTIR studies are carried out. The ionic conductivity measurements on these Polymer Blend Nano Composites(PBNC) showed that blending improved ionic conductivity, and enhancement in magnitude is observed for 22.5% PEMA blended PVdF-HFP (7.5 wt%) system with 7.5% BaTiO3. The DSC showed PEMA interaction with PVDF causing reorientation of VDF crystals and resulting conformational changes showed variations in melting endotherms, are observed. FTIR studies identified PEMA interaction with plasticizer and PVdF-HFP through the change in the C-F stretching and C=O Carbonyl bond.

Vickraman, P.; Jayaraman, R.; Purushothaman, K.

2013-06-01

291

The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings  

SciTech Connect

Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The density of the APS coatings was controlled by varying the spray parameters. The low density APS yttria-partially stabilized zirconia (yttria-PSZ) coatings yielded a thermal conductivity that is lower than both the high density APS coatings and the EB-PVD coatings. The thermal aging of both fully and partially stabilized zirconia are compared. The thermal conductivity of the coatings permanently increases upon exposure to high temperatures. These increases are attributed to microstructural changes within the coatings. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the EB-PVD coatings are less susceptible to thermal aging effects, results suggest that they typically have a higher thermal conductivity than APS coatings before thermal aging. The increases in thermal conductivity due to thermal aging for plasma sprayed partially stabilized zirconia have been found to be less than for plasma sprayed fully stabilized zirconia coatings.

Dinwiddie, R.B.; Beecher, S.C.; Porter, W.D. [Oak Ridge National Lab., TN (United States); Nagaraj, B.A. [General Electric Co., Cincinnati, OH (United States). Aircraft Engine Group

1996-05-01

292

Spin-reorientation transition in Co/Pt multilayers on nanospheres  

SciTech Connect

Co/Pt multilayers have been deposited onto self-assembled arrays of spherical particles. The radial film thickness variation changes both the magnitude and direction of the magnetic anisotropy within a single cap. By adjusting the thickness of the Co layers, we produced caps that exhibit a reorientation of the magnetization from in plane at the center toward out of plane at the rim within a distance of less than 100 nm. The domain configuration and its reversal behavior in applied magnetic fields were studied with high spatial resolution scanning transmission x-ray microscopy, providing quantitative insight into nanoscale magnetism.

Eimueller, T. [Junior Research Group Magnetic Microscopy, Experimental Physics, University of Bochum, D-44780 Bochum (Germany); Ulbrich, T. C.; Guhr, I. L. [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Amaladass, E. [Max-Planck-Institute for Metals Research, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Tyliszczak, T. [Advanced Light Source (ALS), LBNL, 1 Cyclotron Road, Berkeley, California 94720 (United States); Albrecht, M. [Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany)

2008-04-01

293

Numerical investigations of failure in EB-PVD thermal barrier coating systems  

Microsoft Academic Search

Thermal barrier coating (TBC) systems are used in high temperature applications in turbine engines. TBCs are applied on superalloy substrates and are multilayered coatings comprised of a metallic bond coat, a thermally grown oxide (TGO) and a ceramic top coat. They provide thermal protection for the superalloy substrate and are considered to hold the greatest potential for increased operating temperatures.

Michael L. Glynn

2003-01-01

294

Micromagnetic modelling of multilayer media  

NASA Astrophysics Data System (ADS)

A micromagnetic model for the calculation of magnetization processes in magnetic multilayer systems has been developed using a finite element method. Shell elements which account for the multilayer structure and a magnetic vector potential to treat long-range dipolar interactions are the essential features of the algorithm. Micromagnetic calculations of hysteresis properties and domain structures in Co/Pt multilayer systems show a qualitative agreement with magnetic images obtained from field emission Lorentz microscopy. The nucleation field of Co/Pt multilayers increases with improving texture. Spatial fluctuations of the magneto-crystalline anisotropy energy create barriers for domain wall motion. The pinning field of domains increases with increasing grain size. The domain wall structure depends on he local magnetocrystalline anisotropy. The wall structure changes from a Bloch-type to a Néel-type wall as the local anisotropy constant decreases. The quality of texture and the grain size significantly influence the jaggedness of domains in Co/Pt multilayers. Large grains and strong deviations of the easy directions from the film normal deteriorate the smoothness of domains and increase the transition width.

Schrefl, T.; Fidler, J.; Chapman, J. N.

1996-09-01

295

Multilayer perceptron for nonlinear programming.  

SciTech Connect

A new method for solving nonlinear programming problems within the framework of a multilayer neural network perceptron is proposed. The method employs the Penalty Function method to transform a constrained optimization problem into a sequence of unconstrained optimization problems and then solves the sequence of unconstrained optimizations of the transformed problem by training a series of multilayer perceptrons. The neural network formulation is represented in such a way that the multilayer perceptron prediction error to be minimized mimics the objective function of the unconstrained problem, and therefore, the minimization of the objective function for each unconstrained optimization is attained by training a single perceptron. The multilayer perceptron allows for the transformation of problems with two-sided bounding constraints on the decision variables x, e.g., a{<=}x{sub n}{<=}b, into equivalent optimization problems in which these constraints do not explicitly appear. Hence, when these are the only constraints in the problem, the transformed problem is constraint free (i.e., the transformed objective function contains no penalty terms) and is solved by training a multilayer perceptron only once. In addition, we present a new Penalty Function method for solving nonlinear programming problems that is parameter free and guarantees that feasible solutions are obtained when the optimal solution is on the boundary of the feasible region. Simulation results, including an example from operations research, illustrate the proposed methods.

Reifman, J.; Feldman, E. E.; Reactor Analysis

2002-08-01

296

Molecular Photovoltaics in Nanoscale Dimension  

PubMed Central

This review focuses on the intrinsic charge transport in organic photovoltaic (PVC) devices and field-effect transistors (SAM-OFETs) fabricated by vapor phase molecular self-assembly (VP-SAM) method. The dynamics of charge transport are determined and used to clarify a transport mechanism. The 1,4,5,8-naphthalene-tetracarboxylic diphenylimide (NTCDI) SAM devices provide a useful tool to study the fundamentals of polaronic transport at organic surfaces and to discuss the performance of organic photovoltaic devices in nanoscale. Time-resolved photovoltaic studies allow us to separate the charge annihilation kinetics in the conductive NTCDI channel from the overall charge kinetic in a SAM-OFET device. It has been demonstrated that tuning of the type of conductivity in NTCDI SAM-OFET devices is possible by changing Si substrate doping. Our study of the polaron charge transfer in organic materials proposes that a cation-radical exchange (redox) mechanism is the major transport mechanism in the studied SAM-PVC devices. The role and contribution of the transport through delocalized states of redox active surface molecular aggregates of NTCDI are exposed and investigated. This example of technological development is used to highlight the significance of future technological development of nanotechnologies and to appreciate a structure-property paradigm in organic nanostructures.

Burtman, Vladimir; Zelichonok, Alexander; Pakoulev, Andrei V.

2011-01-01

297

Design and fabrication of heat resistant multilayers  

SciTech Connect

Many promising applications of multilayer x-ray optical elements subject them to intense radiation. This paper discusses the selection of optimal pairs of materials to resist heat damage and presents simulations of multilayer performance under extreme heat loadings.

Thorne, J.M.; Knight, L.V.; Peterson, B.G.; Perkins, R.T.; Gray, K.J.

1986-01-01

298

Selecting Optimal Experiments For Feedforward Multilayer Perceptrons.  

National Technical Information Service (NTIS)

Where should a researcher conduct experiments to provide training data for a multilayer perceptron. This question is investigated and a statistically-based method for optimally selecting experimental design points for multilayer perceptrons is introduced....

L. M. Belue

1995-01-01

299

Unfolding single- and multilayers  

NASA Astrophysics Data System (ADS)

When planar structures (e.g. sedimentary layers, veins, dykes, cleavages, etc.) are subjected to deformation, they have about equal chances to be shortened or stretched. The most common shortening and stretching structures are folds and boudinage, respectively. However, boudinage requires additional deformation mechanisms apart from viscous flow, like formation of fractures or strain localization. When folded layers are subjected to extension, they could potentially unfold back to straight layers. Although probably not uncommon, this would be difficult to recognize. Open questions are whether folded layers can unfold, what determines their mechanical behaviour and how we can recognize them in the field. In order to approach these questions, we present a series of numerical experiments that simulate stretching of previously folded single- and multi-layers in simple shear, using the two dimensional numerical modelling platform ELLE, including the finite element module BASIL that calculates viscous deformation. We investigate the parameters that affect a fold train once it rotates into the extensional field. The results show that the unfolding process strongly depends on the viscosity contrast between the layer and matrix (Llorens et al., 2013). Layers do not completely unfold when they experience softening before or during the stretching process or when other neighbouring competent layers prevent them from unfolding. The foliation refraction patterns are the main indicators of unfolded folds. Additionally, intrafolial folds and cusp-like folds adjacent to straight layers, as well as variations in fold amplitudes and limb lengths of irregular folds can also be used as indicators of stretching of a layer after shortening and folding. References: Llorens, M-.G., Bons, P.D., Griera, A. and Gomez-Rivas, E. 2013. When do folds unfold during progressive shear?. Geology, 41, 563-566.

Llorens, Maria-Gema; Bons, Paul D.; Griera, Albert; Gomez-Rivas, Enrique

2014-05-01

300

Electrochemical properties of multilayer film assembled by layer-by-layer adsorption of redox polymer  

NASA Astrophysics Data System (ADS)

A redox polymer, poly(ethylenimine)ferrocene (PEI-Fc) was prepared by attaching electroactive ferrocene groups to the backbone of a water soluble, biocompatible polyelectrolyte, poly(ethylenimine), and multilayer film composed of polystyrenesulfonate sodium (PSS) and PEI-Fc was prepared by alternate layer-by-layer (LBL) self-assembly adsorption technique based on the electrostatic force between the opposite charges carried by these two polymers. UV-Vis spectra was used to monitor the LBL process, and the thickness and immobilization amount of each layer were characterized by quartz crystal microbalance (QCM), which showed the formation of nano-scale multilayer structure and linear mass increase dependent on the alternate adsorption cycles. The electrochemical properties of the PEI-Fc/PSS multilayer film modified gold electrode were investigated by cyclic voltammetry. It was observed clearly that the electrochemical properties of this multilayer film were strongly dependent on the layer number and the ferrocene content in PEI-Fc. The electrochemical kinetic was analyzed based on a general model for surface process, and the experimental data fitted well with that evaluated from the above model. This redox polymer showed potential for the construction of reagentless biosensor.

Sun, Tao; Zheng, Haitao; Liu, Shiyang; Liu, Pu; Zhou, Jingli; Suye, Shin-Ichiro

2009-07-01

301

Perfect absorption in graphene multilayers  

NASA Astrophysics Data System (ADS)

We demonstrate that 100% light absorption can be achieved in a graphene-based hyperbolic metamaterial, consisting of periodically arranged graphene layers which are tilted with respect to the interface. The geometrical parameters of the multilayered structure and the chemical potential of graphene are chosen in such a way that the in-plane relative effective permittivity is close to -1. Under this condition, the graphene multilayer exhibits asymmetry which appears as a very large difference between waves propagating upward and downward with respect to multilayer boundaries. One of them has a very high attenuation constant and neither of the waves undergo reflection at slab interfaces, resulting in total absorption even for an optically ultra-thin slab.

Nefedov, Igor S.; Valaginnopoulos, Constantinos A.; Melnikov, Leonid A.

2013-11-01

302

Magnetic Alloys in Nanoscale Biomaterials  

SciTech Connect

Fe-Co composition gradient and Fe-Pt multilayer alloy films were tested as catalysts for growing vertically aligned carbon nanofibers (VACNFs) by plasma-enhanced chemical vapor deposition (PECVD). The Fe-Co film yielded nanofibers with alloy tips in a wide compositional range varying from 8.15 pct Fe at the Co-rich end to 46.29 pct Fe in the middle of the wafer as determined by energy-dispersive X-ray analysis. Two Fe-Co cubic phases (SG Pm3m, Pm{bar 3}m) were identified by preliminary X-ray diffraction (XRD) measurements. Magnetic measurements showed a substantially greater hysteresis loop area and coercivity in Fe-Co catalyst nanoparticles as compared to the as deposited Fe-Co film. The Fe-Pt film did not break into FePt alloy nanoparticles under the applied processing parameters and thus the utility of FePt as a VACNF catalyst has been inconclusive.

Leventouri, T. H. [Florida Atlantic University; Melechko, Anatoli Vasilievich [ORNL; Sorge, Korey D. [Florida Atlantic University; Klein, Kate L [ORNL; Fowlkes, Jason Davidson [ORNL; Rack, P. D. [University of Tennessee, Knoxville (UTK); Anderson, Ian M [ORNL; Thompson, James R [ORNL; McKnight, Timothy E [ORNL; Simpson, Michael L [ORNL

2006-01-01

303

Stress analysis in multilayer structures  

NASA Astrophysics Data System (ADS)

The magnitude and distribution of thermal stresses in multilayer thin film structures have been modeled using a analytical solution method (ASM) and a newly developed hybrid finite element method (HFEM). This combined approach treats stress singularity as well as nonsingularity with equal ease. The use of hybrid elements based on an analytical solution of the stress singularity at the free edge has been found to provide accurate thermal stress solutions with fast convergence. Modeling of stress behavior in multilayer structures has been extended to include solutions for non-90sp° wedges (so called sharp edges) and solutions for multimaterial wedges. The dependence of the order of the stress singularity as well as the intensity of the stress singularity on the specific free edge geometry has been worked out as well. The results of theoretical analysis and calculations have made feasible the development of a software program, titled "Multilayer Structures" (MLS). The program is Windows-based. It is user friendly, allowing efficient and rapid thermal stress analysis of virtually any multilayer structure. It is seen as a valuable tool in design and for manufacturing and quality control functions in areas in which multilayer structures play a vital role. With a specially designed automesh engine and a simplified procedure for residual stress calculations, tedious preprocessing procedures need not be of concern. The program still provides the opportunity to use conventional finite element analysis. The MLS program has been applied and evaluated in various areas, such as in the optimization of substrate and film thicknesses in Multi Chip Modules (MCM's), the design of functionally gradient transition layers required in the bonding of dissimilar materials, and the identification of suitable substrates or buffer layers in diamond film deposition. The work reported in this dissertation constitutes a first step towards a full understanding of the mechanical behavior of multilayer structures and the development of a complete and comprehensive tool to predict performance.

White, Dongming Yuan

1997-12-01

304

Feature Selection Using a Multilayer Perceptron  

Microsoft Academic Search

The problem of selecting the best set of features for target r ecognition using a multilayer perceptron is addressed in this paper. A technique has been developed which analyzes the weights in a multilayer perceptron to determine which features the network finds important and which are unimportant. A brief introduction to the use of multilayer perceptrons for classification and the

Dennis W. Ruck; Steven K. Rogers; Matthew Kabrisky

1990-01-01

305

Effect of Hf Additions to Pt Aluminide Bond Coats on EB-PVD TBC Life  

NASA Technical Reports Server (NTRS)

Small Hf additions were incorporated into a Pt aluminide coating during chemical vapor deposition (CVD) on single crystal RENE N5 substrates. Standard yttria-stabilized zirconia top coats were subsequently deposited onto the coated substrates by electron beam-physical vapor deposition (EB-PVD). The coated substrates underwent accelerated thermal cycle testing in a furnace at a temperature in excess of 1121 C (2050 F) (45 minute hot exposure, 15 minute cool to approximately 121 C (250 F)) until the thermal barrier coating (TBC) failed by spallation. Incorporating Hf in the bond coat increased the TBC life by slightly more than three times that of a baseline coating without added Hf. Scanning electron microscopy of the spalled surfaces indicated that the presence of the Hf increased the adherence of the thermally grown alumina to the Pt aluminide bond coat. The presence of oxide pegs growing into the coating from the thermally grown alumina may also partially account for the improved TBC life by creating a near-surface layer with a graded coefficient of thermal expansion.

Nesbitt, James; Nagaraj, Ben; Williams, Jeffrey

2000-01-01

306

Surface properties of Mo-implanted PVD TiN coatings using MEVVA source  

NASA Astrophysics Data System (ADS)

To further improve the tribological properties of TiN coatings used on mechanical parts, Mo ions were implanted into PVD TiN coatings with Metal Vapor Vacuum Arc (MEVVA) source at the implantation dose as high as 1 × 1018 ions/cm2. Surface morphology, microstructures, and nano-hardness of TiN coatings were investigated by optical profilometer, X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), and Nano Indenter System. The tribological properties were investigated on a ball-on-disk friction and wear tester. The XRD results demonstrated that the diffraction peak of Ti2N appeared in the Mo-implanted TiN coatings. However, there was obvious decrease of nano-hardness due to the soft Molybdenum phase and its oxides. It was approved that Mo-implanted TiN coatings could greatly improve their tribological properties and that the implantation at dose of 1 × 1018 ions/cm2 could result in much lower friction coefficient. The existence of soft molybdenum, lubricious molybdenum oxides and titanium oxides resulted in the remarkable reducing of the friction coefficient of TiN coatings with Mo-implantation.

Tian, Bin; Yue, Wen; Fu, Zhiqiang; Gu, Yanhong; Wang, Chengbiao; Liu, Jiajun

2013-09-01

307

Effect of Bond Coat Materials on Thermal Fatigue Failure of EB-PVD Thermal Barrier Coatings  

NASA Astrophysics Data System (ADS)

Effect of MCrAlY bond coat alloy systems on thermal fatigue failure of thermal barrier coatings (TBCs) was investigated, where the TBC specimen consisted of Ni-based superalloy IN738LC substrate, bond coat, and 8 wt.% Y2O3-stabilized ZrO2 (YSZ) top coat. The top coat was fabricated by EB-PVD method with 250 ?m in thickness. Three kinds of MCrAlY alloys were studied as the bond coat material. Employing the originally developed test equipment, thermal fatigue tests were carried out, by applying thermal cycles between 400 and 950°C in air. Special attention was paid not only to the failure life of the TBC specimen, but also the underlying failure mechanisms. The experimental results clearly demonstrated that the effect of MCrAlY bond coat alloys on the thermal fatigue life was very significant. Some discussions were made on the experimental results based on the measurements of mechanical and metallurgical properties of the bond coat alloys: i.e., elastic stiffness, thermal expansion coefficient and high temperature oxidation resistance.

Yamagishi, Satoshi; Okazaki, Masakazu; Sakaguchi, Motoki; Matsubara, Hideaki

308

Properties of Al doped zinc oxide films prepared by electron beam-PVD  

NASA Astrophysics Data System (ADS)

Al doped ZnO (AZO) films were prepared on quartz substrates by the co-evaporation of ZnO and Al2O3 ingots by EB-PVD. EB power applied to the Al2O3 source was ranged from 3kW to 10kW, while EB power to the ZnO source was fixed at 3kW, at a substrate temperature of 400°C. X-ray diffraction measurement showed that the AZO films were weakly c-axis oriented. Transmittance of All the AZO films was over 80% in the visible range. Highest reflectance in the near IR range was obtained at the EB power on Al2O3 of 5kW. The lowest resistivity of 3.05 × 10-4 ?cm was obtained for the film deposited with the EB power on Al2O3 of 5kW with the deposition time of 300s.

Yamaguchi, N.; Kuroyama, T.; Okuhara, Y.; Matsubara, H.

2011-10-01

309

Thermocyclic behavior of variously stabilized EB-PVD thermal barrier coatings  

SciTech Connect

The demand for increasing gas inlet temperatures in modern gas turbines up to 1,500 C and above is the main reason for the need for more reliable thermal barrier coatings. New ceramics should provide higher phase stability and better resistance against chemical attack by pollutants in the combustion gas. Electron beam-- physical vapor deposition (EB-PVD) processed, ZrO{sub 2}-based TBCs were generated on bond-coated superalloy directionally solidified (DS) samples. Common yttria-stabilized zirconias of two different compositions, as well as novel stabilizers like CeO{sub 2} and La{sub 2}O{sub 3}, were investigated. A columnar structure was established during high-rate deposition in all cases. Diameter, degree of ordering of the columns, and phase composition depended on stabilizer oxide and content. The role of differences of vapor pressures is addressed with regard to chemical homogeneity of the coatings. The performance of the TBCs having various stabilizers was investigated in a cyclic oxidation furnace test and in a burner rig at Mach 0.3. The results were correlated to the type and content of stabilizer with special emphasis on phase analyses. Evaporation of new ceramic compositions necessitates special precautions because the vapor pressures of the components may differ too much. A new dual-source evaporation coater allows the production of these innovative TBCs with close control of chemistry. The potential of the equipment will be discussed.

Schulz, U.; Fritscher, K.; Peters, M. [German Aerospace Research Establishment, Cologne (Germany). Inst. of Materials Research

1997-10-01

310

Ionic liquid-polymer gel electrolytes based on morpholinium salt and PVdF(HFP) copolymer  

NASA Astrophysics Data System (ADS)

New ionic liquid-polymer gel electrolytes (IPGEs) are prepared from N-ethyl- N-methylmorpholinium bis(trifluoromethanesulfonyl)imide (Mor 1,2TFSI) and poly(vinylidene fluoride)-hexafluoropropylene copolymer (PVdF(HFP)). To investigate the effect of propylene carbonate (PC) on the ionic conductivity of the IPGEs, the preparation methods are roughly divided into two groups according to the presence or absence of PC. The ionic conductivity for each IPGE is measured with increasing temperature and changing weight ratio of Mor 1,2TFSI. The results show that the ionic conductivity increases as the temperature and weight ratio of the Mor 1,2TFSI increase, and that the added PC improves the ionic conductivity of the IPGEs. In addition, thermogravimetric analysis and the data from infrared spectroscopy demonstrate the thermal stability of each IPGE and the presence of PC in the polymer network. Although the IPGEs that contain PC display high conductivity (˜1.1 × 10 -2 S cm -1) at 60 °C, they are thermally unstable.

Kim, Ki-Sub; Park, Seung-Yeob; Choi, Sukjeong; Lee, Huen

311

Image quality of figured multilayered optics  

SciTech Connect

The reflectivity and resolution of a multilayer structure is strongly affected by the roughness at the interfaces between two successive layers and by the amount that the constituent materials will diffuse into one another at the interfaces. Performance is also affected by the variations in individual layer thicknesses and by inhomogeneities in the materials. These deviations from the ideal multilayer will also affect the quality of the image from a figured multilayer optical element. The theory used to model the effects of non-ideal multilayers on the image quality of figured optics will be discussed. The relationship between image quality and multilayer structure quality will be illustrated with several examples.

Peterson, B.G.; Knight, L.V.; Pew, H.K.

1985-01-01

312

Elemental distributions and substrate rotation in industrial TiAlN\\/VN superlattice hard PVD coatings  

Microsoft Academic Search

Chemical distribution of individual layers within a TiAlN\\/VN multilayer structure was characterised using a field emission gun transmission electron microscope, coupled with energy-filtered elemental mapping and high-angle annular dark field imaging. Bright field TEM micrographs using zero-loss electrons indicated the presence of alternating TiAlN and VN layers with a periodicity of ?3 nm. Electron spectroscopic images (ESI) using the Ti-L2,3

Z. Zhou; B. Rother; A. P. Ehiasarian; P. Eh Hovsepian; W.-D. Munz

2004-01-01

313

Bench-scale synthesis of nanoscale materials  

NASA Technical Reports Server (NTRS)

A novel flow-through hydrothermal method used to synthesize nanoscale powders is introduced by Pacific Northwest Laboratory. The process, Rapid Thermal Decomposition of precursors in Solution (RTDS), uniquely combines high-pressure and high-temperature conditions to rapidly form nanoscale particles. The RTDS process was initially demonstrated on a laboratory scale and was subsequently scaled up to accommodate production rates attractive to industry. The process is able to produce a wide variety of metal oxides and oxyhydroxides. The powders are characterized by scanning and transmission electron microscopic methods, surface-area measurements, and x-ray diffraction. Typical crystallite sizes are less than 20 nanometers, with BET surface areas ranging from 100 to 400 sq m/g. A description of the RTDS process is presented along with powder characterization results. In addition, data on the sintering of nanoscale ZrO2 produced by RTDS are included.

Buehler, M. F.; Darab, J. G.; Matson, D. W.; Linehan, J. C.

1994-01-01

314

Multilayer printed wiring board lamination  

SciTech Connect

The relationship of delamination resistance of multilayer PWBs made from GF material to manufacturing process variables was investigated. A unique quantitative test method developed during this project shows that delamination resistance is highly sensitive to material conditioning, to innerlayer surface treatment, and to post-lamination storage conditions, but is relatively insensitive to cure cycle variations.

Lula, J.W.

1980-06-01

315

A multilayered neural network controller  

Microsoft Academic Search

A multilayered neural network processor is used to control a given plant. Several learning architectures are proposed for training the neural controller to provide the appropriate inputs to the plant so that a desired response is obtained. A modified error-back propagation algorithm, based on propagation of the output error through the plant, is introduced. The properties of the proposed architectures

Demetri Psaltis; Athanasios Sideris; Alan A. Yamamura

1988-01-01

316

Engineered interfaces and nano-scale thin films for solid oxide fuel cell electrolytes  

NASA Astrophysics Data System (ADS)

Solid state electrolytes with high oxygen ionic conductivity at low temperatures are required to develop cost effective and efficient solid oxide fuel cells. This study investigates the influence of engineered interfaces on the oxygen ionic conductivity of nano-scale multilayer thin film electrolytes. The epitaxial Sm2O3 doped CeO2 (SDC) and Sc2O3 stabilized ZrO2 (ScSZ) are selected as the alternative layers for the proposed multilayer thin film electrolyte based on the optimum structural, chemical, and electrical properties reported in the previous studies. The epitaxial SDC(111)/ScSZ(111) multilayer thin films are grown on high purity Al2O3(0001) substrates by oxygen-plasma assisted molecular beam epitaxy. Prior to the deposition of multilayers, the growth parameters are optimized for epitaxial CeO 2, ZrO2, SDC, and ScSZ thin films. The epitaxial orientation and surface morphology of CeO2 thin films shows dependency on the growth rate. Epitaxial CeO2(111) is obtained at relatively high growth rates (>9 A/min) at a substrate temperature of 650°C and an oxygen partial pressure of 2 x 10 -5 Torr. The same growth parameters are used for the deposition of ZrO2 thin films. ZrO2 exhibits both monoclinic and cubic phases, which is stabilized in the cubic structure by doping with Sc 2O3. The Sm and Sc evaporation rates are varied during the growth to obtain thin films of 15 mol % SmO1.5 doped CeO2 and 20 mol % ScO1.5 stabilized ZrO2, respectively. The SDC/ScSZ multilayer thin films are grown using the same growth parameters by varying the number of layers. The SDC/ScSZ multilayer thin films show significant enhancement in the oxygen ionic conductivity in comparison to single layer SDC and ScSZ thin films. The increase in the oxygen ionic conductivity with the increase in number of layers can be attributed to lattice mismatch induced ionic conductivity along the interfaces. The 8-layer film exhibits the maximum oxygen ionic conductivity with one order of magnitude enhancement in the temperature range of 500-800°C compared to single layer thin films.

Nandasiri, Manjula I.

317

Second-order nonlinear optical characteristics of nanoscale self-assembled multilayer organic films  

Microsoft Academic Search

Ionically self-assembled monolayer (ISAM) films are typically an assemblage of oppositely charged polymers built layer by layer through Coulombic attraction utilizing an environmentally friendly process to form ordered structures that are uniform, molecularly smooth and physically robust. ISAM films have been shown to be capable of the noncentrosymmetric order requisite for a second-order nonlinear optical response with excellent temporal and

Patrick J. Neyman

2004-01-01

318

Atomistic Design and Simulations of Nanoscale Machines and Assembly  

NASA Technical Reports Server (NTRS)

Over the three years of this project, we made significant progress on critical theoretical and computational issues in nanoscale science and technology, particularly in:(1) Fullerenes and nanotubes, (2) Characterization of surfaces of diamond and silicon for NEMS applications, (3) Nanoscale machine and assemblies, (4) Organic nanostructures and dendrimers, (5) Nanoscale confinement and nanotribology, (6) Dynamic response of nanoscale structures nanowires (metals, tubes, fullerenes), (7) Thermal transport in nanostructures.

Goddard, William A., III; Cagin, Tahir; Walch, Stephen P.

2000-01-01

319

Magnetic properties of nanoscale conductors  

NASA Astrophysics Data System (ADS)

This doctoral dissertation examines some magnetic properties of nanoscale conductors. It comprises two classes of problems, namely, the response of closed nanoscopic systems to an external magnetic field, and the magnetization dependent transport of nanomagnets. In the first class of closed nanoscopic structures like quantum dots or metal grains, the system has discrete energy levels which can be modeled by Random Matrix Theory. The addition of a magnetic field is analyzed using a crossover random matrix model. In Chapter 2, we show that in the crossover there exist correlations between elements of the same eigenvector and between different eigenvectors. We show that these correlations between different eigenvectors lead to enhanced fluctuations of the electron-electron interaction matrix elements which are absent in the pure ensembles. In Chapter 3, we generalize these results to analyze the magnetic field response of energy levels in ultrasmall metal grains. We present a theory of mesoscopic fluctuations of g tensors and avoided crossing energies in a, small metal grain that contains both orbital and spin contributions to the g tensor. In the second class of problems we study two effects in small ferromagnets where the charge transport is coupled to the magnetization. In Chapter 4, we show that a sufficiently large unpolarized current can cause a spin-wave instability in a nanomagnet with asymmetric contacts. The dynamics beyond the instability is calculated analytically in the perturbative regime of small spinwave amplitudes, and numerically for larger currents. In Chapter 5, we study "anisotropic magnetoresistance fluctuations" which is the ferromagnetic analog of the well-known Universal Conductance; Fluctuations in metals. The conductance of a ferromagnetic particle depends on the relative orientation of the magnetization with respect to the direction of current flow. This phenomenon is known as "anisotropic magnetoresistance" and has no counterpart in normal-metal conductors. We show that quantum interference leads to an additional, random yet (statistically) universal dependence of the conductance of a ferromagnet on the magnetization direction. The mechanism for these anisotropic magnetoresistance fluctuations is the interplay of spin-orbit scattering, random impurity scattering, and the ferromagnet's exchange field.

Adam, Shaffique

320

High performance EUV multilayer optics  

NASA Astrophysics Data System (ADS)

The demand for enhanced optical resolution in order to structure and observe ever smaller details has pushed optics development in recent years. There is increasing interest in optical components for the extreme ultraviolet (EUV) spectral region mainly as a result of the production of more powerful electronic circuits with the aid of projection lithography. Due to absorption at wavelengths below 100 nm the penetration depth of EUV radiation into matter is only a few nano-meters. Hence, reflective optics must be used for imaging and light collection such as EUV multilayer mirrors which consist of alternating thin films with different refractive indices. This basic idea can be compared to the classic, high reflective ?/4 systems: the constructive interference of all beams reflected at the film interfaces. At Fraunhofer IOF Jena multilayer optics development cover the full range between the soft X-rays around 2 nm wave-length and the vacuum ultraviolet. However, the paper will focus on multilayer optics for EUV lithography applications at 13.5 nm. Besides the development of high-reflective multilayers with enhanced thermal and radiation stability using interface engineering and optimized capping layers collector and imaging optics for diverse applications in the EUV spectral range have been realized. The deposition of EUV collector mirrors for high-power laser produced plasma (LPP) sources is discussed. The paper summarizes recent progress and the present knowledge in preparation and characterization of multilayer optics for the EUV spectral range with regard to maximum optical performance, minimization of structure imperfections, reduc-tion of residual stresses as well as enhanced thermal and radiation stability.

Kaiser, Norbert; Yulin, Sergiy; Perske, Marco; Feigl, Torsten

2008-09-01

321

Tunable nanoscale-effecient plasmonic demultiplexers  

NASA Astrophysics Data System (ADS)

The importance of wavelength division demultiplexers (WDM) reside in its aggressive use in many areas of industry which are based on signal processing, especially in the fields of telecommunications, optical computing, integrated photonics circuits and sensing applications. Plasmonic wavelength division demultiplexers are essential component for on chip nanoscale plasmonic systems. In this work, we present nanoscale plasmonic wavelength-selective demultiplexer based on feedback resonator. The devices are based on a thin layer of silver with waveguides etched onto it having small foorprint. These devices can be easily tuned to any specific wavelength in the IR range.

Azzazi, Abdulilah; Swillam, Mohamed A.

2014-03-01

322

Induced transparency in nanoscale plasmonic resonator systems.  

PubMed

An optical effect analogous to electromagnetically induced transparency (EIT) is observed in nanoscale plasmonic resonator systems. The system consists of a slot cavity as well as plasmonic bus and resonant waveguides, where the phase-matching condition of the resonant waveguide is tunable for the generation of an obvious EIT-like coupled resonator-induced transparency effect. A dynamic theory is utilized to exactly analyze the influence of physical parameters on transmission characteristics. The transparency effect induced by coupled resonance may have potential applications for nanoscale optical switching, nanolaser, and slow-light devices in highly integrated optical circuits. PMID:21847218

Lu, Hua; Liu, Xueming; Mao, Dong; Gong, Yongkang; Wang, Guoxi

2011-08-15

323

Multilayer Composite Pressure Vessels  

NASA Technical Reports Server (NTRS)

A method has been devised to enable the fabrication of lightweight pressure vessels from multilayer composite materials. This method is related to, but not the same as, the method described in gMaking a Metal- Lined Composite-Overwrapped Pressure Vessel h (MFS-31814), NASA Tech Briefs, Vol. 29, No. 3 (March 2005), page 59. The method is flexible in that it poses no major impediment to changes in tank design and is applicable to a wide range of tank sizes. The figure depicts a finished tank fabricated by this method, showing layers added at various stages of the fabrication process. In the first step of the process, a mandrel that defines the size and shape of the interior of the tank is machined from a polyurethane foam or other suitable lightweight tooling material. The mandrel is outfitted with metallic end fittings on a shaft. Each end fitting includes an outer flange that has a small step to accommodate a thin layer of graphite/epoxy or other suitable composite material. The outer surface of the mandrel (but not the fittings) is covered with a suitable release material. The composite material is filament- wound so as to cover the entire surface of the mandrel from the step on one end fitting to the step on the other end fitting. The composite material is then cured in place. The entire workpiece is cut in half in a plane perpendicular to the axis of symmetry at its mid-length point, yielding two composite-material half shells, each containing half of the foam mandrel. The halves of the mandrel are removed from within the composite shells, then the shells are reassembled and bonded together with a belly band of cured composite material. The resulting composite shell becomes a mandrel for the subsequent steps of the fabrication process and remains inside the final tank. The outer surface of the composite shell is covered with a layer of material designed to be impermeable by the pressurized fluid to be contained in the tank. A second step on the outer flange of each end fitting accommodates this layer. Depending on the application, this layer could be, for example, a layer of rubber, a polymer film, or an electrodeposited layer of metal. If the fluid to be contained in the tank is a gas, then the best permeation barrier is electrodeposited metal (typically copper or nickel), which can be effective at a thickness of as little as 0.005 in (.0.13 mm). The electrodeposited metal becomes molecularly bonded to the second step on each metallic end fitting. The permeation-barrier layer is covered with many layers of filament-wound composite material, which could be the same as, or different from, the composite material of the inner shell. Finally, the filament-wound composite material is cured in an ov

DeLay, Tom

2005-01-01

324

Relation of Thermal Conductivity with Process Induced Anisotropic Void Systems in EB-PVD PYSZ Thermal Barrier Coatings  

SciTech Connect

Thermal barrier coatings (TBCs) deposited by Electron-beam physical deposition (EB-PVD) protect the turbine blades situated at the high pressure sector of the aircraft and stationary turbines. It is an important task to uphold low thermal conductivity in TBCs during long-term service at elevated temperatures. One of the most promising methods to fulfil this task is to optimize the properties of PYSZ-based TBC by tailoring its microstructure. Thermal conductivity of the EB-PVD produced PYSZ TBCs is influenced mainly by the size, shape, orientation and volume of the various types of porosity present in the coatings. These pores can be classified as open (inter-columnar and between feather arms gaps) and closed (intra-columnar pores). Since such pores are located within the three-dimensionally deposited columns and enclose large differences in their sizes, shapes, distribution and anisotropy, the accessibility for their characterization is very complex and requires the use of sophisticated methods. In this work, three different EB-PVD TBC microstructures were manufactured by varying the process parameters, yielding various characteristics of their pores. The corresponding thermal conductivities in as-coated state and after ageing at 11000C/1h and 100h were measured via Laser Flash Analysis Method (LFA). The pore characteristics and their individual effect on the thermal conductivity are analysed by USAXS which is supported by subsequent modelling and LFA methods, respectively. Evident differences in the thermal conductivity values of each microstructure were found in as-coated and aged conditions. In summary, broader columns introduce higher values in thermal conductivity. In general, thermal conductivity increases after ageing for all three investigated microstructures, although those with initial smaller pore surface area show smaller changes.

Renteria, A. Flores; Saruhan-Brings, B.; Ilavsky, J.

2008-03-03

325

Characterization of ceramic PVD thin films on AZ31 magnesium alloys  

NASA Astrophysics Data System (ADS)

Ceramic thin films have been widely used to protect the metal substrate as coatings in the past years. In order to improve the poor corrosion resistance of AZ31 magnesium alloy, the study in this paper used the electron beam evaporation method to prepare ceramic PVD films on its surface with TiO 2 and Al 2O 3 as donors, respectively. Atomic force microscopy (AFM), scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), Auger electron spectroscopy (AES) and X-ray diffraction (XRD) were used to investigate the surface morphology, composition and microstructure of the thin films. Both films deposited on AZ31 took on compact top surface morphologies and grew as amorphous structures on substrate. AES test not only showed that films compositions deviated the standard stoichiometric ratios, but also found that element Mg diffused into films and existed as magnesium oxide in the TiO x film as well as the AlO x film. In the electrochemical corrosion test, the AlO x coating on AZ31 exhibited the largest electrochemical impedance in a 3.5% NaCl solution. But it did not show better corrosion resistance than others for the poorer adhesion. Even if its thickness was small, the TiO x coating on AZ31 exhibited the best corrosion resistance in this study. According to the observation and analysis, the damage of these films on AZ31 in aggressive solutions was mainly due to the existence of pores, microcracks, vacancies and poor adhesion between coating and substrate.

Wu, Guosong; Zeng, Xiaoqin; Ding, Wenbin; Guo, Xingwu; Yao, Shoushan

2006-08-01

326

Cycling behavior of poly(vinylidene fluoride-hexafluoro propylene) (PVdF-HFP) membranes prepared by phase inversion method  

Microsoft Academic Search

A novel highly porous poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) membrane was prepared by phase inversion method with 1-butanol or methanol as non-solvent. These films where characterized by ionic conductivity, SEM and nitrogen adsorption\\/desorption analysis. The prepared membranes were employed as separator in LiAl0.01Co0.99O2\\/Li cells and their charge–discharge performances are presented. Although, these membranes vary slightly in the physical properties like, morphology and

A Manuel Stephan; N. G Renganathan; S Gopukumar; Dale-Teeters

2004-01-01

327

Characterization of PVdF-HFP polymer membranes prepared by phase inversion techniques I. Morphology and charge–discharge studies  

Microsoft Academic Search

A novel nanoporous polymer membrane comprised of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) co-polymer was prepared by phase inversion techniques using two different non-solvents. The films were subjected to scanning electron microscope (SEM) and nitrogen adsorption\\/desorption analysis. The morphology and porosity of the membranes are correlated with the chemical structure of the non-solvents used. Also, nanoparticle LiCr0.01Mn1.99O4 cathode material was prepared by solid-state

A. Manuel Stephan; Dale Teeters

2003-01-01

328

Nanofiller incorporated poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP) composite electrolytes for lithium batteries  

Microsoft Academic Search

Composite polymer electrolyte (CPE) membranes, comprising poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP), aluminum oxyhydroxide (AlO[OH]n) of two different sizes 7?m\\/14nm and LiN(C2F5SO2)2 as the lithium salt were prepared using a solution casting technique. The prepared membranes were subjected to XRD, impedance spectroscopy, compatibility and transport number studies. Also Li Cr0.01Mn1.99O4\\/CPE\\/Li cells were assembled and their charge–discharge profiles made at 70°C. The incorporation of

A. Manuel Stephan; Kee Suk Nahm; T. Prem Kumar; M. Anbu Kulandainathan; G. Ravi; J. Wilson

2006-01-01

329

Electrochemical studies on nanofiller incorporated poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP) composite electrolytes for lithium batteries  

Microsoft Academic Search

Composite polymer electrolytes (CPE), comprising poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP), aluminum oxyhydroxide, (AlO[OH]\\u000a n\\u000a – of 40 nm and 7 ?m) as filler and LiN(C2F5SO2)2 or LiClO4 as lithium salt were prepared using a solution casting technique. The membranes were subjected to XRD, impedance spectroscopy, compatibility and transport number studies. The incorporation of nanofiller greatly enhanced the ionic conductivity and the compatibility of the

A. Manuel Stephan; Kee Suk Nahm; M. Anbu Kulandainathan; G. Ravi; J. Wilson

2006-01-01

330

Electrochemical redox supercapacitors using PVdF-HFP based gel electrolytes and polypyrrole as conducting polymer electrode  

Microsoft Academic Search

Electrochemical redox supercapacitors have been fabricated using polymeric gel electrolytes polyvinylidene fluoride co-hexafluoropropylene (PVdF-HFP)–ethylene carbonate (EC)–propylene carbonate (PC)–MClO4: M=Li, Na, (C2H5)4N and electrochemically deposited polypyrrole as conducting polymer electrode. The performance of the capacitors have been characterized using a.c impedance spectroscopy, cyclic linear sweep voltammetry and galvanostatic charge–discharge techniques. The capacitors shows larger values of overall capacitance of about 14–25 mF

S. K. Tripathi; Ashok Kumar; S. A. Hashmi

2006-01-01

331

Rheological properties and impedance spectroscopy of PMMA-PVdF blend and PMMA gel polymer electrolytes for advanced lithium batteries  

Microsoft Academic Search

In the present study, blend ionic conducting membranes formed by poly(methylmethacrylate (PMMA) \\/ poly(vinilydenefluoride)\\u000a (PVDF) (blend ratio PMMA\\/PVdF=80\\/20), lithium perchlorate (LiClO4) as a salt and a mixture of ethylene carbonate (EC)-propylene carbonate (PC) as plasticizer are prepared and characterized\\u000a by impedance spectroscopy and dynamic rheological experiments. We compared the results obtained on the blends with those on\\u000a PMMA gel-based polymer

I. Nicotera; L. Coppola; C. Oliviero; G. A. Ranieri

2005-01-01

332

Characterization of poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP) electrolytes complexed with different lithium salts  

Microsoft Academic Search

Poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP) gel electrolytes comprising a combination of plasticizers, ethylene carbonate (EC) and propylene carbonate (PC) and lithium salt LiX (X=BF4-,CF3SO3-,ClO4-) have been prepared using the solution casting technique in an argon atmosphere. The prepared electrolytes were subjected to ionic conductivity, compatibility with lithium metal anode and thermogravimetric (TG)\\/differential thermal analysis (DTA). The membranes, which possess lithium salt, LiBF4

A. Manuel Stephan; S. Gopu Kumar; N. G. Renganathan; M. Anbu Kulandainathan

2005-01-01

333

New liquid crystal-embedded PVdF- co -HFP-based polymer electrolytes for dye-sensitized solar cell applications  

Microsoft Academic Search

Liquid crystal (LC; E7 and\\/or ML-0249)-embedded, poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-co-HFP)-based, polymer electrolytes were prepared for use in dye-sensitized solar cells (DSSCs). The electrolytes contained\\u000a 1-methyl-3-propylimidazolium iodide (PMII), tetrabutylammonium iodide (TBAI), and iodine (I\\u000a 2), which participate in theI\\u000a 3\\u000a ? \\/I\\u000a ? redox couple. The incorporation of photochemically stable PVdF-co-HFP in the DSSCs created a stable polymer electrolyte that resisted leakage and

G. Vijayakumar; Meyoung Jin Lee; Myungkwan Song; Sung-Ho Jin; Jae Wook Lee; Chan Woo Lee; Yeong-Soon Gal; Hyo Jin Shim; Yongku Kang; Gi-Won Lee; Kyungkon Kim; Nam-Gyu Park; Suhkmann Kim

2009-01-01

334

EB-PVD Y 2O 3- and CeO 2 Y 2O 3 -stabilized zirconia thermal barrier coatings — crystal habit and phase composition  

Microsoft Academic Search

ZrO2-based ingot sources with stabilizing oxides of 6.5 and 20 wt.% Y2O3 and 252.5 wt.% CeO2Y2O3 respectively were used to deposit thermal barrier coatings (TBCs) on rotating cylindrical electron beam physical vapour deposition (EB-PVD) NiCoCrAlY-coated IN 100 substrates by reactive high rate EB-PVD. The TBCs were investigated by scanning electron microscopy, X-ray fluorescence and X-ray diffraction. The phases within the

U. Schulz; K. Fritscher; M. Peters

1996-01-01

335

Magnetoresistive phenomena in nanoscale magnetic systems  

Microsoft Academic Search

Nanomagnetic materials are playing an increasingly important role in modern technologies. A particular area of interest involves the interplay between magnetism and electric transport, i.e. magnetoresistive properties. Future generations of field sensors and memory elements will have to be on a length scale of a few nanometers or smaller. Magnetoresistive properties of such nanoscale objects exhibit novel features due to

John D. Burton

2008-01-01

336

Traceable nanoscale measurement at NML-SIRIM  

NASA Astrophysics Data System (ADS)

The role of national metrology institute (NMI) has always been very crucial in national technology development. One of the key activities of the NMI is to provide traceable measurement in all parameters under the International System of Units (SI). Dimensional measurement where size and shape are two important features investigated, is one of the important area covered by NMIs. To support the national technology development, particularly in manufacturing sectors and emerging technology such nanotechnology, the National Metrology Laboratory, SIRIM Berhad (NML-SIRIM), has embarked on a project to equip Malaysia with state-of-the-art nanoscale measurement facility with the aims of providing traceability of measurement at nanoscale. This paper will look into some of the results from current activities at NML-SIRIM related to measurement at nanoscale particularly on application of atomic force microscope (AFM) and laser based sensor in dimensional measurement. Step height standards of different sizes were measured using AFM and laser-based sensors. These probes are integrated into a long-range nanoscale measuring machine traceable to the international definition of the meter thus ensuring their traceability. Consistency of results obtained by these two methods will be discussed and presented. Factors affecting their measurements as well as their related uncertainty of measurements will also be presented.

Dahlan, Ahmad M.; Abdul Hapip, A. I.

2012-06-01

337

Nanoscale pore formation dynamics during aluminum anodization  

Microsoft Academic Search

A theoretical analysis of nanoscale pore formation during anodization reveals its fundamental instability mechanism to be a field focusing phenomenon when perturbations on the minima of the two oxide interfaces are in phase. Lateral leakage of the layer potential at high wave number introduces a layer tension effect that balances the previous destabilizing effect to produce a long-wave instability and

Sunil Kumar Thamida; Hsueh-Chia Chang

2002-01-01

338

Nanoscale dispensing of liquids through cantilevered probes  

Microsoft Academic Search

Nanoscale dispensing is a novel technique to deposit material and create structures at dimensions of 100 nm and below. It has great flexibility in feature shape and choice of deposited material. Due to its potential low cost and lack of time consuming steps, it represents an interesting complementary tool to standard lithographic processes. The key feature of nanodispensing is deposition

A. Meister; S. Jeney; M. Liley; T. Akiyama; U. Staufer; N. F. de Rooij; H. Heinzelmann

2003-01-01

339

Fats, Oils, & Colors of a Nanoscale Material  

ERIC Educational Resources Information Center

Phase changes and intermolecular forces are important physical science concepts but are not always easy to present in an active learning format. This article presents several interactive activities in which students plot the melting points of some fatty acids and explore the effect that the nanoscale size and shape of molecules have on the…

Lisensky, George C.; Horoszewski, Dana; Gentry, Kenneth L.; Zenner, Greta M.; Crone, Wendy C .

2006-01-01

340

Enhanced nanoscale friction on fluorinated graphene.  

PubMed

Atomically thin graphene is an ideal model system for studying nanoscale friction due to its intrinsic two-dimensional (2D) anisotropy. Furthermore, modulating its tribological properties could be an important milestone for graphene-based micro- and nanomechanical devices. Here, we report unexpectedly enhanced nanoscale friction on chemically modified graphene and a relevant theoretical analysis associated with flexural phonons. Ultrahigh vacuum friction force microscopy measurements show that nanoscale friction on the graphene surface increases by a factor of 6 after fluorination of the surface, while the adhesion force is slightly reduced. Density functional theory calculations show that the out-of-plane bending stiffness of graphene increases up to 4-fold after fluorination. Thus, the less compliant F-graphene exhibits more friction. This indicates that the mechanics of tip-to-graphene nanoscale friction would be characteristically different from that of conventional solid-on-solid contact and would be dominated by the out-of-plane bending stiffness of the chemically modified graphene. We propose that damping via flexural phonons could be a main source for frictional energy dissipation in 2D systems such as graphene. PMID:22720882

Kwon, Sangku; Ko, Jae-Hyeon; Jeon, Ki-Joon; Kim, Yong-Hyun; Park, Jeong Young

2012-12-12

341

Direct temperature mapping of nanoscale plasmonic devices.  

PubMed

Side by side with the great advantages of plasmonics in nanoscale light confinement, the inevitable ohmic loss results in significant joule heating in plasmonic devices. Therefore, understanding optical-induced heat generation and heat transport in integrated on-chip plasmonic devices is of major importance. Specifically, there is a need for in situ visualization of electromagnetic induced thermal energy distribution with high spatial resolution. This paper studies the heat distribution in silicon plasmonic nanotips. Light is coupled to the plasmonic nanotips from a silicon nanowaveguide that is integrated with the tip on chip. Heat is generated by light absorption in the metal surrounding the silicon nanotip. The steady-state thermal distribution is studied numerically and measured experimentally using the approach of scanning thermal microscopy. It is shown that following the nanoscale heat generation by a 10 mW light source within a silicon photonic waveguide the temperature in the region of the nanotip is increased by ? 15 °C compared with the ambient temperature. Furthermore, we also perform a numerical study of the dynamics of the heat transport. Given the nanoscale dimensions of the structure, significant heating is expected to occur within the time frame of picoseconds. The capability of measuring temperature distribution of plasmonic structures at the nanoscale is shown to be a powerful tool and may be used in future applications related to thermal plasmonic applications such as control heating of liquids, thermal photovoltaic, nanochemistry, medicine, heat-assisted magnetic memories, and nanolithography. PMID:24422562

Desiatov, Boris; Goykhman, Ilya; Levy, Uriel

2014-02-12

342

Luminescence and Scintillation Properties at the Nanoscale  

Microsoft Academic Search

This contribution is a review of the luminescence and scintillation properties of nanoparticles (NP), particularly doped insulators. Luminescence spectroscopy is an appropriate tool to probe matter at the nanoscale. Luminescence is also the last stage of the scintillation process. Specific surface and structural effects occurring in NP are reported. Their consequences on the NP luminescence properties are discussed. Parts of

Christophe Dujardin; David Amans; Andrei Belsky; Frederic Chaput; Gilles Ledoux; Anne Pillonnet

2010-01-01

343

On Information Assurance in Nanoscale Networks  

Microsoft Academic Search

An intersection of two worlds, emerging nano- technologies and network\\/communication theory, is poised to change the nature of information assurance. New communication paradigms will be derived from the transition from micro- to nano-scale devices. The related degrees of freedom and constraints associated with these new technologies will change our notions about efficient networks, system design and the nature of information

Stephen F. Bush

344

Probing and manipulating magnetization at the nanoscale  

NASA Astrophysics Data System (ADS)

Combining semiconductors with magnetism in hetero- and nano-structured geometries provides a powerful means of exploring the interplay between spin-dependent transport and nanoscale magnetism. We describe two recent studies in this context. First, we use spin-dependent transport in ferromagnetic semiconductor thin films to provide a new window into nanoscale magnetism [1]: here, we exploit the large anomalous Hall effect in a ferromagnetic semiconductor as a nanoscale probe of the reversible elastic behavior of magnetic domain walls and gain insight into regimes of domain wall behavior inaccessible to more conventional optical techniques. Next, we describe novel ways to create self-assembled hybrid semiconductor/ferromagnet core-shell nanowires [2] and show how magnetoresistance measurements in single nanowires, coupled with micromagnetic simulations, can provide detailed insights into the magnetization reversal process in nanoscale ferromagnets [3]. The work described here was carried out in collaboration with Andrew Balk, Jing Liang, Nicholas Dellas, Mark Nowakowski, David Rench, Mark Wilson, Roman Engel-Herbert, Suzanne Mohney, Peter Schiffer and David Awschalom. This work is supported by ONR, NSF and the NSF-MRSEC program.[4pt] [1] A. L. Balk et al., Phys. Rev.Lett. 107, 077205 (2011).[0pt] [2] N. J. Dellas et al., Appl. Phys. Lett. 97, 072505 (2010).[0pt] [3] J. Liang et al., in preparation.

Samarth, Nitin

2012-02-01

345

Dynamic structural disorder in supported nanoscale catalysts.  

PubMed

We investigate the origin and physical effects of "dynamic structural disorder" (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale. PMID:24712802

Rehr, J J; Vila, F D

2014-04-01

346

Dynamic structural disorder in supported nanoscale catalysts  

NASA Astrophysics Data System (ADS)

We investigate the origin and physical effects of "dynamic structural disorder" (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale.

Rehr, J. J.; Vila, F. D.

2014-04-01

347

Fats, Oils, and Colors of Nanoscale Materials  

NSDL National Science Digital Library

Phase changes and intermolecular forces are important physical science concepts but are not always easy to present in an active learning format. This article presents several interactive activities in which students plot the melting points of some fatty acids and explore the effect that the nanoscale size and shape of molecules have on the material's macroscopic phase properties.

Horoszewski, Dana; Lisensky, George C.; Zenner, Greta M.; Gentry, Kenneth L.; Crone, Wendy C.

2006-12-01

348

Introduction to Nanoscale Science and Technology  

Microsoft Academic Search

Nanoscale science and technology is a young, promising field that encompasses a wide range of disciplines including physics, chemistry, biology, electrical engineering, chemical engineering, and materials science. With rapid advances in areas such as molecular electronics, synthetic biomolecular motors, DNA-based self-assembly, and manipulation of individual atoms, nanotechnology has captured the attention and imagination of researchers and the general public. Introduction

Massimiliano di Ventra; Stephane Evoy; James R. Heflin Jr.

2004-01-01

349

Strongly Interacting Systems at the Nanoscale.  

National Technical Information Service (NTIS)

The Final Proceedings for Strongly Interacting Systems at the Nanoscale, 8 August 2005 - 12 August 2005. The purpose of the meeting is to bring together the communities of two different fields of solid-state physics, namely those of mesoscopic physics and...

B. Altshuler C. Marcus N. Andrei G. Shlyapnikov Y. Nazarov

2006-01-01

350

Electroluminescence from Au/(nanoscale Ge/nanoscale SiO2) superlattices/p-Si  

NASA Astrophysics Data System (ADS)

Nanoscale Ge/nanoscale SiO2 superlattices (SLs) with four periods have been grown using the two-electron-beam alternation evaporating technique. Visible electroluminescence (EL) from the semitransparent Au film/(nanoscale Ge/nanoscale SiO2) SL/p-Si structures was observed when the forward bias exceeded 5 V, and their EL power efficiencies were significantly higher than that of a semitransparent Au film/nanoscale Ge particles embedded SiO2 film/p-Si structure. The effects of thicknesses of nanoscale Ge layers in the SLs and of annealing temperatures on the EL were studied. It is found that the intensity and position of the major EL peak being located in a range of 640-680 nm vary synchronously, while the EL shoulder around 520 nm remains unchanged in wavelength with increasing Ge layer thickness. The results strongly support the viewpoint that EL originates from the luminescence centers in the SiO2 layers.

Qin, G. G.; Heng, C. L.; Bai, G. F.; Wu, K.; Li, C. Y.; Ma, Z. C.; Zong, W. H.; You, Li-Ping

1999-12-01

351

Thermal conduction in graphene and graphene multilayers  

NASA Astrophysics Data System (ADS)

There has been increasing interest in thermal conductivity of materials motivated by the heat removal issues in electronics and by the need of fundamental science to understand heat conduction at nanoscale [1, 2, 3]. This dissertation reports the results of the experimental investigation of heat conduction in graphene and graphene multilayers. Graphene is a planar single sheet of sp2-bonded carbon atoms arranged in honeycomb lattice. It reveals many unique properties, including the extraordinarily high carrier mobility. In order to measure the thermal conductivity of graphene we developed an original non-contact technique based on micro-Raman spectroscopy. The samples for this study were prepared by mechanical exfoliation and suspended across trenches in Si/SiO2 substrates. The number of atomic planes was determined by deconvolution of the Raman 2D band. The suspended graphene flakes attached to the heat sinks were heated by the laser light focused in the middle. The Raman G peak's temperature sensitivity allowed us to monitor the local temperature change produced by the variation of the excitation laser power. A special calibration procedure was developed to determine the fraction of power absorbed by graphene. Our measurements revealed that single-layer graphene has an extremely high room-temperature thermal conductivity in the range 3800-5300 W/mK depending on the flake size and quality. It was also found that most of the heat near room temperature is transferred by acoustic phonons rather than electrons. Theoretical studies of the phonon thermal conduction in graphene, which included detail treatment of the Umklapp scattering, are in agreement with our experiments. The measurements were also extended to few-layer graphene. It was shown that the thermal conductivity reduces with the increasing number of layers approaching the bulk graphite limit. To validate the measurement technique we investigated the thermal conductivity of the polycrystalline graphene films and reduced graphene oxide films deposited on polyethylene terephthalate substrates. In this case we obtained much smaller values of thermal conductivity, which was explained by the strong acoustic phonon scattering on the grain boundaries. Obtained results are important for electronic applications of graphene and may lead to new methods of thermal management of nanoelectronic chips.

Ghosh, Suchismita

352

Unfolding the damping behavior of multilayer graphene membrane in the low-frequency regime.  

PubMed

The damping behavior of few-layered graphene membrane in the low-frequency regime of mechanical loading is investigated in the present study. Damping of graphene has significant applications in micro/nanoscale devices and macroscale dynamic systems for absorbing shock-generated energies. Damping behavior of graphene is experimentally evaluated, for the first time, by dynamic mechanical analysis at the nanoscale with cyclic mechanical loading in the range 0.1-50 ?N applied at a frequency range of 10-250 Hz. This study reveals 260% higher damping on graphene membranes than a silicon surface. The damping shows excellent reproducibility and remains steady even after 100,000 cycles. The damping of multilayer graphene membrane, supported on a Si/SiO(2) substrate, shows a strong dependence on the frequency of cyclic loading. The mechanism governing impressive damping of a graphene membrane is elucidated by structural changes such as ripple formation, ripple wave propagation, and z-axis compression. Damping behavior of a graphene membrane in this low-frequency regime is also found to depend on the number of graphene layers and is explained as the interplay between in-plane sp(2) and out-of-plane van der Waals forces. These findings are important for establishing the potential of graphene for applications in macro- to nanoscale structures that require continuous absorption of shock waves without destruction/failure. PMID:22519730

Lahiri, Debrupa; Das, Santanu; Choi, Wonbong; Agarwal, Arvind

2012-05-22

353

Nano- and sub-micron porous polyelectrolyte multilayer assemblies: biomimetic surfaces for human corneal epithelial cells.  

PubMed

In vivo, corneal epithelial cells adhere on basement membranes that exhibit porosity on the nanoscale with the diameters of pores and fibers ranging from 20 to 200 nm. Polyelectrolyte multilayers with porosity ranging from the nano to the microscale were assembled to mimic the pore sizes of corneal membranes in vivo. The average pore diameter was found to be 100 nm and 600 nm for the nanoporous and sub-micron porous films respectively. In this study, a purely physical feature, specifically, porosity, provided cues to human corneal epithelial cells. Porous surfaces that exhibited either 100 nm or 600 nm pore diameters supported corneal cell adhesion, however, nanoscale porosity significantly enhanced corneal epithelial cellular response. Corneal epithelial cell proliferation and migration speeds were significantly higher on nanoporous topographies. The actin cytoskeletal organization was well defined and vinculin focal adhesions were found in cells presented with a nanoscale environment. These trends prevailed for fibronectin-coated surfaces as well suggesting that for human corneal epithelial cells, the physical environment plays a defining role in guiding cell behavior. PMID:19446874

Hajicharalambous, Christina S; Lichter, Jenny; Hix, William T; Swierczewska, Magdalena; Rubner, Michael F; Rajagopalan, Padmavathy

2009-08-01

354

Nanoscale precipitation in hot rolled sheet steel  

NASA Astrophysics Data System (ADS)

Some newer hot rolled high strength low alloy (HSLA) steels with a single phase ferrite matrix have obtained substantial strengthening from nanoscale precipitation. These HSLA are reported to have a good combination of strength, ductility and hole-expansion ability. In the current work, Gleeble ® 3500 torsion testing was employed to simulate the hot rolling process with varying run-out table cooling rates and coiling temperatures on five microalloyed steels with additions of Ti, Nb, Mo, Cr and V, to investigate the effects of microalloy additions and processing conditions on microstructures as well as mechanical properties. Subsized tensile specimens obtained from as-twisted torsion samples were used to evaluate mechanical properties. The precipitation states of the five steels with different processing conditions were characterized using extraction replica TEM. Comparison of microstructures and mechanical properties was discussed. Characterization of the microstructure via light optical microscopy showed the matrix microstructure was mainly influenced by coiling temperature, which indicates that the transformation from austenite to ferrite occurred during the coiling period. A higher Ti content was shown to reduce the second constituent fractions. Investigation of carbon extraction replica specimens via TEM revealed the presence of nanoscale precipitation. Extensive nanoscale precipitation was observed in most of the specimens having a polygonal ferrite matrix, while in the granular bainite/ferrite microstructure at lower temperatures, fewer microalloy carbides were present. The specimens with polygonal ferrite had similar or higher yield strength than the specimens with granular bainite microstructure, which suggests the effectiveness of precipitation strengthening from extensive nanoscale precipitates. In the Nb-Mo steel, more significant strengthening due to grain refinement was evident. Yield strength values were less than reported for JFE's "NANOHITEN®" steel in specimens with similar microstructure (polygonal ferrite matrix with extensive nanoscale precipitation).

Sun, Jun

355

Developed player for multilayer disk  

NASA Astrophysics Data System (ADS)

Based on nm fabrication technology, a developed player for dual and multilayer disk is proposed in this paper. A multifocus device with focus 8.5 mm is used. The distance between two neighbor focal plane is 0.45 mm. The numeral aperture of the developed player is 0.59, the focusing spot is 0.93 um. The developed player with the multifocus device is not only simple in structure, light in weight, but also can focus automatically at any layer of multilayer disk eve, no mechanical movement. Compared to the common CD player, the developed player is characteristic of only one multifocus device to focus and split beam, where the prism and the grating in common CD player are displaced, but the focusing and the tracing error signals can be obtained conveniently for servo detection.

Huang, Guoliang; Xu, Duanyi; Pan, Longfa; Lu, Dajin; Qi, Guosheng

1996-09-01

356

Multilayer coatings on figured optics  

Microsoft Academic Search

Soft X-Ray Projection Lithography (SXPL) will reqire uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f{sup {number_sign}}) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f{sup {number_sign}}3.4 and f{sup {number_sign}}6 optics 5 and 7.5 cm in diameter using planar

S. P. Vernon; D. G. Stearns; R. S. Rosen; N. M. Ceglio; D. P. Gaines; M. Krumrey; P. Mueller

1991-01-01

357

Multilayer coatings on figured optics  

Microsoft Academic Search

Soft x-ray projection lithography (SXPL) requires uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f 3.4 and f 6 optics 5 and 7.5 cm in diameter using planar dc magnetron

Stephen P. Vernon; Daniel G. Stearns; Robert S. Rosen; Natale M. Ceglio; David P. Gaines; Michael K. Krumrey; Peter Mueller

1992-01-01

358

Multilayer coatings on figured optics  

Microsoft Academic Search

Soft X-Ray Projection Lithography (SXPL) will reqire uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f{sup {number sign}}) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f{sup {number sign}}3.4 and f{sup {number sign}}6 optics 5 and 7.5 cm in

S. P. Vernon; D. G. Stearns; R. S. Rosen; N. M. Ceglio; D. P. Gaines; M. Krumrey; P. Mueller

1991-01-01

359

Casting Of Multilayer Ceramic Tapes  

NASA Technical Reports Server (NTRS)

Procedure for casting thin, multilayer ceramic membranes, commonly called tapes, involves centrifugal casting at accelerations of 1,800 to 2,000 times normal gravitational acceleration. Layers of tape cast one at a time on top of any previous layer or layers. Each layer cast from slurry of ground ceramic suspended in mixture of solvents, binders, and other components. Used in capacitors, fuel cells, and electrolytic separation of oxygen from air.

Collins, Earl R., Jr.

1991-01-01

360

Metallurgical phases and their magnetism at the interface of nanoscale MgB2/Fe layered structures  

NASA Astrophysics Data System (ADS)

We report on the characterization of metallurgical phases and their magnetism at the interfaces of nanoscale MgB2/Fe layered structures. MgB2/57Fe multilayers with varying layer thicknesses were prepared by vacuum deposition and investigated, before and after annealing by electrical resistance measurements, x-ray diffraction and 57Fe conversion-electron Mössbauer spectroscopy (CEMS) down to 5 K. Interfacial Fe-B phases, such as Fe2B, were identified by CEMS. A superparamagnetic-to-ferromagnetic transition is observed with increasing 57Fe film thickness. Ultrahigh vacuum annealing at 500?°C of the multilayers leads to strong diffusion of Fe atoms into the boundary regions of the MgB2 layers. MgB2 in the as-grown multilayers is non-superconducting. Structural disorder and the effect of Fe interdiffusion contribute to the suppression of superconductivity in the MgB2 films of all the as-grown multilayers and the thinner annealed multilayers. However, an annealed MgB2/57Fe/MgB2 trilayer with thicker (500 Å) MgB2 layers is observed to be superconducting with an onset temperature of 25 K. At 5 K, the annealed trilayer can be conceived as being strongly chemically modulated, consisting of two partially Fe-doped superconducting MgB2 layers separated by an interdiffused weakly magnetic Fe-B interlayer, which is characterized by a low hyperfine magnetic field Bhf of ˜11 T. This chemically modulated layer structure of the trilayer after annealing was verified by Rutherford backscattering.

Sahoo, B.; Keune, W.; Kuncser, V.; Becker, H.-W.; Röhlsberger, R.

2011-11-01

361

Multilayered Transducers Using Polyurea Film  

NASA Astrophysics Data System (ADS)

We have been investigating ultrasonic transducers using a polyurea piezoelectric material, which is fabricated by vapor deposition. To enhance the transducer performance, a multilayered configuration is studied in this work. First, the fabrication and transducer design of the multilayered structure are described. A special twin-vacuum chamber is used for laminating the polyurea layers and aluminum electrodes alternately without breaking vacuum. We fabricate two- and four-layered transducers with 1.5 ?m polyurea films. The calculation results show that the force factor and electromechanical coupling coefficient increase as the number of layers increases. Second, to evaluate the transducer performance, we measure the electromechanical coupling factors and electric admittances. The coupling coefficients also increase as the number of layers increases at the resonant frequencies of about 30, 65, and 100 MHz. The pulse/echo measurements are conducted to determine the transmission and receiving characteristics using a reflector. The results of the experiment show that the voltage amplitudes of the received signal increase because of multilayer lamination.

Nakazawa, Marie; Tabaru, Masaya; Nakamura, Kentaro; Ueha, Sadayuki; Maezawa, Akihiro

2007-07-01

362

Mössbauer and Structural Studies of f.c.c. Fe-Ni-C-based PVD CAE Coatings  

NASA Astrophysics Data System (ADS)

The physical vapor deposition by cathode arc evaporation (PVD CAE) technique in microdrops mode was applied for deposition of austenitic nanocrystalline coatings of the Fe-31.2%Ni-2%Co-0.002%Y and Fe-31.4%Ni-2%Co-0.72%C-0.001%Y alloys on Cu substrate. The Mössbauer spectroscopy, X-ray diffraction analysis, transmission electron microscopy and dilatometry have been used to study the structure, magnetic order and thermal expansion of coatings. The estimated coherently diffracting domains values (CDD) and the TEM data testify that austenitic structure in coatings is dispersed and the presence of carbon intensifies the dispersion process of structural elements. Mössbauer analysis has shown that PVD CAE process results in the decomposition of an austenitic solid solution on microareas enriched both in Ni and Co and in Fe, which leads to the formation of a specific magnetic order characterized by existence of the ferromagnetic low-moment (FM LM) and antiferomagnetic high-moment (AM HM) phases and provides stable Invar properties of a coating at the 110-400 K temperatures.

Nadutov, V. M.; Panarin, V. Ye.; Kosintsev, S. G.; Kramar, O. V.; Svystunov, Ye. O.; Volosevich, P. Yu.

2008-10-01

363

Preparation of porous, chemically cross-linked, PVdF-based gel polymer electrolytes for rechargeable lithium batteries  

NASA Astrophysics Data System (ADS)

This study reports the development of a new system of porous, chemically cross-linked, gel polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer as a polymer matrix, polyethylene glycol (PEG) as a plasticizer, and polyethylene glycol dimethacrylate (PEGDMA) as a chemical cross-linking oligomer. The electrolytes are prepared by a combination of controlled evaporation and thermal polymerization of PEGDMA. PVdF-HFP/PEG/PEGDMA gel polymer electrolytes with a composition of 5/3/2 exhibit both high ambient ionic conductivity, viz., >1 mS cm -1, and a high tensile modulus of 52 MPa, because of their porous and network structures. All the blends of electrolytes are electrochemically stable up to 5 V versus Li/Li + in the presence of 1 M LiPF 6/ethylene carbonate-diethyl carbonate (EC-DEC). With these polymer electrolytes, rechargeable lithium batteries composed of carbon anode and LiCoO 2 cathode have acceptable cycleability and a good rate capability.

Cheng, C. L.; Wan, C. C.; Wang, Y. Y.

364

Microstructure and selected properties of hot-work tool steel with PVD coatings after laser surface treatment  

NASA Astrophysics Data System (ADS)

The paper presents the effect of HPD laser treatment on the microstructure and selected properties of the PVD CrN, (Ti,Al) and Ti(C,N) coatings deposited onto hot-work tool steel substrates. The microstructure and surface topography of the investigated samples are characteristic of the diversified morphology connected with the applied laser beam power. Employment of laser beam at 0.7 kW power to the laser treatment of samples with Ti(C,N) coatings causes clear coating adhesion growth because of the diffusive processes induced by heat release. Because of the higher value of the (Ti,Al)N absorption coefficient one can state that the observed substrate materials change and finally coatings destruction in case of those samples is the most noticeable. The moderate effect of the laser beam treatment of the hot-work tool steel with the PVD coating was observed for CrN coatings. However, for laser beam power above 0.5 kW differences in the thermal expansion coefficients of the substrate materials and coatings generate coating crackings.

Adamiak, Marcin; Dobrza?ski, Leszek A.

2008-05-01

365

Development and evaluation of two PVD-coated ?-titanium orthodontic archwires for fluoride-induced corrosion protection.  

PubMed

The present research was aimed at developing surface coatings on ? titanium orthodontic archwires capable of protection against fluoride-induced corrosion. Cathodic arc physical vapor deposition PVD (CA-PVD) and magnetron sputtering were utilized to deposit thin films of titanium aluminium nitride (TiAlN) and tungsten carbide/carbon (WC/C) coatings on ? titanium orthodontic archwires. Uncoated and coated specimens were immersed in a high fluoride ion concentration mouth rinse, following a specially designed cycle simulating daily use. All specimens thus obtained were subjected to critical evaluation of parameters such as electrochemical corrosion behaviour, surface analysis, mechanical testing, microstructure, element release, and toxicology. The results confirm previous research that ? titanium archwires undergo a degradation process when in contact with fluoride mouth rinses. The study confirmed the superior nature of the TiAlN coating, evident as many fewer changes in properties after fluoride treatment when compared with the WC/C coating. Thus, coating with TiAlN is recommended in order to reduce the corrosive effects of fluorides on ? titanium orthodontic archwires. PMID:21111072

Krishnan, Vinod; Krishnan, Anand; Remya, R; Ravikumar, K K; Nair, S Asha; Shibli, S M A; Varma, H K; Sukumaran, K; Kumar, K Jyothindra

2011-04-01

366

Comparative study of deposition of thin films by laser-induced PVD with femtosecond and nanosecond laser pulses  

NASA Astrophysics Data System (ADS)

The influence of temporal pulse length on laser induced PVD of diamond-like carbon (DLC) as well as Si and Cu films is investigated, using 30 ns and 500 fs UV laser pulses of 248 nm. For the case of the DLC films the laser generated plasma is analyzed by time of flight (TOF) and also by optical emission spectroscopy. The TOF measurements of ablated carbon particles exhibit striking differences between nanosecond and femtosecond laser irradiation. In the case of 30 ns ablation, cluster formation is quite evident in the TOF mass spectra, which coincides with the observation of micron-sized particulates on the deposited DLC films. No evidence for cluster formation is found in the TOF spectra obtained from the femtosecond plasma. The corresponding optical emission spectra indicate a high contribution of C+, rather than C2, and larger molecules in the nanosecond case. In addition, much higher kinetic particle energies (in the keV range) have been measured, which are known to be favorable with respect to DLC film formation. Consequently, high optical quality DLC films without particulates can be grown by femtosecond laser induced PVD. The differences of the two pulse durations are also discussed with respect to ablation characteristics, plume formation, and deposition rates.

Mueller, F.; Mann, Klaus R.; Simon, Peter; Bernstein, Jeffrey S.; Zaal, Gerard J.

1993-04-01

367

Fe/Au Multilayers: Structure and Magnetoresistance  

SciTech Connect

We have measured the magnetoresistance (MR) in two sets of Fe/Au multilayers, with varying (1) Fe layer thickness, t{sub Fe} = 3-10 nm, and (2) Au layer thickness t{sub Au} = 5-15 nm, grown on Si substrates by sputtering. The multilayer interface structure and magnetic properties were studied by polarized neutron reflectometry (PNR). The study was undertaken to understand the correlation between structure of these multilayers and their magneto-transport properties.

Singh, Surendra; Basu, Saibal; Bhattacharya, D. [Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Prajapat, C. L. [Technical Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Gupta, M. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 (India)

2011-07-15

368

Multi-layer seal for electrochemical devices  

DOEpatents

Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

2010-09-14

369

Multi-layer seal for electrochemical devices  

DOEpatents

Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

2010-11-16

370

Repair of high performance multilayer coatings  

SciTech Connect

Fabrication and environmental damage issues may require that the multilayer x-ray reflection coatings used in soft x-ray projection lithography be replaced or repaired. Two repair strategies were investigated. The first was to overcoat defective multilayers with a new multilayer. The feasibility of this approach was demonstrated by depositing high reflectivity (61% at 130 {Angstrom}) molybdenum silicon (Mo/Si) multilayers onto fused silica figured optics that had already been coated with a Mo/Si multilayer. Because some types of damage mechanisms and fabrication errors are not repairable by this method, a second method of repair was investigated. The multilayer was stripped from the optical substrate by etching a release layer which was deposited onto the substrate beneath the multilayer. The release layer consisted of a 1000 {Angstrom} aluminum film deposited by ion beam sputtering or by electron beam evaporation, with a 300 {Angstrom} SiO{sub 2} protective overcoat. The substrates were superpolished zerodur optical flats. The normal incidence x-ray reflectivity of multilayers deposited on these aluminized substrates was degraded, presumably due to the roughness of the aluminum films. Multilayers, and the underlying release layers, have been removed without damaging the substrates.

Gaines, D.P. [Brigham Young Univ., Provo, UT (United States). Dept. of Physics and Astronomy; Ceglio, N.M. [Lawrence Livermore National Lab., CA (United States); Vernon, S.P. [Vernon Applied Physics, Torrance, CA (United States); Krumrey, M.; Mueller, P. [Physikalisch-Technische Bundesanstalt, Berlin (Germany). VUV Radiometric Lab.

1991-07-01

371

Nanocomposite metal amorphous-carbon thin films deposited by hybrid PVD and PECVD technique.  

PubMed

Carbon based films can combine the properties of solid lubricating graphite structure and hard diamond crystal structure, i.e., high hardness, chemical inertness, high thermal conductivity and optical transparency without the crystalline structure of diamond. Issues of fundamental importance associated with nanocarbon coatings are reducing stress, improving adhesion and compatibility with substrates. In this work new nanocomposite coatings with improved toughness based in nanocrystalline phases of metals and ceramics embedded in amorphous carbon matrix are being developed within the frame of a research project: nc-MeNxCy/a-C(Me) with Me = Mo, Si, Al, Ti, etc. Carbide forming metal/carbon (Me/C) composite films with Me = Mo, W or Ti possess appropriate properties to overcome the limitation of pure DLC films. These novel coating architectures will be adopted with the objective to decrease residual stress, improve adherence and fracture toughness, obtain low friction coefficient and high wear-resistance. Nanocomposite DLC's films were deposited by hybrid technique using a PVD-Physically Vapor Deposition (magnetron sputtering) and Plasma Enhanced Chemical Vapor Deposition (PECVD), by the use of CH4 gas. The parameters varied were: deposition time, substrate temperature (180 degrees C) and dopant (Si + Mo) of the amorphous carbon matrix. All the depositions were made on silicon wafers and steel substrates precoated with a silicon inter-layer. The characterisation of the film's physico-mechanical properties will be presented in order to understand the influence of the deposition parameters and metal content used within the a-C matrix in the thin film properties. Film microstructure and film hybridization state was characterized by Raman Spectroscopy. In order to characterize morphology SEM and AFM will be used. Film composition was measured by Energy-Dispersive X-ray analysis (EDS) and by X-ray photoelectron spectroscopy (XPS). The contact angle for the produced DLC's on silicon substrates were also measured. Thin film adherence was studied by micro-scratch test. Residual stresses in the produced coatings will be analysed by bending technique. PMID:19916409

Teixeira, V; Soares, P; Martins, A J; Carneiro, J; Cerqueira, F

2009-07-01

372

Reducing virulence of the human pathogen Burkholderia by altering the substrate specificity of the quorum-quenching acylase PvdQ.  

PubMed

The use of enzymes to interfere with quorum sensing represents an attractive strategy to fight bacterial infections. We used PvdQ, an effective quorum-quenching enzyme from Pseudomonas aeruginosa, as a template to generate an acylase able to effectively hydrolyze C8-HSL, the major communication molecule produced by the Burkholderia species. We discovered that the combination of two single mutations leading to variant PvdQ(L?146W,F?24Y) conferred high activity toward C8-HSL. Exogenous addition of PvdQ(L?146W,F?24Y) dramatically decreased the amount of C8-HSL present in Burkholderia cenocepacia cultures and inhibited a quorum sensing-associated phenotype. The efficacy of this PvdQ variant to combat infections in vivo was further confirmed by its ability to rescue Galleria mellonella larvae upon infection, demonstrating its potential as an effective agent toward Burkholderia infections. Kinetic analysis of the enzymatic activities toward 3-oxo-C12-L-HSL and C8-L-HSL corroborated a substrate switch. This work demonstrates the effectiveness of quorum-quenching acylases as potential novel antimicrobial drugs. In addition, we demonstrate that their substrate range can be easily switched, thereby paving the way to selectively target only specific bacterial species inside a complex microbial community. PMID:24474783

Koch, Gudrun; Nadal-Jimenez, Pol; Reis, Carlos R; Muntendam, Remco; Bokhove, Marcel; Melillo, Elena; Dijkstra, Bauke W; Cool, Robbert H; Quax, Wim J

2014-01-28

373

Effect of PVD films wet micro-blasting by various Al 2O 3 grain sizes on the wear behaviour of coated tools  

Microsoft Academic Search

Micro-blasting on PVD films has been documented, among others, as an efficient method for inducing compressive stresses, thus for increasing the coating hardness and potentially tool life of coated tools. Since contradictory results have been registered concerning the efficiency of wet micro-blasting on coated tools for improving the wear behaviour, the paper aims at explaining how this process can be

K.-D. Bouzakis; E. Bouzakis; G. Skordaris; S. Makrimallakis; A. Tsouknidas; G. Katirtzoglou; S. Gerardis

2011-01-01

374

Determination of mechanical properties of electron beam-physical vapor deposition-thermal barrier coatings (EB-PVD-TBCs) by means of nanoindentation and impact testing  

Microsoft Academic Search

EB-PVD-zirconia coatings are well known as thermal barrier coating materials for gas turbine applications. Using these materials, the gas turbine can work at higher temperatures, and thus the turbine efficiency increases. Due to the fact that not only the turbine efficiency, but also its reliability is a very important issue, prediction of the lifetime of thermal barrier coatings by assessment

K.-D Bouzakis; A Lontos; N Michailidis; O Knotek; E Lugscheider; K Bobzin; A Etzkorn

2003-01-01

375

Testing method to assess lifetime of EB-PVD thermal barrier coatings on tubular specimens in static and cyclic oxidation tests  

Microsoft Academic Search

A testing methodology is presented to assess the delamination failure of an yttria stabilized zirconia electron beam physical vapor deposited (EB-PVD) top-coat as studied for tubular specimens applying short thermal cycles with high heating and cooling rates as well as for oxidation tests at constant temperature. The influence of maximum temperature and specimen diameter were investigated. Higher maximum temperatures as

R. W. Steinbrech; V. Postolenko; J. Mönch; J. Malzbender; L. Singheiser

2011-01-01

376

Comparison of the damping and stiffness properties of 8wt% yttria stabilized zirconia ceramic coating deposited by the APS and EB-PVD techniques  

Microsoft Academic Search

Recent research into the use of thermal barrier coatings has shown that they can provide sufficient additional damping, reducing vibration levels and significantly extending the life of the coated component. Various deposition techniques may be employed to apply ceramic coatings with Air Plasma Spraying (APS) and Electron Beam - Physical Vapour Deposition (EB-PVD) being the most widely used. However, one

N. Tassini; K. Lambrinou; I. Mircea; S. Patsias; O. Van der Biest; R. Stanway

2005-01-01

377

Nanoscale Thermal Mapping of VO2  

NASA Astrophysics Data System (ADS)

We present a method for nanoscale thermal imaging of insulating thin films. We image the local temperature of the metal-insulator transition in a VO2 film, and investigate the role of Joule heating in two-terminal geometry. By sweeping the voltage applied to a conducting atomic force microscope tip in contact mode, we locally trigger and detect the transition to the metallic phase. By fitting the Poole-Frenkel conduction regime immediately preceding the transition, we extract the local temperature. Finally, we find grains displaying two electronic transitions, consistent with a locally stable intermediate insulating phase.[4pt] We acknowledge financial support from Harvard's Nanoscale Science and Engineering Center, funded by NSF grant PHY 01-17795 and the Sloan Fellowship. Adam Pivonka acknowledges the support of the New York Community Trust--George Merck Fund. Magdalena Huefner acknowledges the support of the Deutsche Forschungsgemeinschaft (HU 1960/11).

Pivonka, Adam; Huefner, Magdalena; Ko, Changhyun; Frenzel, Alex; O'Connor, Kevin; Ramanathan, Shriram; Hudson, Eric; Hoffman, Jennifer

2013-03-01

378

Nano-scale chemical and biological sensors  

NASA Astrophysics Data System (ADS)

Nano-engineered devices with potential for trace level detection of chemical or biological species are investigated. The sensor system is a ChemFET device based on micro- and nano-scale silicon wires. The sensor response to changes in pH reveals a significantly higher sensitivity of nano-scale devices compared to micro-scale devices. By immobilizing DNA probe molecules on the silicon wire surface, the ChemFET devices are rendered specific to this DNA sequence. Differential measurements minimize the effects of non-specific binding. At a concentration of CDNA=10?M, two different single stranded 24-base DNA oligonucleotides have been clearly distinguished in the sensor response. DNA hybridization on the silicon wire surface is further corroborated by fluorescence spectroscopy and analysis of characteristic time constants in the sensors response.

Moller, Sven; Hinch, Garry D.; Duda, Kenneth J.; Kornilovitch, Pavel; Peters, Kevin F.; Ward, Kenneth; Wei, Qingqiao; Yang, Xioafeng

2005-11-01

379

Twinnability of hcp metals at the nanoscale  

NASA Astrophysics Data System (ADS)

Twinning is generally considered to be the primary deformation mechanism for hexagonal close-packed (hcp) metals due to their limited slip systems. Recent microcompression experiments point to strong size effects indicating that pyramidal slips can dominate in deformation under compression. We present analysis on the twinnability of an ideal hcp single crystal at the nanoscale. A criterion for deformation twinning is derived by considering the elastic lattice-rotation strain, and the result tested against molecular dynamics simulations of magnesium and titanium single crystals. We find ?c + a? pyramidal slip dominates the compression deformation at the nanoscale, which is consistent with experimental observations on microcompression. This analysis gives an interpretation of size effects in deformation twinning, at the same time it provides an explanation for the so-called strength differential effect.

Guo, Ya-Fang; Xu, Shuang; Tang, Xiao-Zhi; Wang, Yue-Sheng; Yip, Sidney

2014-06-01

380

Trapping atoms using nanoscale quantum vacuum forces  

PubMed Central

Quantum vacuum forces dictate the interaction between individual atoms and dielectric surfaces at nanoscale distances. For example, their large strengths typically overwhelm externally applied forces, which makes it challenging to controllably interface cold atoms with nearby nanophotonic systems. Here we theoretically show that it is possible to tailor the vacuum forces themselves to provide strong trapping potentials. Our proposed trapping scheme takes advantage of the attractive ground-state potential and adiabatic dressing with an excited state whose potential is engineered to be resonantly enhanced and repulsive. This procedure yields a strong metastable trap, with the fraction of excited-state population scaling inversely with the quality factor of the resonance of the dielectric structure. We analyse realistic limitations to the trap lifetime and discuss possible applications that might emerge from the large trap depths and nanoscale confinement.

Chang, D. E.; Sinha, K.; Taylor, J. M.; Kimble, H. J.

2014-01-01

381

CMOS compatible nanoscale nonvolatile resistance switching memory.  

PubMed

We report studies on a nanoscale resistance switching memory structure based on planar silicon that is fully compatible with CMOS technology in terms of both materials and processing techniques employed. These two-terminal resistance switching devices show excellent scaling potential well beyond 10 Gb/cm2 and exhibit high yield (99%), fast programming speed (5 ns), high on/off ratio (10(3)), long endurance (10(6)), retention time (5 months), and multibit capability. These key performance metrics compare favorably with other emerging nonvolatile memory techniques. Furthermore, both diode-like (rectifying) and resistor-like (nonrectifying) behaviors can be obtained in the device switching characteristics in a controlled fashion. These results suggest that the CMOS compatible, nanoscale Si-based resistance switching devices may be well suited for ultrahigh-density memory applications. PMID:18217785

Jo, Sung Hyun; Lu, Wei

2008-02-01

382

Nanoscale Hydrophobic Interaction and Nanobubble Nucleation  

Microsoft Academic Search

We report large-scale atomistic simulation of midrange nanoscale hydrophobic interaction, manifested by the nucleation of nanobubble between nanometer-sized hydrophobes at constrained equilibrium. When the length scale of the hydrophobes is greater than 2nm, the nanobubble formation shows hysteresis behavior resembling the first-order transition. Calculation of the potential of mean force versus interhydrophobe distance provides a quantitative measure of the strength

T. Koishi; S. Yoo; K. Yasuoka; X. C. Zeng; T. Narumi; R. Susukita; A. Kawai; H. Furusawa; A. Suenaga; N. Okimoto; N. Futatsugi; T. Ebisuzaki

2004-01-01

383

Nanoscale structures and mechanics of barnacle cement  

Microsoft Academic Search

Polymerized barnacle glue was studied by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and chemical staining. Nanoscale structures exhibiting rod-shaped, globular and irregularly-shaped morphologies were observed in the bulk cement of the barnacle Amphibalanus amphitrite (=Balanus amphitrite) by AFM. SEM coupled with energy dispersive X-ray (EDX) provided chemical composition information, making evident the organic

Ruby May A. Sullan; Nikhil Gunari; Adrienne E. Tanur; Yuri Chan; Gary H. Dickinson; Beatriz Orihuela; Dan Rittschof; Gilbert C. Walker

2009-01-01

384

Biomolecules–Nanoparticles: Interaction in Nanoscale  

Microsoft Academic Search

\\u000a Even though the production of nanoparticles of silver and gold dates back many centuries, characterization and manipulation\\u000a at nanoscale has initiated a new era for nanotechnology. Spreading its wings beyond physics and materials science, its scope\\u000a of application in molecular biology, biochemistry, and medicine is only recently being appreciated. This necessitated a need\\u000a for the interaction between nanoparticles and biomolecules.

N. Vigneshwaran; Prateek Jain

385

Nanoscale oxidation of silicon microring resonators  

Microsoft Academic Search

* Email: smookherjea@ucsd.edu Abstract: The resonance frequency of a silicon microring was permanently blue-shifted with 1.2 GHz resolution over more than 350 GHz, a full free-spectral-range, by electrochemically changing the waveguide core (silicon) to the cladding (silicon dioxide) material. ?2011 Optical Society of America Silicon microring devices are sensitively affected by nanoscale disorder, e.g., few nanometer variations in the width

Yiran Shen; Shayan Mookherjea

2011-01-01

386

Nanoscale molecularly imprinted polymers and method thereof  

DOEpatents

Nanoscale molecularly imprinted polymers (MIP) having polymer features wherein the size, shape and position are predetermined can be fabricated using an xy piezo stage mounted on an inverted microscope and a laser. Using an AMF controller, a solution containing polymer precursors and a photo initiator are positioned on the xy piezo and hit with a laser beam. The thickness of the polymeric features can be varied from a few nanometers to over a micron.

Hart, Bradley R. (Brentwood, CA) [Brentwood, CA; Talley, Chad E. (Brentwood, CA) [Brentwood, CA

2008-06-10

387

Porous PVdF-HFP/P123 electrolyte membrane containing flexible quasi-solid-state dye-sensitized solar cells produced by the compression method  

NASA Astrophysics Data System (ADS)

Flexible quasi-solid-state dye-sensitized solar cells (DSSCs) with porous poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP)/polyethylene oxide-co-polypropylene oxide-co-polyethylene oxide (P123) electrolyte membranes were fabricated and their photocurrent-voltage (I-V) characteristics are studied. Flexible TiO2 photoelectrodes were prepared using the compression method and porous PVdF-HFP/P123 membranes, by the nonsolvent-induced phase inversion technique. To activate the electrolyte membrane, the membrane was immersed in liquid-state electrolyte. Increased compression pressure improved the interconnection between TiO2 nanoparticles, enhancing the photovoltaic performances of the flexible liquid-state DSSCs to a maximum of 3.92% efficiency. Meanwhile, the overall pore structure of the PVdF-HFP/P123 membranes was controlled by varying the blend ratio of P123 to PVdF-HFP. Membranes higher in P123 content gave larger pores and pore volume, increasing the electrolyte uptake of the porous membrane, and thus the ionic conductivity of the electrolyte membrane as well. The photovoltaic characteristics of the flexible quasi-solid-state DSSCs containing a porous PVdF-HFP/P123 electrolyte membrane showed a maximum at 50 wt% P123 content, which gave a short-circuit current density (Jsc) value of 7.28 mA/cm2, an open-circuit voltage (Voc) of 0.67 V, a fill factor (FF) of 0.61 and an energy conversion efficiency (?) of 2.98%. Furthermore, the device designed in this study showed good durability compared to those based on liquid-state electrolyte.

Kim, Jae Hong; Jung, Hee Suk; Park, Chung Hee; Kang, Tae Jin

2014-01-01

388

Kinetic mechanism of ornithine hydroxylase (PvdA) from Pseudomonas aeruginosa: substrate triggering of O2 addition but not flavin reduction†  

PubMed Central

PvdA catalyzes the hydroxylation of the sidechain primary amine of ornithine in the initial step of the biosynthesis of the Pseudomonas aeruginosa siderophore pyoverdin. The reaction requires FAD, NADPH, and O2. PvdA uses the same co-substrates as several flavin-dependent hydroxylases that differ one from another in the kinetic mechanisms of their oxidative and reductive half-reactions. Therefore, the mechanism of PvdA was determined by absorption stopped-flow experiments. By contrast to some flavin-dependent hydroxylases (notably, p-hydroxybenzoate hydroxylase), binding of the hydroxylation target is not required to trigger reduction of the flavin by NADPH: the reductive half-reaction is equally facile in the presence and absence of ornithine. Reaction of O2 with FADH2 in the oxidative half-reaction is accelerated by ornithine 80-fold, providing a mechanism by which PvdA can ensure coupling of NADPH and ornithine oxidation. In the presence of ornithine, the expected C(4a)-hydroperoxyflavin intermediate with 390-nm absorption accumulates and decays to the C(4a)-hydroxyflavin in a kinetically competent fashion. The slower oxidative half-reaction that occurs in the absence of ornithine involves accumulation of an oxygenated flavin species and two subsequent states that are tentatively assigned as C(4a)-peroxy- and -hydroperoxyflavin intermediates and the oxidized flavin. The enzyme generates stoichiometric hydrogen peroxide in lieu of hydroxyornithine. The data suggest that PvdA employs a kinetic mechanism that is a hybrid of those previously documented for other flavin-dependent hydroxylases.

Meneely, Kathleen M.; Barr, Eric W.; Bollinger, J. Martin; Lamb, Audrey L.

2009-01-01

389

Electronic structure of multilayer graphene  

NASA Astrophysics Data System (ADS)

The single-particle low-energy Hamiltonian of bilayer graphene describes chiral quasiparticles with a dominantly parabolic dispersion exhibiting Berry phase 2?. This chiral Hamiltonian produces a doubly-degenerate zero-energy Landau level incorporating two different orbital states with the same energy. Taking into account spin and valley degeneracies, the zero-energy Landau level in a bilayer is eightfold degenerate, as compared to the fourfold degeneracy of other bilayer states and the fourfold degeneracy of all levels in a monolayer. Such levels can be split by interlayer asymmetry, due to the presence of an external gate or doping, or by interaction effects. This talk will describe the electronic behavior of multilayer graphene, focusing on three, four and five layers. The goal will be to identify features that are distinct from those observed in monolayers and bilayers, and to highlight effects - such as level splitting and crossing - that can be explained either within the single-particle picture or that require an understanding of electronic interactions. For example, the low-energy Hamiltonian of ABA-stacked multilayer graphene may be partially diagonalized into an approximate block-diagonal form, with each diagonal block contributing parabolic bands except for an additional block describing Dirac-like bands with a linear dispersion in a multilayer with an odd number of layers. By taking into account the symmetry of the crystal structure, it is possible to fully include the band parameters and to analyze their effect on the block-diagonal Hamiltonian. Next-nearest-layer couplings are shown to be particularly important in determining the low-energy spectrum and the phase diagram of the quantum Hall conductivity by causing energy shifts, level anti-crossings, and valley splitting of the low-lying Landau levels. [4pt] This work was done in collaboration with Mikito Koshino of the Department of Physics, Tohoku University, Sendai 980-8578, Japan.

McCann, Edward

2012-02-01

390

Applications of VUV Multilayer Optics in Astronomy  

Microsoft Academic Search

A relatively new technology for fabricating multilayer optics that operate in the vacuum ultraviolet (VUV) at near normal incidence is finding broad application in both solar and galactic astronomy. These optics provide a number of advantages for use in astronomical instruments that make them highly complementary to traditional grazing incidence VUV optics. Five separate multilayer telescopes have already been used

R C Catura

1990-01-01

391

Thermal stability of Mo/Si multilayers.  

National Technical Information Service (NTIS)

The thermal stability of Mo/Si multilayers for x-ray mirror applications was investigated by annealing studies at relatively low temperatures for various times. The as-deposited and annealed multilayers were examined using conventional small and large ang...

R. S. Rosen D. G. Stearns M. A. Viliardos M. E. Kassner S. P. Vernon

1991-01-01

392

Laser bonding of multilayer polymer microfluidic chips  

Microsoft Academic Search

Polymer microfluidic chips have stimulated great instrests in the field of biochemical and medical analysis due to their low prices, easy fabrication and biocompatibility. Recently multilayer microfluidic chips have been fabricated by adhesive bonding to form 3-D multilayer laminate. However adhesive bonding may introduce pollution as well as complexity in coating. A bonding system with compact diode laser is introduced

Jianjun Lai; Hui Yuan; Xin-Jian Yi; Sheng Liu

2005-01-01

393

Scaling properties of multilayer fractal structures  

Microsoft Academic Search

Multilayer fractal structures, being a subclass of nonperiodic yet deterministic media are studied in relation to the problem of classical wave propagation. A general case of fractal multilayers is considered. Numerical calculations reveal that the geometry and optical spectra of such structures are directly connected. Namely, it has been found that structures and spectra exhibit exactly the same scaling relations,

S. V. Zhurkovsky; Andrei V. Lavrinenko; Sergey V. Gaponenko

2002-01-01

394

Multilayer Perceptrons to Approximate Quaternion Valued Functions  

Microsoft Academic Search

In this paper a new type of multilayer feedforward neural network is introduced. Such a structure, called hypercomplex multilayer perceptron (HMLP), is developed in quaternion algebra and allows quaternionic input and output signals to be dealt with, requiring a lower number of neurons than the real MLP, thus providing a reduced computational complexity. The structure introduced represents a generalization of

Paolo Arena; Luigi Fortuna; Giovanni Muscato; Maria Gabriella Xibilia

1997-01-01

395

Magnetoresistive multilayers deposited on the AAO membranes  

Microsoft Academic Search

Silicon and GaAs wafers are the most commonly used substrates for deposition of giant magnetoresistive (GMR) multilayers. We explored a new type of a substrate, prepared electrochemically by anodization of aluminum sheets, for deposition of GMR multilayers. The surface of this AAO substrate consists of nanosized hemispheres organized in a regular hexagonal array. The current applied along the substrate surface

Leszek M. Malkinski; Athanasios Chalastaras; Andriy Vovk; Jin-Seung Jung; Eun-Mee Kim; Jong-Ho Jun; Carl A. Ventrice Jr

2005-01-01

396

Multi-Layer E-Textile Circuits  

NASA Technical Reports Server (NTRS)

Stitched e-textile circuits facilitate wearable, flexible, comfortable wearable technology. However, while stitched methods of e-textile circuits are common, multi-layer circuit creation remains a challenge. Here, we present methods of stitched multi-layer circuit creation using accessible tools and techniques.

Dunne, Lucy E.; Bibeau, Kaila; Mulligan, Lucie; Frith, Ashton; Simon, Cory

2012-01-01

397

Coherent multilayer crystals and method of making  

DOEpatents

A new material is described consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Schuller, I.K.; Falco, C.M.

1980-10-30

398

Method of making coherent multilayer crystals  

DOEpatents

A new material consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 .ANG. to 2500 .ANG.. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Woodridge, IL)

1984-01-01

399

Dynamic materials from microgel multilayers.  

PubMed

Multilayer coatings made from hydrogel microparticles (microgels) are conceptually very simple materials: thin films composed of microgel building blocks held together by polyelectrolyte "glue". However, the apparent simplicity of their fabrication and structure belies extremely complex properties, including those of "dynamic" coatings that display rapid self-healing behavior in the presence of solvent. This contribution covers our work with these materials and highlights some of the key findings regarding damage mechanisms, healing processes, film structure/composition, and how the variation of fabrication parameters can impact self-healing behavior. PMID:24295444

Spears, Mark William; Herman, Emily S; Gaulding, Jeffrey C; Lyon, L Andrew

2014-06-10

400

Bioinspired design of dental multilayers.  

PubMed

This paper considers the use of bioinspired functionally graded structures in the design of dental multi-layers that are more resistant to sub-surface crack nucleation. Unlike existing dental crown restorations that give rise to high stress concentration, the functionally graded layers (between crown materials and the joins that attach them to dentin) are shown to promote significant reductions in stress and improvements in the critical crack size. Special inspiration is drawn from the low stress concentrations associated with the graded distributions in the dentin-enamel-junction (DEJ). The implications of such functionally graded structures are also discussed for the design of dental restorations. PMID:17200814

Huang, M; Wang, R; Thompson, V; Rekow, D; Soboyejo, W O

2007-01-01

401

Methods of fabricating nanoscale-to-microscale structures  

US Patent & Trademark Office Database

Methods for the production of shaped nanoscale-to-microscale structures, wherein a nanoscale-to-microscale template is provided having an original chemical composition and an original shape, and the nanoscale-to-microscale template subjected to a chemical reaction, so as to partially or completely convert the nanoscale-to-microscale template into the shaped nanoscale-to-microscale structure having a chemical composition different than the original chemical composition and having substantially the same shape as the original shape, being a scaled version of the original shape. The shaped nanoscale-to-microscale structure formed comprises an element (such as silicon), a metallic alloy (such as a silicon alloy), or a non-oxide compound (such as silicon carbide or silicon nitride).

2009-11-10

402

Bumpy, Sticky, and Shaky: Nanoscale Science and the Curriculum  

NSDL National Science Digital Library

Nanoscience, or the study of the world at the size of a billionth of a meter, has the potential to help students see how all of the sciences are related. Behavior of materials at the nanoscale differs from materials at the macroscale. This article introduces three nanoscale properties and how they relate to various science domains. Three activities following an adapted learning cycle model are suggested for student exploration of three properties of the nanoscale: bumpy, sticky, and shaky.

Taylor, Amy; Jones, Gail; Pearl, Thomas P.

2008-03-01

403

Treatment of chlorinated organic contaminants with nanoscale bimetallic particles  

Microsoft Academic Search

Nanoscale bimetallic particles (Pd\\/Fe, Pd\\/Zn, Pt\\/Fe, Ni\\/Fe) have been synthesized in the laboratory for treatment of chlorinated organic pollutants. Specific surface areas of the nanoscale particles are tens of times larger than those of commercially available microscale metal particles. Rapid and complete dechlorination of several chlorinated organic solvents and chlorinated aromatic compounds was achieved by using the nanoscale bimetallic particles.

Wei-xian Zhang; Chuan-Bao Wang; Hsing-Lung Lien

1998-01-01

404

Degradation of chlorinated phenols by nanoscale zero-valent iron  

Microsoft Academic Search

Chlorophenols (CPs), as important contaminants in groundwater, are toxic and difficult to biodegrade. Recently nanoscale zero-valent\\u000a iron received a great deal of attention because of its excellent performance in treating recalcitrant compounds. In this study,\\u000a nanoscale zero-valent iron particles were prepared using chemical reduction, and the reductive transformations of three kinds\\u000a of chlorinated phenols (2-CP, 3-CP, and 4-CP) by nanoscale

Rong Cheng; Jianlong Wang; Weixian Zhang

2008-01-01

405

Nanoscale mechanics of ductile interphases in solid solution directionally solidified eutectic composites  

NASA Astrophysics Data System (ADS)

Ceramic matrix composites are known for their low density, high strength and high stiffness, but lower fracture toughness compared to metal matrix composites. The addition of a reinforcing agent within the matrix can increase the toughness of the composite via many strain energy absorption mechanisms such as plastic deformation. This dissertation attempts to shed light on the competing deformation and fracture mechanisms in ductile/brittle nanoscale lamellar systems where the conventional deformation mechanisms may not apply. NixCo1-xO/ZrO2 Directionally Solidified Eutectic (DSE) composite series has been chosen as a model system for this study. In the first part of this dissertation, it is demonstrated that formation of a novel metal-ceramic multi-layered structure is feasible via reduction of NixCo1-xO/ZrO2 composite as a result of the interfaces forming an electrochemical cell in a reducing atmosphere at high temperatures. The second part of the thesis is dedicated in understanding the correlative deformation and fracture mechanisms in the reduced NixCo1-x O/ZrO2 model system with a nanoscale Ni(Co) confined interphase. These investigations were inspired by a novel observation that there is striking dissimilarity in the interfacial fracture behavior of the reduced Ni xCo1-xO/ZrO2 composite compared to that of the fully oxidized NixCo1-xO/ZrO2 system. A multitude of conventional and analytical electron microscopy techniques are utilized to investigate the role of the size scale, chemistry of this model system on the strain energy absorption upon deformation. FIB TEM lift-off technique is further employed to investigate the crack tip interactions with the nanoscale confined interphases in this model system. To study the role of size scale, the nanoscale deformation mechanism within the metallic interphase is investigated across 50-300 nm thickness range for the confined Ni(Co) interphase. The role of chemistry on the small scale deformation mechanisms in this model system is investigated by choosing two different compositions in the NixCo1-xO/ZrO2 composite series: CoO/ZrO 2 with x=0 and Ni0.5Co0.5O/ZrO2 with x=0.5. These investigations confirm that the metallic interphase, with the thickness of above 100 nm, contributes to strain energy absorption through plastic deformation. With decreasing the interphase size scale to values below 100 nm, the extent of plasticity is reduced within the metallic interphase.

Alem, Nasim

406

Nanoscale heat transfer--from computation to experiment.  

PubMed

Heat transfer can differ distinctly at the nanoscale from that at the macroscale. Recent advancement in computational and experimental techniques has enabled a large number of interesting observations and understanding of heat transfer processes at the nanoscale. In this review, we will first discuss recent advances in computational and experimental methods used in nanoscale thermal transport studies, followed by reviews of novel thermal transport phenomena at the nanoscale observed in both computational and experimental studies, and discussion on current understanding of these novel phenomena. Our perspectives on challenges and opportunities on computational and experimental methods are also presented. PMID:23361372

Luo, Tengfei; Chen, Gang

2013-03-14

407

Nanoscale Science and Engineering: A Priority Investment for NSF  

NSF Publications Database

... Synthesize Semiconductor Nanowires Nanoscale Polymer Yields Extremely Slick Coating Nanogeoscience ... at San Diego have developed a silicon polymer nanowire that can identify trace amounts of explosives ...

408

Impact on multilayered composite plates  

NASA Technical Reports Server (NTRS)

Stress wave propagation in a multilayer composite plate due to impact was examined by means of the anisotropic elasticity theory. The plate was modelled as a number of identical anisotropic layers and the approximate plate theory of Mindlin was then applied to each layer to obtain a set of difference-differential equations of motion. Dispersion relations for harmonic waves and correction factors were found. The governing equations were reduced to difference equations via integral transforms. With given impact boundary conditions these equations were solved for an arbitrary number of layers in the plate and the transient propagation of waves was calculated by means of a Fast Fourier Transform algorithm. The multilayered plate problem was extended to examine the effect of damping layers present between two elastic layers. A reduction of the interlaminar normal stress was significant when the thickness of damping layer was increased but the effect was mostly due to the softness of the damping layer. Finally, the problem of a composite plate with a crack on the interlaminar boundary was formulated.

Kim, B. S.; Moon, F. C.

1977-01-01

409

An investigation of PVdF/PVC-based blend electrolytes with EC/PC as plasticizers in lithium battery applications  

NASA Astrophysics Data System (ADS)

Solid polymer electrolytes (SPEs) composed of poly(vinylidene fluoride) (PVdF)-poly(vinyl chloride) (PVC) complexed with lithium perchlorate (LiClO 4) as salt and ethylene carbonate (EC)/propylene carbonate (PC) as plasticizers were prepared using solvent-casting technique, with different weight ratios of EC and PC. The amorphicity and complexation behavior of the polymer electrolytes were confirmed using X-ray diffraction (XRD) and FTIR studies. TG/DTA and scanning electron microscope (SEM) studies explained the thermal stability and surface morphology of electrolytes, respectively. The prepared thin films were subjected to AC impedance measurements as a function of temperature ranging from 302 to 373 K. The temperature-dependence conductivity of polymer films seems to obey VTF relation.

Rajendran, S.; Sivakumar, P.

2008-03-01

410

Dependence of microstructure and thermal conductivity of EB-PVD thermal barrier coatings on the substrate rotation speed  

NASA Astrophysics Data System (ADS)

EB-PVD TBCs were deposited at nearly the same process parameters but substrate rotation speed to investigate the effect of rotation adjustment on microstructure and thermal conductivity. The microstructure was checked by scanning electron microscopy (SEM) and the thermal conductivity was calculated on the basis of determination of thermal diffusivity by laser flash method. The results showed the stationary deposition formed most dense coating and increasing rotation speed resulted in wider columnar grains and enlarged shadowing effect which meant much more volume of pores. The density and thermal conductivity at room temperature both decreased with increasing rotation speed. The lowest experimental value, 1.37 W/mK, was obtained for a 171 ?m thick free-standing coating, when the rotation speed was 20 rpm in this study.

Liu, Liang; Zhang, Huafang; Lei, Xingeng; Zheng, Yufeng

411

Studies on the effect of dispersoid(ZrO2) in PVdF-co-HFP based gel polymer electrolytes  

NASA Astrophysics Data System (ADS)

Gel polymer electrolytes containing poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) / Lithium bis(trifluoromethane sulfon)imide (LiTFSI) / mixture of ethylene carbonate and propylene carbonate (EC+PC) with different concendration of ZrO2 has been prepared using the solution casting technique. The conductivity of the prepared electrolyte sample has been determined by AC impedance technique in the range 303-353K. The temperature dependent ionic conductivity plot seems to obey VTF relation. The maximum ionic conductivity value of 4.46 × 10-3S/cm has been obtained for PVdF-co-HFP(32%) - LiTFSI(8%) - EC+PC (60%) + ZrO2(6wt%) based polymer electrolyte. The surface morphology of the prepared electrolyte sample has been studied using SEM.

Sivakumar, M.; Subadevi, R.; Muthupradeepa, R.

2013-06-01

412

EDITORIAL: Mastering matter at the nanoscale Mastering matter at the nanoscale  

Microsoft Academic Search

In the early 1980s, the development of scanning probe techniques gave scientists a titillating view of surfaces with nanometre resolution, igniting activity in research at the nanoscale. Images at unprecedented resolution were unveiled with the aid of various types of nanosized tips, including the scanning tunnelling (Binnig G, Rohrer H, Gerber C and Weibel E 1982 Appl. Phys. Lett. 40

Alfred Forchel

2009-01-01

413

Dustiness of Fine and Nanoscale Powders  

PubMed Central

Dustiness may be defined as the propensity of a powder to form airborne dust by a prescribed mechanical stimulus; dustiness testing is typically intended to replicate mechanisms of dust generation encountered in workplaces. A novel dustiness testing device, developed for pharmaceutical application, was evaluated in the dustiness investigation of 27 fine and nanoscale powders. The device efficiently dispersed small (mg) quantities of a wide variety of fine and nanoscale powders, into a small sampling chamber. Measurements consisted of gravimetrically determined total and respirable dustiness. The following materials were studied: single and multiwalled carbon nanotubes, carbon nanofibers, and carbon blacks; fumed oxides of titanium, aluminum, silicon, and cerium; metallic nanoparticles (nickel, cobalt, manganese, and silver) silicon carbide, Arizona road dust; nanoclays; and lithium titanate. Both the total and respirable dustiness spanned two orders of magnitude (0.3–37.9% and 0.1–31.8% of the predispersed test powders, respectively). For many powders, a significant respirable dustiness was observed. For most powders studied, the respirable dustiness accounted for approximately one-third of the total dustiness. It is believed that this relationship holds for many fine and nanoscale test powders (i.e. those primarily selected for this study), but may not hold for coarse powders. Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size. For a subset of test powders, aerodynamic particle size distributions by number were measured (with an electrical low-pressure impactor and an aerodynamic particle sizer). Particle size modes ranged from approximately 300nm to several micrometers, but no modes below 100nm, were observed. It is therefore unlikely that these materials would exhibit a substantial sub-100nm particle contribution in a workplace.

Evans, Douglas E.; Baron, Paul A.

2013-01-01

414

Probing nanoscale deformations of a fluctuating interface  

NASA Astrophysics Data System (ADS)

We consider the contribution of thermal capillary waves to the interaction between a fluid-fluid interface and a nearby nanoparticle. Fluctuations are described thanks to an effective interaction potential which is derived using the renormalization group. The general theory is then applied to a spherical particle interacting with the interface through van der Waals forces. Surprisingly enough, we find that fluctuations contribute significantly to the deformation profile. Our study therefore reveals that thermal fluctuations cannot be ignored when probing nanoscale deformations of a soft interface.

Bickel, T.

2014-04-01

415

Long range interactions in nanoscale science  

NASA Astrophysics Data System (ADS)

Our understanding of the “long range” electrodynamic, electrostatic, and polar interactions that dominate the organization of small objects at separations beyond an interatomic bond length is reviewed. From this basic-forces perspective, a large number of systems are described from which one can learn about these organizing forces and how to modulate them. The many practical systems that harness these nanoscale forces are then surveyed. The survey reveals not only the promise of new devices and materials, but also the possibility of designing them more effectively.

French, Roger H.; Parsegian, V. Adrian; Podgornik, Rudolf; Rajter, Rick F.; Jagota, Anand; Luo, Jian; Asthagiri, Dilip; Chaudhury, Manoj K.; Chiang, Yet-Ming; Granick, Steve; Kalinin, Sergei; Kardar, Mehran; Kjellander, Roland; Langreth, David C.; Lewis, Jennifer; Lustig, Steve; Wesolowski, David; Wettlaufer, John S.; Ching, Wai-Yim; Finnis, Mike; Houlihan, Frank; von Lilienfeld, O. Anatole; van Oss, Carel Jan; Zemb, Thomas

2010-04-01

416

Space qualification of multilayered optics  

NASA Astrophysics Data System (ADS)

The feasibility for the ESA SOHO mission, of spectrally selected normal incidence telescopes in the XUV wavelength range is demonstrated in an evaluation of multilayered mirrors illuminated by the sun. Worst case solar vacuum tests of unprotected telescopes illuminated by a xenon arc lamp simulator indicate less than 10 percent decrease in reflectivity of the exposed section of the Hf/Si sample for the secondary mirrors. Primary mirror tests are currently being performed aboard the NASA Long Duration Exposure Facility. Results of protecting filter tests suggest a growth from 40-100 A in the thickness of the two aluminum oxide layers protecting the aluminum, in contradiction to previous findings (Hunter et al., 1973).

Delaboudiniere, J.-P.; Chauvineau, J.-P.; Marioge, J.-P.

417

Multilayer coatings on figured optics  

SciTech Connect

Soft X-Ray Projection Lithography (SXPL) will reqire uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f{sup {number_sign}}) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f{sup {number_sign}}3.4 and f{sup {number_sign}}6 optics 5 and 7.5 cm in diameter using planar DC magnetron sputtering. Measurements of the normal incidence reflectivity (NIR) of 63% at 13 nm uniform over the central 5 cm of the figured surface were obtained. Comparison of the measured values to model calculations of the wavelength dependent reflectivity indicate that the ML period is uniform to better than 0.04 nm over thiS region. 7 refs.

Vernon, S.P. [Vernon Applied Physics, Torrance, CA (United States); Stearns, D.G.; Rosen, R.S.; Ceglio, N.M.; Gaines, D.P. [Lawrence Livermore National Lab., CA (United States); Krumrey, M.; Mueller, P. [Physikalisch-Technische Bundesanstalt, Berlin (Germany). VUV Radiometric Lab.

1991-07-01

418

Multilayer coatings on figured optics  

NASA Astrophysics Data System (ADS)

Soft x-ray projection lithography (SXPL) requires uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f 3.4 and f 6 optics 5 and 7.5 cm in diameter using planar dc magnetron sputtering. Measurements of the normal incidence reflectivity (NIR) of 63% at 13 nm uniform over the central 5 cm of the figured surface were obtained. Comparison of the measured values to model calculations of the wavelength dependent reflectivity indicate that the ML period is uniform to better than 0.04 nm over this region.

Vernon, Stephen P.; Stearns, Daniel G.; Rosen, Robert S.; Ceglio, Natale M.; Gaines, David P.; Krumrey, Michael K.; Mueller, Peter

1992-01-01

419

Multilayer coatings on figured optics  

SciTech Connect

Soft X-Ray Projection Lithography (SXPL) will reqire uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f{sup {number sign}}) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f{sup {number sign}}3.4 and f{sup {number sign}}6 optics 5 and 7.5 cm in diameter using planar DC magnetron sputtering. Measurements of the normal incidence reflectivity (NIR) of 63% at 13 nm uniform over the central 5 cm of the figured surface were obtained. Comparison of the measured values to model calculations of the wavelength dependent reflectivity indicate that the ML period is uniform to better than 0.04 nm over thiS region. 7 refs.

Vernon, S.P. (Vernon Applied Physics, Torrance, CA (United States)); Stearns, D.G.; Rosen, R.S.; Ceglio, N.M.; Gaines, D.P. (Lawrence Livermore National Lab., CA (United States)); Krumrey, M.; Mueller, P. (Physikalisch-Technische Bundesanstalt, Berlin (Germany). VUV Radiometric Lab.)

1991-07-01

420

Highly Efficient Multilayer Thermoelectric Devices  

NASA Technical Reports Server (NTRS)

Multilayer thermoelectric devices now at the prototype stage of development exhibit a combination of desirable characteristics, including high figures of merit and high performance/cost ratios. These devices are capable of producing temperature differences of the order of 50 K in operation at or near room temperature. A solvent-free batch process for mass production of these state-of-the-art thermoelectric devices has also been developed. Like prior thermoelectric devices, the present ones have commercial potential mainly by virtue of their utility as means of controlled cooling (and/or, in some cases, heating) of sensors, integrated circuits, and temperature-critical components of scientific instruments. The advantages of thermoelectric devices for such uses include no need for circulating working fluids through or within the devices, generation of little if any noise, and high reliability. The disadvantages of prior thermoelectric devices include high power consumption and relatively low coefficients of performance. The present development program was undertaken in the hope of reducing the magnitudes of the aforementioned disadvantages and, especially, obtaining higher figures of merit for operation at and near room temperature. Accomplishments of the program thus far include development of an algorithm to estimate the heat extracted by, and the maximum temperature drop produced by, a thermoelectric device; solution of the problem of exchange of heat between a thermoelectric cooler and a water-cooled copper block; retrofitting of a vacuum chamber for depositing materials by sputtering; design of masks; and fabrication of multilayer thermoelectric devices of two different designs, denoted I and II. For both the I and II designs, the thicknesses of layers are of the order of nanometers. In devices of design I, nonconsecutive semiconductor layers are electrically connected in series. Devices of design II contain superlattices comprising alternating electron-acceptor (p)-doped and electron-donor (n)-doped, nanometer- thick semiconductor layers.

Boufelfel, Ali

2006-01-01

421

Magnesium-free self-assembly of multi-layer DNA objects  

PubMed Central

Molecular self-assembly with DNA offers a route for building user-defined nanoscale objects, but an apparent requirement for magnesium in solution has limited the range of conditions for which practical utility of such objects may be achieved. Here we report conditions for assembling templated multi-layer DNA objects in the presence of monovalent ions, showing that neither divalent cations in general or magnesium in particular are essential ingredients for the successful assembly of such objects. The percentage of DNA strands in an object that do not form thermally stable double-helical DNA domains (Tm>45?°C) with the template molecule correlated with the sodium requirements for obtaining folded objects. Minimizing the fraction of such weakly binding strands by rational design choices enhanced the yield of folding. The results support the view that DNA-based nanodevices may be designed and produced for a variety of target environments.

Martin, Thomas G.; Dietz, Hendrik

2012-01-01

422

Bumpy, Sticky, and Shaky: Nanoscale Science and the Curriculum  

ERIC Educational Resources Information Center

Nanoscience, or the study of the world at the size of a billionth of a meter, has the potential to help students see how all of the sciences are related. Behavior of materials at the nanoscale differs from materials at the macroscale. This article introduces three nanoscale properties and how they relate to various science domains. Three…

Taylor, Amy; Jones, Gail; Pearl, Thomas P.

2008-01-01

423

Essential physics of carrier transport in nanoscale MOSFETs  

Microsoft Academic Search

The device physics of nanoscale MOSFETs is explored by numerical simulations of a model transistor. The physics of charge control, source velocity saturation due to thermal injection, and scattering in ultrasmall devices are examined. The results show that the essential physics of nanoscale MOSFETs can be understood in terms of a conceptually simple scattering model

Mark Lundstrom; Zhibin Ren

2002-01-01

424

Method to determine thermal profiles of nanoscale circuitry  

DOEpatents

A platform that can measure the thermal profiles of devices with nanoscale resolution has been developed. The system measures the local temperature by using an array of nanoscale thermometers. This process can be observed in real time using a high resolution imagining technique such as electron microscopy. The platform can operate at extremely high temperatures.

Zettl, Alexander K; Begtrup, Gavi E

2013-04-30

425

A nanoscale probe for fluidic and ionic transport  

Microsoft Academic Search

Surface science and molecular biology are often concerned with systems governed by fluid dynamics at the nanoscale, where different physical behaviour is expected. With advances in nanofabrication techniques, the study of fluid dynamics around a nano-object or in a nano channel is now more accessible experimentally and has become an active field of research. However, developing nanoscale probes that can

Bertrand Bourlon; Joyce Wong; Csilla Mikó; László Forró; Marc Bockrath

2007-01-01

426

Recombinant protein-based nanoscale biomemory devices.  

PubMed

Biomolecular computing devices that are based on the properties of biomolecular activities offer a unique possibility for constructing new computing structures. A new concept of using various biomolecules has been proposed in order to develop a protein-based memory device that is capable of switching physical properties when electrical input signals are applied to perform memory switching. To clarify the proposed concept, redox protein is immobilized on Au nanoelectrodes to catalyze reversible reactions of redox-active molecules, which is controlled electrochemically and reversibly converted between its ON/OFF states. In this review, we summarize recent research towards developing nanoscale biomemory devices including design, synthesis, fabrication, and functionalization based on the proposed concept. At first we analyze the memory function properties of the proposed device at bulk material level and then explain the WORM (write-once-read-many times) nature of the device, later we extend the analysis to multi-bit and multi-level storage functions, and then we focus the developments in nanoscale biomemory devices based on the electron transport of redox molecules to the underlying Au patterned surface. The developed device operates at very low voltages and has good stability and excellent reversibility, proving to be a promising platform for future memory devices. PMID:24730273

Yagati, A K; Min, J; Choi, J W

2014-01-01

427

Constructal heat trees at micro and nanoscales  

NASA Astrophysics Data System (ADS)

We consider the problem of cooling a two-dimensional heat generating conducting volume with one heat sink, such that the smallest features of the internal structure are so small that the conventional description of conduction breaks down. The effective thermal conductivity exhibits the ``size effect,'' and is governed by the smallest structural dimension, which is comparable with the mean free path of the energy carriers. According to the constructal method, the development of the internal cooling structure proceeds from small to large, in steps of geometric optimization and assembly. This starts at the elemental level, where there is only one high-conductivity layer for collecting and evacuating the heat. The shape of the smallest volume can be optimized for minimal thermal resistance. Next, a first construct is formed by optimizing the number of assembled elements and the internal geometric features of the assembly. The method is repeated at the second construct level, where several first constructs are grouped so that their global thermal resistance is minimal. The construction reveals an internal multiscale structure shaped as a tree, where the spaces between the smallest branches are ruled by nanoscale heat transfer. It is shown that the transition from regions with nanoscale heat transfer to regions with conventional heat transfer is governed not only by the smallest dimensions, but also by heterogeneity (relative amounts of high- and low-conductivity materials).

Gosselin, Louis; Bejan, Adrian

2004-11-01

428

Can amorphization take place in nanoscale interconnects?  

PubMed

The trend of miniaturization has highlighted the problems of heat dissipation and electromigration in nanoelectronic device interconnects, but not amorphization. While amorphization is known to be a high pressure and/or temperature phenomenon, we argue that defect density is the key factor, while temperature and pressure are only the means. For nanoscale interconnects carrying modest current density, large vacancy concentrations may be generated without the necessity of high temperature or pressure due to the large fraction of grain boundaries and triple points. To investigate this hypothesis, we performed in situ transmission electron microscope (TEM) experiments on 200 nm thick (80 nm average grain size) aluminum specimens. Electron diffraction patterns indicate partial amorphization at modest current density of about 10(5) A cm(-2), which is too low to trigger electromigration. Since amorphization results in drastic decrease in mechanical ductility as well as electrical and thermal conductivity, further increase in current density to about 7 × 10(5) A cm(-2) resulted in brittle fracture failure. Our molecular dynamics (MD) simulations predict the formation of amorphous regions in response to large mechanical stresses (due to nanoscale grain size) and excess vacancies at the cathode side of the thin films. The findings of this study suggest that amorphization can precede electromigration and thereby play a vital role in the reliability of micro/nanoelectronic devices. PMID:22322399

Kumar, S; Joshi, K L; van Duin, A C T; Haque, M A

2012-03-01

429

Poroelasticity of Cartilage at the Nanoscale  

PubMed Central

Atomic-force-microscopy-based oscillatory loading was used in conjunction with finite element modeling to quantify and predict the frequency-dependent mechanical properties of the superficial zone of young bovine articular cartilage at deformation amplitudes, ?, of ?15 nm; i.e., at macromolecular length scales. Using a spherical probe tip (R ? 12.5 ?m), the magnitude of the dynamic complex indentation modulus, |E?|, and phase angle, ?, between the force and tip displacement sinusoids, were measured in the frequency range f ? 0.2–130 Hz at an offset indentation depth of ?0 ? 3 ?m. The experimentally measured |E?| and ? corresponded well with that predicted by a fibril-reinforced poroelastic model over a three-decade frequency range. The peak frequency of phase angle, fpeak, was observed to scale linearly with the inverse square of the contact distance between probe tip and cartilage, 1/d2, as predicted by linear poroelasticity theory. The dynamic mechanical properties were observed to be independent of the deformation amplitude in the range ? = 7–50 nm. Hence, these results suggest that poroelasticity was the dominant mechanism underlying the frequency-dependent mechanical behavior observed at these nanoscale deformations. These findings enable ongoing investigations of the nanoscale progression of matrix pathology in tissue-level disease.

Nia, Hadi Tavakoli; Han, Lin; Li, Yang; Ortiz, Christine; Grodzinsky, Alan

2011-01-01

430

Structure of nanoscale gas bubbles in metals  

NASA Astrophysics Data System (ADS)

A usual way to estimate the amount of gas in a bubble inside a metal is to assume thermodynamic equilibrium, i.e., the gas pressure P equals the capillarity force 2?/R, with ? the surface energy of the host material and R the bubble radius; under this condition there is no driving force for vacancies to be emitted or absorbed by the bubble. In contrast to the common assumption that pressure inside a gas or fluid bubble is constant, we show that at the nanoscale this picture is no longer valid. P and density can no longer be defined as global quantities determined by an equation of state (EOS), but they become functions of position because the bubble develops a core-shell structure. We focus on He in Fe and solve the problem using both continuum mechanics and empirical potentials to find a quantitative measure of this effect. We point to the need of redefining an EOS for nanoscale gas bubbles in metals, which can be obtained via an average pressure inside the bubble. The resulting EOS, which is now size dependent, gives pressures that differ by a factor of two or more from the original EOS for bubble diameters of 1 nm and below.

Caro, A.; Schwen, D.; Martinez, E.

2013-11-01

431

Nanoscale device modeling: the Green's function method  

NASA Astrophysics Data System (ADS)

The non-equilibrium Green's function (NEGF) formalism provides a sound conceptual basis for the devlopment of atomic-level quantum mechanical simulators that will be needed for nanoscale devices of the future. However, this formalism is based on concepts that are unfamiliar to most device physicists and chemists and as such remains relatively obscure. In this paper we try to achieve two objectives: (1) explain the central concepts that define the 'language' of quantum transport, and (2) illustrate the NEGF formalism with simple examples that interested readers can easily duplicate on their PCs. These examples all involve a short n + + - n + - n + + resistor whose physics is easily understood. However, the basic formulation is quite general and can even be applied to something as different as a nanotube or a molecular wire, once a suitable Hamiltonian has been identified. These examples also underscore the importance of performing self-consistent calculations that include the Poisson equation. The I- V characteristics of nanoscale structures is determined by an interesting interplay between twentieth century physics (quantum transport) and nineteenth century physics (electrostatics) and there is a tendency to emphasize one or the other depending on one's background. However, it is important to do justice to both aspects in order to derive real insights.

Datta, Supriyo

2000-10-01

432

Structure sensitivity and nanoscale effects in electrocatalysis.  

PubMed

This review discusses the role of the detailed nanoscale structure of catalytic surfaces on the activity of various electrocatalytic reactions of importance for fuel cells, hydrogen production, and other environmentally important catalytic reactions, such as carbon monoxide oxidation, methanol and ethanol oxidation, ammonia oxidation, nitric oxide reduction, hydrogen evolution, and oxygen reduction. Specifically, results and insights obtained from surface-science single-crystal-based model experiments are linked to experiments on well-defined shape-controlled nanoparticles. A classification of structure sensitive effects in electrocatalysis is suggested, based both on empirical grounds and on quantum-chemical viz. thermochemical considerations. The mutual relation between the two classification schemes is also discussed. The review underscores the relevance of single-crystal modeling of nanoscale effects in catalysis, and points to the special role of two kinds of active sites for electrocatalysis on nanoparticulate surfaces: (i) steps and defects in (111) terraces or facets, and (ii) long-range (100) terraces or facets. PMID:21399781

Koper, Marc T M

2011-05-01

433

A miniature broadband multilayer microstrip antenna  

Microsoft Academic Search

A novel compact broadband multilayer microstrip antenna is presented in this paper. The VSWR, gain and radiation pattern of this antenna are simulated. The measured VSWR of it is also shown in the paper. The results are discussed in detail.

Zhiwei Shi; Xi Deng; Yunlin Liu; Kun Chao

2008-01-01

434

Process for making a multilayer interconnect system  

NASA Technical Reports Server (NTRS)

A process for making an interconnect system for a multilayer circuit pattern. The interconnect system is formed having minimized through-hole space consumption so as to be suitable for high density, closely meshed circuit patterns.

Zachry, Clyde L. (Inventor); Niedzwiecke, Andrew J. (Inventor)

1976-01-01

435

Plasma etchback of multilayer printed wiring boards  

SciTech Connect

Removal of epoxy smear and glass fiber protrusions in multilayer printed wiring board holes was investigated. Gas plasma techniques, using a mixture of carbon tetrafluoride and oxygen, removed the eposies; however, the glass fibers were not affected.

Gentry, F.L.

1980-06-01

436

Classification Using Multi-Layered Perceptrons.  

National Technical Information Service (NTIS)

There has been an increasing interest in the applicability of neural networks in disparate domains. In this paper, we describe the use of multi-layered perceptrons, a type of neural network topology, for financial classification problems, with promising r...

J. A. Gentry M. J. Shaw S. Piramuthu

1990-01-01

437

The growth and applications of silicides for nanoscale devices  

NASA Astrophysics Data System (ADS)

Metal silicides have been used in silicon technology as contacts to achieve high device performance and desired device functions. The growth and applications of silicide materials have recently attracted increasing interest for nanoscale device applications. Nanoscale silicide materials have been demonstrated with various synthetic approaches. Solid state reaction wherein high quality silicides form through diffusion of metal atoms into silicon nano-templates and the subsequent phase transformation caught significant attention for the fabrication of nanoscale Si devices. Very interestingly, studies on the diffusion and phase transformation processes at the nanoscale have indicated possible deviations from the bulk and the thin film system. Here we present a review of fabrication, growth kinetics, electronic properties and device applications of nanoscale silicides formed through solid state reaction.Metal silicides have been used in silicon technology as contacts to achieve high device performance and desired device functions. The growth and applications of silicide materials have recently attracted increasing interest for nanoscale device applications. Nanoscale silicide materials have been demonstrated with various synthetic approaches. Solid state reaction wherein high quality silicides form through diffusion of metal atoms into silicon nano-templates and the subsequent phase transformation caught significant attention for the fabrication of nanoscale Si devices. Very interestingly, studies on the diffusion and phase transformation processes at the nanoscale have indicated possible deviations from the bulk and the thin film system. Here we present a review of fabrication, growth kinetics, electronic properties and device applications of nanoscale silicides formed through solid state reaction. This article was submitted as part of a collection highlighting papers on the `Recent Advances in Semiconductor Nanowires Research' from ICMAT 2011.

Lin, Yung-Chen; Chen, Yu; Huang, Yu

2012-02-01

438

Multilayer nanofilms as substrates for hepatocellular applications  

Microsoft Academic Search

Multilayer nanofilms, formed by the layer-by-layer (LbL) adsorption of positively and negatively charged polyelectrolytes, are promising substrates for tissue engineering. We investigate here the attachment and function of hepatic cells on multilayer films in terms of film composition, terminal layer, rigidity, charge, and presence of biofunctional species. Human hepatocellular carcinoma (HepG2) cells, adult rat hepatocytes (ARH), and human fetal hepatoblasts

Corinne R. Wittmer; Jennifer A. Phelps; Christin M. Lepus; William M. Saltzman; Martha J. Harding; Paul R. Van Tassel

2008-01-01

439

Multilayer recording in microholographic data storage  

NASA Astrophysics Data System (ADS)

The potential of multilayer recording in microholographic data storage is investigated. Micrometer-scaled depth localization of resolution-limited microgratings is achieved in photopolymers sensitized to green and violet light. Confocal readout results in an optical depth of approximately 2 ?m. The spatial Bragg selectivity of resolution-limited micrograting structures allows reducing their longitudinal depth spacing down to 4 ?m. Multilayer recording is demonstrated as depth multiplexing of microgratings written in 50 layer locations within a 300 ?m thick photopolymer.

Orlic, Susanna; Rass, Jens; Dietz, Enrico; Frohmann, Sven

2012-07-01

440

The B factor in multilayer thermionic refrigeration  

SciTech Connect

The figure of merit for multilayer thermionic refrigeration is discussed in terms of an effective B factor, which has a similar definition as the B factor in thermoelectrics. We show that high efficiencies for cooling or power generation are only obtained with very high values of this B factor. Such high values can only be attained because of the low thermal conductivity of multilayers. The B factor for thermionics is usually less than the one for thermoelectrics. (c) 1999 American Institute of Physics.

Vining, C. B. [ZT Services, 2203 Johns Circle, Auburn, Alabama 36830-7113 (United States)] [ZT Services, 2203 Johns Circle, Auburn, Alabama 36830-7113 (United States); Mahan, G. D. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, (United States) [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, (United States); Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6030 (United States)

1999-12-15

441

High-resolution Carbon/Carbon Multilayers  

NASA Astrophysics Data System (ADS)

To synthesize X-ray optical multilayers showing both high resolution and high reflectivity, spacer and absorber materials with low absorption coefficients for the desired spectral range are required. Beside the well-known candidates the material system Carbon / Carbon is interesting because of its low absorption coefficient over a wide spectral range and the opportunity, to deposit C-layers with different modifications, i.e. different optical properties. Simulations of C/C multilayers with different period thicknesses d and single layer densities ? show, that reflectivities R (Cu K? ) > 80% and a resolution ??~0.002° can be achieved for C/C layer stacks with d= 3 nm and N= 1000 periods. An advanced large area Pulsed Laser Deposition (LA-PLD) technology was used to deposit C/C multilayers on Si-substrates up to 4" diameter. The carbon film growth conditions for the spacer and absorber layers were optimised by the variation of selected laser parameters like pulse energy and ablation wavelength, to achieve a sufficient density contrast and smooth interfaces. C/C multilayers with period thickness d= 1.1...7.0 nm and more than 500 periods were deposited. The X-ray optical performance of the C/C multilayers was characterized by means of X-ray reflectometry. A reflectivity R > 50 % (CuK?) was measured for C/C multilayers with d= 17.2 nm and N= 106 periods. A peak resolution (??/?) ~ 1.1 % was obtained for a C/C multilayer structure with N= 80 periods and a period thickness d= 1.1nm. Results of TEM investigations indicate a regular morphology as well as smooth interfaces in the C-C layer stacks. Low compressive stresses were determined in C/C multilayers with different period thicknesses using X-ray diffraction techniques.

Baranov, Alexander M.; Dietsch, Reiner; Holz, Thomas; Menzel, Maik; Weissbach, Danny; Scholz, Roland; Melov, Valeri; Schreiber, Juergen

2002-12-01

442

Indirect heating of Pt by short-pulse laser irradiation of Au in a nanoscale Pt/Au bilayer  

NASA Astrophysics Data System (ADS)

Thermal transport in a metallic multilayer on picosecond time scales is controlled by the electronic thermal conductivity (?e), the electronic interfacial thermal conductance (Gee), and electron-phonon coupling constant (g). We analyze heat transfer in a nanoscale Pt/Au bilayer using data obtained in pump-probe measurements and modeling using a transmission-line-equivalent circuit. For optical exciation of either the Pt or Au side of the bilayer, the majority of energy is deposited into the Pt phonons on a time scale of ?1 ps because gPt?gAu and Gee>gAuhAu, where hAu is the thickness of the Au layer. We determine g of the Au layer and set a lower bound on Gee of the Pt/Au interface: gAu = 2.2 ± 0.6 × 1016 W m-3 K-1 and Gee > 5 GW m-2 K-1.

Choi, Gyung-Min; Wilson, R. B.; Cahill, David G.

2014-02-01

443

Microscale abrasive wear testing of duplex and non-duplex (single-layered) PVD (Ti,Al)N, TiN and Cr–N coatings  

Microsoft Academic Search

A micro-scale abrasive wear test, based on ball-cratering, has been used to evaluate the wear resistance of duplex and non-duplex (Ti,Al)N, TiN and Cr–N coatings. The term duplex is used here when plasma nitriding is followed by PVD coating. Coatings without the plasma nitriding stage are termed single-layered. Coating properties were evaluated by surface profilometry, hardness and scratch testing. All

J. C. A Batista; C. Godoy; A. Matthews

2002-01-01

444

High temperature wear resistance of (TiAl)N PVD coating on untreated and gas nitrided AISI H13 steel with different heat treatments  

Microsoft Academic Search

The wear resistance of a PVD (Ti0.7Al0.3)N coating deposited on an as-received and gas nitrided AISI H13 has been examined by using ball-on-disc tests at room temperature and at 600°C. In order to determine the influence of a previous heat treatment on this type of steel on the wear resistance of the (Ti0.7Al0.3)N coating, two commercial heat treatments were employed

R. Rodríguez-Baracaldo; J. A. Benito; E. S. Puchi-Cabrera; M. H. Staia

2007-01-01

445

Corrosion and erosion performance of HVOF\\/TiAlN PVD coatings and candidate materials for high pressure gate valve application  

Microsoft Academic Search

The main objective of this paper is to study the slurry erosion and corrosion behavior of WC10Co4Cr, Armcore ‘M’ Stellite 6 and 12 HVOF coatings, TiAlN PVD coating, selected steels, such as X20Cr13, 17Cr–4Ni pH steel and Ti6Al4V titanium alloy alongwith conventional hard weld deposits of Stellite 6 and 21. The slurry erosion studies were carried out at 60° angle

B. S. Mann; Vivek Arya; A. K. Maiti; M. U. B. Rao; Pankaj Joshi

2006-01-01

446

SUBSIDIZED INTEREST RATES AND RESTRICTED AGRICULTURAL CREDIT IN LDCs \\/ LES TAUX D'INTERET SUBVENTIONNES ET LA RESTRICTION DU CREDIT AGRICOLE DANS LES PVD  

Microsoft Academic Search

Le rôle du secteur agricole dans l'economie des PVD est aujourd'hui un fait acquis et de ce fait les gouvernements de ces pays ont tous entamé des programmes de devéloppement agricole. Parmi ces programmes il y a aussi des programmes de crédit agricole public à l'agriculture de subsistance visant à éliminer les contraintes les plus graves qui empèchent le devéloppement

François Kamajou

1980-01-01

447

Effect of interface roughness and coating thickness on interfacial shear mechanical properties of EB-PVD yttria-partially stabilized zirconia thermal barrier coating systems  

Microsoft Academic Search

The effect of interface roughness and thickness of thermal barrier coating (TBC) on the interfacial shear mechanical properties of electron beam-physical vapor deposited (EB-PVD)-TBC was examined using as-sprayed and polished bond coats (BC) 200?m and 500?m TBC thickness systems, by using a barb test method. The residual compressive stress in the TBC layer from the interface to the top surface

Shuqi Guo; Yoshihisa Tanaka; Yutaka Kagawa

2007-01-01

448

Charge–discharge studies on a lithium cell composed of PVdF-HFP polymer membranes prepared by phase inversion technique with a nanocomposite cathode  

Microsoft Academic Search

A novel polymer membrane of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) co-polymer was prepared by the phase inversion technique with two different non-solvents, 1-butanol or hexane. The prepared films were analyzed by scanning electron microscope (SEM) and nitrogen absorption\\/desorption techniques. The change in the morphology and pore diameter of the films prepared with different non-solvents correlates with the structure of the non-solvents used.

A Manuel Stephan; Dale Teeters

2003-01-01

449

Thermal cycling behavior of La 2Zr 2O 7 coating with the addition of Y 2O 3 by EB-PVD  

Microsoft Academic Search

Thermal barrier coatings (TBCs) of La2Zr2O7 (LZ) with the addition of 3wt.% Y2O3 (LZ3Y) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase structures, surface and cross-sectional morphologies, cyclic oxidation behaviors of these coatings were studied in detail. The thermal cycling test at 1373K in an air furnace indicates that the LZ3Y coating has a lifetime of 617 cycles

Zhenhua Xu; Limin He; Xiaolong Chen; Yu Zhao; Rende Mu; Shimei He; Xueqiang Cao

2010-01-01

450

Preparation and characterization of La 2Zr 2O 7 coating with the addition of Y 2O 3 by EB-PVD  

Microsoft Academic Search

Thermal barrier coatings (TBCs) of La2Zr2O7 (LZ) with the addition of 3wt.% Y2O3 (LZ3Y) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase stabilities, thermophysical and mechanical properties, and chemical compositions of these ceramics and coatings were studied in detail. The phase stability and thermal expansion behavior of LZ3Y bulk material are identical to those of LZ bulk material,

Zhenhua Xu; Limin He; Rende Mu; Shimei He; Xueqiang Cao

2010-01-01

451

Performance of PVD TiN\\/TaN and TiN\\/NbN superlattice coated cemented carbide tools in stainless steel machining  

Microsoft Academic Search

Cemented carbide cutting tools coated with superlattice TiN\\/TaN and TiN\\/NbN lamellae thin films were evaluated in face milling machining tests of austenitic stainless steel (AISI\\/SAE 303\\/304). The coatings were grown by PVD on cemented carbide inserts by a combination of ion plating of TiN and reactive magnetron sputtering of NbN and TaN. The lamellae coatings were macroscopically disordered as a

T. I Selinder; M. E Sjöstrand; M Nordin; M Larsson; Å Östlund; S Hogmark

1998-01-01

452

Structure and transport properties of polymer gel electrolytes based on PVdF-HFP and LiN(C 2F 5SO 2) 2  

Microsoft Academic Search

Gel polymer electrolytes composed of PVdF\\/HFP and a non-aqueous lithium electrolyte solution EC\\/DEC\\/LiN(C2F5SO2)2 (BETI) were prepared to investigate the conduction properties of the gel materials. Structural and micro-structural characterization was carried out by means of modulated differential scanning calorimetry (MDSC) and scanning electron microscopy (SEM). The samples with polymer\\/solution weight ratios higher than 0.5 contain at least an amorphous swollen

Claudio Capiglia; Yuria Saito; Hiroshi Kataoka; Teruo Kodama; Eliana Quartarone; Piercarlo Mustarelli

2000-01-01

453

Polyvinylidene fluoride–hexafluoropropylene (PVdF–HFP)-based composite polymer electrolyte containing LiPF 3(CF 3CF 2) 3  

Microsoft Academic Search

This paper describes the preparation and characterization of lithium fluoroalkylphosphate-containing composite polymer electrolyte based on a polyvinylidene fluoride–hexafluoropropylene (PVdF–HFP) matrix. A mixture of ethylene carbonate and diethyl carbonate was used as a plasticizing agent and nanoscopic Al2O3 as a filler. The membranes were characterized by ac impedance, SEM, DSC, FTIR and fluorescence. An electrolyte with 2.5wt% Al2O3 exhibited a conductivity

V. Aravindan; P. Vickraman; T. Prem Kumar

2008-01-01

454

Effects of TiO2 and ZrO2 nanofillers in LiBOB based PVdF\\/PVC composite polymer electrolytes (CPE)  

Microsoft Academic Search

A novel type of lithium bis(oxalato)borate (LiBOB) synthesized by the solid-state reaction method has been presented. LiBOB composite polymer electrolytes (CPE) prepared with dispersions of TIO2\\/ZrO2with various concentrations into the host blend matrices of poly(vinylidenefluoride) (PVdF)-poly(vinylchloride) (PVC) are investigated by scanning electron microscopy, x-ray diffraction (XRD) and ac impedance measurements. The plasticizing agent selected for the present study is a

V. Aravindan; P. Vickraman

2007-01-01

455

Highly conductive and electrochemically stable plasticized blend polymer electrolytes based on PVdF-HFP and triblock copolymer PPG-PEG-PPG diamine for Li-ion batteries  

Microsoft Academic Search

A new plasticized poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP)\\/PPG-PEG-PPG diamine\\/organosilane blend-based polymer electrolyte system has been synthesized and characterized. The structural and electrochemical properties of the electrolytes thus obtained were systematically investigated by a variety of techniques including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile test, Fourier transform infrared spectroscopy (FTIR), 13C and 29Si solid-state NMR, AC impedance, linear sweep voltammetry (LSV)

Diganta Saikia; Hao-Yiang Wu; Yu-Chi Pan; Chi-Pin Lin; Kai-Pin Huang; Kan-Nan Chen; George T. K. Fey; Hsien-Ming Kao

2011-01-01

456

Investigations on friction and wear mechanisms of the PVD-TiAlN coated carbide in dry sliding against steels and cast iron  

Microsoft Academic Search

The tribological behaviour of the monolayer PVD-titanium aluminium nitride (TiAlN) coated carbide inserts in unidirectional dry sliding against steel and cast iron counterparts was investigated using the pin-on-disc standard test with varying sliding speeds and normal loads. Three different materials of various machinability rates were used as the counterparts, namely the normalised medium carbon steel C45 equivalent to AISI 1045,

W. Grzesik; Z. Zalisz; S. Krol; P. Nieslony

2006-01-01

457

Design and performance of AlTiN and TiAlCrN PVD coatings for machining of hard to cut materials  

Microsoft Academic Search

Machining of hard to cut materials such as hardened steels and high temperature strong aerospace materials is a challenge of modern manufacturing. Two categories of the aluminum-rich TiAlN-based Physical Vapor Deposited (PVD) coatings, namely AlTiN and TiAlCrN, are commonly used for this area of application. A comparative investigation of the structural characteristics, various micro-mechanical properties, oxidation resistance and service properties

G. S. Fox-Rabinovich; A. I. Kovalev; M. H. Aguirre; B. D. Beake; K. Yamamoto; S. C. Veldhuis; J. L. Endrino; D. L. Wainstein; A. Y. Rashkovskiy

2009-01-01

458

The effect of oxidation pre-treatment on the cyclic life of EB-PVD thermal barrier coatings with platinum–aluminide bond coats  

Microsoft Academic Search

A simple method of improving the durability of EB-PVD thermal barrier coatings (TBC) based on pre-oxidation of the bond coat is described. The method produces a twofold increase in TBC cyclic life and is effective in postponing the two major types of the oxidation-induced failure typical of TBC systems with platinum–aluminide bond coats: the gradual growth of separations between the

V. K. Tolpygo; D. R. Clarke

2005-01-01

459

Laterally graded multilayer double-monochromator.  

SciTech Connect

The authors describe a tunable multilayer monochromator with an adjustable bandpass to be used for reflectivity and grazing incidence diffraction studies on surfaces at energies near 10 keV. Multilayers have a bandpass typically 100 times larger than the Si(111) reflection, and by using multilayers an experimenter can significantly increase data collection rates over those available with a Si monochromator. The transmission through 1 and 2 laterally graded multilayer (LGML) reflections was recorded versus photon energy. The identical LGMLs were comprised of 60 bilayers of W and C on 100 x 25 x 3 mm float glass with a bilayer spacing varying from 35 to 60 {angstrom}. The average gradient was 0.27 {angstrom}/mm along the long dimension. The rms deviation of the data for the bilayer spacing from a linear fit was 0.36 {angstrom}. Data were obtained for a nondispersive ({+-}) double-multilayer arrangement. The relative bandpass width (FWHM) when the two multilayers exposed the same bilayer spacing was measured to be 2.2% with a transmission of 78.7 {+-} 1.6%. This value is consistent with the transmission of 88.9% that they also measured for a single LGML at HASYLAB beamline D4. The bandpass was tunable in the range 1.1% to 2.2%.

Als-Nielsen, J.; Erdmann, J.; Gaarde, P.; Krasnicki, S.; Liu, C.; Macrander, A. T.; Maj, J.; Mancini, D.

1999-09-01

460

Thermal stability, complexing behavior, and ionic transport of polymeric gel membranes based on polymer PVdF-HFP and ionic liquid, [BMIM][BF4].  

PubMed

PVdF-HFP + IL(1-butyl-3-methylimidazolium tetrafluoroborate; [BMIM][BF(4)]) polymeric gel membranes containing different amounts of ionic liquid have been synthesized and characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared (FTIR), differential scanning calorimetry, thermogravimetric analysis (TGA), and complex impedance spectroscopic techniques. Incorporation of IL in PVdF-HFP polymer changes different physicochemical properties such as melting temperature (T(m)), thermal stability, structural morphology, amorphicity, and ionic transport. It is shown by FTIR, TGA (also first derivative of TGA, "DTGA") that IL partly complexes with the polymer PVdF-HFP and partly remains dispersed in the matrix. The ionic conductivity of polymeric gel membranes has been found to increase with increasing concentration of IL and attains a maximum value of 1.6 × 10(-2) S·cm(-1) for polymer gel membrane containing 90 wt % IL at room temperature. Interestingly, the values of conductivity of membranes with 80 and 90 wt % of IL were higher than that of pure IL (100 wt %). The polymer chain breathing model has been suggested to explain it. The variation of ionic conductivity with temperature of these gel polymeric membranes follows Arrhenius type thermally activated behavior. PMID:23167848

Shalu; Chaurasia, S K; Singh, R K; Chandra, S

2013-01-24

461

Technologies for manufacturing of high angular resolution multilayer coated optics for the New Hard X-ray Mission  

NASA Astrophysics Data System (ADS)

In the frame of the technology development to be used for the Optical Payload of next future X-ray missions (such as e.g. New Hard X-ray Mission-ASI), a new set of manufacturing techniques were finalized by Media Lario Technologies (MLT), in collaboration with the Italian Space Agency (ASI) and the Brera Astronomical Observatory (INAF/OAB). The set of new technologies includes master manufacturing machines and processes, electroforming method, a vertical optical bench and metrology machines to support manufacturing and integration of mirrors. A magnetron sputtering PVD machine was upgraded and a Pt/C development study has been performed on the basis of the W/Si results obtained in the first phase of the study. New manufacturing technologies for highly accurate masters were developed and tested by mean of two full-size masters together with several dummies. A number of ultrathin Nickel-Cobalt focusing mirrors were manufactured via galvanic replication process from the masters and coated with Pt/C multilayer. Tests on substrate material, roughness and shape of the shell together with analysis on specimens were performed. Tests with AFM and XRR supported the development of the Pt/C multilayer which is the enabling technology for focusing high energy X-Rays. Several mirror shells were integrated into two demonstrator modules to assess the whole manufacturing process up to optical payload integration. The summary of the results from manufacturing and testing of specimens and mirror shells is reported in this paper together with a description of the technologies now available at MLT.

Orlandi, A.; Basso, S.; Borghi, G.; Binda, R.; Citterio, O.; Grisoni, G.; Kools, J.; Marioni, F.; Missaglia, N.; Negri, B.; Negri, R.; Pareschi, G.; Raimondi, L.; Ritucci, A.; Salmaso, B.; Sironi, G.; Spiga, D.; Subranni, R.; Tagliaferri, G.; Valsecchi, G.; Vernani, D.

2011-05-01

462

Phase separation and formation of the self-organised layered nanostructure in C\\/Cr coatings in conditions of high ion irradiation  

Microsoft Academic Search

The paper discusses the effect of ion irradiation on a new type of nanoscale multilayer structure in C\\/Cr PVD coatings formed by a self-organisation mechanism. C\\/Cr coatings were deposited by the combined steered cathodic arc\\/unbalanced magnetron sputtering technique, at wide range of bias voltages, Ub from ?65 to ?550 V. Plasma diagnostics carried out by electrostatic probe measurements revealed that

P. Eh. Hovsepian; Y. N. Kok; A. P. Ehiasarian; R. Haasch; J.-G. Wen; I. Petrov

2005-01-01

463

Fine tuning of activity for nanoscale catalysts.  

SciTech Connect

Ability to tune the electronic and structural properties of nanocatalysts can potentially lead towards the superior catalytic enhancement that was reported for the Pt{sub 3}Ni(111)-skin surface. Here we report investigation of the extended well-defined surfaces of Pt and PtM alloys (M=Ni,Co,Fe,V,Ti,Re) as well as Pt(hkl) single crystalline surfaces for various catalytic reaction. The electrode surfaces were initially characterized in ultra-high vacuum by AES, LEIS and UPS before controlled transfer into electrochemical environment. Catalytic properties have been determined in three compartment electrochemical cell for oxygen reduction reaction (ORR) by rotational disk electrode technique. The single crystalline surfaces of Pt electrodes have been used to benchmark the activity range that could be expected on pure Pt electrodes. We have proposed that surface modifications induced by the second metal, and consequent catalytic enhancements could occur through the following effects: (1) Electronic effect, due to changes in the metallic d-band center position vs. Fermi level; and (2) Structural effect, which reflects relationship between atomic geometry, and/or surface chemistry, i.e., dissolution - surface roughening. It has been reported that Pt bimetallic alloys, could form surfaces with two different compositions. Due to surface segregation annealed surfaces can form the outermost Pt-skin surface layer, while the lightly sputtered surfaces have the bulk ratio of alloying components and form Pt-skeleton outermost layers as a result of dissolution of non-precious atoms. In principle, different near-surface compositions (Pt-skin, Pt-skeleton and polycrystalline Pt) have been found to have different electronic structures. Modification in Pt electronic properties alters adsorption/catalytic properties of corresponding materials. The most active systems for the electrochemical oxygen reduction reaction (ORR) are established to be the Pt-skin near-surface formation. The similar levels of catalytic enhancement have been established for corresponding nanoscale materials. In addition to electronic properties we have found how catalytic activity could be affected by the arrangement of surface defects on nanoscale surfaces. Ability to control surface and near surface catalyst properties enables fine tuning of catalytic activity and stability of nanoscale surfaces.

Strmcnik, D.; van derVliet, D.; Lucas, C.; Karapetrov, G.; Markovic, N.; Stamenkovic, V.; Materials Science Division

2008-01-01

464

MoRu/Be multilayers for extreme ultraviolet applications  

DOEpatents

High reflectance, low intrinsic roughness and low stress multilayer systems for extreme ultraviolet (EUV) lithography comprise amorphous layers MoRu and crystalline Be layers. Reflectance greater than 70% has been demonstrated for MoRu/Be multilayers with 50 bilayer pairs. Optical throughput of MoRu/Be multilayers can be 30-40% higher than that of Mo/Be multilayer coatings. The throughput can be improved using a diffusion barrier to make sharper interfaces. A capping layer on the top surface of the multilayer improves the long-term reflectance and EUV radiation stability of the multilayer by forming a very thin native oxide that is water resistant.

Bajt, Sasa C. (Livermore, CA) [Livermore, CA; Wall, Mark A. (Stockton, CA) [Stockton, CA

2001-01-01

465

Systematic modification of the rheological properties of colloidal suspensions with polyelectrolyte multilayers  

NASA Astrophysics Data System (ADS)

Tailoring rheological properties of colloidal suspensions with the adsorption of polyelectrolyte multilayers (PEMs) is based on the idea of controlling macroscopic mechanical properties by modifying the particle surface in a reproducible and well-understood manner. With layer-by-layer self-assembly, monodisperse polystyrene particles are coated with up to ten layers of the oppositely charged strong polyelectrolytes: poly(diallyl dimethyl ammonium chloride) and poly(styrene sulfonate). The conformation of the adsorbed polyelectrolyte is controlled by the ionic strength of the used aqueous polyelectrolyte solution. For 1M NaCl solution, a brushlike adsorption of the polyelectrolyte is expected. The ability of PEMs to serve on a nanoscale level as surface modifiers and influence macroscopic rheological properties like viscoelasticity, yield stress, and shear banding is discussed. The mechanical behavior of these suspensions is qualitatively described by the theory of Derjaguin-Landau-Verwey-Overbeek with short-range repulsion and long-range attraction. A scaling rule is proposed which distinguishes between the precusor and the multilayer regime.

Hess, Andreas; Pretzl, Melanie; Heymann, Lutz; Fery, Andreas; Aksel, Nuri