Ferroelectric properties of PZT/BFO multilayer thin films prepared using the sol-gel method.

PubMed

Jo, Seo-Hyeon; Lee, Sung-Gap; Lee, Young-Hie

2012-01-05

In this study, Pb(Zr0.52Ti0.48)O3/BiFeO3 [PZT/BFO] multilayer thin films were fabricated using the spin-coating method on a Pt(200 nm)/Ti(10 nm)/SiO2(100 nm)/p-Si(100) substrate alternately using BFO and PZT metal alkoxide solutions. The coating-and-heating procedure was repeated several times to form the multilayer thin films. All PZT/BFO multilayer thin films show a void-free, uniform grain structure without the presence of rosette structures. The relative dielectric constant and dielectric loss of the six-coated PZT/BFO [PZT/BFO-6] thin film were approximately 405 and 0.03%, respectively. As the number of coatings increased, the remanent polarization and coercive field increased. The values for the BFO-6 multilayer thin film were 41.3 C/cm2 and 15.1 MV/cm, respectively. The leakage current density of the BFO-6 multilayer thin film at 5 V was 2.52 × 10-7 A/cm2.

A functional protein retention and release multilayer with high stability

NASA Astrophysics Data System (ADS)

Nie, Kun; An, Qi; Zhang, Yihe

2016-04-01

Effective and robust interfacial protein retention lies at the heart of the fabrication of protein-based functional interfaces, which is potentially applicable in catalysis, medical therapy, antifouling, and smart devices, but remains challenging due to the sensitive nature of proteins. This study reports a general protein retention strategy to spatial-temporally confine various types of proteins at interfacial regions. The proteins were preserved in mesoporous silica nanoparticles embedded in covalently woven multilayers. It is worth noting that the protein retention strategy effectively preserves the catalytic capabilities of the proteins, and the multilayer structure is robust enough to withstand the bubbling catalytic reactions and could be repeatedly used due to conservation of proteins. The spatiotemporal retention of proteins could be adjusted by varying the number of capping layers. Furthermore, we demonstrate that the protein-loaded interfacial layers could not only be used to construct catalytic-active interfaces, but also be integrated as the power-generating unit to propel a macroscopic floating device.Effective and robust interfacial protein retention lies at the heart of the fabrication of protein-based functional interfaces, which is potentially applicable in catalysis, medical therapy, antifouling, and smart devices, but remains challenging due to the sensitive nature of proteins. This study reports a general protein retention strategy to spatial-temporally confine various types of proteins at interfacial regions. The proteins were preserved in mesoporous silica nanoparticles embedded in covalently woven multilayers. It is worth noting that the protein retention strategy effectively preserves the catalytic capabilities of the proteins, and the multilayer structure is robust enough to withstand the bubbling catalytic reactions and could be repeatedly used due to conservation of proteins. The spatiotemporal retention of proteins could be adjusted by varying the number of capping layers. Furthermore, we demonstrate that the protein-loaded interfacial layers could not only be used to construct catalytic-active interfaces, but also be integrated as the power-generating unit to propel a macroscopic floating device. Electronic supplementary information (ESI) available: UV-vis spectra of the substrate covered by only polymeric (PAH/PAA)5/(PAH/DAS)5 multilayers, UV-vis spectra of the covalently cross-linked (PAH/SiO2 NP)5/(PAH/DAS)5 hybrid multilayers and (CAT/PAH)5/(PAH/DAS)5 films. TEM of the mesoporous silica. See DOI: 10.1039/c6nr01671e

Large area polysilicon films with predetermined stress characteristics and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor); Phillips, Stephen M. (Inventor)

2002-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin films may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films. Multi-layer assemblies exhibiting selectively determinable overall bending moments are also disclosed. Selective production of overall bending moments in microstructures enables manufacture of such structures with a wide array of geometrical configurations.

Ordered organic-organic multilayer growth

DOEpatents

Forrest, Stephen R.; Lunt, Richard R.

2016-04-05

An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

Ordered organic-organic multilayer growth

DOEpatents

Forrest, Stephen R; Lunt, Richard R

2015-01-13

An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

Magnetic damping phenomena in ferromagnetic thin-films and multilayers

NASA Astrophysics Data System (ADS)

Azzawi, S.; Hindmarch, A. T.; Atkinson, D.

2017-11-01

Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.

Multilayer composites and manufacture of same

DOEpatents

Holesinger, Terry G.; Jia, Quanxi

2006-02-07

The present invention is directed towards a process of depositing multilayer thin films, disk-shaped targets for deposition of multilayer thin films by a pulsed laser or pulsed electron beam deposition process, where the disk-shaped targets include at least two segments with differing compositions, and a multilayer thin film structure having alternating layers of a first composition and a second composition, a pair of the alternating layers defining a bi-layer wherein the thin film structure includes at least 20 bi-layers per micron of thin film such that an individual bi-layer has a thickness of less than about 100 nanometers.

Correction: Mesoporous titania thin films as efficient enzyme carriers for paraoxon determination/detoxification: effects of enzyme binding and pore hierarchy on the biocatalyst activity and reusability.

PubMed

Frančič, N; Bellino, M G; Soler-Illia, G J A A; Lobnik, A

2016-07-07

Correction for 'Mesoporous titania thin films as efficient enzyme carriers for paraoxon determination/detoxification: effects of enzyme binding and pore hierarchy on the biocatalyst activity and reusability' by N. Frančičet al., Analyst, 2014, 139, 3127-3136.

Ferroelectric properties of PZT/BFO multilayer thin films prepared using the sol-gel method

PubMed Central

2012-01-01

In this study, Pb(Zr0.52Ti0.48)O3/BiFeO3 [PZT/BFO] multilayer thin films were fabricated using the spin-coating method on a Pt(200 nm)/Ti(10 nm)/SiO2(100 nm)/p-Si(100) substrate alternately using BFO and PZT metal alkoxide solutions. The coating-and-heating procedure was repeated several times to form the multilayer thin films. All PZT/BFO multilayer thin films show a void-free, uniform grain structure without the presence of rosette structures. The relative dielectric constant and dielectric loss of the six-coated PZT/BFO [PZT/BFO-6] thin film were approximately 405 and 0.03%, respectively. As the number of coatings increased, the remanent polarization and coercive field increased. The values for the BFO-6 multilayer thin film were 41.3 C/cm2 and 15.1 MV/cm, respectively. The leakage current density of the BFO-6 multilayer thin film at 5 V was 2.52 × 10-7 A/cm2. PMID:22221519

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

2008-05-06

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

1999-01-01

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, P.J.; Baskaran, S.; Bontha, J.R.; Liu, J.

1999-07-13

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s). 24 figs.

Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Hadi, Aseel; Alhabradi, Mansour; Chen, Qian; Liu, Hong; Guo, Wei; Curioni, Michele; Cernik, Robert; Liu, Zhu

2018-01-01

In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO2 thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO2 nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO2 thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO2 photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO2 film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO2 thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.

Hydrothermal performance of catalyst supports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elam, Jeffrey W.; Marshall, Christopher L.; Libera, Joseph A.

A high surface area catalyst with a mesoporous support structure and a thin conformal coating over the surface of the support structure. The high surface area catalyst support is adapted for carrying out a reaction in a reaction environment where the thin conformal coating protects the support structure within the reaction environment. In various embodiments, the support structure is a mesoporous silica catalytic support and the thin conformal coating comprises a layer of metal oxide resistant to the reaction environment which may be a hydrothermal environment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Shengwei; Yu Jiaguo

Bi{sub 2}WO{sub 6} hierarchical multilayered flower-like assemblies are fabricated on a large scale by a simple hydrothermal method in the presence of polymeric poly(sodium 4-styrenesulfonate). Such 3D Bi{sub 2}WO{sub 6} assemblies are constructed from orderly arranged 2D layers, which are further composed of a large number of interconnected nanoplates with a mean side length of ca. 50 nm. The bimodal mesopores associated with such hierarchical assembly exhibit peak mesopore size of ca. 4 nm for the voids within a layer, and peak mesopore size of ca. 40 nm corresponding to the interspaces between stacked layers, respectively. The formation process ismore » discussed on the basis of the results of time-dependent experiments, which support a novel 'coupled cooperative assembly and localized ripening' formation mechanism. More interestingly, we have noticed that the collective effect related to such hierarchical assembly induces a significantly enhanced optical absorbance in the UV-visible region. This work may shed some light on the design of complex architectures and exploitation of their potential applications. - Graphical abstract: Bi{sub 2}WO{sub 6} hierarchical multilayered flower-like assemblies are fabricated on a large scale by a simple hydrothermal method in the presence of polymeric poly(sodium 4-styrenesulfonate)« less

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

PubMed Central

Dumée, Ludovic F.; She, Fenghua; Duke, Mikel; Gray, Stephen; Hodgson, Peter; Kong, Lingxue

2014-01-01

Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm) as well as the sintering pressure (5–20 ton·m−2) and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested. PMID:28344241

Continuous planar phospholipid bilayer supported on porous silicon thin film reflector.

PubMed

Cunin, Frédérique; Milhiet, Pierre-Emmanuel; Anglin, Emily; Sailor, Michael J; Espenel, Cédric; Le Grimellec, Christian; Brunel, Daniel; Devoisselle, Jean-Marie

2007-10-01

Reconstituting artificial membranes for in vitro studies of cell barrier mechanisms and properties is of major interest in biology. Here, artificial membranes supported on porous silicon photonic crystal reflectors are prepared and investigated. The materials are of interest for label-free probing of supported membrane events such as protein binding, molecular recognition, and transport. The porous silicon substrates are prepared as multilayered films consisting of a periodically varying porosity, with pore dimensions of a few nanometers in size. Planar phospholipid bilayers are deposited on the topmost surface of the oxidized hydrophilic mesoporous silicon films. Atomic force microscopy provides evidence of continuous bilayer deposition at the surface, and optical measurements indicate that the lipids do not significantly infiltrate the porous region. The presence of the supported bilayer does not obstruct the optical spectrum from the porous silicon layer, suggesting that the composite structures can act as effective optical biosensors.

Multilayer encapsulated mesoporous silica nanospheres as an oral sustained drug delivery system for the poorly water-soluble drug felodipine.

PubMed

Hu, Liang; Sun, Hongrui; Zhao, Qinfu; Han, Ning; Bai, Ling; Wang, Ying; Jiang, Tongying; Wang, Siling

2015-02-01

We used a combination of mesoporous silica nanospheres (MSN) and layer-by-layer (LBL) self-assembly technology to establish a new oral sustained drug delivery system for the poorly water-soluble drug felodipine. Firstly, the model drug was loaded into MSN, and then the loaded MSN were repeatedly encapsulated by chitosan (CHI) and acacia (ACA) via LBL self-assembly method. The structural features of the samples were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption. The encapsulating process was monitored by zeta-potential and surface tension measurements. The physical state of the drug in the samples was characterized by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The influence of the multilayer with different number of layers on the drug release rate was studied using thermal gravimetric analysis (TGA) and surface tension measurement. The swelling effect and the structure changes of the multilayer were investigated to explore the relationship between the drug release behavior and the state of the multilayer under different pH conditions. The stability and mucosa adhesive ability of the prepared nanoparticles were also explored. After multilayer coating, the drug release rate was effectively controlled. The differences in drug release behavior under different pH conditions could be attributed to the different states of the multilayer. And the nanoparticles possessed good stability and strong mucosa adhesive ability. We believe that this combination offers a simple strategy for regulating the release rate of poorly water-soluble drugs and extends the pharmaceutical applications of inorganic materials and polymers. Copyright © 2014 Elsevier B.V. All rights reserved.

Multi-layered, chemically bonded lithium-ion and lithium/air batteries

DOEpatents

Narula, Chaitanya Kumar; Nanda, Jagjit; Bischoff, Brian L; Bhave, Ramesh R

2014-05-13

Disclosed are multilayer, porous, thin-layered lithium-ion batteries that include an inorganic separator as a thin layer that is chemically bonded to surfaces of positive and negative electrode layers. Thus, in such disclosed lithium-ion batteries, the electrodes and separator are made to form non-discrete (i.e., integral) thin layers. Also disclosed are methods of fabricating integrally connected, thin, multilayer lithium batteries including lithium-ion and lithium/air batteries.

Molten Salt Assisted Self-Assembly: Synthesis of Mesoporous LiCoO2 and LiMn2 O4 Thin Films and Investigation of Electrocatalytic Water Oxidation Performance of Lithium Cobaltate.

PubMed

Saat, Gülbahar; Balci, Fadime Mert; Alsaç, Elif Pınar; Karadas, Ferdi; Dag, Ömer

2018-01-01

Mesoporous thin films of transition metal lithiates (TML) belong to an important group of materials for the advancement of electrochemical systems. This study demonstrates a simple one pot method to synthesize the first examples of mesoporous LiCoO 2 and LiMn 2 O 4 thin films. Molten salt assisted self-assembly can be used to establish an easy route to produce mesoporous TML thin films. The salts (LiNO 3 and [Co(H 2 O) 6 ](NO 3 ) 2 or [Mn(H 2 O) 4 ](NO 3 ) 2 ) and two surfactants (10-lauryl ether and cethyltrimethylammonium bromide (CTAB) or cethyltrimethylammonium nitrate (CTAN)) form stable liquid crystalline mesophases. The charged surfactant is needed for the assembly of the necessary amount of salt in the hydrophilic domains of the mesophase, which produces stable metal lithiate pore-walls upon calcination. The films have a large pore size with a high surface area that can be increased up to 82 m 2 g -1 . The method described can be adopted to synthesize other metal oxides and metal lithiates. The mesoporous thin films of LiCoO 2 show promising performance as water oxidation catalysts under pH 7 and 14 conditions. The electrodes, prepared using CTAN as the cosurfactant, display the lowest overpotentials in the literature among other LiCoO 2 systems, as low as 376 mV at 10 mA cm -2 and 282 mV at 1 mA cm -2 . © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein-Containing Multilayer Capsules by Templating on Mesoporous CaCO3 Particles: POST- and PRE-Loading Approaches.

PubMed

Balabushevich, Nadezhda G; Lopez de Guerenu, Anna V; Feoktistova, Natalia A; Skirtach, Andre G; Volodkin, Dmitry

2016-01-01

Encapsulation of model proteins (catalase, insulin, aprotinin) into multilayer dextran sulphate/protamin capsules by templating on CaCO3 microparticles is investigated employing: (i) PRE-loading into CaCO3 particles by adsorption or co-synthesis and (ii) POST-loading into performed capsules. Protein encapsulation is governed by both its size and electrostatic interactions with the carbonate microparticles and multilayer shell. PRE-loading enables improved encapsulation compared to POST-loading (catalase content in capsules 630 and 70 mg · g(-1)). Bioactivity of encapsulated protein is not affected by interaction with multilayers but may be reduced at slightly alkaline pH due to CaCO3 hydrolysis. This study might help to successfully encapsulate fragile bio-macromolecules into multilayer capsules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mesoporous polyaniline film on ultra-thin graphene sheets for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Qian; Yan, Jun; Fan, Zhuangjun; Wei, Tong; Zhang, Milin; Jing, Xiaoyan

2014-02-01

A facile approach has been developed to fabricate mesoporous PANI film on ultra-thin graphene nanosheet (G-mPANI) hybrid by in situ polymerization using graphene-mesoporous silica composite as template. Due to its mesoporous structure, over-all conductive network, G-mPANI electrode displays a specific capacitance of 749 F g-1 at 0.5 A g-1 with excellent rate capability (remains 73% even at 5.0 A g-1), much higher than that of pristine PANI electrode (315 F g-1 at 0.5 A g-1, 39% retention at 5.0 A g-1) in 1 mol L-1 H2SO4 aqueous solution. More interestingly, the G-mPANI hybrid can maintain 88% of its initial capacitance compared to 45% for pristine PANI after 1000 cycles, suggesting a superior electrochemical cyclic stability.

Multilayer SnSb4-SbSe Thin Films for Phase Change Materials Possessing Ultrafast Phase Change Speed and Enhanced Stability.

PubMed

Liu, Ruirui; Zhou, Xiao; Zhai, Jiwei; Song, Jun; Wu, Pengzhi; Lai, Tianshu; Song, Sannian; Song, Zhitang

2017-08-16

A multilayer thin film, comprising two different phase change material (PCM) components alternatively deposited, provides an effective means to tune and leverage good properties of its components, promising a new route toward high-performance PCMs. The present study systematically investigated the SnSb 4 -SbSe multilayer thin film as a potential PCM, combining experiments and first-principles calculations, and demonstrated that these multilayer thin films exhibit good electrical resistivity, robust thermal stability, and superior phase change speed. In particular, the potential operating temperature for 10 years is shown to be 122.0 °C and the phase change speed reaches 5 ns in the device test. The good thermal stability of the multilayer thin film is shown to come from the formation of the Sb 2 Se 3 phase, whereas the fast phase change speed can be attributed to the formation of vacancies and a SbSe metastable phase. It is also demonstrated that the SbSe metastable phase contributes to further enhancing the electrical resistivity of the crystalline state and the thermal stability of the amorphous state, being vital to determining the properties of the multilayer SnSb 4 -SbSe thin film.

Theory and practical considerations of multilayer dielectric thin-film stacks in Ag-coated hollow waveguides.

PubMed

Bledt, Carlos M; Melzer, Jeffrey E; Harrington, James A

2014-02-01

This analysis explores the theory and design of dielectric multilayer reflection-enhancing thin film stacks based on high and low refractive index alternating layers of cadmium sulfide (CdS) and lead sulfide (PbS) on silver (Ag)-coated hollow glass waveguides (HGWs) for low loss transmission at midinfrared wavelengths. The fundamentals for determining propagation losses in such multilayer thin-film-coated Ag hollow waveguides is thoroughly discussed, and forms the basis for further theoretical analysis presented in this study. The effects on propagation loss resulting from several key parameters of these multilayer thin film stacks is further explored in order to bridge the gap between results predicted through calculation under ideal conditions and deviations from such ideal models that often arise in practice. In particular, the effects on loss due to the number of dielectric thin film layers deposited, deviation from ideal individual layer thicknesses, and surface roughness related scattering losses are presented and thoroughly investigated. Through such extensive theoretical analysis the level of understanding of the underlying loss mechanisms of multilayer thin-film Ag-coated HGWs is greatly advanced, considerably increasing the potential practical development of next-generation ultralow-loss mid-IR Ag/multilayer dielectric-coated HGWs.

Degradation product analysis from the photocatalytic oxidation/reduction of 2,4-dichlorophenol in the presence of mesoporous silica encapsulated TiO2 particles and TiO2 dispersions (presentation)

EPA Science Inventory

Thin films of Degussa P-25 TiO2 encapsulated in an SBA-15 mesoporous silica matrix were prepared. The TiO2/SBA-15 thin film structure was verified using transmission electron microscopy (TEM) and small angle X-ray diffraction (XRD). During irradiation with 350 nm light, the TiO...

Atomically Thin Mesoporous Nanomesh of Graphitic C₃N₄ for High-Efficiency Photocatalytic Hydrogen Evolution.

PubMed

Han, Qing; Wang, Bing; Gao, Jian; Cheng, Zhihua; Zhao, Yang; Zhang, Zhipan; Qu, Liangti

2016-02-23

Delamination of layer materials into two-dimensional single-atom sheets has induced exceptional physical properties, including large surface area, ultrahigh intrinsic carrier mobility, pronounced changes in the energy band structure, and other properties. Here, atomically thin mesoporous nanomesh of graphitic carbon nitride (g-C3N4) is fabricated by solvothermal exfoliation of mesoporous g-C3N4 bulk made from thermal polymerization of freeze-drying assembled Dicyandiamide nanostructure precursor. With the unique structural advantages for aligned energy levels, electron transfer, light harvesting, and the richly available reaction sites, the as-prepared monolayer of mesoporous g-C3N4 nanomesh exhibits a superior photocatalytic hydrogen evolution rate of 8510 μmol h(-1) g(-1) under λ > 420 nm and an apparent quantum efficiency of 5.1% at 420 nm, the highest of all the metal-free g-C3N4 nanosheets photocatalysts.

Indentation-derived elastic modulus of multilayer thin films: Effect of unloading induced plasticity

DOE PAGES

Jamison, Ryan Dale; Shen, Yu -Lin

2015-08-13

Nanoindentation is useful for evaluating the mechanical properties, such as elastic modulus, of multilayer thin film materials. A fundamental assumption in the derivation of the elastic modulus from nanoindentation is that the unloading process is purely elastic. In this work, the validity of elastic assumption as it applies to multilayer thin films is studied using the finite element method. The elastic modulus and hardness from the model system are compared to experimental results to show validity of the model. Plastic strain is shown to increase in the multilayer system during the unloading process. Additionally, the indentation-derived modulus of a monolayermore » material shows no dependence on unloading plasticity while the modulus of the multilayer system is dependent on unloading-induced plasticity. Lastly, the cyclic behavior of the multilayer thin film is studied in relation to the influence of unloading-induced plasticity. Furthermore, it is found that several cycles are required to minimize unloading-induced plasticity.« less

Method for measurement of diffusivity: Calorimetric studies of Fe/Ni multilayer thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, JX; Barmak, K

2015-07-15

A calorimetric method for the measurement of diffusivity in thin film multilayers is introduced and applied to the Fe Ni system. Using this method, the diffusivity in [Fe (25 nm)/Ni (25 nm)](20) multilayer thin films is measured as 4 x 10(-3)exp(-1.6 +/- 0.1 eV/ k(B)T) cm(2)/s, respectively. The diffusion mechanism in the multilayers and its relevance to laboratory synthesis of L1(0) ordered FeNi are discussed. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Preparation of Carbon Nanotube/TiO2 Mesoporous Hybrid Photoanode with Iron Pyrite (FeS2) Thin Films Counter Electrodes for Dye-Sensitized Solar Cell

PubMed Central

Kilic, Bayram; Turkdogan, Sunay; Astam, Aykut; Ozer, Oguz Can; Asgin, Mansur; Cebeci, Hulya; Urk, Deniz; Mucur, Selin Pravadili

2016-01-01

Multi-walled carbon nanotube (MWCNT)/TiO2 mesoporous networks can be employed as a new alternative photoanode in dye-sensitized solar cells (DSSCs). By using the MWCNT/TiO2 mesoporous as photoanodes in DSSC, we demonstrate that the MWCNT/TiO2 mesoporous photoanode is promising alternative to standard FTO/TiO2 mesoporous based DSSC due to larger specific surface area and high electrochemical activity. We also show that iron pyrite (FeS2) thin films can be used as an efficient counter electrode (CE), an alternative to the conventional high cost Pt based CE. We are able to synthesis FeS2 nanostructures utilizing a very cheap and easy hydrothermal growth route. MWCNT/TiO2 mesoporous based DSSCs with FeS2 CE achieved a high solar conversion efficiency of 7.27% under 100 mW cm−2 (AM 1.5G 1-Sun) simulated solar irradiance which is considerably (slightly) higher than that of A-CNT/TiO2 mesoporous based DSSCs with Pt CE. Outstanding performance of the FeS2 CE makes it a very promising choice among the various CE materials used in the conventional DSSC and it is expected to be used more often to achieve higher photon-to-electron conversion efficiencies. PMID:27243374

Method for the manufacture of phase shifting masks for EUV lithography

DOEpatents

Stearns, Daniel G.; Sweeney, Donald W.; Mirkarimi, Paul B.; Barty, Anton

2006-04-04

A method for fabricating an EUV phase shift mask is provided that includes a substrate upon which is deposited a thin film multilayer coating that has a complex-valued reflectance. An absorber layer or a buffer layer is attached onto the thin film multilayer, and the thickness of the thin film multilayer coating is altered to introduce a direct modulation in the complex-valued reflectance to produce phase shifting features.

Epitaxial growth and magnetic properties of ultraviolet transparent Ga2O3/(Ga1-xFex)2O3 multilayer thin films.

PubMed

Guo, Daoyou; An, Yuehua; Cui, Wei; Zhi, Yusong; Zhao, Xiaolong; Lei, Ming; Li, Linghong; Li, Peigang; Wu, Zhenping; Tang, Weihua

2016-04-28

Multilayer thin films based on the ferromagnetic and ultraviolet transparent semiconductors may be interesting because their magnetic/electronic/photonic properties can be manipulated by the high energy photons. Herein, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films were obtained by alternating depositing of wide band gap Ga2O3 layer and Fe ultrathin layer due to inter diffusion between two layers at high temperature using the laser molecular beam epitaxy technique. The multilayer films exhibits a preferred growth orientation of crystal plane, and the crystal lattice expands as Fe replaces Ga site. Fe ions with a mixed valence of Fe(2+) and Fe(3+) are stratified distributed in the film and exhibit obvious agglomerated areas. The multilayer films only show a sharp absorption edge at about 250 nm, indicating a high transparency for ultraviolet light. What's more, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films also exhibits room temperature ferromagnetism deriving from the Fe doping Ga2O3.

Developing Multilayer Thin Film Strain Sensors With High Thermal Stability

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Gonzalez, Jose M., III

2006-01-01

A multilayer thin film strain sensor for large temperature range use is under development using a reactively-sputtered process. The sensor is capable of being fabricated in fine line widths utilizing the sacrificial-layer lift-off process that is used for micro-fabricated noble-metal sensors. Tantalum nitride films were optimized using reactive sputtering with an unbalanced magnetron source. A first approximation model of multilayer resistance and temperature coefficient of resistance was used to set the film thicknesses in the multilayer film sensor. Two multifunctional sensors were fabricated using multilayered films of tantalum nitride and palladium chromium, and tested for low temperature resistivity, TCR and strain response. The low temperature coefficient of resistance of the films will result in improved stability in thin film sensors for low to high temperature use.

Polyelectrolyte-mediated assembly of copper-phthalocyanine tetrasulfonate multilayers and the subsequent production of nanoparticulate copper oxide thin films.

PubMed

Chickneyan, Zarui Sara; Briseno, Alejandro L; Shi, Xiangyang; Han, Shubo; Huang, Jiaxing; Zhou, Feimeng

2004-07-01

An approach to producing films of nanometer-sized copper oxide particulates, based on polyelectrolyte-mediated assembly of the precursor, copper(II)phthalocyanine tetrasulfonate (CPTS), is described. Multilayered CPTS and polydiallyldimethylammonium chloride (PDADMAC) were alternately assembled on different planar substrates via the layer-by-layer (LbL) procedure. The growth of CPTS multilayers was monitored by UV-visible spectrometry and quartz crystal microbalance (QCM) measurements. Both the UV-visible spectra and the QCM data showed that a fixed amount of CPTS could be attached to the substrate surface for a given adsorption cycle. Cyclic voltammograms at the CPTS/PDADMAC-covered gold electrode exhibited a decrease in peak currents with the layer number, indicating that the permeability of CPTS multilayers on the electrodes had diminished. When these CPTS multilayered films were calcined at elevated temperatures, uniform thin films composed of nanoparticulate copper oxide could be produced. Ellipsometry showed that the thickness of copper oxide nanoparticulate films could be precisely tailored by varying the thickness of CPTS multilayer films. The morphology and roughness of CPTS multilayer and copper oxide thin films were characterized by atomic force microscopy. X-ray diffraction (XRD) measurements indicated that these thin films contained both CuO and Cu2O nanoparticles. The preparation of such copper oxide thin films with the use of metal complex precursors represents a new route for the synthesis of inorganic oxide films with a controlled thickness.

Template-mediated, Hierarchical Engineering of Ordered Mesoporous Films and Powders

NASA Astrophysics Data System (ADS)

Tian, Zheng

Hierarchical control over pore size, pore topology, and meso/mictrostructure as well as material morphology (e.g., powders, monoliths, thin films) is crucial for meeting diverse materials needs among applications spanning next generation catalysts, sensors, batteries, sorbents, etc. The overarching goal of this thesis is to establish fundamental mechanistic insight enabling new strategies for realizing such hierarchical textural control for carbon materials that is not currently achievable with sacrificial pore formation by 'one-pot' surfactant-based 'soft'-templating or multi-step inorganic 'hard-templating. While 'hard'-templating is often tacitly discounted based upon its perceived complexity, it offers potential for overcoming key 'soft'-templating challenges, including bolstering pore stability, accommodating a more versatile palette of replica precursors, realizing ordered/spanning porosity in the case of porous thin films, simplifying formation of bi-continuous pore topologies, and inducing microstructure control within porous replica materials. In this thesis, we establish strategies for hard-templating of hierarchically porous and structured carbon powders and tunable thin films by both multi-step hard-templating and a new 'one-pot' template-replica precursor co-assembly process. We first develop a nominal hard-templating technique to successfully prepare three-dimensionally ordered mesoporous (3DOm) and 3DOm-supported microporous carbon thin films by exploiting our ability to synthesize and assemble size-tunable silica nanoparticles into scalable, colloidal crystalline thin film templates of tunable mono- to multi-layer thickness. This robust thin film template accommodates liquid and/or vapor-phase infiltration, polymerization, and pyrolysis of various carbon sources without pore contraction and/or collapse upon template sacrifice. The result is robust, flexible 3DOm or 3DOm-supported ultra-thin microporous films that can be transferred by stamp techniques to various substrates for low-cost counter-electrodes in dye-sensitized solar cells, as we demonstrate, or as potential high-flux membranes for molecular separations. Inspired by 'one-pot' 'soft'-templating approaches, wherein the pore forming agent and replica precursor are co-assembled, we establish how 'hard'-templating can be carried out in an analogous fashion. Namely, we show how pre-formed silica nanoparticles can be co-assembled from aqueous solutions with a carbon source (glucose), leading to elucidation of a pseudo-phase behavior in which we identify an operating window for synthesis of hierarchically bi-continuous carbon films. Systematic study of the association of carbon precursors with the silica particles in combination with transient coating experiments reveals mechanistic insight into how silica-adsorbed carbon precursor modulates particle assembly and ultimately controls template particle d-spacing. We uncover a critical d-spacing defining the boundary between ordered and disordered mesoporosity within the resulting films. We ultimately extend this thin-film mechanistic insight to realize 'one'-pot, bi-continuous 3DOm carbon powders. Through a combination of X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and high-resolution transmission electron microscopy (HR-TEM), we elucidate novel synthesis-structure relations for template-mediated microstructuring of the 3DOm replica carbons. Attractive properties of the resulting bi-continuous porous carbons for applications, for example, as novel electrodes, include high surface areas, large mesopore volumes, and tunable graphitic content (i.e. >50%) and character. We specifically demonstrate their performance, in thin film form, as counter-electrodes in dye-sensitized solar cells. We also demonstrate how they can be exploited in powder form as high-performance supercapacitor electrodes exhibiting attractive retention and absolute capacitance. We conclude the thesis by demonstrating the versatility of both the thin-film and powder templating processes developed herein, for realizing ordered binary colloidal crystal templates and their bi-modal porous carbon replica films, expanding compositional diversity of the 'one-pot' thin film process beyond carbons to include an example of 3DOm ZrO2 films, and employing the hard-templating process as a strategy for realizing 3DOm carbon-supported nanocarbides.

Epitaxial growth and magnetic properties of ultraviolet transparent Ga2O3/(Ga1−xFex)2O3 multilayer thin films

PubMed Central

Guo, Daoyou; An, Yuehua; Cui, Wei; Zhi, Yusong; Zhao, Xiaolong; Lei, Ming; Li, Linghong; Li, Peigang; Wu, Zhenping; Tang, Weihua

2016-01-01

Multilayer thin films based on the ferromagnetic and ultraviolet transparent semiconductors may be interesting because their magnetic/electronic/photonic properties can be manipulated by the high energy photons. Herein, the Ga2O3/(Ga1−xFex)2O3 multilayer epitaxial thin films were obtained by alternating depositing of wide band gap Ga2O3 layer and Fe ultrathin layer due to inter diffusion between two layers at high temperature using the laser molecular beam epitaxy technique. The multilayer films exhibits a preferred growth orientation of crystal plane, and the crystal lattice expands as Fe replaces Ga site. Fe ions with a mixed valence of Fe2+ and Fe3+ are stratified distributed in the film and exhibit obvious agglomerated areas. The multilayer films only show a sharp absorption edge at about 250 nm, indicating a high transparency for ultraviolet light. What’s more, the Ga2O3/(Ga1−xFex)2O3 multilayer epitaxial thin films also exhibits room temperature ferromagnetism deriving from the Fe doping Ga2O3. PMID:27121446

Fabrication of ATO/Graphene Multi-layered Transparent Conducting Thin Films

NASA Astrophysics Data System (ADS)

Li, Na; Chen, Fei; Shen, Qiang; Wang, Chuanbin; Zhang, Lianmeng

2013-03-01

A novel transparent conducting oxide based on the ATO/graphene multi-layered thin films has been developed to satisfy the application of transparent conductive electrode in solar cells. The ATO thin films are prepared by pulsed laser deposition method with high quality, namely the sheet resistance of 49.5 Ω/sq and average transmittance of 81.9 %. The prepared graphene sheet is well reduced and shows atomically thin, spotty distributed appearance on the top of the ATO thin films. The XRD and optical micrographs are used to confirm the successfully preparation of the ATO/graphene multi-layered thin films. The Hall measurements and UV-Vis spectrophotometer are conducted to evaluate the sheet resistance and optical transmittance of the innovative structure. It is found that graphene can improve the electrical properties of the ATO thin films with little influence on the optical transmittance.

Soft Magnetic Multilayered Thin Films for HF Applications

NASA Astrophysics Data System (ADS)

Loizos, George; Giannopoulos, George; Serletis, Christos; Maity, Tuhin; Roy, Saibal; Lupu, Nicoleta; Kijima, Hanae; Yamaguchi, Masahiro; Niarchos, Dimitris

Multilayered thin films from various soft magnetic materials were successfully prepared by magnetron sputtering in Ar atmosphere. The magnetic properties and microstructure were investigated. It is found that the films show good soft magnetic properties: magnetic coercivity of 1-10 Oe and saturation magnetization higher than 1T. The initial permeability of the films is greater than 300 and flattens up to 600 MHz. The multilayer thin film properties in combination with their easy, fast and reproducible fabrication indicate that they are potential candidates for high frequency applications.

Patterning of magnetic thin films and multilayers using nanostructured tantalum gettering templates.

PubMed

Qiu, Wenlan; Chang, Long; Lee, Dahye; Dannangoda, Chamath; Martirosyan, Karen; Litvinov, Dmitri

2015-03-25

This work demonstrates that a nonmagnetic thin film of cobalt oxide (CoO) sandwiched between Ta seed and capping layers can be effectively reduced to a magnetic cobalt thin film by annealing at 200 °C, whereas CoO does not exhibit ferromagnetic properties at room temperature and is stable at up to ∼400 °C. The CoO reduction is attributed to the thermodynamically driven gettering of oxygen by tantalum, similar to the exothermic reduction-oxidation reaction observed in thermite systems. Similarly, annealing at 200 °C of a nonmagnetic [CoO/Pd]N multilayer thin film sandwiched between Ta seed and Ta capping layers results in the conversion into a magnetic [Co/Pd]N multilayer, a material with perpendicular magnetic anisotropy that is of interest for magnetic data storage applications. A nanopatterning approach is introduced where [CoO/Pd]N multilayers is locally reduced into [Co/Pd]N multilayers to achieve perpendicular magnetic anisotropy nanostructured array. This technique can potentially be adapted to nanoscale patterning of other systems for which thermodynamically favorable combination of oxide and gettering layers can be identified.

In-situ stress measurement of single and multilayer thin-films used in x-ray astronomy optics applications

NASA Astrophysics Data System (ADS)

Broadway, David M.; Ramsey, Brian D.; O'Dell, Stephen L.; Gurgew, Danielle

2017-09-01

We present in-situ stress measurement results for single and multilayer thin-films deposited by magnetron sputtering. In particular, we report on the influence of the material interfaces on the ensuing stress in both the transient and steady-state regimes of film growth. This behavior is used to determine the appropriate thicknesses of the constituent layers that will result in a net tensile stress in multilayers composed of various material combinations. These multilayers can then be used to compensate the compressive integrated stress in single and multilayer EUV and x-ray optical coatings. The use of multilayers to compensate the integrated stress might be advantageous because, unlike single layers of chromium, the roughness is not expected to increase with the total thickness of the multilayer. In this paper, we demonstrate the technique for W/Si and Mo/Si multilayers and discuss its application to other material combinations.

Bicontinuous mesoporous carbon thin films via an order-order transition.

PubMed

Deng, Guodong; Zhang, Yuanzhong; Ye, Changhuai; Qiang, Zhe; Stein, Gila E; Cavicchi, Kevin A; Vogt, Bryan D

2014-10-28

Bicontinuous mesoporous carbon films are fabricated by cooperative self-assembly of phenolic resin and amphiphilic triblock copolymer via an order-order transition from cylinders to gyroid. The film morphology is strongly influenced by the details of processing, including age of the resol, resol : template ratio, and the solvent vapor annealing process.

Europium-doped mesoporous titania thin films: rare-earth locations and emission fluctuations under illumination.

PubMed

Leroy, Celine Marie; Cardinal, Thierry; Jubera, Veronique; Treguer-Delapierre, Mona; Majimel, Jerome; Manaud, Jean Pierre; Backov, Renal; Boissière, Cedric; Grosso, David; Sanchez, Clement; Viana, Bruno; Pellé, Fabienne

2008-10-06

Herein, Eu(III)-doped 3D mesoscopically ordered arrays of mesoporous and nanocrystalline titania are prepared and studied. The rare-earth-doped titania thin films-synthesized via evaporation-induced self-assembly (EISA)-are characterized by using environmental ellipsoporosimetry, electronic microscopy (i.e. high-resolution scanning electron microscopy, HR-SEM, and transmission electron microscopy, HR-TEM), X-ray diffraction, and luminescence spectroscopy. Structural characterizations show that high europium-ion loadings can be incorporated into the titanium-dioxide walls without destroying the mesoporous arrangement. The luminescence properties of Eu(III) are investigated by using steady-state and time-resolved spectroscopy via excitation of the Eu(III) ions through the titania host. Using Eu(III) luminescence as a probe, the europium-ion sites can be addressed with at least two different environments within the mesoporous framework, namely, a nanocrystalline environment and a glasslike one. Emission fluctuations ((5)D(0)-->(7)F(2)) are observed upon continuous UV excitation in the host matrix. These fluctuations are attributed to charge trapping and appear to be strongly dependent on the amount of europium and the level of crystallinity.

Elaboration and properties of hierarchically structured optical thin films of MIL-101(Cr).

PubMed

Demessence, Aude; Horcajada, Patricia; Serre, Christian; Boissière, Cédric; Grosso, David; Sanchez, Clément; Férey, Gérard

2009-12-14

Stable nanoparticles dispersions of the porous hybrid MIL-101(Cr) allow dip-coating of high quality optical thin films with dual hierarchical porous structure. Moreover, for the first time, mechanical and sorption properties of mesoporous MOFs based thin films are evaluated.

Microstructure and thermochromic properties of VOX-WOX-VOX ceramic thin films

NASA Astrophysics Data System (ADS)

Khamseh, S.; Araghi, H.; Ghahari, M.; Faghihi Sani, M. A.

2016-03-01

W-doped VO2 films have been synthesized via oxygen annealing of V-W-V (vanadium-tungsten-vanadium) multilayered films. The effects of middle layer's thickness of V-W-V multilayered film on structure and properties of VOX-WOX-VOX ceramic thin films were investigated. The as-deposited V-W-V multilayered film showed amorphous-like structure when mixed structure of VO2 (M) and VO2 (B) was formed in VOX-WOX-VOX ceramic thin films. Tungsten content of VOX-WOX-VOX ceramic thin films increased with increasing middle layer's thickness. With increasing middle layer's thickness, room temperature square resistance ( R sq) of VOX-WOX-VOX ceramic thin films increased from 65 to 86 kΩ/sq. The VOX-WOX-VOX ceramic thin film with the thinnest middle layer showed significant SMT (semiconductor-metal transition) when SMT became negligible on increasing middle layer's thickness.

Hydrogen incorporation by plasma treatment gives mesoporous black TiO 2 thin films with visible photoelectrochemical water oxidation activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Islam, Syed Z.; Reed, Allen; Nagpure, Suraj

In this work, we use neutron reflectometry (NR) to investigate the roles of hydrogen in plasma treated hydrogen doped mesoporous black titania thin films in their visible light absorption and enhanced photoactivity for water oxidation. The cubic ordered mesoporous TiO 2 thin films are prepared by a surfactant-templated sol-gel method and are treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate that H 2 plasma treatment makes TiO 2 films black, with broad-spectrum enhancementmore » of visible light absorption, and XPS analysis shows peak for Ti 3+ state in treated films. The presence of hydrogen in black mesoporous titania (H-TiO 2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO 2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO 2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide the first direct evidence that the dramatic change in visible light absorbance of H-treated black TiO 2 is accompanied by significant hydrogen uptake and not just Ti 3+ generation or surface disordering.« less

Hydrogen incorporation by plasma treatment gives mesoporous black TiO 2 thin films with visible photoelectrochemical water oxidation activity

DOE PAGES

Islam, Syed Z.; Reed, Allen; Nagpure, Suraj; ...

2017-10-26

In this work, we use neutron reflectometry (NR) to investigate the roles of hydrogen in plasma treated hydrogen doped mesoporous black titania thin films in their visible light absorption and enhanced photoactivity for water oxidation. The cubic ordered mesoporous TiO 2 thin films are prepared by a surfactant-templated sol-gel method and are treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate that H 2 plasma treatment makes TiO 2 films black, with broad-spectrum enhancementmore » of visible light absorption, and XPS analysis shows peak for Ti 3+ state in treated films. The presence of hydrogen in black mesoporous titania (H-TiO 2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO 2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO 2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide the first direct evidence that the dramatic change in visible light absorbance of H-treated black TiO 2 is accompanied by significant hydrogen uptake and not just Ti 3+ generation or surface disordering.« less

Hydrogen incorporation by plasma treatment gives mesoporous black TiO 2 thin films with visible photoelectrochemical water oxidation activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Islam, Syed Z.; Reed, Allen; Nagpure, Suraj

2018-05-01

In this work, we use neutron reflectometry (NR) to investigate the roles of hydrogen in plasma treated hydrogen doped mesoporous black titania thin films in their visible light absorption and enhanced photoactivity for water oxidation. The cubic ordered mesoporous TiO2 thin films are prepared by a surfactant-templated sol-gel method and are treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate that H2 plasma treatment makes TiO2 films black, with broad-spectrum enhancement of visible lightmore » absorption, and XPS analysis shows peak for Ti3+ state in treated films. The presence of hydrogen in black mesoporous titania (H-TiO2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide the first direct evidence that the dramatic change in visible light absorbance of H-treated black TiO2 is accompanied by significant hydrogen uptake and not just Ti3+ generation or surface disordering.« less

Thin-Layer Polymer Wrapped Enzymes Encapsulated in Hierarchically Mesoporous Silica with High Activity and Enhanced Stability

NASA Astrophysics Data System (ADS)

Zhang, Fang; Wang, Meitao; Liang, Chao; Jiang, Huangyong; Shen, Jian; Li, Hexing

2014-03-01

A novel soft-hard cooperative approach was developed to synthesize bioactive mesoporous composite by pre-wrapping Penicillin G amidase with poly(acrylaimde) nanogel skin and subsequently incorporating such Penicillin G amidase nanocapsules into hierarchically mesoporous silica. The as-received bioactive mesoporous composite exhibited comparable activity and extraordinarily high stability in comparison with native Penicillin G amidase and could be used repetitively in the water-medium hydrolysis of penicillin G potassium salt. Furthermore, this strategy could be extended to the synthesis of multifunctional bioactive mesoporous composite by simultaneously introducing glucose oxidase nanocapsules and horseradish peroxidase nanocapsules into hierarchically mesoporous silica, which demonstrated a synergic effect in one-pot tandem oxidation reaction. Improvements in the catalytic performances were attributed to the combinational unique structure from soft polymer skin and hard inorganic mesoporous silica shell, which cooperatively helped enzyme molecules to retain their appropriate geometry and simultaneously decreased the enzyme-support negative interaction and mass transfer limitation under heterogeneous conditions.

Chemical vapor deposition of mesoporous graphene nanoballs for supercapacitor.

PubMed

Lee, Jung-Soo; Kim, Sun-I; Yoon, Jong-Chul; Jang, Ji-Hyun

2013-07-23

A mass-producible mesoporous graphene nanoball (MGB) was fabricated via a precursor-assisted chemical vapor deposition (CVD) technique for supercapacitor application. Polystyrene balls and reduced iron created under high temperature and a hydrogen gas environment provide a solid carbon source and a catalyst for graphene growth during the precursor-assisted CVD process, respectively. Carboxylic acid and sulfonic acid functionalization of the polystyrene ball facilitates homogeneous dispersion of the hydrophobic polymer template in the metal precursor solution, thus, resulting in a MGB with a uniform number of graphene layers. The MGB is shown to have a specific surface area of 508 m(2)/g and is mesoporous with a mean mesopore diameter of 4.27 nm. Mesopores are generated by the removal of agglomerated iron domains, permeating down through the soft polystyrene spheres and providing the surface for subsequent graphene growth during the heating process in a hydrogen environment. This technique requires only drop-casting of the precursor/polystyrene solution, allowing for mass-production of multilayer MGBs. The supercapacitor fabricated by the use of the MGB as an electrode demonstrates a specific capacitance of 206 F/g and more than 96% retention of capacitance after 10,000 cycles. The outstanding characteristics of the MGB as an electrode for supercapacitors verify the strong potential for use in energy-related areas.

Synthesis of a large-sized mesoporous phosphosilicate thin film through evaporation-induced polymeric micelle assembly.

PubMed

Li, Yunqi; Bastakoti, Bishnu Prasad; Imura, Masataka; Suzuki, Norihiro; Jiang, Xiangfen; Ohki, Shinobu; Deguchi, Kenzo; Suzuki, Madoka; Arai, Satoshi; Yamauchi, Yusuke

2015-01-01

A triblock copolymer, poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) was used as a soft template to synthesize large-sized mesoporous phosphosilicate thin films. The kinetically frozen PS core stabilizes the micelles. The strong interaction of the inorganic precursors with the P2VP shell enables the fabrication of highly robust walls of phosphosilicate and the PEO helps orderly packing of the micelles during solvent evaporation. The molar ratio of phosphoric acid and tetraethyl orthosilicate is crucial to achieve the final mesostructure. The insertion of phosphorus species into the siloxane network is studied by (29) Si and (31) P MAS NMR spectra. The mesoporous phosphosilicate films exhibit steady cell adhesion properties and show great promise as excellent materials in bone-growth engineering applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface engineering on mesoporous silica chips for enriching low molecular weight phosphorylated proteins

NASA Astrophysics Data System (ADS)

Hu, Ye; Peng, Yang; Lin, Kevin; Shen, Haifa; Brousseau, Louis C., III; Sakamoto, Jason; Sun, Tong; Ferrari, Mauro

2011-02-01

Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous silica thin films with precisely engineered pore sizes that sterically select for molecular size combined with chemically selective surface modifications (i.e. Ga3+, Ti4+ and Zr4+) that target phosphoroproteins. These materials provide high reproducibility (CV = 18%) and increase the stability of the captured proteins by excluding degrading enzymes, such as trypsin. The chemical and physical properties of the composite mesoporous thin films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and ellipsometry. Using mass spectroscopy and biostatistics analysis, the enrichment efficiency of different metal ions immobilized on mesoporous silica chips was investigated. The novel technology reported provides a platform capable of efficiently profiling the serum proteome for biomarker discovery, forensic sampling, and routine diagnostic applications.Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous silica thin films with precisely engineered pore sizes that sterically select for molecular size combined with chemically selective surface modifications (i.e. Ga3+, Ti4+ and Zr4+) that target phosphoroproteins. These materials provide high reproducibility (CV = 18%) and increase the stability of the captured proteins by excluding degrading enzymes, such as trypsin. The chemical and physical properties of the composite mesoporous thin films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and ellipsometry. Using mass spectroscopy and biostatistics analysis, the enrichment efficiency of different metal ions immobilized on mesoporous silica chips was investigated. The novel technology reported provides a platform capable of efficiently profiling the serum proteome for biomarker discovery, forensic sampling, and routine diagnostic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c0nr00720j

Multilayer thin film design as far ultraviolet quarterwave retarders

NASA Technical Reports Server (NTRS)

Kim, Jongmin; Zukic, Muamer; Torr, Douglas T.; Wilson, Michele M.

1993-01-01

At short wavelengths, such as FUV, transparent, optically active materials are scarce. Reflection phase retardation by a multilayer thin film can be a good alternative in this wavelength region. We design a multilayer quarterwave retarder by calculating the electric fields at each boundary in the multilayer thin film. Using this method, we achieve designs of FUV multilayers which provide high, matched reflectances for both s- and p-polarization states, and at the same time a phase difference between these two states of nearly 90 deg. For example, a quarterwave retarder designed at the Lyman-alpha line (121.6 nm) has 81.05 percent reflectance for the s-polarization and 81.04 percent for the p-polarization state. The phase difference between these two polarization states is 90.07 deg. For convenience the retarders are designed for 45 deg angle of incidence, but our design approach can be used for any other angle of incidence. Aluminum and MgF2 are used as film materials and an opaque thick film of aluminum as the substrate.

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

PubMed

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

2013-06-28

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

Electro-Caloric Properties of BT/PZT Multilayer Thin Films Prepared by Sol-Gel Method.

PubMed

Kwon, Min-Su; Lee, Sung-Gap; Kim, Kyeong-Min

2018-09-01

In this study, Barium Titanate (BT)/Lead Zirconate Titanate (PZT) multilayer thin films were fabricated by the spin-coating method on Pt (200 nm)/Ti (10 nm) SiO2 (100 nm)/P-Si (100) substrates using BaTiO3 and Pb(Zr0.90Ti0.10)O3 metal alkoxide solutions. The coating and heating procedure was repeated several times to form the multilayer thin films. All of BT/PZT multilayer thin films show X-ray diffraction patterns typical to a polycrystalline perovskite structure and a uniform and void free grain microstructure. The thickness of the BT and PZT film by one-cycle of drying/sintering was approximately 50 nm and all of the films consisted of fine grains with a flat surface morphology. The electrocaloric properties of BT/PZT thin films were investigated by indirect estimation. The results showed that the temperature change ΔT can be calculated as a function of temperature using Maxwell's relation; the temperature change reaches a maximum value of ~1.85 °C at 135 °C under an applied electric field of 260 kV/cm.

Versatility of Evaporation-Induced Self-Assembly (EISA) Method for Preparation of Mesoporous TiO2 for Energy and Environmental Applications

PubMed Central

Mahoney, Luther; Koodali, Ranjit T.

2014-01-01

Evaporation-Induced Self-Assembly (EISA) method for the preparation of mesoporous titanium dioxide materials is reviewed. The versatility of EISA method for the rapid and facile synthesis of TiO2 thin films and powders is highlighted. Non-ionic surfactants such as Pluronic P123, F127 and cationic surfactants such as cetyltrimethylammonium bromide have been extensively employed for the preparation of mesoporous TiO2. In particular, EISA method allows for fabrication of highly uniform, robust, crack-free films with controllable thickness. Eleven characterization techniques for elucidating the structure of the EISA prepared mesoporous TiO2 are discussed in this paper. These many characterization methods provide a holistic picture of the structure of mesoporous TiO2. Mesoporous titanium dioxide materials have been employed in several applications that include Dye Sensitized Solar Cells (DSSCs), photocatalytic degradation of organics and splitting of water, and batteries. PMID:28788590

Thermosensitive block copolymer [(PNIPAM)-b-(Glycine)] thin film as protective layer for drug loaded mesoporous silica nanoparticles

NASA Astrophysics Data System (ADS)

Amgoth, Chander; Joshi, Suman

2017-10-01

Synthesis and characterization of [(PNIPAM)-b-(Gly)] and mesoporous silica nanoparticles (MP-SiO2 NPs) were carried out separately and used to develop [(PNIPAM)-b-(Gly)]-(MP-SiO2 NPs). The synthesized MP-SiO2 NPs were meso porous in nature. The size of SiO2 NPs is in the range of ~180-250 nm (in diameter) with an average pore size of 2.8 nm within the particles. Interestingly, these mesoporous SiO2 NPs were loaded with anticancer drug (ITM-imatinib mesylate) fallow by the incubation for 24 h at RT. However, ITM loaded MP-SiO2 NPs were capped or covered with synthesized [(PNIPAM)-b-(Gly)] thin film. Here, thin film acts as protective layer for drug loaded MP-SiO2 NPs, with that leakage of drug molecules throughout its transport pathway can be avoided. Significantly, thermosensitive [(PNIPAM)-b-(Gly)] polymer thin film depletes at body temperature (~37 °C) and drug molecules come out from the pores of SiO2 NPs. However, developed [(PNIPAM)-b-(Gly)]-(MP-SiO2 NPs) is compatible and used for cell inhibition studies. After 24 h treatment, drug ITM released from [(PNIPAM)-b-(Gly)]-(MP-SiO2 NPs) shows significant (>90%) inhibition on leukemia blood cancer (K562) cells.

Enhancement of the electrical characteristics of thin-film transistors with indium-zinc-tin oxide/Ag/indium-zinc-tin oxide multilayer electrodes

NASA Astrophysics Data System (ADS)

Oh, Dohyun; Yun, Dong Yeol; Cho, Woon-Jo; Kim, Tae Whan

2014-08-01

Transparent indium-zinc-tin oxide (IZTO)-based thin-film transistors (TFTs) with IZTO/Ag/IZTO multilayer electrodes were fabricated on glass substrates using a tilted dual-target radio-frequency magnetron sputtering system. The IZTO TFTs with IZTO/Ag/IZTO multilayer electrodes exhibited a high optical transmittance in a visible region. The threshold voltage, the mobility, and the on/off-current ratio of the TFTs with IZTO/Ag/IZTO multilayer electrodes were enhanced in comparison with those of the TFTs with ITO electrodes. The source/drain contact resistance of the IZTO TFTs with IZTO/Ag/IZTO multilayer electrodes was smaller than that of the IZTO TFTs with ITO electrodes, resulting in enhancement of their electrical characteristics.

Multilayer polymer dielectric films for hollow glass waveguides

NASA Astrophysics Data System (ADS)

Kendall, Wesley; Harrington, James A.

2018-02-01

Hollow glass waveguides (HGWs) have been extensively investigated for the transmission of broadband, high-power radiation, particularly in the mid-infrared. One area of particular interest is the deposition of dielectric thin films within the hollow core of the HGW in order to reduce the losses at desired wavelengths. By implementing a thin film multilayer structure with high index mismatch between adjacent films, it is possible to dramatically improve the losses of the waveguides due to the thin film interference effect. Existing multilayer film research has utilized heavy metal halides, which although provide considerable index contrast, are toxic and unsuitable for clinical applications in which they are often used. Polymer dielectric thin films provide desirable optical properties for HGWs but are hindered by solvent compatibility in the deposition procedure. This work demonstrates implementation of a polymer multilayer dielectric thin film stack within a HGW, using ChemoursTM Teflon AF (n = 1.29) as the low-index material and polystyrene (n = 1.59) as the high-index material. These two polymers were deposited using liquid phase techniques within a HGW; the absorption spectra of waveguide as each layer was deposited on was analyzed in the mid-IR with an FTIR, and straight and bending losses were measured on a CO2 laser. Appreciable losses were realized with the addition of the second polymer film and the interference bands red-shifted with the second layer, suggesting the successful creation of the multilayer structure.

One-Pot Fabrication of Antireflective/Antibacterial Dual-Function Ag NP-Containing Mesoporous Silica Thin Films.

PubMed

Wang, Kaikai; He, Junhui

2018-04-04

Thin films that integrate antireflective and antibacterial dual functions are not only scientifically interesting but also highly desired in many practical applications. Unfortunately, very few studies have been devoted to the preparation of thin films with both antireflective and antibacterial properties. In this study, mesoporous silica (MSiO 2 ) thin films with uniformly dispersed Ag nanoparticles (Ag NPs) were prepared through a one-pot process, which simultaneously shows high transmittance, excellent antibacterial activity, and mechanical robustness. The optimal thin-film-coated glass substrate demonstrates a maximum transmittance of 98.8% and an average transmittance of 97.1%, respectively, in the spectral range of 400-800 nm. The growth and multiplication of typical bacteria, Escherichia coli ( E. coli), were effectively inhibited on the coated glass. Pencil hardness test, tape adhesion test, and sponge washing test showed favorable mechanical robustness with 5H pencil hardness, 5A grade adhesion, and functional durability of the coating, which promises great potential for applications in various touch screens, windows for hygiene environments, and optical apparatuses for medical uses such as endoscope, and so on.

Facile solvothermal synthesis of NaTi2(PO4)3/C porous plates as electrode materials for high-performance sodium ion batteries

NASA Astrophysics Data System (ADS)

Huang, Zhifeng; Liu, Li; Yi, Lingguang; Xiao, Wei; Li, Min; Zhou, Qian; Guo, Guoxiong; Chen, Xiaoying; Shu, Hongbo; Yang, Xiukang; Wang, Xianyou

2016-09-01

NaTi2(PO4)3/C porous plates have been successfully synthesized via solvothermal approach with ammonia as inductive agent combined in-situ carbon coating. It reveals that the inductive agent plays a critical role in morphology-controllable fabrication. The morphology, structure, and electrochemical properties of NaTi2(PO4)3/C composites with multilayered plates, single-layered plate, porous multilayered plates all have been investigated, which are prepared by using urea, triethylamine, and ammonia, respectively. Among these samples, NaTi2(PO4)3/C porous multilayered plates with ammonia addition exhibit the best electrochemical properties due to their unique mesoporous structure. NaTi2(PO4)3/C porous multilayered plates deliver an initial specific capacity of 125 and 110 mAh g-1 at 0.1 and 1 C, respectively. Furthermore, NaTi2(PO4)3/C porous multilayered plates show a good rate capability, whose capacity and corresponding capacity retention reach 85 mAh g-1 and 82.4%, respectively, after 120 cycles under the high rate of 10 C. The excellent results indicate that the NaTi2(PO4)3/C porous multilayered plates are a promising electrode candidate for sodium ion battery.

Free-standing mesoporous carbon thin films with highly ordered pore architectures for nanodevices.

PubMed

Feng, Dan; Lv, Yingying; Wu, Zhangxiong; Dou, Yuqian; Han, Lu; Sun, Zhenkun; Xia, Yongyao; Zheng, Gengfeng; Zhao, Dongyuan

2011-09-28

We report for the first time the synthesis of free-standing mesoporous carbon films with highly ordered pore architecture by a simple coating-etching approach, which have an intact morphology with variable sizes as large as several square centimeters and a controllable thickness of 90 nm to ∼3 μm. The mesoporous carbon films were first synthesized by coating a resol precursors/Pluronic copolymer solution on a preoxidized silicon wafer and forming highly ordered polymeric mesostructures based on organic-organic self-assembly, followed by carbonizing at 600 °C and finally etching of the native oxide layer between the carbon film and the silicon substrate. The mesostructure of this free-standing carbon film is confirmed to be an ordered face-centered orthorhombic Fmmm structure, distorted from the (110) oriented body-centered cubic Im3̅m symmetry. The mesoporosity of the carbon films has been evaluated by nitrogen sorption, which shows a high specific BET surface area of 700 m(2)/g and large uniform mesopores of ∼4.3 nm. Both mesostructures and pore sizes can be tuned by changing the block copolymer templates or the ratio of resol to template. These free-standing mesoporous carbon films with cracking-free uniform morphology can be transferred or bent on different surfaces, especially with the aid of the soft polymer layer transfer technique, thus allowing for a variety of potential applications in electrochemistry and biomolecule separation. As a proof of concept, an electrochemical supercapacitor device directly made by the mesoporous carbon thin films shows a capacitance of 136 F/g at 0.5 A/g. Moreover, a nanofilter based on the carbon films has shown an excellent size-selective filtration of cytochrome c and bovine serum albumin.

Interplay between current driven ferromagnetism in charge ordered antiferromagnetic Pr0.5Ca0.5MnO3 and superconducting YBa2Cu3O7-δ thin film multilayer

NASA Astrophysics Data System (ADS)

Baisnab, Dipak Kumar; Sardar, Manas; Amaladass, E. P.; Vaidhyanathan, L. S.; Baskaran, R.

2018-07-01

Thin film multilayer heterostructure of alternate YBa2Cu3O7-δ (YBCO) and Pr0.5Ca0.5MnO3 (PCMO) with thickness of each layer ∼60 nm has been deposited on (100) oriented SrTiO3 substrate by Pulsed Laser Deposition technique. A half portion of the base YBCO layer was masked in situ using mechanical shadow mask and in the remaining half portion, five alternate layers of PCMO and YBCO thin films were deposited. Magnetoresistance measurements were carried out under externally applied magnetic field and injection current. A noticeable damped oscillation of the superconducting transition temperature (TC) of this multilayer with respect to magnetic field is seen. Curiously, the field at which the first minimum in TC occurs, decreases as an injection current is driven perpendicular/parallel to the multilayers. Both these phenomena indicate that ferromagnetic correlation can be induced in antiferromagnetic PCMO thin films by (1) external magnetic field, or (2) injection current. While (1) is well researched, our study indicates that ferromagnetism can be induced by small amount of current in PCMO thin films. This unusual behavior points towards the strongly correlated nature of electrons in PCMO.

Recent progress in high-mobility thin-film transistors based on multilayer 2D materials

NASA Astrophysics Data System (ADS)

Hong, Young Ki; Liu, Na; Yin, Demin; Hong, Seongin; Kim, Dong Hak; Kim, Sunkook; Choi, Woong; Yoon, Youngki

2017-04-01

Two-dimensional (2D) layered semiconductors are emerging as promising candidates for next-generation thin-film electronics because of their high mobility, relatively large bandgap, low-power switching, and the availability of large-area growth methods. Thin-film transistors (TFTs) based on multilayer transition metal dichalcogenides or black phosphorus offer unique opportunities for next-generation electronic and optoelectronic devices. Here, we review recent progress in high-mobility transistors based on multilayer 2D semiconductors. We describe the theoretical background on characterizing methods of TFT performance and material properties, followed by their applications in flexible, transparent, and optoelectronic devices. Finally, we highlight some of the methods used in metal-semiconductor contacts, hybrid structures, heterostructures, and chemical doping to improve device performance.

Structural and morphological properties of mesoporous carbon coated molybdenum oxide films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dayal, Saurabh, E-mail: saurabhdayal153@gmail.com; Kumar, C. Sasi, E-mail: csasimv@gmail.com

2016-05-06

In the present study, we report the structural and morphological properties of mesoporous carbon coated molybdenum oxide films. The deposition of films was carried out in a two-step process, the first step involves deposition of molybdenum and carbon bilayer thin films using DC magnetron sputtering. In the second step the sample was ex-situ annealed in a muffle furnace at different temperatures (400°C to 600°C) and air cooled in the ambient atmosphere. The formation of the meso-porous carbon clusters on molybdenum oxide during the cooling step was investigated using FESEM and AFM techniques. The structural details were explored using XRD. Themore » meso-porous carbon were found growing over molybdenum oxide layer as a result of segregation phenomena.« less

Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers

NASA Astrophysics Data System (ADS)

Best, James P.; Michler, Johann; Liu, Jianxi; Wang, Zhengbang; Tsotsalas, Manuel; Maeder, Xavier; Röse, Silvana; Oberst, Vanessa; Liu, Jinxuan; Walheim, Stefan; Gliemann, Hartmut; Weidler, Peter G.; Redel, Engelbert; Wöll, Christof

2015-09-01

Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth method. Control over respective fabrication processes allowed for tuning of the thickness of the thin film systems with a high degree of precision. It was found that the mechanical indentation of such thin films is significantly affected by the substrate properties; however, elastic parameters were able to be decoupled for constituent thin-film materials (EITO ≈ 96.7 GPa, EHKUST-1 ≈ 22.0 GPa). For indentation of multilayer stacks, it was found that as the layer thicknesses were increased, while holding the relative thickness of ITO and HKUST-1 constant, the resistance to deformation was significantly altered. Such an observation is likely due to small, albeit significant, changes in film texture, interfacial roughness, size effects, and controlling deformation mechanism as a result of increasing material deposition during processing. Such effects may have consequences regarding the rational mechanical design and utilization of MOF-based hybrid thin-film devices.

In Situ Growth of Mesoporous Silica with Drugs on Titanium Surface and Its Biomedical Applications.

PubMed

Wan, Mimi; Zhang, Jin; Wang, Qi; Zhan, Shuyue; Chen, Xudong; Mao, Chun; Liu, Yuhong; Shen, Jian

2017-06-07

Mesoporous silica has been developed for the modification of titanium surfaces that are used as implant materials. Yet, the traditional modification methods failed to effectively construct mesoporous silica on the titanium surface evenly and firmly, in which the interaction between mesoporous silica and titanium was mainly physical. Here, in situ growth of mesoporous silica on a titanium surface was performed using a simple evaporation-induced self-assembly strategy. Meantime, in situ introduction of drugs (heparin and vancomycin) to mesoporous silica was also adopted to improve the drug-loading amount. Both the above-mentioned processes were completed at the same time. Transmission electron microscopy, N 2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle measurements were used to characterize the structure of the mesoporous silica film. Results indicated that the mesoporous silica film that in situ grew on the titanium surface was smooth, thin, transparent, and stable. Cytotoxicity, proliferation performance of osteoblast cells, and in vitro and in vivo studies of the antibacterial activity of the coating were tested. This is the first study to modify the titanium surface by the in situ growth of a mesoporous silica coating with two kinds of drugs. The stability of the mesoporous silica coating can be attributed to the chemical bonding between dopamine and silicon hydroxyl of the mesoporous silica coating, and the smooth surface of mesoporous silica is a result of the method of in situ growth. The large amount of drug-loading also could be ascribed to the in situ introduction of drugs during the synthetic process. The strategy proposed in this work will bring more possibilities for the preparation of advanced functional materials based on the combination of mesoporous structure and metallic materials.

ZrO2 Layer Thickness Dependent Electrical and Dielectric Properties of BST/ZrO2/BST Multilayer Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahoo, S. K.; Misra, D.; Agrawal, D. C.

2011-01-01

Recently, high K materials play an important role in microelectronic devices such as capacitors, memory devices, and microwave devices. Now a days ferroelectric barium strontium titanate [Ba{sub x}Sr{sub 1-x}TiO{sub 3}, (BST)] thin film is being actively investigated for applications in dynamic random access memories (DRAM), field effect transistor (FET), and tunable devices because of its properties such as high dielectric constant, low leakage current, low dielectric loss, and high dielectric breakdown strength. Several approaches have been used to optimize the dielectric and electrical properties of BST thin films such as doping, graded compositions, and multilayer structures. We have found thatmore » inserting a ZrO{sub 2} layer in between two BST layers results in a significant reduction in dielectric constant, loss tangent, and leakage current in the multilayer thin films. Also it is shown that the properties of multilayer structure are found to depend strongly on the sublayer thicknesses. In this work the effect of ZrO{sub 2} layer thickness on the dielectric, ferroelectric as well as electrical properties of BST/ZrO{sub 2}/BST multilayer structure is studied. The multilayer Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3}/ZrO{sub 2}/Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} film is deposited by a sol-gel process on the platinized Si substrate. The thickness of the middle ZrO{sub 2} layer is varied while keeping the top and bottom BST layer thickness as fixed. It is observed that the dielectric constant, dielectric loss tangent, and leakage current of the multilayer films reduce with the increase of ZrO{sub 2} layer thickness and hence suitable for memory device applications. The ferroelectric properties of the multilayer film also decrease with the ZrO{sub 2} layer thickness.« less

Fabrication and improved photoelectrochemical properties of a transferred GaN-based thin film with InGaN/GaN layers.

PubMed

Cao, Dezhong; Xiao, Hongdi; Gao, Qingxue; Yang, Xiaokun; Luan, Caina; Mao, Hongzhi; Liu, Jianqiang; Liu, Xiangdong

2017-08-17

Herein, a lift-off mesoporous GaN-based thin film, which consisted of a strong phase-separated InGaN/GaN layer and an n-GaN layer, was fabricated via an electrochemical etching method in a hydrofluoric acid (HF) solution for the first time and then transferred onto quartz or n-Si substrates, acting as photoanodes during photoelectrochemical (PEC) water splitting in a 1 M NaCl aqueous solution. Compared to the as-grown GaN-based film, the transferred GaN-based thin films possess higher and blue-shifted light emission, presumably resulting from an increase in the surface area and stress relaxation in the InGaN/GaN layer embedded on the mesoporous n-GaN. The properties such as (i) high photoconversion efficiency, (ii) low turn-on voltage (-0.79 V versus Ag/AgCl), and (iii) outstanding stability enable the transferred films to have excellent PEC water splitting ability. Furthermore, as compared to the film transferred onto the quartz substrate, the film transferred onto the n-Si substrate exhibits higher photoconversion efficiency (2.99% at -0.10 V) due to holes (h + ) in the mesoporous n-GaN layer that originate from the n-Si substrate.

Facile synthesis of hierarchical mesoporous weirds-like morphological MnO2 thin films on carbon cloth for high performance supercapacitor application.

PubMed

Shinde, Pragati A; Lokhande, Vaibhav C; Ji, Taeksoo; Lokhande, Chandrakant D

2017-07-15

The mesoporous nanostructured metal oxides have a lot of capabilities to upsurge the energy storing capacity of the supercapacitor. In present work, different nanostructured morphologies of MnO 2 have been successfully fabricated on flexible carbon cloth by simple but capable hydrothermal method at different deposition temperatures. The deposition temperature has strong influence on reaction kinetics, which subsequently alters the morphology and electrochemical performance. Among different nanostructured MnO 2 thin films, the mesoporous weirds composed thin film obtained at temperature of 453K exhibits excellent physical and electrochemical features for supercapacitor application. The weirds composed MnO 2 thin film exhibits specific surface area of 109m 2 g -1 , high specific capacitance of 595Fg -1 with areal capacitance of 4.16Fcm -2 at a scan rate of 5mVs -1 and high specific energy of 56.32Whkg -1 . In addition to this, MnO 2 weirds attain capacity retention of 87 % over 2000 CV cycles, representing better cycling stability. The enhanced electrochemical performance could be ascribed to direct growth of highly porous MnO 2 weirds on carbon cloth which provide more pathways for easy diffusion of electrolyte into the interior of electroactive material. The as-fabricated electrode with improved performance could be ascribed as a potential electrode material for energy storage devices. Copyright © 2017 Elsevier Inc. All rights reserved.

Mo/Si and Mo/Be multilayer thin films on Zerodur substrates for extreme-ultraviolet lithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mirkarimi, Paul B.; Bajt, Sasa; Wall, Mark A.

2000-04-01

Multilayer-coated Zerodur optics are expected to play a pivotal role in an extreme-ultraviolet (EUV) lithography tool. Zerodur is a multiphase, multicomponent material that is a much more complicated substrate than commonly used single-crystal Si or fused-silica substrates. We investigate the effect of Zerodur substrates on the performance of high-EUV reflectance Mo/Si and Mo/Be multilayer thin films. For Mo/Si the EUV reflectance had a nearly linear dependence on substrate roughness for roughness values of 0.06-0.36 nm rms, and the FWHM of the reflectance curves (spectral bandwidth) was essentially constant over this range. For Mo/Be the EUV reflectance was observed to decreasemore » more steeply than Mo/Si for roughness values greater than approximately 0.2-0.3 nm. Little difference was observed in the EUV reflectivity of multilayer thin films deposited on different substrates as long as the substrate roughness values were similar. (c) 2000 Optical Society of America.« less

Mo/Si and Mo/Be multilayer thin films on Zerodur substrates for extreme-ultraviolet lithography.

PubMed

Mirkarimi, P B; Bajt, S; Wall, M A

2000-04-01

Multilayer-coated Zerodur optics are expected to play a pivotal role in an extreme-ultraviolet (EUV) lithography tool. Zerodur is a multiphase, multicomponent material that is a much more complicated substrate than commonly used single-crystal Si or fused-silica substrates. We investigate the effect of Zerodur substrates on the performance of high-EUV reflectance Mo/Si and Mo/Be multilayer thin films. For Mo/Si the EUV reflectance had a nearly linear dependence on substrate roughness for roughness values of 0.06-0.36 nm rms, and the FWHM of the reflectance curves (spectral bandwidth) was essentially constant over this range. For Mo/Be the EUV reflectance was observed to decrease more steeply than Mo/Si for roughness values greater than approximately 0.2-0.3 nm. Little difference was observed in the EUV reflectivity of multilayer thin films deposited on different substrates as long as the substrate roughness values were similar.

In-situ aging microwave heating synthesis of LTA zeolite layer on mesoporous TiO2 coated porous alumina support

NASA Astrophysics Data System (ADS)

Baig, Mirza A.; Patel, Faheemuddin; Alhooshani, Khalid; Muraza, Oki; Wang, Evelyn N.; Laoui, Tahar

2015-12-01

LTA zeolite layer was successfully grown on a superhydrophilic mesoporous titania layer coated onto porous α-alumina substrate. Mesoporous titania layer was formed as an intermediate bridge in the pore size variation between the macroporous α-alumina support and micro-porous LTA zeolite layer. In-situ aging microwave heating synthesis method was utilized to deposit the LTA zeolite layer. Mesoporous titania layer was pre-treated with UV photons and this was observed to have played a major role in improving the surface hydrophilicity of the substrate leading to formation of increased number of Ti-OH groups on the surface. This increase in Ti-OH groups enhanced the interaction between the synthesis gel and the substrate leading to strong attachment of the amorphous gel on the substrate, thus enhancing coverage of the LTA zeolite layer to almost the entire surface of the 1-inch (25.4 mm) diameter membrane. LTA zeolite layer was developed via in-situ aged under microwave irradiation to study the effect of synthesis parameters such as in-situ aging time and synthesis time on the formation of the LTA zeolite layer. Optimized process parameters resulted in the formation of crack-free porous zeolite layer yielding a zeolite-titania-alumina multi-layer membrane with a gradient in porosity.

Chiral magnetic conductivity and surface states of Weyl semimetals in topological insulator ultra-thin film multilayer.

PubMed

Owerre, S A

2016-06-15

We investigate an ultra-thin film of topological insulator (TI) multilayer as a model for a three-dimensional (3D) Weyl semimetal. We introduce tunneling parameters t S, [Formula: see text], and t D, where the former two parameters couple layers of the same thin film at small and large momenta, and the latter parameter couples neighbouring thin film layers along the z-direction. The Chern number is computed in each topological phase of the system and we find that for [Formula: see text], the tunneling parameter [Formula: see text] changes from positive to negative as the system transits from Weyl semi-metallic phase to insulating phases. We further study the chiral magnetic effect (CME) of the system in the presence of a time dependent magnetic field. We compute the low-temperature dependence of the chiral magnetic conductivity and show that it captures three distinct phases of the system separated by plateaus. Furthermore, we propose and study a 3D lattice model of Porphyrin thin film, an organic material known to support topological Frenkel exciton edge states. We show that this model exhibits a 3D Weyl semi-metallic phase and also supports a 2D Weyl semi-metallic phase. We further show that this model recovers that of 3D Weyl semimetal in topological insulator thin film multilayer. Thus, paving the way for simulating a 3D Weyl semimetal in topological insulator thin film multilayer. We obtain the surface states (Fermi arcs) in the 3D model and the chiral edge states in the 2D model and analyze their topological properties.

High conductivity and transparent aluminum-based multi-layer source/drain electrodes for thin film transistors

NASA Astrophysics Data System (ADS)

Yao, Rihui; Zhang, Hongke; Fang, Zhiqiang; Ning, Honglong; Zheng, Zeke; Li, Xiaoqing; Zhang, Xiaochen; Cai, Wei; Lu, Xubing; Peng, Junbiao

2018-02-01

In this study, high conductivity and transparent multi-layer (AZO/Al/AZO-/Al/AZO) source/drain (S/D) electrodes for thin film transistors were fabricated via conventional physical vapor deposition approaches, without toxic elements or further thermal annealing process. The 68 nm-thick multi-layer films with excellent optical properties (transparency: 82.64%), good electrical properties (resistivity: 6.64  ×  10-5 Ω m, work function: 3.95 eV), and superior surface roughness (R q   =  0.757 nm with scanning area of 5  ×  5 µm2) were fabricated as the S/D electrodes. Significantly, comprehensive performances of AZO films are enhanced by the insertion of ultra-thin Al layers. The optimal transparent TFT with this multi-layer S/D electrodes exhibited a decent electrical performance with a saturation mobility (µ sat) of 3.2 cm2 V-1 s-1, an I on/I off ratio of 1.59  ×  106, a subthreshold swing of 1.05 V/decade. The contact resistance of AZO/Al/AZO/Al/AZO multi-layer electrodes is as low as 0.29 MΩ. Moreover, the average visible light transmittance of the unpatterned multi-layers constituting a whole transparent TFT could reach 72.5%. The high conductivity and transparent multi-layer S/D electrodes for transparent TFTs possessed great potential for the applications of the green and transparent displays industry.

Improvement of Permeation of Solvent-Free Multilayer Encapsulation of Thin Films on Poly(ethylene terephthalate)

NASA Astrophysics Data System (ADS)

Han, Jin-Woo; Kang, Hee-Jin; Kim, Jong-Yeon; Kim, Gwi-Yeol; Seo, Dae-Shik

2006-12-01

In this study, inorganic multilayer thin-film encapsulation is adopted for the first time to protect an organic layer from moisture and oxygen. Inorganic multilayer thin-film encapsulation is deposited onto poly(ethylene terephthalate) (PET) using an electron beam and sputtering. The SiON/SiO2 and parylene layer show the most suitable properties. Under these conditions, the water vapor transmission rate (WVTR) for PET can be reduced from a level of 0.57 g m-2 day-1 (bare substrate) to 1× 10-5 g m-2 day-1 after the application of a SiON and SiO2 layer. These results indicate that PET/parylene/SiO2/SiON barrier coatings have high potential for flexible organic light-emitting diode (OLED) applications.

A multi-layered Fe2O3/graphene composite with mesopores as a catalyst for rechargeable aprotic lithium-oxygen batteries.

PubMed

Feng, Ningning; Mu, Xiaowei; Zheng, Mingbo; Wang, Chaoqiang; Lin, Zixia; Zhang, Xueping; Shi, Yi; He, Ping; Zhou, Haoshen

2016-09-09

Aprotic Li-O2 batteries have attracted a huge amount of interest in the past decade owing to their extremely high energy density. However, identifying a desirable cathodic catalyst for this promising battery system is one of the biggest challenges at present. In this work, a multi-layered Fe2O3/graphene nanosheets (Fe2O3/GNS) composite with sandwich structure was synthesized using an easy thermal casting method, and served as a cathodic catalyst for aprotic Li-O2 batteries. The aprotic Li-O2 cell with the Fe2O3/GNS catalyst demonstrated a better reversibility, lower overpotential for oxygen evolution, and a higher Coulombic efficiency (close to 100%) than those of pure GNS. An excellent rate performance and good cycle stability were also confirmed. The results, characterized by ex and in situ methods, revealed that the dominant discharge product Li2O2 was decomposed below 4.35 V. This superior electrochemical performance is mainly attributed to the unique sandwich structure of the Fe2O3/GNS catalyst with mesopores, which can provide substantially more catalytic sites and prevent direct contact between carbon and Li2O2.

Synthesis, characterization, and performance evaluation of multilayered photoanodes by introducing mesoporous carbon and TiO2 for humic acid adsorption.

PubMed

Hosseini, Soraya; Jahangirian, Hossein; Webster, Thomas J; Soltani, Salman Masoudi; Aroua, Mohamed Kheireddine

2016-01-01

Nanostructured photoanodes were prepared via a novel combination of titanium dioxide (TiO2) nanoparticles and mesoporous carbon (C). Four different photoanodes were synthesized by sol-gel spin coating onto a glassy substrate of fluorine-doped tin oxide. The photocatalytic activities of TiO2, TiO2/C/TiO2, TiO2/C/C/TiO2, and TiO2/C/TiO2/C/TiO2 photoanodes were evaluated by exposing the synthesized photoanodes to UV-visible light. The photocurrent density observed in these photoanodes confirmed that an additional layer of mesoporous carbon could successfully increase the photocurrent density. The highest photocurrent density of ~1.022 mA cm(-2) at 1 V/saturated calomel electrode was achieved with TiO2/C/C/TiO2 under an illumination intensity of 100 mW cm(-2) from a solar simulator. The highest value of surface roughness was measured for a TiO2/C/C/TiO2 combination owing to the presence of two continuous layers of mesoporous carbon. The resulting films had a thickness ranging from 1.605 µm to 5.165 µm after the calcination process. The presence of double-layer mesoporous carbon resulted in a 20% increase in the photocurrent density compared with the TiO2/C/TiO2 combination when only a single mesoporous carbon layer was employed. The improved performance of these photoanodes can be attributed to the enhanced porosity and increased void space due to the presence of mesoporous carbon. For the first time, it has been demonstrated here that the photoelectrochemical performance of TiO2 can be improved by integrating several layers of mesoporous carbon. Comparison of the rate of removal of humic acid by the prepared photoanodes showed that the highest performance from TiO2/C/C/TiO2 was due to the highest photocurrent density generated. Therefore, this study showed that optimizing the sequence of mesoporous carbon layers can be a viable and inexpensive method for enhanced humic acid removal.

Synthesis, characterization, and performance evaluation of multilayered photoanodes by introducing mesoporous carbon and TiO2 for humic acid adsorption

PubMed Central

Hosseini, Soraya; Jahangirian, Hossein; Webster, Thomas J; Soltani, Salman Masoudi; Aroua, Mohamed Kheireddine

2016-01-01

Nanostructured photoanodes were prepared via a novel combination of titanium dioxide (TiO2) nanoparticles and mesoporous carbon (C). Four different photoanodes were synthesized by sol–gel spin coating onto a glassy substrate of fluorine-doped tin oxide. The photocatalytic activities of TiO2, TiO2/C/TiO2, TiO2/C/C/TiO2, and TiO2/C/TiO2/C/TiO2 photoanodes were evaluated by exposing the synthesized photoanodes to UV–visible light. The photocurrent density observed in these photoanodes confirmed that an additional layer of mesoporous carbon could successfully increase the photocurrent density. The highest photocurrent density of ~1.022 mA cm−2 at 1 V/saturated calomel electrode was achieved with TiO2/C/C/TiO2 under an illumination intensity of 100 mW cm−2 from a solar simulator. The highest value of surface roughness was measured for a TiO2/C/C/TiO2 combination owing to the presence of two continuous layers of mesoporous carbon. The resulting films had a thickness ranging from 1.605 µm to 5.165 µm after the calcination process. The presence of double-layer mesoporous carbon resulted in a 20% increase in the photocurrent density compared with the TiO2/C/TiO2 combination when only a single mesoporous carbon layer was employed. The improved performance of these photoanodes can be attributed to the enhanced porosity and increased void space due to the presence of mesoporous carbon. For the first time, it has been demonstrated here that the photoelectrochemical performance of TiO2 can be improved by integrating several layers of mesoporous carbon. Comparison of the rate of removal of humic acid by the prepared photoanodes showed that the highest performance from TiO2/C/C/TiO2 was due to the highest photocurrent density generated. Therefore, this study showed that optimizing the sequence of mesoporous carbon layers can be a viable and inexpensive method for enhanced humic acid removal. PMID:27574426

Highly Crystalline CVD-grown Multilayer MoSe2 Thin Film Transistor for Fast Photodetector

PubMed Central

Jung, Chulseung; Kim, Seung Min; Moon, Hyunseong; Han, Gyuchull; Kwon, Junyeon; Hong, Young Ki; Omkaram, Inturu; Yoon, Youngki; Kim, Sunkook; Park, Jozeph

2015-01-01

Hexagonal molybdenum diselenide (MoSe2) multilayers were grown by chemical vapor deposition (CVD). A relatively high pressure (>760 Torr) was used during the CVD growth to achieve multilayers by creating multiple nuclei based on the two-dimensional crystal growth model. Our CVD-grown multilayer MoSe2 thin-film transistors (TFTs) show p-type-dominant ambipolar behaviors, which are attributed to the formation of Se vacancies generated at the decomposition temperature (650 °C) after the CVD growth for 10 min. Our MoSe2 TFT with a reasonably high field-effect mobility (10 cm2/V · s) exhibits a high photoresponsivity (93.7 A/W) and a fast photoresponse time (τrise ~ 0.4 s) under the illumination of light, which demonstrates the practical feasibility of multilayer MoSe2 TFTs for photodetector applications. PMID:26477744

Prolonged and continuous antibacterial and anti-biofilm activities of thin films embedded with gentamicin-loaded mesoporous silica nanoparticles

NASA Astrophysics Data System (ADS)

Tamanna, Tasnuva; Landersdorfer, Cornelia B.; Ng, Hooi Jun; Bulitta, Jürgen B.; Wood, Peter; Yu, Aimin

2018-05-01

The application of mesoporous silica nanoparticles (MSNs) in drug delivery systems has become highly attractive since the early 2000s. In this study, thin-film coatings embedded with gentamicin-loaded mesoporous silica nanoparticles (MSN-G) were prepared to provide antibacterial and anti-biofilm activity over a prolonged period of time. The prolonged and continuous activity of MSN-G films against Staphylococcus aureus throughout the release period was studied via two methods, namely, (1) disc diffusion of released gentamicin and (2) by shifting the MSN-G thin film to a new agar plate at certain time intervals. The expansion of the inhibition zone from 4.6 ± 0.5 to 9.7 ± 0.5 mm as caused by the released fraction of gentamicin from the first week to the eighth week indicated the controlled and slow release behaviour of loaded antibiotic and prolonged antibacterial efficacy of these films. In addition, the appearance of an inhibition zone after each shifting of the film to a new agar plate was persistent up to 103 days which confirmed that thin films successively prevented bacterial growth over a long period of time. In addition, the anti-biofilm activity of MSN-G films was evaluated by imaging bacterial cells attachment via confocal laser scanning microscopy and scanning electron microscopy. Remarkably, the anti-biofilm performance remained active for more than 2 months. To the best of our knowledge, such a slow and controlled release of antibiotic from nanoparticle embedded thin films with uninterrupted, continuous, and prolonged antibacterial effect for more than 2 months has not been reported yet.

Mesoporous block-copolymer nanospheres prepared by selective swelling.

PubMed

Mei, Shilin; Jin, Zhaoxia

2013-01-28

Block-copolymer (BCP) nanospheres with hierarchical inner structure are of great interest and importance due to their possible applications in nanotechnology and biomedical engineering. Mesoporous BCP nanospheres with multilayered inner channels are considered as potential drug-delivery systems and templates for multifunctional nanomaterials. Selective swelling is a facile pore-making strategy for BCP materials. Herein, the selective swelling-induced reconstruction of BCP nanospheres is reported. Two poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) samples with different compositions (PS(23600)-b-P2VP(10400) and PS(27700)-b-P2VP(4300)) are used as model systems. The swelling reconstruction of PS-b-P2VP in ethanol, 1-pyrenebutyric acid (PBA)/ethanol, or HCl/ethanol (pH = 2.61) is characterized by scanning electron microscopy and transmission electron microscopy. It is observed that the length of the swellable block in BCP is a critical factor in determining the behavior and nanostructures of mesoporous BCP nanospheres in selective swelling. Moreover, it is demonstrated that the addition of PBA modifies the swelling structure of PS(23600)-b-P2VP(10400) through the interaction between PBA and P2VP blocks, which results in BCP nanospheres with patterned pores of controllable size. The patterned pores can be reversibly closed by annealing the mesoporous BCP nanospheres in different selective solvents. The controllable and reversible open/closed reconstruction of BCP nanospheres can be used to enclose functional nanoparticles or drugs inside the nanospheres. These mesoporous BCP nanospheres are further decorated with gold nanoparticles by UV photoreduction. The enlarged decoration area in mesoporous BCP nanospheres will enhance their activity and sensitivity as a catalyst and electrochemical sensor. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controlling drug delivery kinetics from mesoporous titania thin films by pore size and surface energy.

PubMed

Karlsson, Johan; Atefyekta, Saba; Andersson, Martin

2015-01-01

The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D) and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding-diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments.

2009 Insensitive Munitions and Energetic Materials Technology Symposium

DTIC Science & Technology

2009-05-14

Multilayer Structure 1D STIMULI Flat end rod Round end rod Flat cookie -cutter Spherical fragment Simple shaped charge jet Real shaped charge jet Thin plate... cookie -cutter Spherical fragment Simple shaped charge jet Real shaped charge jet Thin plate Constant Temperature Rising Temperature Multilayer...Propellants  Plasticizer mixed into the Propellant - Dough NO SURFACE COATING Formulation Impetus (J/g) Flame Temp (K) Mw (g/mole) A

{ital In-situ} x-ray investigation of hydrogen charging in thin film bimetallic electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jisrawi, N.M.; Wiesmann, H.; Ruckman, M.W.

Hydrogen uptake and discharge by thin metallic films under potentiostatic control was studied using x-ray diffraction at the National Synchrotron Light Source (NSLS). The formation of metal-hydrogen phases in Pd, Pd-capped Nb and Pd/Nb multilayer electrode structures was deduced from x-ray diffraction data and correlated with the cyclic voltammetry (CV) peaks. The x-ray data was also used to construct a plot of the hydrogen concentration as a function of cell potential for a multilayered thin film. {copyright} {ital 1997 Materials Research Society.}

Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Best, James P., E-mail: james.best@empa.ch, E-mail: engelbert.redel@kit.edu, E-mail: christof.woell@kit.edu; Michler, Johann; Maeder, Xavier

2015-09-07

Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth method. Control over respective fabrication processes allowed for tuning of the thickness of the thin film systems with a high degree of precision. It was found that the mechanical indentation of such thin films is significantly affected by the substrate properties; however, elastic parameters were able to be decoupled for constituent thin-film materials (E{sub ITO} ≈ 96.7 GPa, E{sub HKUST−1} ≈ 22.0 GPa).more » For indentation of multilayer stacks, it was found that as the layer thicknesses were increased, while holding the relative thickness of ITO and HKUST-1 constant, the resistance to deformation was significantly altered. Such an observation is likely due to small, albeit significant, changes in film texture, interfacial roughness, size effects, and controlling deformation mechanism as a result of increasing material deposition during processing. Such effects may have consequences regarding the rational mechanical design and utilization of MOF-based hybrid thin-film devices.« less

Simultaneous ultra-long data retention and low power based on Ge10Sb90/SiO2 multilayer thin films

NASA Astrophysics Data System (ADS)

You, Haipeng; Hu, Yifeng; Zhu, Xiaoqin; Zou, Hua; Song, Sannian; Song, Zhitang

2018-02-01

In this article, Ge10Sb90/SiO2 multilayer thin films were prepared to improve thermal stability and data retention for phase change memory. Compared with Ge10Sb90 monolayer thin film, Ge10Sb90 (1 nm)/SiO2 (9 nm) multilayer thin film had higher crystallization temperature and resistance contrast between amorphous and crystalline states. Annealed Ge10Sb90 (1 nm)/SiO2 (9 nm) had uniform grain with the size of 15.71 nm. After annealing, the root-mean-square surface roughness for Ge10Sb90 (1 nm)/SiO2 (9 nm) thin film increased slightly from 0.45 to 0.53 nm. The amorphization time for Ge10Sb90 (1 nm)/SiO2 (9 nm) thin film (2.29 ns) is shorter than Ge2Sb2Te5 (3.56 ns). The threshold voltage of a cell based on Ge10Sb90 (1 nm)/SiO2 (9 nm) (3.57 V) was smaller than GST (4.18 V). The results indicated that Ge10Sb90/SiO2 was a promising phase change thin film with high thermal ability and low power consumption for phase change memory application.

Highly ordered, accessible and nanocrystalline mesoporous TiO₂ thin films on transparent conductive substrates.

PubMed

Violi, Ianina L; Perez, M Dolores; Fuertes, M Cecilia; Soler-Illia, Galo J A A

2012-08-01

Highly porous (V(mesopore) = 25-50%) and ordered mesoporous titania thin films (MTTF) were prepared on ITO (indium tin oxide)-covered glass by a fast two-step method. The effects of substrate surface modification and thermal treatment on pore order, accessibility and crystallinity of the MTTF were systematically studied for MTTF deposited onto bare and titania-modified ITO. MTTF exposed briefly to 550 °C resulted in highly ordered films with grid-like structures, enlarged pore size, and increased accessible pore volume when prepared onto the modified ITO substrate. Mesostructure collapse and no significant change in pore volume were observed for MTTF deposited on bare ITO substrates. Highly crystalline anatase was obtained for MTTF prepared on the modified-ITO treated at high temperatures, establishing the relationship between grid-like structures and titania crystallization. Photocatalytic activity was maximized for samples with increased crystallization and high accessible pore volume. In this manner, a simple way of designing materials with optimized characteristics for optoelectronic applications was achieved through the modification of the ITO surface and a controlled thermal treatment.

Epitaxy: Programmable Atom Equivalents Versus Atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Mary X.; Seo, Soyoung E.; Gabrys, Paul A.

The programmability of DNA makes it an attractive structure-directing ligand for the assembly of nanoparticle superlattices in a manner that mimics many aspects of atomic crystallization. However, the synthesis of multilayer single crystals of defined size remains a challenge. Though previous studies considered lattice mismatch as the major limiting factor for multilayer assembly, thin film growth depends on many interlinked variables. Here, a more comprehensive approach is taken to study fundamental elements, such as the growth temperature and the thermodynamics of interfacial energetics, to achieve epitaxial growth of nanoparticle thin films. Under optimized equilibrium conditions, single crystal, multilayer thin filmsmore » can be synthesized over 500 × 500 μm2 areas on lithographically patterned templates. Importantly, these superlattices follow the same patterns of crystal growth demonstrated in thin film atomic deposition, allowing for these processes to be understood in the context of well-studied atomic epitaxy, and potentially enabling a nanoscale model to study fundamental crystallization processes.« less

Doped SnO₂ transparent conductive multilayer thin films explored by continuous composition spread.

PubMed

Lee, Jin Ju; Ha, Jong-Yoon; Choi, Won-Kook; Cho, Yong Soo; Choi, Ji-Won

2015-04-13

Mn-doped SnO₂ thin films were fabricated by a continuous composition spread (CCS) method on a glass substrate at room temperature to find optimized compositions. The fabricated materials were found to have a lower resistivity than pure SnO₂ thin films because of oxygen vacancies generated by Mn doping. As Mn content was increased, resistivity was found to decrease for limited doping concentrations. The minimum thin film resistivity was 0.29 Ω-cm for a composition of 2.59 wt % Mn-doped SnO₂. The Sn-O vibrational stretching frequency in FT-IR showed a blue shift, consistent with oxygen deficiency. Mn-doped SnO₂/Ag/Mn-doped SnO₂ multilayer structures were fabricated using this optimized composition deposited by an on-axis radio frequency (RF) sputter. The multilayer transparent conducting oxide film had a resistivity of 7.35 × 10⁻⁵ Ω-cm and an average transmittance above 86% in the 550 nm wavelength region.

Multilayer bioactive glass/zirconium titanate thin films in bone tissue engineering and regenerative dentistry

PubMed Central

Mozafari, Masoud; Salahinejad, Erfan; Shabafrooz, Vahid; Yazdimamaghani, Mostafa; Vashaee, Daryoosh; Tayebi, Lobat

2013-01-01

Surface modification, particularly coatings deposition, is beneficial to tissue-engineering applications. In this work, bioactive glass/zirconium titanate composite thin films were prepared by a sol-gel spin-coating method. The surface features of the coatings were studied by scanning electron microscopy, atomic force microscopy, and spectroscopic reflection analyses. The results show that uniform and sound multilayer thin films were successfully prepared through the optimization of the process variables and the application of carboxymethyl cellulose as a dispersing agent. Also, it was found that the thickness and roughness of the multilayer coatings increase nonlinearly with increasing the number of the layers. This new class of nanocomposite coatings, comprising the bioactive and inert components, is expected not only to enhance bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. PMID:23641155

Direct Detection of Potential Pyrethroids in Yangtze River via an Imprinted Multilayer Phosphorescence Probe.

PubMed

Chen, Li; Lv, Xiaodong; Dai, Jiangdong; Sun, Lin; Huo, Pengwei; Li, Chunxiang; Yan, Yongsheng

2018-01-01

A novel tailored multilayer probe for monitoring potential pyrethroids in the Yangtze River was proposed. The room-temperature phosphorescence method was applied to realize a detection strategy that is superior to the fluorescence method. Efficient Mn-doped ZnS quantum dots with uniform size of 4.6 nm were firstly coated with a mesoporous silica to obtain a suitable intermediate transition layer, then an imprinted layer containing bifenthrin specific recognition sites was anchored. Characterizations verified the multilayer structure convincingly and the detection process relied on the electron transfer-induced fluorescence quenching mechanism. Optional detection time and standard detection curve were obtained within a concentration range from 5.0 to 50 μmol L -1 . The stability was verified to be good after 12 replicates. Feasibility of the probe was proved by monitoring water samples from the Zhenjiang reach of the Yangtze River. The probe offers promise for direct bifenthrin detection in unknown environmental water with an accurate and stable phosphorescence analysis strategy.

Mesoporous Silicate Materials in Sensing

PubMed Central

Melde, Brian J.; Johnson, Brandy J.; Charles, Paul T.

2008-01-01

Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes greater than 2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through co-condensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules. PMID:27873810

Laser-induced periodic surface structures formation on mesoporous silicon from nanoparticles produced by picosecond and femtosecond laser shots

NASA Astrophysics Data System (ADS)

Talbi, Abderazek; Kaya-Boussougou, Sostaine; Sauldubois, Audrey; Stolz, Arnaud; Boulmer-Leborgne, Chantal; Semmar, Nadjib

2017-07-01

This paper deals with the formation of laser-induced periodic surface structures (LIPSS) on mesoporous silicon thin films induced by two laser regimes in the UV range: picosecond and femtosecond. Different LIPSS formation mechanisms from nanoparticles, mainly coalescence and agglomeration, have been evidenced by scanning electron microscopy analysis. The apparition of a liquid phase during both laser interaction at low fluence (20 mJ/cm2) and after a large number of laser pulses (up to 12,000) has been also shown with 100 nm size through incubation effect. Transmission electron microscopy analyses have been conducted to investigate the molten phase structures below and inside LIPSS. Finally, it has shown that LIPSS are composed of amorphous silicon when mesoporous silicon is irradiated by laser beam in both regimes. Nevertheless, mesoporous silicon located between LIPSS stays crystallized.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lereu, Aude L.; Zerrad, M.; Passian, Ali

In photonics, the field concentration and enhancement have been major objectives for achieving size reduction and device integration. Plasmonics offers resonant field confinement and enhancement, but ultra-sharp optical resonances in all-dielectric multi-layer thin films are emerging as a powerful contestant. Thus, applications capitalizing upon stronger and sharper optical resonances and larger field enhancements could be faced with a choice for the superior platform. Here in this paper, we present a comparison between plasmonic and dielectric multi-layer thin films for their resonance merits. We show that the remarkable characteristics of the resonance behavior of optimized dielectric multi-layers can outweigh those ofmore » their metallic counterpart.« less

Effect of ordered mesoporous carbon contact layer on the sensing performance of sputtered RuO2 thin film pH sensor.

PubMed

Lonsdale, W; Maurya, D K; Wajrak, M; Alameh, K

2017-03-01

The effect of contact layer on the pH sensing performance of a sputtered RuO 2 thin film pH sensor is investigated. The response of pH sensors employing RuO 2 thin film electrodes on screen-printed Pt, carbon and ordered mesoporous carbon (OMC) contact layers are measured over a pH range from 4 to 10. Working electrodes with OMC contact layer are found to have Nernstian pH sensitivity (-58.4mV/pH), low short-term drift rate (5.0mV/h), low hysteresis values (1.13mV) and fast reaction times (30s), after only 1h of conditioning. A pH sensor constructed with OMC carbon contact layer displays improved sensing performance compared to Pt and carbon-based counterparts, making this electrode more attractive for applications requiring highly-accurate pH sensing with reduced conditioning time. Copyright © 2016 Elsevier B.V. All rights reserved.

MoRu/Be multilayers for extreme ultraviolet applications

DOEpatents

Bajt, Sasa C.; Wall, Mark A.

2001-01-01

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.

SmNiO3/NdNiO3 thin film multilayers

NASA Astrophysics Data System (ADS)

Girardot, C.; Pignard, S.; Weiss, F.; Kreisel, J.

2011-06-01

Rare earth nickelates RENiO3 (RE =rare earth), which attract interest due to their sharp metal-insulator phase transition, are instable in bulk form due to the necessity of an important oxygen pressure to stabilize Ni in its 3+ state of oxidation. Here, we report the stabilization of RE nickelates in [(SmNiO3)t/(NdNiO3)t]n thin film multilayers, t being the thickness of layers alternated n times. Both bilayers and multilayers have been deposited by metal-organic chemical vapor deposition. The multilayer structure and the presence of the metastable phases SmNiO3 and NdNiO3 are evidenced from by x-ray and Raman scattering. Electric measurements of a bilayer structure further support the structural quality of the embedded RE nickelate layers.

Sb7Te3/Ge multilayer films for low power and high speed phase-change memory

NASA Astrophysics Data System (ADS)

Chen, Shiyu; Wu, Weihua; Zhai, Jiwei; Song, Sannian; Song, Zhitang

2017-06-01

Phase-change memory has attracted enormous attention for its excellent properties as compared to flash memories due to their high speed, high density, better date retention and low power consumption. Here we present Sb7Te3/Ge multilayer films by using a magnetron sputtering method. The 10 years’ data retention temperature is significantly increased compared with pure Sb7Te3. When the annealing temperature is above 250 °C, the Sb7Te3/Ge multilayer thin films have better interface properties, which renders faster crystallization speed and high thermal stability. The decrease in density of ST/Ge multilayer films is only around 5%, which is very suitable for phase change materials. Moreover, the low RESET power benefits from high resistivity and better thermal stability in the PCM cells. This work demonstrates that the multilayer configuration thin films with tailored properties are beneficial for improving the stability and speed in phase change memory applications.

Laser processing of thin-film multilayer structures: comparison between a 3D thermal model and experimental results.

PubMed

Naghshine, Babak B; Kiani, Amirkianoosh

2017-01-01

In this research, a numerical model is introduced for simulation of laser processing of thin film multilayer structures, to predict the temperature and ablated area for a set of laser parameters including average power and repetition rate. Different thin-films on Si substrate were processed by nanosecond Nd:YAG laser pulses and the experimental and numerical results were compared to each other. The results show that applying a thin film on the surface can completely change the temperature field and vary the shape of the heat affected zone. The findings of this paper can have many potential applications including patterning the cell growth for biomedical applications and controlling the grain size in fabrication of polycrystalline silicon (poly-Si) thin-film transistors (TFTs).

Photovoltaic properties of multilayered quantum dot/quantum rod-sensitized TiO₂ solar cells fabricated by SILAR and electrophoresis.

PubMed

Cerdán-Pasarán, Andrea; López-Luke, Tzarara; Esparza, Diego; Zarazúa, Isaac; De la Rosa, Elder; Fuentes-Ramírez, Rosalba; Alatorre-Ordaz, Alejandro; Sánchez-Solís, Ana; Torres-Castro, Alejandro; Zhang, Jin Z

2015-07-28

A multilayered semiconductor sensitizer structure composed of three differently sized CdSe quantum rods (QRs), labeled as Q530, Q575, Q590, were prepared and deposited on the surface of mesoporous TiO2 nanoparticles by electrophoretic deposition (EPD) for photovoltaic applications. By varying the arrangement of layers as well as the time of EPD, the photoconversion efficiency was improved from 2.0% with the single layer of CdSe QRs (TiO2/Q590/ZnS) to 2.9% for multilayers (TiO2/Q590Q575/ZnS). The optimal EPD time was shorter for the multilayered structures. The effect of CdS quantum dots (QDs) deposited by successive ionic layer adsorption and reaction (SILAR) was also investigated. The addition of CdS QDs resulted in the enhancement of efficiency to 4.1% for the configuration (TiO2/CdS/Q590Q575/ZnS), due to increased photocurrent and photovoltage. Based on detailed structural, optical, and photoelectrical studies, the increased photocurrent is attributed to broadened light absorption while the increased voltage is due to a shift in the relevant energy levels.

Preliminary Reports, Memoranda and Technical Notes of the Materials Research Council Summer Conference, La Jolla, California

DTIC Science & Technology

1983-07-01

Multilayer Thin Film materials M. S. Wrighton ...................................... 26 •.. Line Defects in Langmuir - Blodgett Films J. P. Hirth...of Langmuir and Blodgett can be used to prepare monolayers and multilayers of organic materials on a o, variety of substrates. The films of organic...references therein. * 2. Cf. Thin Solid Films, 99, (1982) from the proceedings of the "* . International Conference on Langmuir - Blodgett Films held

Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

PubMed Central

Nur-E-Alam, Mohammad; Vasiliev, Mikhail; Kotov, Viacheslav A.; Balabanov, Dmitry; Akimov, Ilya; Alameh, Kamal

2015-01-01

The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed. PMID:28788043

Shock compression response of highly reactive Ni + Al multilayered thin foils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelly, Sean C.; Thadhani, Naresh N., E-mail: naresh.thadhani@mse.gatech.edu

2016-03-07

The shock-compression response of Ni + Al multilayered thin foils is investigated using laser-accelerated thin-foil plate-impact experiments over the pressure range of 2 to 11 GPa. The foils contain alternating Ni and Al layers (parallel but not flat) of nominally 50 nm bilayer spacing. The goal is to determine the equation of state and shock-induced reactivity of these highly reactive fully dense thin-foil materials. The laser-accelerated thin-foil impact set-up involved combined use of photon-doppler-velocimetry to monitor the acceleration and impact velocity of an aluminum flyer, and VISAR interferometry was used to monitor the back free-surface velocity of the impacted Ni + Al multilayered target. The shock-compressionmore » response of the Ni + Al target foils was determined using experimentally measured parameters and impedance matching approach, with error bars identified considering systematic and experimental errors. Meso-scale CTH shock simulations were performed using real imported microstructures of the cross-sections of the multilayered Ni + Al foils to compute the Hugoniot response (assuming no reaction) for correlation with their experimentally determined equation of state. It was observed that at particle velocities below ∼150 m/s, the experimentally determined equation of state trend matches the CTH-predicted inert response and is consistent with the observed unreacted state of the recovered Ni + Al target foils from this velocity regime. At higher particle velocities, the experimentally determined equation of state deviates from the CTH-predicted inert response. A complete and self-sustained reaction is also seen in targets recovered from experiments performed at these higher particle velocities. The deviation in the measured equation of state, to higher shock speeds and expanded volumes, combined with the observation of complete reaction in the recovered multilayered foils, confirmed via microstructure characterization, is indicative of the occurrence of shock-induced chemical reaction occurring in the time-scale of the high-pressure state. TEM characterization of recovered shock-compressed (unreacted) Ni + Al multilayered foils exhibits distinct features of constituent mixing revealing jetted layers and inter-mixed regions. These features were primarily observed in the proximity of the undulations present in the alternating layers of the Ni + Al starting foils, suggesting the important role of such instabilities in promoting shock-induced intermetallic-forming reactions in the fully dense highly exothermic multilayered thin foils.« less

Atmospheric deposition process for enhanced hybrid organic-inorganic multilayer barrier thin films for surface protection

NASA Astrophysics Data System (ADS)

Rehman, Mohammad Mutee ur; Kim, Kwang Tae; Na, Kyoung Hoan; Choi, Kyung Hyun

2017-11-01

In this study, organic polymer poly-vinyl acetate (PVA) and inorganic aluminum oxide (Al2O3) have been used together to fabricate a hybrid barrier thin film for the protection of PET substrate. The organic thin films of PVA were developed through roll to roll electrohydrodynamic atomization (R2R-EHDA) whereas the inorganic thin films of Al2O3 were grown by roll to roll spatial atmospheric atomic layer deposition (R2R-SAALD) for mass production. The use of these two technologies together to develop a multilayer hybrid organic-inorganic barrier thin films under atmospheric conditions is reported for the first time. These multilayer hybrid barrier thin films are fabricated on flexible PET substrate. Each layer of Al2O3 and PVA in barrier thin film exhibited excellent morphological, chemical and optical properties. Extremely uniform and atomically thin films of Al2O3 with average arithmetic roughness (Ra) of 1.64 nm and 1.94 nm respectively concealed the non-uniformity and irregularities in PVA thin films with Ra of 2.9 nm and 3.6 nm respectively. The optical transmittance of each layer was ∼ 80-90% while the water vapor transmission rate (WVTR) of hybrid barrier was in the range of ∼ 2.3 × 10-2 g m-2 day-1 with a total film thickness of ∼ 200 nm. Development of such hybrid barrier thin films with mass production and low cost will allow various flexible electronic devices to operate in atmospheric conditions without degradation of their properties.

Nanomechanical Behavior of High Gas Barrier Multilayer Thin Films.

PubMed

Humood, Mohammad; Chowdhury, Shahla; Song, Yixuan; Tzeng, Ping; Grunlan, Jaime C; Polycarpou, Andreas A

2016-05-04

Nanoindentation and nanoscratch experiments were performed on thin multilayer films manufactured using the layer-by-layer (LbL) assembly technique. These films are known to exhibit high gas barrier, but little is known about their durability, which is an important feature for various packaging applications (e.g., food and electronics). Films were prepared from bilayer and quadlayer sequences, with varying thickness and composition. In an effort to evaluate multilayer thin film surface and mechanical properties, and their resistance to failure and wear, a comprehensive range of experiments were conducted: low and high load indentation, low and high load scratch. Some of the thin films were found to have exceptional mechanical behavior and exhibit excellent scratch resistance. Specifically, nanobrick wall structures, comprising montmorillonite (MMT) clay and polyethylenimine (PEI) bilayers, are the most durable coatings. PEI/MMT films exhibit high hardness, large elastic modulus, high elastic recovery, low friction, low scratch depth, and a smooth surface. When combined with the low oxygen permeability and high optical transmission of these thin films, these excellent mechanical properties make them good candidates for hard coating surface-sensitive substrates, where polymers are required to sustain long-term surface aesthetics and quality.

The effect of underlayers on the reversal of perpendicularly magnetized multilayer thin films for magnetic micro- and nanoparticles

NASA Astrophysics Data System (ADS)

Vemulkar, T.; Mansell, R.; Petit, D. C. M. C.; Cowburn, R. P.; Lesniak, M. S.

2017-01-01

Perpendicularly magnetized microparticles offer the ability to locally apply high torques on soft matter under an applied magnetic field. These particles are engineered to have a zero remanence magnetic configuration via synthetic antiferromagnetic coupling using a Ru coupling interlayer. The flexibility offered by the top down thin film fabrication process in a CoFeB/Pt perpendicular thin film is demonstrated by using the Pt interlayer thicknesses in a Pt/Ru/Pt antiferromagnetic coupling multilayer to tune the applied magnetic field value of the easy axis spin-flip transition to saturation and hence the field value at which the magnetic particles are magnetically activated via a distinct transition to saturation. The importance of a Ta buffer layer on the magnetic behavior of the stack is shown. While Au capping layers are desirable for biotechnology applications, we demonstrate that they can drastically change the nucleation and propagation of domains in the film, thereby altering the reversal behavior of the thin film. The effect of Au underlayers on a multilayer thin film composed of repeated motifs of a synthetic antiferromagnetic building block is also investigated.

Radiation response of cubic mesoporous silicate and borosilicate thin films

NASA Astrophysics Data System (ADS)

Manzini, Ayelén; Alurralde, Martín; Luca, Vittorio

2018-01-01

The radiation response has been studied of cubic mesoporous silicate and borosilicate thin films having different boron contents prepared using the block copolymer template Brij 58 and the dip coating technique. The degree of pore ordering of the films was analysed using low-angle X-ray diffraction and film thickness measured by X-ray reflectivity. For films calcined at 350 °C, the incorporation of boron resulted in a reproducible oscillatory variation in the d-spacing and intensity of the primary reflection as a function of boron content. A clear peak was observed in the d-spacing at 5-10 mol% boron incorporation. For borosilicate films of a given composition an overall suppression of d-spacing was observed as a function of aging time relative to films that did not contain boron. This was ascribed to a slow condensation process. The films were irradiated in pile with neutrons and with iodine ions at energies of 180 keV and 70 MeV. Neutron irradiation of the silicate thin films for periods up to 30 days and aged for 400 days resulted in little reduction in either d-spacing or intensity of the primary low-angle X-ray reflection indicating that the films retained their mesopore ordering. In contrast borosilicate films for which the B (n, α) reaction was expected to result in enhanced displacement damage showed much larger variations in X-ray parameters. For these films short irradiation times resulted in a reduction of the d-spacing and intensity of the primary reflections considerably beyond that observed through aging. It is concluded that prolonged neutron irradiation and internal α irradiation have only a small, although measurable, impact on mesoporous borosilicate thin films increasing the degree of condensation and increasing unit cell contraction. When these borosilicate films were irradiated with iodine ions, more profound changes occurred. The pore ordering of the films was significantly degraded when low energy ions were used. In some cases the degree of damage was such that no low-angle reflection could be observed. This degradation of pore ordering was confirmed in scanning electron microscopy images of the irradiated films.

Multilayer films with sharp, stable interfaces for use in EUV and soft X-ray application

DOEpatents

Barbee, Jr., Troy W.; Bajt, Sasa

2002-01-01

The reflectivity and thermal stability of Mo/Si (molybdenum/silicon) multilayer films, used in soft x-ray and extreme ultraviolet region, is enhanced by deposition of a thin layer of boron carbide (e.g., B.sub.4 C) between alternating layers of Mo and Si. The invention is useful for reflective coatings for soft X-ray and extreme ultraviolet optics, multilayer for masks, coatings for other wavelengths and multilayers for masks that are more thermally stable than pure Mo/Si multilayers

Cross-sectional TEM specimen preparation for W/B{sub 4}C multilayer sample using FIB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mondal, Puspen, E-mail: puspen@rrcat.gov.in; Pradhan, P. C.; Tiwari, Pragya

2016-05-23

A recent emergence of a cross-beam scanning electron microscopy (SEM)/focused-ion-beam (FIB) system have given choice to fabricate cross-sectional transmission electron microscopy (TEM) specimen of thin film multilayer sample. A 300 layer pair thin film multilayer sample of W/B{sub 4}C was used to demonstrate the specimen lift-out technique in very short time as compared to conventional cross-sectional sample preparation technique. To get large area electron transparent sample, sample prepared by FIB is followed by Ar{sup +} ion polishing at 2 kV with grazing incident. The prepared cross-sectional sample was characterized by transmission electron microscope.

Surface plasmons and Bloch surface waves: Towards optimized ultra-sensitive optical sensors

DOE PAGES

Lereu, Aude L.; Zerrad, M.; Passian, Ali; ...

2017-07-07

In photonics, the field concentration and enhancement have been major objectives for achieving size reduction and device integration. Plasmonics offers resonant field confinement and enhancement, but ultra-sharp optical resonances in all-dielectric multi-layer thin films are emerging as a powerful contestant. Thus, applications capitalizing upon stronger and sharper optical resonances and larger field enhancements could be faced with a choice for the superior platform. Here in this paper, we present a comparison between plasmonic and dielectric multi-layer thin films for their resonance merits. We show that the remarkable characteristics of the resonance behavior of optimized dielectric multi-layers can outweigh those ofmore » their metallic counterpart.« less

Far infrared filters for the Galileo-Jupiter and other missions

NASA Technical Reports Server (NTRS)

Seeley, J. S.; Hunneman, R.; Whatley, A.

1981-01-01

Progress in the development of FIR multilayer interference filters for the net flux radiometer and photopolarizing radiometer to be carried on board the Galileo mission to Jupiter is reported. The multilayer interference technique has been extended to the region above 40 microns by the use of PbTe/II-VI materials in hard-coated combination, with the thickest layers composed of CdSe QWOT at 74 microns and PbTe QWOT. Improvements have also been obtained in filters below 20 microns on the basis of the Chebyshev stack design. A composite filter cutting on steeply at 40 microns has been designed which employs a thin crystal quartz substrate, shorter wavelength absorption in ZnS and As2S3 thin films, and supplementary multilayer interference. Finally, absorptive filters have been developed based on II-VI compounds in multilayer combination with KRS-5 (or 6) on a KRS-5 (or 6) substrate

Enhancement of Fluorescence-Based Sandwich Immunoassay Using Multilayered Microplates Modified with Plasma-Polymerized Films

PubMed Central

Yano, Kazuyoshi; Iwasaki, Akira

2016-01-01

A functional modification of the surface of a 96-well microplate coupled with a thin layer deposition technique is demonstrated for enhanced fluorescence-based sandwich immunoassays. The plasma polymerization technique enabling the deposition of organic thin films was employed for the modification of the well surface of a microplate. A silver layer and a plasma-polymerized film were consecutively deposited on the microplate as a metal mirror and the optical interference layer, respectively. When Cy3-labeled antibody was applied to the wells of the resulting multilayered microplate without any immobilization step, greatly enhanced fluorescence was observed compared with that obtained with the unmodified one. The same effect could be also exhibited for an immunoassay targeting antigen directly adsorbed on the multilayered microplate. Furthermore, a sandwich immunoassay for the detection of interleukin 2 (IL-2) was performed with the multilayered microplates, resulting in specific and 88-fold–enhanced fluorescence detection. PMID:28029144

In situ fabrication of electrochemically grown mesoporous metallic thin films by anodic dissolution in deep eutectic solvents.

PubMed

Renjith, Anu; Roy, Arun; Lakshminarayanan, V

2014-07-15

We describe here a simple electrodeposition process of forming thin films of noble metallic nanoparticles such as Au, Ag and Pd in deep eutectic solvents (DES). The method consists of anodic dissolution of the corresponding metal in DES followed by the deposition on the cathodic surface. The anodic dissolution process in DES overcomes the problems associated with copious hydrogen and oxygen evolution on the electrode surface when carried out in aqueous medium. The proposed method utilizes the inherent abilities of DES to act as a reducing medium while simultaneously stabilizing the nanoparticles that are formed. The mesoporous metal films were characterized by SEM, XRD and electrochemical techniques. Potential applications of these substrates in surface enhanced Raman spectroscopy and electrocatalysis have been investigated. A large enhancement of Raman signal of analyte was achieved on the mesoporous silver substrate after removing all the stabilizer molecules from the surface by calcination. The highly porous texture of the electrodeposited film provides superior electro catalytic performance for hydrogen evolution reaction (HER). The mechanisms of HER on the fabricated substrates were studied by Tafel analysis and electrochemical impedance spectroscopy (EIS). Copyright © 2014 Elsevier Inc. All rights reserved.

Verification of antiferromagnetic exchange coupling at room temperature using polar magneto-optic Kerr effect in thin EuS/Co multilayers with perpendicular magnetic anisotropy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goschew, A., E-mail: alexander.goschew@fu-berlin.de; Scott, M.; Fumagalli, P.

2016-08-08

We report on magneto-optic Kerr measurements in polar geometry carried out on a series of thin Co/EuS multilayers on suitable Co/Pd-multilayer substrates. Thin Co/EuS multilayers of a few nanometers individual layer thickness usually have their magnetization in plane. Co/Pd multilayers introduce a perpendicular magnetic anisotropy in the Co/EuS layers deposited on top, thus making it possible to measure magneto-optic signals in the polar geometry in remanence in order to study exchange coupling. Magneto-optic Kerr-effect spectra and hysteresis loops were recorded in the visible and ultraviolet photon-energy range at room temperature. The EuS contribution to the magneto-optic signal is extracted atmore » 4.1 eV by combining hysteresis loops measured at different photon energies with polar magneto-optic Kerr-effect spectra recorded in remanence and in an applied magnetic field of 2.2 T. The extracted EuS signal shows clear signs of antiferromagnetic coupling of the Eu magnetic moments to the Co layers. This implies that the ordering temperature of at least a fraction of the EuS layers is above room temperature proving that magneto-optic Kerr-effect spectroscopy can be used here as a quasi-element-specific method.« less

In-depth porosity control of mesoporous silicon layers by an anodization current adjustment

NASA Astrophysics Data System (ADS)

Lascaud, J.; Defforge, T.; Certon, D.; Valente, D.; Gautier, G.

2017-12-01

The formation of thick mesoporous silicon layers in P+-type substrates leads to an increase in the porosity from the surface to the interface with silicon. The adjustment of the current density during the electrochemical etching of porous silicon is an intuitive way to control the layer in-depth porosity. The duration and the current density during the anodization were varied to empirically model porosity variations with layer thickness and build a database. Current density profiles were extracted from the model in order to etch layer with in-depth control porosity. As a proof of principle, an 80 μm-thick porous silicon multilayer was synthetized with decreasing porosities from 55% to 35%. The results show that the assessment of the in-depth porosity could be significantly enhanced by taking into account the pure chemical etching of the layer in the hydrofluoric acid-based electrolyte.

The Role of Annealing Process in Ag-Based BaSnO3 Multilayer Thin Films.

PubMed

Wu, Muying; Yu, Shihui; He, Lin; Yang, Lei; Zhang, Weifeng

2016-12-01

The BaSnO3/Ag/BaSnO3 multilayer structure was designed and fabricated on a quartz glass by magnetron sputtering, followed by an annealing process at a temperature from 150 to 750 °C in air. In this paper, we investigated the influence of the annealing temperature on the structural, optical, and electrical properties of the multilayers and proposed the mechanisms of conduction and transmittance. The maximum value of the figure of merit of 31.8 × 10(-3) Ω(-1) was achieved for the BaSnO3/Ag/BaSnO3 multilayer thin films annealed at 150 °C, while the average optical transmittance in the visible ranges was >84 %, the resistivity was 5.71 × 10(-5) Ω cm, and the sheet resistance was 5.57 Ω/sq. When annealed at below 600 °C, the values of resistivity and transmittance of the multilayers were within an acceptable range (resistivity <5.0 × 10(-4) Ω cm, transmittance >80 %). The observed property of the multilayer film is suitable for the application of transparent conductive electrodes.

[The role of BCP in electroluminescence of multilayer organic light-emitting devices].

PubMed

Deng, Zhao-Ru; Yang, Sheng-Yi; Lou, Zhi-Dong; Meng, Ling-Chuan

2009-03-01

As a hole-blocking layer, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) is usually used in blue and white light electroluminescent devices. The ability of blocking holes of BCP layer depends on its thickness, and basically holes can tunnel through thin BCP layer. In order to know the role of BCP layer in electroluminescence (EL) of multilayer organic light-emitting diodes (OLEDs), in the present paper, the authors designed a multilayer OLED ITO/NPB/BCP/Alq3 : DCJTB/Alq3/Al and investigated the influence of thickness of BCP on the EL spectra of multilayer OLEDs at different applied voltages. The experimental data show that thin BCP layer can block holes partially and tune the energy transfer between different emissive layers, and in this way, it is easy to obtain white emission, but its EL spectra will change with the applied voltages. The EL spectra of multilayer device will remain relatively stable when BCP layer is thick enough, and the holes can hardly tunnel through when the thickness of BCP layer is more than 15 nm. Furthermore, the stability of EL spectra of the multilayer OLED at different applied voltages was discussed.

Color tunable low cost transparent heat reflector using copper and titanium oxide for energy saving application

PubMed Central

Dalapati, Goutam Kumar; Masudy-Panah, Saeid; Chua, Sing Teng; Sharma, Mohit; Wong, Ten It; Tan, Hui Ru; Chi, Dongzhi

2016-01-01

Multilayer coating structure comprising a copper (Cu) layer sandwiched between titanium dioxide (TiO2) were demonstrated as a transparent heat reflecting (THR) coating on glass for energy-saving window application. The main highlight is the utilization of Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass. Color tunable transparent heat reflecting coating was realized through the design of multilayer structure and process optimization. The impact of thermal treatment on the overall performance of sputter deposited TiO2/Cu/TiO2 multilayer thin film on glass substrate is investigated in detail. Significant enhancement of transmittance in the visible range and reflectance in the infra-red (IR) region has been observed after thermal treatment of TiO2/Cu/TiO2 multilayer thin film at 500 °C due to the improvement of crystal quality of TiO2. Highest visible transmittance of 90% and IR reflectance of 85% at a wavelength of 1200 nm are demonstrated for the TiO2/Cu/TiO2 multilayer thin film after annealing at 500 °C. Performance of TiO2/Cu/TiO2 heat reflector coating decreases after thermal treatment at 600 °C. The wear performance of the TiO2/Cu/TiO2 multilayer structure has been evaluated through scratch hardness test. The present work shows promising characteristics of Cu-based THR coating for energy-saving building industry. PMID:26846687

Color tunable low cost transparent heat reflector using copper and titanium oxide for energy saving application.

PubMed

Dalapati, Goutam Kumar; Masudy-Panah, Saeid; Chua, Sing Teng; Sharma, Mohit; Wong, Ten It; Tan, Hui Ru; Chi, Dongzhi

2016-02-05

Multilayer coating structure comprising a copper (Cu) layer sandwiched between titanium dioxide (TiO2) were demonstrated as a transparent heat reflecting (THR) coating on glass for energy-saving window application. The main highlight is the utilization of Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass. Color tunable transparent heat reflecting coating was realized through the design of multilayer structure and process optimization. The impact of thermal treatment on the overall performance of sputter deposited TiO2/Cu/TiO2 multilayer thin film on glass substrate is investigated in detail. Significant enhancement of transmittance in the visible range and reflectance in the infra-red (IR) region has been observed after thermal treatment of TiO2/Cu/TiO2 multilayer thin film at 500 °C due to the improvement of crystal quality of TiO2. Highest visible transmittance of 90% and IR reflectance of 85% at a wavelength of 1200 nm are demonstrated for the TiO2/Cu/TiO2 multilayer thin film after annealing at 500 °C. Performance of TiO2/Cu/TiO2 heat reflector coating decreases after thermal treatment at 600 °C. The wear performance of the TiO2/Cu/TiO2 multilayer structure has been evaluated through scratch hardness test. The present work shows promising characteristics of Cu-based THR coating for energy-saving building industry.

Self-Assembled Multilayer Structure and Enhanced Thermochromic Performance of Spinodally Decomposed TiO2-VO2 Thin Film.

PubMed

Sun, Guangyao; Zhou, Huaijuan; Cao, Xun; Li, Rong; Tazawa, Masato; Okada, Masahisa; Jin, Ping

2016-03-23

Composite films of VO2-TiO2 were deposited on sapphire (11-20) substrate by cosputtering method. Self-assembled well-ordered multilayer structure with alternating Ti- and V-rich epitaxial thin layer was obtained by thermal annealing via a spinodal decomposition mechanism. The structured thermochromic films demonstrate superior optical modulation upon phase transition, with significantly reduced transition temperature. The results provide a facile and novel approach to fabricate smart structures with excellent performance.

Low temperature reactive bonding

DOEpatents

Makowiecki, D.M.; Bionta, R.M.

1995-01-17

The joining technique is disclosed that requires no external heat source and generates very little heat during joining. It involves the reaction of thin multilayered films deposited on faying surfaces to create a stable compound that functions as an intermediate or braze material in order to create a high strength bond. While high temperatures are reached in the reaction of the multilayer film, very little heat is generated because the films are very thin. It is essentially a room temperature joining process. 5 figures.

Thin film photovoltaic device with multilayer substrate

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1984-01-01

A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

Magnetic spin structure and magnetoelectric coupling in BiFeO{sub 3}-BaTiO{sub 3} multilayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazenka, Vera, E-mail: Vera.Lazenka@fys.kuleuven.be; Modarresi, Hiwa; Bisht, Manisha

2015-02-23

Magnetic spin structures in epitaxial BiFeO{sub 3} single layer and an epitaxial BaTiO{sub 3}/BiFeO{sub 3} multilayer thin film have been studied by means of nuclear resonant scattering of synchrotron radiation. We demonstrate a spin reorientation in the 15 × [BaTiO{sub 3}/BiFeO{sub 3}] multilayer compared to the single BiFeO{sub 3} thin film. Whereas in the BiFeO{sub 3} film, the net magnetic moment m{sup →} lies in the (1–10) plane, identical to the bulk, m{sup →} in the multilayer points to different polar and azimuthal directions. This spin reorientation indicates that strain and interfaces play a significant role in tuning the magnetic spin order.more » Furthermore, large difference in the magnetic field dependence of the magnetoelectric coefficient observed between the BiFeO{sub 3} single layer and multilayer can be associated with this magnetic spin reorientation.« less

Magnetic properties of sputtered Permalloy/molybdenum multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romera, M.; Ciudad, D.; Maicas, M.

2011-10-15

In this work, we report the magnetic properties of sputtered Permalloy (Py: Ni{sub 80}Fe{sub 20})/molybdenum (Mo) multilayer thin films. We show that it is possible to maintain a low coercivity and a high permeability in thick sputtered Py films when reducing the out-of-plane component of the anisotropy by inserting thin film spacers of a non-magnetic material like Mo. For these kind of multilayers, we have found coercivities which are close to those for single layer films with no out-of-plane anisotropy. The coercivity is also dependent on the number of layers exhibiting a minimum value when each single Py layer hasmore » a thickness close to the transition thickness between Neel and Bloch domain walls.« less

Transfer matrix approach for the Kerr and Faraday rotation in layered nanostructures.

PubMed

Széchenyi, Gábor; Vigh, Máté; Kormányos, Andor; Cserti, József

2016-09-21

To study the optical rotation of the polarization of light incident on multilayer systems consisting of atomically thin conductors and dielectric multilayers we present a general method based on transfer matrices. The transfer matrix of the atomically thin conducting layer is obtained using the Maxwell equations. We derive expressions for the Kerr (Faraday) rotation angle and for the ellipticity of the reflected (transmitted) light as a function of the incident angle and polarization of the light. The method is demonstrated by calculating the Kerr (Faraday) angle for bilayer graphene in the quantum anomalous Hall state placed on the top of dielectric multilayers. The optical conductivity of the bilayer graphene is calculated in the framework of a four-band model.

The stability of the epitaxially introduced metastable metallic structures of thin layers and multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cadeville, M.C.

Among the very large number of metallic thin films, sandwiches and multilayers which have been elaborated by epitaxy on various single crystalline substrates during the last decade, few new structures are reported. Limiting to the case of 3d metals, one finds with a great confidence bcc Cobalt, possibly bee Nickel and a non-compact hexagonal (hp) iron. Moreover structures existing at high temperature under ambient pressure are epitaxially stabilized at room temperature (RT) like fcc Cobalt, fcc Iron, fcc and bcc Manganese. The hcp iron which is stable under high pressure at RT would not be epitaxially stabilized at ambient pressuremore » conversely to first findings. The critical thickness of the metastable phase is generally limited to some monolayers in thin films, being slightly increased in sandwiches or multilayers, even if the phenomenological wetting criterion to build superlattices is not satisfied. No increased magnetic moment has been found up to now in the expanded lattices, contrary to band structure calculation predictions. 56 refs.« less

Sensing of contaminants in potable water using TiO{sub 2} functional film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akshatha, N.; Poonia, Monika; Gupta, R. K., E-mail: raj@pilani.bits-pilani.ac.in

2016-04-13

The piezoelectric based quartz crystal microbalance is employed for sensing contaminants in potable water. A spin coated thin layer of TiO{sub 2} nanoparticles was formed at the sensing area of a 5 MHz AT-cut quartz wafer. The thin film of TiO{sub 2} nanoparticles forms a mesoporous functional layer for the trapping of water borne contaminants. The morphology of the thin film of TiO{sub 2} nanoparticles was studied using field emission scanning electron microscope (FESEM). The surface morphology of the TiO{sub 2} nanoparticles reveals the mesoporous structures indicating large number of defects and porous sites. Such film was employed for the detectionmore » of water borne contaminants by detecting the piezoelectric response from a quartz crystal microbalance. We found the film to be very sensitive to the contaminants. The minimum detection limit was found to be 330 ppb. The effect of surface recharging was also studied by altering the physical conditions so that the film can be used for repetitive usage.« less

Investigation of porosity and heterojunction effects of a mesoporous hematite electrode on photoelectrochemical water splitting.

PubMed

Liu, Jingling; Shahid, Muhammad; Ko, Young-Seon; Kim, Eunchul; Ahn, Tae Kyu; Park, Jong Hyeok; Kwon, Young-Uk

2013-06-28

In this paper, we report the porosity and heterojunction effects of hematite (α-Fe2O3) on the photoelectrochemical (PEC) water splitting properties. The worm-like mesoporous hematite thin films (MHFs) with a pore size of ~9 nm and a wall thickness of ~5 nm were successfully obtained through the self-assembly process. MHFs formed on FTO showed much better PEC properties than those of nonporous hematite thin films (NP-HF) owing to the suppression of charge recombination. The PEC data of MHFs under front and back illumination conditions indicated that the porous structure allows the diffusion of electrolyte deep inside the MHF increasing the number of holes to be utilized in the water oxidation reaction. A heterojunction structure was formed by introducing a thin layer of SnO2 (~15 nm in thickness) between the MHF and FTO for a dramatically enhanced PEC response, which is attributed to the efficient electron transfer. Our spectroscopic and electrochemical data show that the SnO2 layer functions as an efficient electron transmitter, but does not affect the recombination kinetics of MHFs.

Fabrication and characterization of WO3/Ag/WO3 multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes

PubMed Central

2012-01-01

The dielectric/metal/dielectric multilayer is suitable for a transparent electrode because of its high-optical and high-electrical properties; however, it is fabricated by an expensive and inefficient multistep vacuum process. We present a WO3/Ag/WO3 (WAW) multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes (PLEDs). This WAW multilayer not only has high transmittance and low resistance but also can be easily and rapidly fabricated. We devised a novel method to deposit a thin WO3 layer by a solution process in an air environment. A tungstic acid solution was prepared from an aqueous solution of Na2WO4 and then converted to WO3 nanoparticles (NPs) by a thermal treatment. Thin WO3 NP layers form WAW multilayer with a thermal-evaporated Ag layer, and they improve the transmittance of the WAW multilayer because of its high transmittance and refractive index. Moreover, the surface of the WO3 layer is homogeneous and flat with low roughness because of the WO3 NP generation from the tungstic acid solution without aggregation. We performed optical simulation and experiments, and the optimized WAW multilayer had a high transmittance of 85% with a sheet resistance of 4 Ω/sq. Finally, PLEDs based on the WAW multilayer anode achieved a maximum luminance of 35,550 cd/m2 at 8 V, and this result implies that the solution-processed WAW multilayer is appropriate for use as a transparent anode in PLEDs. PMID:22587669

Fabrication and characterization of WO3/Ag/WO3 multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes.

PubMed

Jeon, Kangmin; Youn, Hongseok; Kim, Seongbeom; Shin, Seongbeom; Yang, Minyang

2012-05-15

The dielectric/metal/dielectric multilayer is suitable for a transparent electrode because of its high-optical and high-electrical properties; however, it is fabricated by an expensive and inefficient multistep vacuum process. We present a WO3/Ag/WO3 (WAW) multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes (PLEDs). This WAW multilayer not only has high transmittance and low resistance but also can be easily and rapidly fabricated. We devised a novel method to deposit a thin WO3 layer by a solution process in an air environment. A tungstic acid solution was prepared from an aqueous solution of Na2WO4 and then converted to WO3 nanoparticles (NPs) by a thermal treatment. Thin WO3 NP layers form WAW multilayer with a thermal-evaporated Ag layer, and they improve the transmittance of the WAW multilayer because of its high transmittance and refractive index. Moreover, the surface of the WO3 layer is homogeneous and flat with low roughness because of the WO3 NP generation from the tungstic acid solution without aggregation. We performed optical simulation and experiments, and the optimized WAW multilayer had a high transmittance of 85% with a sheet resistance of 4 Ω/sq. Finally, PLEDs based on the WAW multilayer anode achieved a maximum luminance of 35,550 cd/m2 at 8 V, and this result implies that the solution-processed WAW multilayer is appropriate for use as a transparent anode in PLEDs.

Reactive multilayers fabricated by vapor deposition. A critical review

DOE PAGES

Adams, D. P.

2014-10-02

The reactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In our critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, withmore » most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In later sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.« less

Effect of magnetization boundary condition on cavity magnon polariton of YIG thin film.

PubMed

Jiang, H H; Xiao, Y; Hu, C M; Guo, H; Xia, K

2018-06-22

Motivated by recent studies of cavity magnon polariton (CMP), we extended a previous theoretical work to generalize microwave transmission calculation with various magnetization boundary condition of YIG thin film embedded in cavity. It is found that numerical implementation given in this paper can be easily applied to other magnetization boundary condition and extended to magnetic multilayers. Numerical results show that ferromagnetic resonance mode of microwave transmission spectrum, which is absent in previous calculation, can be recovered by altering the pinning condition of surface spins. The demonstrated reliability of our theory opens attractive perspectives for studying CMP of thin film with complicated surface magnetization distribution and magnetic multilayers.

Properties of thin silver films with different thickness

NASA Astrophysics Data System (ADS)

Zhao, Pei; Su, Weitao; Wang, Reng; Xu, Xiaofeng; Zhang, Fengshan

2009-01-01

In order to investigate optical properties of silver films with different film thickness, multilayer composed of thin silver film sandwiched between ZnS films are sputtered on the float glass. The crystal structures, optical and electrical properties of films are characterized by various techniques, such as X-ray diffraction (XRD), spectrum analysis, etc. The optical constants of thin silver film are calculated by fitting the transmittance ( T) and reflectance ( R) spectrum of the multilayer. Electrical and optical properties of silver films thinner than 6.2 nm exhibit sharp change. However, variation becomes slow as film thickness is larger than 6.2 nm. The experimental results indicate that 6.2 nm is the optimum thickness for properties of silver.

Effect of magnetization boundary condition on cavity magnon polariton of YIG thin film

NASA Astrophysics Data System (ADS)

Jiang, H. H.; Xiao, Y.; Hu, C. M.; Guo, H.; Xia, K.

2018-06-01

Motivated by recent studies of cavity magnon polariton (CMP), we extended a previous theoretical work to generalize microwave transmission calculation with various magnetization boundary condition of YIG thin film embedded in cavity. It is found that numerical implementation given in this paper can be easily applied to other magnetization boundary condition and extended to magnetic multilayers. Numerical results show that ferromagnetic resonance mode of microwave transmission spectrum, which is absent in previous calculation, can be recovered by altering the pinning condition of surface spins. The demonstrated reliability of our theory opens attractive perspectives for studying CMP of thin film with complicated surface magnetization distribution and magnetic multilayers.

Ti{sub 2}AlN thin films synthesized by annealing of (Ti+Al)/AlN multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cabioch, Thierry, E-mail: Thierry.cabioch@univ-poitiers.fr; Alkazaz, Malaz; Beaufort, Marie-France

2016-08-15

Highlights: • Epitaxial thin films of the MAX phase Ti{sub 2}AlN are obtained by thermal annealing. • A new metastable (Ti,Al,N) solid solution with the structure of α-T is evidenced. • The formation of the MAX phase occurs at low temperature (600 °C). - Abstract: Single-phase Ti{sub 2}AlN thin films were obtained by annealing in vacuum of (Ti + Al)/AlN multilayers deposited at room temperature by magnetron sputtering onto single-crystalline (0001) 4H-SiC and (0001) Al{sub 2}O{sub 3} substrates. In-situ X-ray diffraction experiments combined with ex-situ cross-sectional transmission electron microscopy observations reveal that interdiffusion processes occur in the multilayer at amore » temperature of ∼400 °C leading to the formation of a (Ti, Al, N) solid solution, having the hexagonal structure of α-Ti, whereas the formation of Ti{sub 2}AlN occurs at 550–600 °C. Highly oriented (0002) Ti{sub 2}AlN thin films can be obtained after an annealing at 750 °C.« less

Solution-processed phase-change VO(2) metamaterials from colloidal vanadium oxide (VO(x)) nanocrystals.

PubMed

Paik, Taejong; Hong, Sung-Hoon; Gaulding, E Ashley; Caglayan, Humeyra; Gordon, Thomas R; Engheta, Nader; Kagan, Cherie R; Murray, Christopher B

2014-01-28

We demonstrate thermally switchable VO2 metamaterials fabricated using solution-processable colloidal nanocrystals (NCs). Vanadium oxide (VOx) NCs are synthesized through a nonhydrolytic reaction and deposited from stable colloidal dispersions to form NC thin films. Rapid thermal annealing transforms the VOx NC thin films into monoclinic, nanocrystalline VO2 thin films that show a sharp, reversible metal-insulator phase transition. Introduction of precise concentrations of tungsten dopings into the colloidal VOx NCs enables the still sharp phase transition of the VO2 thin films to be tuned to lower temperatures as the doping level increases. We fabricate "smart", differentially doped, multilayered VO2 films to program the phase and therefore the metal-insulator behavior of constituent vertically structured layers with temperature. With increasing temperature, we tailored the optical response of multilayered films in the near-IR and IR regions from that of a strong light absorber, in a metal-insulator structure, to that of a Drude-like reflector, characteristic of a pure metallic structure. We demonstrate that nanocrystal-based nanoimprinting can be employed to pattern multilayered subwavelength nanostructures, such as three-dimensional VO2 nanopillar arrays, that exhibit plasmonic dipolar responses tunable with a temperature change.

Fabrication of Co3O4 mesoporous thin films by using cobalt/chitosan precursor on fluorine-doped tin oxide glass

NASA Astrophysics Data System (ADS)

Yang, Hui-Chia; Tsai, Jung-Che

2017-06-01

For the development of high-performance and low-cost electrode materials, many alternative materials have been fabricated by various groups. Among these materials, Co3O4 has been demonstrated to be a promising candidate for pseudocapacitors because of its low potential environmental pollution, low cost, and extremely high theoretical specific capacitance. Chitosan, a linear polysaccharide produced by the deacetylation of chitin, is a nontoxic, tissue-compatible polymeric biomaterial. It is usually used to eliminate or filter the heavy metals in wastewater. That is, chitosan can act as a deliverer of metal ions and a nanostructure constructer of metals (or metal oxides). In this study, a facile approach is developed to synthesize mesoporous cobalt oxide thin films on fluorine-doped tin oxide (FTO)-coated glass with environmentally friendly chitosan, which chelates cobalt ions.

Thermal conductivity of mesoporous films measured by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Stoib, B.; Filser, S.; Petermann, N.; Wiggers, H.; Stutzmann, M.; Brandt, M. S.

2014-04-01

We measure the in-plane thermal conductance of mesoporous Ge and SiGe thin films using the Raman-shift method and, based on a finite differences simulation accounting for the geometry of the sample, extract the in-plane thermal conductivity. For a suspended thin film of laser-sintered SiGe nanoparticles doped with phosphorus, we find an effective in-plane thermal conductivity of 0.05 W/m K in vacuum for a temperature difference of 400 K and a mean temperature of 500 K. Under similar conditions, the effective in-plane thermal conductivity of a laser-sintered undoped Ge nanoparticle film is 0.5 W/m K. Accounting for a porosity of approximately 50%, the normalized thermal conductivities are 0.1 W/m K and 1 W/m K, respectively. The thermoelectric performance is discussed, considering that the electrical in-plane conductivity is also affected by the mesoporosity.

Stress Compensating Multilayers

NASA Technical Reports Server (NTRS)

Broadway, David M.; Ramsey, Brian D.; O'dell, Stephen; Gurgew, Danielle

2017-01-01

We present in-situ stress measurement results for single and multilayer thin-films deposited by magnetron sputtering. In particular, we report on the influence of the material interfaces on the ensuing stress in both the transient and steady-state regimes of film growth. This behavior is used to determine the appropriate thicknesses of the constituent layers that will result in a net tensile stress in multilayers composed of various material combinations. These multilayers can then be used to compensate the compressive integrated stress in single and multilayer EUV and x-ray optical coatings. The use of multilayers to compensate the integrated stress might be advantageous because, unlike single layers of chromium, the roughness is not expected to increase with the total thickness of the multilayer. In this paper, we demonstrate the technique for W/Si and Mo/Si multilayers and discuss its application to other material combinations.

Roll-to-Roll sputtered ITO/Cu/ITO multilayer electrode for flexible, transparent thin film heaters and electrochromic applications.

PubMed

Park, Sung-Hyun; Lee, Sang-Mok; Ko, Eun-Hye; Kim, Tae-Ho; Nah, Yoon-Chae; Lee, Sang-Jin; Lee, Jae Heung; Kim, Han-Ki

2016-09-22

We fabricate high-performance, flexible, transparent electrochromic (EC) films and thin film heaters (TFHs) on an ITO/Cu/ITO (ICI) multilayer electrode prepared by continuous roll-to-roll (RTR) sputtering of ITO and Cu targets. The RTR-sputtered ICI multilayer on a 700 mm wide PET substrate at room temperature exhibits a sheet resistance of 11.8 Ω/square and optical transmittance of 73.9%, which are acceptable for the fabrication of flexible and transparent EC films and TFHs. The effect of the Cu interlayer thickness on the electrical and optical properties of the ICI multilayer was investigated in detail. The bending and cycling fatigue tests demonstrate that the RTR-sputtered ICI multilayer was more flexible than a single ITO film because of high strain failure of the Cu interlayer. The flexible and transparent EC films and TFHs fabricated on the ICI electrode show better performances than reference EC films and TFHs with a single ITO electrode. Therefore, the RTR-sputtered ICI multilayer is the best substitute for the conventional ITO film electrode in order to realize flexible, transparent, cost-effective and large-area EC devices and TFHs that can be used as flexible and smart windows.

Roll-to-Roll sputtered ITO/Cu/ITO multilayer electrode for flexible, transparent thin film heaters and electrochromic applications

NASA Astrophysics Data System (ADS)

Park, Sung-Hyun; Lee, Sang-Mok; Ko, Eun-Hye; Kim, Tae-Ho; Nah, Yoon-Chae; Lee, Sang-Jin; Lee, Jae Heung; Kim, Han-Ki

2016-09-01

We fabricate high-performance, flexible, transparent electrochromic (EC) films and thin film heaters (TFHs) on an ITO/Cu/ITO (ICI) multilayer electrode prepared by continuous roll-to-roll (RTR) sputtering of ITO and Cu targets. The RTR-sputtered ICI multilayer on a 700 mm wide PET substrate at room temperature exhibits a sheet resistance of 11.8 Ω/square and optical transmittance of 73.9%, which are acceptable for the fabrication of flexible and transparent EC films and TFHs. The effect of the Cu interlayer thickness on the electrical and optical properties of the ICI multilayer was investigated in detail. The bending and cycling fatigue tests demonstrate that the RTR-sputtered ICI multilayer was more flexible than a single ITO film because of high strain failure of the Cu interlayer. The flexible and transparent EC films and TFHs fabricated on the ICI electrode show better performances than reference EC films and TFHs with a single ITO electrode. Therefore, the RTR-sputtered ICI multilayer is the best substitute for the conventional ITO film electrode in order to realize flexible, transparent, cost-effective and large-area EC devices and TFHs that can be used as flexible and smart windows.

Roll-to-Roll sputtered ITO/Cu/ITO multilayer electrode for flexible, transparent thin film heaters and electrochromic applications

PubMed Central

Park, Sung-Hyun; Lee, Sang-Mok; Ko, Eun-Hye; Kim, Tae-Ho; Nah, Yoon-Chae; Lee, Sang-Jin; Lee, Jae Heung; Kim, Han-Ki

2016-01-01

We fabricate high-performance, flexible, transparent electrochromic (EC) films and thin film heaters (TFHs) on an ITO/Cu/ITO (ICI) multilayer electrode prepared by continuous roll-to-roll (RTR) sputtering of ITO and Cu targets. The RTR-sputtered ICI multilayer on a 700 mm wide PET substrate at room temperature exhibits a sheet resistance of 11.8 Ω/square and optical transmittance of 73.9%, which are acceptable for the fabrication of flexible and transparent EC films and TFHs. The effect of the Cu interlayer thickness on the electrical and optical properties of the ICI multilayer was investigated in detail. The bending and cycling fatigue tests demonstrate that the RTR-sputtered ICI multilayer was more flexible than a single ITO film because of high strain failure of the Cu interlayer. The flexible and transparent EC films and TFHs fabricated on the ICI electrode show better performances than reference EC films and TFHs with a single ITO electrode. Therefore, the RTR-sputtered ICI multilayer is the best substitute for the conventional ITO film electrode in order to realize flexible, transparent, cost-effective and large-area EC devices and TFHs that can be used as flexible and smart windows. PMID:27653830

Direct-Write Laser Grayscale Lithography for Multilayer Lead Zirconate Titanate Thin Films.

PubMed

Benoit, Robert R; Jordan, Delaney M; Smith, Gabriel L; Polcawich, Ronald G; Bedair, Sarah S; Potrepka, Daniel M

2018-05-01

Direct-write laser grayscale lithography has been used to facilitate a single-step patterning technique for multilayer lead zirconate titanate (PZT) thin films. A 2.55- -thick photoresist was patterned with a direct-write laser. The intensity of the laser was varied to create both tiered and sloped structures that are subsequently transferred into multilayer PZT(52/48) stacks using a single Ar ion-mill etch. Traditional processing requires a separate photolithography step and an ion mill etch for each layer of the substrate, which can be costly and time consuming. The novel process allows access to buried electrode layers in the multilayer stack in a single photolithography step. The grayscale process was demonstrated on three 150-mm diameter Si substrates configured with a 0.5- -thick SiO 2 elastic layer, a base electrode of Pt/TiO 2 , and a stack of four PZT(52/48) thin films of either 0.25- thickness per layer or 0.50- thickness per layer, and using either Pt or IrO 2 electrodes above and below each layer. Stacked capacitor structures were patterned and results will be reported on the ferroelectric and electromechanical properties using various wiring configurations and compared to comparable single layer PZT configurations.

The effect of annealing on structural and optical properties of α-Fe2O3/CdS/α-Fe2O3 multilayer heterostructures

NASA Astrophysics Data System (ADS)

Saleem, M.; Durrani, S. M. A.; Saheb, N.; Al-Kuhaili, M. F.; Bakhtiari, I. A.

2014-11-01

Multilayered thin film heterostructures of α-Fe2O3/CdS/α-Fe2O3 were prepared through physical vapor deposition. Each α-Fe2O3 layer was deposited by e-beam evaporation of iron in an oxygen atmosphere. The CdS layer was deposited by thermal evaporation in a vacuum. The effect of post annealing of multilayered thin films in air in the temperature range 250 °C to 450 °C was investigated. Structural characterization indicated the growth of the α-Fe2O3 phase with a polycrystalline structure without any CdS crystalline phase. As-deposited multilayer heterostructures were amorphous and transformed into polycrystalline upon annealing. The surface modification of the films during annealing was revealed by scanning electron microscopy. Spectrophotometric measurements were used to determine the optical properties, including the transmittance, absorbance, and band gap. All the films had both direct as well as indirect band gaps.

"Shrink-to-fit" superhydrophobicity: thermally-induced microscale wrinkling of thin hydrophobic multilayers fabricated on flexible shrink-wrap substrates.

PubMed

Manna, Uttam; Carter, Matthew C D; Lynn, David M

2013-06-11

An approach to the design of flexible superhydrophobic surfaces based on thermally induced wrinkling of thin, hydrophobic polymer multilayers on heat-shrinkable polymer films is reported. This approach exploits shrinking processes common to "heat-shrink" plastics, and can thus be used to create "shrink-to-fit" superhydrophobic coatings on complex surfaces, manipulate the dimensions and densities of patterned features, and promote heat-activated repair of full-thickness defects. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metastable and equilibrium phase formation in sputter-deposited Ti/Al multilayer thin films

NASA Astrophysics Data System (ADS)

Lucadamo, G.; Barmak, K.; Lavoie, C.; Cabral, C., Jr.; Michaelsen, C.

2002-06-01

The sequence and kinetics of metastable and equilibrium phase formation in sputter deposited multilayer thin films was investigated by combining in situ synchrotron x-ray diffraction (XRD) with ex situ electron diffraction and differential scanning calorimetry (DSC). The sequence included both cubic and tetragonal modifications of the equilibrium TiAl3 crystal structure. Values for the formation activation energies of the various phases in the sequence were determined using the XRD and DSC data obtained here, as well as activation energy data reported in the literature.

Thin film solar energy collector

DOEpatents

Aykan, Kamran; Farrauto, Robert J.; Jefferson, Clinton F.; Lanam, Richard D.

1983-11-22

A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

Nano-crystalline thin and nano-particulate thick TiO{sub 2} layer: Cost effective sequential deposition and study on dye sensitized solar cell characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, P.; Sengupta, D.; CSIR-Central Mechanical Engineering Research Institute, Academy of Scientific and Innovative Research

Highlights: • Thin TiO{sub 2} layer is deposited on conducting substrate using sol–gel based dip coating. • TiO{sub 2} nano-particles are synthesized using hydrothermal route. • Thick TiO{sub 2} particulate layer is deposited on prepared thin layer. • Dye sensitized solar cells are made using thin and thick layer based photo-anode. • Introduction of thin layer in particulate photo-anode improves the cell efficiency. - Abstract: A compact thin TiO{sub 2} passivation layer is introduced between the mesoporous TiO{sub 2} nano-particulate layer and the conducting glass substrate to prepare photo-anode for dye-sensitized solar cell (DSSC). In order to understand the effectmore » of passivation layer, other two DSSCs are also developed separately using TiO{sub 2} nano-particulate and compact thin film based photo-anodes. Nano-particles are prepared using hydrothermal synthesis route and the compact passivation layer is prepared by simply dip coating the precursor sol prepared through wet chemical route. The TiO{sub 2} compact layer and the nano-particles are characterised in terms of their micro-structural features and phase formation behavior. It is found that introduction of a compact TiO{sub 2} layer in between the mesoporous TiO{sub 2} nano-particulate layer and the conducting substrate improves the solar to electric conversion efficiency of the fabricated cell. The dense thin passivation layer is supposed to enhance the photo-excited electron transfer and prevent the recombination of photo-excited electrons.« less

Thin-film designs by simulated annealing

NASA Astrophysics Data System (ADS)

Boudet, T.; Chaton, P.; Herault, L.; Gonon, G.; Jouanet, L.; Keller, P.

1996-11-01

With the increasing power of computers, new methods in synthesis of optical multilayer systems have appeared. Among these, the simulated-annealing algorithm has proved its efficiency in several fields of physics. We propose to show its performances in the field of optical multilayer systems through different filter designs.

High Transparent and Conductive TiO2/Ag/TiO2 Multilayer Electrode Films Deposited on Sapphire Substrate

NASA Astrophysics Data System (ADS)

Loka, Chadrasekhar; Moon, Sung Whan; Choi, YiSik; Lee, Kee-Sun

2018-03-01

Transparent conducting oxides attract intense interests due to its diverse industrial applications. In this study, we report sapphire substrate-based TiO2/Ag/TiO2 (TAT) multilayer structure of indium-free transparent conductive multilayer coatings. The TAT thin films were deposited at room temperature on sapphire substrates and a rigorous analysis has been presented on the electrical and optical properties of the films as a function of Ag thickness. The optical and electrical properties were mainly controlled by the Ag mid-layer thickness of the TAT tri-layer. The TAT films showed high luminous transmittance 84% at 550 nm along with noteworthy low electrical resistance 3.65 × 10-5 Ω-cm and sheet resistance of 3.77 Ω/square, which is better are than those of amorphous ITO films and any sapphire-based dielectric/metal/dielectric multilayer stack. The carrier concentration of the films was increased with respect to Ag thickness. We obtained highest Hackke's figure of merit 43.97 × 10-3 Ω-1 from the TAT multilayer thin film with a 16 nm thick Ag mid-layer.

Finite element analysis of multilayer DEAP stack-actuators

NASA Astrophysics Data System (ADS)

Kuhring, Stefan; Uhlenbusch, Dominik; Hoffstadt, Thorben; Maas, Jürgen

2015-04-01

Dielectric elastomers (DE) are thin polymer films belonging to the class of electroactive polymers (EAP). They are coated with compliant and conductive electrodes on each side, which make them performing a relative high amount of deformation with considerable force generation under the influence of an electric field. Because the realization of high electric fields with a limited voltage level requests single layer polymer films to be very thin, novel multilayer actuators are utilized to increase the absolute displacement and force. In case of a multilayer stack-actuator, many actuator films are mechanically stacked in series and electrically connected in parallel. Because there are different ways to design such a stack-actuator, this contribution considers an optimization of some design parameters using the finite element analysis (FEA), whereby the behavior and the actuation of a multilayer dielectric electroactive polymer (DEAP) stack-actuator can be improved. To describe the material behavior, first different material models are compared and necessary material parameters are identified by experiments. Furthermore, a FEA model of a DEAP film is presented, which is expanded to a multilayer DEAP stack-actuator model. Finally, the results of the FEA are discussed and conclusions for design rules of optimized stack-actuators are outlined.

Application of low-coherence interferometry for in situ nondestructive evaluation of thin and thick multilayered transparent composites

NASA Astrophysics Data System (ADS)

Khomenko, Anton; Cloud, Gary Lee; Haq, Mahmoodul

2015-12-01

Multilayered transparent composites having laminates with polymer interlayers and backing sheets are commonly used in a wide range of applications where visibility, transparency, impact resistance, and safety are essential. Manufacturing flaws or damage during operation can seriously compromise both safety and performance. Most fabrication defects are not discernible until after the entire multilayered transparent composite assembly has been completed, and in-the-field inspection for damage is a problem not yet solved. A robust and reliable nondestructive evaluation (NDE) technique is needed to evaluate structural integrity and identify defects that result from manufacturing issues as well as in-service damage arising from extreme environmental conditions in addition to normal mechanical and thermal loads. Current optical techniques have limited applicability for NDE of such structures. This work presents a technique that employs a modified interferometer utilizing a laser diode or femtosecond fiber laser source to acquire in situ defect depth location inside a thin or thick multilayered transparent composite, respectively. The technique successfully located various defects inside examined composites. The results show great potential of the technique for defect detection, location, and identification in multilayered transparent composites.

Ultra-thin layer packaging for implantable electronic devices

NASA Astrophysics Data System (ADS)

Hogg, A.; Aellen, T.; Uhl, S.; Graf, B.; Keppner, H.; Tardy, Y.; Burger, J.

2013-07-01

State of the art packaging for long-term implantable electronic devices generally uses reliable metal and glass housings; however, these are limited in the miniaturization potential and cost reduction. This paper focuses on the development of biocompatible hermetic thin-film packaging based on poly-para-xylylene (Parylene-C) and silicon oxide (SiOx) multilayers for smart implantable microelectromechanical systems (MEMS) devices. For the fabrication, a combined Parylene/SiOx single-chamber deposition system was developed. Topological aspects of multilayers were characterized by atomic force microscopy and scanning electron microscopy. Material compositions and layer interfaces were analyzed by Fourier transform infrared spectrometry and x-ray photoelectron spectroscopy. To evaluate the multilayer corrosion protection, water vapor permeation was investigated using a calcium mirror test. The calcium mirror test shows very low water permeation rates of 2 × 10-3 g m-2 day-1 (23 °C, 45% RH) for a 4.7 µm multilayer, which is equivalent to a 1.9 mm pure Parylene-C coating. According to the packaging standard MIL-STD-883, the helium gas tightness was investigated. These helium permeation measurements predict that a multilayer of 10 µm achieves the hermeticity acceptance criterion required for long-term implantable medical devices.

Investigation into the energy-absorbing properties of multilayered circular thin-walled tube

NASA Astrophysics Data System (ADS)

Qi, Aidong; Liu, Chuanhua; Hu, Gongli; Gu, Hongjun

2002-05-01

With the rise in collision accident and the increase in requirement for resistance of blastproof structures in recent years, people attach much importance to the research and application of energy-absorbing device. In this paper the author calculates the specific strength, the specific hardness and ultimate internal force of a circular thin-walled tube by theoretic calculations, discusses the feasibility of using circular thin-walled tube as an energy-absorbing element, analyzes the energy-absorbing properties and the energy-absorbing mechanism through the energy-absorbing experiments using various materials and forms of arrangement, reaches the conclusion that the load-bearing capacity and energy-absorbing properties of multilayered tubes are superior to that of single tube, and puts forward the concept of 'grading tube'.

A diffusion-reaction scheme for modeling ignition and self-propagating reactions in Al/CuO multilayered thin films

NASA Astrophysics Data System (ADS)

Lahiner, Guillaume; Nicollet, Andrea; Zapata, James; Marín, Lorena; Richard, Nicolas; Rouhani, Mehdi Djafari; Rossi, Carole; Estève, Alain

2017-10-01

Thermite multilayered films have the potential to be used as local high intensity heat sources for a variety of applications. Improving the ability of researchers to more rapidly develop Micro Electro Mechanical Systems devices based on thermite multilayer films requires predictive modeling in which an understanding of the relationship between the properties (ignition and flame propagation), the multilayer structure and composition (bilayer thicknesses, ratio of reactants, and nature of interfaces), and aspects related to integration (substrate conductivity and ignition apparatus) is achieved. Assembling all these aspects, this work proposes an original 2D diffusion-reaction modeling framework to predict the ignition threshold and reaction dynamics of Al/CuO multilayered thin films. This model takes into consideration that CuO first decomposes into Cu2O, and then, released oxygen diffuses across the Cu2O and Al2O3 layers before reacting with pure Al to form Al2O3. This model is experimentally validated from ignition and flame velocity data acquired on Al/CuO multilayers deposited on a Kapton layer. This paper discusses, for the first time, the importance of determining the ceiling temperature above which the multilayers disintegrate, possibly before their complete combustion, thus severely impacting the reaction front velocity and energy release. This work provides a set of heating surface areas to obtain the best ignition conditions, i.e., with minimal ignition power, as a function of the substrate type.

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiMarco, Brian N.; Troian-Gautier, Ludovic; Sampaio, Renato N.

Two sensitizers, [Ru(bpy) 2 (dcb)] 2+ ( RuC ) and [Ru(bpy) 2 (dpb)] 2+ ( RuP ), were anchored to mesoporous TiO 2 thin films and utilized to sensitize the reaction of TiO 2 electrons with oxidized triphenylamines to visible light in CH 3 CN electrolytes.

Synthesis of polycarbonate-r-polyethylene glycol copolymer for templated synthesis of mesoporous TiO2 films.

PubMed

Patel, Rajkumar; Kim, Jinkyu; Lee, Chang Soo; Kim, Jong Hak

2014-12-01

We synthesized a novel polycarbonate Z-r-polyethylene glycol (PCZ-r-PEG) copolymer by solution polycondensation. Successful synthesis of PCZ-r-PEG copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC), and transmission electron microscopy (TEM). PCZ-r-PEG copolymer was used as a structure-directing agent for fabrication of mesoporous thin film containing a titanium dioxide (TiO2) layer. To control the porosity of the resultant inorganic layer, the ratio of titanium(IV) isopropoxide (TTIP) to PCZ-r-PEG copolymer was varied. The structure and porosity of the resulting mesoporous films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Mesoporous TiO2 films fabricated on an F-doped tin oxide (FTO) surface were used as photoanodes for quasi-solid-state dye-sensitized solar cells (qssDSSCs). The highest efficiency achieved was 3.3% at 100 mW/cm2 for a film thickness of 750 nm, which is high considering the thickness of TiO2 film, indicating the importance of the structure-directing agent.

Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications

PubMed Central

Skuza, J. R.; Scott, D. W.; Mundle, R. M.; Pradhan, A. K.

2016-01-01

We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5–10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT. PMID:26884225

Preparation of multilayered nanocrystalline thin films with composition-modulated interfaces

NASA Astrophysics Data System (ADS)

Biro, D.; Barna, P. B.; Székely, L.; Geszti, O.; Hattori, T.; Devenyi, A.

2008-06-01

The properties of multilayer thin film structures depend on the morphology and structure of interfaces. A broad interface, in which the composition is varying, can enhance, e.g., the hardness of multilayer thin films. In the present experiments multilayers of TiAlN and CrN as well as TiAlN, CrN and MoS 2 were studied by using unbalanced magnetron sputter sources. The sputter sources were arranged side by side on an arc. This arrangement permits development of a transition zone between the layers, where the composition changes continuously. The multilayer system was deposited by one-fold oscillating movement of substrates in front of sputter sources. Thicknesses of layers could be changed both by oscillation frequency and by the power applied to sputter sources. Ti/Al: 50/50 at%, pure chromium and MoS 2 targets were used in the sputter sources. The depositions were performed in an Ar-N 2 mixture at 0.22 Pa working pressure. The sputtering power of the TiAl source was feed-back adjusted in fuzzy-logic mode in order to avoid fluctuation of the TiAl target sputter rate due to poisoning of the target surface. Structure characterization of films deposited on <1 0 0> Si wafers covered by thermally grown SiO 2 was performed by cross-sectional transmission electron microscopy. At first a 100 nm thick Cr base layer was deposited on the substrate to improve adhesion, which was followed by a CrN transition layer. The CrN transition layer was followed by a 100 nm thick TiAlN/CrN multilayer system. The TiAlN/CrN/MoS 2 multilayer system was deposited on the surface of this underlayer system. The underlayer systems Cr, CrN and TiAlN/CrN were crystalline with columnar structure according to the morphology of zone T of the structure zone models. The column boundaries contained segregated phases showing up in the under-focused TEM images. The surface of the underlayer system was wavy due to dome-shaped columns. The nanometer-scaled TiAlN/CrN/MoS 2 multilayer system followed this waviness. Crystallinity of the TiAlN and CrN layers in the multilayer system decreases with increasing thickness of the MoS 2 layer.

Fabrication of stable, wide-bandgap thin films of Mg, Zn and O

DOEpatents

Katiyar, Ram S.; Bhattacharya, Pijush; Das, Rasmi R.

2006-07-25

A stable, wide-bandgap (approximately 6 eV) ZnO/MgO multilayer thin film is fabricated using pulsed-laser deposition on c-plane Al₂O₃ substrates. Layers of ZnO alternate with layers of MgO. The thickness of MgO is a constant of approximately 1 nm; the thicknesses of ZnO layers vary from approximately 0.75 to 2.5 nm. Abrupt structural transitions from hexagonal to cubic phase follow a decrease in the thickness of ZnO sublayers within this range. The band gap of the thin films is also influenced by the crystalline structure of multilayer stacks. Thin films with hexagonal and cubic structure have band-gap values of 3.5 and 6 eV, respectively. In the hexagonal phase, Mg content of the films is approximately 40%; in the cubic phase Mg content is approximately 60%. The thin films are stable and their structural and optical properties are unaffected by annealing at 750.degree. C.

Giant negative electrocaloric effect in PbZrO3/0.88BaTiO3-0.12Bi(Mg1/2,Ti1/2)O3 multilayered composite ferroelectric thin film for solid-state refrigeration

NASA Astrophysics Data System (ADS)

Huang, D.; Wang, J. B.; Zhong, X. L.; Li, B.; Zhang, Y.; Jin, C.; Zheng, D. F.; Meng, X. J.

2017-11-01

A giant negative electrocaloric (EC) effect in a PbZrO3/(0.88BaTiO3-0.12 Bi(Mg1/2,Ti1/2)O3) (PZ/(BT-BMT)) multilayered composite ferroelectric (MCFE) thin film which is grown on Pt(111)/Ti/SiO2/Si(100) substrates by the sol-gel method is investigated in this work. The negative EC effect in the PZ/(BMT-BT) MCFE thin film is greatly higher than that in the PZ AFE thin film with an adiabatic temperature change (ATC) ΔT = 1.5 K. The ATC ΔT of the PZ/(BMT-BT) MCFE thin film is -32 K under the applied electric field change ΔE = 1151 kV/cm. The result is conducive to enhance the EC refrigeration efficiency greatly.

X-ray beamsplitter

DOEpatents

Ceglio, N.M.; Stearns, D.G.; Hawryluk, A.M.; Barbee, T.W. Jr.

1987-08-07

An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5--50 pairs of alternate Mo/Si layers with a period of 20--250 A. The support membrane is 10--200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window. 6 figs.

X-ray beamsplitter

DOEpatents

Ceglio, Natale M.; Stearns, Daniel S.; Hawryluk, Andrew M.; Barbee, Jr., Troy W.

1989-01-01

An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5-50 pairs of alternate Mo/Si layers with a period of 20-250 A. The support membrane is 10-200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window.

Nanosecond Surface Microdischarges in Multilayer Structures

NASA Astrophysics Data System (ADS)

Dubinov, A. E.; Lyubimtseva, V. A.

2018-05-01

Multilayer structures in which nanosecond surface microdischarges are generated have been developed, fabricated, and investigated. In these structures, layers are made in the form of thin transparent films, and a plasma discharge channel is formed in thin spacings between the layers. Passage of the discharge channel from one layer into the neighboring layer is implemented via pre-fabricated microholes. Images of microdischarges were obtained which confirmed that their plasma channels are formed according to the route assigned by the holes. The route may follow a fairly complex scheme and have self-intersection points and portions in which the electrons are bound to move in opposition to the electric field. In studying the shape of channels in multilayer strictures, the authors have found a new physical effect which lies in the azimuthal self-orientation of the discharge channel as it passes from one microhole to another.

Enhanced thermo-spin effects in iron-oxide/metal multilayers

NASA Astrophysics Data System (ADS)

Ramos, R.; Lucas, I.; Algarabel, P. A.; Morellón, L.; Uchida, K.; Saitoh, E.; Ibarra, M. R.

2018-06-01

Since the discovery of the spin Seebeck effect (SSE), much attention has been devoted to the study of the interaction between heat, spin, and charge in magnetic systems. The SSE refers to the generation of a spin current upon the application of a thermal gradient and detected by means of the inverse spin Hall effect. Conversely, the spin Peltier effect (SPE) refers to the generation of a heat current as a result of a spin current induced by the spin Hall effect. Here we report a strong enhancement of both the SSE and SPE in Fe3O4/Pt multilayered thin films at room temperature as a result of an increased thermo-spin conversion efficiency in the multilayers. These results open the possibility to design thin film heterostructures that may boost the application of thermal spin currents in spintronics.

Calibration of the Multi-Spectral Solar Telescope Array multilayer mirrors and XUV filters

NASA Technical Reports Server (NTRS)

Allen, Maxwell J.; Willis, Thomas D.; Kankelborg, Charles C.; O'Neal, Ray H.; Martinez-Galarce, Dennis S.; Deforest, Craig E.; Jackson, Lisa; Lindblom, Joakim; Walker, Arthur B. C., Jr.; Barbee, Troy W., Jr.

1993-01-01

The Multi-Spectral Solar Telescope Array (MSSTA), a rocket-borne solar observatory, was successfully flown in May, 1991, obtaining solar images in eight XUV and FUV bands with 12 compact multilayer telescopes. Extensive measurements have recently been carried out on the multilayer telescopes and thin film filters at the Stanford Synchrotron Radiation Laboratory. These measurements are the first high spectral resolution calibrations of the MSSTA instruments. Previous measurements and/or calculations of telescope throughputs have been confirmed with greater accuracy. Results are presented on Mo/Si multilayer bandpass changes with time and experimental potassium bromide and tellurium filters.

Unexpected resonant response in [Fe(001)/Cr(001)]10/MgO(001) multilayers in a magnetic field.

PubMed

Aliev, F G; Pryadun, V V; Snoeck, E

2009-01-23

We observed unexpected resonant response in [Fe/Cr]10 multilayers epitaxially grown on MgO(100) substrates which exists only when both ac current and dc magnetic field are simultaneously applied. The magnitude of the resonances is determined by the multilayer magnetization proving their intrinsic character. The reduction of interface epitaxy leads to nonlinear dependence of the magnitude of resonances on the alternating current density. We speculate that the existence of the interface transition zone could facilitate the subatomic vibrations in thin metallic films and multilayers grown on bulk insulating substrates.

The Effect of Pluronic 123 Surfactant concentration on The N2 Adsorption Capacity of Mesoporous Silica SBA-15: Dubinin-Astakhov Adsorption Isotherm Analysis

NASA Astrophysics Data System (ADS)

Dhaneswara, Donanta; Siti Agustina, A. A. A.; Dewantoro Adhy, P.; Delayori, Farhan; Fajar Fatriansyah, Jaka

2018-04-01

Mesoporous SBA-15 has been successfully synthesized at various concentration of Pluronic 123 surfactant (7mM, 50 mM, 54 mM, 60 mM and 66 mM) and the effect of these various concentrations on the N2 adsorption capacity has been investigated. The adsorption analysis was conducted using Dubinin-Astakhov isotherm model for multilayer adsorption phenomenon. It was found that etryat low concentration of Pluronic 123, the system exhibits type I adsorption isotherm while at high concentration, the system exhibits type IV adsorption with H1 hysteresis curve which indicates the existence of pores with cylindrical geometry, relatively uniform pore size and possibility of pore network effects. It also was found that, by using D-A isotherm model fitting, at 60 mM concentration of Pluronic 123, SBA-15 has the highest adsorption capacity which stands at 421 cm3/gram.

Exploring interface morphology of a deeply buried layer in periodic multilayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, Gangadhar; Srivastava, A. K.; Tiwari, M. K., E-mail: mktiwari@rrcat.gov.in

2016-06-27

Long-term durability of a thin film device is strongly correlated with the nature of interface structure associated between different constituent layers. Synthetic periodic multilayer structures are primarily employed as artificial X-ray Bragg reflectors in many applications, and their reflection efficiency is predominantly dictated by the nature of the buried interfaces between the different layers. Herein, we demonstrate the applicability of the combined analysis approach of the X-ray reflectivity and grazing incidence X-ray fluorescence measurements for the reliable and precise determination of a buried interface structure inside periodic X-ray multilayer structures. X-ray standing wave field (XSW) generated under Bragg reflection conditionmore » is used to probe the different constituent layers of the W- B{sub 4}C multilayer structure at 10 keV and 12 keV incident X-ray energies. Our results show that the XSW assisted fluorescence measurements are markedly sensitive to the location and interface morphology of a buried layer structure inside a periodic multilayer structure. The cross sectional transmission electron microscopy results obtained on the W-B{sub 4}C multilayer structure provide a deeper look on the overall reliability and accuracy of the XSW method. The method described here would also be applicable for nondestructive characterization of a wide range of thin film based semiconductor and optical devices.« less

Piezoelectric polymer multilayer on flexible substrate for energy harvesting.

PubMed

Zhang, Lei; Oh, Sharon Roslyn; Wong, Ting Chong; Tan, Chin Yaw; Yao, Kui

2013-09-01

A piezoelectric polymer multilayer structure formed on a flexible substrate is investigated for mechanical energy harvesting under bending mode. Analytical and numerical models are developed to clarify the effect of material parameters critical to the energy harvesting performance of the bending multilayer structure. It is shown that the maximum power is proportional to the square of the piezoelectric stress coefficient and the inverse of dielectric permittivity of the piezoelectric polymer. It is further found that a piezoelectric multilayer with thinner electrodes can generate more electric energy in bending mode. The effect of improved impedance matching in the multilayer polymer on energy output is remarkable. Comparisons between piezoelectric ceramic multilayers and polymer multilayers on flexible substrate are discussed. The fabrication of a P(VDF-TrFE) multilayer structure with a thin Al electrode layer is experimentally demonstrated by a scalable dip-coating process on a flexible aluminum substrate. The results indicate that it is feasible to produce a piezoelectric polymer multilayer structure on flexible substrate for harvesting mechanical energy applicable for many low-power electronics.

Development of high damage threshold multilayer thin film beam combiner for laser application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nand, Mangla, E-mail: mnand@rrcat.gov.in; Babita,; Jena, S.

2016-05-23

A polarized wavelength multiplexer with high laser induced damage threshold has been developed to combine two laser beam of high peak power in the visible region. The present wavelength multiplexer is a multilayer thin film device deposited by reactive electron beam evaporation. The developed device is capable of combining two p-polarized laser beams of peak power density of 1.7 GW/cm{sup 2} at an angle of incidence of 45°. High transmission (T> 90%) in high pass region and high reflection (R> 99%) in stop band region have been achieved.

Indentation-Induced Shear Band Formation in Thin-Film Multilayers

NASA Astrophysics Data System (ADS)

Bigelow, Shannon; Shen, Yu-Lin

2017-08-01

We report an exploratory investigation into the cause of shear band formation in multilayer thin-films subject to nanoindentation. The material system considered here is composed of alternating aluminum (Al) and silicon carbide (SiC) nanolayers, atop a silicon (Si) substrate. Finite element models are developed in an attempt to reproduce the shear banding phenomenon observed experimentally. By introducing strain softening into the material model for the hard SiC layers, shear bands can be seen to emerge from the indentation site in the finite element analysis. Broad implications, along with possible directions for future work, are discussed.

Development of high damage threshold multilayer thin film beam combiner for laser application

NASA Astrophysics Data System (ADS)

Nand, Mangla; Babita, Jena, S.; Tokas, R. B.; Rajput, P.; Mukharjee, C.; Thakur, S.; Jha, S. N.; Sahoo, N. K.

2016-05-01

A polarized wavelength multiplexer with high laser induced damage threshold has been developed to combine two laser beam of high peak power in the visible region. The present wavelength multiplexer is a multilayer thin film device deposited by reactive electron beam evaporation. The developed device is capable of combining two p-polarized laser beams of peak power density of 1.7 GW/cm2 at an angle of incidence of 45°. High transmission (T> 90%) in high pass region and high reflection (R> 99%) in stop band region have been achieved.

Layer-by-layer grown scalable redox-active ruthenium-based molecular multilayer thin films for electrochemical applications and beyond.

PubMed

Kaliginedi, Veerabhadrarao; Ozawa, Hiroaki; Kuzume, Akiyoshi; Maharajan, Sivarajakumar; Pobelov, Ilya V; Kwon, Nam Hee; Mohos, Miklos; Broekmann, Peter; Fromm, Katharina M; Haga, Masa-aki; Wandlowski, Thomas

2015-11-14

Here we report the first study on the electrochemical energy storage application of a surface-immobilized ruthenium complex multilayer thin film with anion storage capability. We employed a novel dinuclear ruthenium complex with tetrapodal anchoring groups to build well-ordered redox-active multilayer coatings on an indium tin oxide (ITO) surface using a layer-by-layer self-assembly process. Cyclic voltammetry (CV), UV-Visible (UV-Vis) and Raman spectroscopy showed a linear increase of peak current, absorbance and Raman intensities, respectively with the number of layers. These results indicate the formation of well-ordered multilayers of the ruthenium complex on ITO, which is further supported by the X-ray photoelectron spectroscopy analysis. The thickness of the layers can be controlled with nanometer precision. In particular, the thickest layer studied (65 molecular layers and approx. 120 nm thick) demonstrated fast electrochemical oxidation/reduction, indicating a very low attenuation of the charge transfer within the multilayer. In situ-UV-Vis and resonance Raman spectroscopy results demonstrated the reversible electrochromic/redox behavior of the ruthenium complex multilayered films on ITO with respect to the electrode potential, which is an ideal prerequisite for e.g. smart electrochemical energy storage applications. Galvanostatic charge-discharge experiments demonstrated a pseudocapacitor behavior of the multilayer film with a good specific capacitance of 92.2 F g(-1) at a current density of 10 μA cm(-2) and an excellent cycling stability. As demonstrated in our prototypical experiments, the fine control of physicochemical properties at nanometer scale, relatively good stability of layers under ambient conditions makes the multilayer coatings of this type an excellent material for e.g. electrochemical energy storage, as interlayers in inverted bulk heterojunction solar cell applications and as functional components in molecular electronics applications.

Effect of hydrogen on the device performance and stability characteristics of amorphous InGaZnO thin-film transistors with a SiO2/SiNx/SiO2 buffer

NASA Astrophysics Data System (ADS)

Han, Ki-Lim; Ok, Kyung-Chul; Cho, Hyeon-Su; Oh, Saeroonter; Park, Jin-Seong

2017-08-01

We investigate the influence of the multi-layered buffer consisting of SiO2/SiNx/SiO2 on amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs). The multi-layered buffer inhibits permeation of water from flexible plastic substrates and prevents degradation of overlying organic layers. The a-IGZO TFTs with a multi-layered buffer suffer less positive bias temperature stress instability compared to the device with a single SiO2 buffer layer after annealing at 250 °C. Hydrogen from the SiNx layer diffuses into the active layer and reduces electron trapping at loosely bound oxygen defects near the SiO2/a-IGZO interface. Quantitative analysis shows that a hydrogen density of 1.85 × 1021 cm-3 is beneficial to reliability. However, the multi-layered buffer device annealed at 350 °C resulted in conductive characteristics due to the excess carrier concentration from the higher hydrogen density of 2.12 × 1021 cm-3.

Highly stable thin film transistors using multilayer channel structure

NASA Astrophysics Data System (ADS)

Nayak, Pradipta K.; Wang, Zhenwei; Anjum, D. H.; Hedhili, M. N.; Alshareef, H. N.

2015-03-01

We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60 °C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

Preparation of highly ordered mesoporous Al2O3/TiO2 and its application in dye-sensitized solar cells.

PubMed

Kim, Jae-Yup; Kang, Soon Hyung; Kim, Hyun Sik; Sung, Yung-Eun

2010-02-16

Highly ordered mesoporous Al(2)O(3)/TiO(2) was prepared by sol-gel reaction and evaporation-induced self-assembly (EISA) for use in dye-sensitized solar cells. The prepared materials had two-dimensional, hexagonal pore structures with anatase crystalline phases. The average pore size of mesoporous Al(2)O(3)/TiO(2) remained uniform and in the range of 6.33-6.58 nm while the Brunauer-Emmett-Teller (BET) surface area varied from 181 to 212 m(2)/g with increasing the content of Al(2)O(3). The incorporation of Al content retarded crystallite growth, thereby decreasing crystallite size while simultaneously improving the uniformity of pore size and volume. The thin Al(2)O(3) layer was located mostly on the mesopore surface, as confirmed by X-ray photoelectron spectroscopy (XPS). The Al(2)O(3) coating on the mesoporous TiO(2) film contributes to the essential energy barrier which blocks the charge recombination process in dye-sensitized solar cells. Mesoporous Al(2)O(3)/TiO(2) (1 mol % Al(2)O(3)) exhibited enhanced power conversion efficiency (V(oc) = 0.74 V, J(sc) = 15.31 mA/cm(2), fill factor = 57%, efficiency = 6.50%) compared to pure mesoporous TiO(2) (V(oc) = 0.72 V, J(sc) = 16.03 mA/cm(2), fill factor = 51%, efficiency = 5.88%). Therefore, the power conversion efficiency was improved by approximately 10.5%. In particular, the increase in V(oc) and fill factor resulted from the inhibition of charge recombination and the improvement of pore structure.

Nanocrystalline mesoporous SMO thin films prepared by sol gel process for MEMS-based hydrogen sensor

NASA Astrophysics Data System (ADS)

Gong, Jianwei; Fei, Weifeng; Seal, Sudipta; Chen, Quanfang

2004-01-01

MEMS based SnO2 gas sensor with sol gel synthesized mesoporous nanocrystalline (<10 nm) semiconductor thin (100~150 nm) film has been recently developed. The SnO2 nano film is fabricated with the combination of polymeric sol gel chemistry with block copolymers used for structure directing agents. The novel hydrogen sensor has a fast response time (1s) and quick recovery time (3s), as well as good sensitivity (about 90%), comparing to other hydrogen sensors developed. The improved capabilities are credited to the large surface to volume ratio of gas sensing thin film with nano sized porous surface topology, which can greatly increase the sensitivity even at relatively low working temperature. The gas sensing film is deposited onto a thin dielectric membrane of low thermal conductivity, which provides good thermal isolation between substrate and the gas-sensitive heated area on the membrane. In this way the power consumption can be kept very low. Since the fabrication process is completely compatible with IC industry, it makes mass production possible and greatly reduces the cost. The working temperature of the new sensor can be reduced as low as 100°C. The low working temperature posse advantages such as lower power consumption, lower thermal induced signal shift as well as safe detection in certain environments where temperature is strictly limited.

Freestanding two-dimensional Ni(OH)2 thin sheets assembled by 3D nanoflake array as basic building units for supercapacitor electrode materials.

PubMed

Song, Dianmei; Zhu, Jikui; Xuan, Liying; Zhao, Chenglan; Xie, Li; Chen, Lingyun

2018-01-01

Freestanding two dimensional (2D) porous nanostructures have great potential in electrical energy storage. In the present work, we reported the first synthesis of two-dimensional (2D) β-Ni(OH) 2 thin sheets (CQU-Chen-Ni-O-H-1) assembled by 3D nanoflake array as basic building units under acid condition by direct hydrothermal decomposition of the mixed solution of nickel nitrate (Ni(NO 3 ) 2 ) and acetic acid (CH 3 COOH, AA). The unique 3D nanoflake array assembled mesoporous 2D structures endow the thin sheets with a high specific capacitance of 1.78Fcm -2 (1747.5Fg -1 ) at the current density of 1.02mAcm -2 and good rate capability of 67.4% retain from 1.02 to 10.2mAcm -2 . The corresponding assembled asymmetric supercapacitor (ASC) achieves (CQU-Chen-Ni-O-H-1//active carbon (AC)) a high voltage of 1.8V and an energy density of 23.45Whkg -1 with a maximum power density of 9kWkg -1 , as well as cycability with 93.6% capacitance retention after 10,000 cycles. These results show the mesoporous thin sheets have great potential for SCs and other energy storage devices. Copyright © 2017 Elsevier Inc. All rights reserved.

Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

PubMed Central

2014-01-01

To provide a front transparent electrode for use in highly efficient hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, porous flat layer and micro-patterns of zinc oxide (ZnO) nanoparticle (NP) layers were prepared through ultraviolet nanoimprint lithography (UV-NIL) and deposited on Al-doped ZnO (AZO) layers. Through this, it was found that a porous micro-pattern of ZnO NPs dispersed in resin can optimize the light-trapping pattern, with the efficiency of solar cells based on patterned or flat mesoporous ZnO layers increased by 27% and 12%, respectively. PMID:25276101

Thin-Film Power Transformers

NASA Technical Reports Server (NTRS)

Katti, Romney R.

1995-01-01

Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

Stoichiometry and thickness dependence of superconducting properties of niobium nitride thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beebe, Melissa R., E-mail: mrbeebe@email.wm.edu; Beringer, Douglas B.; Burton, Matthew C.

2016-03-15

The current technology used in linear particle accelerators is based on superconducting radio frequency (SRF) cavities fabricated from bulk niobium (Nb), which have smaller surface resistance and therefore dissipate less energy than traditional nonsuperconducting copper cavities. Using bulk Nb for the cavities has several advantages, which are discussed elsewhere; however, such SRF cavities have a material-dependent accelerating gradient limit. In order to overcome this fundamental limit, a multilayered coating has been proposed using layers of insulating and superconducting material applied to the interior surface of the cavity. The key to this multilayered model is to use superconducting thin films tomore » exploit the potential field enhancement when these films are thinner than their London penetration depth. Such field enhancement has been demonstrated in MgB{sub 2} thin films; here, the authors consider films of another type-II superconductor, niobium nitride (NbN). The authors present their work correlating stoichiometry and superconducting properties in NbN thin films and discuss the thickness dependence of their superconducting properties, which is important for their potential use in the proposed multilayer structure. While there are some previous studies on the relationship between stoichiometry and critical temperature T{sub C}, the authors are the first to report on the correlation between stoichiometry and the lower critical field H{sub C1}.« less

Binary metal oxide nanoparticle incorporated composite multilayer thin films for sono-photocatalytic degradation of organic pollutants

NASA Astrophysics Data System (ADS)

Gokul, Paramasivam; Vinoth, Ramalingam; Neppolian, Bernaurdshaw; Anandhakumar, Sundaramurthy

2017-10-01

We report reduced graphene oxide (rGO) supported binary metal oxide (CuO-TiO2/rGO) nanoparticle (NP) incorporated multilayer thin films based on Layer-by-Layer (LbL) assembly for enhanced sono-photocatalytic degradation of methyl orange under exposure to UV radiation. Multilayer thin films were fabricated on glass and quartz slides, and investigated using scanning electron microscopy and UV-vis spectroscopy. The loading of catalyst NPs on the film resulted in the change of morphology of the film from smooth to rough with uniformly distributed NPs on the surface. The growth of the control and NP incorporated films followed a linear regime as a function of number of layers. The%degradation of methyl orange as a function of time was investigated by UV-vis spectroscopy and total organic carbon (TOC) measurements. Complete degradation of methyl orange was achieved within 13 h. The amount of NP loading in the film significantly influenced the%degradation of methyl orange. Catalyst reusability studies revealed that the catalyst thin films could be repeatedly used for up to five times without any change in photocatalytic activity of the films. The findings of the present study support that the binary metal oxide catalyst films reported here are very useful for continuous systems, and thus, making it an option for scale up.

Thermoelectric properties of Zn4Sb3/CeFe(4-x)CoxSb12 nano-layered superlattices modified by MeV Si ion beam

NASA Astrophysics Data System (ADS)

Budak, S.; Guner, S.; Minamisawa, R. A.; Muntele, C. I.; Ila, D.

2014-08-01

We prepared multilayers of superlattice thin film system with 50 periodic alternating nano-layers of semiconducting half-Heusler β-Zn4Sb3 and skutterudite CeFe2Co2Sb12 compound thin films using ion beam assisted deposition (IBAD) with Au layers deposited on both sides as metal contacts. The deposited multilayer thin films have alternating layers about 5 nm thick. The total thickness of the multilayer system is 275 nm. The superlattices were then bombarded by 5 MeV Si ion at six different fluences to form nano-cluster structures. The film thicknesses and composition were monitored by Rutherford backscattering spectrometry (RBS) before and after MeV ion bombardment. We have measured the thermoelectric efficiency, Figure of Merit ZT, of the fabricated device by measuring the cross plane thermal conductivity by the 3rd harmonic (3ω) method, the cross plane Seebeck coefficient, and the electrical conductivity using the van der Pauw method before and after the MeV ion bombardments. We reached the remarkable thermoelectric Figure of Merit results at optimal fluences.

Quantitative evaluation of sputtering induced surface roughness and its influence on AES depth profiles of polycrystalline Ni/Cu multilayer thin films

NASA Astrophysics Data System (ADS)

Yan, X. L.; Coetsee, E.; Wang, J. Y.; Swart, H. C.; Terblans, J. J.

2017-07-01

The polycrystalline Ni/Cu multilayer thin films consisting of 8 alternating layers of Ni and Cu were deposited on a SiO2 substrate by means of electron beam evaporation in a high vacuum. Concentration-depth profiles of the as-deposited multilayered Ni/Cu thin films were determined with Auger electron spectroscopy (AES) in combination with Ar+ ion sputtering, under various bombardment conditions with the samples been stationary as well as rotating in some cases. The Mixing-Roughness-Information depth (MRI) model used for the fittings of the concentration-depth profiles accounts for the interface broadening of the experimental depth profiling. The interface broadening incorporates the effects of atomic mixing, surface roughness and information depth of the Auger electrons. The roughness values extracted from the MRI model fitting of the depth profiling data agrees well with those measured by atomic force microscopy (AFM). The ion sputtering induced surface roughness during the depth profiling was accordingly quantitatively evaluated from the fitted MRI parameters with sample rotation and stationary conditions. The depth resolutions of the AES depth profiles were derived directly from the values determined by the fitting parameters in the MRI model.

Multi-layer thin-film electrolytes for metal supported solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Haydn, Markus; Ortner, Kai; Franco, Thomas; Uhlenbruck, Sven; Menzler, Norbert H.; Stöver, Detlev; Bräuer, Günter; Venskutonis, Andreas; Sigl, Lorenz S.; Buchkremer, Hans-Peter; Vaßen, Robert

2014-06-01

A key to the development of metal-supported solid oxide fuel cells (MSCs) is the manufacturing of gas-tight thin-film electrolytes, which separate the cathode from the anode. This paper focuses the electrolyte manufacturing on the basis of 8YSZ (8 mol.-% Y2O3 stabilized ZrO2). The electrolyte layers are applied by a physical vapor deposition (PVD) gas flow sputtering (GFS) process. The gas-tightness of the electrolyte is significantly improved when sequential oxidic and metallic thin-film multi-layers are deposited, which interrupt the columnar grain structure of single-layer electrolytes. Such electrolytes with two or eight oxide/metal layers and a total thickness of about 4 μm obtain leakage rates of less than 3 × 10-4 hPa dm3 s-1 cm-2 (Δp: 100 hPa) at room temperature and therefore fulfill the gas tightness requirements. They are also highly tolerant with respect to surface flaws and particulate impurities which can be present on the graded anode underground. MSC cell tests with double-layer and multilayer electrolytes feature high power densities more than 1.4 W cm-2 at 850 °C and underline the high potential of MSC cells.

Innovative soft magnetic multilayers with enhanced in-plane anisotropy and ferromagnetic resonance frequency for integrated RF passive devices

NASA Astrophysics Data System (ADS)

Falub, Claudiu V.; Bless, Martin; Hida, Rachid; MeduÅa, Mojmír; Ammann, Arnold

2018-04-01

We present an innovative, economical method for manufacturing soft magnetic materials that may pave the way for integrated thin film magnetic cores with dramatically improved properties. Soft magnetic multilayered thin films based on the Fe-28%Co20%B (at.%) and Co-4.5%Ta4%Zr (at.%) amorphous alloys are deposited on 8" bare Si and Si/200nm-thermal-SiO2 wafers in an industrial, high-throughput Evatec LLS EVO II magnetron sputtering system. The multilayers consist of stacks of alternating 80-nm-thick ferromagnetic layers and 4-nm-thick Al2O3 dielectric interlayers. Since in our dynamic sputter system the substrate cage rotates continuously, such that the substrates face different targets alternatively, each ferromagnetic sublayer in the multilayer consists of a fine structure comprising alternating CoTaZr and FeCoB nanolayers with very sharp interfaces. We adjust the thickness of these individual nanolayers between 0.5 and 1.5 nm by changing the cage rotation speed and the power of each gun, which is an excellent mode to engineer new, composite ferromagnetic materials. Using X-ray reflectometry (XRR) we reveal that the interfaces between the FeCoB and CoTaZr nanolayers are perfectly smooth with roughness of 0.2-0.3 nm. Kerr magnetometry and B-H looper measurements for the as-deposited samples show that the coercivity of these thin films is very low, 0.2-0.3 Oe, and gradually scales up with the thickness of FeCoB nanolayers, i.e. with the increase of the overall Fe content from 0 % (e.g. CoTaZr-based multilayers) to 52 % (e.g. FeCoB-based multilayers). We explain this trend in the random anisotropy model, based on considerations of grain size growth, as revealed by glancing angle X-ray diffraction (GAXRD), but also because of the increase of magnetostriction with the increase of Fe content as shown by B-H looper measurements performed on strained wafers. The unexpected enhancement of the in-plane anisotropy field from 18.3 Oe and 25.8 Oe for the conventional CoTaZr- and FeCoB-based multilayers, respectively, up to ˜48 Oe for the nanostructured multilayers with FeCoB/CoTaZr nano-bilayers is explained based on interface anisotropy contribution. These novel soft magnetic multilayers, with enhanced in-plane anisotropy, allow operation at higher frequencies, as revealed by broadband (between 100 MHz and 10 GHz) RF measurements that exhibit a classical Landau-Lifschitz-Gilbert (LLG) behavior.

Origin of colossal dielectric response of CaCu3Ti4O12 studied by using CaTiO3/CaCu3Ti4O12/CaTiO3 multilayer thin films

NASA Astrophysics Data System (ADS)

Mitsugi, Masakazu; Asanuma, Shutaro; Uesu, Yoshiaki; Fukunaga, Mamoru; Kobayashi, Wataru; Terasaki, Ichiro

2007-06-01

To elucidate the origin of the colossal dielectric response (CDR) of CaCu3Ti4O12 (CCTO), multilayer thin films of CCTO interposed in insulating CaTiO3 (CTO) were synthesized using a pulsed laser deposition technique. The capacitance C of CTO/CCTO/CTO films with different layer thicknesses is measured. After removing the capacitance of CTO by extrapolating C to zero CTO thickness, the real part of dielectric constant of CCTO is estimated to be 329-435, which is much smaller than the reported value for CCTO thin films. This fact indicates that the CDR of CCTO is extrinsic and originates from an internal barrier layer capacitor.

Optimized thin film coatings for passive radiative cooling applications

NASA Astrophysics Data System (ADS)

Naghshine, Babak B.; Saboonchi, Ahmad

2018-03-01

Passive radiative cooling is a very interesting method, which lays on low atmospheric downward radiation within 8-13 μm waveband at dry climates. Various thin film multilayer structures have been investigated in numerous experimental studies, in order to find better coatings to exploit the full potential of this method. However, theoretical works are handful and limited. In this paper, the Simulated Annealing and Genetic Algorithm are used to optimize a thin film multilayer structure for passive radiative cooling applications. Spectral radiative properties are calculated through the matrix formulation. Considering a wide range of materials, 30 high-potential convective shields are suggested. According to the calculations, cooling can be possible even under direct sunlight, using the introduced shields. Moreover, a few water-soluble materials are studied for the first time and the results show that, a KBr substrate coated by a thin CaF2 or polyethylene film can is very close to an ideal coating for passive radiative cooling at night.

A fabrication and characterictics of microbolometer detectors using VOx/ZnO/VOx multilayer thin film processing

NASA Astrophysics Data System (ADS)

Han, Myung-Soo; Kim, Dae Hyeon; Ko, Hang Ju; Shin, Jae Chul; Kim, Hyo Jin; Kim, Do Gun

2014-06-01

In this work, a novel fabrication method for VOx-ZnO multilayers with mixed phase of the VO2 and V2O3 through the diffusion of oxygen by annealing at low temperature is presented. A stable sandwich structure of a VOx/ZnO/VOx multilayer was deposited at room temperature, through the oxygen gas flow rate, by RF sputtering system, and the mixed phase was formed through oxygen diffusion by annealing at O2 atmosphere. The results show that the single phase like multilayer formed by this process has a high TCR of more than -2.5%/K and low resistance of about 100 kohm at room temperature. XRD results for the as-deposited VOx/ZnO/VOx multilayer.

FIBER AND INTEGRATED OPTICS: Reflection of electromagnetic radiation from a multilayer waveguide structure with an absorbing metal layer

NASA Astrophysics Data System (ADS)

Chernushich, A. P.; Shkerdin, G. N.; Shukin, Yu M.

1992-10-01

The angular distribution of the reflection coefficient of an asymmetric multilayer planar structure containing a thin metal film and a planar optical waveguide has been found by accurate numerical calculations. There are resonances in the reflection coefficient associated with hybrid modes of the structure. The cases of strong and weak coupling of the surface polariton modes with the waveguide modes are discussed. The results of the numerical analysis agree with solutions of Maxwell's equations for a multilayer planar structure.

Artificial multilayers and nanomagnetic materials.

PubMed

Shinjo, Teruya

2013-01-01

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.

A Bottle-around-a-Ship Method To Generate Hollow Thin-Shelled Particles Containing Encapsulated Iron Species with Application to the Environmental Decontamination of Chlorinated Compounds.

PubMed

Su, Yang; Wang, Yingqing; Owoseni, Olasehinde; Zhang, Yueheng; Gamliel, David Pierce; Valla, Julia A; McPherson, Gary L; John, Vijay T

2018-04-25

Thin-shelled hollow silica particles are synthesized using an aerosol-based process where the concentration of a silica precursor tetraethyl orthosilicate (TEOS) determines the shell thickness. The synthesis involves a novel concept of the salt bridging of an iron salt, FeCl 3 , to a cationic surfactant, cetyltrimethylammonium bromide (CTAB), which modulates the templating effect of the surfactant on silica porosity. The salt bridging leads to a sequestration of the surfactant in the interior of the droplet with the formation of a dense silica shell around the organic material. Subsequent calcination consistently results in hollow particles with encapsulated iron oxides. Control of the TEOS levels leads to the generation of ultrathin-shelled (∼10 nm) particles which become susceptible to rupture upon exposure to ultrasound. The dense silica shell that is formed is impervious to entry of chemical species. Mesoporosity is restored to the shell through desilication and reassembly, again using CTAB as a template. The mesoporous-shelled hollow particles show good reactivity toward the reductive dichlorination of trichloroethylene (TCE), indicating access of TCE to the particle interior. The ordered mesoporous thin-shelled particles containing active iron species are viable systems for chemical reaction and catalysis.

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials

DTIC Science & Technology

2016-04-27

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials PI Maria received support to construct a physical...vapor deposition (PVD) system that combines electron beam (e- beam) evaporation, magnetron sputtering, pulsed laser ablation, and ion-assisted deposition ...The instrumentation enables clean, uniform, and rapid deposition of a wide variety of metallic, semiconducting, and ceramic thin films with

Optical coating on a corrugated surface to align the polarization of an unpolarized wave without loss

NASA Astrophysics Data System (ADS)

Jen, Yi Jun

2017-12-01

A multilayer comprising birefringent thin films is devised to present to function as a polarization beam splitter and waveplate simultaneously. By arranging such a multilayer on a right triangle-shaped corrugated surface, a polarizer is realized to align the randomly oscillating electric field of an unpolarized wave into a linear polarized wave without loss.

Layered ultra-thin coherent structures used as electrical resistors having low-temperature coefficient of resistivity

DOEpatents

Werner, T.R.; Falco, C.M.; Schuller, I.K.

1982-08-31

A thin film resistor having a controlled temperature coefficient of resistance (TCR) ranging from negative to positive degrees kelvin and having relatively high resistivity. The resistor is a multilayer superlattice crystal containing a plurality of alternating, ultra-thin layers of two different metals. TCR is varied by controlling the thickness of the individual layers. The resistor can be readily prepared by methods compatible with thin film circuitry manufacturing techniques.

Analyzing adsorption characteristics of CO2, N2 and H2O in MCM-41 silica by molecular simulation

NASA Astrophysics Data System (ADS)

Chang, Shing-Cheng; Chien, Shih-Yao; Chen, Chieh-Li; Chen, Cha'o.-Kuang

2015-03-01

The adsorption characteristics of carbon dioxide, nitrogen and water molecules in MCM-41 mesoporous molecular sieve have been investigated by the molecular simulation. We evaluate the pressure-adsorption isotherms and adsorption density profiles under variant gas pressure, operating temperature and mesopore radius of MCM-41 by the grand canonical Monte Carlo simulation. According to the calculated adsorption energy distributions, the adsorption mechanisms of gas in MCM-41 are mainly divided into three types, namely "surface adsorption" on the pore wall, "multilayer adsorption" on the adsorbed gas molecules and "molecular self-aggregation" near the pore center. In addition, the adsorption characteristics of water molecules in MCM-41 are found to be quite different from those of carbon dioxide and nitrogen due to the hydrogen bonds effect. The results indicate that the MCM-41 is practicable in engineering application for the capture, storage, and re-use of water molecules, since it is temperature-sensitive and can achieve significant adsorption loadings within a small range of pressure values via the capillary condensation phenomena.

Multifunctional Hybrid Multilayer Gate Dielectrics with Tunable Surface Energy for Ultralow-Power Organic and Amorphous Oxide Thin-Film Transistors.

PubMed

Byun, Hye-Ran; You, Eun-Ah; Ha, Young-Geun

2017-03-01

For large-area, printable, and flexible electronic applications using advanced semiconductors, novel dielectric materials with excellent capacitance, insulating property, thermal stability, and mechanical flexibility need to be developed to achieve high-performance, ultralow-voltage operation of thin-film transistors (TFTs). In this work, we first report on the facile fabrication of multifunctional hybrid multilayer gate dielectrics with tunable surface energy via a low-temperature solution-process to produce ultralow-voltage organic and amorphous oxide TFTs. The hybrid multilayer dielectric materials are constructed by iteratively stacking bifunctional phosphonic acid-based self-assembled monolayers combined with ultrathin high-k oxide layers. The nanoscopic thickness-controllable hybrid dielectrics exhibit the superior capacitance (up to 970 nF/cm 2 ), insulating property (leakage current densities <10 -7 A/cm 2 ), and thermal stability (up to 300 °C) as well as smooth surfaces (root-mean-square roughness <0.35 nm). In addition, the surface energy of the hybrid multilayer dielectrics are easily changed by switching between mono- and bifunctional phosphonic acid-based self-assembled monolayers for compatible fabrication with both organic and amorphous oxide semiconductors. Consequently, the hybrid multilayer dielectrics integrated into TFTs reveal their excellent dielectric functions to achieve high-performance, ultralow-voltage operation (< ± 2 V) for both organic and amorphous oxide TFTs. Because of the easily tunable surface energy, the multifunctional hybrid multilayer dielectrics can also be adapted for various organic and inorganic semiconductors, and metal gates in other device configurations, thus allowing diverse advanced electronic applications including ultralow-power and large-area electronic devices.

Electrochemical Analysis of Conducting Polymer Thin Films

PubMed Central

Vyas, Ritesh N.; Wang, Bin

2010-01-01

Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting polymer, poly(p-phenylene vinylene) (PPV), in the preparation of a stable thin film via the LbL method. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize the ionic conductivity of the PPV multilayer films. The ionic conductivity of the films has been found to be dependent on the polymerization temperature. The film conductivity can be fitted to a modified Randle’s circuit. The circuit equivalent calculations are performed to provide the diffusion coefficient values. PMID:20480052

Interface Properties of Atomic-Layer-Deposited Al2O3 Thin Films on Ultraviolet/Ozone-Treated Multilayer MoS2 Crystals.

PubMed

Park, Seonyoung; Kim, Seong Yeoul; Choi, Yura; Kim, Myungjun; Shin, Hyunjung; Kim, Jiyoung; Choi, Woong

2016-05-11

We report the interface properties of atomic-layer-deposited Al2O3 thin films on ultraviolet/ozone (UV/O3)-treated multilayer MoS2 crystals. The formation of S-O bonds on MoS2 after low-power UV/O3 treatment increased the surface energy, allowing the subsequent deposition of uniform Al2O3 thin films. The capacitance-voltage measurement of Au-Al2O3-MoS2 metal oxide semiconductor capacitors indicated n-type MoS2 with an electron density of ∼10(17) cm(-3) and a minimum interface trap density of ∼10(11) cm(-2) eV(-1). These results demonstrate the possibility of forming a high-quality Al2O3-MoS2 interface by proper UV/O3 treatment, providing important implications for their integration into field-effect transistors.

Brilliant iridescence of Morpho butterfly wing scales is due to both a thin film lower lamina and a multilayered upper lamina.

PubMed

Giraldo, M A; Stavenga, D G

2016-05-01

Butterflies belonging to the nymphalid subfamily, Morphinae, are famous for their brilliant blue wing coloration and iridescence. These striking optical phenomena are commonly explained as to originate from multilayer reflections by the ridges of the wing scales. Because the lower lamina of the scales of related nymphalid butterflies, the Nymphalinae, plays a dominant role in the wing coloration, by acting as a thin film reflector, we investigated single blue scales of three characteristic Morpho species: M. epistrophus, M. helenor and M. cypris. The experimental data obtained by spectrophotometry, scatterometry and scanning electron microscopy demonstrated that also in the Morpho genus the lower lamina of both the cover and ground scales acts as an optical thin film reflector, contributing importantly to the blue structural coloration of the wings. Melanin pigment has a contrast-enhancing function in a sub-class of ground scales.

Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures

DOE PAGES

Song, Tiancheng; Cai, Xinghan; Tu, Matisse Wei-Yuan; ...

2018-05-03

Magnetic multilayer devices that exploit magnetoresistance are the backbone of magnetic sensing and data storage technologies. Here, we report multiple-spin-filter magnetic tunnel junctions (sf-MTJs) based on van der Waals (vdW) heterostructures in which atomically thin chromium triiodide (CrI3) acts as a spin-filter tunnel barrier sandwiched between graphene contacts. We demonstrate tunneling magnetoresistance which is drastically enhanced with increasing CrI 3 layer thickness, reaching a record 19,000% for magnetic multilayer structures using four-layer sf-MTJs at low temperatures. Using magnetic circular dichroism measurements, we attribute these effects to the intrinsic layer-by-layer antiferromagnetic ordering of the atomically thin CrI 3. In conclusion, ourmore » work reveals the possibility to push magnetic information storage to the atomically thin limit and highlights CrI 3 as a superlative magnetic tunnel barrier for vdW heterostructure spintronic devices.« less

Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Tiancheng; Cai, Xinghan; Tu, Matisse Wei-Yuan

Magnetic multilayer devices that exploit magnetoresistance are the backbone of magnetic sensing and data storage technologies. Here, we report multiple-spin-filter magnetic tunnel junctions (sf-MTJs) based on van der Waals (vdW) heterostructures in which atomically thin chromium triiodide (CrI3) acts as a spin-filter tunnel barrier sandwiched between graphene contacts. We demonstrate tunneling magnetoresistance which is drastically enhanced with increasing CrI 3 layer thickness, reaching a record 19,000% for magnetic multilayer structures using four-layer sf-MTJs at low temperatures. Using magnetic circular dichroism measurements, we attribute these effects to the intrinsic layer-by-layer antiferromagnetic ordering of the atomically thin CrI 3. In conclusion, ourmore » work reveals the possibility to push magnetic information storage to the atomically thin limit and highlights CrI 3 as a superlative magnetic tunnel barrier for vdW heterostructure spintronic devices.« less

Solid-state dewetting of magnetic binary multilayer thin films

NASA Astrophysics Data System (ADS)

Esterina, Ria; Liu, X. M.; Adeyeye, A. O.; Ross, C. A.; Choi, W. K.

2015-10-01

We examined solid-state dewetting behavior of magnetic multilayer thin film in both miscible (CoPd) and immiscible (CoAu) systems and found that CoPd and CoAu dewetting stages follow that of elemental materials. We established that CoPd alloy morphology and dewetting rate lie in between that of the elemental materials. Johnson-Mehl-Avrami analysis was utilized to extract the dewetting activation energy of CoPd. For CoAu, Au-rich particles and Co-rich particles are distinguishable and we are able to predict the interparticle spacings and particle densities for the particles that agree well with the experimental results. We also characterized the magnetic properties of CoPd and CoAu nanoparticles.

AND/R: Advanced neutron diffractometer/reflectometer for investigation of thin films and multilayers for the life sciences

PubMed Central

Dura, Joseph A.; Pierce, Donald J.; Majkrzak, Charles F.; Maliszewskyj, Nicholas C.; McGillivray, Duncan J.; Lösche, Mathias; O'Donovan, Kevin V.; Mihailescu, Mihaela; Perez-Salas, Ursula; Worcester, David L.; White, Stephen H.

2011-01-01

An elastic neutron scattering instrument, the advanced neutron diffractometer/reflectometer (AND/R), has recently been commissioned at the National Institute of Standards and Technology Center for Neutron Research. The AND/R is the centerpiece of the Cold Neutrons for Biology and Technology partnership, which is dedicated to the structural characterization of thin films and multilayers of biological interest. The instrument is capable of measuring both specular and nonspecular reflectivity, as well as crystalline or semicrystalline diffraction at wave-vector transfers up to approximately 2.20 Å−1. A detailed description of this flexible instrument and its performance characteristics in various operating modes are given. PMID:21892232

Microsteganography on WS2 Monolayers Tailored by Direct Laser Painting.

PubMed

Venkatakrishnan, Ashwin; Chua, Hou; Tan, Pinxi; Hu, Zhenliang; Liu, Hongwei; Liu, Yanpeng; Carvalho, Alexandra; Lu, Junpeng; Sow, Chorng Haur

2017-01-24

We present scanning focused laser beam as a multipurpose tool to engineer the physical and chemical properties of WS 2 microflakes. For monolayers, the laser modification integrates oxygen into the WS 2 microflake, resulting in ∼9 times enhancement in the intensity of the fluorescence emission. This modification does not cause any morphology change, allowing "micro-encryption" of information that is only observable as fluorescence under excitation. The same focused laser also facilitates on demand thinning down of WS 2 multilayers into monolayers, turning them into fluorescence active components. With a scanning focused laser beam, micropatterns are readily created on WS 2 multilayers through selective thinning of specific regions on the flake.

Design guidelines for advanced LSI microcircuit packaging using thick film multilayer technology

NASA Technical Reports Server (NTRS)

Peckinpaugh, C. J.

1974-01-01

Ceramic multilayer circuitry results from the sequential build-up of two or more layers of pre-determined conductive interconnections separated by dielectric layers and fired at an elevated temperature to form a solidly fused structure. The resultant ceramic interconnect matrix is used as a base to mount active and passive devices and provide the necessary electrical interconnection to accomplish the desired electrical circuit. Many methods are known for developing multilevel conductor mechanisms such as multilayer printed circuits, welded wire matrices, flexible copper tape conductors, and thin and thick-film ceramic multilayers. Each method can be considered as a specialized field with each possessing its own particular set of benefits and problems. This design guide restricts itself to the art of design, fabrication and assembly of ceramic multilayer circuitry and the reliability of the end product.

Characteristics of high-k gate dielectric formed by the oxidation of sputtered Hf/Zr/Hf thin films on the Si substrate

NASA Astrophysics Data System (ADS)

Kim, H. D.; Roh, Y.; Lee, J. E.; Kang, H.-B.; Yang, C.-W.; Lee, N.-E.

2004-07-01

We have investigated the effects of high temperature annealing on the physical and electrical properties of multilayered high-k gate oxide [HfSixOy/HfO2/intermixed-layer(IL)/ZrO2/intermixed-layer(IL)/HfO2] in metal-oxide-semiconductor device. The multilayered high-k films were formed after oxidizing the Hf/Zr/Hf films deposited directly on the Si substrate. The subsequent N2 annealing at high temperature (>= 700 °C) not only results in the polycrystallization of the multilayered high-k films, but also causes the diffusion of Zr. The latter transforms the HfSixOy/HfO2/IL/ZrO2/IL/HfO2 film into the Zr-doped HfO2 film, and improves electrical properties in general. However, the thin SiOx interfacial layer starts to form if annealing temperature increases over 700 °C, deteriorating the equivalent oxide thickness. .

Surface instability of an imperfectly bonded thin elastic film under surface van der Waals forces

NASA Astrophysics Data System (ADS)

Wang, Xu; Jing, Rong

2017-02-01

This paper studies surface instability of a thin elastic film imperfectly bonded to a rigid substrate interacting with a rigid contactor through van der Waals forces under plane strain conditions. The film-substrate interface is modeled as a linear spring with vanishing thickness described in terms of the normal and tangential interface parameters. Depending on the ratio of the two imperfect interface parameters, the critical value of the Poisson's ratio for the occurrence of surface wrinkling in the absence of surface energy can be greater than, equal to, or smaller than 0.25, which is the critical Poisson's ratio for a perfect film-substrate interface. The critical surface energy for the inhibition of the surface wrinkling is also obtained. Finally, we propose a very simple and effective method to study the surface instability of a multilayered elastic film with imperfect interfaces interacting with a rigid contactor or with another multilayered elastic film (or a multilayered simply supported plate) with imperfect interfaces.

Casting Of Multilayer Ceramic Tapes

NASA Technical Reports Server (NTRS)

Collins, Earl R., Jr.

1991-01-01

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.

Novel sol-gel precursors for thin mesoporous eu(3+)-doped silica coatings as efficient luminescent materials.

PubMed

Feinle, Andrea; Lavoie-Cardinal, Flavie; Akbarzadeh, Johanna; Peterlik, Herwig; Adlung, Matthias; Wickleder, Claudia; Hüsing, Nicola

2012-10-09

Europium(III) ions containing mesoporous silica coatings have been prepared via a solvent evaporation-induced self-assembly (EISA) approach of different single-source precursors (SSPs) in the presence of Pluronic P123 as a structure-directing agent, using the spin-coating process. A deliberate tailoring of the chemical composition of the porous coatings with various Si:Eu ratios was achieved by processing mixtures of tetraethylorthosilicate (TEOS) and Eu(3+)-coordinated SSPs. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) analyses demonstrate that the thin metal oxide-doped silica coatings consist of a porous network with a short-range order of the pore structure, even at high europium(III) loadings. Furthermore, luminescence properties were investigated at different temperatures and different degrees of Eu(3+) contents. The photoluminescence spectra clearly show characteristic emission peaks corresponding to the (5)D0 → (7)FJ (J = 0-5) transitions resulting in a red luminescence visible by the eyes, although the films have a very low thickness (150-200 nm).

A zinc phthalocyanine based periodic mesoporous organosilica exhibiting charge transfer to fullerenes.

PubMed

Auras, Florian; Li, Yan; Löbermann, Florian; Döblinger, Markus; Schuster, Jörg; Peter, Laurence M; Trauner, Dirk; Bein, Thomas

2014-11-10

Periodic mesoporous organosilica (PMO) materials offer a strategy to position molecular semiconductors within a highly defined, porous network. We developed thin films of a new semiconducting zinc phthalocyanine-bridged PMO exhibiting a face-centered orthorhombic pore structure with an average pore diameter of 11 nm. The exceptional degree of order achieved with this PMO enabled us to create thin films consisting of a single porous domain throughout their entire thickness, thus providing maximal accessibility for subsequent incorporation of a complementary phase. The phthalocyanine building blocks inside the pore walls were found to be well-aggregated, enabling electronic conductivity and extending the light-harvesting capabilities to the near IR region. Ordered 3D heterojunctions capable of promoting photo-induced charge transfer were constructed by impregnation of the PMO with a fullerene derivative. When integrated into a photovoltaic device, the infiltrated PMO is capable of producing a high open-circuit voltage and a considerable photocurrent, which represents a significant step towards potential applications of PMOs in optoelectronics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Critical aspects in the production of periodically ordered mesoporous titania thin films.

PubMed

Soler-Illia, Galo J A A; Angelomé, Paula C; Fuertes, M Cecilia; Grosso, David; Boissiere, Cedric

2012-04-21

Periodically ordered mesoporous titania thin films (MTTF) present a high surface area, controlled porosity in the 2-20 nm pore diameter range and an amorphous or crystalline inorganic framework. These materials are nowadays routinely prepared by combining soft chemistry and supramolecular templating. Photocatalytic transparent coatings and titania-based solar cells are the immediate promising applications. However, a wealth of new prospective uses have emerged on the horizon, such as advanced catalysts, perm-selective membranes, optical materials based on plasmonics and photonics, metamaterials, biomaterials or new magnetic nanocomposites. Current and novel applications rely on the ultimate control of the materials features such as pore size and geometry, surface functionality and wall structure. Even if a certain control of these characteristics has been provided by the methods reported so far, the needs for the next generation of MTTF require a deeper insight in the physical and chemical processes taking place in their preparation and processing. This article presents a critical discussion of these aspects. This discussion is essential to evolve from know-how to sound knowledge, aiming at a rational materials design of these fascinating systems.

Synergistic effects of graphene quantum dot sensitization and nitrogen doping of ordered mesoporous TiO2 thin films for water splitting photocatalysis(Conference Presentation)

NASA Astrophysics Data System (ADS)

Islam, Syed Z.; Wanninayake, Namal; Reed, Allen D.; Kim, Doo-Young; Rankin, Stephen E.

2016-10-01

The optical and electronic properties of TiO2 thin films provide tremendous opportunities in several applications including photocatalysis, photovoltaics and photoconductors for energy production. Despite many attractive features of TiO2, critical challenges include the innate inability of TiO2 to absorb visible light and the fast recombination of photoexcited charge carriers. In this study, we prepared ordered mesoporous TiO2 films co-modified by graphene quantum dot sensitization and nitrogen doping (GQD-N-TiO2) for hydrogen production from photoelectrochemical water splitting under visible light irradiation. First, cubic ordered mesoporous TiO2 films were prepared by a surfactant templated sol-gel method. Then, TiO2 films were treated with N2/Ar plasma for the incorporation of substitutional N atoms into the lattice of TiO2. GQDs were prepared by chemically oxidizing carbon nano-onions. The immobilization of GQDs was accomplished by reacting carboxyl groups of GQDs with amine groups of N-TiO2 developed by the prior immobilization of (3-aminopropyl)triethoxysilane (APTES). Successful immobilization of GQDs onto N-TiO2 was probed by UV-Vis, FT-IR, and scanning electron microscopy. Further, zeta potential and contact angle measurements showed enhanced surface charge and hydrophilicity, confirming the successful immobilization of GQDs. The GQD-N-TiO2, N-TiO2 and GQD-TiO2 films showed 400 times, 130 times and 8 times photocurrent enhancement, respectively, compared to TiO2 films for water splitting with a halogen bulb light source. This outstanding enhancement is attributed to the high surface area of mesoporous films and synergistic effects of nitrogen doping and GQD sensitization resulting in enhanced visible light absorption, efficient charge separation and transport.

Carbonate pore system evaluation using the velocity-porosity-pressure relationship, digital image analysis, and differential effective medium theory

NASA Astrophysics Data System (ADS)

Lima Neto, Irineu A.; Misságia, Roseane M.; Ceia, Marco A.; Archilha, Nathaly L.; Oliveira, Lucas C.

2014-11-01

Carbonate reservoirs exhibit heterogeneous pore systems and a wide variety of grain types, which affect the rock's elastic properties and the reservoir parameter relationships. To study the Albian carbonates in the Campos Basin, a methodology is proposed to predict the amount of microporosity and the representative aspect ratio of these inclusions. The method assumes three pore-space scales in two representative inclusion scenarios: 1) a macro-mesopore median aspect ratio from the thin-section digital image analysis (DIA) and 2) a microporosity aspect ratio predicted based on the measured P-wave velocities. Through a laboratory analysis of 10 grainstone core samples of the Albian age, the P- and S-wave velocities (Vp and Vs) are evaluated at effective pressures of 0-10 MPa. The analytical theories in the proposed methodology are functions of the aspect ratios from the differential effective medium (DEM) theory, the macro-mesopore system recognized from the DIA, the amount of microporosity determined by the difference between the porosities estimated from laboratorial helium-gas and the thin-section petrographic images, and the P-wave velocities under dry effective pressure conditions. The DIA procedure is applied to estimate the local and global parameters, and the textural implications concerning ultrasonic velocities and image resolution. The macro-mesopore inclusions contribute to stiffer rocks and higher velocities, whereas the microporosity inclusions contribute to softer rocks and lower velocities. We observe a high potential for this methodology, which uses the microporosity aspect ratio inverted from Vp to predict Vs with a good agreement. The results acceptably characterize the Albian grainstones. The representative macro-mesopore aspect ratio is 0.5, and the inverted microporosity aspect ratio ranges from 0.01 to 0.07. The effective pressure induced an effect of slight porosity reduction during the triaxial tests, mainly in the microporosity inclusions, slightly changing the amount and the aspect ratio of the microporosity.

Method for Fabricating Miniaturized NiTi Self-Expandable Thin Film Devices with Increased Radiopacity

NASA Astrophysics Data System (ADS)

Bechtold, Christoph; Lima de Miranda, Rodrigo; Chluba, Christoph; Zamponi, Christiane; Quandt, Eckhard

2016-12-01

Nitinol is the material of choice for many medical applications, in particular for minimally invasive implants due to its superelasticity and biocompatibility. However, NiTi has limited radiopacity which complicates positioning in the body. A common strategy to increase the radiopacity of NiTi devices is the addition of radiopaque markers by micro-riveting or micro-welding. The recent trend of miniaturizing medical devices, however, reduces their radiopacity further, and makes the addition of radiopaque markers to these miniaturized devices difficult. NiTi thin film technology has great potential to overcome such limitations and to fabricate new generations of miniaturized, self-expandable NiTi medical devices with additional functionalities, such as structured multilayer devices with increased radiopacity. For this purpose, we have produced superelastic thin film NiTi samples covered locally with Tantalum structures of different thickness and different shape. These multilayer devices were characterized regarding their mechanical and corrosion properties as well as their X-ray visibility. The superelastic behavior of the underlying NiTi layer is impeded by the Ta layer, and shows therefore a dependence on the Tantalum patterning geometry and thickness. No delamination was observed after mechanical and corrosion tests. The multilayers reveal excellent corrosion resistance, as well as a significant increase in radiopacity.

Study on Ultrafast Photodynamics of Novel Multilayered Thin Films for Device Applications

DTIC Science & Technology

2004-07-31

study ultrafast phase-transition of VO2 thin film. This part of work was started right after the new laser installed. With better laser output...1-3]. With the purpose of combined effect that the proposed ultrafast phase-transition VO2 thin film deposited on a substrate of heavy metal...second point of focus was to study ultrafast phase-transition of VO2 thin film. This part of work was started right after the new laser installed

Metamaterial Perfect Absorber Analyzed by a Meta-Cavity Model Consisting of Multilayer Metasurfaces (Postprint)

DTIC Science & Technology

2017-09-05

metamaterial perfect absorber behaves as a meta-cavity bounded between a resonant metasurface and a metallic thin- film reflector. The perfect absorption...cavity quantum electrodynamics devices. 15. SUBJECT TERMS Metamaterial; meta-cavity; metallic thin- film reflector; Fabry-Perot cavity resonance...metamaterial perfect absorber behaves as a meta-cavity bounded between a resonant metasurface and a metallic thin- film reflector. The perfect absorption is

Melting Behavior of Al/Pb/Sn/Al Multilayered Thin Films

NASA Astrophysics Data System (ADS)

Khan, Patan Yousaf; Devi, M. Manolata; Biswas, Krishanu

2015-09-01

Metals or alloy nanoparticles (NPs) have been reported to exhibit superheating on melting when coated with higher melting point material or embedded in a matrix. This is due to the suppression of the heterogeneous nucleation of the melt at the epitaxial interface. For 2D thin films, this necessary condition is not feasible because even if a thin film is sandwiched between higher melting temperature materials with coherent interfaces, the heterogeneous nucleation of melt is possible at various detects. However, it has earlier been reported that 2D thin films of the pure metal sandwiched by other materials can exhibit superheating by suppression of melt growth. In order to probe this effect in case of alloy thin films, the present investigation has been carried out on Pb/Sn multilayers sandwiched between Al layers. The present study shows that such sandwiched thin films prepared by accumulative roll bonding process cause the formation of biphasic NPs in the intermixed region of Pb and Sn. Al layers undergo severe plastic deformation, leading to the generation of dislocations and sub-grain boundaries. DSC (differential canning calorimeter) thermograms of the films indicate superheating of 3 K to 6 K (or 3 °C to 6 °C). Theoretical analysis using currently available literatures has been carried out to justify the finding in the present investigation.

Facile synthesis of functionalized ionic surfactant templated mesoporous silica for incorporation of poorly water-soluble drug.

PubMed

Li, Jing; Xu, Lu; Yang, Baixue; Wang, Hongyu; Bao, Zhihong; Pan, Weisan; Li, Sanming

2015-08-15

The present paper reported amino group functionalized anionic surfactant templated mesoporous silica (Amino-AMS) for loading and release of poorly water-soluble drug indomethacin (IMC) and carboxyl group functionalized cationic surfactant templated mesoporous silica (Carboxyl-CMS) for loading and release of poorly water-soluble drug famotidine (FMT). Herein, Amino-AMS and Carboxyl-CMS were facilely synthesized using co-condensation method through two types of silane coupling agent. Amino-AMS was spherical nanoparticles, and Carboxyl-CMS was well-formed spherical nanosphere with a thin layer presented at the edge. Drug loading capacity was obviously enhanced when using Amino-AMS and Carboxyl-CMS as drug carriers due to the stronger hydrogen bonding force formed between surface modified carrier and drug. Amino-AMS and Carboxyl-CMS had the ability to transform crystalline state of loaded drug from crystalline phase to amorphous phase. Therefore, IMC loaded Amino-AMS presented obviously faster release than IMC because amorphous phase of IMC favored its dissolution. The application of asymmetric membrane capsule delayed FMT release significantly, and Carboxyl-CMS favored sustained release of FMT due to its long mesoporous channels and strong interaction formed between its carboxyl group and amino group of FMT. Copyright © 2015 Elsevier B.V. All rights reserved.

High spin-polarization in ultrathin Co2MnSi/CoPd multilayers

NASA Astrophysics Data System (ADS)

Galanakis, I.

2015-03-01

Half-metallic Co2MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co2MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co2MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices.

Surface analysis monitoring of polyelectrolyte deposition on Ba 0.5Sr 0.5TiO 3 thin films

NASA Astrophysics Data System (ADS)

Morales-Cruz, Angel L.; Fachini, Estevão R.; Miranda, Félix A.; Cabrera, Carlos R.

2007-09-01

Thin films are currently gaining interest in many areas such as integrated optics, sensors, friction, reducing coatings, surface orientation layers, and general industrial applications. Recently, molecular self-assembling techniques have been applied for thin film deposition of electrically conducting polymers, conjugated polymers for light-emitting devices, nanoparticles, and noncentrosymmetric-ordered second order nonlinear optical (NOL) devices. Polyelectrolytes self-assemblies have been used to prepare thin films. The alternate immersion of a charged surface in polyannion and a polycation solution leads usually to the formation of films known as polyelectrolyte multilayers. These polyanion and polycation structures are not neutral. However, charge compensation appears on the surface. This constitutes the building driving force of the polyelectrolyte multilayer films. The present approach consists of two parts: (a) the chemisorption of 11-mercaptoundecylamine (MUA) to construct a self-assembled monolayer with the consequent protonation of the amine, and (b) the deposition of opposite charged polyelectrolytes in a sandwich fashion. The approach has the advantage that ionic attraction between opposite charges is the driving force for the multilayer buildup. For our purposes, the multilayer of polyelectrolytes depends on the quality of the surface needed for the application. In many cases, this approach will be used in a way that the roughness factor defects will be diminished. The polyelectrolytes selected for the study were: polystyrene sulfonate sodium salt (PSS), poly vinylsulfate potassium salt (PVS), and polyallylamine hydrochloride (PAH), as shown in Fig. 1. The deposition of polyelectrolytes was carried out by a dipping procedure with the corresponding polyelectrolyte. Monitoring of the alternate deposition of polyelectrolyte bilayers was done by surface analysis techniques such as X-ray photoelectron spectroscopy (XPS), specular reflectance infrared (IR), and atomic force microscopy (AFM). The surface analysis results are presented through the adsorption steps of the polyelectrolytes layer by layer.

Artificial multilayers and nanomagnetic materials

PubMed Central

SHINJO, Teruya

2013-01-01

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. PMID:23391605

X-ray/EUV optics for astronomy, microscopy, polarimetry, and projection lithography; Proceedings of the Meeting, San Diego, CA, July 9-13, 1990

NASA Technical Reports Server (NTRS)

Hoover, Richard B. (Editor); Walker, Arthur B. C., Jr. (Editor)

1991-01-01

Topics discussed in this issue include the fabrication of multilayer X-ray/EUV coatings; the design, characterization, and test of multilayer X-ray/EUV coatings; multilayer X-ray/EUV monochromators and imaging microscopes; X-ray/EUV telescopes; the test and calibration performance of X-ray/EUV instruments; XUV/soft X-ray projection lithography; X-ray/EUV space observatories and missions; X-ray/EUV telescopes for solar research; X-ray/EUV polarimetry; X-ray/EUV spectrographs; and X-ray/EUV filters and gratings. Papers are presented on the deposition-controlled uniformity of multilayer mirrors, interfaces in Mo/Si multilayers, the design and analysis of an aspherical multilayer imaging X-ray microscope, recent developments in the production of thin X-ray reflecting foils, and the ultraprecise scanning technology. Consideration is also given to an active sun telescope array, the fabrication and performance at 1.33 nm of a 0.24-micron-period multilayer grating, a cylindrical proportional counter for X-ray polarimetry, and the design and analysis of the reflection grating arrays for the X-Ray Multi-Mirror Mission.

Triblock copolymer micelles as templates for preparation of mesoporous niobia thin films

NASA Astrophysics Data System (ADS)

Georgiev, R.; Christova, D.; Todorova, L.; Georgieva, B.; Vasileva, M.; Novakov, Ch; Babeva, T.

2018-03-01

The micelle formation of commercially available Pluronic PE 6800 (PEO-PPO-PEO triblock copolymer) was studied by means of a dye solubilization method, and the solubility of 1,6-diphenyl-1,3,5-hexatriene in aqueous solutions of the copolymer with concentrations ranging from 0.05 to 20 % w/v was studied by recording the transmission and emission spectra of the solutions using UV-VIS and photoluminescence spectroscopy, respectively. Further, mesoporous Nb2O5 films using PE 6800 micelles templates were obtained through sol-gel using spin-coating; their morphology, structure and optical properties were studied by TEM, SAED and nonlinear fitting of reflectance measurements. The possible application of the films in optical sensing of vapors was demonstrated and discussed.

A process for preparing an ultra-thin, adhesiveless, multi-layered, patterned polymer substrate

NASA Technical Reports Server (NTRS)

Bryant, Robert G. (Inventor); Kruse, Nancy H. M. (Inventor); Fox, Robert L. (Inventor); Tran, Sang Q. (Inventor)

1995-01-01

A process for preparing an ultra-thin, adhesiveless, multi-layered, patterned polymer substrate is disclosed. The process may be used to prepare both rigid and flexible cables and circuit boards. A substrate is provided and a polymeric solution comprising a self-bonding, soluble polymer and a solvent is applied to the substrate. Next, the polymer solution is dried to form a polymer coated substrate. The polymer coated substrate is metallized and patterned. At least one additional coating of the polymeric solution is applied to the metallized, patterned, polymer coated substrate and the steps of metallizing and patterning are repeated. Lastly, a cover coat is applied. When preparing a flexible cable and flexible circuit board, the polymer coating is removed from the substrate.

Improvement of laser molecular beam epitaxy grown SrTiO3 thin film properties by temperature gradient modulation growth

NASA Astrophysics Data System (ADS)

Li, Jin Long; Hao, J. H.; Li, Y. R.

2007-09-01

Oxygen diffusion at the SrTiO3/Si interface was analyzed. A method called temperature gradient modulation growth was introduced to control oxygen diffusion at the interface of SrTiO3/Si. Nanoscale multilayers were grown at different temperatures at the initial growing stage of films. Continuous growth of SrTiO3 films was followed to deposit on the grown sacrificial layers. The interface and crystallinity of SrTiO3/Si were investigated by in situ reflection high energy electron diffraction and x-ray diffraction measurements. It has been shown that the modulated multilayers may help suppress the interfacial diffusion, and therefore improve SrTiO3 thin film properties.

Dye-sensitized electron transfer from TiO 2 to oxidized triphenylamines that follows first-order kinetics

DOE PAGES

DiMarco, Brian N.; Troian-Gautier, Ludovic; Sampaio, Renato N.; ...

2018-01-01

Two sensitizers, [Ru(bpy) 2 (dcb)] 2+ ( RuC ) and [Ru(bpy) 2 (dpb)] 2+ ( RuP ), were anchored to mesoporous TiO 2 thin films and utilized to sensitize the reaction of TiO 2 electrons with oxidized triphenylamines to visible light in CH 3 CN electrolytes.

Protein-Containing Lipid Bilayers Intercalated with Size-Matched Mesoporous Silica Thin Films

DOE PAGES

Isaksson, Simon; Watkins, Erik Benjamin; Browning, Kathryn L.; ...

2016-11-23

Here, proteins are key components in a multitude of biological processes, of which the functions carried out by transmembrane (membrane-spanning) proteins are especially demanding for investigations. This is because this class of protein needs to be incorporated into a lipid bilayer representing its native environment, and in addition, many experimental conditions also require a solid support for stabilization and analytical purposes. The solid support substrate may, however, limit the protein functionality due to protein–material interactions and a lack of physical space. We have in this work tailored the pore size and pore ordering of a mesoporous silica thin film tomore » match the native cell-membrane arrangement of the transmembrane protein human aquaporin 4 (hAQP4). Using neutron reflectivity (NR), we provide evidence of how substrate pores host the bulky water-soluble domain of hAQP4, which is shown to extend 7.2 nm into the pores of the substrate. Complementary surface analytical tools, including quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescence microscopy, revealed successful protein-containing supported lipid bilayer (pSLB) formation on mesoporous silica substrates, whereas pSLB formation was hampered on nonporous silica. Additionally, electron microscopy (TEM and SEM), light scattering (DLS and stopped-flow), and small-angle X-ray scattering (SAXS) were employed to provide a comprehensive characterization of this novel hybrid organic–inorganic interface, the tailoring of which is likely to be generally applicable to improve the function and stability of a broad range of membrane proteins containing water-soluble domains.« less

Quantum dots/silica/polymer nanocomposite films with high visible light transmission and UV shielding properties

NASA Astrophysics Data System (ADS)

Mumin, Md Abdul; Xu, William Z.; Charpentier, Paul A.

2015-08-01

The dispersion of light-absorbing inorganic nanomaterials in transparent plastics such as poly(ethylene-co-vinyl acetate) (PEVA) is of enormous current interest in emerging solar materials, including photovoltaic (PV) modules and commercial greenhouse films. Nanocrystalline semiconductor or quantum dots (QDs) have the potential to absorb UV light and selectively emit visible light, which can control plant growth in greenhouses or enhance PV panel efficiencies. This work provides a new and simple approach for loading mesoporous silica-encapsulated QDs into PEVA. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm size were synthesized using a modified facile approach based on pyrolysis of the single-molecule precursors and capping the CdS QDs with a thin layer of ZnS. To make both the bare and core-shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interactions. By careful experimental tuning, this encapsulation technique enhanced the quantum yield (˜65%) and photostability compared to the bare QDs. Both the encapsulated bare and core-shell QDs were then melt-mixed with EVA pellets using a mini twin-screw extruder and pressed into thin films with controlled thickness. The results demonstrated for the first time that mesoporous silica not only enhanced the quantum yield and photostability of the QDs but also improved the compatibility and dispersibility of QDs throughout the PEVA films. The novel light selective films show high visible light transmission (˜90%) and decreased UV transmission (˜75%).

Quantum dots/silica/polymer nanocomposite films with high visible light transmission and UV shielding properties.

PubMed

Mumin, Md Abdul; Xu, William Z; Charpentier, Paul A

2015-08-07

The dispersion of light-absorbing inorganic nanomaterials in transparent plastics such as poly(ethylene-co-vinyl acetate) (PEVA) is of enormous current interest in emerging solar materials, including photovoltaic (PV) modules and commercial greenhouse films. Nanocrystalline semiconductor or quantum dots (QDs) have the potential to absorb UV light and selectively emit visible light, which can control plant growth in greenhouses or enhance PV panel efficiencies. This work provides a new and simple approach for loading mesoporous silica-encapsulated QDs into PEVA. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm size were synthesized using a modified facile approach based on pyrolysis of the single-molecule precursors and capping the CdS QDs with a thin layer of ZnS. To make both the bare and core-shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interactions. By careful experimental tuning, this encapsulation technique enhanced the quantum yield (∼65%) and photostability compared to the bare QDs. Both the encapsulated bare and core-shell QDs were then melt-mixed with EVA pellets using a mini twin-screw extruder and pressed into thin films with controlled thickness. The results demonstrated for the first time that mesoporous silica not only enhanced the quantum yield and photostability of the QDs but also improved the compatibility and dispersibility of QDs throughout the PEVA films. The novel light selective films show high visible light transmission (∼90%) and decreased UV transmission (∼75%).

Protein-Containing Lipid Bilayers Intercalated with Size-Matched Mesoporous Silica Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isaksson, Simon; Watkins, Erik Benjamin; Browning, Kathryn L.

Here, proteins are key components in a multitude of biological processes, of which the functions carried out by transmembrane (membrane-spanning) proteins are especially demanding for investigations. This is because this class of protein needs to be incorporated into a lipid bilayer representing its native environment, and in addition, many experimental conditions also require a solid support for stabilization and analytical purposes. The solid support substrate may, however, limit the protein functionality due to protein–material interactions and a lack of physical space. We have in this work tailored the pore size and pore ordering of a mesoporous silica thin film tomore » match the native cell-membrane arrangement of the transmembrane protein human aquaporin 4 (hAQP4). Using neutron reflectivity (NR), we provide evidence of how substrate pores host the bulky water-soluble domain of hAQP4, which is shown to extend 7.2 nm into the pores of the substrate. Complementary surface analytical tools, including quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescence microscopy, revealed successful protein-containing supported lipid bilayer (pSLB) formation on mesoporous silica substrates, whereas pSLB formation was hampered on nonporous silica. Additionally, electron microscopy (TEM and SEM), light scattering (DLS and stopped-flow), and small-angle X-ray scattering (SAXS) were employed to provide a comprehensive characterization of this novel hybrid organic–inorganic interface, the tailoring of which is likely to be generally applicable to improve the function and stability of a broad range of membrane proteins containing water-soluble domains.« less

NbTiN Based SIS Multilayer Structures for SRF Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valente, Anne-marie; Eremeev, Grigory; Phillips, H

2013-09-01

For the past three decades, bulk niobium has been the material of choice for SRF cavities applications. RF cavity performance is now approaching the theoretical limit for bulk niobium. For further improvement of RF cavity performance for future accelerator projects, Superconductor Insulator - Superconductor (SIS) multilayer structures (as recently proposed by Alex Gurevich) present the theoretical prospect to reach RF performance beyond bulk Nb, using thinly layered higher-Tc superconductors with enhanced Hc1. Jefferson Lab (JLab) is pursuing this approach with the development of NbTiN and AlN based multilayer SIS structures. This paper presents the results on the characteristics of NbTiNmore » films and the first RF measurements on NbTiN-based multilayer structure on thick Nb films.« less

Method of manufacture of atomically thin boron nitride

DOEpatents

Zettl, Alexander K

2013-08-06

The present invention provides a method of fabricating at least one single layer hexagonal boron nitride (h-BN). In an exemplary embodiment, the method includes (1) suspending at least one multilayer boron nitride across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure. The present invention also provides a method of fabricating single layer hexagonal boron nitride. In an exemplary embodiment, the method includes (1) providing multilayer boron nitride suspended across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hannachi, Amira, E-mail: amira.hannachi88@gmail.com; Maghraoui-Meherzi, Hager

Manganese sulfide thin films have been deposited on glass slides by chemical bath deposition (CBD) method. The effects of preparative parameters such as deposition time, bath temperature, concentration of precursors, multi-layer deposition, different source of manganese, different complexing agent and thermal annealing on structural and morphological film properties have been investigated. The prepared thin films have been characterized using the X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). It exhibit the metastable forms of MnS, the hexagonal γ-MnS wurtzite phase with preferential orientation in the (002) plane or the cubic β-MnS zinc blende with preferentialmore » orientation in the (200) plane. Microstructural studies revealed the formation of MnS crystals with different morphologies, such as hexagons, spheres, cubes or flowers like. - Graphical Abstract: We report the preparation of different phases of manganese sulfide thin films (γ, β and α-MnS) by chemical bath deposition method. The effects of deposition parameters such as deposition time and temperature, concentrations of precursors and multi-layer deposition on MnS thin films structure and morphology were investigated. The influence of thermal annealing under nitrogen atmosphere at different temperature on MnS properties was also studied. Different manganese precursors as well as different complexing agent were also used. - Highlights: • γ and β-MnS films were deposited on substrate using the chemical bath deposition. • The effect of deposition parameters on MnS film properties has been investigated. • Multi-layer deposition was also studied to increase film thickness. • The effect of annealing under N{sub 2} at different temperature was investigated.« less

Deformable Hollow Periodic Mesoporous Organosilica Nanocapsules for Significantly Improved Cellular Uptake.

PubMed

Teng, Zhaogang; Wang, Chunyan; Tang, Yuxia; Li, Wei; Bao, Lei; Zhang, Xuehua; Su, Xiaodan; Zhang, Fan; Zhang, Junjie; Wang, Shouju; Zhao, Dongyuan; Lu, Guangming

2018-01-31

Mesoporous solids have been widely used in various biomedical areas such as drug delivery and tumor therapy. Although deformability has been recognized as a prime important characteristic influencing cellular uptake, the synthesis of deformable mesoporous solids is still a great challenge. Herein, deformable thioether-, benzene-, and ethane-bridged hollow periodic mesoporous organosilica (HPMO) nanocapsules have successfully been synthesized for the first time by a preferential etching approach. The prepared HPMO nanocapsules possess uniform diameters (240-310 nm), high surface areas (up to 878 m 2 ·g -1 ), well-defined mesopores (2.6-3.2 nm), and large pore volumes (0.33-0.75 m 3 ·g -1 ). Most importantly, the HPMO nanocapsules simultaneously have large hollow cavities (164-270 nm), thin shell thicknesses (20-38 nm), and abundant organic moiety in the shells, which endow a lower Young's modulus (E Y ) of 3.95 MPa than that of solid PMO nanoparticles (251 MPa). The HPMOs with low E Y are intrinsically flexible and deformable in the solution, which has been well-characterized by liquid cell electron microscopy. More interestingly, it is found that the deformable HPMOs can easily enter into human breast cancer MCF-7 cells via a spherical-to-oval morphology change, resulting in a 26-fold enhancement in cellular uptake (43.1% cells internalized with nanocapsules versus 1.65% cells with solid counterparts). The deformable HPMO nanocapsules were further loaded with anticancer drug doxorubicin (DOX), which shows high killing effects for MCF-7 cells, demonstrating the promise for biomedical applications.

MOVPE of GaSb/InGaAsSb Multilayers and Fabrication of Dual Band Photodetectors

NASA Technical Reports Server (NTRS)

Xiao, Ye-Gao; Bhat, Ishwara; Refaat, Tamer F.; Abedin, M. Nurul; Shao, Qing-Hui

2005-01-01

Metalorganic vapor phase epitaxy (MOVPE) of GaSb/InGaAsSb multilayer thin films and fabrication of bias-selectable dual band photodetectors are reported. For the dual band photodetectors the short wavelength detector, or the upper p- GaSb/n-GaSb junction photodiode, is placed optically ahead of the long wavelength one, or the lower photodiode. The latter is based on latticed-matched In0.13Ga0.87As0.11Sb0.89 with bandgap near 0.6 eV. Specifically, high quality multilayer thin films are grown sequentially from top to bottom as p+-GaSb/p-GaSb/n-GaSb/n-InGaAsSb/p-InGaAsSb/p-GaSb on undoped p-type GaSb substrate, and as n-GaSb/p-GaSb/p-InGaAsSb/n-InGaAsSb/n-GaSb on Te-doped n-type GaSb substrate respectively. The multilayer thin films are characterized by optical microscope, atomic force microscope (AFM), electron microprobe analyses etc. The photodiode mesa steps are patterned by photolithography with wet chemical etching and the front metallization is carried out by e-beam evaporation with Pd/Ge/Au/Ti/Au to give ohmic contact on both n- and p-type Sb based layer surfaces. Dark I-V measurements show typical diode behavior for both the upper and lower photodiodes. The photoresponsivity measurements indicate that both the upper and lower photodiodes can sense the infrared illumination corresponding to their cutoff wavelengths respectively, comparable with the simulation results. More work is underway to bring the long wavelength band to the medium infrared wavelength region near 4 micrometers.

Enhanced energy harvesting by concentration gradient-driven ion transport in SBA-15 mesoporous silica thin films.

PubMed

Hwang, Junho; Kataoka, Sho; Endo, Akira; Daiguji, Hirofumi

2016-09-21

Nanofluidic energy harvesting systems have attracted interest in the field of battery application, particularly for miniaturized electrical devices, because they possess excellent energy conversion capability for their size. In this study, a mesoporous silica (MPS)-based nanofluidic energy harvesting system was fabricated and selective ion transport in mesopores as a function of the salt gradient was investigated. Aqueous solutions with three different kinds of monovalent electrolytes-KCl, NaCl, and LiCl-with different diffusion coefficients (D + ) were considered. The highest power density was 3.90 W m -2 for KCl, followed by 2.39 W m -2 for NaCl and 1.29 W m -2 for LiCl. Furthermore, the dependency of power density on the type of cation employed indicates that the harvested energy increases as the cation mobility increases, particularly at high concentrations. This cation-specific dependency suggests that the maximum power density increases by increasing the diffusion coefficient ratio of cations to anions, making this ratio a critical parameter in enhancing the performance of nanofluidic energy harvesting systems with extremely small pores ranging from 2 to 3 nm.

A Hierarchical MFI Zeolite with a Two-Dimensional Square Mesostructure.

PubMed

Shen, Xuefeng; Mao, Wenting; Ma, Yanhang; Xu, Dongdong; Wu, Peng; Terasaki, Osamu; Han, Lu; Che, Shunai

2018-01-15

A conceptual design and synthesis of ordered mesoporous zeolites is a challenging research subject in material science. Several seminal articles report that one-dimensional (1D) mesostructured lamellar zeolites are possibly directed by sheet-assembly of surfactants, which collapse after removal of intercalated surfactants. However, except for one example of two-dimensional (2D) hexagonal mesoporous zeolite, no other zeolites with ordered 2D or three-dimensional (3D) mesostructures have been reported. An ordered 2D mesoporous zeolite can be templated by a cylindrical assembly unit with specific interactions in the hydrophobic part. A template molecule with azobenzene in the hydrophobic tail and diquaternary ammonium in the hydrophilic head group directs hierarchical MFI zeolite with a 2D square mesostructure. The material has an elongated octahedral morphology, and quaternary, ordered, straight, square channels framed by MFI thin sheets expanded along the a-c planes and joined with 90° rotations. The structural matching between the cylindrical assembly unit and zeolite framework is crucial for mesostructure construction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ordered Mesoporous Titania/Carbon Hybrid Monoliths for Lithium-ion Battery Anodes with High Areal and Volumetric Capacity.

PubMed

Dörr, Tobias S; Fleischmann, Simon; Zeiger, Marco; Grobelsek, Ingrid; de Oliveira, Peter W; Presser, Volker

2018-04-25

Free-standing, binder-free, and conductive additive-free mesoporous titanium dioxide/carbon hybrid electrodes were prepared from co-assembly of a poly(isoprene)-block-poly(styrene)-block-poly(ethylene oxide) block copolymer and a titanium alkoxide. By tailoring an optimized morphology, we prepared macroscopic mechanically stable 300 μm thick monoliths that were directly employed as lithium-ion battery electrodes. High areal mass loading of up to 26.4 mg cm -2 and a high bulk density of 0.88 g cm -3 were obtained. This resulted in a highly increased volumetric capacity of 155 mAh cm -3 , compared to cast thin film electrodes. Further, the areal capacity of 4.5 mAh cm -2 represented a 9-fold increase compared to conventionally cast electrodes. These attractive performance metrics are related to the superior electrolyte transport and shortened diffusion lengths provided by the interconnected mesoporous nature of the monolith material, assuring superior rate handling, even at high cycling rates. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel concept for the preparation of gas selective nanocomposite membranes

NASA Astrophysics Data System (ADS)

Drobek, M.; Ayral, A.; Motuzas, J.; Charmette, C.; Loubat, C.; Louradour, E.; Dhaler, D.; Julbe, A.

2015-07-01

In this work we report on a novel concept for the preparation of gas selective composite membranes by a simple and robust synthesis protocol involving a controlled in-situpolycondensation of functional alkoxysilanes within the pores of a mesoporous ceramic matrix. This innovative approach targets the manufacture of thin nanocomposite membranes, allowing good compromise between permeability, selectivity and thermomechanical strength. Compared to simple infiltration, the synthesis protocol allows a controlled formation of gas separation membranes from size-adjusted functional alkoxysilanes by a chemical reaction within the mesopores of a ceramic support, without any formation of a thick and continuous layer on the support top-surface. Membrane permeability can thus be effectively controlled by the thickness and pore size of the mesoporous layer, and by the oligomers chain length. The as-prepared composite membranes are expected to possess a good mechanical and thermomechanical resistance and exhibit a thermally activated transport of He and H2 up to 150 °C, resulting in enhanced separation factors for specific gas mixtures e.g. FH2/CO ˜ 10; FH2/CO2 ˜ 3; FH2/CH4 ˜ 62.

Characterization of TiN/B-C-N multilayers by transmission electron microscopy, ion beam backscattering, and low angle x-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kung, H.; Fayeulle, S.; Nastasi, M.

1997-10-01

The effects of Ar ion irradiation on the structure and stability of multilayered DC sputtered thin films of TiN/B-C-N have been studied. An increase of the bilayer repeat length to a maximum of 12.8% and departure of nitrogen from the film was observed indicating the interdiffusion between TiN and B-C-N layers. For the highest dose (5 {times} 10{sup 16} ions/cm{sup 2}) the multilayered structure partly disappears. The various mechanisms are discussed in terms of stress-driven diffusion and viscous flow of atoms.

Stabilization of solar films against hi temperature deactivation

DOEpatents

Jefferson, Clinton F.

1984-03-20

A multi-layer solar energy collector of improved stability comprising: (1) a solar absorptive film consisting essentially of copper oxide, cobalt oxide and manganese oxide; (2) a substrate of quartz, silicate glass or a stainless steel; and (3) an interlayer of platinum, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of platinum to obtain a stable conductor-dielectric tandem.

Combinatorial investigation of Fe–B thin-film nanocomposites

PubMed Central

Brunken, Hayo; Grochla, Dario; Savan, Alan; Kieschnick, Michael; Meijer, Jan D; Ludwig, Alfred

2011-01-01

Combinatorial magnetron sputter deposition from elemental targets was used to create Fe–B composition spread type thin film materials libraries on thermally oxidized 4-in. Si wafers. The materials libraries consisting of wedge-type multilayer thin films were annealed at 500 or 700 °C to transform the multilayers into multiphase alloys. The libraries were characterized by nuclear reaction analysis, Rutherford backscattering, nanoindentation, vibrating sample magnetometry, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Young's modulus and hardness values were related to the annealing parameters, structure and composition of the films. The magnetic properties of the films were improved by annealing in a H2 atmosphere, showing a more than tenfold decrease in the coercive field values in comparison to those of the vacuum-annealed films. The hardness values increased from 8 to 18 GPa when the annealing temperature was increased from 500 to 700 °C. The appearance of Fe2B phases, as revealed by XRD and TEM, had a significant effect on the mechanical properties of the films. PMID:27877435

An investigation of Au/Ti multilayer thin-films: surface morphology, structure and interfacial/surface migration of constituents under applied thermal stress

NASA Astrophysics Data System (ADS)

Senevirathne, Indrajith; Kemble, Eric; Lavoie, John

2014-03-01

Multilayer thin films are ubiquitous in industry. Au/Ti/substrate is unique due to possible biological applications in proof of concept devices. Material used for substrates include borosilicate glass, and quartz. Typical Ti depositions on substrates give rise to Stanski-Krastonov (SK) like growth while Frank-van der Merwe (FM) like growth is preferred. Ti films with thickness of ~ 100nm were deposited onto varying substrates using a thermal evaporator. The additional Au layer is then deposited via magnetron sputter deposition at 100mtorr at low deposition rates (~ 1ML/min) onto the Ti thin film. These systems were annealed at varying temperatures and at different durations. Systems were investigated via AFM (Atomic Force Microscopy) probes to examine the surface morphology, and structure. Further, the ambient contamination and elemental distribution/diffusion at annealing was investigated via Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX). PASSHE FPDC Annual Grant (LOU # 2010-LHU-03)

Ultrathin planar graphene supercapacitors.

PubMed

Yoo, Jung Joon; Balakrishnan, Kaushik; Huang, Jingsong; Meunier, Vincent; Sumpter, Bobby G; Srivastava, Anchal; Conway, Michelle; Reddy, Arava Leela Mohana; Yu, Jin; Vajtai, Robert; Ajayan, Pulickel M

2011-04-13

With the advent of atomically thin and flat layers of conducting materials such as graphene, new designs for thin film energy storage devices with good performance have become possible. Here, we report an "in-plane" fabrication approach for ultrathin supercapacitors based on electrodes comprised of pristine graphene and multilayer reduced graphene oxide. The in-plane design is straightforward to implement and exploits efficiently the surface of each graphene layer for energy storage. The open architecture and the effect of graphene edges enable even the thinnest of devices, made from as grown 1-2 graphene layers, to reach specific capacities up to 80 μFcm(-2), while much higher (394 μFcm(-2)) specific capacities are observed multilayer reduced graphene oxide electrodes. The performances of devices with pristine as well as thicker graphene-based structures are examined using a combination of experiments and model calculations. The demonstrated all solid-state supercapacitors provide a prototype for a broad range of thin-film based energy storage devices.

Fabrication and design of vanadium oxide microbolometer

NASA Astrophysics Data System (ADS)

Abdel-Rahman, M.; Al-Khalli, N.; Zia, M. F.; Alduraibi, M.; Ilahi, B.; Awad, E.; Debbar, N.

2017-02-01

Vanadium oxide (VxOy) multilayer sandwich structures previously studied by our group were found to yield a sensitive thermometer thin film material suitable for microbolometer applications. In this work, we aim to estimate the performance of a proposed air-bridge microbolometer configuration based on VxOy multilayer sandwich structure thermometer thin films. For this purpose, a microbolometer was fabricated on silicon (Si) substrate covered with a silicon nitride (Si3N4) insulating layer using VxOy thermometer thin film material. The fabricated microbolometer was patterned using electron-beam lithography and liftoff techniques and it was characterized in terms of its voltage repsonsivity (Rv), signal to noise ratio (SNR), noise equivalent power (NEP) and detectivity D*. A model was then developed by the aid of numerical optical/thermal simulations and experimentally measured parameters to estimate the performance of the microbolometer when fabricated in an air-bridge configuration. The estimated D* was found to be 1.55×107 cm.√Hz/ W.

Burning Graphene Layer-by-Layer

PubMed Central

Ermakov, Victor A.; Alaferdov, Andrei V.; Vaz, Alfredo R.; Perim, Eric; Autreto, Pedro A. S.; Paupitz, Ricardo; Galvao, Douglas S.; Moshkalev, Stanislav A.

2015-01-01

Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in “cold-wall” reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material. PMID:26100466

Exploring the performance of thin-film superconducting multilayers as kinetic inductance detectors for low-frequency detection

NASA Astrophysics Data System (ADS)

Zhao, Songyuan; Goldie, D. J.; Withington, S.; Thomas, C. N.

2018-01-01

We have solved numerically the diffusive Usadel equations that describe the spatially varying superconducting proximity effect in Ti-Al thin-film bi- and trilayers with thickness values that are suitable for kinetic inductance detectors (KIDs) to operate as photon detectors with detection thresholds in the frequency range of 50-90 GHz. Using Nam’s extension of the Mattis-Bardeen calculation of the superconductor complex conductivity, we show how to calculate the surface impedance for the spatially varying case, and hence the surface impedance quality factor. In addition, we calculate energy-and spatially-averaged quasiparticle lifetimes at temperatures well-below the transition temperature and compare to calculation in Al. Our results for the pair-breaking threshold demonstrate differences between bilayers and trilayers with the same total film thicknesses. We also predict high quality factors and long multilayer-averaged quasiparticle recombination times compared to thin-film Al. Our calculations give a route for designing KIDs to operate in this scientifically-important frequency regime.

Non-destructive evaluation of nano-sized structure of thin film devices by using small angle neutron scattering.

PubMed

Shin, E J; Seong, B S; Choi, Y; Lee, J K

2011-01-01

Nano-sized multi-layers copper-doped SrZrO3, platinum (Pt) and silicon oxide (SiO2) on silicon substrates were prepared by dense plasma focus (DPF) device with the high purity copper anode tip and analyzed by using small angle neutron scattering (SANS) to establish a reliable method for the non-destructive evaluation of the under-layer structure. Thin film was well formed at the time-to-dip of 5 microsec with stable plasma of DPF. Several smooth intensity peaks were periodically observed when neutron beam penetrates the thin film with multi-layers perpendicularly. The platinum layer is dominant to intensity peaks, where the copper-doped SrZnO3 layer next to the platinum layer causes peak broadening. The silicon oxide layer has less effect on the SANS spectra due to its relative thick thickness. The SANS spectra shows thicknesses of platinum and copper-doped SrZnO3 layers as 53 and 25 nm, respectively, which are well agreement with microstructure observation.

Rate- and Temperature-Dependent Material Behavior of a Multilayer Polymer Battery Separator

NASA Astrophysics Data System (ADS)

Avdeev, Ilya; Martinsen, Michael; Francis, Alex

2014-01-01

Designing battery packs for safety in automotive applications requires multiscale modeling, as macroscopic deformations due to impact cause the mechanical failure of individual cells on a sub-millimeter level. The separator material plays a critical role in this process, as the thinning or perforating of the separator can lead to thermal runaway and catastrophic failure of an entire battery pack. The electrochemical properties of various polymer separators have been extensively investigated; however, the dependency of mechanical properties of these thin films on various factors, such as high temperature and strain rate, has not been sufficiently characterized. In this study, the macroscopic mechanical properties of a multilayer polymer thin film used as a battery separator are studied experimentally at various temperatures, strain rates, and solvent saturations. Due to the anisotropy of the material, material testing was conducted in two perpendicular directions (machine and transverse directions). Material samples were tested in both dry and saturated conditions at several temperatures, and it was found that temperature and strain rate have a nearly linear effect on the stress experienced by the material. Additionally, saturating the separator material in a common lithium-ion solvent had softened it and had a positive effect on its toughness. The experimental results obtained in this study can be used to develop mathematical constitutive models of the multilayer separator material for subsequent numerical simulations and design.

Enhanced carrier mobility of multilayer MoS2 thin-film transistors by Al2O3 encapsulation

NASA Astrophysics Data System (ADS)

Kim, Seong Yeoul; Park, Seonyoung; Choi, Woong

2016-10-01

We report the effect of Al2O3 encapsulation on the carrier mobility and contact resistance of multilayer MoS2 thin-film transistors by statistically investigating 70 devices with SiO2 bottom-gate dielectric. After Al2O3 encapsulation by atomic layer deposition, calculation based on Y-function method indicates that the enhancement of carrier mobility from 24.3 cm2 V-1 s-1 to 41.2 cm2 V-1 s-1 occurs independently from the reduction of contact resistance from 276 kΩ.μm to 118 kΩ.μm. Furthermore, contrary to the previous literature, we observe a negligible effect of thermal annealing on contact resistance and carrier mobility during the atomic layer deposition of Al2O3. These results demonstrate that Al2O3 encapsulation is a useful method of improving the carrier mobility of multilayer MoS2 transistors, providing important implications on the application of MoS2 and other two-dimensional materials into high-performance transistors.

An Observation of Diamond-Shaped Particle Structure in a Soya Phosphatidylcohline and Bacteriorhodopsin Composite Langmuir Blodgett Film Fabricated by Multilayer Molecular Thin Film Method

NASA Astrophysics Data System (ADS)

Tsujiuchi, Y.; Makino, Y.

A composite film of soya phosphatidylcohline (soya PC) and bacteriorhodopsin (BR) was fabricated by the multilayer molecular thin film method using fatty acid and lipid on a quartz substrate. Direct Force Microscopy (DFM), UV absorption spectra and IR absorption spectra of the film were characterized on the detail of surface structure of the film. The DFM data revealed that many rhombus (diamond-shaped) particles were observed in the film. The spectroscopic data exhibited the yield of M-intermediate of BR in the film. On our modelling of molecular configuration indicate that the coexistence of the strong inter-molecular interaction and the strong inter-molecular interaction between BR trimmers attributed to form the particles.

One-pot synthesis of nitrogen and sulfur co-doped onion-like mesoporous carbon vesicle as an efficient metal-free catalyst for oxygen reduction reaction in alkaline solution

NASA Astrophysics Data System (ADS)

Han, Ce; Bo, Xiangjie; Zhang, Yufan; Li, Mian; Guo, Liping

2014-12-01

Nitrogen and sulfur co-doped onion-like mesoporous carbon vesicle (NS-MCV) with multilayer lamellar structure is synthesized as a metal-free catalyst through a convenient and economical procedure. The synthesized materials are systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy (XPS). The characterization results demonstrate that N and S atoms can be successfully doped into the framework of MCV with little impact on the morphology and structure. The NS-MCV manifests a remarkably high electrocatalytic activity as a metal-free electrocatalyst for the oxygen reduction reaction (ORR) with mainly a four-electron transfer pathway. Moreover, in contrast to the commercially available Pt/C catalyst, the NS-MCV shows much better long-term stability and tolerance toward methanol crossover in an alkaline medium. Such excellent performances can be mainly attributed to the synergistic effect arising from the addition of N and S heteroatom, optimized S content and high surface area. The NS-MCV with a simple synthesis method may further exploited as potentially efficient and inexpensive metal-free ORR catalyst materials.

Control of Partial Coalescence of Self-Assembled Metal Nano-Particles across Lyotropic Liquid Crystals Templates towards Long Range Meso-Porous Metal Frameworks Design

PubMed Central

Dumée, Ludovic F.; Lemoine, Jean-Baptiste; Ancel, Alice; Hameed, Nishar; He, Li; Kong, Lingxue

2015-01-01

The formation of purely metallic meso-porous metal thin films by partial interface coalescence of self-assembled metal nano-particles across aqueous solutions of Pluronics triblock lyotropic liquid crystals is demonstrated for the first time. Small angle X-ray scattering was used to study the influence of the thin film composition and processing conditions on the ordered structures. The structural characteristics of the meso-structures formed demonstrated to primarily rely on the lyotropic liquid crystal properties while the nature of the metal nano-particles used as well as the their diameters were found to affect the ordered structure formation. The impact of the annealing temperature on the nano-particle coalescence and efficiency at removing the templating lyotropic liquid crystals was also analysed. It is demonstrated that the lyotropic liquid crystal is rendered slightly less thermally stable, upon mixing with metal nano-particles and that low annealing temperatures are sufficient to form purely metallic frameworks with average pore size distributions smaller than 500 nm and porosity around 45% with potential application in sensing, catalysis, nanoscale heat exchange, and molecular separation. PMID:28347094

Influences of the residual argon gas and thermal annealing on Ta2O5 and SiO2 thin film filters

NASA Astrophysics Data System (ADS)

Liu, Wen-Jen; Chen, Chih-Min; Lai, Yin-Chieh

2005-04-01

Ion beam assisted deposition (IBAD) technique had widely used for improving stacking density and atomic mobility of thin films in many applications, especially adopted in optical film industries. Tantalum pentaoxide (Ta2O5) and silicon oxides (SiO2) optical thin films were deposited on the quartz glass substrate by using argon ion beam assisted deposition, and the influences of the residual argon gas and thermal annealing processes on the optical property, stress, compositional and microstructure evolution of the thin films were investigated in this study. Ta2O5 thin films were analyzed by XPS indicated that the ratio value of oxygen to tantalum was insufficient, at the same time, the residual argon gas in the thin films might result in film and device instabilities. Adopting oxygen-thermal annealing treatment at the temperature of 425°C, the thin films not only decreased the residual argon gas and the surface roughness, but also provided the sufficient stoichiometric ratio. Simultaneously, microstructure examination indicated few nano-crystallized structures and voids existed in Ta2O5 thin films, and possessed reasonable refractive index and lower extinction coefficient. By the way, we also suggested the IBAD system using the film compositional gas ion beam to replace the argon ion beam for assisting deposited optical films. The designed (HL)6H6LH(LH)6 multi-layers indicated higher insertion loss than the designed (HL)68H(LH)6 multi-layers. Therefore, using the high refractive index as spacer material represented lower insertion loss.

Highly ductile multilayered films by layer-by-layer assembly of oppositely charged polyurethanes for biomedical applications.

PubMed

Podsiadlo, Paul; Qin, Ming; Cuddihy, Meghan; Zhu, Jian; Critchley, Kevin; Kheng, Eugene; Kaushik, Amit K; Qi, Ying; Kim, Hyoung-Sug; Noh, Si-Tae; Arruda, Ellen M; Waas, Anthony M; Kotov, Nicholas A

2009-12-15

Multilayered thin films prepared with the layer-by-layer (LBL) assembly technique are typically "brittle" composites, while many applications such as flexible electronics or biomedical devices would greatly benefit from ductile, and tough nanostructured coatings. Here we present the preparation of highly ductile multilayered films via LBL assembly of oppositely charged polyurethanes. Free-standing films were found to be robust, strong, and tough with ultimate strains as high as 680% and toughness of approximately 30 MJ/m(3). These results are at least 2 orders of magnitude greater than most LBL materials presented until today. In addition to enhanced ductility, the films showed first-order biocompatibility with animal and human cells. Multilayered structures incorporating polyurethanes open up a new research avenue into the preparation of multifunctional nanostructured films with great potential in biomedical applications.

Studying Pulsed Laser Deposition conditions for Ni/C-based multi-layers

NASA Astrophysics Data System (ADS)

Bollmann, Tjeerd R. J.

2018-04-01

Nickel carbon based multi-layers are a viable route towards future hard X-ray and soft γ-ray focusing telescopes. Here, we study the Pulsed Laser Deposition growth conditions of such bilayers by Reflective High Energy Electron Diffraction, X-ray Reflectivity and Diffraction, Atomic Force Microscopy, X-ray Photoelectron Spectroscopy and cross-sectional Transmission Electron Microscopy analysis, with emphasis on optimization of process pressure and substrate temperature during growth. The thin multi-layers are grown on a treated SiO substrate resulting in Ni and C layers with surface roughnesses (RMS) of ≤0.2 nm. Small droplets resulting during melting of the targets surface increase the roughness, however, and cannot be avoided. The sequential process at temperatures beyond 300 °C results into intermixing between the two layers, being destructive for the reflectivity of the multi-layer.

Design and characterization of terahertz-absorbing nano-laminates of dielectric and metal thin films.

PubMed

Bolakis, C; Grbovic, D; Lavrik, N V; Karunasiri, G

2010-07-05

A terahertz-absorbing thin-film stack, containing a dielectric Bragg reflector and a thin chromium metal film, was fabricated on a silicon substrate for applications in bi-material terahertz (THz) sensors. The Bragg reflector is to be used for optical readout of sensor deformation under THz illumination. The THz absorption characteristics of the thin-film composite were measured using Fourier transform infrared spectroscopy. The absorption of the structure was calculated both analytically and by finite element modeling and the two approaches agreed well. Finite element modeling provides a convenient way to extract the amount of power dissipation in each layer and is used to quantify the THz absorption in the multi-layer stack. The calculation and the model were verified by experimentally characterizing the multi-layer stack in the 3-5 THz range. The measured and simulated absorption characteristics show a reasonably good agreement. It was found that the composite film absorbed about 20% of the incident THz power. The model was used to optimize the thickness of the chromium film for achieving high THz absorption and found that about 50% absorption can be achieved when film thickness is around 9 nm.

Optimizing ITO for incorporation into multilayer thin film stacks for visible and NIR applications

NASA Astrophysics Data System (ADS)

Roschuk, Tyler; Taddeo, David; Levita, Zachary; Morrish, Alan; Brown, Douglas

2017-05-01

Indium Tin Oxide, ITO, is the industry standard for transparent conductive coatings. As such, the common metrics for characterizing ITO performance are its transmission and conductivity/resistivity (or sheet resistance). In spite of its recurrent use in a broad range of technological applications, the performance of ITO itself is highly variable, depending on the method of deposition and chamber conditions, and a single well defined set of properties does not exist. This poses particular challenges for the incorporation of ITO in complex optical multilayer stacks while trying to maintain electronic performance. Complicating matters further, ITO suffers increased absorption losses in the NIR - making the ability to incorporate ITO into anti-reflective stacks crucial to optimizing overall optical performance when ITO is used in real world applications. In this work, we discuss the use of ITO in multilayer thin film stacks for applications from the visible to the NIR. In the NIR, we discuss methods to analyze and fine tune the film properties to account for, and minimize, losses due to absorption and to optimize the overall transmission of the multilayer stacks. The ability to obtain high transmission while maintaining good electrical properties, specifically low resistivity, is demonstrated. Trade-offs between transmission and conductivity with variation of process parameters are discussed in light of optimizing the performance of the final optical stack and not just with consideration to the ITO film itself.

Simulation and optimization of a soft gamma-ray concentrator using thin film multilayer structures

NASA Astrophysics Data System (ADS)

Shirazi, Farzane; Bloser, Peter F.; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.

2017-08-01

We are reporting the investigation result of using multilayer thin film structures for channeling and concentrating soft gamma rays with energies greater than 100 keV, beyond the reach of current grazing-incidence hard X-ray mirrors. This will enable future telescopes for higher energies with same mission parameters already proven by NuSTAR. A suitable arrangement of bent multilayer structures of alternating low and high-density materials will channel soft gamma-ray photons via total external reflection and then concentrate the incident radiation to a point. We present the latest results of producing Ir/Si and W/Si multilayers with the required thicknesses and smoothness by using magnetron sputter technique. In addition to experimental works, we have been working on gamma-ray tracking model of the concentrator by IDL, making use of optical properties calculated by the IMD software. This modeling allows us to calculate efficiency and track photon for different energy bands and materials and compare them with experimental result. Also, we describe combine concentrator modeling result and detector simulation by MEGAlib to archive a complete package of gamma-ray telescope simulation. This technology offers the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and providing greatly increased sensitivity for modest cost and complexity and opening the field up to balloon-borne instruments.

Aluminum induced crystallization of amorphous Ge thin films on insulating substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Ch. Kishan, E-mail: kisn@igcar.gov.in; Tah, T.; Sunitha, D. T.

2016-05-23

Aluminium (metal) induced crystallization of amorphous Ge in bilayer and multilayer Ge/Al thin films deposited on quartz substrate at temperature well below the crystallization temperature of bulk Ge is reported. The crystallization of poly-Ge proceeds via formations of dendritic crystalline Ge grains in the Al matrix. The observed phases were characterized by Raman spectroscopy and X-ray diffraction. The microstructure of Al thin film layer was found to have a profound influence on such crystallization process and formation of dendritic grains.

Multilayer and grazing incidence X-ray/EUV optics; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991

NASA Technical Reports Server (NTRS)

Hoover, Richard B. (Editor)

1992-01-01

The present conference discusses the Advanced X-ray Astrophysics Facility (AXAF) calibration by means of synchrotron radiation and its X-ray reflectivity, X-ray scattering measurements from thin-foil X-ray mirrors, lobster-eye X-ray optics using microchannel plates, space-based interferometry at EUV and soft X-ray wavelengths, a water-window imaging X-ray telescope, a graded d-spacing multilayer telescope for high energy X-ray astronomy, photographic films for the multispectral solar telescope array, a soft X-ray ion chamber, and the development of hard X-ray optics. Also discussed are X-ray spectroscopy with multilayered optics, a slit aperture for monitoring X-ray experiments, an objective double-crystal spectrometer, a Ly-alpha coronagraph/polarimeter, tungsten/boron nitride multilayers for XUV optical applications, the evaluation of reflectors for soft X-ray optics, the manufacture of elastically bent crystals and multilayer mirrors, and selective photodevices for the VUV.

Aminosilane functionalizations of mesoporous oxidized silicon for oligonucleotide synthesis and detection

PubMed Central

De Stefano, Luca; Oliviero, Giorgia; Amato, Jussara; Borbone, Nicola; Piccialli, Gennaro; Mayol, Luciano; Rendina, Ivo; Terracciano, Monica; Rea, Ilaria

2013-01-01

Direct solid phase synthesis of peptides and oligonucleotides (ONs) requires high chemical stability of the support material. In this work, we have investigated the passivation ability of porous oxidized silicon multilayered structures by two aminosilane compounds, 3-aminopropyltriethoxysilane and 3-aminopropyldimethylethoxysilane (APDMES), for optical label-free ON biosensor fabrication. We have also studied by spectroscopic reflectometry the hybridization between a 13 bases ON, directly grown on the aminosilane modified porous oxidized silicon by in situ synthesis, and its complementary sequence. Even if the results show that both devices are stable to the chemicals (carbonate/methanol) used, the porous silica structure passivated by APDMES reveals higher functionalization degree due to less steric hindrance of pores. PMID:23536541

Spectroscopic Ellipsometry Studies of Ag and ZnO Thin Films and Their Interfaces for Thin Film Photovoltaics

NASA Astrophysics Data System (ADS)

Sainju, Deepak

Many modern optical and electronic devices, including photovoltaic devices, consist of multilayered thin film structures. Spectroscopic ellipsometry (SE) is a critically important characterization technique for such multilayers. SE can be applied to measure key parameters related to the structural, optical, and electrical properties of the components of multilayers with high accuracy and precision. One of the key advantages of this non-destructive technique is its capability of monitoring the growth dynamics of thin films in-situ and in real time with monolayer level precision. In this dissertation, the techniques of SE have been applied to study the component layer materials and structures used as back-reflectors and as the transparent contact layers in thin film photovoltaic technologies, including hydrogenated silicon (Si:H), copper indium-gallium diselenide (CIGS), and cadmium telluride (CdTe). The component layer materials, including silver and both intrinsic and doped zinc oxide, are fabricated on crystalline silicon and glass substrates using magnetron sputtering techniques. These thin films are measured in-situ and in real time as well as ex-situ by spectroscopic ellipsometry in order to extract parameters related to the structural properties, such as bulk layer thickness and surface roughness layer thickness and their time evolution, the latter information specific to real time measurements. The index of refraction and extinction coefficient or complex dielectric function of a single unknown layer can also be obtained from the measurement versus photon energy. Applying analytical expressions for these optical properties versus photon energy, parameters that describe electronic transport, such as electrical resistivity and electron scattering time, can be extracted. The SE technique is also performed as the sample is heated in order to derive the effects of annealing on the optical properties and derived electrical transport parameters, as well as the intrinsic temperature dependence of these properties and parameters. One of the major achievements of this dissertation research is the characterization of the thickness and optical properties of the interface layer formed between the silver and zinc oxide layers in a back-reflector structure used in thin film photovoltaics. An understanding of the impact of these thin film material properties on solar cell device performance has been complemented by applying reflectance and transmittance spectroscopy as well as simulations of cell performance.

Multilayer Cloud Detection with the MODIS Near-Infrared Water Vapor Absorption Band

NASA Technical Reports Server (NTRS)

Wind, Galina; Platnick, Steven; King, Michael D.; Hubanks, Paul A,; Pavolonis, Michael J.; Heidinger, Andrew K.; Yang, Ping; Baum, Bryan A.

2009-01-01

Data Collection 5 processing for the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the NASA Earth Observing System EOS Terra and Aqua spacecraft includes an algorithm for detecting multilayered clouds in daytime. The main objective of this algorithm is to detect multilayered cloud scenes, specifically optically thin ice cloud overlying a lower-level water cloud, that presents difficulties for retrieving cloud effective radius using single layer plane-parallel cloud models. The algorithm uses the MODIS 0.94 micron water vapor band along with CO2 bands to obtain two above-cloud precipitable water retrievals, the difference of which, in conjunction with additional tests, provides a map of where multilayered clouds might potentially exist. The presence of a multilayered cloud results in a large difference in retrievals of above-cloud properties between the CO2 and the 0.94 micron methods. In this paper the MODIS multilayered cloud algorithm is described, results of using the algorithm over example scenes are shown, and global statistics for multilayered clouds as observed by MODIS are discussed. A theoretical study of the algorithm behavior for simulated multilayered clouds is also given. Results are compared to two other comparable passive imager methods. A set of standard cloudy atmospheric profiles developed during the course of this investigation is also presented. The results lead to the conclusion that the MODIS multilayer cloud detection algorithm has some skill in identifying multilayered clouds with different thermodynamic phases

Semiconductor devices incorporating multilayer interference regions

DOEpatents

Biefeld, Robert M.; Drummond, Timothy J.; Gourley, Paul L.; Zipperian, Thomas E.

1990-01-01

A semiconductor high reflector comprising a number of thin alternating layers of semiconductor materials is electrically tunable and may be used as a temperature insensitive semiconductor laser in a Fabry-Perot configuration.

Ablative Laser Propulsion Using Multi-Layered Material Systems

NASA Technical Reports Server (NTRS)

Nehls, Mary; Edwards, David; Gray, Perry; Schneider, T.

2002-01-01

Experimental investigations are ongoing to study the force imparted to materials when subjected to laser ablation. When a laser pulse of sufficient energy density impacts a material, a small amount of the material is ablated. A torsion balance is used to measure the momentum produced by the ablation process. The balance consists of a thin metal wire with a rotating pendulum suspended in the middle. The wire is fixed at both ends. Recently, multi-layered material systems were investigated. These multi-layered materials were composed of a transparent front surface and opaque sub surface. The laser pulse penetrates the transparent outer surface with minimum photon loss and vaporizes the underlying opaque layer.

Magnetron sputtered boron films and TI/B multilayer structures

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1993-01-01

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

Magnetron sputtered boron films and Ti/B multilayer structures

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1995-01-01

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

Magnetron sputtered boron films and TI/B multilayer structures

DOEpatents

Makowiecki, D.M.; Jankowski, A.F.

1993-04-20

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

Magnetron sputtered boron films and Ti/B multilayer structures

DOEpatents

Makowiecki, D.M.; Jankowski, A.F.

1995-02-14

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence. 6 figs.

Semiconductor devices incorporating multilayer interference regions

DOEpatents

Biefeld, R.M.; Drummond, T.J.; Gourley, P.L.; Zipperian, T.E.

1987-08-31

A semiconductor high reflector comprising a number of thin alternating layers of semiconductor materials is electrically tunable and may be used as a temperature insensitive semiconductor laser in a Fabry-Perot configuration. 8 figs.

Multilayer thin film design as far ultraviolet polarizers

NASA Technical Reports Server (NTRS)

Kim, Jongmin; Zukic, Muamer; Torr, Douglas T.

1993-01-01

We use a concept of induced transmission and absorption to design multilayer thin film reflection polarizers in the FUV region. We achieve high s-polarization reflectance and a high degree of polarization by means of a MgF2/Al/MgF2 three layer structure on an opaque thick film of aluminum as the substrate. For convenience they are designed at a 45 deg angle of incidence. For example, our polarizer designed for the Lyman-alpha line (121.6 nm) has 88.67 percent reflectance for the s-polarization case, and 1.21 percent for the p-polarization case, with a degree of polarization of 97.31 percent. If we make a double surface polarizer with this design, it will have a degree of polarization of 99.96 percent and s-polarization throughput of 78.62 percent.

Modelling and analysis of the stress distribution in a multi-thin film system Pt/USG/Si

NASA Astrophysics Data System (ADS)

Yao, W. Z.; Roqueta, F.; Craveur, J. C.; Belhenini, S.; Gardes, P.; Tougui, A.

2018-04-01

Residual stress analysis is commonly achieved through curvature measurement with the help of Stoney’s formula. However, this conventional approach is inadequate for multi-layer thin film systems, which are widely used in today’s microelectronics. Also, for the thin film case, the residual stress is composed of thermal stress and intrinsic stress. Measuring the wafer curvature at room temperature provides a value for the average stresses in the layer, the two components cannot be distinguished by the existing methodologies of curvature measurement. To alleviate these problems, a modified curvature method combining finite element (FE) modelling is proposed to study the stress distribution in a Pt/USG/Si structure. A 2D FE model is firstly built in order to calculate the thermal stress in the multilayer structure, the obtained thermal stresses in respective films are verified by an analytical model. Then, we calculate the warpage of the multilayer structure by considering the intrinsic stress in the respective films. The residual stresses in the films are determined by minimizing the difference between the simulated warpage and that of experimental measurement. The proposed approach can be used to calculate not only the average residual stress but also thermal and intrinsic stress components in the USG and Platinum films. The obtained residual and intrinsic stresses from a numerical model are compared with the values of other studies. There is no limitation for the application of our methodologies regarding the number of the layers in the stack.

Broadband planar multilayered absorbers tuned by VO2 phase transition

NASA Astrophysics Data System (ADS)

Peng, Hao; Ji, Chunhui; Lu, Lulu; Li, Zhe; Li, Haoyang; Wang, Jun; Wu, Zhiming; Jiang, Yadong; Xu, Jimmy; Liu, Zhijun

2017-08-01

The metal-insulator transition makes vanadium dioxide an attractive material for developing reconfigurable optoelectronic components. Here we report on dynamically tunable broadband absorbers consisting of planar multilayered thin films. By thermally triggering the phase transition of vanadium dioxide, the effective impedance of multilayered structures is tuned in or out of the condition of impedance matching to free-space, leading to switchable broadband absorptions. Two types of absorbers are designed and demonstrated by using either the insulating or metallic state of vanadium dioxide at the impedance matched condition. The planar multilayered absorbers exhibit tunable absorption bands over the wavelength ranges of 5-9.3 μm and 3.9-8.2 μm, respectively. A large modulation depth up to 88% is measured. The demonstrated broadband absorbance tunability is of potential interest for reconfigurable bolometric sensing, camouflaging, and modulation of mid-infrared lights.

Multilayer coating of optical substrates by ion beam sputtering

NASA Astrophysics Data System (ADS)

Daniel, M. V.; Demmler, M.

2017-10-01

Ion beam sputtering is well established in research and industry, despite its relatively low deposition rates compared to electron beam evaporation. Typical applications are coatings of precision optics, like filters, mirrors and beam splitter. Anti-reflective or high-reflective multilayer stacks benefit from the high mobility of the sputtered particles on the substrate surface and the good mechanical characteristics of the layers. This work gives the basic route from single layer optimization of reactive ion beam sputtered Ta2O5 and SiO2 thin films towards complex multilayer stacks for high-reflective mirrors and anti-reflective coatings. Therefore films were deposited using different oxygen flow into the deposition chamber Afterwards, mechanical (density, stress, surface morphology, crystalline phases) and optical properties (reflectivity, absorption and refractive index) were characterized. These knowledge was used to deposit a multilayer coating for a high reflective mirror.

Maximum screening fields of superconducting multilayer structures

DOE PAGES

Gurevich, Alex

2015-01-07

Here, it is shown that a multilayer comprised of alternating thin superconducting and insulating layers on a thick substrate can fully screen the applied magnetic field exceeding the superheating fields H s of both the superconducting layers and the substrate, the maximum Meissner field is achieved at an optimum multilayer thickness. For instance, a dirty layer of thickness ~0.1 μm at the Nb surface could increase H s ≃ 240 mT of a clean Nb up to H s ≃ 290 mT. Optimized multilayers of Nb 3Sn, NbN, some of the iron pnictides, or alloyed Nb deposited onto the surfacemore » of the Nb resonator cavities could potentially double the rf breakdown field, pushing the peak accelerating electric fields above 100 MV/m while protecting the cavity from dendritic thermomagnetic avalanches caused by local penetration of vortices.« less

Inkjet-printed Polyvinyl Alcohol Multilayers.

PubMed

Salaoru, Iulia; Zhou, Zuoxin; Morris, Peter; Gibbons, Gregory J

2017-05-11

Inkjet printing is a modern method for polymer processing, and in this work, we demonstrate that this technology is capable of producing polyvinyl alcohol (PVOH) multilayer structures. A polyvinyl alcohol aqueous solution was formulated. The intrinsic properties of the ink, such as surface tension, viscosity, pH, and time stability, were investigated. The PVOH-based ink was a neutral solution (pH 6.7) with a surface tension of 39.3 mN/m and a viscosity of 7.5 cP. The ink displayed pseudoplastic (non-Newtonian shear thinning) behavior at low shear rates, and overall, it demonstrated good time stability. The wettability of the ink on different substrates was investigated, and glass was identified as the most suitable substrate in this particular case. A proprietary 3D inkjet printer was employed to manufacture polymer multilayer structures. The morphology, surface profile, and thickness uniformity of inkjet-printed multilayers were evaluated via optical microscopy.

Multilayer porous structures of HVPE and MOCVD grown GaN for photonic applications

NASA Astrophysics Data System (ADS)

Braniste, T.; Ciers, Joachim; Monaico, Ed.; Martin, D.; Carlin, J.-F.; Ursaki, V. V.; Sergentu, V. V.; Tiginyanu, I. M.; Grandjean, N.

2017-02-01

In this paper we report on a comparative study of electrochemical processes for the preparation of multilayer porous structures in hydride vapor phase epitaxy (HVPE) and metal organic chemical vapor phase deposition (MOCVD) grown GaN. It was found that in HVPE-grown GaN, multilayer porous structures are obtained due to self-organization processes leading to a fine modulation of doping during the crystal growth. However, these processes are not totally under control. Multilayer porous structures with a controlled design have been produced by optimizing the technological process of electrochemical etching in MOCVD-grown samples, consisting of five pairs of thin layers with alternating-doping profiles. The samples have been characterized by SEM imaging, photoluminescence spectroscopy, and micro-reflectivity measurements, accompanied by transfer matrix analysis and simulations by a method developed for the calculation of optical reflection spectra. We demonstrate the applicability of the produced structures for the design of Bragg reflectors.

Tracing the 4000 year history of organic thin films: From monolayers on liquids to multilayers on solidsa)

NASA Astrophysics Data System (ADS)

Greene, J. E.

2015-03-01

The recorded history of organic monolayer and multilayer thin films spans approximately 4000 years. Fatty-acid-based monolayers were deposited on water by the ancients for applications ranging from fortune telling in King Hammurabi's time (˜1800 BC, Mesopotamia) to stilling choppy waters for sailors and divers as reported by the Roman philosopher Pliny the Elder in ˜78 AD, and then much later (1774) by the peripatetic American statesman and natural philosopher Benjamin Franklin, to Japanese "floating-ink" art (suminagashi) developed ˜1000 years ago. The modern science of organic monolayers began in the late-1800s/early-1900s with experiments by Lord Rayleigh and the important development by Agnes Pockels, followed two decades later by Irving Langmuir, of the tools and technology to measure the surface tension of liquids, the surface pressure of organic monolayers deposited on water, interfacial properties, molecular conformation of the organic layers, and phase transitions which occur upon compressing the monolayers. In 1935, Katherine Blodgett published a landmark paper showing that multilayers can be synthesized on solid substrates, with controlled thickness and composition, using an apparatus now known as the Langmuir-Blodgett (L-B) trough. A disadvantage of LB films for some applications is that they form weak physisorbed bonds to the substrate. In 1946, Bigelow, Pickett, and Zisman demonstrated, in another seminal paper, the growth of organic self-assembled monolayers (SAMs) via spontaneous adsorption from solution, rather than from the water/air interface, onto SiO2 and metal substrates. SAMs are close-packed two-dimensional organic crystals which exhibit strong covalent bonding to the substrate. The first multicomponent adsorbed monolayers and multilayer SAMs were produced in the early 1980s. Langmuir monolayers, L-B multilayers, and self-assembled mono- and multilayers have found an extraordinarily broad range of applications including controlled wetting, adhesion, electrochemistry, biocompatibility, molecular recognition, biosensing, cell biology, non-linear optics, molecular electronics, solar cells, read/write/erase memory, and magnetism.

Thermoelectric Properties and Morphology of Si/SiC Thin-Film Multilayers Grown by Ion Beam Sputtering

DOE PAGES

Cramer, Corson; Farnell, Casey; Farnell, Cody; ...

2018-03-19

Multilayers (MLs) of 31 bi-layers and a 10-nm layer thickness each of Si/SiC were deposited on silicon, quartz and mullite substrates using a high-speed, ion-beam sputter deposition process. The samples deposited on the silicon substrates were used for imaging purposes and structural verification as they did not allow for accurate electrical measurement of the material. The Seebeck coefficient and the electrical resistivity on the mullite and the quartz substrates were reported as a function of temperature and used to compare the film performance. The thermal conductivity measurement was performed for ML samples grown on Si, and an average value ofmore » the thermal conductivity was used to find the figure of merit, zT, for all samples tested. X-ray diffraction (XRD) spectra showed an amorphous nature of the thin films. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the film morphology and verify the nature of the crystallinity. The mobility of the multilayer films was measured to be only 0.039 to 1.0 cm 2/Vs at room temperature. The samples were tested three times in the temperature range of 300 K to 900 K to document the changes in the films with temperature cycling. The highest Seebeck coefficient is measured for a Si/SiC multilayer system on quartz and mullite substrates and were observed at 870 K to be roughly -2600 μV/K due to a strain-induced redistribution of the states’ effect. The highest figure of merit, zT, calculated for the multilayers in this study was 0.08 at 870 K.« less

Cobalt-based multilayers with ultrathin seedlayers for perpendicular magnetic recording media

NASA Astrophysics Data System (ADS)

Peng, Wenbin

With the rapid increase in areal density in longitudinal magnetic recording, it is widely believed that the superparamagnetic limit will soon be reached. Perpendicular magnetic recording is now being seriously considered to be a candidate for the replacement. Co/Pd and Co/Pt multilayers are promising candidates because of their high anisotropy, high coercivity, high remanent squareness, and high negative nucleation field. However, Co/Pd and Co/Pt multilayers usually require thick seed layers to promote perpendicular anisotropies, which leads to large "spacing loss". In this work, different seed layers were studied and it showed that an amorphous indium tin oxide (ITO) seed layer as thin as 2nm could promote good perpendicular anisotropy. The processing parameters for Co-based multilayers such as deposition pressure, temperature, individual layer thickness, and number of bilayers were optimized to obtain better interfaces, higher coercivity, and higher anisotropies. Boron was added as dopants into Co layers to obtain better intergranular segregation and reduce the grain growth during the thin film deposition. The substrates were heated to promote the migration of boron atoms. It was proved that the addition of boron has successfully reduced the magnetic domain sizes as well as the media noise. Spin stand test showed that the CoB/Pd multilayers with 2nm ITO seed layer and 6mum thick NiFe soft underlayers deposited at 230°C gave a D50 of 340 kfci for differentiated output signals and an areal density of 11 Gb/in2 at a bit-error-rate of 10 -7. Given narrower heads, better soft underlayer, and lower flying height, the media can reach a much higher recording density.

Thermoelectric Properties and Morphology of Si/SiC Thin-Film Multilayers Grown by Ion Beam Sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cramer, Corson; Farnell, Casey; Farnell, Cody

Multilayers (MLs) of 31 bi-layers and a 10-nm layer thickness each of Si/SiC were deposited on silicon, quartz and mullite substrates using a high-speed, ion-beam sputter deposition process. The samples deposited on the silicon substrates were used for imaging purposes and structural verification as they did not allow for accurate electrical measurement of the material. The Seebeck coefficient and the electrical resistivity on the mullite and the quartz substrates were reported as a function of temperature and used to compare the film performance. The thermal conductivity measurement was performed for ML samples grown on Si, and an average value ofmore » the thermal conductivity was used to find the figure of merit, zT, for all samples tested. X-ray diffraction (XRD) spectra showed an amorphous nature of the thin films. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the film morphology and verify the nature of the crystallinity. The mobility of the multilayer films was measured to be only 0.039 to 1.0 cm 2/Vs at room temperature. The samples were tested three times in the temperature range of 300 K to 900 K to document the changes in the films with temperature cycling. The highest Seebeck coefficient is measured for a Si/SiC multilayer system on quartz and mullite substrates and were observed at 870 K to be roughly -2600 μV/K due to a strain-induced redistribution of the states’ effect. The highest figure of merit, zT, calculated for the multilayers in this study was 0.08 at 870 K.« less

Correlation Between Material Properties of Ferroelectric Thin Films and Design Parameters for Microwave Device Applications: Modeling Examples and Experimental Verification

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; VanKeuls, Fred W.; Subramanyam, Guru; Mueller, Carl H.; Romanofsky, Robert R.; Rosado, Gerardo

2000-01-01

The application of thin ferroelectric films for frequency and phase agile components is the topic of interest of many research groups worldwide. Consequently, proof-of-concepts (POC) of different tunable microwave components using either (HTS, metal)/ferroelectric thin film/dielectric heterostructures or (thick, thin) film "flip-chip" technology have been reported. Either as ferroelectric thin film characterization tools or from the point of view of circuit implementation approach, both configurations have their respective advantages and limitations. However, we believe that because of the progress made so far using the heterostructure (i.e., multilayer) approach, and due to its intrinsic features such as planar configuration and monolithic integration, a study on the correlation of circuit geometry aspects and ferroelectric material properties could accelerate the insertion of this technology into working systems. In this paper, we will discuss our study performed on circuits based on microstrip lines at frequencies above 10 GHz, where the multilayer configuration offers greater ease of insertion due to circuit's size reduction. Modeled results of relevant circuit parameters such as the characteristic impedance, effective dielectric constant, and attenuation as a function of ferroelectric film's dielectric constant, tans, and thickness, will be presented for SrTiO3 and Ba(x)Sr(1-x)TiO3 ferroelectric films. A comparison between the modeled and experimental data for some of these parameters will be presented.

Mesoporous nanocrystalline film architecture for capacitive storage devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunn, Bruce S.; Tolbert, Sarah H.; Wang, John

A mesoporous, nanocrystalline, metal oxide construct particularly suited for capacitive energy storage that has an architecture with short diffusion path lengths and large surface areas and a method for production are provided. Energy density is substantially increased without compromising the capacitive charge storage kinetics and electrode demonstrates long term cycling stability. Charge storage devices with electrodes using the construct can use three different charge storage mechanisms immersed in an electrolyte: (1) cations can be stored in a thin double layer at the electrode/electrolyte interface (non-faradaic mechanism); (2) cations can interact with the bulk of an electroactive material which then undergoesmore » a redox reaction or phase change, as in conventional batteries (faradaic mechanism); or (3) cations can electrochemically adsorb onto the surface of a material through charge transfer processes (faradaic mechanism).« less

Fabrication of mesoporous cerium dioxide films by cathodic electrodeposition.

PubMed

Kim, Young-Soo; Lee, Jin-Kyu; Ahn, Jae-Hoon; Park, Eun-Kyung; Kim, Gil-Pyo; Baeck, Sung-Hyeon

2007-11-01

Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templating agent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating.

Layer-by-layer strippable Ag multilayer films fabricated by modular assembly.

PubMed

Li, Yan; Chen, Xiaoyan; Li, Qianqian; Song, Kai; Wang, Shihui; Chen, Xiaoyan; Zhang, Kai; Fu, Yu; Jiao, Yong-Hua; Sun, Ting; Liu, Fu-Chun; Han, En-Hou

2014-01-21

We have developed a new method to fabricate multilayer films, which uses prepared thin films as modular blocks and transfer as operation mode to build up multilayer structures. In order to distinguish it from the in situ fabrication manner, this method is called modular assembly in this study. On the basis of such concept, we have fabricated a multilayer film using the silver mirror film as the modular block and poly(lactic acid) as the transfer tool. Due to the special double-layer structure of the silver mirror film, the resulting multilayer film had a well-defined stratified architecture with alternate porous/compact layers. As a consequence of the distinct structure, the interaction between the adjacent layers was so weak that the multilayer film could be layer-by-layer stripped. In addition, the top layer in the film could provide an effective protection on the morphology and surface property of the underlying layers. This suggests that if the surface of the film was deteriorated, the top layer could be peeled off and the freshly exposed surface would still maintain the original function. The successful preparation of the layer-by-layer strippable silver multilayer demonstrates that modular assembly is a feasible and effective method to build up multilayer films capable of creating novel and attractive micro/nanostructures, having great potential in the fabrication of nanodevices and coatings.

Investigation of optical properties of multilayer dielectric structures using prism-coupling technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolov, V I; Glebov, V N; Malyutin, A M

2015-09-30

A method based on resonant excitation of waveguide modes with a prism coupler is proposed for measuring the thickness and refractive index of thin-film layers in multilayer dielectric structures. The peculiarities of reflection of TE- and TM-polarised light beams from a structure comprising eleven alternating layers of zinc sulfide (ZnS) and magnesium barium fluoride (MgBaF{sub 4}), whose thicknesses are much less than the wavelength of light, are investigated. Using the mathematical model developed, we have calculated the coefficients of reflection of collimated TE and TM light beams from a multilayer structure and determined the optical constants and thicknesses of themore » structure layers. The refractive indices of the layers, obtained for TE and TM polarisation of incident light, are in good agreement. The thicknesses of ZnS and MgBaF{sub 4} layers, found for different polarisations, coincide with an accuracy of ±1%. Thus, we have demonstrated for the first time that the prism-coupling technique allows one to determine the optical properties of thin-film structures when the number of layers in the structure exceeds ten layers. (integrated optics)« less

Layer-by-layer modification of thin-film metal-semiconductor multilayers with ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Romashevskiy, S. A.; Tsygankov, P. A.; Ashitkov, S. I.; Agranat, M. B.

2018-05-01

The surface modifications in a multilayer thin-film structure (50-nm alternating layers of Si and Al) induced by a single Gaussian-shaped femtosecond laser pulse (350 fs, 1028 nm) in the air are investigated by means of atomic-force microscopy (AFM), scanning electron microscopy (SEM), and optical microscopy (OM). Depending on the laser fluence, various modifications of nanometer-scale metal and semiconductor layers, including localized formation of silicon/aluminum nanofoams and layer-by-layer removal, are found. While the nanofoams with cell sizes in the range of tens to hundreds of nanometers are produced only in the two top layers, layer-by-layer removal is observed for the four top layers under single pulse irradiation. The 50-nm films of the multilayer structure are found to be separated at their interfaces, resulting in a selective removal of several top layers (up to 4) in the form of step-like (concentric) craters. The observed phenomenon is associated with a thermo-mechanical ablation mechanism that results in splitting off at film-film interface, where the adhesion force is less than the bulk strength of the used materials, revealing linear dependence of threshold fluences on the film thickness.

Influence of metal electrodes on the response of humidity sensors coated with mesoporous silica

NASA Astrophysics Data System (ADS)

Bearzotti, Andrea

2008-01-01

Interesting effects of different metal electrodes on the behaviour of mesoporous based humidity sensors have been observed and studied by chemical characterization and electric measurements. The devices were prepared on passivated silicon slices utilizing an interdigitated structure as contacts. For comparison, the response of a device implemented on an alumina substrate has been reported. A block copolymer Pluronic F-127 has been used as the organic template and has been partially removed from the films by thermal calcination. A thin film mesoporous membrane has been deposited by dip-coating on the substrates in a sol-gel solution containing non-ionic block copolymers. Silica mesostructured films have been produced using an evaporation induced self-assembling process. The films were calcined at 150 °C to obtain the best performances in terms of stability, hysteresis and reproducibility of the response. The performance of the sensor has been found to be dependent on the film preparation method, the used electrodes and the substrate when exposed to different contents of relative humidity. Electrical characterization was performed under vacuum and dark conditions to investigate the properties of the materials in the absence of interfering chemicals, while the sensory properties were obtained in a controlled environment.

Deliberate Design of TiO2 Nanostructures towards Superior Photovoltaic Cells.

PubMed

Sun, Ziqi; Liao, Ting; Sheng, Liyuan; Kou, Liangzhi; Kim, Jung Ho; Dou, Shi Xue

2016-08-01

TiO2 nanostructures are being sought after as flexibly utilizable building blocks for the fabrication of the mesoporous thin-film photoelectrodes that are the heart of the third-generation photovoltaic devices, such as dye-sensitized solar cells (DSSCs), quantum-dot-sensitized solar cells (QDSSCs), and the recently promoted perovskite-type solar cells. Here, we report deliberate tailoring of TiO2 nanostructures for superior photovoltaic cells. Morphology engineering of TiO2 nanostructures is realized by designing synthetic protocols in which the precursor hydrolysis, crystal growth, and oligomer self-organization are precisely controlled. TiO2 nanostructures in forms varying from isolated nanocubes, nanorods, and cross-linked nanorods to complex hierarchical structures and shape-defined mesoporous micro-/nanostructures were successfully synthesized. The photoanodes made from the shape-defined mesoporous TiO2 microspheres and nanospindles presented superior performances, owing to the well-defined overall shapes and the inner ordered nanochannels, which allow not only a high amount of dye uptake, but also improved visible-light absorption. This study provides a new way to seek an optimal synthetic protocol to meet the required functionality of the nanomaterials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of ordered mesoporous alumina-doped titania films with high thermal stability and their application to high-speed passive-matrix electrochromic displays.

PubMed

Jiang, Xiangfen; Bastakoti, Bishnu Prasad; Weng, Wu; Higuchi, Tetsuya; Oveisi, Hamid; Suzuki, Norihiro; Chen, Wei-Jung; Huang, Yu-Tzu; Yamauchi, Yusuke

2013-08-12

Ordered mesoporous alumina-doped titania thin films with anatase crystalline structure were prepared by using triblock copolymer Pluronic P123 as structure-directing agent. Uniform Al doping was realized by using aluminum isopropoxide as a dopant source which can be hydrolyzed together with titanium tetraisopropoxide. Aluminum doping into the titania framework can prevent rapid crystallization to the anatase phase, thereby drastically increasing thermal stability. With increasing Al content, the crystallization temperatures tend to increase gradually. Even when the Al content doped into the framework was increased to 15 mol %, a well-ordered mesoporous structure was obtained, and the mesostructural ordering was still maintained after calcination at 550 °C. During the calcination process, large uniaxial shrinkage occurred along the direction perpendicular to the substrate with retention of the horizontal mesoscale periodicity, whereby vertically oriented nanopillars were formed in the film. The resulting vertical porosity was successfully exploited to fabricate a high-speed and high-quality passive-matrix electrochromic display by using a leuco dye. The vertical nanospace in the films can effectively prevent drifting of the leuco dye. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermo-optically tunable thin film devices

NASA Astrophysics Data System (ADS)

Domash, Lawrence H.

2003-10-01

We report advances in tunable thin film technology and demonstration of multi-cavity tunable filters. Thin film interference coatings are the most widely used optical technology for telecom filtering, but until recently no tunable versions have been known except for mechanically rotated filters. We describe a new approach to broadly tunable components based on the properties of semiconductor thin films with large thermo-optic coefficients. The technology is based on amorphous silicon deposited by plasma-enhanced chemical vapor deposition (PECVD), a process adapted for telecom applications from its origins in the flat-panel display and solar cell industries. Unlike MEMS devices, tunable thin films can be constructed in sophisticated multi-cavity, multi-layer optical designs.

Rapid Optimization of External Quantum Efficiency of Thin Film Solar Cells Using Surrogate Modeling of Absorptivity.

PubMed

Kaya, Mine; Hajimirza, Shima

2018-05-25

This paper uses surrogate modeling for very fast design of thin film solar cells with improved solar-to-electricity conversion efficiency. We demonstrate that the wavelength-specific optical absorptivity of a thin film multi-layered amorphous-silicon-based solar cell can be modeled accurately with Neural Networks and can be efficiently approximated as a function of cell geometry and wavelength. Consequently, the external quantum efficiency can be computed by averaging surrogate absorption and carrier recombination contributions over the entire irradiance spectrum in an efficient way. Using this framework, we optimize a multi-layer structure consisting of ITO front coating, metallic back-reflector and oxide layers for achieving maximum efficiency. Our required computation time for an entire model fitting and optimization is 5 to 20 times less than the best previous optimization results based on direct Finite Difference Time Domain (FDTD) simulations, therefore proving the value of surrogate modeling. The resulting optimization solution suggests at least 50% improvement in the external quantum efficiency compared to bare silicon, and 25% improvement compared to a random design.

Structure and method for controlling band offset and alignment at a crystalline oxide-on-semiconductor interface

DOEpatents

McKee, Rodney A.; Walker, Frederick J.

2003-11-25

A crystalline oxide-on-semiconductor structure and a process for constructing the structure involves a substrate of silicon, germanium or a silicon-germanium alloy and an epitaxial thin film overlying the surface of the substrate wherein the thin film consists of a first epitaxial stratum of single atomic plane layers of an alkaline earth oxide designated generally as (AO).sub.n and a second stratum of single unit cell layers of an oxide material designated as (A'BO.sub.3).sub.m so that the multilayer film arranged upon the substrate surface is designated (AO).sub.n (A'BO.sub.3).sub.m wherein n is an integer repeat of single atomic plane layers of the alkaline earth oxide AO and m is an integer repeat of single unit cell layers of the A'BO.sub.3 oxide material. Within the multilayer film, the values of n and m have been selected to provide the structure with a desired electrical structure at the substrate/thin film interface that can be optimized to control band offset and alignment.

Sound transmission through finite lightweight multilayered structures with thin air layers.

PubMed

Dijckmans, A; Vermeir, G; Lauriks, W

2010-12-01

The sound transmission loss (STL) of finite lightweight multilayered structures with thin air layers is studied in this paper. Two types of models are used to describe the vibro-acoustic behavior of these structures. Standard transfer matrix method assumes infinite layers and represents the plane wave propagation in the layers. A wave based model describes the direct sound transmission through a rectangular structure placed between two reverberant rooms. Full vibro-acoustic coupling between rooms, plates, and air cavities is taken into account. Comparison with double glazing measurements shows that this effect of vibro-acoustic coupling is important in lightweight double walls. For infinite structures, structural damping has no significant influence on STL below the coincidence frequency. In this frequency region, the non-resonant transmission or so-called mass-law behavior dominates sound transmission. Modal simulations suggest a large influence of structural damping on STL. This is confirmed by experiments with double fiberboard partitions and sandwich structures. The results show that for thin air layers, the damping induced by friction and viscous effects at the air gap surfaces can largely influence and improve the sound transmission characteristics.

Microelectronic superconducting device with multi-layer contact

DOEpatents

Wellstood, Frederick C.; Kingston, John J.; Clarke, John

1993-01-01

A microelectronic component comprising a crossover is provided comprising a substrate, a first high T.sub.c superconductor thin film, a second insulating thin film comprising SrTiO.sub.3 ; and a third high T.sub.c superconducting film which has strips which crossover one or more areas of the first superconductor film. An insitu method for depositing all three films on a substrate is provided which does not require annealing steps. The photolithographic process is used to separately pattern the high T.sub.c superconductor thin films.

Thin film photovoltaic device

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1982-01-01

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

Microelectronic superconducting device with multi-layer contact

DOEpatents

Wellstood, F.C.; Kingston, J.J.; Clarke, J.

1993-10-26

A microelectronic component comprising a crossover is provided comprising a substrate, a first high T[sub c] superconductor thin film, a second insulating thin film comprising SrTiO[sub 3] ; and a third high T[sub c] superconducting film which has strips which crossover one or more areas of the first superconductor film. An in situ method for depositing all three films on a substrate is provided which does not require annealing steps. The photolithographic process is used to separately pattern the high T[sub c] superconductor thin films. 14 figures.

Thermal conductivity of SrVO3-SrTiO3 thin films: Evidence of intrinsic thermal resistance at the interface between oxide layers

NASA Astrophysics Data System (ADS)

Katsufuji, T.; Saiki, T.; Okubo, S.; Katayama, Y.; Ueno, K.

2018-05-01

By using a technique of thermoreflectance that can precisely measure the thermal conductivity of thin films, we found that the thermal conductivity of SrVO3-SrTiO3 multilayer thin films normal to the surface was substantially reduced by decreasing the thickness of each layer. This indicates that a large intrinsic thermal resistance exists at the interface between SrVO3 and SrTiO3 in spite of the similar phononic properties for these two compounds.

Fabrication of multilayer TiO{sub 2} thin films for dye-sensitized solar cells with high conversion efficiency by electrophoresis deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Ho; Chen, Wei-An; Su, Hung-Ting

2010-01-15

This research coats a commercial TiO{sub 2} nanoparticle Degussa P25 with good roundness and size uniformity on an indium tin oxide (ITO) glass substrate and to be photoelectrical electrode by electrophoresis deposition. It combined with dye N719, electrolyte I{sup -}/ I{sub 3}{sup -} and counter-electrode of Pt layer to produce dye-sensitized solar cells (DSSCs). Through the electrophoretic technique, a multilayer film of an appropriate thickness is deposited in the suspension containing TiO{sub 2} nanoparticles and isopropanol. In this process, electric current, voltage, and the number of deposition cycles are well controlled to obtain a single TiO{sub 2} film of aroundmore » 3.3 {mu}m thick. Stacking is then performed to obtain a multilayer-typed TiO{sub 2} film of around 12 {mu}m thick. As the sintering temperature reaches 400 C, the prepared multilayer TiO{sub 2} film with a good compactness can increase the dye adsorption capability of the thin film and enhance its adsorption percentage. In addition, the heat treatment will transfer a portion of the rutile crystalline into the anatase crystalline, resulting in better material properties for DSSCs application. DSSCs produced are exposed to metal halide lamp and their energy conversion efficiency is measured. The I-V curve of the produced DSSCs shows that it has an excellent energy conversion efficiency of 6.9%. (author)« less

Ultra-thin multilayer capacitors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renk, Timothy Jerome; Monson, Todd C.

2009-06-01

The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report detailsmore » some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.« less

Forming aspheric optics by controlled deposition

DOEpatents

Hawryluk, A.M.

1998-04-28

An aspheric optical element is disclosed formed by depositing material onto a spherical surface of an optical element by controlled deposition to form an aspheric surface of desired shape. A reflecting surface, single or multi-layer, can then be formed on the aspheric surface by evaporative or sputtering techniques. Aspheric optical elements are suitable for deep ultra-violet (UV) and x-ray wavelengths. The reflecting surface may, for example, be a thin ({approx}100 nm) layer of aluminum, or in some cases the deposited modifying layer may function as the reflecting surface. For certain applications, multi-layer reflective surfaces may be utilized, such as chromium-carbon or tungsten-carbon multi-layer, with the number of layers and thickness being determined by the intended application. 4 figs.

Forming aspheric optics by controlled deposition

DOEpatents

Hawryluk, Andrew M.

1998-01-01

An aspheric optical element formed by depositing material onto a spherical surface of an optical element by controlled deposition to form an aspheric surface of desired shape. A reflecting surface, single or multi-layer, can then be formed on the aspheric surface by evaporative or sputtering techniques. Aspheric optical elements are suitable for deep ultra-violet (UV) and x-ray wavelengths. The reflecting surface may, for example, be a thin (.about.100 nm) layer of aluminum, or in some cases the deposited modifying layer may function as the reflecting surface. For certain applications, multi-layer reflective surfaces may be utilized, such as chromium-carbon or tungsten-carbon multi-layer, with the number of layers and thickness being determined by the intended application.

Tuning the effective parameters in (Ta/Cu/[Ni/Co]x/Ta) multilayers with perpendicular magnetic anisotropy

NASA Astrophysics Data System (ADS)

Ayareh, Zohreh; Moradi, Mehrdad; Mahmoodi, Saman

2018-06-01

In this paper, we report perpendicular magnetic anisotropy (PMA) in a (Ta/Cu/[Ni/Co]x/Ta) multilayers structure. These typical structures usually include a multilayer of ferromagnetic and transition metal thin films. Usually, magnetic anisotropy is characterized by magnetization loops determined by magnetometer or magneto-optical Kerr effect (MOKE). The interface between ferromagnetic and metallic layers plays an important role in magnetic anisotropy evolution from out-of-plane to in-plane in (Ta/Cu/[Ni/Co]/Ta) structure. Obtained results from MOKE and magnetometry of these samples show that they have different easy axes due to change in thickness of Cu as spacer layer and difference in number of repetition of [Ni/Co] stacks.

Freestanding and Reactive Thin Films Fabricated by Covalent Layer-by-Layer Assembly and Subsequent Lift-Off of Azlactone-Containing Polymer Multilayers

PubMed Central

Buck, Maren E.

2010-01-01

We report an approach to the fabrication of freestanding and amine-reactive thin films that is based on the reactive layer-by-layer assembly and subsequent lift-off of azlactone-containing polymer multilayers. We demonstrate that covalently crosslinked multilayers fabricated using the azlactone-functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) and a primary amine-containing polymer [poly(ethyleneimine) (PEI)] can be delaminated from planar glass and silicon surfaces by immersion in mildly acidic aqueous environments to yield flexible freestanding membranes. These freestanding membranes are robust and can withstand exposure to strong acid, strong base, or incubation in high ionic strength solutions that typically lead to the disruption and erosion of polymer multilayers assembled by reversible weak interactions (e.g., ‘polyelectrolyte multilayers’ assembled by electrostatic interactions or hydrogen bonding). We demonstrate further that these PEI/PVDMA assemblies contain residual reactive azlactone functionality that can be exploited to chemically modify the films (either directly after fabrication or after they have been lifted off of the substrates on which they were fabricated) using a variety of amine-functionalized small molecules. These freestanding membranes can also be transferred readily onto other objects (for example, onto the surfaces of planar substrates containing holes or pores) to fabricate suspended polymer membranes and other film-functionalized interfaces. In addition to planar, two-dimensional freestanding films, this approach can be used to fabricate and isolate three-dimensional freestanding membranes (e.g., curved films or tubes) by layer-by-layer assembly on, and subsequent lift-off from, the surfaces of topologically complex substrates (e.g., the curved ends of glass tubing, etc.). The results of this investigation, when combined, suggest the basis of methods for the fabrication of stable, chemically-reactive, and flexible polymer thin films and membranes of potential utility in a variety of fundamental and applied contexts. PMID:20857952

Next-generation all-silica coatings for UV applications

NASA Astrophysics Data System (ADS)

Melninkaitis, A.; Grinevičiūtė, L.; Abromavičius, G.; Mažulė, L.; Smalakys, L.; Pupka, E.; Š čiuka, M.; Buzelis, R.; Kičas, S.

2017-11-01

Band-gap and refractive index are known as fundamental properties determining intrinsic optical resistance of multilayer dielectric coatings. By considering this fact we propose novel approach to manufacturing of interference thin films, based on artificial nano-structures of modulated porosity embedded in high band-gap matrix. Next generation all-silica mirrors were prepared by GLancing Angle Deposition (GLAD) using electron beam evaporation. High reflectivity (HR) was achieved by tailoring the porosity of highly resistant silica material during the thin film deposition process. Furthermore, the proposed approach was also demonstrated to work well in case of anti-reflection (AR) coatings. Conventional HR HfO2 and SiO2 as well as AR Al2O3 and SiO2 multilayers produced by Ion Beam Sputtering (IBS) were used as reference coatings. Damage performance of experimental coatings was also analyzed. All-silica based GLAD approach resulted in significant improvement of intrinsic laser damage resistance properties if compared to conventional coatings. Besides laser damage testing, other characteristics of experimental coatings are analyzed and discussed - reflectance, surface roughness and optical scattering. We believe that reported concept can be expanded to virtually any design of thin film coatings thus opening a new way of next generation highly resistant thin films well suited for high power and UV laser applications.

Femtosecond laser processing of NiPd single and 5x(Ni/Pd) multilayer thin films

NASA Astrophysics Data System (ADS)

Petrović, S.; Gaković, B.; Zamfirescu, M.; Radu, C.; Peruško, D.; Radak, B.; Ristoscu, C.; Zdravković, S.; Luculescu, C. L.; Mihailescu, I. N.

2017-09-01

Modification of single and complex nickel-palladium samples by laser processing in the femtosecond time domain was studied. The samples were processed by focused Ti:Sapphire laser beam (Clark CPA-2101) with 775 nm laser wavelength, 2 kHz repetition rate, 200 fs pulse duration. The laser-induced morphological modifications have shown dependence on the applied fluences and number of laser pulses. The formed surface nanostructures on the single NiPd/Si and multilayer 5x(Ni/Pd)/Si systems are compared with individual Ni and Pd thin films. The results show an increase in surface roughness, formation of parallel periodic surface structures, appearance of hydrodynamic features and ablation of surface material. At low number of pulses (less than 10 pulses) and low pulse energies range (not over 1.7 μJ), the two types of laser-induced periodic surface structure (LIPSS) can be observed: low and high spatial frequency LIPSS (HSFL and LSFL). For all samples, the measured LSFL periods were 720 nm for the ripples created solely on thin film surfaces during the single pulse action. In the case of the multi-pulse irradiation, the periodicities of created LSFLs on the all investigated thin films have shown tendency to reduction with increasing of pulse energies.

Structural studies of zirconium doped Ba{sub 0.70}Sr{sub 0.30}TiO{sub 3} lead free ferroelectric thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Sarita, E-mail: sss.sharmasarita@gmail.com; Ram, Mast; Thakur, Shilpa

2016-05-06

Ba{sub 0.7}Sr{sub 0.3}(Zr{sub x}Ti{sub 1-x})O{sub 3}(BSZT, x=0,0.05,0.10,0.15,0.20) thin films were prepared by using sol gel method. Structural and microstructural properties were studied by using XRD, Raman Spectroscopy and atomic force microscopy (AFM) respectively. XRD and Raman Spectroscopy show the presence of tetragonal phase in multilayer BSZT thin film. The experimental results demonstrate that structural and microstructural properties of BSZT thin film were significantly dependent on variation of Zr content.

Extraordinary Corrosion Protection from Polymer-Clay Nanobrick Wall Thin Films.

PubMed

Schindelholz, Eric J; Spoerke, Erik D; Nguyen, Hai-Duy; Grunlan, Jaime C; Qin, Shuang; Bufford, Daniel C

2018-06-20

Metals across all industries demand anticorrosion surface treatments and drive a continual need for high-performing and low-cost coatings. Here we demonstrate polymer-clay nanocomposite thin films as a new class of transparent conformal barrier coatings for protection in corrosive atmospheres. Films assembled via layer-by-layer deposition, as thin as 90 nm, are shown to reduce copper corrosion rates by >1000× in an aggressive H 2 S atmosphere. These multilayer nanobrick wall coatings hold promise as high-performing anticorrosion treatment alternatives to costlier, more toxic, and less scalable thin films, such as graphene, hexavalent chromium, or atomic-layer-deposited metal oxides.

X-ray optics made from thin plastic foils

NASA Astrophysics Data System (ADS)

Schnopper, Herbert W.; Silver, Eric H.; Ingram, Russell H.; Christensen, Finn E.; Hussain, Ahsen M.; Barbera, Marco; Romaine, Suzanne E.; Collura, Alfonso; Kenter, Almus T.; Bandler, Simon; Murray, Stephen S.

1999-09-01

New design concepts and materials can be used to produce very lightweight, thin foil approximations, to Wolter I and other x-ray optics. Structures are designed around a central hub and spacers that connect one spoked wheels. Figure defining, thin pins span the distance between the wheels. Thin, metal coated or multilayered, plastic foils can be formed into cones, cylinders or spirals for x-ray telescopes or lenses. Imaging and spectroscopic data obtained with x- ray lenses are presented and they indicate that a 60 cm diameter, 4.65 m focal length x-ray telescope can have a half power diameter of < 2 arcmin.

Inkjet Printing NiO-Based p-Type Dye-Sensitized Solar Cells.

PubMed

Brisse, R; Faddoul, R; Bourgeteau, T; Tondelier, D; Leroy, J; Campidelli, S; Berthelot, T; Geffroy, B; Jousselme, B

2017-01-25

Fabrication at low cost of transparent p-type semiconductors with suitable electronic properties is essential toward the scalability of many electronic devices, especially for photovoltaic and photocatalytic applications. In this context, the synthesis of mesoporous NiO films through inkjet printing of a sol-gel ink was investigated for the first time. Nickel chloride and Pluronic F-127, used as nickel oxide precursor and pore-forming agent, respectively, were formulated in a water/ethanol mixture to prepare a jettable ink for Dimatix printer. Multilayer NiO films were formed, and different morphologies could be obtained by playing on the interlayer thermal treatment. At low temperature (30 °C), a porous nanoparticulate-nanofiber dual-pore structure was observed. On the other hand, with a high temperature treatment (450 °C), nanoparticulate denser films without any dual structure were obtained. The mechanism for NiO formation during the final sintering step, investigated by means of X-ray photolectron spectroscopy, shows that a Ni(OH) 2 species is an intermediate between NiCl 2 and NiO. The different morphologies and thicknesses of the NiO films were correlated to their performance in a p-DSSC configuration, using a new push-pull dye (so-called "RBG-174") and an iodine-based electrolyte. Moreover, the positive impact of a nanometric NiO x layer deposited by spin-coating and introduced between FTO and the NiO mesoporous network is highlighted in the present work. The best results were obtained with NiO x /four layer-NiO mesoporous photocathodes of 860 nm, with a current density at the short circuit of 3.42 mA cm -2 (irradiance of 100 mW cm -2 spectroscopically distributed following AM 1.5).

CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles exhibit fast and selective adsorption of arsenic with high adsorption capacity

PubMed Central

Yang, Ji-Chun; Yin, Xue-Bo

2017-01-01

In this study, we report the synthesis and application of mesoporous CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles (MNPs) for the simultaneous removal of inorganic arsenic (iAs). The hybrid adsorbent had a core-shell and mesoporous structure with an average diameter of 260 nm. The nanoscale size and mesoporous character impart a fast adsorption rate and high adsorption capacity for iAs. In total, 0.1 mg L−1 As(V) and As(III) could be adsorbed within 2 min, and the maximum adsorption capacities were 114.8 mg g−1 for As(V) and 143.6 mg g−1 for As(III), higher than most previously reported adsorbents. The anti-interference capacity for iAs adsorption was improved by the electrostatic repulsion and size exclusion effects of the MIL-100(Fe) shell, which also decreased the zero-charge point of the hybrid absorbent for a broad pH adsorption range. The adsorption mechanisms of iAs on the MNPs are proposed. An Fe-O-As structure was formed on CoFe2O4@MIL-100(Fe) through hydroxyl substitution with the deprotonated iAs species. Monolayer adsorption of As(V) was observed, while hydrogen bonding led to the multi-layer adsorption of neutral As(III) for its high adsorption capacity. The high efficiency and the excellent pH- and interference-tolerance capacities of CoFe2O4@MIL-100(Fe) allowed effective iAs removal from natural water samples, as validated with batch magnetic separation mode and a portable filtration strategy. PMID:28102334

CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles exhibit fast and selective adsorption of arsenic with high adsorption capacity

NASA Astrophysics Data System (ADS)

Yang, Ji-Chun; Yin, Xue-Bo

2017-01-01

In this study, we report the synthesis and application of mesoporous CoFe2O4@MIL-100(Fe) hybrid magnetic nanoparticles (MNPs) for the simultaneous removal of inorganic arsenic (iAs). The hybrid adsorbent had a core-shell and mesoporous structure with an average diameter of 260 nm. The nanoscale size and mesoporous character impart a fast adsorption rate and high adsorption capacity for iAs. In total, 0.1 mg L-1 As(V) and As(III) could be adsorbed within 2 min, and the maximum adsorption capacities were 114.8 mg g-1 for As(V) and 143.6 mg g-1 for As(III), higher than most previously reported adsorbents. The anti-interference capacity for iAs adsorption was improved by the electrostatic repulsion and size exclusion effects of the MIL-100(Fe) shell, which also decreased the zero-charge point of the hybrid absorbent for a broad pH adsorption range. The adsorption mechanisms of iAs on the MNPs are proposed. An Fe-O-As structure was formed on CoFe2O4@MIL-100(Fe) through hydroxyl substitution with the deprotonated iAs species. Monolayer adsorption of As(V) was observed, while hydrogen bonding led to the multi-layer adsorption of neutral As(III) for its high adsorption capacity. The high efficiency and the excellent pH- and interference-tolerance capacities of CoFe2O4@MIL-100(Fe) allowed effective iAs removal from natural water samples, as validated with batch magnetic separation mode and a portable filtration strategy.

Transparent SiON/Ag/SiON multilayer passivation grown on a flexible polyethersulfone substrate using a continuous roll-to-roll sputtering system

PubMed Central

2012-01-01

We have investigated the characteristics of a silicon oxynitride/silver/silicon oxynitride [SiON/Ag/SiON] multilayer passivation grown using a specially designed roll-to-roll [R2R] sputtering system on a flexible polyethersulfone substrate. Optical, structural, and surface properties of the R2R grown SiON/Ag/SiON multilayer were investigated as a function of the SiON thickness at a constant Ag thickness of 12 nm. The flexible SiON/Ag/SiON multilayer has a high optical transmittance of 87.7% at optimized conditions due to the antireflection and surface plasmon effects in the oxide-metal-oxide structure. The water vapor transmission rate of the SiON/Ag/SiON multilayer is 0.031 g/m2 day at an optimized SiON thickness of 110 nm. This indicates that R2R grown SiON/Ag/SiON is a promising thin-film passivation for flexible organic light-emitting diodes and flexible organic photovoltaics due to its simple and low-temperature process. PMID:22221400

Real-time investigations of structural and optical changes in photochromic Ag/TiO2 nanocomposite thin films under laser irradiation

NASA Astrophysics Data System (ADS)

Babonneau, D.; Diop, D. K.; Simonot, L.; Lamongie, B.; Blanc, N.; Boudet, N.; Vocanson, F.; Destouches, N.

2018-03-01

Photochromic reaction dynamics in silver nanoparticles embedded in mesoporous titanium dioxide thin films is investigated by combining real-time grazing incidence small-angle x-ray scattering (GISAXS) and optical transmission measurements during UV-visible laser exposure cycles. While GISAXS probes changes in the particle size distribution, transmittance measurements are sensitive to spectral changes induced by photo-activated processes. Our results reveal a repeatable photochromic behavior with a good correlation in terms of kinetics between the morphological and optical fluctuations. Visible laser irradiation at 532 nm induces a preferential photo-dissolution of small silver particles, which in turn causes an increase in transmittance near the excitation wavelength. Furthermore, the photo-dissolution process can be significantly accelerated and amplified by associating visible laser with x-ray irradiation. Under UV laser irradiation at 360 nm, the bleaching process can be reverted by photocatalytic reduction with the mesopores in the TiO2 film acting as molds, which have the ability to confine the nanoparticle growth. However, in the irradiation conditions used in the present study, it appears that the photocatalytic growth of silver nanoparticles is slower than the photo-dissolution process, whereas its efficiency gradually degrades throughout the exposures to UV light.

Morphology, microstructure, and magnetic properties of ordered large-pore mesoporous cadmium ferrite thin film spin glasses.

PubMed

Reitz, Christian; Suchomski, Christian; Chakravadhanula, Venkata Sai Kiran; Djerdj, Igor; Jagličić, Zvonko; Brezesinski, Torsten

2013-04-01

Herein, we report the synthesis, microstructure, and magnetic properties of cadmium ferrite (CdFe2O4) thin films with both an ordered cubic network of 18 nm diameter pores and single-phase spinel grains averaging 13 nm in diameter. These mesoporous materials were produced through facile polymer templating of hydrated nitrate salt precursors. Both the morphology and the microstructure, including cation site occupancy and electronic bonding configuration, were analyzed in detail by electron microscopy, grazing incidence small-angle X-ray scattering, Raman and X-ray photoelectron spectroscopy, and N2-physisorption. The obtained data demonstrate that the network of pores is retained up to annealing temperatures as high as 650 °C--the onset of crystallization is at ϑ = (590 ± 10) °C. Furthermore, they show that the polymer-templated samples exhibit a "partially" inverted spinel structure with inversion parameter λ = 0.40 ± 0.02. This differs from microcrystalline CdFe2O4 which shows virtually no inversion. Magnetic susceptibility studies reveal ferrimagnetic spin coupling below 147 K and further point to the likelihood of glassy behavior at low temperature (T(f) ≈ 60 K). In addition, analysis of room temperature magnetization data indicates the presence of sub-10 nm diameter superparamagnetic clusters in an otherwise paramagnetic environment.

Preparation of Three-Dimensional Graphene Foams Using Powder Metallurgy Templates.

PubMed

Sha, Junwei; Gao, Caitian; Lee, Seoung-Ki; Li, Yilun; Zhao, Naiqin; Tour, James M

2016-01-26

A simple and scalable method which combines traditional powder metallurgy and chemical vapor deposition is developed for the synthesis of mesoporous free-standing 3D graphene foams. The powder metallurgy templates for 3D graphene foams (PMT-GFs) consist of particle-like carbon shells which are connected by multilayered graphene that shows high specific surface area (1080 m(2) g(-1)), good crystallization, good electrical conductivity (13.8 S cm(-1)), and a mechanically robust structure. The PMT-GFs did not break under direct flushing with DI water, and they were able to recover after being compressed. These properties indicate promising applications of PMT-GFs for fields requiring 3D carbon frameworks such as in energy-based electrodes and mechanical dampening.

Unsupported thin film beam splitter

NASA Technical Reports Server (NTRS)

Bastien, R. C.; Scheuerman, R. J.

1972-01-01

Multilayer beam splitter system yielding nearly equal broadband infrared reflectance and transmittance in the 5 to 50 micron spectral region has been developed which will significantly reduce size and cost of light path compensating devices in infrared spectral instruments.

Thermal activation in Co/Sb nanoparticle-multilayer thin films

NASA Astrophysics Data System (ADS)

Madden, Michael R.

Multilayer "Co" /"Sb" thin films created via electron-beam physical vapor deposition are known to exhibit thermally activated dynamics. Scanning tunneling microscopy has indicated that the "Co" forms nanoparticles within an "Sb" matrix during deposition and subsequently forms nanowires by way of NP migration within the interstices of the confining layers. The electrical resistance of these systems decays during this irreversible aging process in a manner well-modeled by an Arrhenius law. Presently, this phenomenon is shown to possess some degree of tunability with respect to "Co" layer thickness tCo as well as deposition temperature Tdep , whereby characteristic timescales increase with either parameter. Furthermore, fluctuation timescales and activation energies seem to decrease and increase respectively with increasing t Co. An easily calibrated, one-time-use, time-temperature switch based on such systems lies within the realm of plausibility. The results presented here can be considered to be part of an ongoing development of the concept.

Coloration mechanisms and phylogeny of Morpho butterflies.

PubMed

Giraldo, M A; Yoshioka, S; Liu, C; Stavenga, D G

2016-12-15

Morpho butterflies are universally admired for their iridescent blue coloration, which is due to nanostructured wing scales. We performed a comparative study on the coloration of 16 Morpho species, investigating the morphological, spectral and spatial scattering properties of the differently organized wing scales. In numerous previous studies, the bright blue Morpho coloration has been fully attributed to the multi-layered ridges of the cover scales' upper laminae, but we found that the lower laminae of the cover and ground scales play an important additional role, by acting as optical thin film reflectors. We conclude that Morpho coloration is a subtle combination of overlapping pigmented and/or unpigmented scales, multilayer systems, optical thin films and sometimes undulated scale surfaces. Based on the scales' architecture and their organization, five main groups can be distinguished within the genus Morpho, largely agreeing with the accepted phylogeny. © 2016. Published by The Company of Biologists Ltd.

Thin Film Physical Sensor Instrumentation Research and Development at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.

2006-01-01

A range of thin film sensor technology has been demonstrated enabling measurement of multiple parameters either individually or in sensor arrays including temperature, strain, heat flux, and flow. Multiple techniques exist for refractory thin film fabrication, fabrication and integration on complex surfaces and multilayered thin film insulation. Leveraging expertise in thin films and high temperature materials, investigations for the applications of thin film ceramic sensors has begun. The current challenges of instrumentation technology are to further develop systems packaging and component testing of specialized sensors, further develop instrumentation techniques on complex surfaces, improve sensor durability, and to address needs for extreme temperature applications. The technology research and development ongoing at NASA Glenn for applications to future launch vehicles, space vehicles, and ground systems is outlined.

Superconducting Thin Films for the Enhancement of Superconducting Radio Frequency Accelerator Cavities

NASA Astrophysics Data System (ADS)

Burton, Matthew C.

Bulk niobium (Nb) superconducting radio frequency (SRF) cavities are currently the preferred method for acceleration of charged particles at accelerating facilities around the world. However, bulk Nb cavities have poor thermal conductance, impose material and design restrictions on other components of a particle accelerator, have low reproducibility and are approaching the fundamental material-dependent accelerating field limit of approximately 50MV/m. Since the SRF phenomena occurs at surfaces within a shallow depth of ˜1 microm, a proposed solution to this problem has been to utilize thin film technology to deposit superconducting thin films on the interior of cavities to engineer the active SRF surface in order to achieve cavities with enhanced properties and performance. Two proposed thin film applications for SRF cavities are: 1) Nb thin films coated on bulk cavities made of suitable castable metals (such as copper or aluminum) and 2) multilayer films designed to increase the accelerating gradient and performance of SRF cavities. While Nb thin films on copper (Cu) cavities have been attempted in the past using DC magnetron sputtering (DCMS), such cavities have never performed at the bulk Nb level. However, new energetic condensation techniques for film deposition, such as High Power Impulse Magnetron Sputtering (HiPIMS), offer the opportunity to create suitably thick Nb films with improved density, microstructure and adhesion compared to traditional DCMS. Clearly use of such novel technique requires fundamental studies to assess surface evolution and growth modes during deposition and resulting microstructure and surface morphology and the correlation with RF superconducting properties. Here we present detailed structure-property correlative research studies done on Nb/Cu thin films and NbN- and NbTiN-based multilayers made using HiPIMS and DCMS, respectively.

Tunable thin-film optical filters for hyperspectral microscopy

NASA Astrophysics Data System (ADS)

Favreau, Peter F.; Rich, Thomas C.; Prabhat, Prashant; Leavesley, Silas J.

2013-02-01

Hyperspectral imaging was originally developed for use in remote sensing applications. More recently, it has been applied to biological imaging systems, such as fluorescence microscopes. The ability to distinguish molecules based on spectral differences has been especially advantageous for identifying fluorophores in highly autofluorescent tissues. A key component of hyperspectral imaging systems is wavelength filtering. Each filtering technology used for hyperspectral imaging has corresponding advantages and disadvantages. Recently, a new optical filtering technology has been developed that uses multi-layered thin-film optical filters that can be rotated, with respect to incident light, to control the center wavelength of the pass-band. Compared to the majority of tunable filter technologies, these filters have superior optical performance including greater than 90% transmission, steep spectral edges and high out-of-band blocking. Hence, tunable thin-film optical filters present optical characteristics that may make them well-suited for many biological spectral imaging applications. An array of tunable thin-film filters was implemented on an inverted fluorescence microscope (TE 2000, Nikon Instruments) to cover the full visible wavelength range. Images of a previously published model, GFP-expressing endothelial cells in the lung, were acquired using a charge-coupled device camera (Rolera EM-C2, Q-Imaging). This model sample presents fluorescently-labeled cells in a highly autofluorescent environment. Linear unmixing of hyperspectral images indicates that thin-film tunable filters provide equivalent spectral discrimination to our previous acousto-optic tunable filter-based approach, with increased signal-to-noise characteristics. Hence, tunable multi-layered thin film optical filters may provide greatly improved spectral filtering characteristics and therefore enable wider acceptance of hyperspectral widefield microscopy.

Development of nondestructive testing techniques for plated-through holes in multilayer printed circuit boards

NASA Technical Reports Server (NTRS)

Anthony, P. L.; Mcmurtrey, J. E.

1971-01-01

The development of a nondestructive test with the capability to interrogate plated-through holes as small as 0.51 millimeters inside diameter is discussed. The system can detect defects such as holes, voids, cracks, and thin spots that reduce the current carrying capability of plates-through interconnects by 20 percent or more. Efforts were directed toward the design and fabrication of magnetic circuitry mutual coupling probes and to evaluate the effectiveness of these devices for detecting in multilayer board plated-through holes.

Ag-Pd-Cu alloy inserted transparent indium tin oxide electrodes for organic solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hyo-Joong; Seo, Ki-Won; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr

2014-09-01

The authors report on the characteristics of Ag-Pd-Cu (APC) alloy-inserted indium tin oxide (ITO) films sputtered on a glass substrate at room temperature for application as transparent anodes in organic solar cells (OSCs). The effect of the APC interlayer thickness on the electrical, optical, structural, and morphological properties of the ITO/APC/ITO multilayer were investigated and compared to those of ITO/Ag/ITO multilayer electrodes. At the optimized APC thickness of 8 nm, the ITO/APC/ITO multilayer exhibited a resistivity of 8.55 × 10{sup −5} Ω cm, an optical transmittance of 82.63%, and a figure-of-merit value of 13.54 × 10{sup −3} Ω{sup −1}, comparable to those of the ITO/Ag/ITOmore » multilayer. Unlike the ITO/Ag/ITO multilayer, agglomeration of the metal interlayer was effectively relieved with APC interlayer due to existence of Pd and Cu elements in the thin region of the APC interlayer. The OSCs fabricated on the ITO/APC/ITO multilayer showed higher power conversion efficiency than that of OSCs prepared on the ITO/Ag/ITO multilayer below 10 nm due to the flatness of the APC layer. The improved performance of the OSCs with ITO/APC/ITO multilayer electrodes indicates that the APC alloy interlayer prevents the agglomeration of the Ag-based metal interlayer and can decrease the thickness of the metal interlayer in the oxide-metal-oxide multilayer of high-performance OSCs.« less

Dielectric Properties of BST/(Y 2O 3) x(ZrO 2) 1-x/BST Trilayer Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahoo, Santosh K.; Misra, D.

2011-01-31

Thin films of Ba1-xSrxTiO3 (BST) are being actively investigated for applications in dynamic random access memories (DRAM) because of their properties such as high dielectric constant, low leakage current, and high dielectric breakdown strength. Various approaches have been used to improve the dielectric properties of BST thin films such as doping, graded compositions, and multilayer structures. We have found that inserting a ZrO2 layer in between two BST layers results in a significant reduction in dielectric constant as well as dielectric loss. In this work the effect of Y2O3 doped ZrO2 on the dielectric properties of BST/ZrO2/BST trilayer structure ismore » studied. The structure Ba0.8Sr0.2TiO3/(Y2O3)x(ZrO2)1-x/Ba0.8Sr0.2TiO3 is deposited by a sol-gel process on platinized Si substrate. The composition (x) of the middle layer is varied while keeping the total thickness of the trilayer film constant. The dielectric constant of the multilayer film decreases with the increase of Y2O3 amount in the film whereas there is a slight variation in dielectric loss. In Y2O3 doped multilayer thin films, the dielectric loss is lower in comparison to other films and also there is good frequency stability in the loss in the measured frequency range and hence very suitable for microwave device applications.« less

Electrical current nanogeneration driven by spontaneous nanofluidic oscillations.

PubMed

Gimenez, R; Mercuri, M; Berli, C L A; Bellino, M G

2018-02-15

Exploiting natural phenomena is a central route for providing electricity to sustainably drive wearable electronics. Here we report a nano-scale water-driven energy generator that produces tiny electrical currents from spontaneous wetting-drying oscillations in mesoporous thin films. The system was fabricated with a wormlike mesoporous silica film, which was packed in between Cu and silicon contacts. The nanogenerator runs autonomously when a water droplet is laid over the film close to the Cu electrode, as water infiltration into the film under the electrode produces a direct-current. Wetting-drying cycles, which are spontaneously triggered by water evaporation, are perfectly correlated to the generated electrical current. The autonomous water displacement through the film yields a sustained energy conversion until the droplet reservoir vanishes. This novel water-driven nanogenerator opens new alternatives for versatile, mobile and cost-effective self-powering of nanosystems and nanodevices.

Hierarchically structured photonic crystals for integrated chemical separation and colorimetric detection.

PubMed

Fu, Qianqian; Zhu, Biting; Ge, Jianping

2017-02-16

A SiO 2 colloidal photonic crystal film with a hierarchical porous structure is fabricated to demonstrate an integrated separation and colorimetric detection of chemical species for the first time. This new photonic crystal based thin layer chromatography process requires no dyeing, developing and UV irradiation compared to the traditional TLC. The assembling of mesoporous SiO 2 particles via a supersaturation-induced-precipitation process forms uniform and hierarchical photonic crystals with micron-scale cracks and mesopores, which accelerate the diffusion of developers and intensify the adsorption/desorption between the analytes and silica for efficient separation. Meanwhile, the chemical substances infiltrated to the voids of photonic crystals cause an increase of the refractive index and a large contrast of structural colors towards the unloaded part, so that the sample spots can be directly recognized with the naked eye before and after separation.

Evaluation of strains in bituminous surfaces : stiffness-fatigue investigation.

DOT National Transportation Integrated Search

1973-01-01

The study was designed to determine if strains in Virginia's thin asphaltic pavements were high enough to cause early fatigue failure. Strains were computed with the Chevron multilayer computer program, and also measured on selected highways using el...

Three-dimensional imaging for precise structural control of Si quantum dot networks for all-Si solar cells

NASA Astrophysics Data System (ADS)

Kourkoutis, Lena F.; Hao, Xiaojing; Huang, Shujuan; Puthen-Veettil, Binesh; Conibeer, Gavin; Green, Martin A.; Perez-Wurfl, Ivan

2013-07-01

All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction.All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction. Electronic supplementary information (ESI) available: Electron tomography reconstruction movies. See DOI: 10.1039/c3nr01998e

Characterizing dielectric tensors of anisotropic materials from a single measurement

NASA Astrophysics Data System (ADS)

Smith, Paula Kay

Ellipsometry techniques look at changes in polarization states to measure optical properties of thin film materials. A beam reflected from a substrate measures the real and imaginary parts of the index of the material represented as n and k, respectively. Measuring the substrate at several angles gives additional information that can be used to measure multilayer thin film stacks. However, the outstanding problem in standard ellipsometry is that it uses a limited number of incident polarization states (s and p). This limits the technique to isotropic materials. The technique discussed in this paper extends the standard process to measure anisotropic materials by using a larger set of incident polarization states. By using a polarimeter to generate several incident polarization states and measure the polarization properties of the sample, ellipsometry can be performed on biaxial materials. Use of an optimization algorithm in conjunction with biaxial ellipsometry can more accurately determine the dielectric tensor of individual layers in multilayer structures. Biaxial ellipsometry is a technique that measures the dielectric tensors of a biaxial substrate, single-layer thin film, or multi-layer structure. The dielectric tensor of a biaxial material consists of the real and imaginary parts of the three orthogonal principal indices (n x + ikx, ny +iky and nz + i kz) as well as three Euler angles (alpha, beta and gamma) to describe its orientation. The method utilized in this work measures an angle-of-incidence Mueller matrix from a Mueller matrix imaging polarimeter equipped with a pair of microscope objectives that have low polarization properties. To accurately determine the dielectric tensors for multilayer samples, the angle-of-incidence Mueller matrix images are collected for multiple wavelengths. This is done in either a transmission mode or a reflection mode, each incorporates an appropriate dispersion model. Given approximate a priori knowledge of the dielectric tensor and film thickness, a Jones reflectivity matrix is calculated by solving Maxwell's equations at each surface. Converting the Jones matrix into a Mueller matrix provides a starting point for optimization. An optimization algorithm then finds the best fit dielectric tensor based on the measured angle-of-incidence Mueller matrix image. This process can be applied to polarizing materials, birefringent crystals and the multilayer structures of liquid crystal displays. In particular, the need for such accuracy in liquid crystal displays is growing as their applications in industry evolve.

Thin film multilayer filters for solar EUV telescopes.

PubMed

Chkhalo, N I; Drozdov, M N; Kluenkov, E B; Kuzin, S V; Lopatin, A Ya; Luchin, V I; Salashchenko, N N; Tsybin, N N; Zuev, S Yu

2016-06-10

Al, with a passband in the wavelength range of 17-60 nm, and Zr, with a passband in the wavelength range of 6.5-17 nm, thin films on a support grid or support membrane are frequently used as UV, visible, and near-IR blocking filters in solar observatories. Although they possess acceptable optical performance, these filters also have some shortcomings such as low mechanical strength and low resistance to oxidation. These shortcomings hinder meeting the requirements for filters of future telescopes. We propose multilayer thin film filters on the basis of Al, Zr, and other materials with improved characteristics. It was demonstrated that stretched multilayer films on a support grid with a mesh size up to 5 mm can withstand vibration loads occurring during spacecraft launch. A large mesh size is preferable for filters of high-resolution solar telescopes, since it allows image distortion caused by light diffraction on the support grid to be avoided. We have investigated the thermal stability of Al/Si and Zr/Si multilayers assuming their possible application as filters in the Intergelioprobe project, in which the observation of coronal plasma will take place close to the Sun. Zr/Si films show high thermal stability and may be used as blocking filters in the wavelength range of 12.5-17 nm. Al/Si films show lower thermal stability: a significant decrease in the film's transmission in the EUV spectral range and an increase in the visible spectrum have been observed. We suppose that the low thermal stability of Al/Si films restricts their application in the Intergelioprobe project. Thus, there is a lack of filters for the wavelength range of λ>17  nm. Be/Si and Cr/Si filters have been proposed for the wavelength range near 30.4 nm. Although these filters have lower transparency than Al/Si, they are superior in thermal stability. Multilayer Sc/Al filters with relatively high transmission at a wavelength of 58.4 nm (HeI line) and simultaneously sufficient rejection in the wavelength range near 30.4 nm (HeII line) have been fabricated. They are planned to be used in the project KORTES, whose telescopes will have an EUV channel at 58.4 nm.

Detecting Water Bodies in LANDSAT8 Oli Image Using Deep Learning

NASA Astrophysics Data System (ADS)

Jiang, W.; He, G.; Long, T.; Ni, Y.

2018-04-01

Water body identifying is critical to climate change, water resources, ecosystem service and hydrological cycle. Multi-layer perceptron(MLP) is the popular and classic method under deep learning framework to detect target and classify image. Therefore, this study adopts this method to identify the water body of Landsat8. To compare the performance of classification, the maximum likelihood and water index are employed for each study area. The classification results are evaluated from accuracy indices and local comparison. Evaluation result shows that multi-layer perceptron(MLP) can achieve better performance than the other two methods. Moreover, the thin water also can be clearly identified by the multi-layer perceptron. The proposed method has the application potential in mapping global scale surface water with multi-source medium-high resolution satellite data.

Characterization of casein and poly-l-arginine multilayer films

NASA Astrophysics Data System (ADS)

Szyk-Warszyńska, Lilianna; Kilan, Katarzyna; Socha, Robert P.

2014-06-01

Thin films containing casein appear to be a promising material for coatings used in the medical area to promote biomineralization. alfa- and beta-casein and poly-L-arginine multilayer films were formed by the layer-by layer technique and their thickness and mass were analyzed by ellipsometry and quartz crystal microbalance with dissipation monitoring (QCM-D). We investigated the effect of the type of casein used for the film formation and of the polyethyleneimine anchoring layer on the thickness and mass of adsorbed films. The analysis of the mass of films during their post-treatment with the solutions of various ionic strength and pH provided the information concerning films stability, while the XPS elemental analysis confirmed binding of calcium ions by the casein embedded in the multilayers.

New Insight into Nuclear Reactions in Solids

NASA Astrophysics Data System (ADS)

Miley, George H.

2003-04-01

Earlier work by the author disclosed evidence for nuclear transmutations in multi-layer thin-film Ni/Pd electrodes loaded to a high ratio of hydrogen/film metal using an electrolytic technique [1]. Non-natural isotopes abundances were found for select products. A distinctive characteristic of this and similar experiments by others is a product yield curve vs. mass with four high yield peaks distributed between low and high masses. Attempts to explain this observation have evolved around the original swimming electron layer (SEL) theory [2]. In addition, CR-39 track detector measurements have revealed low-level emission of 1.6 MeV protons and 16 MeV alpha particles from the front face of the thin film electrodes during runs [3]. Most recently Mitsubishi Corp. researchers have reported a real-time transmutation measurement using built-in XPS diagnostics where a surface layer of Sr-88 was transmuted into Mo-96 over a 200 hour run period during the diffusion of deuterium through a multi-layer thin-film Pd/CaO substrate [4]. Likewise in a companion experiment, Cs-133 was transmuted into Pr-141. These products exhibit a large deviation from natural isotopic abundance, and the characteristic signature is a mass change of 8 and charge change of 4. These various phenomena along with a preliminary theory involving SEL and orbital mixing will be presented. The objective is to provide a unified understanding of both types of experiments presented in Refs. 1 and 3. [1] G.H. Miley and J. A. Patterson, "Nuclear Transmutations in Thin-Film Nickel Coatings Undergoing Electrolysis," J. New Energy, 1, 3, 5-30 (1996). [2] H. Hora, et al., "Screening in Cold Fusion Derived from D D Reactions," Physics Ltrs. A, 175, 138-143, (1993). [3] A. Lipson, et al., "In-situ long - range alpha particles and X-ray detection in Pd thin film-cathodes during electrolysis in, Li2SO4/H2O, Bult. APS, 47, 1,Pt. II, 1219, Indianapolis, (2002). [4] Y. Iwamura, T. Itoh, et al., "Low energy nuclear reaction induced by D gas permeation through multilayer film," Japanese J. Physics, 41, pt. 1, 7A, 4642, (2002).

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

NASA Astrophysics Data System (ADS)

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

2012-09-01

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.

Nonlinear multilayers as optical limiters

NASA Astrophysics Data System (ADS)

Turner-Valle, Jennifer Anne

1998-10-01

In this work we present a non-iterative technique for computing the steady-state optical properties of nonlinear multilayers and we examine nonlinear multilayer designs for optical limiters. Optical limiters are filters with intensity-dependent transmission designed to curtail the transmission of incident light above a threshold irradiance value in order to protect optical sensors from damage due to intense light. Thin film multilayers composed of nonlinear materials exhibiting an intensity-dependent refractive index are used as the basis for optical limiter designs in order to enhance the nonlinear filter response by magnifying the electric field in the nonlinear materials through interference effects. The nonlinear multilayer designs considered in this work are based on linear optical interference filter designs which are selected for their spectral properties and electric field distributions. Quarter wave stacks and cavity filters are examined for their suitability as sensor protectors and their manufacturability. The underlying non-iterative technique used to calculate the optical response of these filters derives from recognizing that the multi-valued calculation of output irradiance as a function of incident irradiance may be turned into a single-valued calculation of incident irradiance as a function of output irradiance. Finally, the benefits and drawbacks of using nonlinear multilayer for optical limiting are examined and future research directions are proposed.

Effects of interfaces on the thermal conductivity in Si/Si0.75Ge0.25 multilayer with varying Au layers

NASA Astrophysics Data System (ADS)

Hu, Yangsen; Wu, Zhenghua; Ye, Fengjie; Hu, Zhiyu

2018-02-01

The manoeuvre of thermal transport property across multilayer films with inserted metal layers through controlling the metal-nonmetal interfaces is of fundamental interest. In this work, amorphous Si/Si0.75Ge0.25 multilayer films inserted with varying Au layers were fabricated by magnetron sputtering. The structure and sharp interface of multilayers films were characterized by low angle x-ray diffraction (LAXRD), grazing incidence small angle x-ray scattering (GISAXS) and scanning electron microscopy (SEM). A differential 3ω method was applied to measure the effective thermal conductivity. The measurements show that thermal conductivity has changed as varying Au layers. Thermal conductivity increased from 0.94 to 1.31 Wm-1K-1 while Si0.75Ge0.25 layer was replaced by different Au layers, which was attributed to the strong electron-phonon coupling and interface thermal resistance in a metal-nonmetal multilayered system. Theoretical calculation combined with experimental results indicate that the thermal conductivity of the multilayer film could be facilely controlled by introducing different number of nanoconstructed metal-nonmetal interfaces, which provide a more insightful understanding of the thermal transport manipulation mechanism of the thin film system with inserting metal layers.

Multilayered Electromagnetic Interference Shielding Structures for Suppressing Magnetic Field Coupling

NASA Astrophysics Data System (ADS)

Watanabe, Atom O.; Raj, Pulugurtha Markondeya; Wong, Denny; Mullapudi, Ravi; Tummala, Rao

2018-05-01

Control of electromagnetic interference (EMI) represents a major challenge for emerging consumer electronics, the Internet of Things, automotive electronics, and wireless communication systems. This paper discusses innovative EMI shielding materials and structures that offer higher shielding effectiveness compared with copper. To create high shielding effectiveness in the frequency range of 1 MHz to 100 MHz, multilayered shielding topologies with electrically conductive and nanomagnetic materials were modeled, designed, fabricated, and characterized. In addition, suppression of out-of-plane and in-plane magnetic-field coupling noise with these structures is compared with that of traditional single-layer copper or nickel-iron films. Compared with single-layered copper shields, multilayered structures consisting of copper, nickel-iron, and titanium showed a 3.9 times increase in shielding effectiveness in suppressing out-of-plane or vertically coupled noise and 1.3 times increase in lateral coupling. The superiority of multilayered thin-film shields over conventional shielding enables greater design flexibility, higher shielding effectiveness, and further miniaturization of emerging radiofrequency (RF) and power modules.

Thin film photovoltaic device

DOEpatents

Catalano, A.W.; Bhushan, M.

1982-08-03

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids. 5 figs.

Deodorisation effect of diamond-like carbon/titanium dioxide multilayer thin films deposited onto polypropylene

NASA Astrophysics Data System (ADS)

Ozeki, K.; Hirakuri, K. K.; Masuzawa, T.

2011-04-01

Many types of plastic containers have been used for the storage of food. In the present study, diamond-like carbon (DLC)/titanium oxide (TiO2) multilayer thin films were deposited on polypropylene (PP) to prevent flavour retention and to remove flavour in plastic containers. For the flavour removal test, two types of multilayer films were prepared, DLC/TiO2 films and DLC/TiO2/DLC films. The residual gas concentration of acetaldehyde, ethylene, and turmeric compounds in bottle including the DLC/TiO2-coated and the DLC/TiO2/DLC-coated PP plates were measured after UV radiation, and the amount of adsorbed compounds to the plates was determined. The percentages of residual gas for acetaldehyde, ethylene, and turmeric with the DLC/TiO2 coated plates were 0.8%, 65.2% and 75.0% after 40 h of UV radiation, respectively. For the DLC/TiO2/DLC film, the percentages of residual gas for acetaldehyde, ethylene and turmeric decreased to 34.9%, 76.0% and 85.3% after 40 h of UV radiation, respectively. The DLC/TiO2/DLC film had a photocatalytic effect even though the TiO2 film was covered with the DLC film.

Thin Aerogel as a Spacer in Multilayer Insulation

NASA Technical Reports Server (NTRS)

Moroz, Nancy

2015-01-01

Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on real-world tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

Thin Aerogel as a Spacer in Multilayer Insulation

NASA Technical Reports Server (NTRS)

Moroz, Nancy

2015-01-01

Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on rea-lworld tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

Metal oxide multilayer hard mask system for 3D nanofabrication

NASA Astrophysics Data System (ADS)

Han, Zhongmei; Salmi, Emma; Vehkamäki, Marko; Leskelä, Markku; Ritala, Mikko

2018-02-01

We demonstrate the preparation and exploitation of multilayer metal oxide hard masks for lithography and 3D nanofabrication. Atomic layer deposition (ALD) and focused ion beam (FIB) technologies are applied for mask deposition and mask patterning, respectively. A combination of ALD and FIB was used and a patterning procedure was developed to avoid the ion beam defects commonly met when using FIB alone for microfabrication. ALD grown Al2O3/Ta2O5/Al2O3 thin film stacks were FIB milled with 30 keV gallium ions and chemically etched in 5% tetramethylammonium hydroxide at 50 °C. With metal evaporation, multilayers consisting of amorphous oxides Al2O3 and Ta2O5 can be tailored for use in 2D lift-off processing, in preparation of embedded sub-100 nm metal lines and for multilevel electrical contacts. Good pattern transfer was achieved by lift-off process from the 2D hard mask for micro- and nano-scaled fabrication. As a demonstration of the applicability of this method to 3D structures, self-supporting 3D Ta2O5 masks were made from a film stack on gold particles. Finally, thin film resistors were fabricated by utilizing controlled stiction of suspended Ta2O5 structures.

Three-Dimensional Microphase Separation and Synergistic Permeability in Stacked Lipid–Polymer Hybrid Membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Minjee; Lee, Byeongdu; Leal, Cecilia

Here, we present new structures of soft-material thin films that augment the functionality of substrate-mediated delivery systems. A hybrid material composed of phospholipids and block copolymers adopts a multilayered membrane structure supported on a solid surface. The hybrid films comprise intentional intramembrane heterogeneities that register across multilayers. These stacked domains convey unprecedented enhancement and control of permeability of solutes across micrometer-thick films. Using grazing incidence X-ray scattering, phase contrast atomic force microscopy, and confocal microscopy, we observed that in each lamella, lipid and polymers partition unevenly within the membrane plane segregating into lipid- or polymer-rich domains. Interestingly, we found evidencemore » that like-domains align in registry across multilayers, thereby making phase separation three-dimensional. Phase boundaries exist over extended length scales to compensate the height mismatch between lipid and polymer molecules. We show that microphase separation in hybrid films can be exploited to augment the capability of drug-eluting substrates. Lipid–polymer hybrid films loaded with paclitaxel show synergistic permeability of drug compared to single-component counterparts. We present a thorough structural study of stacked lipid–polymer hybrid membranes and propose that the presence of registered domains and domain boundaries impart enhanced drug release functionality. This work offers new perspectives in designing thin films for controlled delivery applications« less

Deformation sensor based on polymer-supported discontinuous graphene multi-layer coatings

NASA Astrophysics Data System (ADS)

Carotenuto, G.; Schiavo, L.; Romeo, V.; Nicolais, L.

2014-05-01

Graphene can be conveniently used in the modification of polymer surfaces. Graphene macromolecules are perfectly transparent to the visible light and electrically conductive, consequently these two properties can be simultaneously provided to polymeric substrates by surface coating with thin graphene layers. In addition, such coating process provides the substrates of: water-repellence, higher surface hardness, low-friction, self-lubrication, gas-barrier properties, and many other functionalities. Polyolefins have a non-polar nature and therefore graphene strongly sticks on their surface. Nano-crystalline graphite can be used as graphene precursor in some chemical processes (e.g., graphite oxide synthesis by the Hummer method), in addition it can be directly applied to the surface of a polyolefin substrate (e.g., polyethylene) to cover it by a thin graphene multilayer. In particular, the nano-crystalline graphite perfectly exfoliate under the application of a combination of shear and friction forces and the produced graphene single-layers perfectly spread and adhere on the polyethylene substrate surface. Such polymeric materials can be used as ITO (indium-tin oxide) substitute and in the fabrication of different electronic devices. Here the fabrication of transparent resistive deformation sensors based on low-density polyethylene films coated by graphene multilayers is described. Such devices are very sensible and show a high reversible and reproducible behavior.

A soft gamma-ray concentrator using thin-film multilayer structures

NASA Astrophysics Data System (ADS)

Bloser, Peter F.; Aliotta, Paul H.; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Shirazi, Farzane; Tsavalas, John G.; Wong, Emily N.; Kippen, R. Marc

2015-09-01

We have begun to investigate the use of thin-film, multilayer structures to form optics capable of concentrating soft gamma rays with energies greater than 100 keV, beyond the reach of current grazing-incidence hard X-ray mirrors. Alternating layers of low- and high-density materials (e.g., polymers and metals) will channel soft gamma-ray photons via total external reflection. A suitable arrangement of bent structures will then concentrate the incident radiation to a point. Gamma-ray optics made in this way offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments. Building on initial investigations at Los Alamos National Laboratory, we are investigating whether it is possible to grow such flexible multi-layer structures with the required thicknesses and smoothness using magnetron sputter and pulsed laser deposition techniques. We present the initial results of tests aimed at fabricating such structures by combining magnetron sputtering with either spin coating or pulsed laser deposition, and demonstrating gamma-ray channeling of 122 keV photons in the laboratory. If successful, this technology offers the potential for transformational increases in sensitivity while dramatically improving the system-level performance of future high-energy astronomy missions through reduced mass and complexity.

Three-Dimensional Microphase Separation and Synergistic Permeability in Stacked Lipid–Polymer Hybrid Membranes

DOE PAGES

Kang, Minjee; Lee, Byeongdu; Leal, Cecilia

2017-10-20

Here, we present new structures of soft-material thin films that augment the functionality of substrate-mediated delivery systems. A hybrid material composed of phospholipids and block copolymers adopts a multilayered membrane structure supported on a solid surface. The hybrid films comprise intentional intramembrane heterogeneities that register across multilayers. These stacked domains convey unprecedented enhancement and control of permeability of solutes across micrometer-thick films. Using grazing incidence X-ray scattering, phase contrast atomic force microscopy, and confocal microscopy, we observed that in each lamella, lipid and polymers partition unevenly within the membrane plane segregating into lipid- or polymer-rich domains. Interestingly, we found evidencemore » that like-domains align in registry across multilayers, thereby making phase separation three-dimensional. Phase boundaries exist over extended length scales to compensate the height mismatch between lipid and polymer molecules. We show that microphase separation in hybrid films can be exploited to augment the capability of drug-eluting substrates. Lipid–polymer hybrid films loaded with paclitaxel show synergistic permeability of drug compared to single-component counterparts. We present a thorough structural study of stacked lipid–polymer hybrid membranes and propose that the presence of registered domains and domain boundaries impart enhanced drug release functionality. This work offers new perspectives in designing thin films for controlled delivery applications« less

Simulation and Optimization of Soft Gamma-Ray Concentrator Using Thin Film Multilayer Structures

NASA Astrophysics Data System (ADS)

Shirazi, Farzane; Bloser, Peter F.; Aliotta, Paul H.; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Tsavalas, John G.; Wong, Emily N.; Kippen, R. Marc

2016-04-01

We are reporting the investigation result of channeling and concentrating soft gamma rays (above 100 keV) using multilayer thin films of alternating low and high-density materials. This will enable future telescopes for higher energies with same mission parameters already proven by NuSTAR. Base on initial investigations at Los Alamos National Laboratory (LANL) we are investigating of producing these multilayers with the required thicknesses and smoothness using magnetron sputter (MS) and pulsed laser deposition (PLD) techniques. A suitable arrangement of bent multilayer structures of alternating low and high-density materials will channel soft gamma-ray photons via total external reflection and then concentrate the incident radiation to a point. The high-energy astrophysics group at the UNH Space Science Center (SSC) is testing these structures for their ability to channel 122 keV gamma rays in the laboratory. In addition of experimental works, we have been working on gamma ray tracing model of the concentrator by IDL, making use of optical properties calculated by the IMD software. This modeling allows us to calculate efficiency and focal length for different energy bands and materials and compare them with experimental result. Also we will combine concentrator modeling result and detector simulation by Geant4 to archive a complete package of gamma-ray telescope simulation. If successful, this technology will offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments and providing greatly increased sensitivity for modest cost and complexity.

Mesoporous Silica Gel-Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler.

PubMed

Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y; Huo, Fengwei

2015-11-23

The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4-30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores.

Mesoporous Silica Gel–Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler

PubMed Central

Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y.; Huo, Fengwei

2015-01-01

The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4–30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores. PMID:26592565

Ion Beam Analysis of Iridium-Based TES for Microcalorimeter Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomes, M. Ribeiro; Galeazzi, M.; Bogorin, D.

2009-12-16

The physical properties of thin multilayer structures are deeply related to the crystalline quality and stoichiometry of the films. The interface roughness/mixing require a detailed study to determine its influence on the growth processes and surface topography. This is an important aspect when we have lattice mismatch between the superconducting thin-films and the substrates, and a high reliability/reproducibility is required as for large array microcalorimeter applications, as in the case of the MARE experiment, designed to measure the mass of the neutrino with sub-eV sensitivity by measuring the beta decay of {sup 187}Re with cryogenic microcalorimeters. Ion beam analysis techniquesmore » are ideal to determine the thickness and concentration profiles of the chemical species in ultra-thin films. Here we present the results on the Ir-based superconducting films deposited on Si-substrates based on systematic investigations of the concentration depth profiles of the multilayer structure using 2.0 MeV {sup 4}He{sup +} ions for high resolution Rutherford Backscattering Spectrometry combined with X-Ray Reflectrometry to evaluate the interface/roughness mixing and the crystalline quality in the TES prototypes.« less

Thin film characterization by laser interferometry combined with SIMS

NASA Astrophysics Data System (ADS)

Kempf, J.; Nonnenmacher, M.; Wagner, H. H.

1988-10-01

Thin film properties of technologically important materials (Si, GaAs, SiO2, WSix) have been measured by using a novel technique that combines secondary ion mass spectrometry (SIMS) and laser interferometry. The simultaneous measurement of optical phase and reflectance as well as SIMS species during ion sputtering yielded optical constants, sputtering rates and composition of thin films with high depth resolution. A model based on the principle of multiple reflection within a multilayer structure, which considered also transformation of the film composition in depth and time during sputtering, was fitted to the reflectance and phase data. This model was applied to reveal the transformation of silicon by sputtering with O{2/+} ions. Special attention was paid to the preequilibrium phase of the sputter process (amorphization, oxidation, and volume expansion). To demonstrate the analytical potential of our method the multilayer system WSix/poly-Si/SiO2/Si was investigated. The physical parameters and the stoichiometry of tungsten suicide were determined for annealed as well as deposited films. A highly sensitive technique that makes use of a Fabry-Perot etalon integrated with a Michelson type interferometer is proposed. This two-stage interferometer has the potential to profile a sample surface with subangstroem resolution.

Nanostructured multilayer thin films of multiwalled carbon nanotubes/gold nanoparticles/glutathione for the electrochemical detection of dopamine

NASA Astrophysics Data System (ADS)

Detsri, Ekarat; Rujipornsakul, Sirilak; Treetasayoot, Tanapong; Siriwattanamethanon, Pawarit

2016-10-01

In the present study, multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (AuNPs), and glutathione (GSH) were used to fabricate multilayer nanoscale thin films. The composite thin films were fabricated by layer-by-layer technique as the films were constructed by the alternate deposition of cationic and anionic polyelectrolytes. The MWCNTs were modified via a noncovalent surface modification method using poly(diallydimethylammonium chloride) to form a cationic polyelectrolyte. An anionic polyelectrolyte was prepared by the chemical reduction of HAuCl4 using sodium citrate as both the stabilizing and reducing agent to form anionic AuNPs. GSH was used as an electrocatalyst toward the electro-oxidation of dopamine. The constructed composite electrode exhibits excellent electrocatalytic activity toward dopamine with a short response time and a wide linear range from 1 to 100 μmol/L. The limits of detection and quantitation of dopamine are (0.316 ± 0.081) μmol/L and (1.054 ± 0.081) μmol/L, respectively. The method is satisfactorily applied for the determination of dopamine in plasma and urine samples to obtain the recovery in the range from 97.90% to 105.00%.

Tracing the 4000 year history of organic thin films: From monolayers on liquids to multilayers on solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greene, J. E.; Linköping University, 581 83 Linköping; National Taiwan University of Science and Technology, Taipei 10607, Taiwan

The recorded history of organic monolayer and multilayer thin films spans approximately 4000 years. Fatty-acid-based monolayers were deposited on water by the ancients for applications ranging from fortune telling in King Hammurabi's time (∼1800 BC, Mesopotamia) to stilling choppy waters for sailors and divers as reported by the Roman philosopher Pliny the Elder in ∼78 AD, and then much later (1774) by the peripatetic American statesman and natural philosopher Benjamin Franklin, to Japanese “floating-ink” art (suminagashi) developed ∼1000 years ago. The modern science of organic monolayers began in the late-1800s/early-1900s with experiments by Lord Rayleigh and the important development bymore » Agnes Pockels, followed two decades later by Irving Langmuir, of the tools and technology to measure the surface tension of liquids, the surface pressure of organic monolayers deposited on water, interfacial properties, molecular conformation of the organic layers, and phase transitions which occur upon compressing the monolayers. In 1935, Katherine Blodgett published a landmark paper showing that multilayers can be synthesized on solid substrates, with controlled thickness and composition, using an apparatus now known as the Langmuir-Blodgett (L-B) trough. A disadvantage of LB films for some applications is that they form weak physisorbed bonds to the substrate. In 1946, Bigelow, Pickett, and Zisman demonstrated, in another seminal paper, the growth of organic self-assembled monolayers (SAMs) via spontaneous adsorption from solution, rather than from the water/air interface, onto SiO{sub 2} and metal substrates. SAMs are close-packed two-dimensional organic crystals which exhibit strong covalent bonding to the substrate. The first multicomponent adsorbed monolayers and multilayer SAMs were produced in the early 1980s. Langmuir monolayers, L-B multilayers, and self-assembled mono- and multilayers have found an extraordinarily broad range of applications including controlled wetting, adhesion, electrochemistry, biocompatibility, molecular recognition, biosensing, cell biology, non-linear optics, molecular electronics, solar cells, read/write/erase memory, and magnetism.« less

Determination and analysis of non-linear index profiles in electron-beam-deposited MgOAl2O3ZrO2 ternary composite thin-film optical coatings

NASA Astrophysics Data System (ADS)

Sahoo, N. K.; Thakur, S.; Senthilkumar, M.; Das, N. C.

2005-02-01

Thickness-dependent index non-linearity in thin films has been a thought provoking as well as intriguing topic in the field of optical coatings. The characterization and analysis of such inhomogeneous index profiles pose several degrees of challenges to thin-film researchers depending upon the availability of relevant experimental and process-monitoring-related information. In the present work, a variety of novel experimental non-linear index profiles have been observed in thin films of MgOAl2O3ZrO2 ternary composites in solid solution under various electron-beam deposition parameters. Analysis and derivation of these non-linear spectral index profiles have been carried out by an inverse-synthesis approach using a real-time optical monitoring signal and post-deposition transmittance and reflection spectra. Most of the non-linear index functions are observed to fit polynomial equations of order seven or eight very well. In this paper, the application of such a non-linear index function has also been demonstrated in designing electric-field-optimized high-damage-threshold multilayer coatings such as normal- and oblique-incidence edge filters and a broadband beam splitter for p-polarized light. Such designs can also advantageously maintain the microstructural stability of the multilayer structure due to the low stress factor of the non-linear ternary composite layers.

X-ray optics made from thin plastic foils

NASA Astrophysics Data System (ADS)

Schnopper, H. W.; Barbera, M.; Ingram, R.; Silver, E.; Romaine, S.; Bandler, S.; Murray, S.; Christensen, F. E.; Hussain, A.; Collura, A.

2000-10-01

New design concepts and materials can be used to produce lightweight, thin foil approximations, to Wolter I and other X-ray optics. Structures are designed around a central hub and spacers that connect two (or three) spoked wheels. Figure defining, thin pins span the distance between the wheels. Thin, metal coated or multilayered, plastic foils can be formed into full cones, cylinders or spirals for X-ray telescopes or lenses. High resolution X-ray scattering data were obtained for single foils at Cu K (8 KeV). Multi-energy (0.28 - 8 KeV) data were obtained with a multichannel plate imager in a 17 m beam line with a point-to-point focusing, cylindrical X-ray lens with 14 shells. The largest shell has a diameter of 175 mm and a length of 100 mm. Typical images have a FWHM of 20 arcsec. The results indicate that a 60 cm diameter, 4.65 m focal length X-ray telescope can have an HPD of considerably less than 2 arcmin. This research is supported, in part by NASA Grant NAG5-5268, ONR Grant N00014-95-1-1248, and by institutional funding from the Smithsonian Astrophysical Observatory. The SAO multilayer facility receives support from NASA Grant NAG5-5095. This work made use of the MRSEC Shared Experimental Facilities at MIT supported by NSF Grant DMR94-00334.

Electrospun fibrous thin film microextraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human plasma.

PubMed

Chen, Di; Hu, Yu-Ning; Hussain, Dilshad; Zhu, Gang-Tian; Huang, Yun-Qing; Feng, Yu-Qi

2016-05-15

Appropriate sample preparations prior to analysis can significantly enhance the sensitivity of ambient ionization techniques, especially during the enrichment or purification of analytes in the presence of complex biological matrix. Here in, we developed a rapid analysis method by the combination of thin film microextraction (TFME) and desorption corona beam ionization (DCBI) for the determination of antidepressants in human plasma. Thin films used for extraction consisted of sub-micron sized highly ordered mesoporous silica-carbon composite fibers (OMSCFs), simply prepared by electrospinning and subsequent carbonization. Typically, OMSCFs thin film was immersed into the diluted plasma for extraction of target analytes and then directly subjected to the DCBI-MS for detection. Size-exclusion effect of mesopores contributed to avoid of the protein precipitation step prior to extraction. Mass transfer was benefited from high surface-to-volume ratio which is attributed to macroporous network and ordered mesostructures. Moreover, the OMSCFs provided mixed-mode hydrophobic/ion-exchange interactions towards target analytes. Thus, the detection sensitivity was greatly improved due to effective enrichment of the target analytes and elimination of matrix interferences. After optimization of several parameters related to extraction performance, the proposed method was eventually applied for the determination of three antidepressants in human plasma. The calibration curves were plotted in the range of 5-1000 ng/mL with acceptable linearity (R(2) >0.983). The limits of detection (S/N=3) of three antidepressants were in ranges of 0.3-1 ng/mL. Reproducibility was achieved with RSD less than 17.6% and the relative recoveries were in ranges of 83.6-116.9%. Taken together, TFME-DCBI-MS method offers a powerful capacity for rapid analysis to achieve much-improved sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

A Magnetron Sputter Deposition System for the Development of Multilayer X-Ray Optics

NASA Technical Reports Server (NTRS)

Broadway, David; Ramsey, Brian; Gubarev, Mikhail

2014-01-01

The proposal objective is to establish the capability to deposit multilayer structures for x-ray, neutron, and EUV optic applications through the development of a magnetron sputtering deposition system. A specific goal of this endeavor is to combine multilayer deposition technology with the replication process in order to enhance the MSFC's position as a world leader in the design of innovative X-ray instrumentation through the development of full shell replicated multilayer optics. The development of multilayer structures is absolutely necessary in order to advance the field of X-ray astronomy by pushing the limit for observing the universe to ever increasing photon energies (i. e. up to 200 keV or higher); well beyond Chandra (approx. 10 keV) and NuStar's (approx. 75 keV) capability. The addition of multilayer technology would significantly enhance the X-ray optics capability at MSFC and allow NASA to maintain its world leadership position in the development, fabrication and design of innovative X-ray instrumentation which would be the first of its kind by combining multilayer technology with the mirror replication process. This marriage of these technologies would allow astronomers to see the universe in a new light by pushing to higher energies that are out of reach with today's instruments.To this aim, a magnetron vacum sputter deposition system for the deposition of novel multilayer thin film X-ray optics is proposed. A significant secondary use of the vacuum deposition system includes the capability to fabricate multilayers for applications in the field of EUV optics for solar physics, neutron optics, and X-ray optics for a broad range of applications including medical imaging.

A Magnetron Sputter Deposition System for the Development of X-Ray Multilayer Optics

NASA Technical Reports Server (NTRS)

Broadway, David

2015-01-01

The project objective is to establish the capability to deposit multilayer structures for x-ray, neutron, and extreme ultraviolet (EUV) optic applications through the development of a magnetron sputtering deposition system. A specific goal of this endeavor is to combine multilayer deposition technology with the replication process in order to enhance NASA Marshall Space Flight Center's (MSFC's) position as a world leader in the design of innovative x-ray instrumentation through the development of full shell replicated multilayer optics. The development of multilayer structures are absolutely necessary in order to advance the field of x-ray astronomy by pushing the limit for observing the universe to ever-increasing photon energies (i.e., up to 200 keV or higher), well beyond Chandra's (approx.10 keV) and NuStar's (approx.75 keV) capability. The addition of multilayer technology would significantly enhance the x-ray optics capability at MSFC and allow NASA to maintain its world leadership position in the development, fabrication, and design of innovative x-ray instrumentation, which would be the first of its kind by combining multilayer technology with the mirror replication process. This marriage of these technologies would allow astronomers to see the universe in a new light by pushing to higher energies that are out of reach with today's instruments. To this aim, a magnetron vacuum sputter deposition system for the deposition of novel multilayer thin film x-ray optics is proposed. A significant secondary use of the vacuum deposition system includes the capability to fabricate multilayers for applications in the field of EUV optics for solar physics, neutron optics, and x-ray optics for a broad range of applications including medical imaging.

Triple-wavelength, narrowband Mg/SiC multilayers with corrosion barriers and high peak reflectance in the 25-80 nm wavelength region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernández-Perea, Mónica; Soufli, Regina; Robinson, Jeff C.

2012-01-01

We have developed new, corrosion-resistant Mg/SiC multilayer coatings which can be used to efficiently and simultaneously reflect extreme ultraviolet (EUV) radiation in single or multiple narrow bands centered at wavelengths in the spectral region from 25 to 80 nm. Corrosion mitigation is achieved through the use of partially amorphous Al-Mg thin layers. Three different multilayer design concepts were developed and deposited by magnetron sputtering and the reflectance was measured at near-normal incidence in a broad spectral range. Unprotected Mg/SiC multilayers were also deposited and measured for comparison. They were shown to efficiently reflect radiation at a wavelength of 76.9 nmmore » with a peak reflectance of 40.6% at near-normal incidence, the highest experimental reflectance reported at this wavelength for a narrowband coating. The demonstration of multilayer coatings with corrosion resistance and multiplewavelength EUV performance is of great interest in the development of mirrors for space-borne solar physics telescopes and other applications requiring long-lasting coatings with narrowband response in multiple emission lines across the EUV range.« less

Critical aspects in the production of periodically ordered mesoporous titania thin films

NASA Astrophysics Data System (ADS)

Soler-Illia, Galo J. A. A.; Angelomé, Paula C.; Fuertes, M. Cecilia; Grosso, David; Boissiere, Cedric

2012-03-01

Periodically ordered mesoporous titania thin films (MTTF) present a high surface area, controlled porosity in the 2-20 nm pore diameter range and an amorphous or crystalline inorganic framework. These materials are nowadays routinely prepared by combining soft chemistry and supramolecular templating. Photocatalytic transparent coatings and titania-based solar cells are the immediate promising applications. However, a wealth of new prospective uses have emerged on the horizon, such as advanced catalysts, perm-selective membranes, optical materials based on plasmonics and photonics, metamaterials, biomaterials or new magnetic nanocomposites. Current and novel applications rely on the ultimate control of the materials features such as pore size and geometry, surface functionality and wall structure. Even if a certain control of these characteristics has been provided by the methods reported so far, the needs for the next generation of MTTF require a deeper insight in the physical and chemical processes taking place in their preparation and processing. This article presents a critical discussion of these aspects. This discussion is essential to evolve from know-how to sound knowledge, aiming at a rational materials design of these fascinating systems.Periodically ordered mesoporous titania thin films (MTTF) present a high surface area, controlled porosity in the 2-20 nm pore diameter range and an amorphous or crystalline inorganic framework. These materials are nowadays routinely prepared by combining soft chemistry and supramolecular templating. Photocatalytic transparent coatings and titania-based solar cells are the immediate promising applications. However, a wealth of new prospective uses have emerged on the horizon, such as advanced catalysts, perm-selective membranes, optical materials based on plasmonics and photonics, metamaterials, biomaterials or new magnetic nanocomposites. Current and novel applications rely on the ultimate control of the materials features such as pore size and geometry, surface functionality and wall structure. Even if a certain control of these characteristics has been provided by the methods reported so far, the needs for the next generation of MTTF require a deeper insight in the physical and chemical processes taking place in their preparation and processing. This article presents a critical discussion of these aspects. This discussion is essential to evolve from know-how to sound knowledge, aiming at a rational materials design of these fascinating systems. Dedicated to Clément Sanchez, on the first anniversary of his appointment to the Hybrid Materials Chair of the Collège de France.

Structure and Properties of Azobenzene Thin-Films

NASA Astrophysics Data System (ADS)

Allen, R. A.

1987-09-01

Available from UMI in association with The British Library. A number of monomer and polymer materials, all containing the azobenzene group, have been deposited as Langmuir-Blodgett (LB) multilayers and their structures and physical properties studied. LB films of two monomeric materials exhibited liquid crystal phase changes that were investigated by optical microscopy and X-ray diffraction. Multilayers built up from one of the materials exhibited a phase change upon aging and this demonstrated that the LB technique had produced a structure that was not the equilibrium state. A monomer material possessing a fluorocarbon chain was found to initially deposit as an LB film in a Z-type manner, but changed to Y-type deposition with increasing multilayer thickness. A correlation was observed between this behaviour and the surface potential changes that were brought about when deposition took place on an aluminium substrate. The feasibility of building up alternating multilayers of monomer and polymer materials was demonstrated. Combining these two classes of material in the same LB film may confer on it the mechanical durability of the polymers and the highly ordered structure and potentially interesting physical properties of the monomer. The structures developed here may prove to have high second harmonic generation capabilities. Polymer materials were built up into relatively thick Y-type LB multilayers and studied by X-ray diffraction. Only poorly defined layered structures were found. Polymer materials were also cast into thin films from the melt and from solution. One of the compounds developed a high degree of anisotropy in its structure after exposure to linearly polarised white light. A birefringence of up to Deltan = 0.21 was measured. In contrast, LB films formed from the same material could not be ordered in the same manner and this appeared to result from the very close packing that takes place in such structures.

Fruit and vegetable films and uses thereof

USDA-ARS?s Scientific Manuscript database

The present invention is directed to monolayer, bilayer, and multilayer films made from fruit, vegetable or a combination thereof, which films have the thinness, strength, flexibility and crispness to serve as alternates or substitutes for seaweed-based films such as nori, while providing nutrition ...

Magnetic properties of Co-based multilayers with layer-alloyed modulations

NASA Astrophysics Data System (ADS)

Poulopoulos, P.; Angelakeris, M.; Niarchos, D.; Krishnan, R.; Porte, M.; Batas, C.; Flevaris, N. K.

1995-07-01

Various types of Co-based multilayers such as Pt mCo n, Pt m[CoPt] n, Co m[CoPd] n and Co m[CoPt] n were prepared by e-gun evaporation. Strong perpendicular anisotropy with considerable coercivity of ˜ 1 kOe was found for PtCo samples with thin Co layers. Moreover, the magnetization of Pt m[CoPt] n samples was found to approach that of pure Co and in the case of n > 5 enhancement of 30% or more exhibited. Magnetic properties were found to be strongly influenced by variations of modulation parameters.

Basic analysis of reflectometry data software package for the analysis of multilayered structures according to reflectometry data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Astaf'ev, S. B., E-mail: bard@ns.crys.ras.ru; Shchedrin, B. M.; Yanusova, L. G.

2012-01-15

The main principles of developing the Basic Analysis of Reflectometry Data (BARD) software package, which is aimed at obtaining a unified (standardized) tool for analyzing the structure of thin multilayer films and nanostructures of different nature based on reflectometry data, are considered. This software package contains both traditionally used procedures for processing reflectometry data and the authors' original developments on the basis of new methods for carrying out and analyzing reflectometry experiments. The structure of the package, its functional possibilities, examples of application, and prospects of development are reviewed.

Simulation of the microwave heating of a thin multilayered composite material: A parameter analysis

NASA Astrophysics Data System (ADS)

Tertrais, Hermine; Barasinski, Anaïs; Chinesta, Francisco

2018-05-01

Microwave (MW) technology relies on volumetric heating. Thermal energy is transferred to the material that can absorb it at specific frequencies. The complex physics involved in this process is far from being understood and that is why a simulation tool has been developed in order to solve the electromagnetic and thermal equations in such a complex material as a multilayered composite part. The code is based on the in-plane-out-of-plane separated representation within the Proper Generalized Decomposition framework. To improve the knowledge on the process, a parameter study in carried out in this paper.

Simple electrodepositing of CoFe/Cu multilayers: Effect of ferromagnetic layer thicknesses

NASA Astrophysics Data System (ADS)

Tekgül, Atakan; Alper, Mürsel; Kockar, Hakan

2017-01-01

The CoFe/Cu magnetic multilayers were produced by changing CoFe ferromagnetic layers from 3 nm to 10 nm using electrodeposition. By now, the thinnest Cu (0.5 nm) layer thicknesses were used to see whether the GMR effect in the multilayers can be obtained or not since the pinning of non-magnetic layer between the ferromagnetic layers is required. For the proper depositions, the cyclic voltammograms was used, and the current-time transients were obtained. The Cu and CoFe layers were deposited at a cathode potential of -0.3 and -1.5 V with respect to saturated calomel electrode, respectively. From the XRD patterns, the multilayers were shown to be fcc crystal structures. For the magnetization measurements, saturation magnetization increases from 160 to 600 kA/m from 3 to 8 nm ferromagnetic layer thicknesses. And, the coercivity values increase until the 8 nm of the CoFe layer thickness. It is seen that the thin Cu layer (fixed at 0.5 nm) and pinholes support the random magnetization orientation and thus all multilayers exhibited the giant magnetoresistance (GMR) effect, and the highest GMR value was observed about 5.5%. And, the variation of GMR field sensitivity was calculated. The results show that the GMR and GMR sensitivity are compatible among the multilayers. The CoFe/Cu magnetic multilayers having GMR properties are used in GMR sensors and hard disk drive of the nano-technological devices.

Nanolaminated FeCoB/FeCo and FeCoB/NiFe soft magnetic thin films with tailored magnetic properties deposited by magnetron sputtering

NASA Astrophysics Data System (ADS)

Hida, Rachid; Falub, Claudiu V.; Perraudeau, Sandrine; Morin, Christine; Favier, Sylvie; Mazel, Yann; Saghi, Zineb; Michel, Jean-Philippe

2018-05-01

Thin films based on layers of Fe52Co28B20 (at%), Fe65Co35 (at%), and Ni80Fe20 (at%) were deposited by sputtering on 8″ bare Si and Si/200 nm-thermal-SiO2 wafers by simultaneous use of two or more cathodes. Due to the continuous rotation of the substrate cage, such that the substrates faced different targets alternately, the multilayers consisted of stacks of alternating, nanometer-thick regular layers. The composition of the films was determined by Rutherford Backscattering Spectrometry (RBS) and Nuclear Reactive Analysis (NRA), whereas Plasma Profiling Time of Flight Mass Spectrometry (PP-TOFMS) analysis gave depth profile information about the chemical elements. The structural and magnetic properties of the films were investigated by X-ray Diffraction and by TEM analysis, B-H loop tracer and high frequency single coil technique permeametry, respectively. The linear dependence of the coercivity of these thin films versus the grain size can be explained by the random anisotropy model. These novel, composite soft magnetic multilayers, with tunable in-plane anisotropy, allow operation at tunable frequencies, as shown by broadband (between 100 MHz and 10 GHz) RF measurements that exhibit a classical Landau-Lifschitz-Gilbert (LLG) behavior and, combine the magnetic properties of the individual materials in an advantageous way. This article presents a method to produce nanostructured soft magnetic multilayers, the properties of which can easily be tuned by choosing the ratio of the individual nanolayers. In this way it's possible to combine soft magnetic materials with complementary properties, e.g. high saturation magnetization, low coercivity, high specific resistivity and low magnetostriction

Radiation damage effects in far-ultraviolet filters, thin films, and substrates.

PubMed

Keffer, C E; Torr, M R; Zukic, M; Spann, J F; Torr, D G; Kim, J

1994-09-01

Advances in vacuum ultraviolet thin-film filter technology have been made through the use of filter designs with multilayers of materials such as Al(2)O(3), BaF(2), CaF(2), HfO(2), LaF(3), MgF(2), and SiO(2). Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 × 9 R(E) orbit will expose the instrument to approximately 250 krad of radiation. Because to our knowledge no previous studies have been made on the potential radiation damage of these materials in the thin-film format, we report on such an assessment here. Transmittances and reflectances of BaF(2), CaF(2), HfO(2), MgF(2), and SiO(2) thin films on MgF(2) substrates, Al(2)O(3) thin films on fused-silica substrates, uncoated fused silica and MgF(2), and four multilayer filters made from these materials were measured from 120 to 180 nm beforeand after irradiation by 250 krad from a (60)Co gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 to 300 nm indicates 2-5% radiation-induced absorption near 260 nm in some of the samples with MgF(2) substrates. From these measurements we conclude that far-ultraviolet filters made from the materials tested should experience less than 5% change from exposure to up to 250 krad of high-energy radiation in space applications.

Cluster Beam Deposition of High Temperature Materials

DTIC Science & Technology

1991-01-01

include Secur y Classifocation) CLUSTER BEAM DEPOSITION OF HIGH TEMPERATURE MATERIALS 12 . PERSONAL AUTHOR(S) William J. Herron and James F. Garvey 13a TYPE... industria - applications (su:erconducting thin films, diamond-liKe !arbn,. films, patterned or multi-layered thin films, etc...) INT RODIU C’I 1 Recently there...Tne path of the expanc~ nr gas pulse passes perpendicularly (left to right in tne figure) over the surface of the target rod. I I Laser Beam-I I I Lens

Using high thermal stability flexible thin film thermoelectric generator at moderate temperature

NASA Astrophysics Data System (ADS)

Zheng, Zhuang-Hao; Luo, Jing-Ting; Chen, Tian-Bao; Zhang, Xiang-Hua; Liang, Guang-Xing; Fan, Ping

2018-04-01

Flexible thin film thermoelectric devices are extensively used in the microscale industry for powering wearable electronics. In this study, comprehensive optimization was conducted in materials and connection design for fabricating a high thermal stability flexible thin film thermoelectric generator. First, the thin films in the generator, including the electrodes, were prepared by magnetron sputtering deposition. The "NiCu-Cu-NiCu" multilayer electrode structure was applied to ensure the thermal stability of the device used at moderate temperature in an air atmosphere. A design with metal layer bonding and series accordant connection was then employed. The maximum efficiency of a single PN thermocouple generator is >11%, and the output power loss of the generator is <10% after integration.

MultiLayer solid electrolyte for lithium thin film batteries

DOEpatents

Lee, Se -Hee; Tracy, C. Edwin; Pitts, John Roland; Liu, Ping

2015-07-28

A lithium metal thin-film battery composite structure is provided that includes a combination of a thin, stable, solid electrolyte layer [18] such as Lipon, designed in use to be in contact with a lithium metal anode layer; and a rapid-deposit solid electrolyte layer [16] such as LiAlF.sub.4 in contact with the thin, stable, solid electrolyte layer [18]. Batteries made up of or containing these structures are more efficient to produce than other lithium metal batteries that use only a single solid electrolyte. They are also more resistant to stress and strain than batteries made using layers of only the stable, solid electrolyte materials. Furthermore, lithium anode batteries as disclosed herein are useful as rechargeable batteries.

Robust lanthanide emitters in polyelectrolyte thin films for photonic applications

NASA Astrophysics Data System (ADS)

Greenspon, Andrew S.; Marceaux, Brandt L.; Hu, Evelyn L.

2018-02-01

Trivalent lanthanides provide stable emission sources at wavelengths spanning the ultraviolet through the near infrared with uses in telecommunications, lighting, and biological sensing and imaging. We describe a method for incorporating an organometallic lanthanide complex within polyelectrolyte multilayers, producing uniform, optically active thin films on a variety of substrates. These films demonstrate excellent emission with narrow linewidths, stable over a period of months, even when bound to metal substrates. Utilizing different lanthanides such as europium and terbium, we are able to easily tune the resulting wavelength of emission of the thin film. These results demonstrate the suitability of this platform as a thin film emitter source for a variety of photonic applications such as waveguides, optical cavities, and sensors.

Higher Sensitivity in X-Ray Photography

NASA Technical Reports Server (NTRS)

Buggle, R. N.

1986-01-01

Hidden defects revealed if X-ray energy decreased as exposure progresses. Declining-potential X-ray photography detects fractures in thin metal sheet covered by unbroken sheet of twice thickness. Originally developed to check solder connections on multilayer circuit boards, technique has potential for other nondestructive testing.

Thin and Flexible Fe-Si-B/Ni-Cu-P Metallic Glass Multilayer Composites for Efficient Electromagnetic Interference Shielding.

PubMed

Zhang, Jijun; Li, Jiawei; Tan, Guoguo; Hu, Renchao; Wang, Junqiang; Chang, Chuntao; Wang, Xinmin

2017-12-06

Thin and flexible materials that can provide efficient electromagnetic interference (EMI) shielding are urgently needed, especially if they can be easily processed and withstand harsh environments. Herein, layer-structured Fe-Si-B/Ni-Cu-P metallic glass composites have been developed by simple electroless plating Ni-Cu-P coating on commercial Fe-Si-B metallic glasses. The 0.1 mm-thick composite shows EMI shielding effectiveness of 40 dB over the X-band frequency range, which is higher than those of traditional metals, metal oxides, and their polymer composites of larger thickness. Most of the applied electromagnetic waves are proved to be absorbed rather than bounced back. This performance originates from the combination of a superior soft magnetic property, excellent electrical conductivity, and multiple internal reflections from multilayer composites. In addition, the flexible composites also exhibit good corrosion resistance, high thermal stability, and excellent tensile strength, making them suitable for EMI shielding in harsh chemical or thermal environments.

On the single-photon-counting (SPC) modes of imaging using an XFEL source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhehui

In this study, the requirements to achieve high detection efficiency (above 50%) and gigahertz (GHz) frame rate for the proposed 42-keV X-ray free-electron laser (XFEL) at Los Alamos are summarized. Direct detection scenarios using C (diamond), Si, Ge and GaAs semiconductor sensors are analyzed. Single-photon counting (SPC) mode and weak SPC mode using Si can potentially meet the efficiency and frame rate requirements and be useful to both photoelectric absorption and Compton physics as the photon energy increases. Multilayer three-dimensional (3D) detector architecture, as a possible means to realize SPC modes, is compared with the widely used two-dimensional (2D) hybridmore » planar electrode structure and 3D deeply entrenched electrode architecture. Demonstration of thin film cameras less than 100-μm thick with onboard thin ASICs could be an initial step to realize multilayer 3D detectors and SPC modes for XFELs.« less

On the single-photon-counting (SPC) modes of imaging using an XFEL source

DOE PAGES

Wang, Zhehui

2015-12-14

In this study, the requirements to achieve high detection efficiency (above 50%) and gigahertz (GHz) frame rate for the proposed 42-keV X-ray free-electron laser (XFEL) at Los Alamos are summarized. Direct detection scenarios using C (diamond), Si, Ge and GaAs semiconductor sensors are analyzed. Single-photon counting (SPC) mode and weak SPC mode using Si can potentially meet the efficiency and frame rate requirements and be useful to both photoelectric absorption and Compton physics as the photon energy increases. Multilayer three-dimensional (3D) detector architecture, as a possible means to realize SPC modes, is compared with the widely used two-dimensional (2D) hybridmore » planar electrode structure and 3D deeply entrenched electrode architecture. Demonstration of thin film cameras less than 100-μm thick with onboard thin ASICs could be an initial step to realize multilayer 3D detectors and SPC modes for XFELs.« less

Fabrication of multilayered thin films via spin-assembly

DOEpatents

Chiarelli, Peter A.; Robinson, Jeanne M.; Casson, Joanna L.; Johal, Malkiat S.; Wang, Hsing-Lin

2007-02-20

An process of forming multilayer thin film heterostructures is disclosed and includes applying a solution including a first water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species onto a substrate to form a first coating layer on the substrate, drying the first coating layer on the substrate, applying a solution including a second water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species onto the substrate having the first coating layer to form a second coating layer on the first coating layer wherein the second water-soluble polymer is of a different material than the first water-soluble polymer, and drying the second coating layer on the first coating layer so as to form a bilayer structure on the substrate. Optionally, one or more additional applying and drying sequences can be repeated with a water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species, so that a predetermined plurality of layers are built up upon the substrate.

Nonvolatile memory characteristics of organic thin film transistors using poly(2-hydroxyethyl methacrylate)-based polymer multilayer dielectric

NASA Astrophysics Data System (ADS)

Chen, Ying-Chih; Su, Yan-Kuin; Yu, Hsin-Chieh; Huang, Chun-Yuan; Huang, Tsung-Syun

2011-10-01

A wide hysteresis width characteristic (memory window) was observed in the organic thin film transistors (OTFTs) using poly(2-hydroxyethyl methacrylate) (PHEMA)-based polymer multilayers. In this study, a strong memory effect was also found in the pentacene-based OTFTs and the electric characteristics were improved by introducing PHEMA/poly(methyl methacrylate) (PMMA)/PHEMA trilayer to replace the conventional PHEMA monolayer or PMMA/PHEMA and PHEMA/PMMA bilayer as the dielectric layers of OTFTs. The memory effect was originated from the electron trapping and slow polarization of the dielectrics. The hydroxyl (-OH) groups inside the polymer dielectric were the main charge storage sites of the electrons. This charge-storage phenomenon could lead to a wide flat-band voltage shift (memory window, △VFB = 22 V) which is essential for the OTFTs' memory-related applications. Moreover, the fabricated transistors also exhibited significant switchable channel current due to the charge-storage and slow charge relaxation.

Maskless deposition technique for the physical vapor deposition of thin film and multilayer coatings with subnanometer precision and accuracy

DOEpatents

Vernon, Stephen P.; Ceglio, Natale M.

2000-01-01

The invention is a method for the production of axially symmetric, graded and ungraded thickness thin film and multilayer coatings that avoids the use of apertures or masks to tailor the deposition profile. A motional averaging scheme permits the deposition of uniform thickness coatings independent of the substrate radius. Coating uniformity results from an exact cancellation of substrate radius dependent terms, which occurs when the substrate moves at constant velocity. If the substrate is allowed to accelerate over the source, arbitrary coating profiles can be generated through appropriate selection and control of the substrate center of mass equation of motion. The radial symmetry of the coating profile is an artifact produced by orbiting the substrate about its center of mass; other distributions are obtained by selecting another rotation axis. Consequently there is a direct mapping between the coating thickness and substrate equation of motion which can be used to tailor the coating profile without the use of masks and apertures.

Microstructure-related properties at 193 nm of MgF2 and GdF3 films deposited by a resistive-heating boat.

PubMed

Liu, Ming-Chung; Lee, Cheng-Chung; Kaneko, Masaaki; Nakahira, Kazuhide; Takano, Yuuichi

2006-03-01

MgF2 and GdF3 materials, used for a single-layer coating at 193 nm, are deposited by a resistive-heating boat at specific substrate temperatures. Optical characteristics (transmittance, refractive index, extinction coefficient, and optical loss) and microstructures (morphology and crystalline structure) are investigated and discussed. Furthermore, MgF2 is used as a low-index material, and GdF3 is used as a high-index material for multilayer coatings. Reflectance, stress, and the laser-induced damage threshold (LIDT) are studied. It is shown that MgF2 and GdF3 thin films, deposited on the substrate at a temperature of 300 degrees C, obtain good quality thin films with high transmittance and little optical loss at 193 nm. For multilayer coatings, the stress mainly comes from MgF2, and the absorption comes from GdF3. Among those coatings, the sixteen-layer design, sub/(1.4L 0.6H)8/air, shows the largest LIDT.

Influence of substrate temperatures on the properties of GdF(3) thin films with quarter-wave thickness in the ultraviolet region.

PubMed

Jin, Jingcheng; Jin, Chunshui; Li, Chun; Deng, Wenyuan; Yao, Shun

2015-06-01

High-quality coatings of fluoride materials are in extraordinary demand for use in deep ultraviolet (DUV) lithography. Gadolinium fluoride (GdF₃) thin films were prepared by a thermal boat evaporation process at different substrate temperatures. GdF₃ thin film was set at quarter-wave thickness (∼27  nm) with regard to their common use in DUV/vacuum ultraviolet optical stacks; these thin films may significantly differ in nanostructural properties at corresponding depositing temperatures, which would crucially influence the performance of the multilayers. The measurement and analysis of optical, structural, and mechanical properties of GdF₃ thin films have been performed in a comprehensive characterization cycle. It was found that depositing GdF₃ thin films at relative higher temperature would form a rather dense, smooth, homogeneous structure within this film thickness scale.

Production and Performance of the InFOCmicronS 20-40 keV Graded Multilayer Mirror

NASA Technical Reports Server (NTRS)

Berendse, F.; Owens, S. M.; Serlemitsos, P. J.; Tueller, J.; Chan, K.-W.; Soong, Y.; Krimm, H.; Baumgartner, W. H.; Tamura, K.; Okajima, T.;

Micromachined Thin-Film Sensors for SOI-CMOS Co-Integration

NASA Astrophysics Data System (ADS)

Laconte, Jean; Flandre, D.; Raskin, Jean-Pierre

Co-integration of sensors with their associated electronics on a single silicon chip may provide many significant benefits regarding performance, reliability, miniaturization and process simplicity without significantly increasing the total cost. Micromachined Thin-Film Sensors for SOI-CMOS Co-integration covers the challenges and interests and demonstrates the successful co-integration of gas flow sensors on dielectric membrane, with their associated electronics, in CMOS-SOI technology. We firstly investigate the extraction of residual stress in thin layers and in their stacking and the release, in post-processing, of a 1 μm-thick robust and flat dielectric multilayered membrane using Tetramethyl Ammonium Hydroxide (TMAH) silicon micromachining solution.

Analysis of the tunable asymmetric fiber F-P cavity for fiber sensor edge-filter demodulation

NASA Astrophysics Data System (ADS)

Chen, Haitao; Liang, Youcheng

2014-12-01

An asymmetric fiber (Fabry-Pérot,F-P) interferometric cavity with good linearity and wide dynamic range is successfully designed basing on optical thin film characteristic matrix theory; by choosing the material of two different thin metallic layers, the asymmetric fiber F-P interferometric cavity is fabricated by depositing the multi-layer thin films on the optical fiber's end face. The demodulation method for the wavelength shift of fiber Bragg grating (FBG) sensor basing on the F-P cavity is demonstrated and a theoretical formula is obtained. And the experimental results coincide well with computational results obtained from the theoretical model.

Multilayer ZnO/Pd/ZnO Structure as Sensing Membrane for Extended-Gate Field-Effect Transistor (EGFET) with High pH Sensitivity

NASA Astrophysics Data System (ADS)

Rasheed, Hiba S.; Ahmed, Naser M.; Matjafri, M. Z.; Al-Hardan, Naif H.; Almessiere, Munirah Abdullah; Sabah, Fayroz A.; Al-Hazeem, Nabeel Z.

2017-10-01

Metal oxide nanostructures have attracted considerable attention as pH-sensitive membranes because of their unique advantages. Specifically, the special properties of ZnO thin film, including high surface-to-volume ratio, nontoxicity, thermal stability, chemical stability, electrochemical activity, and high mechanical strength, have attracted massive interest. ZnO exhibits wide bandgap of 3.37 eV, good biocompatibility, high reactivity, robustness, and environmental stability. These unique properties explain why ZnO has the most applications among all nanostructured metal oxides based on its structure and properties. Moreover, ZnO has excellent electrical characteristics, enabling its use in accurate sensors with rapid response. ZnO nanostructures can be used in novel pH and biomedical sensing applications. However, ZnO thin film exhibits large sheet resistance and low conductivity. Increasing the conductivity or reducing the resistivity of ZnO sensing membranes is important to achieve low impedance. We propose herein a new design using a multilayer ZnO/Pd/ZnO structure as a pH-sensing membrane. Multiple layers were deposited by radio frequency (RF) sputtering for ZnO and direct current (DC) sputtering for Pd to achieve low sheet resistance. These multilayers with low sheet resistance of 15.8 Ω/sq were then successfully used to control the conductivity in extended-gate field-effect transistors (EGFETs). The resulting multilayered EGFET pH-sensor demonstrated improved sensing performance. The measured sensitivity of the pH sensor was 40 μA/pH and 52 mV/pH within the pH range from 2 to 12, rendering this structure suitable for use in various applications, including pH sensors and biosensors.

Performance Investigation of Multilayer MoS2 Thin-Film Transistors Fabricated via Mask-free Optically Induced Electrodeposition.

PubMed

Li, Meng; Liu, Na; Li, Pan; Shi, Jialin; Li, Guangyong; Xi, Ning; Wang, Yuechao; Liu, Lianqing

2017-03-08

Transition metal dichalcogenides, particularly MoS 2 , have recently received enormous interest in explorations of the physics and technology of nanodevice applications because of their excellent optical and electronic properties. Although monolayer MoS 2 has been extensively investigated for various possible applications, its difficulty of fabrication renders it less appealing than multilayer MoS 2 . Moreover, multilayer MoS 2 , with its inherent high electronic/photonic state densities, has higher output driving capabilities and can better satisfy the ever-increasing demand for versatile devices. Here, we present multilayer MoS 2 back-gate thin-film transistors (TFTs) that can achieve a relatively low subthreshold swing of 0.75 V/decade and a high mobility of 41 cm 2 ·V -1 ·s -1 , which exceeds the typical mobility value of state-of-the-art amorphous silicon-based TFTs by a factor of 80. Ag and Au electrode-based MoS 2 TFTs were fabricated by a convenient and rapid process. Then we performed a detailed analysis of the impacts of metal contacts and MoS 2 film thickness on electronic performance. Our findings show that smoother metal contacts exhibit better electronic characteristics and that MoS 2 film thickness should be controlled within a reasonable range of 30-40 nm to obtain the best mobility values, thereby providing valuable insights regarding performance enhancement for MoS 2 TFTs. Additionally, to overcome the limitations of the conventional fabrication method, we employed a novel approach known as optically induced electrodeposition (OIE), which allows the flexible and precise patterning of metal films and enables rapid and mask-free device fabrication, for TFT fabrication.

Enhancement of the barrier performance in organic/inorganic multilayer thin-film structures by annealing of the parylene layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Namsu, E-mail: nkim@keti.re.kr; Components and Materials Physics Research Center, #68 Yatop-dong, Korea Electronics Technology Institute, Bundang-gu, 463-816; Graham, Samuel

2014-10-15

Highlights: • High performance thin-film barrier structure for encapsulation was fabricated. • By annealing parylene in encapsulation structure, the barrier performance was improved. • The effective water vapor transmission rate is 7.2 ± 3.0 × 10{sup −6} g/m{sup 2}/day. - Abstract: A multilayered barrier structure was fabricated by chemical vapor deposition of parylene and subsequent plasma-enhanced chemical vapor deposition of SiO{sub x} or SiN{sub x}. The barrier performance against water vapor ingress was significantly improved by annealing the parylene layer before the deposition of either SiO{sub x} or SiN{sub x}. The mechanism of this enhancement was investigated using atomic forcemore » microscopy, Raman spectroscopy, and X-ray diffraction. The surface roughness of the parylene before the deposition of either SiO{sub x} or SiN{sub x} was found to correlate closely with the barrier performance of the multilayered structures. In addition, removing absorbed water vapor in the film by annealing results in a lower water vapor transmission rate in the transient region and a longer lag time. Annealing the parylene leads to a large decrease in the effective water vapor transmission rate, which reaches 7.2 ± 3.0 × 10{sup −6} g/m{sup 2}/day.« less

Thermal conductivity measurement of amorphous dielectric multilayers for phase-change memory power reduction

NASA Astrophysics Data System (ADS)

Fong, S. W.; Sood, A.; Chen, L.; Kumari, N.; Asheghi, M.; Goodson, K. E.; Gibson, G. A.; Wong, H.-S. P.

2016-07-01

In this work, we investigate the temperature-dependent thermal conductivities of few nanometer thick alternating stacks of amorphous dielectrics, specifically SiO2/Al2O3 and SiO2/Si3N4. Experiments using steady-state Joule-heating and electrical thermometry, while using a micro-miniature refrigerator over a wide temperature range (100-500 K), show that amorphous thin-film multilayer SiO2/Si3N4 and SiO2/Al2O3 exhibit through-plane room temperature effective thermal conductivities of about 1.14 and 0.48 W/(m × K), respectively. In the case of SiO2/Al2O3, the reduced conductivity is attributed to lowered film density (7.03 → 5.44 × 1028 m-3 for SiO2 and 10.2 → 8.27 × 1028 m-3 for Al2O3) caused by atomic layer deposition of thin-films as well as a small, finite, and repeating thermal boundary resistance (TBR) of 1.5 m2 K/GW between dielectric layers. Molecular dynamics simulations reveal that vibrational mismatch between amorphous oxide layers is small, and that the TBR between layers is largely due to imperfect interfaces. Finally, the impact of using this multilayer dielectric in a dash-type phase-change memory device is studied using finite-element simulations.

High efficient light absorption and nanostructure-dependent birefringence of a metal-dielectric symmetrical layered structure

NASA Astrophysics Data System (ADS)

Jen, Yi-Jun; Jhang, Yi-Ciang; Liu, Wei-Chih

2017-08-01

A multilayer that comprises ultra-thin metal and dielectric films has been investigated and applied as a layered metamaterial. By arranging metal and dielectric films alternatively and symmetrically, the equivalent admittance and refractive index can be tailored separately. The tailored admittance and refractive index enable us to design optical filters with more flexibility. The admittance matching is achieved via the admittance tracing in the normalized admittance diagram. In this work, an ultra-thin light absorber is designed as a multilayer composed of one or several cells. Each cell is a seven-layered film stack here. The design concept is to have the extinction as large as possible under the condition of admittance matching. For a seven-layered symmetrical film stack arranged as Ta2O5 (45 nm)/ a-Si (17 nm)/ Cr (30 nm)/ Al (30 nm)/ Cr (30 nm)/ a-Si (17 nm)/ Ta2O5 (45 nm), its mean equivalent admittance and extinction coefficient over the visible regime is 1.4+0.2i and 2.15, respectively. The unit cell on a transparent BK7 glass substrate absorbs 99% of normally incident light energy for the incident medium is glass. On the other hand, a transmission-induced metal-dielectric film stack is investigated by using the admittance matching method. The equivalent anisotropic property of the metal-dielectric multilayer varied with wavelength and nanostructure are investigated here.

Silicon carbide multilayer protective coating on carbon obtained by thermionic vacuum arc method

NASA Astrophysics Data System (ADS)

Ciupină, Victor; Lungu, Cristian Petrica; Vladoiu, Rodica; Prodan, Gabriel; Porosnicu, Corneliu; Belc, Marius; Stanescu, Iuliana M.; Vasile, Eugeniu; Rughinis, Razvan

2014-01-01

Thermionic vacuum arc (TVA) method is currently developing, in particular, to work easily with heavy fusible material for the advantage presented by control of directing energy for the elements forming a plasma. The category of heavy fusible material can recall C and W (high-melting point materials), and are difficult to obtain or to control by other means. Carbon is now used in many areas of special mechanical, thermal, and electrical properties. We refer in particular to high-temperature applications where unwanted effects may occur due to oxidation. Changed properties may lead to improper functioning of the item or device. For example, increasing the coefficient of friction may induce additional heat on moving items. One solution is to protect the item in question by coating with proper materials. Silicon carbide (SiC) was chosen mainly due to compatibility with coated carbon substrate. Recently, SiC has been used as conductive transparent window for optical devices, particularly in thin film solar cells. Using the TVA method, SiC coatings were obtained as thin films (multilayer structures), finishing with a thermal treatment up to 1000°C. Structural properties and oxidation behavior of the multilayer films were investigated, and the measurements showed that the third layer acts as a stopping layer for oxygen. Also, the friction coefficient of the protected films is lower relative to unprotected carbon films.

Effect of Al2O3 encapsulation on multilayer MoSe2 thin-film transistors

NASA Astrophysics Data System (ADS)

Lee, Hyun Ah; Yeoul Kim, Seong; Kim, Jiyoung; Choi, Woong

2017-03-01

We report the effect of Al2O3 encapsulation on the device performance of multilayer MoSe2 thin-film transistors based on statistical investigation of 29 devices with a SiO2 bottom-gate dielectric. On average, Al2O3 encapsulation by atomic layer deposition increased the field-effect mobility from 10.1 cm2 V-1 s-1 to 14.8 cm2 V-1 s-1, decreased the on/off-current ratio from 8.5  ×  105 to 2.3  ×  105 and negatively shifted the threshold voltage from  -1.1 V to  -8.1 V. Calculation based on the Y-function method indicated that the enhancement of intrinsic carrier mobility occurred independently of the reduction of contact resistance after Al2O3 encapsulation. Furthermore, contrary to previous reports in the literature, we observe a negligible effect of thermal annealing on contact resistance and carrier mobility during the atomic layer deposition of Al2O3. These results demonstrate that Al2O3 encapsulation is a useful method for improving the carrier mobility of multilayer MoSe2 transistors, providing important implications on the application of MoSe2 and other 2D materials into high-performance transistors.

A concept for a soft gamma-ray concentrator using thin-film multilayer structures

NASA Astrophysics Data System (ADS)

Bloser, Peter F.; Shirazi, Farzane; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Tsavalas, John G.; Wong, Emily N.; Aliotta, Paul H.

2016-07-01

We are investigating the use of thin-film, multilayer structures to form optics capable of concentrating soft gamma rays with energies greater than 100 keV, beyond the reach of current grazing-incidence hard X-ray mirrors. Alternating layers of low- and high-density materials (e.g., polymers and metals) will channel soft gamma-ray photons via total external reflection. A suitable arrangement of bent structures will then concentrate the incident radiation to a point. Gamma-ray optics made in this way offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments. Following initial investigations conducted at Los Alamos National Laboratory, we have constructed and tested a prototype structure using spin coating combined with magnetron sputtering. We are now investigating whether it is possible to grow such flexible multi-layer structures with the required thicknesses and smoothness more quickly by using magnetron sputter and pulsed laser deposition techniques. We present the latest results of our fabrication and gamma-ray channeling tests, and describe our modeling of the sensitivity of potential concentrator-based telescope designs. If successful, this technology offers the potential for transformational increases in sensitivity while dramatically improving the system-level performance of future high-energy astronomy missions through reduced mass and complexity.

Interstitial Mo-Assisted Photovoltaic Effect in Multilayer MoSe2 Phototransistors.

PubMed

Kim, Sunkook; Maassen, Jesse; Lee, Jiyoul; Kim, Seung Min; Han, Gyuchull; Kwon, Junyeon; Hong, Seongin; Park, Jozeph; Liu, Na; Park, Yun Chang; Omkaram, Inturu; Rhyee, Jong-Soo; Hong, Young Ki; Yoon, Youngki

2018-03-01

Thin-film transistors (TFTs) based on multilayer molybdenum diselenide (MoSe 2 ) synthesized by modified atmospheric pressure chemical vapor deposition (APCVD) exhibit outstanding photoresponsivity (103.1 A W -1 ), while it is generally believed that optical response of multilayer transition metal dichalcogenides (TMDs) is significantly limited due to their indirect bandgap and inefficient photoexcitation process. Here, the fundamental origin of such a high photoresponsivity in the synthesized multilayer MoSe 2 TFTs is sought. A unique structural characteristic of the APCVD-grown MoSe 2 is observed, in which interstitial Mo atoms exist between basal planes, unlike usual 2H phase TMDs. Density functional theory calculations and photoinduced transfer characteristics reveal that such interstitial Mo atoms form photoreactive electronic states in the bandgap. Models indicate that huge photoamplification is attributed to trapped holes in subgap states, resulting in a significant photovoltaic effect. In this study, the fundamental origin of high responsivity with synthetic MoSe 2 phototransistors is identified, suggesting a novel route to high-performance, multifunctional 2D material devices for future wearable sensor applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of optical filters using multilayered porous silicon

NASA Astrophysics Data System (ADS)

Gaber, Noha; Khalil, Diaa; Shaarawi, Amr

2011-02-01

In this work we describe a method for fabricating optical filters using multilayered porous silicon 1D photonic structure. An electrochemical cell is constructed to control the porosity of variable layers in p-type Si wafers. Porous silicon multilayered structures are formed of λ/4 (or multiples) thin films that construct optical interference filters. By changing the anodizing current density of the cell during fabrication, different porosities can be obtained as the optical refractive index is a direct function of the layer porosity. To determine the morphology, the wavelength dependent refractive index n and absorption coefficient α, first, porous silicon free standing mono-layers have been fabricated at different conditions and characterized in the near infrared region (from 1000 to 2500nm). Large difference in refractive index (between 1.6 and 2.6) is obtained. Subsequently, multilayer structures have been fabricated and tested. Their spectral response has been measured and it shows good agreement with numerical simulations. A technique based on inserting etching breaks is adopted to ensure the depth homogeneity. The effect of differing etching/break times on the reproducibility of the filters is studied.

Portable mini-chamber for temperature dependent studies using small angle and wide angle x-ray scattering

NASA Astrophysics Data System (ADS)

Dev, Arun Singh; Kumar, Dileep; Potdar, Satish; Pandit, Pallavi; Roth, Stephan V.; Gupta, Ajay

2018-04-01

The present work describes the design and performance of a vacuum compatible portable mini chamber for temperature dependent GISAXS and GIWAXS studies of thin films and multilayer structures. The water cooled body of the chamber allows sample annealing up to 900 K using ultra high vacuum compatible (UHV) pyrolytic boron nitride heater, thus making it possible to study the temperature dependent evolution of structure and morphology of two-dimensional nanostructured materials. Due to its light weight and small size, the chamber is portable and can be accommodated at synchrotron facilities worldwide. A systematic illustration of the versatility of the chamber has been demonstrated at beamline P03, PETRA-III, DESY, Hamburg, Germany. Temperature dependent grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) measurements were performed on oblique angle deposited Co/Ag multilayer structure, which jointly revealed that the surface diffusion in Co columns in Co/Ag multilayer enhances by increasing temperature from RT to ˜573 K. This results in a morphology change from columnar tilted structure to densely packed morphological isotropic multilayer.

Nanoscale deformation mechanism of TiC/a-C nanocomposite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C. Q.; Pei, Y. T.; Shaha, K. P.

2009-06-01

This paper concentrates on the deformation behavior of amorphous diamondlike carbon composite materials. Combined nanoindentation and ex situ cross-sectional transmission electron microscopy investigations are carried out on TiC/a-C nanocomposite films, with and without multilayered structures deposited by pulse dc magnetron sputtering. It is shown that by controlling the distribution of nanocrystallites forming nanoscale multilayers, the system can be used as a 'microstructural ruler' that is able to distinguish various deformation patterns, which can be hardly detected otherwise in a homogeneous structure. It is shown that rearrangement of nanocrystallites and displacement of a-C matrix occur at length scales from tens ofmore » nanometer down to 1 nm. At submicrometer scale homogeneous nucleation of multiple shear bands has been observed within the nanocomposites. The multilayered structure in the TiC/a-C nanocomposite film contributes to an enhanced toughness.« less

Fabrication of 3D polypyrrole microstructures and their utilization as electrodes in supercapacitors

NASA Astrophysics Data System (ADS)

Ho, Vinh; Zhou, Cheng; Kulinsky, Lawrence; Madou, Marc

2013-12-01

We present a novel fabrication method for constructing three-dimensional (3D) conducting microstructures based on the controlled-growth of electrodeposited polypyrrole (PPy) within a lithographically patterned photoresist layer. PPy thin films, post arrays, suspended planes supported by post arrays and multi-layered PPy structures were fabricated. The performance of supercapacitors based on 3D PPy electrodes doped with dodecylbenzene sulfonate (DBS-) and perchlorate (ClO4-) anions was studied using cyclic voltammetry and galvanostatic charge/discharge tests. The highest specific capacitance obtained from the multi-layered PPy(ClO4) electrodes was 401 ± 18 mF cm-2, which is roughly twice as high as the highest specific capacitance of PPy-based supercapacitor reported thus far. The increase in capacitance is the result of higher surface area per unit footprint achieved through the fabrication of multi-layered 3D electrodes.

Strain-assisted magnetization reversal in Co/Ni multilayers with perpendicular magnetic anisotropy

PubMed Central

Gopman, D. B.; Dennis, C. L.; Chen, P. J.; Iunin, Y. L.; Finkel, P.; Staruch, M.; Shull, R. D.

2016-01-01

Multifunctional materials composed of ultrathin magnetic films with perpendicular magnetic anisotropy combined with ferroelectric substrates represent a new approach toward low power, fast, high density spintronics. Here we demonstrate Co/Ni multilayered films with tunable saturation magnetization and perpendicular anisotropy grown directly on ferroelectric PZT [Pb(Zr0.52Ti0.48)O3] substrate plates. Electric fields up to ±2 MV/m expand the PZT by 0.1% and generate at least 0.02% in-plane compression in the Co/Ni multilayered film. Modifying the strain with a voltage can reduce the coercive field by over 30%. We also demonstrate that alternating in-plane tensile and compressive strains (less than 0.01%) can be used to propagate magnetic domain walls. This ability to manipulate high anisotropy magnetic thin films could prove useful for lowering the switching energy for magnetic elements in future voltage-controlled spintronic devices. PMID:27297638

Soft X-ray imaging of thick carbon-based materials using the normal incidence multilayer optics.

PubMed

Artyukov, I A; Feschenko, R M; Vinogradov, A V; Bugayev, Ye A; Devizenko, O Y; Kondratenko, V V; Kasyanov, Yu S; Hatano, T; Yamamoto, M; Saveliev, S V

2010-10-01

The high transparency of carbon-containing materials in the spectral region of "carbon window" (lambda approximately 4.5-5nm) introduces new opportunities for various soft X-ray microscopy applications. The development of efficient multilayer coated X-ray optics operating at the wavelengths of about 4.5nm has stimulated a series of our imaging experiments to study thick biological and synthetic objects. Our experimental set-up consisted of a laser plasma X-ray source generated with the 2nd harmonics of Nd-glass laser, scandium-based thin-film filters, Co/C multilayer mirror and X-ray film UF-4. All soft X-ray images were produced with a single nanosecond exposure and demonstrated appropriate absorption contrast and detector-limited spatial resolution. A special attention was paid to the 3D imaging of thick low-density foam materials to be used in design of laser fusion targets.

Coating multilayer material with improved tribological properties obtained by magnetron sputtering

NASA Astrophysics Data System (ADS)

Mateescu, A. O.; Mateescu, G.; Balasoiu, M.; Pompilian, G. O.; Lungu, M.

2017-02-01

This work is based on the Patent no. RO 128094 B1, granted by the Romanian State Office for Inventions and Trademarks. The goal of the work is to obtain for investigations tribological coatings with multilayer structure with improved tribological properties, deposited by magnetron sputtering process from three materials (sputtering targets). Starting from compound chemical materials (TiC, TiB2 and WC), as sputtering targets, by deposition in argon atmosphere on polished stainless steel, we have obtained, based on the claims of the above patent, thin films of multilayer design with promising results regarding their hardness, elastic modulus, adherence, coefficient of friction and wear resistance. The sputtering process took place in a special sequence in order to ensure better tribological properties to the coating, comparing to those of the individual component materials. The tribological properties, such as the coefficient of friction, are evaluated using the tribometer test.

Ge nanocrystals embedded in ultrathin Si3N4 multilayers with SiO2 barriers

NASA Astrophysics Data System (ADS)

Bahariqushchi, R.; Gundogdu, Sinan; Aydinli, A.

2017-04-01

Multilayers of germanium nanocrystals (NCs) embedded in thin films of silicon nitride matrix separated with SiO2 barriers have been fabricated using plasma enhanced chemical vapor deposition (PECVD). SiGeN/SiO2 alternating bilayers have been grown on quartz and Si substrates followed by post annealing in Ar ambient from 600 to 900 °C. High resolution transmission electron microscopy (HRTEM) as well as Raman spectroscopy show good crystallinity of Ge confined to SiGeN layers in samples annealed at 900 °C. Strong compressive stress for SiGeN/SiO2 structures were observed through Raman spectroscopy. Size, as well as NC-NC distance were controlled along the growth direction for multilayer samples by varying the thickness of bilayers. Visible photoluminescence (PL) at 2.3 and 3.1 eV with NC size dependent intensity is observed and possible origin of PL is discussed.

Reduction of thermal conductivity in MnSi{sub 1.7} multi-layered thin films with artificially inserted Si interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurosaki, Y., E-mail: yosuke.kurosaki.uy@hitachi.com; Yabuuchi, S.; Nishide, A.

We report a lowered lattice thermal conductivity in nm-scale MnSi{sub 1.7}/Si multilayers which were fabricated by controlling thermal diffusions of Mn and Si atoms. The thickness of the constituent layers is 1.5–5.0 nm, which is comparable to the phonon mean free path of both MnSi{sub 1.7} and Si. By applying the above nanostructures, we reduced the lattice thermal conductivity down to half that of bulk MnSi{sub 1.7}/Si composite materials. The obtained value of 1.0 W/K m is the experimentally observed minimum in MnSi{sub 1.7}-based materials without any heavy element doping and close to the minimum thermal conductivity. We attribute the reduced latticemore » thermal conductivity to phonon scattering at the MnSi{sub 1.7}/Si interfaces in the multilayers.« less

Methods to induce perpendicular magnetic anisotropy in full-Heusler Co2FeSi thin layers in a magnetic tunnel junction structure

NASA Astrophysics Data System (ADS)

Shinohara, Koki; Suzuki, Takahiro; Takamura, Yota; Nakagawa, Shigeki

2018-05-01

In this study, to obtain perpendicular magnetic tunnel junctions (p-MTJs) using half-metallic ferromagnets (HMFs), several methods were developed to induce perpendicular magnetic anisotropy (PMA) in full-Heusler Co2FeSi (CFS) alloy thin layers in an MTJ multilayer composed of a layered CFS/MgO/CFS structure. Oxygen exposure at 2.0 Pa for 10 min after deposition of the bottom CFS layer was effective for obtaining PMA in the CFS layer. One of the reasons for the PMA is the formation of nearly ideal CFS/MgO interfaces due to oxygen exposure before the deposition of the MgO layer. The annealing process was effective for obtaining PMA in the top CFS layer capped with a Pd layer. PMA was clearly observed in the top CFS layer of a Cr(40 nm)/Pd(50 nm)/bottom CFS(0.6 nm)/MgO(2.0 nm)/top CFS(0.6 nm)/ Pd(10 nm) multilayer, where the top CFS and Pd thin films were deposited at RT and subsequently annealed at 300°C. In addition to the continuous layer growth of the films, the crystalline orientation alignment at the top CFS/Pd interface probably attributes to the origin of PMA at the top CFS layer.

Multilayer thin-film phantoms for axial contrast transfer function measurement in optical coherence tomography.

PubMed

Agrawal, Anant; Chen, Chao-Wei; Baxi, Jigesh; Chen, Yu; Pfefer, T Joshua

2013-07-01

In optical coherence tomography (OCT), axial resolution is one of the most critical parameters impacting image quality. It is commonly measured by determining the point spread function (PSF) based on a specular surface reflection. The contrast transfer function (CTF) provides more insights into an imaging system's resolving characteristics and can be readily generated in a system-independent manner, without consideration for image pixel size. In this study, we developed a test method for determination of CTF based on multi-layer, thin-film phantoms, evaluated using spectral- and time-domain OCT platforms with different axial resolution values. Phantoms representing six spatial frequencies were fabricated and imaged. The fabrication process involved spin coating silicone films with precise thicknesses in the 8-40 μm range. Alternating layers were doped with a specified concentration of scattering particles. Validation of layer optical properties and thicknesses were achieved with spectrophotometry and stylus profilometry, respectively. OCT B-scans were used to calculate CTFs and results were compared with convetional PSF measurements based on specular reflections. Testing of these phantoms indicated that our approach can provide direct access to axial resolution characteristics highly relevant to image quality. Furthermore, tissue phantoms based on our thin-film fabrication approach may have a wide range of additional applications in optical imaging and spectroscopy.

The numerical model of multi-layer insulation with a defined wrapping pattern immersed in superfluid helium

NASA Astrophysics Data System (ADS)

Malecha, Ziemowit; Lubryka, Eliza

2017-11-01

The numerical model of thin layers, characterized by a defined wrapping pattern can be a crucial element of many computational problems related to engineering and science. A motivating example is found in multilayer electrical insulation, which is an important component of superconducting magnets and other cryogenic installations. The wrapping pattern of the insulation can significantly affect heat transport and the performance of the considered instruments. The major objective of this study is to develop the numerical boundary conditions (BC) needed to model the wrapping pattern of thin insulation. An example of the practical application of the proposed BC includes the heat transfer of Rutherford NbTi cables immersed in super-fluid helium (He II) across thin layers of electrical insulation. The proposed BC and a mathematical model of heat transfer in He II are implemented in the open source CFD toolbox OpenFOAM. The implemented mathematical model and the BC are compared in the experiments. The study confirms that the thermal resistance of electrical insulation can be lowered by implementing the proper wrapping pattern. The proposed BC can be useful in the study of new patterns for wrapping schemes. The work has been supported by statutory funds from Polish Ministry for Science and Higher Education for the year of 2017.

Manipulation of Magnetic Textures in Thin Films and Devices

NASA Astrophysics Data System (ADS)

Tolley, Robert Douglas

Control and manipulation of magnetic textures is promising for the development of next-generation data storage, memory and processing technologies. Towards this goal, domain wall manipulation in two materials systems are presented here and thoroughly evaluated. Domain walls in ferrimagnetic Cobalt-Terbium alloys and multilayers are created, moved and stabilized via thermal gradients and a static magnetic field and exploit the unique properties of the system across the magnetic compensation point. The response of the systems to thermal gradients is observed via Kerr microscopy and used to determine the positioning of domain walls within patterned devices. Magnetic skyrmions are discovered in thin-film multilayered stacks using an Pt/Co/Os/Pt heterostructures where the thin Osmium layer is used to break interfacial symmetry and enhance the Dzyaloshinskii-Moriya interaction. The resulting skyrmions are manipulated using temperature, magnetic field, and electric current, and special attention is paid to their motion and nucleation behavior. Skyrmions are observed to be formed by low applied currents from nucleation sites and by collapse of stripe textures. Patterned wires allow for the observation of skyrmion nucleation behavior in free space, as well as defect sites, and real-time Kerr microscopy imaging is presented of skyrmion and stripe dynamics. These systems are evaluated from a perspective of their growth, patterning, measurement, and the novel behavior of the magnetic textures.

Multilayer integral method for simulation of eddy currents in thin volumes of arbitrary geometry produced by MRI gradient coils.

PubMed

Sanchez Lopez, Hector; Freschi, Fabio; Trakic, Adnan; Smith, Elliot; Herbert, Jeremy; Fuentes, Miguel; Wilson, Stephen; Liu, Limei; Repetto, Maurizio; Crozier, Stuart

2014-05-01

This article aims to present a fast, efficient and accurate multi-layer integral method (MIM) for the evaluation of complex spatiotemporal eddy currents in nonmagnetic and thin volumes of irregular geometries induced by arbitrary arrangements of gradient coils. The volume of interest is divided into a number of layers, wherein the thickness of each layer is assumed to be smaller than the skin depth and where one of the linear dimensions is much smaller than the remaining two dimensions. The diffusion equation of the current density is solved both in time-harmonic and transient domain. The experimentally measured magnetic fields produced by the coil and the induced eddy currents as well as the corresponding time-decay constants were in close agreement with the results produced by the MIM. Relevant parameters such as power loss and force induced by the eddy currents in a split cryostat were simulated using the MIM. The proposed method is capable of accurately simulating the current diffusion process inside thin volumes, such as the magnet cryostat. The method permits the priori-calculation of optimal pre-emphasis parameters. The MIM enables unified designs of gradient coil-magnet structures for an optimal mitigation of deleterious eddy current effects. Copyright © 2013 Wiley Periodicals, Inc.

Novel application of polyelectrolyte multilayers as nanoscopic closures with hermetic sealing.

PubMed

Marcott, Stephanie A; Ada, Sena; Gibson, Phillip; Camesano, Terri A; Nagarajan, R

2012-03-01

Closure systems for personnel protection applications, such as protective clothing or respirator face seals, should provide effective permeation barrier to toxic gases. Currently available mechanical closure systems based on the hook and loop types (example, Velcro) do not provide adequate barrier to gas permeation. To achieve hermetic sealing, we propose a nonmechanical, nanoscopic molecular closure system based on complementary polyelectrolyte multilayers, one with a polycation outermost layer and the other with a polyanion outermost layer. The closure surfaces were prepared by depositing polyelectrolyte multilayers under a variety of deposition conditions, on conformable polymer substrates (thin films of polyethylene teraphthalate, PET or polyimide, PI). The hermetic sealing property of the closures was evaluated by measuring the air flow resistance using the dynamic moisture permeation cell (DMPC) at different humidity conditions. The DMPC measurements show that the polyelectrolyte multilayer closures provide significantly large resistance to air flow, approximately 20-800 times larger than that possible with conventional hook and loop type closure systems, at all humidity levels (from 5 to 95% relative humidity). Hence, from the point of view of providing a hermetic seal against toxic gas permeation, the polyelectrolyte multilayer closures are viable candidates for further engineering development. However, the adhesive strength of the multilayer closures measured by atomic force microscopy suggests that the magnitude of adhesion is much smaller than what is possible with mechanical closures. Therefore, we envisage the development of a composite closure system combining the mechanical closure to provide strong adhesion and the multilayer closure to provide hermetic sealing. © 2012 American Chemical Society

Investigation of Electrical and Optical Properties of Highly Transparent TCO/Ag/TCO Multilayer.

PubMed

Kim, Sunbo; Lee, Jaehyeong; Dao, Vinh Ai; Ahn, Shihyun; Hussain, Shahzada Qamar; Park, Jinjoo; Jung, Junhee; Lee, Chan; Song, Bong-Shik; Choi, Byoungdeog; Lee, Youn-Jung; Iftiquar, S M; Yi, Junsin

2015-03-01

Transparent conductive oxides (TCOs) have been widely used as transparent electrodes for opto-electronic devices, such as solar cells, flat-panel displays, and light-emitting diodes, because of their unique characteristics of high optical transmittance and low electrical resistivity. Among various TCO materials, zinc oxide based films have recently received much attention because they have advantages over commonly used indium and tin-based oxide films. Most TCO films, however, exhibit valleys of transmittance in the wavelength range of 550-700 nm, lowering the average transmittance in the visible region and decreasing short-circuit current (Isc) of solar cells. A TCO/Ag/TCO multi-layer structure has emerged as an attractive alternative because it provides optical characteristics without the valley of transmittance compared with a 100-nm-thick single-layer TCO. In this article, we report the electrical, optical and surface properties of TCO/Ag/TCO. These multi-layers were deposited at room temperature with various Ag film thicknesses from 5 to 15 nm while the thickness of TCO thin film was fixed at 40 nm. The TCO/Ag/TCO multi-layer with a 10-nm-thick Ag film showed optimum transmittance in the visible (400-800 nm) wavelength region. These multi-layer structures have advantages over TCO layers of the same thickness.

Thermal analysis of continuous and patterned multilayer films in the presence of a nanoscale hot spot

NASA Astrophysics Data System (ADS)

Juang, Jia-Yang; Zheng, Jinglin

2016-10-01

Thermal responses of multilayer films play essential roles in state-of-the-art electronic systems, such as photo/micro-electronic devices, data storage systems, and silicon-on-insulator transistors. In this paper, we focus on the thermal aspects of multilayer films in the presence of a nanoscale hot spot induced by near field laser heating. The problem is set up in the scenario of heat assisted magnetic recording (HAMR), the next-generation technology to overcome the data storage density limit imposed by superparamagnetism. We characterized thermal responses of both continuous and patterned multilayer media films using transient thermal modeling. We observed that material configurations, in particular, the thermal barriers at the material layer interfaces crucially impact the temperature field hence play a key role in determining the hot spot geometry, transient response and power consumption. With a representative generic media model, we further explored the possibility of optimizing thermal performances by designing layers of heat sink and thermal barrier. The modeling approach demonstrates an effective way to characterize thermal behaviors of micro and nano-scale electronic devices with multilayer thin film structures. The insights into the thermal transport scheme will be critical for design and operations of such electronic devices.

Stable aqueous dispersions of functionalized multi-layer graphene by pulsed underwater plasma exfoliation of graphite

NASA Astrophysics Data System (ADS)

Meyer-Plath, Asmus; Beckert, Fabian; Tölle, Folke J.; Sturm, Heinz; Mülhaupt, Rolf

2016-02-01

A process was developed for graphite particle exfoliation in water to stably dispersed multi-layer graphene. It uses electrohydraulic shockwaves and the functionalizing effect of solution plasma discharges in water. The discharges were excited by 100 ns high voltage pulsing of graphite particle chains that bridge an electrode gap. The underwater discharges allow simultaneous exfoliation and chemical functionalization of graphite particles to partially oxidized multi-layer graphene. Exfoliation is caused by shockwaves that result from rapid evaporation of carbon and water to plasma-excited gas species. Depending on discharge energy and locus of ignition, the shockwaves cause stirring, erosion, exfoliation and/or expansion of graphite flakes. The process was optimized to produce long-term stable aqueous dispersions of multi-layer graphene from graphite in a single process step without requiring addition of intercalants, surfactants, binders or special solvents. A setup was developed that allows continuous production of aqueous dispersions of flake size-selected multi-layer graphenes. Due to the well-preserved sp2-carbon structure, thin films made from the dispersed graphene exhibited high electrical conductivity. Underwater plasma discharge processing exhibits high innovation potential for morphological and chemical modifications of carbonaceous materials and surfaces, especially for the generation of stable dispersions of two-dimensional, layered materials.

Engineering invitro cellular microenvironment using polyelectrolyte multilayer films to control cell adhesion and for drug delivery applications

NASA Astrophysics Data System (ADS)

Kidambi, Srivatsan

Over the past decades, the development of new methods for fabricating thin films that provide precise control of the three-dimensional topography and cell adhesion has generated lots of interest. These films could lead to significant advances in the fields of tissue engineering, drug delivery and biosensors which have become increasingly germane areas of research in the field of chemical engineering. The ionic layer-by-layer (LbL) assembly technique called "Polyelectrolyte Multilayers (PEMs)", introduced by Decher in 1991, has emerged as a versatile and inexpensive method of constructing polymeric thin films, with nanometer-scale control of ionized species. PEMs have long been utilized in such applications as sensors, eletrochromics, and nanomechanical thin films but recently they have also been shown to be excellent candidates for biomaterial applications. In this thesis, we engineered these highly customizable PEM thin films to engineer in vitro cellular microenvironments to control cell adhesion and for drug delivery applications. PEM films were engineered to control the adhesion of primary hepatocytes and primary neurons without the aid of adhesive proteins/ligands. We capitalized upon the differential cell attachment and spreading of primary hepatocytes and neurons on poly(diallyldimethylammoniumchloride) (PDAC) and sulfonated polystyrene (SPS) surfaces to make patterned co-cultures of primary hepatocytes/fibroblasts and primary neurons/astrocytes on the PEM surfaces. In addition, we developed self-assembled monolayer (SAM) patterns of m-d-poly(ethylene glycol) (m-dPEG) acid molecules onto PEMs. The created m-dPEG acid monolayer patterns on PEMs acted as resistive templates, and thus prevented further deposits of consecutive poly(anion)/poly(cation) pairs of charged particles and resulted in the formation of three-dimensional (3-D) patterned PEM films or selective particle depositions atop the original multilayer thin films. These new patterned and structured surfaces have potential applications in microelectronic devices and electro-optical and biochemical sensors. The PEG patterns developed are tunable at certain salt conditions and be removed from the PEM surface without affecting the PEM layers underneath the patterns. These removable surfaces provide an alternative method to form patterns of multiple particles, proteins and cells. This new approach provides an environmentally friendly and biocompatible route to designing versatile salt tunable surfaces. Finally, we illustrate the use of PEM films to engineer aptamer and siRNA based drug delivery systems.

Interface mediated enhanced mixing of multilayered Ni-Bi thin films by swift heavy ion irradiation

NASA Astrophysics Data System (ADS)

Siva, V.; Chettah, A.; Ojha, S.; Tripathi, A.; Kanjilal, D.; Sahoo, Pratap K.

2017-10-01

We report the effect of ion beam mixing of Ni/Bi multilayers using 100 MeV Au ions as a function of irradiation fluences. X-ray diffraction study reveals the higher magnitude of NiBi3 and NiBi phases compared to elemental Ni and Bi after ion irradiation. We observe an evolution of grainy structures to a molten-like surface with increasing ion fluences. These features were also reflected in the Rutherford Backscattering spectrometry spectra, in terms of the enhanced mixing with increasing ion fluences. The experimental findings were understood on the basis of inelastic thermal spike model calculations.

Deposition of thin silicon layers on transferred large area graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lupina, Grzegorz, E-mail: lupina@ihp-microelectronics.com; Kitzmann, Julia; Lukosius, Mindaugas

2013-12-23

Physical vapor deposition of Si onto transferred graphene is investigated. At elevated temperatures, Si nucleates preferably on wrinkles and multilayer graphene islands. In some cases, however, Si can be quasi-selectively grown only on the monolayer graphene regions while the multilayer islands remain uncovered. Experimental insights and ab initio calculations show that variations in the removal efficiency of carbon residuals after the transfer process can be responsible for this behavior. Low-temperature Si seed layer results in improved wetting and enables homogeneous growth. This is an important step towards realization of electronic devices in which graphene is embedded between two Si layers.

Exchange coupling in the complex magnetic multilayers

NASA Astrophysics Data System (ADS)

Uzdin, V. M.; Adamowicz, L.; Kocinski, P.

1996-06-01

Exchange coupling in the complex magnetic sandwich structures containing nonmagnetic (NM) and ferromagnetic (FM) layers composed of two different ferromagnetic metals has been studied within the framework of the quantum wells model. The strength of the exchange coupling in the multilayer structure with thin layers of a second ferromagnetic material inserted at the interface of FM/NM/FM sandwich was calculated at various physical situations. In one case the exponential dependence of the exchange coupling on the thickness of the interface ferromagnetic layer has been obtained in striking resemblance to the Parkin experimental results for magnetoresistance (S. S. P. Parkin, Phys. Rev. Lett., 71 (1993) 1641).

Oxidation preventative capping layer for deep-ultra-violet and soft x-ray multilayers

DOEpatents

Prisbrey, Shon T.

2004-07-06

The invention uses iridium and iridium compounds as a protective capping layer on multilayers having reflectivity in the deep ultra-violet to soft x-ray regime. The iridium compounds can be formed in one of two ways: by direct deposition of the iridium compound from a prepared target or by depositing a thin layer (e.g., 5-50 angstroms) of iridium directly onto an element. The deposition energy of the incoming iridium is sufficient to activate the formation of the desired iridium compound. The compounds of most interest are iridium silicide (IrSi.sub.x) and iridium molybdenide (IrMo.sub.x).

Diffusion barrier properties of single- and multilayered quasi-amorphous tantalum nitride thin films against copper penetration

NASA Astrophysics Data System (ADS)

Chen, G. S.; Chen, S. T.

2000-06-01

Tantalum-related thin films containing different amounts of nitrogen are sputter deposited at different argon-to-nitrogen flow rate ratios on (100) silicon substrates. Using x-ray diffractometry, transmission electron microscopy, composition and resistivity analyses, and bending-beam stress measurement technique, this work examines the impact of varying the nitrogen flow rate, particularly on the crystal structure, composition, resistivity, and residual intrinsic stress of the deposited Ta2N thin films. With an adequate amount of controlled, reactive nitrogen in the sputtering gas, thin films of the tantalum nitride of nominal formula Ta2N are predominantly amorphous and can exist over a range of nitrogen concentrations slightly deviated from stoichiometry. The single-layered quasi-amorphous Ta2N (a-Ta2N) thin films yield intrinsic compressive stresses in the range 3-5 GPa. In addition, the use of the 40-nm-thick a-Ta2N thin films with different nitrogen atomic concentrations (33% and 36%) and layering designs as diffusion barriers between silicon and copper are also evaluated. When subjected to high-temperature annealing, the single-layered a-Ta2N barrier layers degrade primarily by an amorphous-to-crystalline transition of the barrier layers. Crystallization of the single-layered stoichiometric a-Ta2N (Ta67N33) diffusion barriers occurs at temperatures as low as 450 °C. Doing so allows copper to preferentially penetrate through the grain boundaries or thermal-induced microcracks of the crystallized barriers and react with silicon, sequentially forming {111}-facetted pyramidal Cu3Si precipitates and TaSi2 Overdoping nitrogen into the amorphous matrix can dramatically increase the crystallization temperature to 600 °C. This temperature increase slows down the inward diffusion of copper and delays the formation of both silicides. The nitrogen overdoped Ta2N (Ta64N36) diffusion barriers can thus be significantly enhanced so as to yield a failure temperature 100 °C greater than that of the Ta67N33 diffusion barriers. Moreover, multilayered films, formed by alternately stacking the Ta67N33 and Ta64N36 layers with an optimized bilayer thickness (λ) of 10 nm, can dramatically reduce the intrinsic compressive stress to only 0.7 GPa and undergo high-temperature annealing without crystallization. Therefore, the Ta67N33/Ta64N36 multilayered films exhibit a much better barrier performance than the highly crystallization-resistant Ta64N36 single-layered films.

Using dairy ingredients to produce edible films and biodegradable packaging materials

USDA-ARS?s Scientific Manuscript database

Food packaging is comprised of multi-layers of films which are thin continuous sheets of synthetic polymers. Recently, major food retailers and consumers have become concerned about the waste that packaging generates and the scarce natural resources and energy used in its manufacture. They are deman...

Simultaneous parameter optimization of x-ray and neutron reflectivity data using genetic algorithms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Surendra, E-mail: surendra@barc.gov.in; Basu, Saibal

2016-05-23

X-ray and neutron reflectivity are two non destructive techniques which provide a wealth of information on thickness, structure and interracial properties in nanometer length scale. Combination of X-ray and neutron reflectivity is well suited for obtaining physical parameters of nanostructured thin films and superlattices. Neutrons provide a different contrast between the elements than X-rays and are also sensitive to the magnetization depth profile in thin films and superlattices. The real space information is extracted by fitting a model for the structure of the thin film sample in reflectometry experiments. We have applied a Genetic Algorithms technique to extract depth dependentmore » structure and magnetic in thin film and multilayer systems by simultaneously fitting X-ray and neutron reflectivity data.« less

Thin PDMS Films Using Long Spin Times or Tert-Butyl Alcohol as a Solvent

PubMed Central

Koschwanez, John H.; Carlson, Robert H.; Meldrum, Deirdre R.

2009-01-01

Thin polydimethylsiloxane (PDMS) films are frequently used in “lab on a chip” devices as flexible membranes. The common solvent used to dilute the PDMS for thin films is hexane, but hexane can swell the underlying PDMS substrate. A better solvent would be one that dissolves uncured PDMS but doesn't swell the underlying substrate. Here, we present protocols and spin curves for two alternatives to hexane dilution: longer spin times and dilution in tert-butyl alcohol. The thickness of the PDMS membranes under different spin speeds, spin times, and PDMS concentrations was measured using an optical profilometer. The use of tert-butyl alcohol to spin thin PDMS films does not swell the underlying PDMS substrate, and we have used these films to construct multilayer PDMS devices. PMID:19238212

Ferromagnetic resonance linewidth and damping in perpendicular-anisotropy magnetic multilayers thin films

NASA Astrophysics Data System (ADS)

Beaujour, Jean-Marc

2010-03-01

Transition metal ferromagnetic films with perpendicular magnetic anisotropy (PMA) have ferromagnetic resonance (FMR) linewidths that are one order of magnitude larger than soft magnetic materials, such as pure iron (Fe) and permalloy (NiFe) thin films. We have conducted systematic studies of a variety of thin film materials with perpendicular magnetic anisotropy to investigate the origin of the enhanced FMR linewidths, including Ni/Co and CoFeB/Co/Ni multilayers. In Ni/Co multilayers the PMA was systematically reduced by irradiation with Helium ions, leading to a transition from out-of-plane to in-plane easy axis with increasing He ion fluence [1,2]. The FMR linewidth depends linearly on frequency for perpendicular applied fields and increases significantly when the magnetization is rotated into the film plane with an applied in-plane magnetic field. Irradiation of the film with Helium ions decreases the PMA and the distribution of PMA parameters, leading to a large reduction in the FMR linewidth for in-plane magnetization. These results suggest that fluctuations in the PMA lead to a large two magnon scattering contribution to the linewidth for in-plane magnetization and establish that the Gilbert damping is enhanced in such materials (α˜0.04, compared to α˜0.002 for pure Fe) [2]. We compare these results to those on CoFeB/Co/Ni and published results on other thin film materials with PMA [e.g., Ref. 3]. [1] D. Stanescu et al., J. Appl. Phys. 103, 07B529 (2008). [2] J-M. L. Beaujour, D. Ravelosona, I. Tudosa, E. Fullerton, and A. D. Kent, Phys. Rev. B RC 80, 180415 (2009). [3] N. Mo, J. Hohlfeld, M. ulIslam, C. S. Brown, E. Girt, P. Krivosik, W. Tong, A. Rebel, and C. E. Patton, Appl. Phys. Lett. 92, 022506 (2008). *Research done in collaboration with: A. D. Kent, New York University, D. Ravelosona, Institut d'Electronique Fondamentale, UMR CNRS 8622, Universit'e Paris Sud, E. E. Fullerton, Center for Magnetic Recording Research, UCSD, and supported by NSF-DMR-0706322.

Precise Control of the Number of Layers of Graphene by Picosecond Laser Thinning.

PubMed

Lin, Zhe; Ye, Xiaohui; Han, Jinpeng; Chen, Qiao; Fan, Peixun; Zhang, Hongjun; Xie, Dan; Zhu, Hongwei; Zhong, Minlin

2015-06-26

The properties of graphene can vary as a function of the number of layers (NOL). Controlling the NOL in large area graphene is still challenging. In this work, we demonstrate a picosecond (ps) laser thinning removal of graphene layers from multi-layered graphene to obtain desired NOL when appropriate pulse threshold energy is adopted. The thinning process is conducted in atmosphere without any coating and it is applicable for graphene films on arbitrary substrates. This method provides many advantages such as one-step process, non-contact operation, substrate and environment-friendly, and patternable, which will enable its potential applications in the manufacturing of graphene-based electronic devices.

Precise Control of the Number of Layers of Graphene by Picosecond Laser Thinning

NASA Astrophysics Data System (ADS)

Lin, Zhe; Ye, Xiaohui; Han, Jinpeng; Chen, Qiao; Fan, Peixun; Zhang, Hongjun; Xie, Dan; Zhu, Hongwei; Zhong, Minlin

2015-06-01

The properties of graphene can vary as a function of the number of layers (NOL). Controlling the NOL in large area graphene is still challenging. In this work, we demonstrate a picosecond (ps) laser thinning removal of graphene layers from multi-layered graphene to obtain desired NOL when appropriate pulse threshold energy is adopted. The thinning process is conducted in atmosphere without any coating and it is applicable for graphene films on arbitrary substrates. This method provides many advantages such as one-step process, non-contact operation, substrate and environment-friendly, and patternable, which will enable its potential applications in the manufacturing of graphene-based electronic devices.

Very low-refractive-index optical thin films consisting of an array of SiO2 nanorods

NASA Astrophysics Data System (ADS)

Xi, J.-Q.; Kim, Jong Kyu; Schubert, E. F.; Ye, Dexian; Lu, T.-M.; Lin, Shawn-Yu; Juneja, Jasbir S.

2006-03-01

The refractive-index contrast in dielectric multilayer structures, optical resonators, and photonic crystals is an important figure of merit that creates a strong demand for high-quality thin films with a low refractive index. A SiO2 nanorod layer with low refractive index of n=1.08, to our knowledge the lowest ever reported in thin-film materials, is grown by oblique-angle electron-beam deposition of SiO2. A single-pair distributed Bragg reflector employing a SiO2 nanorod layer is demonstrated to have enhanced reflectivity, showing the great potential of low-refractive-index films for applications in photonic structures and devices.

Corrosion-resistant multilayer structures with improved reflectivity

DOEpatents

Soufli, Regina; Fernandez-Perea, Monica; Robinson, Jeff C.

2013-04-09

In one general embodiment, a thin film structure includes a substrate; a first corrosion barrier layer above the substrate; a reflective layer above the first corrosion barrier layer, wherein the reflective layer comprises at least one repeating set of sub-layers, wherein one of the sub-layers of each set of sub-layers being of a corrodible material; and a second corrosion barrier layer above the reflective layer. In another general embodiment, a system includes an optical element having a thin film structure as recited above; and an image capture or spectrometer device. In a further general embodiment, a laser according to one embodiment includes a light source and the thin film structure as recited above.

Broadly tunable thin-film intereference coatings: active thin films for telecom applications

NASA Astrophysics Data System (ADS)

Domash, Lawrence H.; Ma, Eugene Y.; Lourie, Mark T.; Sharfin, Wayne F.; Wagner, Matthias

2003-06-01

Thin film interference coatings (TFIC) are the most widely used optical technology for telecom filtering, but until recently no tunable versions have been known except for mechanically rotated filters. We describe a new approach to broadly tunable TFIC components based on the thermo-optic properties of semiconductor thin films with large thermo-optic coefficients 3.6X10[-4]/K. The technology is based on amorphous silicon thin films deposited by plasma-enhanced chemical vapor deposition (PECVD), a process adapted for telecom applications from its origins in the flat-panel display and solar cell industries. Unlike MEMS devices, tunable TFIC can be designed as sophisticated multi-cavity, multi-layer optical designs. Applications include flat-top passband filters for add-drop multiplexing, tunable dispersion compensators, tunable gain equalizers and variable optical attenuators. Extremely compact tunable devices may be integrated into modules such as optical channel monitors, tunable lasers, gain-equalized amplifiers, and tunable detectors.

Synthesis and characterization of Copper/Cobalt/Copper/Iron nanostructurated films with magnetoresistive properties

NASA Astrophysics Data System (ADS)

Ciupinǎ, Victor; Prioteasa, Iulian; Ilie, Daniela; Manu, Radu; Petrǎşescu, Lucian; Tutun, Ştefan Gabriel; Dincǎ, Paul; MustaÅ£ǎ, Ion; Lungu, Cristian Petricǎ; Jepu, IonuÅ£; Vasile, Eugeniu; Nicolescu, Virginia; Vladoiu, Rodica

2017-02-01

Copper/Cobalt/Copper/Iron thin films were synthesized in order to obtain nanostructured materials with special magnetoresistive properties. The multilayer films were deposited on silicon substrates. In this respect we used Thermionic Vacuum Arc Discharge Method (TVA). The benefit of this deposition technique is the ability to have a controlled range of thicknesses starting from few nanometers to hundreds of nanometers. The purity of the thin films was insured by a high vacuum pressure and a lack of any kind of buffer gas inside the coating chamber. The morphology and structure of the thin films were analyzed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) Techniques and Energy Dispersive X-ray Spectroscopy (EDXS). Magnetoresistive measurement results depict that thin films possess Giant Magneto-Resistance Effect (GMR). Magneto-Optic-Kerr Effect (MOKE) studies were performed to characterize the magnetic properties of these thin films.

Thermal stress prediction in mirror and multilayer coatings.

PubMed

Cheng, Xianchao; Zhang, Lin; Morawe, Christian; Sanchez Del Rio, Manuel

2015-03-01

Multilayer optics for X-rays typically consist of hundreds of periods of two types of alternating sub-layers which are coated on a silicon substrate. The thickness of the coating is well below 1 µm (tens or hundreds of nanometers). The high aspect ratio (∼10(7)) between the size of the optics and the thickness of the multilayer can lead to a huge number of elements (∼10(16)) for the numerical simulation (by finite-element analysis using ANSYS code). In this work, the finite-element model for thermal-structural analysis of multilayer optics has been implemented using the ANSYS layer-functioned elements. The number of meshed elements is considerably reduced and the number of sub-layers feasible for the present computers is increased significantly. Based on this technique, single-layer coated mirrors and multilayer monochromators cooled by water or liquid nitrogen are studied with typical parameters of heat-load, cooling and geometry. The effects of cooling-down of the optics and heating of the X-ray beam are described. It is shown that the influences from the coating on temperature and deformation are negligible. However, large stresses are induced in the layers due to the different thermal expansion coefficients between the layer and the substrate materials, which is the critical issue for the survival of the optics. This is particularly true for the liquid-nitrogen cooling condition. The material properties of thin multilayer films are applied in the simulation to predict the layer thermal stresses with more precision.

Porting of the transfer-matrix method for multilayer thin-film computations on graphics processing units

NASA Astrophysics Data System (ADS)

Limmer, Steffen; Fey, Dietmar

2013-07-01

Thin-film computations are often a time-consuming task during optical design. An efficient way to accelerate these computations with the help of graphics processing units (GPUs) is described. It turned out that significant speed-ups can be achieved. We investigate the circumstances under which the best speed-up values can be expected. Therefore we compare different GPUs among themselves and with a modern CPU. Furthermore, the effect of thickness modulation on the speed-up and the runtime behavior depending on the input data is examined.

Basic optics of effect materials.

PubMed

Jones, Steven A

2010-01-01

Effect materials derive their color and effect primarily from thin-film interference. Effect materials have evolved over the decades from simple guanine crystals to the complex multilayer optical structures of today. The development of new complex effect materials requires an understanding of the optics of effect materials. Such an understanding would also benefit the cosmetic formulator as these new effect materials are introduced. The root of this understanding begins with basic optics. This paper covers the nature of light, interference of waves, thin-film interference, color from interference, and color travel.

Improvement of silicon solar cell performance through the use of thin film coatings.

PubMed

Reynard, D L; Andrew, A

1966-01-01

Thin film coatings are used universally in solar cell power systems for spacecraft. Antireflective coatings are used to increase the amount of useful energy reaching the active surface of the cell. Multilayer interference filters are employed to reject unwanted portions of the solar spectrum in order to reduce equilibrium temperature and to prevent ultraviolet damage. Glass covers are used in conjunction with these coatings for the purpose of increasing the thermal emittance of the surface. Appreciable performance increases can be obtained through the uses of these filters and coatings.

Superlattice Multinanolayered Thin Films of SiO2/SiO2 + Ge for Thermoelectric Device Applications

DTIC Science & Technology

2013-04-05

radioiso- tope sources in the past. In a space nuclear reactor system, the energy source is the heat generated by the controlled fission of uranium ...to the nanodots and/or nanocluster formations in the multilayered thin films. This is one of the expected results of the ion beam bombardments on...very large (150 W m 1 K 1 for Si and 63 W m 1 K 1 for Ge). The lattice thermal conductivity can be substantially reduced by alloy formation between

Reflectance, Optical Properties, and Stability of Molybdenum/Strontium and Molybdenum/Yttrium Multilayer Mirrors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kjornrattanawanich, Benjawan

2002-09-01

The motivation of this work is to develop high reflectance normal-incidence multilayer mirrors in the 8-12 nm wavelength region for applications in astronomy and extreme ultraviolet lithography. To achieve this goal, Mo/Sr and Mo/Y multilayers were studied. These multilayers were deposited with a UHV magnetron sputtering system and their reflectances were measured with synchrotron radiation. High normal-incidence reflectances of 23% at 8.8 nm, 40.8% at 9.4 nm, and 48.3% at 10.5 nm were achieved. However, the reflectance of Mo/Sr multilayers decreased rapidly after exposure to air. Attempts to use thin layers of carbon to passivate the surface of Mo/Sr multilayers were unsuccessful. Experimental results on the refractive indexmore » $$\\tilde{n}$$ = 1-δ + iβ of yttrium and molybdenum in the 50-1300 eV energy region are reported in this work. This is the first time ever that values on the refractive index of yttrium are measured in this energy range. The absorption part β was determined through transmittance measurements. The dispersive part δ was calculated by means of the Kramers-Kronig formalism. The newly determined values of the refractive index of molybdenum are in excellent agreement with the published data. Those of yttrium are more accurate and contain fine structures around the yttrium M-absorption edges where Mo/Y multilayers operate. These improved sets of optical data lead to better design and modeling of the optical properties of Mo/Y multilayers. The reflectance quality of Mo/Y multilayers is dependent on their optical and structural properties. To correlate these properties with the multilayer reflectance, x-ray diffraction, Rutherford backscattering spectrometry, and transmission electron microscopy were used to analyze samples. Normal-incidence reflectances of 32.6% at 9.27 nm, 38.4% at 9.48 nm, and 29.6% at 9.46 nm were obtained from three representative Mo/Y multilayers which had about 0%, 25%, and 39% atomic oxygen assimilated in their yttrium layers, respectively. Based on the optical properties, multilayers with higher oxygen content should have higher absorption. However, the 25%-oxygen multilayer had less interface roughness and thus had higher reflectance than the 0%-oxygen sample. The 39%-oxygen multilayer had the highest absorption and roughness, thus had the lowest reflectance among three samples. The optical and structural properties of the multilayers are competing in the reflectance results.« less

Sol-gel thin-film based mesoporous silica and carbon nanotubes for the determination of dopamine, uric acid and paracetamol in urine.

PubMed

Canevari, Thiago C; Raymundo-Pereira, Paulo A; Landers, Richard; Benvenutti, Edilson V; Machado, Sérgio A S

2013-11-15

This work describes the preparation, characterization and application of a hybrid material composed of disordered mesoporous silica (SiO2) modified with multiwalled carbon nanotubes (MWCNTs), obtained by the sol-gel process using HF as the catalyst. This hybrid material was characterized by N2 adsorption-desorption isotherms, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HR-TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This new hybrid material was used for the construction of a thin film on a glassy carbon electrode. The modified electrode using this material was designated SiO2/MWCNT/GCE. The electrocatalytic properties of the electrode toward dopamine, uric acid and paracetamol oxidation were studied by differential pulse voltammetry. Well-defined and separated oxidation peaks were observed in phosphate buffer solution at pH 7.0, in contrast with the ill-defined peaks observed with unmodified glassy carbon electrodes. The electrode had high sensitivity for the determination of dopamine, uric acid and paracetamol, with the limits of detection obtained using statistical methods, at 0.014, 0.068 and 0.098 µmol L(-1), respectively. The electrode presented some important advantages, including enhanced physical rigidity, surface renewability by polishing and high sensitivity, allowing the simultaneous determination of these three analytes in a human urine sample. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Ordered mesoporous MFe(2)O(4) (M = Co, Cu, Mg, Ni, Zn) thin films with nanocrystalline walls, uniform 16 nm diameter pores and high thermal stability: template-directed synthesis and characterization of redox active trevorite.

PubMed

Haetge, Jan; Suchomski, Christian; Brezesinski, Torsten

2010-12-20

In this paper, we report on ordered mesoporous NiFe(2)O(4) thin films synthesized via co-assembly of hydrated ferric nitrate and nickel chloride with an amphiphilic diblock copolymer, referred to as KLE. We establish that the NiFe(2)O(4) samples are highly crystalline after calcination at 600 °C, and that the conversion of the amorphous inorganic framework comes at little cost to the ordering of the high quality cubic network of pores averaging 16 nm in diameter. We further show that the synthesis method employed in this work can be readily extended to other ferrites, such as CoFe(2)O(4), CuFe(2)O(4), MgFe(2)O(4), and ZnFe(2)O(4), which could pave the way for innovative device design. While this article focuses on the self-assembly and characterization of these materials using various state-of-the-art techniques, including electron microscopy, grazing incidence small-angle X-ray scattering (GISAXS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), as well as UV-vis and Raman spectroscopy, we also examine the electrochemical properties and show the benefits of combining a continuous mesoporosity with nanocrystalline films. KLE-templated NiFe(2)O(4) electrodes exhibit reasonable levels of lithium ion storage at short charging times which stem from facile pseudocapacitance.

Substrate-Independent Robust and Heparin-Mimetic Hydrogel Thin Film Coating via Combined LbL Self-Assembly and Mussel-Inspired Post-Cross-linking.

PubMed

Ma, Lang; Cheng, Chong; He, Chao; Nie, Chuanxiong; Deng, Jie; Sun, Shudong; Zhao, Changsheng

2015-12-02

In this work, we designed a robust and heparin-mimetic hydrogel thin film coating via combined layer-by-layer (LbL) self-assembly and mussel-inspired post-cross-linking. Dopamine-grafted heparin-like/-mimetic polymers (DA-g-HepLP) with abundant carboxylic and sulfonic groups were synthesized by the conjugation of adhesive molecule, DA, which exhibited substrate-independent adhesive affinity to various solid surfaces because of the formation of irreversible covalent bonds. The hydrogel thin film coated substrates were prepared by a three-step reaction: First, the substrates were coated with DA-g-HepLP to generate negatively charged surfaces. Then, multilayers were obtained via LbL coating of chitosan and the DA-g-HepLP. Finally, the noncovalent multilayers were oxidatively cross-linked by NaIO4. Surface ATR-FTIR and XPS spectra confirmed the successful fabrication of the hydrogel thin film coatings onto membrane substrates; SEM images revealed that the substrate-independent coatings owned 3D porous morphology. The soaking tests in highly alkaline, acid, and concentrated salt solutions indicated that the cross-linked hydrogel thin film coatings owned high chemical resistance. In comparison, the soaking tests in physiological solution indicated that the cross-linked hydrogel coatings owned excellent long-term stability. The live/dead cell staining and morphology observations of the adhered cells revealed that the heparin-mimetic hydrogel thin film coated substrates had low cell toxicity and high promotion ability for cell proliferation. Furthermore, systematic in vitro investigations of protein adsorption, platelet adhesion, blood clotting, and blood-related complement activation confirmed that the hydrogel film coated substrates showed excellent hemocompatibility. Both the results of inhibition zone and bactericidal activity indicated that the gentamycin sulfate loaded hydrogel thin films had significant inhibition capability toward both Escherichia coli and Staphylococcus aureus bacteria. Combined the above advantages, it is believed that the designed heparin-mimetic hydrogel thin films may show high potential for applications in various biological and clinical fields, such as long-term hemocompatible and drug-loading materials for implants.

Self-assembly of dodecaphenyl POSS thin films

NASA Astrophysics Data System (ADS)

Handke, Bartosz; Klita, Łukasz; Niemiec, Wiktor

2017-12-01

The self-assembly abilities of Dodecaphenyl Polyhedral Oligomeric Silsesquioxane thin films on Si(1 0 0) surfaces were studied. Due to their thermal properties - relatively low sublimation temperature and preservation of molecular structure - cage type silsesquioxanes are ideal material for the preparation of a thin films by Physical Vapor Deposition. The Ultra-High Vacuum environment and the deposition precision of the PVD method enable the study of early stages of thin film growth and its molecular organization. X-ray Reflectivity and Atomic Force Microscopy measurements allow to pursuit size-effects in the structure of thin films with thickness ranges from less than a single molecular layer up to several tens of layers. Thermal treatment of the thin films triggered phase change: from a poorly ordered polycrystalline film into a well-ordered multilayer structure. Self-assembly of the layers is the effect of the π-stacking of phenyl rings, which force molecules to arrange in a superlattice, forming stacks of alternating organic-inorganic layers.

Structural and electrical characterization of annealed Si1-xCx/SiC thin film prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Huang, Shi-Hua; Liu, Jian

2014-05-01

Si-rich Si1—xCx /SiC multilayer thin films are prepared using magnetron sputtering, subsequently followed by thermal annealing in the range of 800-1200 °C. The influences of annealing temperature (Ta) on the formation of Si and/or SiC nanocrystals (NCs) and on the electrical characteristics of the multilayer film are investigated by using a variety of analytical techniques, including X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectrometry (FT-IR), current—voltage (I—V) technique, and capacitance-voltage (C—V) technique. XRD and Raman analyses indicate that Si NCs begin to form in samples for Ta >= 800 °C. At annealing temperatures of 1000 °C or higher, the formation of Si NCs is accompanied by the formation of SiC NCs. With the increase in the annealing temperature, the shift of FT-IR Si—C bond absorption spectra toward a higher wave number along with the change of band shape can be explained by a Si—C transitional phase between the loss of substitutional carbon and the formation of SiC precipitates and a precursor for the growth of SiC crystalline. The C—V and I—V results indicate that the interface quality of Si1—xCx/SiC multilayer film is improved significantly and the leakage current is reduced rapidly for Ta >= 1000 °C, which can be ascribed to the formation of Si and SiC NCs.

Spin and orbital magnetic moments of Fe and Co in Co/Fe and Fe/Co multilayers on Si from L2,3 edge X-ray Magnetic Circular Dichroism Spectroscopy

NASA Astrophysics Data System (ADS)

Vemuru, Krishnamurthy; Rosenberg, Richard; Mankey, Gary

Nanostructured FeCo thin films are interesting for magnetic recording applications due to their high saturation magnetization, high Curie temperature and low magnetocrystalline anisotropy. It is desirable to know how the magnetism is modified by the nanostructrure. We report Fe L 2 , 3 edge and Co L2 , 3 edge x-ray magnetic circular dichroism (XMCD) investigations of element specific spin and orbital magnetism of Fe and Co in two multilayer samples: (S1) Si/SiO2/[Co 0.8 nm/Fe 1.6 nm]x32/W (2nm) and (S2) Si/SiO2/[Co 1.6 nm/Fe 0.8 nm]x32/W (2nm) thin films at room temperature. Sum rule analysis of XMCD at Fe L2 , 3 edge in sample S1 shows that the orbital moment of Fe is strongly enhanced and the spin moment is strongly reduced as compared to the values found in bulk Fe. Details of sum rule analysis will be presented to compare and contrast spin magnetic moments and orbital magnetic moments of Fe and Co in the two multilayer samples. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Science and Technology of Nanostructured Magnetic Materials

DTIC Science & Technology

1990-07-06

galvano-magnetic and magneto-optic effects that can lead to future storage technologies. Ultrafine particles also show interesting and unique properties...areas including thin films, multilayers, disordered systems, ultrafine particles , intermetallic compounds, permanent magnets and magnetic imaging... ultrafine particles , intermetallic compounds, permanent magnets and magnetic imaging techniques. The development of new techniques for materials preparation

Intumescent all-polymer multilayer nanocoating capable of extinguishing flame on fabric

USDA-ARS?s Scientific Manuscript database

Cotton fabric was treated with flame-retardant coatings composed of poly (sodium phosphate), PSP, which acts as the acid source, and poly (allylamine), PAAm, which is used as the blowing agent, prepared via layer-by-layer (LbL) assembly. By applying these thin coating on fabric, after-glow is elimi...

Quantitative Diagnostics of Multilayered Composite Structures with Ultrasonic Guided Waves

DTIC Science & Technology

2014-09-01

sensors. These IDT sensors were fabricated from thin wafer of piezoelectric lead zirconate titanate ( PZT ) substrates by using a pulse laser micro...pavement structures," J. Acoust. Soc. Am., vol. 116, no. 5, pp. 2902-2913, 2004. [9] E. Kostson and P. Fromme, " Fatigue crack growth monitoring in multi

Control of excitons in multi-layer van der Waals heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calman, E. V., E-mail: ecalman@gmail.com; Dorow, C. J.; Fogler, M. M.

2016-03-07

We report an experimental study of excitons in a double quantum well van der Waals heterostructure made of atomically thin layers of MoS{sub 2} and hexagonal boron nitride. The emission of neutral and charged excitons is controlled by gate voltage, temperature, and both the helicity and the power of optical excitation.

High color fidelity thin film multilayer systems for head-up display use

NASA Astrophysics Data System (ADS)

Tsou, Yi-Jen D.; Ho, Fang C.

1996-09-01

Head-up display is gaining increasing access in automotive vehicles for indication and position/navigation purposes. An optical combiner, which allows the driver to receive image information from outside and inside of the automobile, is the essential part of this display device. Two multilayer thin film combiner coating systems with distinctive polarization selectivity and broad band spectral neutrality are discussed. One of the coating systems was designed to be located at the lower portion of the windshield. The coating reduced the exterior glare by approximately 45% and provided about 70% average see-through transmittance in addition to the interior information display. The other coating system was designed to be integrated with the sunshield located at the upper portion of the windshield. The coating reflected the interior information display while reducing direct sunlight penetration to 25%. Color fidelity for both interior and exterior images were maintained in both systems. This facilitated the display of full-color maps. Both coating systems were absorptionless and environmentally durable. Designs, fabrication, and performance of these coating systems are addressed.

Au Nanoparticle Sub-Monolayers Sandwiched between Sol-Gel Oxide Thin Films

PubMed Central

Della Gaspera, Enrico; Menin, Enrico; Sada, Cinzia

2018-01-01

Sub-monolayers of monodisperse Au colloids with different surface coverage have been embedded in between two different metal oxide thin films, combining sol-gel depositions and proper substrates functionalization processes. The synthetized films were TiO2, ZnO, and NiO. X-ray diffraction shows the crystallinity of all the oxides and verifies the nominal surface coverage of Au colloids. The surface plasmon resonance (SPR) of the metal nanoparticles is affected by both bottom and top oxides: in fact, the SPR peak of Au that is sandwiched between two different oxides is centered between the SPR frequencies of Au sub-monolayers covered with only one oxide, suggesting that Au colloids effectively lay in between the two oxide layers. The desired organization of Au nanoparticles and the morphological structure of the prepared multi-layered structures has been confirmed by Rutherford backscattering spectrometry (RBS), Secondary Ion Mass Spectrometry (SIMS), and Scanning Electron Microscopy (SEM) analyses that show a high quality sandwich structure. The multi-layered structures have been also tested as optical gas sensors. PMID:29538338

Design and development of multilayer wideband antireflection coating and its annealing study

NASA Astrophysics Data System (ADS)

Jena, S.; Tokas, R. B.; Udupa, D. V.; Thakur, S.; Sahoo, N. K.

2018-04-01

Reflection loss occurs at the glass-air interface, limits performance of many optical devices such as eyeglass, camera lenses, and photovoltaic solar cells. Antireflection (AR) coating on the glass reduces the reflection loss and improves efficiency of such devices. In this paper, wideband AR coating in the visible region has been designed and developed using ZrO2-MgO/SiO2 multilayer. The thicknesses of individual thin layers are numerically optimized to get maximum transmission of the visible light. The optimized four thin layers have been deposited on BK7 glass substrate using electron beam evaporation technique. The measured transmission spectrum of the 4-layer AR coating is compared with that of simulated spectrum. The transmission of the single side AR coating increases by more than 3% as compared to that of bare glass substrate in the wavelength region of 470 nm - 810 nm. The wideband AR coating has been annealed at 200°C for 4 hours in ambient condition. The transmission of the AR coating decreases after the annealing, resulting degradation in its wideband AR characteristics.

Influence of cellulose nanocrystals concentration and ionic strength on the elaboration of cellulose nanocrystals-xyloglucan multilayered thin films.

PubMed

Dammak, Abir; Moreau, Céline; Azzam, Firas; Jean, Bruno; Cousin, Fabrice; Cathala, Bernard

2015-12-15

The effect of the variation of CNC concentration on the growth pattern of CNC-XG films is investigated. We found that a transition in the growth slope occurs at a CNC concentration of roughly 3-4gL(-1). A close effect can be obtained by the increase of the ionic strength of the CNC suspensions, suggesting that electrostatic interactions are involved. Static light scattering investigation of CNC dispersions at increasing concentrations demonstrated that the particle-particle interactions change as the CNC concentration increases. Neutron Reflectivity (NR) was used to probe the internal structure of the films. The increase of the CNC concentration as well as the increase of the ionic strength in the CNC suspension were found to induce a densification of the adsorbed CNC layers, even though the mechanisms are not strictly identical in both cases. Small changes in these parameters provide a straightforward way of controlling the architecture of CNC-based multilayered thin films and, as a result, their functional properties. Copyright © 2015 Elsevier Inc. All rights reserved.

Measurement of Two-Phase Flow and Heat Transfer Parameters using Infrared Thermometry

NASA Technical Reports Server (NTRS)

Kim, Tae-Hoon; Kommer, Eric; Dessiatoun, Serguei; Kim, Jungho

2012-01-01

A novel technique to measure heat transfer and liquid film thickness distributions over relatively large areas for two-phase flow and heat transfer phenomena using infrared (IR)thermometry is described. IR thermometry is an established technology that can be used to measure temperatures when optical access to the surface is available in the wavelengths of interest. In this work, a midwave IR camera (3.6-5.1 microns) is used to determine the temperature distribution within a multilayer consisting of a silicon substrate coated with a thin insulator. Since silicon is largely transparent to IR radiation, the temperature of the inner and outer walls of the multilayer can be measured by coating selected areas with a thin, IR opaque film. If the fluid used is also partially transparent to IR, the flow can be visualized and the liquid film thickness can be measured. The theoretical basis for the technique is given along with a description of the test apparatus and data reduction procedure. The technique is demonstrated by determining the heat transfer coefficient distributions produced by droplet evaporation and flow boiling heat transfer.

Tuning electro-optic susceptibity via strain engineering in artificial PZT multilayer films for high-performance broadband modulator

NASA Astrophysics Data System (ADS)

Zhu, Minmin; Du, Zehui; Li, Hongling; Chen, Bensong; Jing, Lin; Tay, Roland Ying Jie; Lin, Jinjun; Tsang, Siu Hon; Teo, Edwin Hang Tong

2017-12-01

A series of Pb(Zr1-xTix)O3 multilayer films alternatively stacked by Pb(Zr0.52Ti0.48)O3 and Pb(Zr0.35Ti0.65)O3 layers have been deposited on corning glass by magnetron sputtering. The films demonstrate pure perovskite structure and good crystallinity. A large tetragonality (c/a) of ∼1.061 and a shift of ∼0.08 eV for optical bandgap were investigated at layer engineered films. In addition, these samples exhibited a wild tunable electro-optic behavior from tens to ∼250.2 pm/V, as well as fast switching time of down to a few microseconds. The giant EO coefficient was attribute the strain-polarization coupling effect and also comparable to that of epitaxial (001) single crystal PZT thin films. The combination of high transparency, large EO effect, fast switching time, and huge phase transition temperature in PZT-based thin films show the potential on electro-optics from laser to information telecommunication.

Assembly of luminescent ordered multilayer thin-films based on oppositely-charged MMT and magnetic NiFe-LDHs nanosheets with ultra-long lifetimes

PubMed Central

Liu, Meitang; Wang, Tianlei; Ma, Hongwen; Fu, Yu; Hu, Kunran; Guan, Chao

2014-01-01

In this present report, luminescent ordered multilayer thin films (OMFs) based on oppositely-charged inorganic nanosheets and the different oppositely-charged chromophores were fabricated via layer-by-layer assembly method. Exfoliated layered double hydroxides (LDHs) and montmorillonite (MMT) nanosheets with opposite charges can be expected to provide a pseudo electronic microenvironment (PEM) which has not been declared in previous literatures, and transition metal-bearing LDHs nanosheets can offer an additional ferromagnetic effect (FME) for the chromophores at the same time. Surprisingly, the luminescent lifetimes of those OMFs with PEM and FME are significantly prolonged compared with that of the pristine chromophores, even much longer than those of OMFs without oppositely-charged and ferromagnetic architecture. Therefore, it is highly expected that the PEM and FME formed by oppositely-charged and transition metal-bearing inorganic nanosheets have remarkable influence on obtaining better optical property, which suggests a new potential way to manipulate, control and develop the novel light-emitting materials and optical devices. PMID:25413710

Optically transparent thin-film transistors based on 2D multilayer MoS₂ and indium zinc oxide electrodes.

PubMed

Kwon, Junyeon; Hong, Young Ki; Kwon, Hyuk-Jun; Park, Yu Jin; Yoo, Byungwook; Kim, Jiwan; Grigoropoulos, Costas P; Oh, Min Suk; Kim, Sunkook

2015-01-21

We report on optically transparent thin film transistors (TFTs) fabricated using multilayered molybdenum disulfide (MoS2) as the active channel, indium tin oxide (ITO) for the back-gated electrode and indium zinc oxide (IZO) for the source/drain electrodes, respectively, which showed more than 81% transmittance in the visible wavelength. In spite of a relatively large Schottky barrier between MoS2 and IZO, the n-type behavior with a field-effect mobility (μ(eff)) of 1.4 cm(2) V(-1) s(-1) was observed in as-fabricated transparent MoS2 TFT. In order to enhance the performances of transparent MoS2 TFTs, a picosecond pulsed laser was selectively irradiated onto the contact region of the IZO electrodes. Following laser annealing, μ(eff) increased to 4.5 cm(2) V(-1) s(-1), and the on-off current ratio (I(on)/I(off)) increased to 10(4), which were attributed to the reduction of the contact resistance between MoS2 and IZO.

Biodegradable multilayer barrier films based on alginate/polyethyleneimine and biaxially oriented poly(lactic acid).

PubMed

Gu, Chun-Hong; Wang, Jia-Jun; Yu, Yang; Sun, Hui; Shuai, Ning; Wei, Bing

2013-02-15

A layer-by-layer (LBL) approach was used to assemble alternating layers of sodium alginate (ALG)/polyethyleneimine (PEI) on biaxially oriented poly(lactic acid) (BOPLA) films in order to produce bio-based all-polymer thin films with low gas permeability. Increasing the depositing of ALG and PEI from 0 to 30 layers results in large thickness variations (from 0 to 3.92 μm). After 30 ALG/PEI layers are deposited, the resulting assembly has an OTR of 1.22 cm(3)/(m(2) day atm). When multiplied by thickness, the resulting oxygen permeability (OP) is found to be less than 3.8×10(-17) cm(3) cm/cm(2) s Pa, which is almost 3 orders of magnitude lower than that of uncoated BOPLA film (1.8×10(-14) cm(3)cm/cm(2) s Pa). At the same time, the resulting multilayer-coated BOPLA films maintain high optical clarity and tensile properties. This unique barrier thin film has become a promising alternative to non-biodegradable synthetic food packaging materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

Gas Suppression via Copper Interlayers in Magnetron Sputtered Al-Cu2O Multilayers.

PubMed

Kinsey, Alex H; Slusarski, Kyle; Sosa, Steven; Weihs, Timothy P

2017-07-05

The use of thin-foil, self-propagating thermite reactions to bond components successfully depends on the ability to suppress gas generation and avoid pore formation during the exothermic production of brazes. To study the mechanisms of vapor production in diluted thermites, thin film multilayer Al-Cu-Cu 2 O-Cu foils are produced via magnetron sputtering, where the Cu layer thickness is systematically increased from 0 to 100 nm in 25 nm increments. The excess Cu layers act as diffusion barriers, limiting the transport of oxygen from the oxide to the Al fuel, as determined by slow heating differential scanning calorimetry experiments. Furthermore, by adding excess Cu to the system, the temperature of the self-propagating thermite reactions drops below the boiling point of Cu, eliminating the metal vapor production. It is determined that Cu vapor production can be eliminated by increasing the Cu interlayer thickness above 50 nm. However, the porous nature of the final products suggests that only metal vapor production is suppressed via dilution. Gas generation via oxygen release is still capable of producing a porous reaction product.

Wideband acoustic wave resonators composed of hetero acoustic layer structure

NASA Astrophysics Data System (ADS)

Kadota, Michio; Tanaka, Shuji

2018-07-01

“Hetero acoustic layer (HAL) surface acoustic wave (SAW) device” is a new type of SAW device using a single crystal piezoelectric thin plate supported by a substrate. In this study, a HAL SAW resonator using a LiNbO3 (LN) thin plate and a multi-layer acoustic film was designed by finite element method (FEM) and fabricated. The thickness of LN is 3.6 µm and the pitch of an interdigital transducer (IDT) (λ) is 5.24 µm for a resonance frequency of 600 MHz. The multi-layer acoustic film is composed of 3 layers of SiO2 and AlN for each, i.e., 6 layers in total, alternately deposited on a glass substrate. The HAL SAW resonator achieved a wide bandwidth of 20.3% and a high impedance ratio of 83 dB. Compared with a 0th shear horizontal (SH0) mode plate wave resonator, the performance is better and the thickness of LN is 7 times larger. The HAL SAW without a cavity is advantageous in terms of mechanical stability, thickness controllability and fabrication yield.

Thermal conductivity of pure silica MEL and MFI zeolite thin films

NASA Astrophysics Data System (ADS)

Coquil, Thomas; Lew, Christopher M.; Yan, Yushan; Pilon, Laurent

2010-08-01

This paper reports the room temperature cross-plane thermal conductivity of pure silica zeolite (PSZ) MEL and MFI thin films. PSZ MEL thin films were prepared by spin coating a suspension of MEL nanoparticles in 1-butanol solution onto silicon substrates followed by calcination and vapor-phase silylation with trimethylchlorosilane. The mass fraction of nanoparticles within the suspension varied from 16% to 55%. This was achieved by varying the crystallization time of the suspension. The thin films consisted of crystalline MEL nanoparticles embedded in a nonuniform and highly porous silica matrix. They featured porosity, relative crystallinity, and MEL nanoparticles size ranging from 40% to 59%, 23% to 47% and 55 nm to 80 nm, respectively. PSZ MFI thin films were made by in situ crystallization, were b-oriented, fully crystalline, and had a 33% porosity. Thermal conductivity of these PSZ thin films was measured at room temperature using the 3ω method. The cross-plane thermal conductivity of the MEL thin films remained nearly unchanged around 1.02±0.10 W m-1 K-1 despite increases in (i) relative crystallinity, (ii) MEL nanoparticle size, and (iii) yield caused by longer nanoparticle crystallization time. Indeed, the effects of these parameters on the thermal conductivity were compensated by the simultaneous increase in porosity. PSZ MFI thin films were found to have similar thermal conductivity as MEL thin films even though they had smaller porosity. Finally, the average thermal conductivity of the PSZ films was three to five times larger than that reported for amorphous sol-gel mesoporous silica thin films with similar porosity and dielectric constant.

Surface-functionalized mesoporous carbon materials

DOEpatents

Dai, Sheng; Gorka, Joanna; Mayes, Richard T.

2016-02-02

A functionalized mesoporous carbon composition comprising a mesoporous carbon scaffold having mesopores in which polyvinyl polymer grafts are covalently attached, wherein said mesopores have a size of at least 2 nm and up to 50 nm. Also described is a method for producing the functionalized mesoporous composition, wherein a reaction medium comprising a precursor mesoporous carbon, vinyl monomer, initiator, and solvent is subjected to sonication of sufficient power to result in grafting and polymerization of the vinyl monomer into mesopores of the precursor mesoporous carbon. Also described are methods for using the functionalized mesoporous carbon, particularly in extracting metal ions from metal-containing solutions.

Giant magnetoresistance (GMR) behavior of electrodeposited NiFe/Cu multilayers: Dependence of non-magnetic and magnetic layer thicknesses

NASA Astrophysics Data System (ADS)

Kuru, Hilal; Kockar, Hakan; Alper, Mursel

2017-12-01

Giant magnetoresistance (GMR) behavior in electrodeposited NiFe/Cu multilayers was investigated as a function of non-magnetic (Cu) and ferromagnetic (NiFe) layer thicknesses, respectively. Prior to the GMR analysis, structural and magnetic analyses of the multilayers were also studied. The elemental analysis of the multilayers indicated that the Cu and Ni content in the multilayers increase with increasing Cu and NiFe layer thickness, respectively. The structural studies by X-ray diffraction revealed that all multilayers have face centred cubic structure with preferred (1 1 0) crystal orientation as their substrates. The magnetic properties studied with the vibrating sample magnetometer showed that the magnetizations of the samples are significantly affected by the layer thicknesses. Saturation magnetisation, Ms increases from 45 to 225 emu/cm3 with increasing NiFe layer thickness. The increase in the Ni content of the multilayers with a small Fe content causes an increase in the Ms. And, the coercivities ranging from 2 to 24 Oe are between the soft and hard magnetic properties. Also, the magnetic easy axis of the multilayers was found to be in the film plane. Magnetoresistance measurements showed that all multilayers exhibited the GMR behavior. The GMR magnitude increases with increasing Cu layer thickness and reaches its maximum value of 10% at the Cu layer thickness of 1 nm, then it decreases. And similarly, the GMR magnitude increases and reaches highest value of pure GMR (10%) for the NiFe layer thickness of 3 nm, and beyond this point GMR decreases with increasing NiFe layer thickness. Some small component of the anisotropic magnetoresistance was also observed at thin Cu and thick NiFe layer thicknesses. It is seen that the highest GMR values up to 10% were obtained in electrodeposited NiFe/Cu multilayers up to now. The structural, magnetic and magnetoresistance properties of the NiFe/Cu were reported via the variations of the thicknesses of Cu and NiFe layers with stressing the role of layer thicknesses on the high GMR behavior.

Influence of the growth parameters on the electronic and magnetic properties of La0.67Sr0.33MnO3 epitaxial thin films

NASA Astrophysics Data System (ADS)

Annese, E.; Mori, T. J. A.; Schio, P.; Rache Salles, B.; Cezar, J. C.

2018-04-01

The implementation of La0.67Sr0.33MnO3 thin films in multilayered structures in organic and inorganic spintronics devices requires the optimization of their electronic and magnetic properties. In this work we report the structural, morphological, electronic and magnetic characterizations of La0.67Sr0.33MnO3 epitaxial thin films on SrTiO3 substrates, grown by pulsed laser deposition under different growing conditions. We show that the fluence of laser shots and in situ post-annealing conditions are important parameters to control the tetragonality (c/a) of the thin films. The distortion of the structure has a remarkable impact on both surface and bulk magnetism, allowing the tunability of the materials properties for use in different applications.

Radiation Damage Effects in Far Ultraviolet Filters and Substrates

NASA Technical Reports Server (NTRS)

Keffer, Charles E.; Torr, Marsha R.; Zukic, Muamer; Spann, James F.; Torr, Douglas G.; Kim, Jongmin

1993-01-01

New advances in VUV thin film filter technology have been made using filter designs with multilayers of materials such as Al2O3, BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2. Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 X 9 R(sub E) orbit will expose the instrument to approximately 275 krads of radiation. In view of the fact that no previous studies have been made on potential radiation damage of these materials in the thin film format, we report on such an assessment here. Transmittances and reflectances of BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2 thin films on MgF2 substrates, Al2O3 thin films on fused silica substrates, uncoated fused silica and MgF2, and four multilayer filters made from these materials were measured from 120 nm to 180 nm before and after irradiation by 250 krads from a Co-60 gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 nm to 300 nm indicated a 3 - 5% radiation-induced absorption near 260 nm in some of the samples with MgF2 substrates. From these measurements it is concluded that far ultraviolet filters made from the materials tested should experience less that 5% change from exposure to up to 250 krads of high energy radiation in space applications.

Highly accurate thickness measurement of multi-layered automotive paints using terahertz technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krimi, Soufiene; Beigang, René; Klier, Jens

2016-07-11

In this contribution, we present a highly accurate approach for thickness measurements of multi-layered automotive paints using terahertz time domain spectroscopy in reflection geometry. The proposed method combines the benefits of a model-based material parameters extraction method to calibrate the paint coatings, a generalized Rouard's method to simulate the terahertz radiation behavior within arbitrary thin films, and the robustness of a powerful evolutionary optimization algorithm to increase the sensitivity of the minimum thickness measurement limit. Within the framework of this work, a self-calibration model is introduced, which takes into consideration the real industrial challenges such as the effect of wet-on-wetmore » spray in the painting process.« less

Experimental study of Bloch vector analysis in nonlinear, finite, dissipative systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

D'Aguanno, G.; Mattiucci, N.; C. M. Bowden Facility, Building 7804, RDECOM, Redstone Arsenal, Alabama 35898

2010-01-15

We have investigated and experimentally demonstrated the applicability of the Bloch vector for one-dimensional, nonlinear, finite, dissipative systems. The case studied is the second harmonic generation from metallodielectric multilayer filters. In particular, we have applied the Bloch vector analysis to Ag/Ta{sub 2}O{sub 5} thin-film multilayer samples and shown the importance of the phase matching calculated through the Bloch vector. The nonlinear coefficients extracted from experimental results are consistent with previous studies. Nowadays, metal-based nanostructures play a fundamental role in nonlinear nanophotonics and nanoplasmonics. Our results clearly suggest that even in these forefront fields the Bloch vector continues to play anmore » essential role.« less

Impact of Dynamic Specimen Shape Evolution on the Atom Probe Tomography Results of Doped Epitaxial Oxide Multilayers: Comparison of Experiment and Simulation

DOE PAGES

Madaan, Nitesh; Bao, Jie; Nandasiri, Manjula I.; ...

2015-08-31

The experimental atom probe tomography results from two different specimen orientations (top-down and side-ways) of a high oxygen ion conducting Samaria-doped-ceria/Scandia-stabilized-zirconia multilayer thin film solid oxide fuel cell electrolyte was correlated with level-set method based field evaporation simulations for the same specimen orientations. This experiment-theory correlation explains the dynamic specimen shape evolution and ion trajectory aberrations that can induce density artifacts in final reconstruction leading to inaccurate estimation of interfacial intermixing. This study highlights the need and importance of correlating experimental results with field evaporation simulations when using atom probe tomography for studying oxide heterostructure interfaces.

Fluorescence and multilayer structure of the scorpion cuticle

NASA Astrophysics Data System (ADS)

Chen, Yu-Jen; Chiu, Pei-Ju; Lee, Cheng-Chung

2015-09-01

We collect the scorpions, Isometrus maculates, in different instars to analyze the photoluminescence (PL), micro-structure of cuticles and their correlation. The photoluminescence is excited by 405 nm solid laser in room temperature and detected by BWtek BRC 112E spectrometer. The result shows that the intensity of photoluminescence positively correlate to instars of scorpion. The images of micro-structures of cuticles captured by scanning electron microscope (SEM) present the multilayer structure in detail. The samples are prepared in small piece to ensure that the PL and SEM data are caught from the same area. The correlation between instars and intensity of photoluminescence is explained according to micro-structures via the thin-film optics theory.

Nanostructured Anodic Multilayer Dielectric Stacked Metal-Insulator-Metal Capacitors.

PubMed

Karthik, R; Kannadassan, D; Baghini, Maryam Shojaei; Mallick, P S

2015-12-01

This paper presents the fabrication of Al2O3/TiO2/Al2O3 metal-insulator-metal (MIM) capacitor using anodization technique. High capacitance density of > 3.5 fF/μm2, low quadratic voltage coefficient of capacitance of < 115 ppm/V2 and a low leakage current density of 4.457 x 10(-11) A/cm2 at 3 V are achieved which are suitable for analog and mixed signal applications. We found that the anodization voltage played a major role in electrical and structural properties of the thin film. This work suggests that the anodization method can offer crystalline multilayer dielectric stack required for high performance MIM capacitor.

Sharp focusing of laser light by multilayer cylinders with circular cross-section

NASA Astrophysics Data System (ADS)

Kozlova, E. S.

2018-04-01

In this paper, the focusing of laser light at 532 nm by dielectric cylinders with a metal shells is studied by using COMSOL Multiphysics. The analysis of cylinder design which proposed multilayered shell shows that a microcylinder with a gold-silver (or silver-gold) shell can improve the focusing process, especially in the case of TM polarization. The microcylinder with thin internal silver layer of 1 nm and outside gold layer of 9 nm focus TE-polarized light to nanojet with maximal intensity of 5.65 a.u., full width and full length at half maximum of intensity of of 0.39λ and 0.72λ, respectively.

Seed/catalyst-free growth of zinc oxide nanostructures on multilayer graphene by thermal evaporation

PubMed Central

2014-01-01

We report the seed/catalyst-free growth of ZnO on multilayer graphene by thermal evaporation of Zn in the presence of O2 gas. The effects of substrate temperatures were studied. The changes of morphologies were very significant where the grown ZnO structures show three different structures, i.e., nanoclusters, nanorods, and thin films at 600°C, 800°C, and 1,000°C, respectively. High-density vertically aligned ZnO nanorods comparable to other methods were obtained. A growth mechanism was proposed based on the obtained results. The ZnO/graphene hybrid structure provides several potential applications in electronics and optoelectronics. PMID:24533793

Multi-layer light-weight protective coating and method for application

NASA Technical Reports Server (NTRS)

Wiedemann, Karl E. (Inventor); Clark, Ronald K. (Inventor); Taylor, Patrick J. (Inventor)

1992-01-01

A thin, light-weight, multi-layer coating is provided for protecting metals and their alloys from environmental attack at high temperatures. A reaction barrier is applied to the metal substrate and a diffusion barrier is then applied to the reaction barrier. A sealant layer may also be applied to the diffusion barrier if desired. The reaction barrier is either non-reactive or passivating with respect to the metal substrate and the diffusion barrier. The diffusion barrier is either non-reactive or passivating with respect to the reaction barrier and the sealant layer. The sealant layer is immiscible with the diffusion barrier and has a softening point below the expected use temperature of the metal.

Development and production of a multilayer-coated x-ray reflecting stack for the Athena mission

NASA Astrophysics Data System (ADS)

Massahi, S.; Ferreira, D. D. M.; Christensen, F. E.; Shortt, B.; Girou, D. A.; Collon, M.; Landgraf, B.; Barriere, N.; Krumrey, M.; Cibik, L.; Schreiber, S.

2016-07-01

The Advanced Telescope for High-Energy Astrophysics, Athena, selected as the European Space Agency's second large-mission, is based on the novel Silicon Pore Optics X-ray mirror technology. DTU Space has been working for several years on the development of multilayer coatings on the Silicon Pore Optics in an effort to optimize the throughput of the Athena optics. A linearly graded Ir/B4C multilayer has been deposited on the mirrors, via the direct current magnetron sputtering technique, at DTU Space. This specific multilayer, has through simulations, been demonstrated to produce the highest reflectivity at 6 keV, which is a goal for the scientific objectives of the mission. A critical aspect of the coating process concerns the use of photolithography techniques upon which we will present the most recent developments in particular related to the cleanliness of the plates. Experiments regarding the lift-off and stacking of the mirrors have been performed and the results obtained will be presented. Furthermore, characterization of the deposited thin-films was performed with X-ray reflectometry at DTU Space and in the laboratory of the Physikalisch-Technische Bundesanstalt at the synchrotron radiation facility BESSY II.

Energy-Sensitive Ion- and Cathode-Luminescent Radiation-Beam Monitors Based on Multilayer Thin-Film Designs.

PubMed

Gil-Rostra, Jorge; Ferrer, Francisco J; Espinós, Juan Pedro; González-Elipe, Agustín R; Yubero, Francisco

2017-05-17

A multilayer luminescent design concept is presented to develop energy-sensitive radiation-beam monitors on the basis of colorimetric analysis. Each luminescent layer within the stack consists of rare-earth-doped transparent oxides of optical quality and a characteristic luminescent emission under excitation with electron or ion beams. For a given type of particle beam (electron, protons, α particles, etc.), its penetration depth and therefore its energy loss at a particular buried layer within the multilayer stack depend on the energy of the initial beam. The intensity of the luminescent response of each layer is proportional to the energy deposited by the radiation beam within the layer, so characteristic color emission will be achieved if different phosphors are considered in the layers of the luminescent stack. Phosphor doping, emission efficiency, layer thickness, and multilayer structure design are key parameters relevant to achieving a broad colorimetric response. Two case examples are designed and fabricated to illustrate the capabilities of these new types of detector to evaluate the kinetic energy of either electron beams of a few kilo-electron volts or α particles of a few mega-electron volts.

Self-assembled multilayers and photoluminescence properties of a new water-soluble poly(para-phenylene)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, X.; Li, D.; Luett, M.

1998-07-01

This paper reports the synthesis and characterizations of a new water-soluble poly(paraphenylene) (PPP) and its applications in preparing self-assembled multi-layer films. This new water-soluble conducting polymer was prepared through the sulfonation reaction of poly(p-quarterphenylene-2,2{prime}-dicarboxylic acid). The incorporation of sulfonate groups has dramatically improved PPP's solubility in water at a wide pH range, whereas previous PPP is only slightly soluble in basic solutions. Dilute aqueous solutions of this polymer with acidic, neutral or basic pH emit brilliant blue light while irradiated with UV light. The sulfonated PPP emits from 350 nm to 455 nm with a maximum intensity at 380 nm.more » Self-assembled multilayers of this sulfonated PPP were constructed with a positively charged polymer poly(diallyl dimethyl ammonium chloride) and characterized with various surface analyses. Conductive (RuO{sub 2} and ITO), semiconductive (Si wafer), and non-conductive (SiO{sub 2}) substrates were used in the preparation of self-assembled multilayers. Electrical, optical and structural properties of these novel self-assembled thin films will be discussed.« less

Self-assembled multilayers and photoluminescence properties of a new water-soluble poly(para-phenylene)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, X.; Li, D.Q.; Luett, M.

1998-03-01

This paper reports the synthesis and characterizations of a new water-soluble poly(para-phenylene) (PPP) and its applications in preparing self-assembled multilayer films. This new water-soluble conducting polymer was prepared through the sulfonation reaction of poly(p-quarterphenylene-2,2{prime}-dicarboxylic acid). The incorporation of sulfonate groups has dramatically improved PPP`s solubility in water at a wide pH range, whereas previous PPP is only slightly soluble in basic solutions. Dilute aqueous solutions of this polymer with acidic, neutral or basic pH emit brilliant blue light while irradiated with UV light. The sulfonated PPP emits from 350 nm to 455 nm with a maximum intensity at 380 nm.more » Self-assembled multilayers of this sulfonated PPP were constructed with a positively charged polymer poly(diallyl dimethyl ammonium chloride) and characterized with various surface analyses. Conductive (RuO{sub 2} and ITO), semiconductive (Si wafer), and non-conductive (SiO{sub 2}) substrates were used in the preparation of self-assembled multilayers. Electrical, optical and structural properties of these novel self-assembled thin films will be discussed.« less

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

PubMed

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

2015-05-04

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

Fabrication and properties of light-emitting diodes based on self-assembled multilayers of poly(phenylene vinylene)

NASA Astrophysics Data System (ADS)

Fou, A. C.; Onitsuka, O.; Ferreira, M.; Rubner, M. F.; Hsieh, B. R.

1996-05-01

Light-emitting diodes have been fabricated from self-assembled multilayers of poly(p-phenylene vinylene) (PPV) and two different polyanions; polystyrene sulfonic acid (SPS) and polymethacrylic acid (PMA). The type of polyanion used to assemble the multilayer thin films was found to dramatically influence the behavior and performance of devices fabricated with indium tin oxide and aluminum electrodes. Light-emitting devices fabricated from PMA/PPV multilayers were found to exhibit luminance levels in the range of 20-60 cd/m2, a thickness dependent turn-on voltage and classical rectifying behavior with rectification ratios greater than 105. In sharp contrast, the devices based on SPS/PPV exhibited near symmetric current-voltage curves, thickness independent turn-on voltages and much lower luminance levels. The significant difference in device behavior observed between these two systems is primarily due to a doping effect induced either chemically or electrochemically by the sulfonic acid groups of SPS. It was also found that the performance of these devices depends on the type of layer that is in contact with the Al top electrode thereby making it possible to manipulate device efficiency at the molecular level.

Thickness-dependent magneto-optical effects in hole-doped GaS and GaSe multilayers: a first-principles study

NASA Astrophysics Data System (ADS)

Li, Fei; Zhou, Xiaodong; Feng, Wanxiang; Fu, Botao; Yao, Yugui

2018-04-01

Recently, two-dimensional (2D) GaS and GaSe nanosheets were successfully fabricated and the measured electronic, mechanical, and optoelectronic properties are excellent. Here, using the first-principles density functional theory, we investigate the magnetic, optical, and magneto-optical (MO) Kerr and Faraday effects in hole-doped GaS and GaSe multilayers. GaS and GaSe monolayers (MLs) manifest ferromagnetic ground states by introducing even a small amount of hole doping, whereas the magnetism in GaS and GaSe multilayers are significantly different under hole doping. Our results show that ferromagnetic states can be easily established in GaS bilayers and trilayers under proper hole doping, however, most of GaSe multilayers are more favorable to nonmagnetic states. The magnetic moments in GaS multilayers are weakened remarkably with the increasing of thin film thickness and are negligible more than three MLs. This leads to the thickness dependence of MO Kerr and Faraday effects. Furthermore, the MO effects strongly depend on the doping concentration and therefore are electrically controllable by adjusting the number of holes via gate voltage. The substrate effects on the MO properties are also discussed. Combining the unique MO and other interesting physical properties make GaS and GaSe a superior 2D material platform for semiconductor MO and spintronic nanodevices.

Neat monolayer tiling of molecularly thin two-dimensional materials in 1 min

PubMed Central

Matsuba, Kazuaki; Wang, Chengxiang; Saruwatari, Kazuko; Uesusuki, Yusuke; Akatsuka, Kosho; Osada, Minoru; Ebina, Yasuo; Ma, Renzhi; Sasaki, Takayoshi

2017-01-01

Controlled arrangement of molecularly thin two-dimensional (2D) materials on a substrate, particularly into precisely organized mono- and multilayer structures, is a key to design a nanodevice using their unique and enhanced physical properties. Several techniques such as mechanical transfer process and Langmuir-Blodgett deposition have been applied for this purpose, but they have severe restrictions for large-scale practical applications, for example, limited processable area and long fabrication time, requiring skilled multistep operations. We report a facile one-pot spin-coating method to realize dense monolayer tiling of various 2D materials, such as graphene and metal oxide nanosheets, within 1 min over a wide area (for example, a 30-mmφ substrate). Centrifugal force drives the nanosheets in a thin fluid layer to the substrate edge where they are packed edge to edge all the way to the central region, without forming overlaps. We investigated the relationship between precursor concentration, rotation speed, and ultraviolet-visible absorbance and developed an effective method to optimize the parameters for neat monolayer films. The multilayer buildup is feasible by repeating the spin-coating process combined with a heat treatment at moderate temperature. This versatile solution-based technique will provide both fundamental and practical advancements in the rapid large-scale production of artificial lattice-like films and nanodevices based on 2D materials. PMID:28695198

Multilayer thin films with compositional PbZr0.52Ti0.48O3/Bi1.5Zn1.0Nb1.5O7 layers for tunable applications

PubMed Central

Yu, Shihui; Li, Lingxia; Zhang, Weifeng; Sun, Zheng; Dong, Helei

2015-01-01

The dielectric properties and tunability of multilayer thin films with compositional PbZr0.52Ti0.48O3/Bi1.5Zn1.0Nb1.5O7 (PZT/BZN) layers (PPBLs) fabricated by pulsed laser deposition on Pt/TiO2/SiO2/Si substrate have been investigated. Dielectric measurements indicate that the PZT/BZN bilayer thin films exhibit medium dielectric constant of about 490, low loss tangent of 0.017, and superior tunable dielectric properties (tunability = 49.7% at 500 kV/cm) at a PZT/BZN thickness ratio of 3, while the largest figure of merit is obtained as 51.8. The thickness effect is discussed with a series connection model of bilayer capacitors, and the calculated dielectric constant and loss tangent are obtained. Furthermore, five kinds of thin–film samples comprising single bilayers, two, three, four and five PPBLs were also elaborated with the final same thickness. The four PPBLs show the largest dielectric constant of ~538 and tunability of 53.3% at a maximum applied bias field of 500 kV/cm and the lowest loss tangent of ~0.015, while the largest figure of merit is 65.6. The results indicate that four PPBLs are excellent candidates for applications of tunable devices. PMID:25960043

Pulsed Laser Deposition Growth of Delafossite (CuFeO2) thin films and multilayers

NASA Astrophysics Data System (ADS)

Joshi, Toyanath; Ferrari, Piero; Borisov, Pavel; Cabrera, Alejandro; Lederman, David

2014-03-01

Owing to its narrow band gap (<2 eV) and p-type conductivity delafossite CuFeO2 is attractive for applications in the field of solar energy conversion. Obtaining pure phase CuFeO2 thin films, however, is relatively difficult. It is necessary to maintain the lowest possible Cu valency (+1) in order to avoid forming the comparably stable spinel compound CuFe2O4. We present a systematic study of the pulsed laser deposition (PLD) growth conditions for epitaxial (00.1) oriented CuFeO2 thin films on Al2O3 (00.1) substrates. The secondary impurity phase, CuFe2O4, was removed completely by optimizing the growth conditions. RHEED, XRD and TEM showed that the pure phase delafossite films are highly epitaxial to the substrate. The chemical purity was verified by Raman and XPS. The indirect bandgap of 1.15 eV was measured using infrared reflectivity, and is in agreement with the CuFeO2 bulk value. Finally, we discuss the growth and structural characterization of delafossite multilayers, CuFeO2/CuGaO2. This work was supported by a Research Challenge Grant from the West Virginia Higher Education Policy Commission (HEPC.dsr.12.29) and the Microelectronics Advanced Research Corporation (Contract # 2013-MA-2382) at WVU.